Eburicoic Acid from Curculigo orchioides Gaertn Attenuates the Enzymatic and Pathological Activities of Vipera russelli Phospholipase A2

Purpose: Curculigo orchioides Gaertn is a plant widely used in Siddha, Ayurveda, and Traditional Chinese Medicine. It contains bioactive compounds such as eburicoic acid with therapeutic potential. Snake venom phospholipase A 2 causes severe pathological effects, and plant-derived PLA 2 inhibitors are promising. However, the protective role of eburicoic acid (EA) against PLA 2 -induced toxicity remains unexplored. Aim: This study aimed to evaluate the inhibitory effects of EA from Curculigo orchioides on svPLA 2 enzymatic and pathological activities using integrated in silico, in vitro, and in vivo approaches. Methods: The eburicoic acid was extracted from Curculigo orchioides Gaertn. and subjected to molecular docking and molecular dynamics. Enzyme inhibition by svPLA2 assay, intrinsic fluorescence, and Circular Dichroism study. In vivo studies, such as svPLA2-induced edema and hemorrhagic activity assay, were conducted to analyze the anti-inflammatory effect of eburicoic acid. Results: Eburicoic acid from Curculigo orchioides Gaertn. inhibited the catalytic activity of svPLA2 in a dose-dependent manner with an IC 50 value of 6.7± 0.4 μM, the isolated compound eburicoic acid neutralized the svPLA 2 activity. The interaction between the inhibitor and svPLA 2 increased the relative intrinsic fluorescence intensity and appears to shift the far UV-CD spectrum. Eburicoic acid decreased svPLA2-induced mouse paw edema from 168 to 128% and neutralized indirect hemolytic activity from 96 to 8%. Furthermore, eburicoic acid reduced the hemorrhagic effect caused by the synergistic interaction of svPLA2 and the neurotoxic non-enzymatic peptide (VNTx-II). MD simulation showed that APO, OLA, and EBA complexes remained stable over 100ns, with minimal structural fluctuations and no significant conformational changes. Conclusion: The findings indicate that bioactive compounds from C. orchioides , which inhibit V. russelli sPLA2, highlight the potential of plant-derived molecules as effective alternatives for enhancing anti-venom and anti-inflammatory therapies that are safer and more readily available. Keywords: secretory phospholipase A2 group IIA, anti-venom, bioactive compound, phytochemicals, hemorrhage, anti-inflammatory