Determination of antioxidant property of commercially selling Borneo plants by 2,2'-azino-di-(3-ethylbenzthiazoline-6-sulfonic acid) free radical scavenging assay.

Background: Antioxidants from natural products are important to counter the effect of reactive oxygen species occur in chronic diseases and metabolic disorders. Objective: This study evaluated the antioxidant activities of the leaf extracts from three plants found in Brunei: Melastoma malabathricum (MM), Scurrula ferruginea (SF), and Clinacanthus nutans (CN). Methods: The plant leaves were collected from in Brunei Darussalam air-dried and pulverized into powder. The extracts obtained from Soxhlet, fractionation, and maceration were freeze-dried and the total antioxidant status was evaluated using 2,2'-azino-di-(3-ethylbenzthiazoline-6-sulfonic acid) scavenging radical activities in vitro assay. Both MM and SF extracts exhibited promising antioxidant capabilities. Results: The recorded antioxidant activities of MM with 5 mg/mL of methanolic, ethyl acetate, ethanolic, and aqueous extracts were 2.10, 2.12, 2.16, and 3.25 mmol/L, respectively. The antioxidant activities of the same concentration of SF aqueous, ethyl acetate, and methanolic extracts were 2.23, 2.35, and 2.46 mmol/L, respectively. Conversely, CN extracts used in the study did not show significant antioxidant activity. Conclusion: The present study demonstrated that MM and SF extracts possess excellent antioxidant activities. The results suggest that these plants have therapeutic potential for metabolic syndrome and inflammatory diseases. Thus, further investigations for anti-inflammatory and analgesic activities are recommended. [ABSTRACT FROM AUTHOR]