BIOSYNTHESIS OF STEROLS IN INSECTS ..
Terpenoids: Terpenoids are derived from five carbon isoprene units that are assembled in numerous combinations to generate vast arrays of terpene derivatives, collectively referred to as isopreniods. Most terpenoids are present in the glycosidic form rather than the non-polar or low polarity terpene aglycone form (). The terpenoids encompasses other classes of bioactive principles in diverse collections of plants. Notable examples include: mono- and sesquiterpene volatile derivatives from (), mono- and sesquiterpenes from (), saponins and sapogenins from (), sesquiterpene lactones from() tetraterpene carotenoids from (), triterpenoids from (; ) and β-sitosterol; a triterpene-like compound from () that exhibits plasma cholesterol lowering properties.
The Biosynthesis of Hepatic Cholesterol Esters and ..
Extraction of plant materials: For scientific evaluations of s, extraction of bioactive principles from the plant material is crucial in order to obtain the desired chemical components from the plant materials for separation and characterization. Analytical extraction ensures that potential active constituents are not lost, distorted or destroyed during the preparation of the extract from plant samples. Plant materials are commonly extracted by means of liquid solvents in what is known as the solid-liquid solvent extraction. A typical solid-liquid solvent extraction process for plant materials involve drying and grinding of the plant material, choosing a suitable extraction solvent and extraction procedure ().
These side chainshave been isolated with such unusual features as quaternary alkyl groups,cyclopropane and cyclopropene rings, allenes, and even acetylenes ().
24-Isopropylcholesterol is abundant and characteristic (with its analogueunsaturated at C22-C23) of the class Demospongiae.
Biosynthesis of Cholesterol and Other Sterols
The recent development of cost-effective, sustainable and well-controlled application of technology such as regeneration and genetic transformation/enhancement of s serve to boost the selective mass production of bioactive principles (; ; ). The technology is an advantage in that it provides continuous, reliable source of plant pharmaceuticals and a platform for large scale plant from which bioactive principles could be harvested.
Cholesterol biosynthesis - SlideShare
We conclude that AtSAT1 mediates phytosterol ester biosynthesis, alternative to the route previously described for phospholipid:sterol acyltransferase, and provides the molecular basis for modification of phytosterol ester level in seeds.
Sterol biosynthesis is complex and involves at least 25 ..
The choice of the extraction solvent depends mainly on the polarity and solubility of the bioactive principle of interest. Although water is generally used in many traditional herbal extraction protocols, organic solvents of varying polarities are often exploited to obtain bioactive principles of varying polarities and solubilities. The choice of extraction procedure depends on the nature of the source material and the compound to be isolated. Conventional solvent extraction procedures applicable to plant natural products include, but not limited to the use of maceration, heating under reflux, sonification, percolation, soxhlet extraction, steam distillation and sequential solvent extraction. Contemporary extraction techniques include ultrasound, solid-phase micro-extraction, supercritical-fluid extraction, pressurized-liquid extraction, microwave-assisted extraction, solid-phase extraction and surfactant mediated techniques (; ; ; ). The efficiencies of conventional and contemporary extraction methods mostly depend on the critical input parameters; understanding the nature of plant matrix; chemistry of bioactive principles and scientific expertise (). The polarity of commonly used extraction solvents and chemical profiles of the extracts are summarized in .
Methods and compositions for inhibiting sterol biosynthesis
The original structure of gorgosterol,which bears an unusual C-23 methyl group and a cyclopropane ring in the sidechain contributed greatly to the renewed interest in marine sterols.