Showing papers by "Kalpattu K. Balasubramanian published in 1999"

Enhancement of β-Glucosidase and β-Galactosidase of Trigonella foenum-graecum by Exposure to the Allelochemical Mimosine

Abstract: Glycohydrolases assume significance in the metabolism of biological systems and have important industrial applications in the areas of pharmaceuticals, food, and medicine. Glycosidases were screened in germinating seeds, and attempts were made to enhance their levels. Screening of glycosidases in the seedlings during a 72 h germination period revealed higher levels of β-glucosidase and β-galactosidase in Trigonella foenum-graecum compared to Cicer arietinum and Vigna radiata. Activity of β-galactosidase was in general higher than that of β-glucosidase in all the seedlings tested. During growth, exposure of the seedlings to an allelochemical, mimosine, at 0.1 mM resulted in the enhancement of enzyme levels by 50% in the seedlings of T. foenum-graecum, whereas the addition of mimosine to the assay medium in vitro did not affect the enzyme activities. Hydrolytic activity was enhanced by addition of glycerol in the medium up to 0.1 M in the case of β-glucosidase and with 0.05 M in the case of β-galactosidase. In general, the hydrolytic rate was higher by about 30% in the seedlings exposed to mimosine compared to that of the control. Concomitant enhancement in the rates of transgalactosidation by 51% and transglucosidation by 23% was also noted, underscoring the relevance of plant glycohydrolases for appropriate applications.

Mild and Efficient Tetrahydropyranylation of Alcohols — Catalysis by Lithium Perchlorate in Diethyl Ether.

Abstract: Treatment of 3,4-dihydro-2 H -pyran 1 with various alcohols 2 – 10 furnished the tetrahydropyranyl ethers 11 – 19 in the presence of 5 M lithium perchlorate in diethyl ether (5 M LPDE), which is essentially a neutral medium.

Synthesis of 2,3‐Unsaturated Thioglycopyranosides Mediated by Lithium Tetrafluoroborate.

Abstract: Treatment of tri-O acetyl-D-glucal 1 with diverse thiols 2–7 in the presence of LiBF4 in CH3CN, furnished aryl/alkyl 2,3-unsaturated thioglycopyranosides 8–13 (56–72%).