Comprehensive Study on Phytochemical Constituents and Bioactive Potential of Aerial Part Extracts of Strobilanthes attenuata: An Underexplored Medicinal Plant

Strobilanthes attenuata (Acanthaceae), an underexplored plant from Uttarakhand, was evaluated for its phytochemical composition and biological potential. Four solvent extracts (SAH, SAE, SAA, and SAM) were prepared and assessed for qualitative phytochemical analysis, total phenolic content, total flavonoid content, antioxidant and antimicrobial activities. Preliminary phytochemical screening revealed diverse secondary metabolites in SAA and SAM. The highest TPC (112.2 ± 1.79 µg GAE/mg) was exhibited by SAM, while SAA showed the highest TFC (191.8 ± 2.29 µg QE/mg). Antioxidant assays revealed that SAA demonstrated 63.47% inhibition in DPPH and 90.84% inhibition in ABTS assays at 100 µg/mL, whereas SAM showed the strongest reducing power in the FRAP assay (0.530 nm at 100 µg/mL). In the phosphomolybdenum assay, SAA exhibited a high reducing potential (204.50 µg AAE/mg at 500 µg/mL). Antimicrobial evaluation indicated weak bacterial inhibition at lower concentrations, with moderate activity by SAM against Staphylococcus aureus and high inhibition by SAE against Escherichia coli at 1000 µg/mL. SAA showed significant antifungal activity (19.6 mm zone of inhibition against Candida albicans ). Both SAA and SAM were further evaluated for cytotoxicity against MCF-7 cells, where SAA was more potent (IC ₅₀  = 61.23 µg/mL) than SAM (IC ₅₀  = 131.89 µg/mL). GC-MS analysis of SAA identified 130 compounds dominated by triterpenoids (lupeol, 24.52%), sterols (γ-sitosterol, 10.70%), squalene (6.50%), phytol (4.96%), and γ-tocotrienol (3.10%). This preliminary investigation provides the first comprehensive insight into S. attenuata crude extracts, establishing SAA as the most bioactive fraction and a promising source of natural antioxidant, antifungal, and cytotoxic agent.