Khalid Aftab

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.

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.

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.

Presence of acetylcholine-like substance(s) inSesamum indicum

Alcoholic extract of seeds ofSesamum indicum (SI, 1–30 mg/kg) caused hypotensive action in anesthetized rats. Heart rate was also decreased at slightly higher doses (10–30 mg/kg). Pretreatment with atropine (2 mg/kg) abolished these cardiovascular responses. In isolated spontaneously beating atria from guinea-pigs, SI caused decrease in force and rate of atrial contractions. In isolated guinea-pig ileum and rat uterus, SI (100–1000 ug/ml) produced contractile responses. All these actions of SI were abolished in the presence of atropine (1 μM). These results indicate that alcoholic extract of seeds ofSesamum indicum contains acetylcholine-like constituents(s) which explains some of the folkloric uses of plant.

Symphytoxide A, a triterpenoid saponin from the roots of Symphytum officinale

A new triterpenoidal saponin of hederagenin named symphytoxide A has been isolated from the ethanolic extract of the roots of Symphytum officinale and characterized on the basis of chemical investigations and spectroscopic studies as 3-O-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->4)- alpha-L-arabinopyranosyl] hederagenin. The structure of this new saponin was established on the basis of 1D and 2D NMR experiments including heteroCOSY, COSY-45 degrees as well as HMBC measurements and other spectroscopic techniques. The saponin exhibited hypotensive activity in anesthetized rats.

Cholinergic Action of Crude Saponins from Castanospermum australe

AbstractThe effect of crude saponins of Castanospermum australe (CA) was studied in anesthetized rats and on isolated tissue preparations. The results showed that CA in the dose range of 1-30 mg/kg produced a fall in blood pressure and heart rate in normotensive anesthetized rats. Pretreatment of animals with atropine (2 mg/kg) abolished both hypotensive and bradycardiac effects of CA. In isolated guinea-pig atria, CA produced negative inotropic and chronotropic responses at 100-1000 μg/mL. When tested on isolated guinea-pig ileum, it produced contractile responses similar to those of acetylcholine (ACh). All these responses of CA and ACh on cardiac and smooth muscle preparations were completely blocked by atropine (0.1 μg/ml). These data indicate that the crude saponins from Castanospermum australe mediate all their effects through a mechanism similar to that of acetylcholine.

Pharmacological Actions of Cuscuta reflexa

AbstractAn ethanol extract of Cuscuta Reflexa (CR) caused dose-dependent decreases in arterial blood pres sure and heart rate in pentothal anesthetized rats. These effects were not blocked by atropine (1 mg/ kg) and CR did not alter the pressor response of norepinephrine. These results indicate ihat the hypotensive and bradycardiac effects of CR are independent of cholinergic receptor stimulation or adrenergic receptor blockade. In spontaneously beating guinea-pig atria, CR caused decreases in the force and rate of atrial contractions. These effects remained unaltered in the presence of atropine (0.1 pM). In guinea-pig ileum, CR inhibited both acetylcholine- and histamine-induced contractions to a similar extent. CR also abolished spontaneous contractions of rat uterus. These data indicate that CR in a non-specific depressant on all the isolated tissues tested and this action is probably responsible for its hypotensive and bradycardiac effects observed in vivo.

Phyto-pharmacology of saponins from Symphytum officinale L.

Symphytum officinale L. (comfrey) is a plant of Euro-American origin which belongs to the family Boraginaceae 1. It is a part of the practice of naturopathic medicine in Europe and America and is reported to have multiple therapeutic uses2,3,4.5,6 which include antiseptic, analgesic, antiinflammatory and antiulcer properties. It is also considered useful in several skin complications such as chronic wounds, burns, sores, eczema and wrinkles7. Moreover, the roots of this plant are used in he treatment of colds, asthma, bronchitis, tuberculosis, and hemorrhoids8. Comfrey is also. used in kidney diseases, cancer, and anaemia9.