Comparative In vitro Antioxidant Potential of Leaf, Bark, and Stem Extracts of Dalbergia latifolia Roxb.

Abstract

Dalbergia latifolia Roxb. is a high-value species known for its phytochemical richness, although the comparative bioactive potential of its different plant parts remains underexplored. The present study evaluated the in vitro antioxidant potential of ethanolic leaf (ELDL), stem (ESDL), and bark (EBDL) extracts of D. latifolia. Phytochemical screening confirmed the presence of major secondary metabolites, including phenolics, flavonoids, tannins, terpenoids, and sterols. Total phenolic and flavonoid contents showed minor, non-significant variation among extracts (P > 0.05), with ELDL showing the highest phenolic content (8.09 ± 1.12 mg GAE/g) and ESDL showing the highest flavonoid content (3.68 ± 0.01 mg QE/g). Antioxidant activity was assessed using total antioxidant capacity (TAC), reducing power assay (RPA), DPPH, and ABTS radical scavenging assays. TAC differed significantly among extracts, with EBDL showing the highest activity (323.83 ± 3.70 mg AAE/g), followed by ESDL and ELDL (P < 0.05). In contrast, RPA values were statistically comparable among extracts (p = 0.1621). In DPPH, ELDL and ESDL showed comparable IC₅₀ values (16.00 ± 0.76 and 16.18 ± 0.18 µg/mL) and significantly stronger activity than EBDL (31.26 ± 3.67 µg/mL; P < 0.0001). Similarly, in ABTS, ELDL and ESDL showed lower IC₅₀ values than EBDL (P < 0.0001), with ELDL comparable to the standard Trolox (P = 0.0563). The findings demonstrate assay-dependent antioxidant variation in D. latifolia, with bark showing stronger total antioxidant capacity and leaf and stem extracts showing superior radical scavenging activity. This study can help understand tissue-specific bioactivity and its therapeutic use to guide extraction as well as spatial isolation and characterization of the phytoconstituents.