Biological activities and safety of Thanaka (Hesperethusa crenulata) stem bark

Abstract

Ethnopharmacological relevance: The stem bark powder of Hesperethusa crenulata or Thanaka has been used on the face by Myanmar women for more than a thousand years as a skin care regiment.

Aim of the study: The aim of the current study was to both verify the safety and evaluate some biological activities of the Thanaka bark.

Materials and methods: Maceration of the Thanaka bark powder resulted in hexane, dichloromethane, ethyl acetate, methanol, 85% ethanol and water extracts. For the safety evaluation, cytotoxicity and genotoxicity of each extract were tested. Antibacterial, tyrosinase inhibition, antioxidant and anti-inflammatory activities were evaluated for each extract.

Results and conclusions: Extracts from Thanaka bark showed strong anti-inflammatory, significant antioxidation, mild tyrosinase inhibition and slight antibacterial activities. All extracts and the original bark powder showed no detectable genotoxicity while very low cytotoxicity with IC(50) value of more than 12 mg/ml was detected in the water extract. Thus, the use of the Thanaka bark in the form of a watery paste as a skin care regiment is not only safe but also beneficial to skin.