Toxicity evaluation of a standardised 50% ethanol extract of Orthosiphon stamineus.

AIM OF THE STUDY: The present investigation was carried out to evaluate the safety of standardised 50% ethanol extract of Orthosiphon stamineus plant by determining its potential toxicity after acute and subchronic administration in rats. MATERIALS AND METHODS: For acute toxicity study, up and down method (limit dose) was adapted. A single dose of 5000 mg/kg of the standardised 50% ethanol extract of O. stamineus was given orally to 5 healthy Sprague-Dawley (SD) female adult rats. The rats were observed for mortality and clinical signs for 3 h and then periodically for 14 days. While in the subchronic toxicity study, the extract was administered orally at doses of 1250, 2500 and 5000 mg/kg per day for 28 days to female and male SD rats, respectively. The animals were sacrificed, followed by examination of their organs and blood serum. RESULTS: In the acute toxicity study, standardised 50% ethanol extract of O. stamineus at a dose of 5000 mg/kg caused neither visible signs of toxicity nor mortality. All five rats survived until the end of observation period. While in subchronic toxicity, administration of the standardised 50% ethanol extract of O. stamineus at 1250, 2500, and 5000 mg/kg for 28 days did not produce any mortality and there were no significant differences in the general condition, growth, organ weights, hematological parameters, clinical chemistry values, or gross and microscopic appearance of the organs from the treatment groups as compared to the control group. CONCLUSIONS: Standardised 50% ethanol extract of O. stamineus did not cause any death nor did it cause abnormalities in necropsy and histopathology findings. There were no acute or subchronic toxicity observed and this extract could be devoid of any toxic risk. The NOAEL for the standardised 50% ethanol extract of O. stamineus is 5000 mg/kg per day for 28 days.

Evaluation of the genotoxicity of Orthosiphon stamineus aqueous extract.

AIM OF THE STUDY: Orthosiphon stamineus, Benth, also known as Misai Kucing in Malaysia and Java tea in Indonesia, is traditionally used in Southeastern Asia to treat kidney dysfunctions, diabetes, gout and several other illnesses. Recent studies of Orthosiphon stamineus pharmacological profile have revealed antioxidant properties and other potentially useful biological activities thereby lending some scientific support to its use in folk medicine. So far the genotoxicity of Orthosiphon stamineus extracts has not been evaluated. In this study the genotoxic potential of Orthosiphon stamineus aqueous extract was investigated by the Salmonella/microsome mutation assay and the mouse bone marrow micronucleus test. MATERIALS AND METHODS: Chemical composition of Orthosiphon stamineus aqueous extract was analyzed by High Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD). The Salmonella/microsome assay (TA97a, TA98, TA100 and TA1535; plate incorporation method) was performed in the presence or in the absence of extrinsic metabolic activation (S9 mixture). In the mouse micronucleus assay, Orthosiphon stamineus extract was administered by gavage (0, 500, 2000 and 4000 mg/kg body weight/day for 3 days) to male and female Swiss Webster mice (N=6 per dose per sex) and bone marrow cells were harvested 24 h after the last dose. Ethoxy-resorufin-O-dealkylase (EROD) and benzyloxy-resorufin-O-dealkylase (BROD) activities were determined in mouse liver microsomes. RESULTS: The chemical analysis revealed that the Orthosiphon stamineus extract contained flavonoids (sinensetin, eupatorin), caffeic acid, and rosmarinic acid (44.00±1.879 µg/mg), the latter seemed to be one of its major constituent. Tested at doses up to 5000 µg/plate, the Orthosiphon stamineus extract was not toxic to Salmonella tester strains and did not increase the number of revertant colonies over the background incidence. In the mouse bone marrow assay, the extract did not alter the polychromatic:normochromatic erythrocytes (PCE:NCE) ratio, nor did it increase the incidence of micronucleated polychromatic erythrocytes (MNPEs). No overt toxicity and no change of CYP1A (EROD) and 2B9/10 (BROD) activities were noted. CONCLUSIONS: Based on the aforementioned findings, it is concluded that the use of Orthosiphon stamineus in the traditional medicine poses no genotoxic risk.

Acute toxicity of Orthosiphon stamineus Benth standardized extract in Sprague Dawley rats.

The acute toxicity of standardized extract of Orthosiphon stamineus was studied in Sprague Dawley rats. The rats were administered a single dose of 5000 mg/kg body weight (BW) orally on Day 0 and observed for 14 days. There were no deaths recorded and the animals did not show signs of toxicity during the experimental period. The effect of the extract on general behavior, BW, food and water intake, relative organ weight per 100 g BW, hematology and clinical biochemistry were measured. All the parameters measured were unaffected as compared to the control. The acute toxicity LD(50) was estimated to be > 5000 mg/kg BW.

Toxicity study of Orthosiphon stamineus Benth (Misai Kucing) on Sprague Dawley rats.

Orthosiphon stamineus Benth (Family: Lamiaceae) or locally known as Misai Kucing has been widely used in Malaysia for treating kidney problems, gout, and diabetes. This study aims to evaluate the possible toxic effect after following fourteen days oral administration of methanol extract of O. stamineus in female Sprague Dawley (SD) rats. Control groups were treated orally with distilled water (vehicle) while the four test groups were treated up to fourteen days with 0.5 g/kg, 1 g/kg, 3 g/kg and 5 g/kg body weight of methanol extract of O. stamineus respectively. Toxicity of the methanol extract of O. stamineus was evaluated by the incident of lethality, side-cage observation and blood serum biochemical parameters. No lethality or adverse toxic signs were seen during the experimental period. A significant decrease in several serum biochemical parameters i.e. AST and ALT and increase in liver weight was observed in young female SD rat after being fed fourteen days with methanol extract of O. stamineus. No delayed toxic effect and lethality was observed in all rats during fourteen days of recovery period. In conclusion, methanol extract of O. stamineus within these range and treatment duration would not cause any severe toxic effects and organ damages in rats.