Terpenoids are chemically lipid-soluble compounds and they can be extracted with petroleum ether generally. Sesquiterpene lactones, diterpenes and less polar triterpenoids extraction can be also performed by using benzene, ether and chloroform. Ethyl acetate and acetone extracts contain oxygenated diterpenoids and triterpenoids. Ethanol, methanol and water led to the extraction of highly oxygenated namely polar triterpenes as well as triterpenoid and sterol glycosides. Total extraction of the material carried out by any polar solvents such as acetone, aqueous methanol and ethanol and then re-extraction with hexane, chloroform and ethyl acetate is also leads to successive extraction of terpenoids and sterols. Isolation for mono- as well as sesquiterpenoids can be achieved through extraction with non-polar solvents such as petroleum ether, ether and hexane can be preferred due to artifact formation at the raised temperatures. Adsorbtion chromatography on silica gel is the simplest and most effective method for separation of terpenoids and GLC is used commonly for identification as well as isolation of the monoterpenoids. Column chromatography is also a valid method for fractionation of monoterpenoids. Isocratic elutions with solvents such as pentane, petroleum ether, hexane or gradient elution with mixtures of solvents in increasing polarity leads to successive isolation. Additionally, faster techniques of column chromatography such as flash chromatography may be preferred due to conventional column chromatography for separating procedure is time-consuming and frequently gives poor recovery owing to band tailing. Isolation of the mono- and sesquiterpenoids is also achieved by preparative GLC currently. For isolation of various terpenoids especially sesqui-, di-, tri- and tetraterpenoids, column chromatography is convenient method. As stationary phase silica gel, alumina, cellulose, sephadex, polyamid are used for the separation of different types of secondary metabolites but of this silica gel is the most extensively used adsorbent for particularly nonpolar and medium polar compounds including terpenoids. Silver nitrate impregnated silica gel is also provide separation of terpenoids containing unsaturation. Terpenoids are generally alicyclic compounds and isomerism is common. Due to the twisted cyclohexane ring, in chair form, different geometric conformations are possible depending on the substitution around the ring. Therefore, stereochemistry is commonly found in terpenoids. These structural features may cause artifact formation during isolation procedure.
First make unsaponifiable matter from your petroleum ether extract and then run the column using gradient elution technology.
Terpenoids are chemically lipid-soluble compounds and they can be extracted with petroleum ether generally. Sesquiterpene lactones, diterpenes and less polar triterpenoids extraction can be also performed by using benzene, ether and chloroform. Ethyl acetate and acetone extracts contain oxygenated diterpenoids and triterpenoids. Ethanol, methanol and water led to the extraction of highly oxygenated namely polar triterpenes as well as triterpenoid and sterol glycosides. Total extraction of the material carried out by any polar solvents such as acetone, aqueous methanol and ethanol and then re-extraction with hexane, chloroform and ethyl acetate is also leads to successive extraction of terpenoids and sterols. Isolation for mono- as well as sesquiterpenoids can be achieved through extraction with non-polar solvents such as petroleum ether, ether and hexane can be preferred due to artifact formation at the raised temperatures. Adsorbtion chromatography on silica gel is the simplest and most effective method for separation of terpenoids and GLC is used commonly for identification as well as isolation of the monoterpenoids. Column chromatography is also a valid method for fractionation of monoterpenoids. Isocratic elutions with solvents such as pentane, petroleum ether, hexane or gradient elution with mixtures of solvents in increasing polarity leads to successive isolation. Additionally, faster techniques of column chromatography such as flash chromatography may be preferred due to conventional column chromatography for separating procedure is time-consuming and frequently gives poor recovery owing to band tailing. Isolation of the mono- and sesquiterpenoids is also achieved by preparative GLC currently. For isolation of various terpenoids especially sesqui-, di-, tri- and tetraterpenoids, column chromatography is convenient method. As stationary phase silica gel, alumina, cellulose, sephadex, polyamid are used for the separation of different types of secondary metabolites but of this silica gel is the most extensively used adsorbent for particularly nonpolar and medium polar compounds including terpenoids. Silver nitrate impregnated silica gel is also provide separation of terpenoids containing unsaturation. Terpenoids are generally alicyclic compounds and isomerism is common. Due to the twisted cyclohexane ring, in chair form, different geometric conformations are possible depending on the substitution around the ring. Therefore, stereochemistry is commonly found in terpenoids. These structural features may cause artifact formation during isolation procedure.
1. Check the petroleum fraction with hexane/ethyl acetate with increasing polarity (step gradient)
2. Follow the same method using column
3. Try using Preparative TLC
Terpenoids are non-polar compound. They can be extracted with petroleum ether. The triterpene structure have two parts of polarity with hydroxy group (OH) normally at the carbon position C3 and non-polarity part of metylene (-CH2), methine (-CH), methyl (-CH3) with the total 30 carbons; non-polar part of the carbon blackbone for a triterpene molecule. The petroleum ether extracted many groups of triterpene in the nature with the same polarity or less but some of triterpene group with the high polarity can not extracted with the petroleum ether.
I agree with Mr. Yogesh Tripathi. I think he is an expert in Terpenoid separation
Dissolve the crude in water. By this method water soluble impurities will be removed. Then hexane/ethyl acetate step gradient elution is suitable for isolation.
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