Therapeutic Potential of Strobilanthes Species: A Critical Narrative Review of Phytochemical and Pharmacological Evidence

The genus Strobilanthes (Acanthaceae) comprises several hundred species distributed across tropical and subtropical Asia, several of which occupy a long-standing place in traditional medicine systems in Malaysia, Indonesia, India, China and Taiwan. Renewed scientific interest in this genus reflects a broader search for plant-derived leads against metabolic, neoplastic, microbial and inflammatory disease. This review synthesises phytochemical and pharmacological evidence on therapeutically relevant Strobilanthes species, with particular attention to Strobilanthes crispus, Strobilanthes cusia, Strobilanthes kunthiana, Strobilanthes glutinosus and Strobilanthes sarcorrhiza. Extracts and isolated constituents of these species, including indole alkaloids such as tryptanthrin and indirubin, flavonoids, phenolic acids and phytosterols, demonstrate antidiabetic, anticancer, antimicrobial, antiviral, anti-inflammatory, hepatoprotective and nephroprotective activities in preclinical models. The clearest translational evidence relates to indigo naturalis, a traditional preparation derived in part from Strobilanthes cusia, for which randomised clinical trials in psoriasis exist. Beyond this preparation, however, evidence for most species remains confined to in vitro and rodent studies, with considerable heterogeneity in extraction methods, dosing and outcome measures. Mechanistic work increasingly draws on network pharmacology and molecular docking to propose multi-target actions, particularly for cancer-related signalling and glycaemic control. The review identifies a persistent gap between promising preclinical pharmacology and the near-absence of standardised, adequately powered clinical trials across the genus. Future research priorities include pharmacokinetic characterisation, toxicological profiling, standardisation of plant material and extraction, and well-designed human studies. Strobilanthes species represent a chemically rich and pharmacologically diverse, but still substantially underexploited, source of candidate therapeutic agents.