Bioactivity guided isolation of antidiabetic and antioxidant compound from Xylocarpus granatum J. Koenig bark

The present study was designed to identify antidiabetic and antioxidant constituents from ethanol bark extract of a medicinally important mangrove plant Xylocarpus granatum J. Koenig, using in vitro bioactivity-guided fractionation. The repeated fractionation of X. granatum ethanol bark extract (XGEB) by silica gel column chromatography yielded a compound with strong antidiabetic and antioxidant potential. The bioactive compounds likely to be present in the XGEB fraction were identified by FT-IR, ¹H & ¹³C NMR and MS analysis and determined as a limonoid derivative Xyloccensin-I, by comparing spectral data with the literature reports. The isolated compound demonstrated excellent in vitro antidiabetic potential IC₅₀ values of 0.25 and 0.16 mg/ml, respectively for α-amylase and α-glucosidase inhibition study. The antioxidant potential assayed by DPPH, ABTS, superoxide and hydrogen peroxide scavenging studies exhibited that the isolated compound could scavenge these free radicals with IC₅₀ values of 0.041, 0.039, 0.096 and 0.235 mg/ml, respectively. Further, in silico study was performed to find the antidiabetic activity of Xyloccensin-I by docking it against α-glucosidase enzyme. The study demonstrated that Xyloccensin-I have satisfactory interactions and binding energies when docked into target which further confirms the possible mode of antidiabetic action of the isolated compound. The bioactivity assays further asserts the antidiabetic and antioxidant efficacy of the isolated compound which strongly suggests that Xyloccensin-I holds promise in the pharmaceutical industry. The results from this study provide new mechanistic evidence justifying, at least in part, the traditional use of X. granatum extract for antidiabetic and antioxidants activities.