FLAVONOID CONTENT, ANTIBACTERIAL AND ANTIOXIDANT ACTIVITIES OF MAT QUY (Morinda parvifolia Bartling Ex Candolle)

Abstract

Morinda parvifolia (commonly known as “Mat quy”), belonging to the genus Morinda and the family Rubiaceae, has been traditionally used in folk medicine for the treatment of infectious and gastrointestinal disorders. To date, however, there have been limited in-depth studies published on the flavonoid content and biological activities of this species. Objective: To determine the flavonoid content and to evaluate the antibacterial and antioxidant activities of flavonoid-rich fractions. Methods: Total flavonoid content was quantified using the AlCl₃ colorimetric complexation method. The antibacterial activity of flavonoid-rich extract fractions was assessed by the agar disc diffusion method and the broth microdilution method to determine the minimum inhibitory concentration (MIC). Antioxidant activity was evaluated using the DPPH free radical scavenging assay. All experiments were performed in triplicate, and the results are expressed as mean values. Results: The total flavonoid contents of the n-hexane, ethyl acetate, and n-butanol fractions were 2.834, 3.820, and 1.358 mg quercetin equivalents (QE)/g extract, respectively. The ethyl acetate fraction exhibited the highest flavonoid content and demonstrated the strongest antibacterial activity against Staphylococcus aureus (inhibition zone diameters ranging from 13.67 to 16.67 mm) and methicillin-resistant S. aureus (MRSA) (inhibition zone diameters of 12.33 - 15.67 mm). The corresponding MIC values were 15.625 mg/mL and 7.8125 mg/mL. In the DPPH assay, this fraction also showed the most potent antioxidant activity, with an IC₅₀ value of 389.083 µg/m. Conclusion: The flavonoid-rich ethyl acetate fraction of Morinda parvifolia (3.820 mg QE/g extract) exhibited the strongest antibacterial activity against S. aureus ATCC 25923 and MRSA, as well as the highest antioxidant capacity among the three investigated fractions.