Name: employing pressurized hot water extraction (phwe) to explore natural products chemistry in the undergraduate laboratory
Uploaded: 2018-11-07T13:00:00
Description: Watch this Scientific Journal Video about Employing Pressurized Hot Water Extraction PHWE to Explore Natural Products Chemistry in the Undergraduate Laboratory at JoVE.com

The authors acknowledge the School of Natural Sciences - Chemistry, University of Tasmania and the School of Chemistry, The University of Sydney for financial support. B.J.D. and J.J. thank the Australian Government for Research Training Program Scholarships.

NOTE: It is advisable that all procedures are performed in a fume hood. Students must wear appropriate personal protective equipment at all times in the laboratory and the safety data sheets (SDS) associated with each reagent must be consulted before use.
1. PHWE of cloves: isolation of eugenol and acetyleugenol
<ol>
	<li>Extraction of eugenol and acetyleugenol from cloves
	<ol>
		<li>Place coarsely ground cloves (12.5 g) in a 250-mL beaker.</li>
		<li>Add s...

<ol>
	<li>Newman, D. J., Cragg, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+Products+as+Sources+of+New+Drugs+from+1981+to+2014.">Natural Products as Sources of New Drugs from 1981 to 2014.</a> Journal of Natural Products. 79, 629-661 (2016).</li><li>Barnes, E. C., Kumar, R., Davis, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+isolated+natural+products+as+scaffolds+for+the+generation+of+chemically+diverse+screening+libraries+for+drug+discovery.">The use of isolated natural products as scaffolds for the generation of chemically diverse screening libraries for drug discovery.</a> Natural Product Reports. 33, 372-381 (2016).</li><li>DeCorte, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Underexplored+Opportunities+for+Natural+Products+in+Drug+Discovery.">Underexplored Opportunities for Natural Products in Drug Discovery.</a> Journal of Medicinal Chemistry. 59, 9295-9304 (2016).</li><li>Bucar, F., Wube, A., Schmid, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+product+isolation+-+how+to+get+from+biological+material+to+pure+compounds.">Natural product isolation - how to get from biological material to pure compounds.</a> Natural Product Reports. 30, 525-545 (2013).</li><li>Sticher, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+product+isolation.">Natural product isolation.</a> Natural Product Reports. 25, 517-554 (2008).</li><li>Just, J., Deans, B. J., Olivier, W. J., Paull, B., Bissember, A. C., Smith, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+Method+for+the+Rapid+Extraction+of+Natural+Products:+Efficient+Isolation+of+Shikimic+Acid+from+Star+Anise.">New Method for the Rapid Extraction of Natural Products: Efficient Isolation of Shikimic Acid from Star Anise.</a> Organic Letters. 17, 2428-2430 (2015).</li><li>Caprioli, G., Cortese, M., Cristalli, G., Maggi, F., Odello, L., Ricciutelli, M., Sagratini, G., Sirocchi, V., Tomassoni, G., Vittori, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimization+of+espresso+machine+parameters+through+the+analysis+of+coffee+odorants+by+HS-SPME-GC/MS.">Optimization of espresso machine parameters through the analysis of coffee odorants by HS-SPME-GC/MS.</a> Food Chemistry. 135, 1127-1133 (2012).</li><li>Just, J., Jordan, T. B., Paull, B., Bissember, A. C., Smith, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Practical+isolation+of+polygodial+from+Tasmannia+lanceolata:+a+viable+scaffold+for+synthesis.">Practical isolation of polygodial from Tasmannia lanceolata: a viable scaffold for synthesis.</a> Organic Biomolecular Chemistry. 13, 11200-11207 (2015).</li><li>Just, J., Bunton, G. L., Deans, B. J., Murray, N. L., Bissember, A. C., Smith, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extraction+of+Eugenol+from+Cloves+Using+an+Unmodified+Household+Espresso+Machine:+An+Alternative+to+Traditional+Steam+Distillation.">Extraction of Eugenol from Cloves Using an Unmodified Household Espresso Machine: An Alternative to Traditional Steam Distillation.</a> Journal of Chemical Education. 93, 213-216 (2016).</li><li>Deans, B. J., Bissember, A. C., Smith, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Practical+Isolation+of+Asperuloside+from+Coprosma+quadrifida+via+Rapid+Pressurised+Hot+Water+Extraction.">Practical Isolation of Asperuloside from Coprosma quadrifida via Rapid Pressurised Hot Water Extraction.</a> Australian Journal of Chemistry. 69, 1219-1222 (2016).</li><li>Deans, B. J., Just, J., Chetri, J., Burt, L. K., Smith, J. N., Kilah, N. L., de Salas, M., Gueven, N., Bissember, A. C., Smith, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pressurized+Hot+Water+Extraction+as+a+Viable+Bioprospecting+Tool:+Isolation+of+Coumarin+Natural+Products+from+Previously+Unexamined+Correa+(Rutaceae).">Pressurized Hot Water Extraction as a Viable Bioprospecting Tool: Isolation of Coumarin Natural Products from Previously Unexamined Correa (Rutaceae).</a> ChemistrySelect. 2, 2439-2443 (2017).</li><li>Deans, B. J., Olivier, W. J., Girbino, D., Bissember, A. C., Smith, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extraction+of+carboxylic+acid-containing+diterpenoids+from+Dodonaea+viscosa+via+pressurised+hot+water+extraction.">Extraction of carboxylic acid-containing diterpenoids from Dodonaea viscosa via pressurised hot water extraction.</a> Fitoterapia. 126, 65-68 (2018).</li><li>Deans, B. J., Kilah, N. L., Jordan, G. J., Bissember, A. C., Smith, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arbutin+Derivatives+Isolated+from+Ancient+Proteaceae:+Potential+Phytochemical+Markers+Present+in+Bellendena,+Cenarrhenes+and+Persoonia+Genera.">Arbutin Derivatives Isolated from Ancient Proteaceae: Potential Phytochemical Markers Present in Bellendena, Cenarrhenes and Persoonia Genera.</a> Journal of Natural Products. 81, 1241-1251 (2018).</li><li>Deans, B. J., Tedone, L., Bissember, A. C., Smith, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phytochemical+profile+of+the+rare,+ancient+clone+Lomatia+tasmanica+and+comparison+to+other+endemic+Tasmanian+species+L.+tinctoria+and+L.+polymorpha.">Phytochemical profile of the rare, ancient clone Lomatia tasmanica and comparison to other endemic Tasmanian species L. tinctoria and L. polymorpha.</a> Phytochemistry. 153, 74-78 (2018).</li><li>Deans, B. J., Skierka, B., Karagiannakis, B. W., Vuong, D., Lacey, E., Smith, J. A., Bissember, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Siliquapyranone:+a+Tannic+Acid+Tetrahydropyran-2-one+Isolated+from+the+Leaves+of+Carob+(Ceratonia+siliqua)+by+Pressurised+Hot+Water+Extraction.">Siliquapyranone: a Tannic Acid Tetrahydropyran-2-one Isolated from the Leaves of Carob (Ceratonia siliqua) by Pressurised Hot Water Extraction.</a> Australian Journal of Chemistry. 71, (2018).</li><li>Olivier, W. J., Kilah, N. L., Horne, J., Bissember, A. C., Smith, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ent-Labdane+Diterpenoids+from+Dodonaea+viscosa.">ent-Labdane Diterpenoids from Dodonaea viscosa.</a> Journal of Natural Products. 79, 3117-3126 (2016).</li><li>Rihak, K. J., Bissember, A. C., Smith, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polygodial:+A+viable+natural+product+scaffold+for+the+rapid+synthesis+of+novel+polycyclic+pyrrole+and+pyrrolidine+derivatives.">Polygodial: A viable natural product scaffold for the rapid synthesis of novel polycyclic pyrrole and pyrrolidine derivatives.</a> Tetrahedron. 74, 1167-1174 (2018).</li><li>Ntamila, M. S., Hassanali, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+Oil+of+Clove+and+Separation+of+Eugenol+and+Acetyl+Eugenol.">Isolation of Oil of Clove and Separation of Eugenol and Acetyl Eugenol.</a> Journal of Chemical Education. 53, 263 (1976).</li><li>Still, W. C., Kahn, M., Mitra, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+chromatographic+technique+for+preparative+separations+with+moderate+resolution.">Rapid chromatographic technique for preparative separations with moderate resolution.</a> Journal of Organic Chemistry. , 2923-2925 (1978).</li></ol>

The classical procedure for isolating eugenol from cloves by steam distillation has been part of the intermediate chemistry laboratory program at the University of Sydney for decades but was modernized to employ PHWE methodology in 2016 (Figure 1).9,18 This provided a number benefits. Firstly, utilizing household espresso machines in the laboratory environment immediately fascinated and engaged students by illustrating the applicatio...

The isolation and identification of natural products are of fundamental importance to the scientific community and society more generally.1 Bioprospecting, the search for valuable organic molecules found in nature,remains an indispensable process in the discovery of new drug leads and potential therapeutic agents. It is estimated that, from 1981-2014, ~75% of all approved small molecule pharmaceutical drugs were natural products, natural product-derived or natural product-inspired.1 Furthermore, natural products possess enormous structural and chemical diversity. For this reason, they also represent valuable chemical scaffolds that can be directly used in organic synthesis or in the development of chiral ligands and catalysts.2,3
Traditionally, relatively time-intensive procedures such as maceration, Soxhlet extraction, and steam distillation have been the mainstay of research focused on the isolation of secondary metabolites from plants.4 More modern extraction techniques, including accelerated solvent extraction, have focused on reducing extraction times and establishing greener protocols.4,5 In 2015, an original pressurized hot water extraction (PHWE) method was reported.6 This technique employed an unmodified household espresso machine to facilitate the rapid and particularly efficient extraction of shikimic acid from star anise. Espresso machines have been specifically designed and engineered to extract organic molecules from appropriately ground coffee beans. To achieve this, these instruments heat water at temperatures up to 96 &#176;C and at pressures of typically 9 bar.7 With this in mind, it is perhaps not surprising that espresso machines can be utilized to efficiently extract natural products from a range of plant material.
Subsequent studies involving a variety of terrestrial plant species have demonstrated the capacity of this PHWE technique to efficiently extract natural products across a relatively broad polarity range.6,8,9,10,11,12,13,14,15 Furthermore, compounds containing somewhat sensitive functional groups, such as aldehydes, epoxides, glycosides, and potentially epimerizable stereogenic centers were typically unaffected by the extraction process. The complementary nature of this technique relative to more traditional methods has also been demonstrated.12,16 This PHWE method has also been employed to isolate multi-gram quantities of natural products, which have been used to prepare novel natural product derivatives and in complex molecule synthesis more generally.8,11,17
It was identified that this new PHWE method could serve as a useful teaching tool that could be incorporated in the undergraduate laboratory. This primarily derives from the rapid nature of this technique relative to the traditional extraction methods that are often incompatible with the time constraints associated with undergraduate laboratory experiments. Consequently, this technique supplanted the traditional undergraduate chemistry laboratory experiment focused on the extraction of eugenol from cloves employing steam-distillation at the University of Tasmania.9,18 Since that time, variations of this experiment have been adopted by other universities and a modified experiment focusing on the PHWE of cloves now features in the undergraduate chemistry laboratory program at the University of Sydney (vide infra).
In order to demonstrate the practicality and feasibility of employing this new PHWE approach for teaching purposes, two protocols are presented as part of this study. The first part of this report highlights an experiment on the PHWE of eugenol and acetyleugenol from cloves which is part of the second-year undergraduate laboratory program at the University of Sydney (Figure 1). This experiment serves to introduce students to natural products chemistry while developing fundamental practical skills. The second part features an experiment on the PHWE of the endemic Australian plant species Correa reflexa which is part of the third-year undergraduate laboratory program at the University of Tasmania (Figure 2). This experiment is designed to simulate natural products bioprospecting and reinforce core laboratory techniques.11

<table border="0" cellpadding="0" cellspacing="0" style="width:1069px;" width="1070">
	<tbody>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">espresso machines</td>
			<td style="width:167px;">Breville/Sunbeam</td>
			<td style="width:520px;">Breville espresso machine model 800ES / Sunbeam EM3820 Caf&#233; Espresso II</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">rotary evporators</td>
			<td style="width:167px;">Buchi and Heidolph</td>
			<td style="width:520px;"></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">cloves (plant material)</td>
			<td>Dijon Food Pty Ltd</td>
			<td></td>
			<td>Cloves must be ground in a food processor for students.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Correa reflexa (plant material)</td>
			<td>sample obtained in Tasmania</td>
			<td>Sample collected from mature shrubs in the Thomas Crawford Reserve at the University of Tasmania</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">sand</td>
			<td style="width:167px;">Ajax</td>
			<td style="width:520px;">1199</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">ethanol</td>
			<td>Redoc Chemicals</td>
			<td>E95 F3</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">hexanes</td>
			<td>Ajax</td>
			<td>251</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">magnesium sulfate</td>
			<td>Ajax</td>
			<td>1548</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">diethyl ether</td>
			<td>Merck</td>
			<td>1009215000</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">silica on aluminium TLC plates</td>
			<td>Merck</td>
			<td>1055540001</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">eugenol</td>
			<td>Merck</td>
			<td>1069620100</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">eugenyl acetate</td>
			<td>Aldrich</td>
			<td>W246905</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">acetone</td>
			<td>Redox Chemicals</td>
			<td>Aceton13</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">cyclohexane</td>
			<td>ChemSupply</td>
			<td>CA019</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">silica gel 60</td>
			<td>Trajan</td>
			<td>5134312</td>
			<td style="width:167px;">40 - 63um (230-400mesh)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Congo red paper</td>
			<td>ChemSupply</td>
			<td>IS070-100S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">32% hydrochloric acid</td>
			<td>Ajax</td>
			<td>256</td>
			<td></td>
		</tr>
	</tbody>
</table>

employing pressurized hot water extraction (phwe) to explore natural products chemistry in the undergraduate laboratory

A recently developed pressurized hot water extraction (PHWE) method which utilizes an unmodified household espresso machine to facilitate natural products research has also found applications as an effective teaching tool. Specifically, this technique has been used to introduce second- and third-year undergraduates to aspects of natural products chemistry in the laboratory. In this report, two experiments are presented: the PHWE of eugenol and acetyleugenol from cloves and the PHWE of seselin and (+)-epoxysuberosin from the endemic Australian plant species Correa reflexa. By employing PHWE in these experiments, the crude clove extract, enriched in eugenol and acetyleugenol, was obtained in 4-9% w/w from cloves by second-year undergraduates and seselin and (+)-epoxysuberosin were isolated in yields of up to 1.1% w/w and 0.9% w/w from C. reflexa by third-year students. The former exercise was developed as a replacement for the traditional steam distillation experiment providing an introduction to extraction and separation techniques, while the latter activity featured guided-inquiry teaching methods in an effort to simulate natural products bioprospecting. This primarily derives from the rapid nature of this PHWE technique relative to traditional extraction methods that are often incompatible with the time constraints associated with undergraduate laboratory experiments. This rapid and practical PHWE method can be used to efficiently isolate various classes of organic molecules from a range of plant species. The complementary nature of this technique relative to more traditional methods has also been demonstrated previously.

PHWE of cloves. When attempting to perform the liquid-liquid extraction step, students often encountered emulsions (the addition of brine was typically not effective). At this stage, students were instructed to allow the mixture to stand in the separating funnel while they explored the effects of eluent composition on the separation of eugenol and acetyleugenol by TLC. It should be noted that hexane can be substituted with either heptane or dichloromethane in the liquid-liquid extraction ...

Watch this Scientific Journal Video about Employing Pressurized Hot Water Extraction PHWE to Explore Natural Products Chemistry in the Undergraduate Laboratory at JoVE.com

Employing Pressurized Hot Water Extraction PHWE to Explore Natural Products Chemistry in the Undergraduate Laboratory

Here, we employ a pressurized hot water extraction (PHWE) method, which utilizes an unmodified household espresso machine to introduce undergraduates to natural products chemistry in the laboratory. Two experiments are presented: PHWE of eugenol and acetyleugenol from cloves and PHWE of seselin and (+)-epoxysuberosin from the Australian plant Correa reflexa.

Employing Pressurized Hot Water Extraction (PHWE) to Explore Natural Products Chemistry in the Undergraduate Laboratory

A recently developed pressurized hot water extraction (PHWE) method which utilizes an unmodified household espresso machine to facilitate natural products ...

This technique represents an inherently practical and efficient strategy for natural products extraction in isolation chemistry. And we think it's a useful and complimentary extraction tool. Because this is a rapid flow process, the extract is only heated for a short period and the extraction of intractable plant pigments which often complicate purification is minimized.We think that this technique is well suited to enabling chemo taxonomic sampling in addition to medicinal chemistry by facilitating bio prospecting which is the search for valuable molecules in nature. Visual demonstration of this method is important as a sample preparation in extraction steps are most effectively explained visually. This also reinforces the simplicity of the extraction and its appropriate use in the undergraduate laboratory environment.Place 12.5 grams of coarsely ground cloves into a 250 milliliter beaker. Add 12.5 grams of sand and mix well. Next, collect a portafilter and load the basket with the entire clove and sand mixture.Use a tamper to lightly compress the sample making sure not to compress it too much which would prevent fluid from flowing. Load the portafilter into the espresso machine and place a clear 250 milliliter beaker beneath it. Add a solution containing 30 percent ethanol in water to the water tank.Using the espresso machine, collect 100 milliliters of the extract. Let the portafilter finish dripping and then remove it from the espresso machine. Use a spatula to remove the clove grinds from the portafilter and discard them into a solid waste container.Rinse out any residual solids with tap water in the sink. Transfer the beaker containing the clove extracts to an ice bath and let it cool until the temperature reduced to at least 30 degrees celsius. In a fume hood, pour the cooled extract into a 250 milliliter separatory funnel.Add 30 milliliters of hexane and mix by shaking gently. Place the separatory funnel in a ring clamp that is fitted to a retort stand and allow the aqueous and organic layers to separate. It can take up to 10 minutes for the layers to separate so we recommend that you carry out solvent optimization of TLCs while you wait.Collect the aqueous layer back into the 250 milliliter beaker. Transfer the organic layer which contains the product to a clean 250 milliliter conical flask. Then pour the aqueous face pack into the separatory funnel.Extract the aqueous layer two additional times with hexane. Using 30 milliliters of hexane each time. Combine the organic layers into the same 250 milliliter conical flask after each extraction.After the third liquid extraction pour the combined organic extract into the separatory funnel. Wash the organic extract by adding 100 milliliters of water and shaking vigorously. Collect the organic layer into a clean 250 milliliter conical flask.And then dry it by adding magnesium sulfate and swirling. Filter the dried mixture through fluted filter paper contained in a glass funnel into the round bottom flask. Using a rotary evaporator, evaporate the solvent from the collected filtrate.Then weigh the flask containing the resultant oil. Add 10 milliliters of hexane to the round bottom flask containing the crude eugenol containing extract. Pour the resulting solution into a 250 milliliter separatory funnel.Rinse the round bottom flask with 10 milliliters of hexane and add this to the separatory funnel. Extract the hexane solution twice with three molar aqueous sodium hydroxide via liquid liquid extraction. Using 25 milliliters of sodium hydroxide for each extraction.Collect the aqueous layers from each extraction and combine them in a 250 milliliter conical flask. Collect the organic layer in a 50 milliliter conical flask. Then dry it by adding magnesium sulfate to the flask and swirling it.Filter the solution through fluted filter paper contained in a glass funnel into a pre-weighed 100 milliliter round bottom flask. Discard the solid residue then use a rotary evaporator to remove the solvent. After this weigh the round bottom flask which now contains the resulting oil on a top pan balance.Next place the conical flask that contains the combined aqueous layers into an ice water bath. Swirl the flask while slowly adding a 10 molar solution of hydrochloric acid until a white emulsion is formed. Use a pipette to transfer a drop of this solution onto Congo red paper to test its acidity.The paper should turn blue. After this transfer the milky aqueous emulsion to a 250 milliliter separating flask. Make sure that the emulsion is at room temperature and then perform liquid liquid extraction twice using 30 milliliters of hexane per extraction.Combine the two hexane extracts into a clean 100 milliliter conical flask. Add magnesium sulfate to dry the solution. Filter the solution through fluted filter paper contained in a glass funnel into the pre-weighed 100 milliliter round bottom flask.Then use a rotary evaporator to remove the solvent. After this weigh the round bottom flask which now contains the resulting oil on a top pan balance. Using an electric spice grinder grind 10 grams of correa reflexa leaves for 20 to 30 seconds.Transfer the ground plant material to a 250 milliliter beaker. Add approximately two grams of coarse sand. Mix the sand and plant material together and then transfer it into the basket of a portafilter.Use a tamper to lightly compress the sample making sure not to compress it too much. Add about 300 milliliters of 35 percent ethanol in water to the espresso machine tank. Load the portafilter into the espresso machine and place a 250 milliliter beaker beneath it.Then collect approximately 100 milliliters of extract. Wait for about one minute then collect another 100 milliliters of extract. Transfer this mixture to an ice bath to cool.Use a rotary evaporator with a water bath temperature of 40 degrees celsius to evaporate the ethanol. Next transfer the aqueous extract to a seperatory funnel. Extract the solution twice with ethyl acetate using 50 milliliters of ethyl acetate per extraction.Combine the organic extracts. Add magnesium sulfate and swirl the flask to dry the solution. Then use a centered glass funnel to filter the solution and use a rotary evaporator to obtain the crude extract.In this procedure students are allocated a TLC solvent ratio of acetone and cyclohexane and provided with pure standards of eugenol and acetyl-eugenol. TLC analysis is performed and the effects of solvent composition on the retention factor are considered. The optimum solvent compositions are seen to typically range between five and 20 percent acetone cyclohexane.With a delta retention factor of 0.1 to 0.2. The different acid based properties of the two major organic molecules are then exploited to separate them by liquid liquid extraction. Typically eugenol was isolated in a yield of 45 to 65 percent of the crude extract while acetyl-eugenol was isolated in a yield of five to 10 percent.Students then utilized the optimized eluant to determine the success of their liquid liquid extraction by comparison of their extracts to the pure reference samples by TLC. Advanced students then subject half their isolated crude oil to flash column chromatography. While the complete separation of eugenol from acetyl-eugenol is rarely achieved due to their close retention factors, a few fractions containing pure eugenol are generally collected.Following this procedure, methods like nuclear magnetic resonance spectroscopy and gas chromatography mass spectrometry can be performed characterized the isolated compounds. Don't forget, working with hot liquids, relatively high pressures and corrosive liquids can be hazardous so precautions such as wearing personal protective equipment should be taken.

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Hot Biological Catalysis: Isothermal Titration Calorimetry to Characterize Enzymatic Reactions

Isothermal titration calorimetry (ITC) is a well-described technique that measures the heat released or absorbed during a chemical reaction, using it as an intrinsic probe to characterize virtually every chemical process. Nowadays, this technique is extensively applied to determine thermodynamic parameters of biomolecular binding equilibria. In addition, ITC has been demonstrated to be able of directly measuring kinetics and thermodynamic parameters (kcat, KM, &#916;H) of enzymatic reactions, even though this application is still underexploited. As heat changes spontaneously occur during enzymatic catalysis, ITC does not require any modification or labeling of the system under analysis and can be performed in solution. Moreover, the method needs little amount of material. These properties make ITC an invaluable, powerful and unique tool to study enzyme kinetics in several applications, such as, for example, drug discovery.
In this work an experimental ITC-based method to quantify kinetics and thermodynamics of enzymatic reactions is thoroughly described. This method is applied to determine kcat and KM of the enzymatic hydrolysis of urea by Canavalia ensiformis (jack bean) urease. Calculation of intrinsic molar enthalpy (&#916;Hint) of the reaction is performed. The values thus obtained are consistent with previous data reported in literature, demonstrating the reliability of the methodology.

Isothermal titration calorimetry measures heat flow released or absorbed in chemical reactions. This method can be used to quantify enzyme-catalysis. In this paper, the protocol for instrumental setup, experiment running, and data analysis is generally described, and applied to the characterization of enzymatic urea hydrolysis by jack bean urease.

Isothermal titration calorimetry (ITC) is a well-described technique that measures the heat released or absorbed during a chemical reaction, using it as ...

Water in Oil Emulsions: A New System for Assembling Water-soluble Chlorophyll-binding Proteins with Hydrophobic Pigments

Chlorophylls (Chls) and bacteriochlorophylls (BChls) are the primary cofactors that carry out photosynthetic light harvesting and electron transport. Their functionality critically depends on their specific organization within large and elaborate multisubunit transmembrane protein complexes. In order to understand at the molecular level how these complexes facilitate solar energy conversion, it is essential to understand protein-pigment, and pigment-pigment interactions, and their effect on excited dynamics. One way of gaining such understanding is by constructing and studying complexes of Chls with simple water-soluble recombinant proteins. However, incorporating the lipophilic Chls and BChls into water-soluble proteins is difficult. Moreover, there is no general method, which could be used for assembly of water-soluble proteins with hydrophobic pigments. Here, we demonstrate a simple and high throughput system based on water-in-oil emulsions, which enables assembly of water-soluble proteins with hydrophobic Chls. The new method was validated by assembling recombinant versions of the water-soluble chlorophyll binding protein of Brassicaceae plants (WSCP) with Chl a. We demonstrate the successful assembly of Chl a using crude lysates of WSCP expressing E. coli cell, which may be used for developing a genetic screen system for novel water-soluble Chl-binding proteins, and for studies of Chl-protein interactions and assembly processes.

This manuscript describes a simple and high-throughput method for assembling water-soluble proteins with hydrophobic pigments that is based on water-in-oil emulsions. We demonstrate the effectiveness of the method in the assembly of native chlorophylls with four variants of recombinant water-soluble-chlorophyll binding proteins (WSCPs) of Brassica plants expressed in E. coli.

Chlorophylls (Chls) and bacteriochlorophylls (BChls) are the primary cofactors that carry out photosynthetic light harvesting and electron transport. ...

A Direct, Early Stage Guanidinylation Protocol for the Synthesis of Complex Aminoguanidine-containing Natural Products

The guanidine functional group, displayed most prominently in the amino acid arginine, one of the fundamental building blocks of life, is an important structural element found in many complex natural products and pharmaceuticals. Owing to the continual discovery of new guanidine-containing natural products and designed small molecules, rapid and efficient guanidinylation methods are of keen interest to synthetic and medicinal organic chemists. Because the nucleophilicity and basicity of guanidines can affect subsequent chemical transformations, traditional, indirect guanidinylation is typically pursued. Indirect methods commonly employ multiple protection steps involving a latent amine precursor, such as an azide, phthalimide, or carbamate. By circumventing these circuitous methods and employing a direct guanidinylation reaction early in the synthetic sequence, it was possible to forge the linear terminal guanidine containing backbone of clavatadine A to realize a short and streamlined synthesis of this potent factor XIa inhibitor. In practice, guanidine hydrochloride is elaborated with a carefully constructed protecting array that is optimized to survive the synthetic steps to come. In the preparation of clavatadine A, direct guanidinylation of a commercially available diamine eliminated two unnecessary steps from its synthesis. Coupled with the wide variety of known guanidine protecting groups, direct guanidinylation evinces a succinct and efficient practicality inherent to methods that find a home in a synthetic chemist&#39;s toolbox.

Here, we present a protocol for direct, early stage guanidinylation that enables rapid total synthesis of aminoguanidine-containing small organic molecules. An advanced synthetic intermediate used in the synthesis of a blood coagulation factor XIa inhibitor was prepared using this protocol.

The guanidine functional group, displayed most prominently in the amino acid arginine, one of the fundamental building blocks of life, is an important ...

In Situ Characterization of Hydrated Proteins in Water by SALVI and ToF-SIMS

This work demonstrates in situ characterization of protein biomolecules in the aqueous solution using the System for Analysis at the Liquid Vacuum Interface (SALVI) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The fibronectin protein film was immobilized on the silicon nitride (SiN) membrane that forms the SALVI detection area. During ToF-SIMS analysis, three modes of analysis were conducted including high spatial resolution mass spectrometry, two-dimensional (2D) imaging, and depth profiling. Mass spectra were acquired in both positive and negative modes. Deionized water was also analyzed as a reference sample. Our results show that the fibronectin film in water has more distinct and stronger water cluster peaks compared to water alone. Characteristic peaks of amino acid fragments are also observable in the hydrated protein ToF-SIMS spectra. These results illustrate that protein molecule adsorption on a surface can be studied dynamically using SALVI and ToF-SIMS in the liquid environment for the first time.

In Situ Characterization of Hydrated Proteins in Water by SALVI and ToF-SIMS

This work presents a protocol for liquid handling and sample introduction to a microchannel for in situ time-of-flight secondary ion mass spectrometry analysis of protein biomolecules in an aqueous solution.

This work demonstrates in situ characterization of protein biomolecules in the aqueous solution using the System for Analysis at the Liquid Vacuum ...

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the development of antibody drug conjugates (ADCs) and nanomedicine, fluorescent microscopy and systems chemistry. For many of these applications, specificity of the bioconjugation method used is of prime concern. The Michael addition of maleimides with cysteine(s) on the target proteins is highly selective and proceeds rapidly under mild conditions, making it one of the most popular methods for protein bioconjugation.
We demonstrate here the modification of the only surface-accessible cysteine residue on yeast cytochrome c with a ruthenium(II) bisterpyridine maleimide. The protein bioconjugation is verified by gel electrophoresis and purified by aqueous-based fast protein liquid chromatography in 27% yield of isolated protein material. Structural characterization with MALDI-TOF MS and UV-Vis is then used to verify that the bioconjugation is successful. The protocol shown here is easily applicable to other cysteine - maleimide coupling of proteins to other proteins, dyes, drugs or polymers.

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry

This protocol details the important steps required for the bioconjugation of a cysteine containing protein to a maleimide, including reagent purification, reaction conditions, bioconjugate purification and bioconjugate characterization.

The chemical linking or bioconjugation of proteins to fluorescent dyes, drugs, polymers and other proteins has a broad range of applications, such as the ...

Laboratory Production of Biofuels and Biochemicals from a Rapeseed Oil through Catalytic Cracking Conversion

The work is based on a reported study which investigates the processability of canola oil (bio-feed) in the presence of bitumen-derived heavy gas oil (HGO) for production of transportation fuels through a fluid catalytic cracking (FCC) route. Cracking experiments are performed with a fully automated reaction unit at a fixed weight hourly space velocity (WHSV) of 8 hr-1, 490-530 &#176;C, and catalyst/oil ratios of 4-12 g/g. When a feed is in contact with catalyst in the fluid-bed reactor, cracking takes place generating gaseous, liquid, and solid products. The vapor produced is condensed and collected in a liquid receiver at -15 &#176;C. The non-condensable effluent is first directed to a vessel and is sent, after homogenization, to an on-line gas chromatograph (GC) for refinery gas analysis. The coke deposited on the catalyst is determined in situ by burning the spent catalyst in air at high temperatures. Levels of CO2 are measured quantitatively via an infrared (IR) cell, and are converted to coke yield. Liquid samples in the receivers are analyzed by GC for simulated distillation to determine the amounts in different boiling ranges, i.e., IBP-221 &#176;C (gasoline), 221-343 &#176;C (light cycle oil), and 343 &#176;C+ (heavy cycle oil). Cracking of a feed containing canola oil generates water, which appears at the bottom of a liquid receiver and on its inner wall. Recovery of water on the wall is achieved through washing with methanol followed by Karl Fischer titration for water content. Basic results reported include conversion (the portion of the feed converted to gas and liquid product with a boiling point below 221 &#176;C, coke, and water, if present) and yields of dry gas (H2-C2's, CO, and CO2), liquefied petroleum gas (C3-C4), gasoline, light cycle oil, heavy cycle oil, coke, and water, if present.

This paper presents an experimental method to produce biofuels and biochemicals from canola oil mixed with a fossil-based feed in the presence of a catalyst at mild temperatures. Gaseous, liquid, and solid products from a reaction unit are quantified and characterized. Conversion and individual product yields are calculated and reported.

The work is based on a reported study which investigates the processability of canola oil (bio-feed) in the presence of bitumen-derived heavy gas oil ...

Synthesis of a Water-soluble Metal&#8211;Organic Complex Array

We demonstrate a method for the synthesis of a water-soluble multimetallic peptidic array containing a predetermined sequence of metal centers such as Ru(II), Pt(II), and Rh(III). The compound, named as a water-soluble metal-organic complex array (WSMOCA), is obtained through 1) the conventional solution-chemistry-based preparation of the corresponding metal complex monomers having a 9-fluorenylmethyloxycarbonyl (Fmoc)-protected amino acid moiety and 2) their sequential coupling together with other water-soluble organic building units on the surface-functionalized polymeric resin by following the procedures originally developed for the solid-phase synthesis of polypeptides, with proper modifications. Traces of reactions determined by mass spectrometric analysis at the representative coupling steps in stage 2 confirm the selective construction of a predetermined sequence of metal centers along with the peptide backbone. The WSMOCA cleaved from the resin at the end of stage 2 has a certain level of solubility in aqueous media dependent on the pH value and/or salt content, which is useful for the purification of the compound.

A potential general method for the synthesis of water-soluble multimetallic peptidic arrays containing a predetermined sequence of metal centers is presented.

We demonstrate a method for the synthesis of a water-soluble multimetallic peptidic array containing a predetermined sequence of metal centers such as ...

Application and Methodology of the Non-destructive 19F Time-domain NMR Technique to Measure the Content in Fluorine-containing Drug Products

Here, we describe a protocol developed by our group that uses low-field fluorine-19 (19F) time-domain (TD) nuclear magnetic resonance (NMR) to measure the average content of fluorinated drugs in their formulated drug product forms: tablets or capsules. This method is specific to fluorinated drugs because it detects only the content of fluorine, avoiding interference from the excipients that lack fluorine. The advantages of measuring the active content of fluorinated drugs using low-field 19F TD-NMR versus high-field 19F solid-state (SS) NMR are the simplicity of the method; the low cost; and the non-destructive nature of the technique, with all samples recoverable in intact forms (e.g., powders, tablets, and capsules), making this technique affordable for any laboratory.
We have tested the method with three fluorinated drug products available on the market - cinacalcet, lansoprazole, and ciprofloxacin - with doses ranging from 15 to 500 mg. The results of the analyses, measured by low-field 19F TD-NMR, supported the reported label claims for the average drug content.
Based on the simplicity and reproducibility of the analysis, we envision this methodology being implemented in any laboratory, including manufacturing plants, as a process analytical technology (PAT) tool in the pharmaceutical industry.

Application and Methodology of the Non-destructive 19F Time-domain NMR Technique to Measure the Content in Fluorine-containing Drug Products

A simple and non-destructive technique that measures the average content of drug substances in formulated drug products containing fluorine using low-field fluorine-19 (19F) time-domain (TD) nuclear magnetic resonance (NMR) is presented here. The technique can be applied to the development and manufacturing of drugs in the pharmaceutical industry.

Here, we describe a protocol developed by our group that uses low-field fluorine-19 (19F) time-domain (TD) nuclear magnetic resonance (NMR) to measure the ...

In Situ Characterization of Boehmite Particles in Water Using Liquid SEM

In situ imaging and elemental analysis of boehmite (AlOOH) particles in water is realized using the System for Analysis at the Liquid Vacuum Interface (SALVI) and Scanning Electron Microscopy (SEM). This paper describes the method and key steps in integrating the vacuum compatible SAVLI to SEM and obtaining secondary electron (SE) images of particles in liquid in high vacuum. Energy dispersive x-ray spectroscopy (EDX) is used to obtain elemental analysis of particles in liquid and control samples including deionized (DI) water only and an empty channel as well. Synthesized boehmite (AlOOH) particles suspended in liquid are used as a model in the liquid SEM illustration. The results demonstrate that the particles can be imaged in the SE mode with good resolution (i.e., 400 nm). The AlOOH EDX spectrum shows significant signal from the aluminum (Al) when compared with the DI water and the empty channel control. In situ liquid SEM is a powerful technique to study particles in liquid with many exciting applications. This procedure aims to provide technical know-how in order to conduct liquid SEM imaging and EDX analysis using SALVI and to reduce potential pitfalls when using this approach.

In Situ Characterization of Boehmite Particles in Water Using Liquid SEM

We present a procedure for real-time imaging and elemental composition analysis of boehmite particles in deionized water by in situ liquid Scanning Electron Microscopy.

In situ imaging and elemental analysis of boehmite (AlOOH) particles in water is realized using the System for Analysis at the Liquid Vacuum Interface ...

Minimum Burning Pressures of Water-based Emulsion Explosives

This manuscript describes a protocol to measure the minimum pressure required for sustained burning of water-based emulsion explosives. Pumping water-based emulsion explosives for blasting applications can be very hazardous, as demonstrated by a number of pump accidents around the globe in the last decades, including some that resulted in fatalities. In Canada, the recognition of this hazard has led to the development of pumping guidelines that were endorsed by both the explosives industry and the Explosive Regulatory Division of the Canadian government. In these guidelines, it was noted that the minimum burning pressures (MBP) measured in a laboratory would provide a good guide to characterize the behaviour of these products in pumping systems. The same guidelines also call for the design of pump systems that prevent, whenever possible, pressures from exceeding the MBP of the product being pumped. At the time of publication of these guidelines, a methodology existed for measuring such MBP values but it had never been validated to measure the MBP of ammonium nitrate water-based emulsions (AWEs). AWEs are now used much more widely than any other water-based explosives and precursors in on-site bulk loading operations.
The Canadian Explosives Research Laboratory (CanmetCERL) has been conducting research over the last ten years to develop a validated testing protocol to measure and interpret representative MBP values for AWEs. The test, as it is performed today, will be described and the critical components will be justified by reference to recent published data. Results of MBP measurements, for a range of AWE products, will be presented. Inclusion of the MBP test in the test standards for the authorization of high explosives in Canada will also be discussed.

We present an apparatus based on hot-wire ignition in a pressurized enclosure and an associated methodology to measure the minimum pressure required to induce sustained combustion in water-based emulsion explosives. This method improves product characterization to allow one to use them more safely during pumping and mixing operations.