Comparative analysis of phytochemical constituents and antioxidant activities in leaf extracts of Andrographis alata (Vahl) Nees and Andrographis echiodes (L.) Nees

Medicinal herbs function as significant sources of biologically active compounds with diverse therapeutic applications. Traditional medical practices have long relied on Andrographis alata and Andrographis echiodes of the Acanthaceae family for treating various health conditions, including diabetes, microbial infections, inflammation, liver and heart ailments, venom exposure, and cancer. The present study focuses on the comparative analysis of phytochemical constituents and antioxidant activities across petroleum ether (PE), chloroform (C), acetone (ACE), and methanol (MeOH) extracts. Quantitative evaluation indicated that A. alata possessed the highest phenol content in C extract (6.574 ± 0.006 mg GAE/g), whereas A. echiodes exhibited its maximum phenol content in PE extract (4.527 ± 0.036 mg GAE/g). The maximum flavonoid concentration was detected in the C extract of A. alata (5.433 ± 0.015 mg QE/g), while A. echiodes showed the highest level in the PE extract (3.773 ± 0.019 mg QE/g). The free radical neutralising capacity of A. alata extracts was determined via the DPPH assay, wherein the C extract exhibited the highest antioxidant efficiency among the tested solvents (IC₅₀: 126.940 ± 2.87 μg/mL), while for A. echiodes, the PE extract showed the highest activity (IC₅₀: 91.840 ± 2.15 μg/mL). These results indicate that A. echiodes exhibited slightly higher antioxidant potential compared to A. alata. The reducing capacity analysis revealed a concentration-dependent enhancement in absorbance, indicating the electron-donating potential of the extract. Ascorbic acid exhibited strong linearity (R² = 0.9984). Among A. alata, MeOH had the highest reducing power (1.112 at 500 μg/mL), while C had the lowest (0.886). In A. echiodes, C showed the highest (1.348), and ACE the lowest (1.184). The high regression values (R² > 0.99) indicate strong antioxidant potential. These findings highlight the therapeutic potential of A. alata and A. echiodes as natural antioxidants. Their strong free radical scavenging activity supports their traditional medicinal uses and underscores the importance of conserving ethnomedicinal plants for drug development in disease prevention and management.