Abstract

Tarchonanthus camphoratus (camphor bush) has been widely used for numerous medicinal purposes. The aim of the present study was to evaluate the antioxidant properties, cytotoxicity and monoamine oxidase inhibition activities of the crude dichloromethane leaf extract of T. camphoratus. The antioxidant activities were assessed using the thiobarbituric acid-reactive substances (TBARS) assay and the nitroblue tetrazolium (NBT) assay. The cytotoxicity assays were performed according to the microculture MTT method. From the MTT assay, it was determined that at a concentration of 10 mg/ml of crude extract, 95% of the neuroblastoma cells were killed. Almost 99% of the cells were viable at a concentration of 0.08 mg/ml extract. The extract also showed the ability to inhibit monoamine oxidase (MAO-A and MAO-B) with the corresponding inhibitory concentration, IC₅₀ values of 1.371 and 0.2737 mg/ml, respectively. The antioxidant activity and cytotoxic effect of the extracts increased with increase in concentration. This study suggests that the dichloromethane leave extract of T. camphoratus can potentially be used as a readily accessible source of natural antioxidants.

Key words: Antioxidant, cytotoxicity, monoamine oxidase (MAO), Tarchonanthus camphoratus, inhibitor, medicinal plant.

Abbreviation

NBT, Nitroblue tetrazolium; TBARS, thiobarbituric acid-reactive substances; MAO, monoamine oxidase; DMEM, Dulbecco’s Modified Eagle’s Medium; FBS, foetal bovine serum; ROS, reactive oxygen species; HVA,homovanillic acid; DOPAC, 3,4-dihydroxy-phenyl-acetic acid; MDA, Malondialdehyde;BHT, buthylated hydroxyl toluene; TCA, trichloro acetic acid; TBA, thiobabutiric acid;NBD, nitroblue diformazan; GAA, glacial acetic acid; PCK, potassium cyanide; PBS,phosphate buffer saline; BSA, bovine serum albumin.