Binayak Das

Swertane triterpenoids from Swertia chirata

Abstract Two novel triterpenes belonging to swertane skeleton, besides gammacer-16-en-3β-ol and 21α H -hop- 22(29)-en-3β-ol, of rare occurrence have been isolated from Swertia chirata , along with some common triterpenoids. Their structures were established on the basis of spectral and chemical evidence.

A diterpenoid from roots of Gelonium multiflorum

Abstract A new diterpene diol, along with the three known flavones, kanugin, desmethoxy kanugin and pinnatin, was isolated from the roots of Gelonium multiflorum and its structure was established as ent -kaurene-3β, 15β-diol mainly on the basis of 2D NMR spectral analyses.

Triterpenoid prosaponins from leaves of Maesa chisia var. angustifolia

Abstract Acid hydrolysis of the saponin fraction of the leaves of Maesa chisia var. angustifolia yielded a monoglucoside fraction besides camelliagenin A as a minor constituent. The glucose moiety of the former could be removed by hydrolysis by Smith degradation to yield two new acylated triterpenoids characterised as 16α- O -acetyl-22α- O -angeloyl-camelliagen A and 16α- O -acetyl-22α- O -(2′-methylbutyroyl)-camelliagenin A as well as camelliagenin A and its 22α,28-glycolaldehyde acetal. The possibility of the later acetal derivative being an artefact could not, however, be ruled out.

Solanolide, a steroid lactone sapogenin from Solanum hispidum☆

Abstract Solanolide, a new C 22 steroid lactone sapogenin isolated from the leaves of Solanum hispidum Pers., has been characterized as 3β, 6α, 16β-trihydroxy-5α-pregnane-20 S -carboxylic acid (22, 16)-lactone from 1 H and 13 C NMR analyses and correlation with neochlorogenin.

Peracid oxidation products of swertanone, the novel triterpene of Swertia chirata

Abstract While treatment of swertanone (1a) with mineral acids and Lewis acids yielded isoswertanone (2a) as the only isolable product, its reaction with m -chloroperbenzoic acid afforded 7α ,8α -epoxyswertanone (7), 7α -hydroxy-swert-8-en-3-one (8), swerta-7,9(11)-dien-3-one (3a), its 7α ,8α -epoxide (4a), 7α -hydroxy-friedogammacer-14-en-3-one (5a) and its 14α ,15α -epoxide (6a). The structures of the products have been elucidated mainly on the basis of 1H and 13C NMR spectroscopy and, in some cases, by chemical correlation. Assignments of 13C NMR signals of the products have been done and those of some of the signals of 1a, swertenyl acetate (1b) and swertenol (16) have been revised. In this connection, spectra of bauerenyl acetate (18), isobauerenyl acetate (19) and multiflorenyl acetate (20) have been recorded.

Tetracyclic triterpenoids from Glycosmis arborea

Abstract Two new tetracyclic triterpene alcohols, along with (24 S )-24-methyl-5 α -lanosta-9(11),25-dien-3 β -ol and 24,24-dimethyl-5α-lanosta-9(11),25-dien-3β-ol, were isolated from the petrol extract of the overground part of Glycosmis arborea and their structures were elucidated to be (24 S )-24-methyl-5 α -lanosta-9(11),25-dien-3 α -ol and 24,24-dimethyl-5α-lanosta-9(11),25-dien-3α-ol on the basis of 2D NMR and mass spectral analyses.

Studies on Indian medicinal plants. Part 77. Structure and stereochemistry of some new steroidal alkaloids from Solanum pseudocapsicum and Solanum giganteum by nuclear magnetic resonance spectroscopy

Three new stereoisomeric Steroidal alkaloids, viz. solacapine (6), episolacapine (11), and isosolacapine (13), along with another hitherto unreported base, O-methylsolanocapsine (3), have been isolated from the arboreal part of Solanum pseudocapsicum Linn. They have been characterised as (20S, 22R, 23S, 25R)-, (20S, 22R, 23R, 25R)-, and (20S, 22S, 23S, 25R)-3β-amino-16α,23-dihydroxy-22,26-epimino-5α-cholestanes, respectively, primarily based on 1H and 13C n.m.r. spectra. The structures of (3), (6), and (11) could be confirmed by correlation with solanocapsine (1). Isosolacapine (13) turned out to be the first 22,26-epiminocholestane derivative encountered in nature with 22βN stereochemistry. A diagnostic down-field shift of the C-22 resonance frequency in the 13C n.m.r. spectra of 22βN-22,26-epiminocholestanes by ca. 3 p.p.m. relative to those of the corresponding 22αN-isomers has been observed. The C-25 stereochemistry of solanogantamine (28) and isosolanogantamine (29), the stereoisomeric 3-amino solanidanes isolated from Solanum gigantem Jacq., has also been established.

Peracid induced oxidative rearrangements of triterpenoids: Products of new skeleton from bauerenyl acetate

Abstract Treatment of bauerenyl acetate (2) with m-chloroperbenzoic acid at 4 °C yielded the migrated products, viz. 7α-hydroxy-14,27-cycloisoursan-3β-yl acetate (9) and its 15α-hydroxy derivative (12) belonging to a new skeleton, 7α-hydroxyisours-14-en-3β-yl acetate (10) and 14α,15α-epoxy-7α-hydroxyisoursan-3β-yl acetate (11), besides 7α,8α-epoxybaueran-3β-yl acetate (3), bauera-7,9(11)-dien-3β-yl acetate (4), bauera-6,8-dien-3β-yl acetate (5), 7α,8α-epoxybauer-9(11)-en-3β-yl acetate (6), 7α,8α,9α,11α-diepoxybaueran-3β-yl acetate (7) and 8α,9α-epoxy-7α-hydroxybaueran-3β-yl acetate (8). The structures of all the products were elucidated mainly on the basis of 2D NMR spectral analyses. The 1H and 13C chemical shifts of bauerenyl acetate (2) and its reaction products (3–12) were assigned unambiguously.

Juripidine, a 3-amino steroidal alkaloid from roots of Solanum hispidum☆

Abstract A new steroidal alkaloid designated as juripidine, together with jurubidine, has been isolated from the roots of Solanum hispidum and purified as its acetate. Its structure has been elucidated as (25 S )-3β-amino-5α-spirostan-6α-ol by physical methods and by correlation with neochlorogenin.

X-Ray crystal structure of swertanone, a triterpene of new skeletal type from Swertia chirata Buch.-Ham.

The structure and stereochemistry of swertanone, a triterpene with a new skeletal type isolated from Swertia chirata, have been established from spectral data and single-crystal X-ray analysis.