Validation of tribal claims through ethnopharmacological investigation of Indigofera tsiangiana Metcalf (Fabaceae)

Indigofera tsiangiana, commonly known as birdsville indigo (family Fabaceae), is an underexplored medicinal plant investigated for its bioactive compounds, cytotoxicity, antimicrobial, anthelmintic, antioxidant potential and thin-layer chromatographic profile. Plant specimens were collected from the Mahanadi River region of the Athgarh Forest Division, Odisha, where the Sabar community traditionally uses it as a medicinal agent, though documentation remains scarce. The present study investigated the availability of bioactive compounds and in-vitro biological activities of the whole plant of I. tsiangiana using n-hexane, acetone, ethanol and aqueous extracts. Qualitative phytochemical screening revealed the consistent presence of tannins and saponins in all extracts, while flavonoids were detected only in the aqueous extract and alkaloids were present in ethanol, acetone and aqueous extracts. Quantitative analysis showed that the whole plant contained 14.37 mg/100 g of tannins, 2.64% saponins, 1.01 mg/100 g total phenols and 0.046 mg/100 g flavonoids. Anthelmintic activity against Eisenia fetida demonstrated pronounced dose-dependent effects. At 100 mg/ml, the aqueous extract caused paralysis within 40 min and death within 1 h, while the ethanolic extract induced paralysis in 1 h 5 min and death in 3 h 32 min; acetone extract showed comparatively weaker activity with no mortality up to 24 h at the same concentration. Antibacterial activity evaluated against Streptococcus pyogenes and Streptococcus pneumoniae revealed that the ethanolic extract exhibited the highest efficacy. In agar well diffusion assays, the ethanol extract produced zones of inhibition of 29 ± 0.02 mm (S. pyogenes) and 33 ± 0.05 mm (S. pneumoniae) at 200 mg/ml, followed by aqueous (21 ± 0.06 mm and 25 ± 0.01 mm) and acetone extracts (19 ± 0.04 mm and 20 ± 0.08 mm). Disc diffusion assays showed a similar trend. MIC analysis indicated complete inhibition of S. pyogenes by ethanol extract at >25 mg/ml and of S. pneumoniae at >50 mg/ml, whereas aqueous extracts failed to inhibit growth at all tested concentrations. TLC profiling revealed multiple bioactive constituents with Rf values ranging from 0.33 to 0.97 and TLC-based antioxidant assays confirmed strong antioxidant activity in ethanol and acetone extracts. Cytotoxicity assessment using the brine shrimp lethality assay showed concentration-dependent mortality, with 100% lethality at 83.3-166.6 mg/ml for ethanol and n-hexane extracts, comparable to vincristine sulphate. Overall, the findings demonstrate that I. tsiangiana is a rich source of bioactive phytochemicals exhibiting significant anthelmintic, antibacterial, antioxidant and cytotoxic activities.