Essential oil identification and estimation of its quality is an important and integral process of its qualitative analysis. Their high economic value and extensive usage by various industries help in ensuring its quality, which is a significant aspect of its quality control. Today GC is an invaluable tool in the identification of essential oils. A…
Volatile oils are traditionally obtained by distillation of the plant parts containing the oil. Some volatile oils which undergo undesirable changes in the oil composition and organoleptic features due to distillation are separated by methods not involving heat application. In addition to these several newer methods such as super critical fluid extraction may now be…
Volatile oils are defined as oily liquids, which are entirely or almost entirely volatile without decomposition. They are also called essential oils as they are said to represent the essence of the odor constituents of the plants from which they are obtained. Volatile oils have been used in medicine, perfumery, and for flavoring since ancient…
Formation of persistent foams during plant extraction and concentration is a good indicator for the presence of saponins in the plant tissue.
As saponins occur as complex mixtures their isolation in a state of purity is somewhat tedious. In general, various chromatographic techniques are employed for their isolation and acetylation renders them crystallizable. Different extraction procedures are followed depending on the nature of saponin, amount present, and nature of the plant tissue. For the isolation of steroidal…
Saponins are high molecular weight, high polarity compounds which on hydrolysis yield, sugars, uronic acids, and steroidal or pentacyclic triterpenoid aglycones. Both have C-3 sugar linkage and have a common biogenetic origin. Many saponins have an additional sugar at C26 or C28 position. Natural sapogenins differ in their configuration at C-3, C-5, and C-25 positions…
Saponins are high molecular weight, foam-forming glycosides based on the tetracyclic (steroidal) and pentacyclic tritepene groups and are characterized by their property of producing frothing aqueous solutions even at very low concentrations. Detected in over 70 plant families, saponins occur as complex mixtures of glycosides, differing from one another in nature of sugar attachment or…
Typically coloured anthocyanins are detected in aqueous alcoholic solutions by red to blue colour pigmentation. Flavones and flavonols are readily detected in white or pale yellow tissues by the appearance of yellow or red colours when the tissue is exposed to ammonia. In general, solutions containing flavonoids change colour when treated with alkali. Following are…
No single extraction procedure is ideally suited for all flavonoids due to the differences in their solubility characteristics. Also when the class of flavonoid present in the plant material is not known, a preliminary TLC examination of the hydrolyzed plant extract is essential in order to determine this. Chromatographic separation of the flavonoid rich fraction…
Most flavonoids are coloured in crystalline masses and faintly coloured or colourless in microgram quantities. Anthocyanins, chalcones, and aurones possess deep colours even in trace amounts. In general, flavonoids are coloured, water-soluble compounds insoluble in organic solvents, while non glycosidic flavonoids are sparingly soluble in water and soluble in ether. They range in complexity from…