Abstract

• Strobilanthes tonkinensis Lindau (lat-phat-hmwe) is a medicinal and aromatic plant native to Yunan Province, China. The specimen was collected from Sin Phyu Inn Village, Pyin Oo Lwin Township, Mandalay Region. In the present study, microscopical evaluation on the aqueous, 95% and 70% ethanolic extraction, acute oral toxicity test and antioxidant activity of leaves of Strobilanthes tonkinensis Lindau were investigated. In microscopical evaluation, the presence of glandular and non-glandular trichomes, cystoliths and diacytic stomata showed the distinct characters. The leaves were extracted with 70% and 95% ethanol and water using a reflux extraction method at Research Division, University of Traditional Medicine, Mandalay in 2023. In acute oral toxicity study, six female mice (25 ± 5g) were used for each extract by using main test of Organization for Economic Co-operation and Development (OECD) 425 guidelines (2008) at Department of Medical Research, Pyin Oo Lwin Branch. In this study, there are no toxic signs and mortality in mice at the various doses of extract (175 mg/kg, 550 mg/kg, 1750 mg/kg and 5000 mg/kg) up to 14 days observation period. Therefore, the LD50 values of Strobilanthes tonkinensis Lindau was found to be more than 5000 mg/kg. Evaluation of antioxidant activity of Strobilanthes tonkinensis Lindau were measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity assays method at Department of Chemistry, University of Research Centre, Mandalay. In the antioxidant activity, the IC50 value of standard ascorbic acid is 4.271 µg/mL and the aqueous extracts, 70% and 95% ethanolic extracts are 63.618 µg/mL, 5.026 µg/mL and 2.925 µg/mL respectively. Thus, 95% ethanolic extract was the most effective antioxidant activity than the other extracts. Therefore, the leaves of Strobilanthes tonkinensis Lindau are non-toxic and a good source of phytoconstituents including with potential antioxidant and used safely in medicinal purposes.