DOI: https://doi.org/10.55373/mjchem.v25i4.199

Keywords: Clinacanthus nutans; flavonoids; tannins; antibacterial property

Abstract

Clinacanthus nutans (C. nutans) is classified under the Acanthaceae plant family found in Southeast Asia, and has been used as ethnomedicine to treat bacterial infections. In the literature to date, there is a lack of information on the phytochemical constituents in C. nutans leaf extracts and their pharmacological actions, especially their antibacterial properties. In this study, we performed a phytochemical analysis on the methanol, hexane and water extracts of C. nutans. Different chemical tests were used to screen for the presence of alkaloids, flavonoids, saponins, terpenoids and tannins in the extracts. The preliminary phytochemical screening showed that terpenoids were found in all extracts, while flavonoids and tannins were only found in the water extract, and saponins were only found in the methanol extract. Thin layer chromatography (TLC) analyses confirmed that alkaloids were absent, but various flavonoids were present in all the extracts. In addition, all the extracts were able to inhibit the growth of S. aureus and B. subtilis, with zone of inhibition diameters of ~7-10 mm. However, no inhibition was observed for all extracts against E. coli. The MIC values for the water and methanol extracts against S. aureus were similar (12.50 mg/mL). Interestingly, the water extract was twice as effective (25.00 mg/mL) as the methanol extract (50.00 mg/mL) in inhibiting B. subtilis. The minimum inhibitory concentration (MIC) values for the hexane extract could not be determined as the extract precipitated after the addition of broth, which resulted in the formation of a cloudy solution. The antibacterial activity exhibited by all C. nutans extracts against S. aureus and B. subtilis suggests their antibacterial potential towards Gram-positive bacteria.