*Medicinal Plant Research Institute, Department of Medical Sciences
**Division of Clinical Pathology, Department of Medical Sciences,
Tiwanond Road, Nonthaburi11000
Bulletin of Department of Medical Sciences 1999; 41(1): 41-54
Thai with English abstract
This study was conducted to obtain additional information on
the chronic toxicity of water extract of Orthosiphon aristatus (BI.) Miq. or Ya-Nuat-Maeo in Thai.
Wistar rats were divided into 4 groups of 24 rats (male 12, female 12). Control group received no treatment
while plant extract was given to 3 treatment groups by oral gavage at the doses of 0.96, 2.4 or 4.8 g/kg/day
equivalent to dry crude drug 10, 25 and 50 g/kg/day or 50, 125 and 250 folds of recommended therapeutic
dose of 10 g/day/50 kg body weight, respectively. No differences in body weight or food consumption were
found among groups of animals. Hematological examination, blood chemistry, gross and histopathological
examinations of the visceral organs were determined after the completion of 6-month study.
Platelet counts of female rats receiving the highest dose of the extract was significantly higher than that
of the Control, but was still in the normal rang. It was found that serum sodium levels of all extract treated
groups was significantly lower whereas the serum potassium level tended to be higher than that of the control.
Serum glutamic-oxalacetic transaminase and liver weight of the male rats receiving 0.96 g/kg/day was
significantly higher than those of the control. Alkaline phosphatase levels of male rats treated with the
extract were also higher than that of the control. Histopathological examinations revealed fatty change of
the liver in male rats and nephrocalcinosis in female rats; however, the incidence of such pathological
findings was not different between extract-treated groups and control groups. In contrast, the incidence of
hydrocalyx in male rats receiving highest dose of the extract was significantly higher than that of the control.
Taken together, It was found that high doses of the extract used in this study could cause a reduction of serum
sodium level in all extract-treated groups and increase alkaline phosphatase level and incidence of hydrocalyx
in male rats, hence, prolonged use of high dose O. aristatus should be avoided.