DOI: https://doi.org/10.55373/mjchem.v24i2.191

Keywords: M. speciosa; Rubiaceae; antioxidant; antimicrobial; cytotoxic assay

Abstract

The leaves of Mitragyna speciosa were traditionally used by natives as a substitute for opium. Nowadays, recreational use of M. speciosa leaves is increasing and has become a concern because of the lack of information and studies about its potential health risks. This study evaluated the antioxidant, antimicrobial, and cytotoxic activities of the crude hexane and DCM extracts of M. speciosa. Antioxidant activity was tested against DPPH, ABTS, beta carotene bleaching, FRAP, and total phenolic content (TPC) assays. Antimicrobial activity was investigated by disc diffusion and microdilution methods to determine the zone of inhibition, MIC and MBC values. The cytotoxic activity was evaluated using MTT assays. Two breast cancer cell lines (MCF7 and MDA-MD-231), two colon cancer cell lines (SW948 and HT29) and a lung cancer cell line were tested with the DCM and hexane extracts (A549). The DCM leaf extract showed the highest total phenolic content (TPC) (84.63±9.01 μg GE/mg) while the hexane extract showed the lowest total phenolic content (74.04±7.07 μg GE/mg). However, the total flavonoid (TFC) content was higher in the hexane extract (97.14±1.74 μg QE/mg) than the DCM extract (59.88±4.25 μg QE/mg). Both extracts showed DPPH free radical scavenging (EC50 >1mg/mL), ABTS (hexane extract: 20.84±0.92 mg/mL; DCM extract: 39.49±2.28 mg/mL) and beta carotene bleaching (hexane extract: 78.29 μg/mL; DCM extract: 75.17±3.26 μg/mL), FRAP (hexane extract: 11.45±0.99 μg/mL; DCM extract: 7.94±0.96 μg/mL). The cytotoxic assay for the DCM extract was moderately toxic (IC50 value ranging 2.86 to 14.81 μg /mL) on tested cancer cells, while the hexane extract showed IC50 values of more than 100 μg/mL for most of the tested cells. All extracts exhibited moderate to weak action, with MIC/MBC values ranging from 0.625 to 10 mg/mL. These findings demonstrated that the M. speciosa extracts possessed a variety of important biological properties.