Chromatographic investigation of phytoconstituents in milk yam (Ipomoea digitata L.) tubers

Background: Milk yam commonly called Ksheervidhari is a perennial climber; its tubers are an integral crude drug in different Ayurvedic formulations as well as folkloric medicine. It is used as antidiabetic, restorative, carminative, expectorant, galactagogue, stomachic, and appetizer. Objective: The present study is done with the aim of identifying the maturity stage of milk yam tuber containing maximum concentration of umbelliferone – a coumarin present in the tubers. Materials and Methods: Umbelliferone present in immature tubers (6 months after planting), overmature tubers (36 months after planting), and tubers at optimum maturity (21 months after planting) was assessed using high-performance liquid chromatography (HPLC) and high-performance thin-layer chromatography (HPTLC) analysis. Results: HPLC and HPTLC techniques revealed the presence of umbelliferone and it was quantified to be higher in over mature tubers (0.44 and 0.42 μg/g, respectively), followed by optimally mature (0.31 and 0.22 μg/g, respectively) and immature tubers (0.20 and <0.11 μg/g, respectively). Conclusion: The study reveales that developmental stages affect umbelliferone concentration in milk yam tubers and it increased as the plant ages.