Phytochemical profile and DPPH radical-scavenging activity of Lumnitzera racemosa leaf extracts from Bontang, Indonesia

Mismawati A, Nurfadilah, Syahrir R M, Wulandary R, Ruga R, Bulan DE. 2026. Phytochemical profile and DPPH radical-scavenging activity of Lumnitzera racemosa leaf extracts from Bontang, Indonesia. Asian J Nat Prod Biochem 24 (2): f240204. https://doi.org/10.13057/biofar/f240204. Mangrove plants are promising sources of antioxidant-related natural products; however, the phytochemical characteristics and bioactivities of many species remain insufficiently documented, particularly across specific coastal ecosystems. This study evaluated the phytochemical profile and DPPH radical-scavenging activity of Lumnitzera racemosa leaf extracts collected from the mangrove ecosystem of Bontang, East Kalimantan, Indonesia. Successive maceration was performed with hexane, ethyl acetate, and methanol, in that order, and the present study focused on the ethyl acetate and methanol extracts. The extracts were analyzed for qualitative phytochemical constituents, Total Phenolic Content (TPC), Total Flavonoid Content (TFC), Terpenoid-Reactive Content (TRC), and DPPH radical-scavenging activity. Leaves collected from several trees were pooled into one composite sample, and laboratory measurements were performed in analytical triplicate. The methanol extract showed higher TPC and TRC values, with 134.54 ± 10.70 mg GAE/g extract and 315.46 ± 2.04 mg NE/g extract, respectively, than the ethyl acetate extract, which showed 46.83 ± 9.03 mg GAE/g extract and 110.85 ± 0.77 mg NE/g extract, respectively. In contrast, TFC values were similar between the methanol and ethyl acetate extracts, with values of 42.36 ± 1.27 mg QE/g extract and 41.53 ± 1.27 mg QE/g extract, respectively. At the lowest final assay concentration of 5 µg/mL, DPPH inhibition reached 87.53 ± 0.96% for the methanol extract and 67.86 ± 2.96% for the ethyl acetate extract; at the highest final assay concentration of 50 µg/mL, the corresponding values were 95.37 ± 0.15% and 96.43 ± 0.29%. Because both extracts exceeded 50% inhibition at the lowest tested final assay concentration, their IC₅₀ values were reported as <5 µg/mL, as the 50% response was not bracketed within the tested concentration range. These findings provide a preliminary extract-level profile and support further investigation using lower concentrations, independent biological samples, complementary antioxidant assays, and compound-level characterization.