Studies on the Alkaloids of Rhazya stricta

A new strychnos-type alkaloid, bharhingine ( 1), has been isolated from the leaves of RHAZYA STRICTA. Its structure has been assigned on the basis of spectral studies including 2D-NMR measurements. The structure and stereochemistry of another Aspidosperma-type alkaloid, strictanol ( 2) has been investigated by extensive NMR studies including hetero-COSY experiments and NOE difference measurements. Isolation of another strychnos-type alkaloid, vincanicine ( 3), not previously reported from this plant, is also described.     

Alkaloids formed by somatic hybrids ofRauwolfia serpentina + Rhazya stricta

Translated from Khimiko-farmatsevticheskii Zhurnal, Vol. 28, No. 10, pp. 61–63, October, 1994.     

Mechanism of the hypotensive action of Rhazya stricta leaf extract in rats.

The hypotensive action of Rhazya stricta lyophilized leaf extract was found to be partly caused by the electrolyte content of the extract, and partly caused by a strongly basic alkaloidal fraction (AF). AF (0.05-1.6 mg animal(-1)) caused a dose-dependent reduction in mean arterial blood pressure (MAP) of urethane-anaesthetized rat preparations. In naiuml;ve pithed rats, AF administration (0.5-2.0 mg animal(-1)) significantly increased MAP. In pithed or spinalized rats made normotensive by noradrenaline infusion, AF (0.25 mg animal(-1)) did not cause any significant changes. Direct intracerebroventricular injection of AF (0.1-0.4 mg) markedly and significantly reduced MAP. It is suggested that the hypotensive action of AF to be mediated by a central mechanism.     

The Isolation and 13C-NMR of Dihydrocorynantheol and Rhazimol (Deacetylakuammiline), Alkaloids from the Roots of Rhazya stricta.

The isolation and (13)C-NMR spectra of dihydrocorynantheol and rhazimol from the roots of RHAZYA STRICTA are reported.     

Effect of Rhazya stricta Decne on monoamine oxidase and cholinesterase activity and brain biogenic amine levels in rats

The effect of treatment with the medicinal plant Rhayva stricta Decne, on monoamine oxidase (MAO) and cholinesterase activity, and on the concentration of brain biogenic amines was studied in rats. R. stricta extract, at doses of 0.2 and 0.5 g kg(-1), significantly (P < 0.05-0.01) increased the hepatic and cerebral activity of MAO by 36-127%. The higher doses used (2.0 and 8.0 g kg(-1)) produced smaller (10-26%) and statistically insignificant increases in MAO activity in liver and brain. Cholinesterase activity in blood, liver and brain was not significantly influenced by treatment with R. stricta. The concentrations of the measured biogenic amines (noradrenaline, adrenaline, 5-hydroxytryptamine and dopamine) were significantly lowered in rats treated with R. stricta. The observed increase in MAO activity may be responsible for the lowered biogenic amines levels and may, in part, be responsible for the pharmacological effects of R. stricta extract in rats.     

Divergence of the indole alkaloid pattern in two somatic hybrid plant cell subcultures of Rauvolfia serpentina x Rhazya stricta

The alkaloid pattern in Rauvolfia serpentina x Rhazya stricta somatic hybrid cell subcultures R x R17 K was studied and 11 compounds were identified on the basis of their spectral data. Among them, 1,2-dehydroaspidospermidine, rhazinilam, stemmadenine and tabersonine were reported as typical of Rhazya species while vomilenine and sarpagine are characteristic of Rauvolfia alkaloid metabolism. The alkaloid pattern in R x R17 K subcultures was compared with that in the other hybrid cell subcultures (R x R17 M) which were developed from the same origin hybrid cultures but have been maintained separately for about ten years. The data presented here exhibit pronounced divergence of the alkaloid patterns in R x R17 K and R x R17 M cell subcultures.     

The effect of Rhazya stricta Decne, a traditional medicinal plant, on spontaneous and drug-induced alterations in activity of rats.

The effect of acute and chronic treatment of rats with a lyophilized extract of the leaves of the medicinal plant Rhazya stricta on total and ambulatory activity was studied. Given acutely at single oral doses of 1, 2, 4, and 8 g/kg, the extract produced dose-dependent decreases in total activity and ambulatory activity. Diazepam (20 mg/kg, orally) produced a decrease in rat activity comparable to that produced by a dose of 1 g/kg of the extract. When given daily at an oral dose of 2 g/kg for 21 consecutive days, the extract produced, on the last day of treatment, significant decrease in activity amounting to about 30% of control activity levels. Subcutaneous (SC) treatment of rats with caffeine (7.5, 15, and 30 mg/kg), dose-dependently and significantly increased total activity and ambulatory activity. These effects were dose-dependently attenuated when the extract was given concomitantly with caffeine at oral doses of 1, 2, and 4 mg/kg. Treatment of rats with zoxazolamine alone (10, 20, or 40 mg/kg, SC) or R. Stricta (1 and 4 g/kg orally) alone significantly decreased total and ambulatory activities. Concomitant treatment with zoxazolamine and R. Stricta decreased the rats activity to a greater degree than with either treatment given alone.     

The Effect on Plasma Glucose,Insulin and Glucagon Levels of Treatment of Diabetic Rats with the Medicinal Plant Rhazya stricta and with Glibenclamide,Alone and in Combination

Because many diabetic patients in the United Arab Emirates use medicinal plants as a supplement to treatment with insulin or oral hypoglycaemic agents, the effect on plasma glucose, insulin and glucagon concentrations of simultaneous treatment of streptozotocin-diabetic rats with Rhazya stricta extract and glibenclamide has been examined. Treatment of control rats with the extract at oral doses of 0.5, 20 and 4.0 g kg^? did not significantly affect the concentration of glucose, insulin or glucagon for up to 4 h after administration of the extract. The same doses in diabetic rats reduced the glucose level 1 h (2 and 4 gkg^?) and 2h (4 gkg^?) after administration of the extract. This was accompanied by significant increases in insulin concentration 1, 2 and 4 h after administration of the extract at doses of 2 and 4 gkg^?. Glibenclamide (2.5, 5.0 and 10.0 mgkg^?) dose-dependently reduced glucose and glucagon levels, and increased that of insulin in normal and diabetic rats. Simultaneous treatment of normal and diabetic rats with the plant extract (0.5, 20 and 5.0 gkg^?) and glibenclamide (5.0 mg kg^?) significantly exacerbated the effects on glucose, insulin and glucagon induced by the extract or by glibenclamide when given separately. When the plant extract was given at doses of 0.5, 2 and 4 g kg^? per day for 6 consecutive days the glucose level was reduced by approximately 6, 8 and 30%, respectively. No significant effect was seen on the levels of cholesterol or protein. These results imply that co-administration of the extract with glibenclamide might adversely interfere with glycaemic control in diabetic patients.     

Alkaloids of Androcymbium melanthioides var. stricta1

The aerial parts of ANDROCYMBIUM MELANTHIOIDES yielded known alkaloids cornigerine, colchicine, N-formyl- N-deacetylcolchicine, 2-demethylcolchicine, 3-demethylcolchicine, demecolcine, 2-demethyldemecolcine, 3-demethyldemecolcine, beta-lumicornigerine, beta-lumicolchicine, gamma-lumicolchicine, androcymbine, O-methylandrocymbine, and melanthioidine. Of these, O-methylandrocymbine and beta-lumicornigerine are reported for the first, time. The alkaloid, formerly designated as compound AM-3, has been identified as N-deacetyl- N-dimethyl-gamma-lumicornigerine 1. Its spectral data are given.