Biomedical subjects

Fatima Khan

Publications and source records attributed to Fatima Khan.

5 recordsLinked to original sources

PubMed2006

Vasodilatory and hypoglycaemic effects of two pyrano-isoflavone extractives from Eriosema kraussianum N. E. Br. [Fabaceae] rootstock in experimental rat models.

Zulu traditional health practitioners have claimed that the roots of Eriosema kraussianum N. E. Br. (Fabaceae) and other Eriosema species (Zulu indigenous umbrella name of "uBangalala") are effective remedies for the treatment of erectile dysfunction (ED) and/or impotence. In order to scientifically appraise the significance and contribution of Eriosema kraussianum to its ethnomedical use as "uBangalala" and "VIAGRA substitute", the present study was undertaken to investigate the vasodilatory and hypoglycaemic properties of the two main bioactive chemical compounds obtained from E. kraussianum, in experimental rat models, using sildenafil citrate (VIAGRA) as the reference drug for comparison. The two E. kraussianum rootstock constituents (K1 and K2, 20-80 mg/kg p.o.) caused dose-dependent and significant (P<0.05-0.001) hypoglycaemia in rats. Relatively low to high concentrations of the plant's extracts (K1 and K2, 100-2000 microg/ml) always produced biphasic effects on rat isolated portal veins. K1- and K2-provoked responses of the isolated portal veins always consisted of concentration-related initial transient, but significant (P<0.05), contractions of the venous muscle preparations, followed by secondary, longer-lasting, highly significant (P<0.01-0.001) relaxations of the venous muscle strips. Sildenafil citrate (VIAGRA, 5-100 microg/ml) always produced concentration-related and highly significant relaxations of the rat isolated portal veins. Unlike K1 and K2 (20-80 mg/kg p.o.), however, sildenafil citrate (VIAGRA, 100 mg/kg p. o.) only caused slight and insignificant (P>0.05) reductions in the blood glucose levels of the experimental animals used. On the other hand, glibenclamide (10 mg/kg p.o.) induced highly significant (P<0.05-0.001), marked reductions in the blood glucose concentrations of the rats. The findings of this laboratory animal study indicate that the two hydro-ethanol extractives of E. kraussianum (K1 and K2) possess hypoglycaemic and secondary, vasorelaxant effects in the experimental paradigms used.

Animals↗

PubMed2005

Simple 1,4-benzoquinones with antibacterial activity from stems and leaves of Gunnera perpensa.

From the dichloromethane extract of the leaves and stems of Gunnera perpensa two new, simple 1,4-benzoquinones and a known benzopyran-6-ol were isolated. From the methanol extract phytol was obtained. The two benzoquinones, 2-methyl-6-(-3-methyl-2-butenyl)benzo-1,4-quinone (1) and 3-hydroxy-2-methyl-5-(3-methyl-2-butenyl)benzo-1,4-quinone (2) and the benzopyran, 6-hydroxy-8-methyl-2,2-dimethyl-2H-benzopyran (3) were examined for antimicrobial properties together with the crude stem, leaf and root extracts. Minimum inhibitory concentration (MIC) assays were used to quantify antimicrobial activity and the MIC values for the crude extracts of stems, roots and leaves ranged between 100 microg and >16 mg/ml against the eight microorganisms investigated. Compound 1 showed significant antimicrobial activity with the most sensitive organism being Staphylococcus epidermidis with an MIC of 9.8 microg/ml. For compound 2, no activity was noted. Compound 3 exhibited good activity against the yeasts Cryptococcus neoformans (75 microg/ml) and Candida albicans (37.5 microg/ml).

Anti-Bacterial Agents↗

PubMed2004

Venusol from Gunnera perpensa: structural and activity studies.

From the aqueous extract of the dry rhizomes of Gunnera perpensa the minor components pyrogallol, succinic acid, lactic acid, and the trimethyl ether of ellagic acid glucoside were isolated. The major constituent was identified as Z-venusol, a phenylpropanoid glucoside. Its structure was verified by X-ray diffraction. Tests on isolated uterine smooth muscle from rats showed that the whole extract stimulated a direct contractile response and induced a state of continuous contractility of the uterus once all additives had been removed from the organ bath. By contrast, venusol did not trigger the direct contractile response but induced the state of continuous contractility once the organ bath was flushed.

Animals↗

PubMed2004

Minor pyrano-isoflavones from Eriosema kraussianum: activity-, structure-, and chemical reaction studies.

The isolation and identification of two minor pyrano-isoflavones from Eriosema kraussianum is described. New studies on the original pyrano-isoflavones shows that: (i) kraussianone 2 (a major compound in the plant) can be cyclised under acid conditions, (ii) kraussianones 3 and 5 cause contraction (not relaxation as anticipated) of corpus cavernosum tissue and (iii) the structures proposed previously for 4 and 5 are confirmed by the data obtained from an X-ray study of 5.

Crystallography, X-Ray↗

PubMed2003

Recent findings on natural products with erectile-dysfunction activity.

Viagra has had a profound influence on the search for natural products with erectile-dysfunction activity. To date the "natural" equivalent is not in existence but several pure compounds from nature, e.g., Yohimbine, Citrulline, two pyrano-isoflavones, berberine, forskolin and others, have either been re-examined or are new potential candidates. Intense activity exists in the area of testing semi-purified plant extracts for erectile dysfunction activity.

Animals↗