A. K. Bashir

Some pharmacologic and toxicologic studies on Rhazya stricta Decne in rats, mice and rabbits

1. This work examines some in vivo and in vitro pharmacologic and toxicologic effects of extracts of Rhazya stricta, a medicinal plant in the United Arab Emirates. 2. R. stricta extracts at doses of 0.1-10 mg reduced the mean arterial blood pressure (MBP) of anesthetized rats in a dose-dependent manner. The depressor effect was partially sensitive to atropine (5 microM). Although the MBP was reduced by 50% by both doses of extracts, the normal electrocardiogram pattern and the heart rate remained unaltered. 3. Acute treatment of rats with the lyophilized extract at doses of 4 g/kg produced a significant rise in insulin concentration. In streptozotocin-diabetic rats loaded orally with glucose (1 g/kg), R. stricta at doses of 8 g/kg produced significant decreases in plasma glucose concentration at 0.5 and 1 h after treatment. 4. Chronic treatment of rats and mice for 28 days with the lyophilized extract of R. stricta did not affect the plasma glucose or insulin concentration or any of the hematological or biochemical indices measured. 5. The extracts of R. stricta (0.5-4 g/kg) dose-dependently decreased the gastrointestinal transit time in mice by 4-50%. 6. The butanolic extract of R. stricta (1 and 2 g/kg) significantly reduced the carrageenan-induced increase in raw paw edema 3 and 4 h after the extract administration. 7. The rectal temperatures of normothermic and pyrexic rats were reduced significantly 0.5 and 1 h after administration of butanolic R. stricta at doses of 1 and 2 g/kg. 8. The butanolic extract of R. stricta at doses of 1 and 2 g/kg significantly increased the reaction time on the hot plate 30 and 60 min after administration to rats. 9. At concentration < 0.05 mg/ml (bath concentration), lyophilized water and butanol extracts of R. stricta potentiated the twitch responses induced by indirect electrical stimulation in the rat phrenic nerve diaphragm preparation. The responses were inhibited by concentrations > 0.05 mg/ml. Neostigmine (2 x 10(-4)M) did not alter these effects of the extracts. 10. R. stricta extracts dose-dependently decreased the force of contraction and heart rate of the isolated rabbit heart. Atropine (1 x 10(-5)M) had no effect on the inhibitory activity of these extracts. The lyophilized water extract (> 10 mg) and butanol extract (> 5 mg) produced irreversible inhibition and disturbances in the force of contraction and heart rate.

The effect of Rhazya stricta on glucose homeostasis in normal and streptozoticin diabetic rats

The effect of R. stricta water extract on glucose homeostasis was studied in normal and streptozotocin diabetic rats. R. stricta had no effect on fasting glucose levels in normal and diabetic rats up to 7 h after its oral administration. In normal and diabetic rats R. stricta did not produce any significant effect on an oral glucose tolerance test (OGTT). Chronic administration of R. stricta in drinking water for 37 days did not produce any effect on the parameters of glucose homeostasis studied (plasma glucose, body weight, feed and fluid intake and plasma fructosamine) in the normal or diabetic phase of the experiment. The LD50 of R. stricta in mice was 2.36 g/kg body weight of the lyophilised extract and a daily administration of R. stricta to rats for 5 days did not produce any signs of organ damage.

Evaluation of the relaxant activity of some United Arab Emirates plants on intestinal smooth muscle.

Although medicinal plants are used as antispasmodic agents in folk medicine there have been no scientific studies of the phytochemical composition and usefulness of these plants for such treatment. Extracts of 23 plants used in the traditional medicine of the United Arab Emirates were tested for their effects on intestinal smooth muscle activity.

The Effect of Rhazya stricta Decne, a Traditional Medicinal Plant, on the Forced Swimming Test in Rats

Immobility induced by forced swimming is well known as an animal model of depression. Using this paradigm, we have, in the present work, tested the possibility that the medicinal plant Rhazya stricta, which has previously been found to affect the monoamine oxidase inhibitory activity in rat brain, may have an antidepressant-like action. Rats were pretreated with various doses (0.025-6.4 g/kg) of the lyophilized extract of the plant leaves, or with desipramine (10, 20, and 40 mg/kg) and were subjected to the forced swimming test. The results indicated that the plant extract produced a biphasic (bell-shaped) effect on the immobility time. The lower doses (0.1, 0.2, and 0.4 g/kg) elicited a highly significant and inversely dose-dependent decrease in immobility time, and the higher doses (0.8, 1.6, and 6.4 g/kg) showed a dose-dependent decrease in immobility time. Under the same experimental conditions desipramine (20 and 40 mg/kg) produced dose-dependent significant decreases in immobility time. Following administration of R. stricta (6.4 g/kg) the immobility time recovered progressively with time, and 4 h after its administration the immobility time was about 70% of the control level (statistically insignificant). It is concluded that R. stricta extract [or component(s) thereof] may possess an antidepressant-like effect.

Some effects of Salvia aegyptiaca L. on the central nervous system in mice

Salvia aegyptiaca L. is used for treating various unrelated conditions that include nervous disorders, dizziness, trembling, diarrhoea and piles. This work examines some effects of the crude acetone and methanol extracts of the plant given at single oral doses of 0.25, 0.5, 1 or 2 g/kg, on the central nervous system (CNS) in mice. The extracts were also tested for anti-inflammatory and antipyretic actions. Several models of nociception have been used to examine the analgesic effect of the extract. In treated mice, the extracts caused dose-related inhibition of acetic acid-induced abdominal constriction, and significantly reduced formalin-induced pain. Treatment with the extracts at doses of 0.5 and 1 g/kg significantly increased the reaction time in the hot-plate test. In treated mice both extracts caused significant and dose-related impairment of the sensorimotor control and motor activity. Treatment with both extracts did not significantly affect the rectal temperature of normothermic mice. The methanol extract (0.5 and 1.0 g/kg) did not affect the rectal temperature of hyperthermic mice, but the acetone extract was effective in significantly reducing the rectal temperature of hyperthermic mice, 0.5 and 1 h after administration of the extract at doses of 0.25-2 g/kg. It is concluded that the crude methanol and acetone extracts of S. aegyptiaca have CNS depressant properties, manifested as antinociception and sedation. Both extracts have some anti-inflammatory and antipyretic actions. On the whole, the acetone extract appeared to be slightly more effective than the methanol extract in this regard.

Effect of Extract of Rhazya stricta , a Traditional Medicinal Plant, on Rat Brain Tribulin

Rhazya stricta leaves, which have both antidepressant and sedative properties in animal models, are widely used in folk medicine in the Arabian peninsula. In this study, the effects of oral administration of leaf extracts on rat brain tribulin levels [endogenous monoamine oxidase (MAO) A and B inhibitory activity], were determined. In an acute study, low doses brought about an increase in MAO A inhibitory activity, while intermediate doses caused a significant reduction. The highest doses had no significant effects on activity. There were no significant effects on MAO B inhibitory activity at any dose. Subchronic administration (21 days) caused a significant decrease in MAO A inhibitory activity, most prominent at low dosage, and an increase in MAO B inhibitory activity. Acute intramuscular administration also resulted in a similar pattern. Such paradoxical effects were at least partially explained when different extracts of the leaves were used; a weakly basic chloroform fraction caused an increase in MAO A inhibitory activity, whereas butanol extracts brought about a decrease. These fractions had no significant effects on MAO B inhibitory activity. The findings show that Rhazya stricta leaves contain at least two different components that affect MAO inhibitory activity in opposite directions. It may be that the antidepressant and sedative actions of the plant are explicable in terms of these different components.

Antiinflammatory Activity of Some Medicinal Plants of the United Arab Emirates

AbstractThe antiinflammatory activity of 22 plants used in folk medicine, or indigenous in the United Arab Emirates, was tested using the carrageenan-induced rat paw edema method. Three plants (Citrullus colocynthis, Hammada elegans and Rhazya stricta) showed such activity. Activity-guided fractionation of Hammada elegans extract led to the isolation of a single active compound which was identified as piperidine hydrochloride. Citrullus colocynthis-m^aced antiinflammatory activity may by due to loss of body water.

Flavonoids of Limonium axillare

AbstractUsing chromatographic techniques, kampferol, luteolin, myricetin, apigenin, luteolin-7-O-glucoside and apiin were isolated from a methanol extract of Limonium axillare and antimicrobial activity was investigated. This is the first report of apiin in the Plumbaginaceae. In addition to these flavonoids, sitosterol, stigmasterol, and sitosterol glucoside were identified.

Antioxidant action of extract of the traditional medicinal plant Rhazya stricta Decne. in rats

The effects of a leaf extract of the traditional medicinal plant Rhazya stricta (0.25, 1.0 and 4.0 g/kg/day for 3 days) on reduced glutathione (GSH), lipid peroxidation (LP) and ascorbic acid (AA) concentrations in the liver and kidneys were studied in rats 24 h after the last dose. The plant extract, at a dose of 0.25 g/kg, did not significantly affect the concentrations of GSH, LP or AA in the liver or kidneys. At a dose of 1.0 g/kg, the plant extract significantly increased the GSH concentration in the liver, but did not affect the GSH concentration in the kidneys, or LP or AA in the liver or kidneys. The plant extract (4.0 g/kg) significantly increased the GSH and decreased LP peroxidation, but did not affect the AA concentrations in the liver and kidneys.

Central nervous system activity of Leucas inflata Benth. in mice

The analgesic activity of the methanol and acetone extracts of Leucas inflata L. (family Labiatae) was evaluated in mice using different experimental models. The effect of the two extracts on pentobarbitone-sleeping time, motor activity, sensorimotor coordination, carrageen induced inflammation, and brewers yeast-induced pyrexia has also been investigated. The two crude extracts have been phytochemically analyzed and some constituents isolated and characterized. These included stigmasterols, a chromone and coumarins. Extracts of L. inflata L., given at single oral doses of 0.25, 0.5, 1.0 or 2.0 g/kg, significantly and dose-dependently, reduced formalin-induced pain, acetic acid induced abdominal constrictions and increased the reaction time in the hot-plate test. Both extracts caused significant and dose-related impairment in the sensorimotor control and ambulatory and total motor activity of treated mice. Both extracts exhibited anti-inflammatory action by reducing paw edema of treated mice. The extracts did not significantly affect the rectal temperature of normothermic mice. However, they were effective in preventing Brewers yeast induced pyrexia. It is concluded that the crude methanol and acetone extract of L. inflata has CNS depressant properties, manifested as antinociception and sedation. Both extracts have anti-inflammatory and antipyretic actions.