Pigeonpea leaves in orthopedic diseases: bioactive metabolites, pharmacological actions and therapeutic potential

Pigeonpea leaves are derived from Cajanus cajan (L.) Huth [Fabaceae] and have long been used in traditional medicine to relieve blood stasis, swelling, pain, and musculoskeletal disorders. Flavonoids, stilbenes, phenolic acids, and triterpenoids are among the main metabolite classes identified in pigeonpea leaves. Experimental studies have linked pigeonpea leaf-derived materials to changes in inflammatory and oxidative-stress-related outcomes, microcirculation, and bone metabolism. Accordingly, their potential relevance to orthopedic disorders, including osteonecrosis of the femoral head, osteoporosis, osteoarthritis, and bone defects, has attracted increasing interest. Reported preclinical effects include changes in osteogenic differentiation, osteoclast formation, local blood supply, lipid metabolism, and inflammation- or oxidative-stress-related tissue injury. Among the investigated materials, total-flavonoid fractions, stilbene-rich extracts, the purified metabolite cajanin, and Tongluo Shenggu Capsule have shown biological activity in experimental models. This review summarizes the current research on pigeonpea leaves and their extracts, fractions, purified metabolites, and preparations in orthopedic disorders and discusses their possible mechanisms of action, potential relevance to orthopedic disorders, limitations of the available evidence, and remaining research gaps.