Genus Justicia as a Source of Antidiabetic Agents: A Critical Review of Phytochemistry, Pharmacological Evidence, and Future Prospects with Special Reference to Justicia tranquebarensis

Abstract

Diabetes mellitus remains one of the most challenging global health burdens, with its prevalence increasing to rise and existing pharmacotherapies often limited by adverse effects, high cost, and declining long-term efficacy. These challenges have intensified interest in plant-derived antidiabetic agents, many of which offer multifaceted mechanisms, improved safety, and suitability for long-term management. Among such plant-based sources, the genus Justicia (Acanthaceae) holds significant ethnomedicinal relevance, particularly in traditional systems where numerous species are used for metabolic, inflammatory, and hepatic disorders. This review critically provides the current evidence on the phytochemistry and antidiabetic pharmacology of Justicia species, integrating data from in-vitro, in-vivo, and in-silico investigations. Reported constituents including, flavonoids, alkaloids, terpenoids, phenolics, and glycosides demonstrate potential for inhibiting carbohydrate-hydrolyzing enzymes, increasing insulin sensitivity, modulating oxidative stress, and improving glucose–lipid homeostasis. Several species such as J. adhatoda, J. gendarussa, J. spicigera, and J. procumbens exhibit substantial antidiabetic activity in preclinical models, supported by mechanistic insights from docking and molecular interaction studies. Special emphasis is placed on Justicia tranquebarensis, an underexplored species with preliminary reports indicating promising phytochemical richness and potential antidiabetic effects, yet comprehensive pharmacological validation is lacking. Overall, the genus Justicia represents a valuable reservoir of bioactive compounds with promising therapeutic prospects against diabetes. This review highlights current advances, existing limitations, and future research needs including compound isolation, mechanistic clarification, pharmacokinetic evaluation, and translational studies to position J. tranquebarensis and related species as strong candidates for next-generation phytopharmaceutical development.