The biosynthesis of phytosterols and steroidal sapogenins has been reviewed due to its relevance to the possible mechanisms of increase in sapogenin yield from fenugreek seed. The components of the seed, especially diosgenin and yamogenin, are given together with physico-chemical data for these two compounds isolated by preparative-TLC. The determination of diosgenin and yamogenin by infrared spectrophotometry was based previously upon calibrations using diosgenin and sarsasapogenin, due to the difficulty of isolating yamogenin. This difficulty has been overcome by the design of a preparative-TLC tank utilizing continuous elution. The pure diosgenin and yamogenin obtained have been used to make a detailed study of the calibrations required for the accurate determination by infrared analysis, of these two epimers when mixed together in any proportion. Recommendations for the calibrations show important changes from those previously used with sarsasapogenin. The routine procedure widely used for the extraction of steroidal sapogenins from plant materials yielded an extract from fenugreek seed that, contrary to previous data, was unsuitable for the direct determination of diosgenin and yamogenin by infrared analysis. A column chromatographic procedure was devised which was capable of isolating diosgenin and yamogenin from the crude extracts, suitable for infrared analysis. The apparatus designed for this chromatography permits the simultaneous development of twelve columns, the quantitative collection in pre-determined volumes, of various fractions of the crude extract, and statistical analysis has shown that each column may be used at least five times without re-packing. A method of sterol analysis by gas chromatography is described. The procedures described have been used for the quantitative study of diosgenin, yamogenin, sitosterol and other sterols present in the seed of fenugreek. Changes in the levels of these compounds following seed exposure to conditions that inhibit or encourage germination have been investigated and are discussed. The effect of riboflavine, squalene, geraniol, kinetin and Atromid-S when present during the above conditions, upon the yields of diosgenin and yamogenin, have received statistical analysis. The behaviour and changes in sapogenin yields of four varieties of seed during the early stages of germination have been studied, including their method of water imbibition, and the results support other evidence that the four varieties are distinctly different. Recommendations are given that enable the maximum yield of sapogenin to be extracted from each variety.
|Date of Award||1973|