Abstract:
Herbal medicines have been gaining popularity worldwide. At present Thai herbs are widely used in several Thai spas and hospitals for health and beauty benefits. Conceptually, herbs are usually considered non-toxic by the general public due to their natural origin. However, the consumption of herbs is well-known to be capable of producing adverse health effects. In this study, six commercially available herbal preparations, Ya-ayu-wattana (Thai herbal elixir), some herbal weight loss products, Black pepper herbal drug (Piper nigrum), Kha-min-chan (Curcuma longa), Wan-Chak-Mod-Luk herbal drug (Curcuma xanthorrhiza), and essential oil of Plai (Zingiber cassumunar), were randomly selected for investigation in to the acute oral toxicity test in rats and mutagenicity test in bacterial reverse mutation test system. Five herbal preparations, Ya-Ayu-wattana, herbal weight loss product, Black pepper herbal drug, Kha-min-chan herbal drug, and Wan-chak-mod-luk herbal drug were extracted with 95% ethanol and dried by lyophilizer. The essential oil of Plai was extracted by steam distillation. Acute toxicity studies shown that the essential oil of Plai had high toxic effects while other herbal preparations shown no sign of toxicity. The toxicity signs were salivation, weakness, decrease of muscle tone, involuntary urination, hypersecretion, and dypnea as well as death at the concentration of 1500 mg/kg-BW in a male rat and 750 mg/kg-BW, 1000 mg/kg-BW and 2000 mg/kg-BW in female rats. The histopathological examination of the dead animals after essential oil of Plai administration indicated mild to severe congestion, acute interstitial pneumonitis, intraalveolar hemorrhage, and pulmonary edema. In the liver, mild to moderate liver cell congestion, swelling of hepatocytes, and microvesicular fatty change had occurred. In the kidney, mild to moderate congestion and focal cloudy swelling of tubules were observed. The severity of toxicity depended on the dose. Essential oil of Plai caused reduction in body weight and food consumption, the results shown significant decrease in the body weight and food consumption when compared to the control group (p<0.05). Six herbal extracts were further study for mutagenic property by bacterium test system. And the results of Ames test exhibited no mutagenic effect of the six herbal extracts tested in the absence and presence of S9 fraction. However, Plai extracted possessed dose response to Salmonella typhymurium TA98 with S9 mix test system. The results from this study suggested that the 6 Thai herbal preparations not caused acute toxicity when given orally but the essential oil of Plai is not appropriate for use as an oral herbal medicine. The evaluation of the toxicity of these herbal preparations should be clarified.