Salimuzzaman Siddiqui

Fully acetylated carbamate and hypotensive thiocarbamate glycosides from Moringa oleifera

Six new and three synthetically known glycosides have been isolated from the leaves of Moringa oleifera, employing a bioassay-directed isolation method on the ethanolic extract. Most of these compounds, bearing thiocarbamate, carbamate or nitrile groups, are fully acetylated glycosides, which are very rare in nature. Elucidation of the structures was made using chemical and spectroscopic methods, including 2D NMR techniques. Thiocarbamates showed hypotensive activity.

PENTACYCLIC TRITERPENOIDS FROM LANTANA CAMARA

Abstract Seven pentacyclic triterpeonoids, camarinic acid, camaric acid, oleanolic acid, pomolic acid, lantanolic acid, lantanilic acid and lantic acid, have been isolated from the aerial parts of Lantana camara . The two new constituents, camarinic acid and camaric acid, have been characterized as 22β-acetoxy-3,25-epoxy-3α-hydroxy-12-ursen-28-oic acid and 3,25-epoxy-3 α -hydroxy-22 β (2-methyl-2 Z -butenoyloxy)-12-oleanen-28-oic acid, respectively. The structures of the new acids and lantanilic acid have been elucidated through extensive 1D and 2D NMR studies (COSY-45, NOESY, J -resolved, hetero-COSY), while those of the remainder rest on comparisons of their spectral data with the values reported in the literature.

Studies on the constituents of the leaves of Nerium oleander on behavior pattern in mice

Fresh, undried and uncrushed leaves of Nerium oleander were subjected to methanol extraction and bioassay directed fractionation. This led to the isolation of two purified fractions namely, B-1 and B-3. Fractions B-1 and B-3 were studied with respect to their actions on the central nervous system and behavior pattern in mice. Both fractions were found to produce reduction in locomotor activity, rota rod performance and potentiation of hexobarbital sleeping time. These fractions also showed analgesic activity. When tested against picrotoxin induced convulsions fraction B-1 showed 40% protection, while fraction B-3 exhibited 60% protection against bicuculline induced convulsions. These findings suggest that both fractions possess a CNS depressant action.

Triterpenoids and phenanthrenes from leaves of Bryophyllum pinnatum

Abstract From fresh leaves of Bryophyllum pinnatum three new constituents, bryophyllol, bryophollone and bryophollenone have been isolated and their structures elucidated by spectral and chemical studies. Three new compounds, bryophynol and two phenanthrene derivatives have also been identified in the mixture. 18α-Oleanane, ψ-taraxasterol, β-arnyrin acetate and a new sterol, reported earlier as a hydrolysed product, have also been obtained, along with a mixture of α- and β-amyrins and their acetates.

Novel hypotensive agents, niazimin A, niazimin B, Niazicin A and Niazicin B from Moringa oleifera: isolation of first naturally occurring carbamates

Two novel hypotensive carbamate glycosides designated niazimin A 1 and niazimin B 3 and two new hypotensive mustard oil glycosides possessing the thiocarbamate group, niazicin A 5 and niazicin B 10 along with a benzaldehyde glycoside 12 have been isolated from the fresh leaves extract of Moringa oleifera employing bioassay-guided fractionation. The structures of all these glycosides have been elucidated on the basis of spectroscopic evidence (IR, UV, MS, NMR, 2D NMR) and chemical reactions. Compounds 1 and 3 appear to be the first natural products embodying the carbamate moiety. The amide bond in these compounds appears to play an important role in the hypotensive activity, since in both the carbamates and thiocarbamates it is common to those which possess hypotensive activity.

Study of the in vitro antimicrobial activity of harmine, harmaline and their derivatives

Peganum harmala L. (Zygophyllaceae), commonly known as harmal, grows wild in the semiarid regions of IndoPakistan subcontinent, Iran and Africa. Its different parts have been used in traditional systems of medicine for the treatment of a variety of human ailments (Dymock et al., 1890; Chopra et al, 1956). Peganum harmala is known to contain four main alkaloids, namely harmaline (Ci3Hi40N2) reported by Goebel, harmine (Ci3H120N2) isolated by Fritsche, harmalol (Ci2Hi20NZ) noted by Goebel and prepared by Fischer from harmaline, and peganine (C,,Hi20Nz) obtained by Merk and later found to be identical with vasicine isolated earlier by Hooper (Henry, 1949). Harmal alkaloids have been reported to possess hypotensive activity (Codding, 1983), while earlier the seeds have been shown to have a marked physiological activity (Elger, 1928) and have been used for curative purposes (El-Saad and EI-Rifaie, 1980). Preliminary work on the antimicrobial study of the crude ethanolic extract of seeds of Peganum harmala was perfomed by different groups of workers (Ross et al., 1980; Al-Sharma and co-

Two cytotoxic pentacyclic triterpenoids from Nerium oleander

The isolation and structure elucidation of two novel cytotoxic pentacyclic triterpenoids cis-karenin (3β-hydroxy-28-Z-p-coumaroyloxy-urs-12-en-27-oic acid) and trans-karenin (3-β-hydroxy-28-E-p-coumaroyloxy-urs-12-en-27-oic acid) from the leaves of Nerium oleander is described.

Isolation and structure of two cardiac glycosides from the leaves of Nerium oleander

Abstract Two new cardiac glycosides, kaneroside and neriumoside, have been isolated from the fresh, undried, winter leaves of Nerium oleander and their structures established as 3β- O -( D -diginosyl)-2α-hydroxy-8,14β-epoxy-5β-carda-16:17,20:22-dienolide and 3β- O -( D -diginosyl)-2α,14β-dihydroxy-5β-carda-16:17,20:22-dienolide, respectively, through chemical and spectral studies.

Isolation and structure elucidation of novel hypotensive agents, niazinin A, niazinin B, niazimicin and niaziminin A + B from Moringa oleifera: the first naturally occurring thiocarbamates

Novel hypotensive principles, niazinin A 1, niazinin B 2, niazimicin 4 and niaziminin A and B 6+7, have been obtained from the ethanolic extract of the fresh leaves of Moringa oleifera, employing a bioassay-guided isolation procedure. Their structures have been elucidated through spectroscopic (including 2D NMR techniques) and chemical methods. These compounds are mustard oil glycosides which are very rare in Nature and are also the first examples of naturally occurring thiocarbamates.

Terpenoids from the stem bark of Azadirachta indica

Abstract Two new isomeric diterpenoids nimbinone and nimbinone and a new ring C- seco -tetranortriterpenoid isonimbinolide have been isolated from the stem ba