K. V. N. S. Srinivas

Phenolics from needles of himalayan Taxus baccata

Chemical investigation on the needles of the Himalayan yew, Taxus baccata, has resulted in the isolation of several phenolic compounds including 3-demethyl-(−)-secoisolariciresinol, a new lignan, and taxuside, a new phenolic glucoside. The structures of the new compounds were derived from their spectral data and chemical transformations.

Stereochemistry of 4-aryl-2-butanols from himalayan Taxus baccata

Abstract 4-(4′-Hydroxyphenyl)-2 R -butanol, 4-(3′,4′-dihydroxyphenyl)-2 R -butanol and 4-(3′-methoxy-4′-hydroxy- phenyl)-2 R -butanol have been isolated from the needles of Himalayan Taxus baccata . These two compounds have not previously been reported in stereospecific forms. Their stereochemistry has been determined by enzymatic reduction of their corresponding 2-butanones.

CONVERSION OF BERBERINE INTO BERBERRUBINE BY SELECTIVE DEMETHYLATION UNDER MICROWAVE IRRADIATION[1]

ABSTRACT Berberine, a natural alkaloid, underwent selective demethylation under microwave irradiation to form an important bioactive compound, berberrubine in excellent yield.

Jatrodien, a lignan from stems of Jatropha gossypifolia☆☆☆

A novel lignan, jatrodien, representing an intermediate in Haworths biosynthetic scheme for the formation of lignans, has been isolated from the stems of Jatropha gossypifolia. The structure of the compound was derived from its spectroscopic data. Synthesis of the compound, starting from piperonal has been achieved.

Minor C29-steroids from the marine red alga, Gracilaria edulis

Abstract Four minor C 29 -steroids, poriferast-5-en-3β-ol (clionasterol), 3β-hydroxyporiferast-5-en-7-one, poriferast-5-en-3β,7α-diol and poriferasta-3,5-diene-7-one were isolated from the marine red alga, Gracilaria edulis . This is the first report of the characterization of the last three compounds from a natural source and of the first compound from a species of Gracilaria .

A lignan from needles of Himalayan Taxus baccata

Abstract A new lignan, 4- O -methyl-3′- O -demethyl-(-)-secoisolariciresinol, has been isolated from the needles of Himalayan yew, Taxus baccata . The structure of the compound was established from its spectral data and chemical reactions.

Stereospecific synthesis and absolute configuration of (+)-rhododendrol☆

Abstract The stereospecific synthesis of (+)-rhododendrol, a constituent of Rhododendron maximum and Acer nikoense , by enzymatic reduction of4-(4′-hydroxyphenyl)-2-butanone has shown that the absolute configuration of the molecule is S .

Dihydroxysterols from the marine red alga, Gracilaria edulis☆☆☆

Abstract Two minor C 29 dihydroxysteroids, poriferast-5-en-3β,7β-diol and 5α-poriferastane-3β,6α-diol have been isolated from the chloroform extract of the marine red alga, Gracilaria edulis .

Lignans, biflavones and taxoids from Himalayan Taxus baccata

Abstract Chemical investigation of the twigs (separated from the needles) of the Himalayan yew, Taxus baccata , has culminated in the isolation of a new lignan, 4′- O -demethylsuchilactone, along with eight phenolic compounds, (−)-rhododendrol, (−)-rhododendrin, sciadopytisin, ginkgetin, kayaflavone, (−)-secoisolariciresinol, suchilactone and a lignan diol, not previously encountered in nature. Three taxoids, brevifoliol, 13-decinnamoyltaxchinin B and 10-deacetylbaccatin III were also isolated. This is the first report on the phytoconstituents isolated only from the twigs of the Himalayan yew.

A taxoid from needles of Himalayan Taxus baccata

13-Acetyl-13-decinnamoyltaxchinin B, a taxoid having a rearranged 11(15 → 1)abeo-taxane skeleton, has been isolated from the needles of the Himalayan yew, Taxus baccata. The compound has not previously been encountered in nature. Its structure was established by 1- and 2D NMR techniques including DQF-COSY, HETCOR and HMBC experiments. The conversion of 13-decinnamoyltaxchinin B, a known taxoid, to 13-acetyl 13-decinnamoyltaxchinin B confirmed the structure of the latter.