Biomedical subjects
Publications and source records attributed to V U Ahmad.
The antibacterial and antifungal activities, along with a phytotoxicity test of the newly isolated diterpene bondenolide (1), of a methanol extract, ethylacetate fraction and water soluble part of the methanol extract of Caesalpinia bonduc (L.) Roxb. were assayed.
Four known coumarins, coumarin (1), 7-hydroxy-3-methylcoumarin (2), oreoselone (3) and heraclenin (4), were isolated from aerial part of Halocnemum strobilaceum. Their structures were determined by 1 and 2-D NMR techniques.
Polysaccharides extracted from seeds of Libyan dates with hot ethanol 80% (FI) and 0.1 M phosphate solution (FII) were fractionated and purified by ion-exchange and gel-filtration chromatography. According to methylation and hydrolysis analysis, the main chains of FI and FII consisted of (1-->4)-linked glucomannan; only traces of branched sugar residues were detected. This is the first report on the isolation of glucomannan from date seeds.
The crystal structure of caulerpin (dimethyl 6,13-dihydrodibenzo[b,i]phenazine-5,12-dicarboxylate, C(24)H(18)N(2)O(4)), an indole alkaloid, reported in space group Cc with an acute beta angle, has been redetermined in the correct space group, C2/c. The molecule has twofold crystallographic symmetry and is composed of two essentially planar indole groups fused to an eight-membered cyclooctatetraene ring which adopts a boat conformation. The molecular dimensions are normal. The structure is stabilized by intermolecular and intramolecular interactions involving the indole N-H atom and carbonyl O atom [N.O 3.211 (4) and 2.836 (4) A].
The hexane soluble part of Zataria multiflora afforded three new aromatic constituents which include two p-cymene derivatives: multiflotriol (1), multiflorol (2) and an aromatic ester of p-hydroxy benzoic acid (3). In addition to these three new compounds, three known compounds, dihydroxyaromadendrane, luteolin and alpha-tocopherolquinone, have also been isolated for the first time from the same source. The structures of all the isolated constituents were elucidated by means of spectroscopic methods including 2D-NMR techniques.
The isolation and NMR spectra of otosenine (1) and seneciphylline (2) from Senecio lorenthii are reported.
Four known flavonoids were isolated from the aerial parts of Salvia moorcroftiana.
The isolation and characterization of calonysterone (1), blechnoside B (2), 20-hydroxyecdysone and isovanillin from the whole plant of Asparagus dumosus are being reported for the first time from this source.
Two new diterpenoids, trilobic acid (1) and trilobiol (2), have been isolated from the methanolic extract of Salvia triloba. Their structures were elucidated with the aid of NMR spectroscopy including two-dimensional-NMR techniques.
A new guaianolide, taraxacin (1), and a known sesquiterpene ketolactone (2) have been isolated from an ethyl acetate-soluble part of a methanolic extract of Taraxacum wallichii. The structure of 1 was established using NMR, MS, and X-ray crystallographic methods. The (13)C NMR data of 2 is also being reported for the first time.
Two novel bidesmosidic cycloartane-type glycosides, depressosides C and D were isolated from Corchorus depressus L. Their structures were elucidated as (22R)-16beta,22-epoxy-3beta,26-dihydroxy-9,19-cyclolanost-++ +24E-ene 3, 26-di-O-beta-D-glucopyranoside and (22R,24S)-22,25-epoxy-3beta,16beta,24-trihydroxy-9,19-cyclolano stane 3, 24-di-O-beta-glucopyranoside, respectively on the basis of chemical evidence and detailed spectroscopic studies.
A total of 22 ethanol extracts of seaweed species (13 brown, 6 green and 3 red) collected from the Karachi coast were investigated for brine shrimp cytotoxicity. Of all the species, only six namely Stoechospermum marginatum, Sargassum swartzii, S. binderi, Spatoglossum asperum, Stokeyia indica (brown) and Caulerpa racemosa (green) showed significant activity. n-Hexane-soluble fractions of the ethanol extract of S. marginatum and S. swartzii were found to be responsible for the activity, whereas the methanol-soluble fractions of S. asperum and S. binderi were most active. The water extract of S. indica and C. racemosa exhibited the most prominent activity (LC50 value below 70 micrograms/mL) when compared with the ethanol extracts and their fractions. Cytotoxic activity may be due to the compounds differing in polarity.
A new steroidal saponin, dumoside, characterized as (20S)-3 beta, 16 beta-dihydroxy pregn-5-ene-22-carboxylic acid (22, 16)-lactone-3-O-beta-chacotrioside, was isolated from the whole plant of Asparagus dumosus Baker and the structure was deduced from spectral data. In addition to dumoside three more steroidal saponins characterized as 3 beta-dihydroxy pregn-5,16-dien-20-one 3-O-beta-chacotrioside, 3 beta, 22 alpha, 26-trihydroxyfurost-5-ene-3-O-beta-chacotrioside-26-O- beta-D-glucopyranoside and its corresponding 22 alpha-O methoxy analogue were also isolated for the first time from this source. The structures have been identified with the help of FAB-MS, 1H NMR, 13C NMR and extensive 2D NMR spectroscopy, as well as comparison with reported spectroscopic data.
A new monoterpene-glycoside (2-exo-beta-D-glucopyranosyl-1,8-cineol) named bucharioside from the methanol-soluble part and a new sesquiterpenoid (4,10-epoxy-6alpha-hydroxyguaiane) named buchariol from the hexane-soluble part of Salvia bucharica were obtained. Their structures were elucidated with the help of NMR spectroscopy including 1D and 2D experiments.
Thirty different fatty acids of various classes were extracted from the non-polar fraction of the seeds of Caesalpinia bonduc (L.) Roxb. (Caesal-piniaceae). Eight among them were found to be saturated while 22 were unsaturated acids, which included nine monoenoic, five dienoic, seven trienoic and one polyenoic acid. Unsaturated fatty acids were present in a large proportion (65.76%) than the saturated ones (34.24%). Spectroscopic methods (GLC and GC-MS) were used for their characterization and identification. Hexadecadienoic acid occurred in the highest proportion (21.17%). The single polyenoic acid (tetracosapentaenoate) was rare and present in traces (0.95%).
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Six compounds (two sterols, three sterol derivatives and one disaccharide) together with eight fatty acids (three saturated and five unsaturated) have been isolated from the seeds of Pongamia pinnata. Their structures were elucidated with the help of physico-chemical methods and spectroscopic techniques. The metabolities, beta-sitosteryl acetate and galactoside, stigma sterol, its galactoside and sucrose are being reported for the first time from this plant. The saturated and unsaturated fatty acids (two monoenoic, one dienoic and two trienoic) were present in exactly the same amount. Oleic acid occurred in highest amount (44.24%), stearic (29.64%) and palmitic (18.58%) acids were the next in quantity. Hiragonic and octadecatrienoic acids were present in trace amounts (0.88%).
A new bidesmosidic triterpenoidal saponin 3-O-[beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->4)-alpha-L - arabinopyranosyl]-hederagenin-28-O-[alpha-L-rhamnopyranosyl- (1-->4)-beta-D- glucopyranosyl-(1-->6)-beta-D-glucopyranosyl] ester, was isolated from the roots of Symphytum officinale. The structure was assigned by chemical methods and spectral analysis (1H, 13C, DEPT, NMR, EI-MS and FAB-MS) including 1H-1H COSY, 1H-13C COSY and HOHAHA. The prosapogenin of this saponin is also a new compound.