Ramifloraolides A - D, four highly oxygenated picrotoxane-type sesquiterpenoids from the stems of Baccaurea ramiflora and their antithrombotic activity.

A phytochemical investigation of the ethanol extract from air-dried stems of Baccaurea ramiflora led to the isolation of four highly oxygenated picrotoxane-type sesquiterpenoids, ramifloraolides A - D (1-4). Their structures were elucidated by comprehensive spectroscopic data (HRESIMS, IR, 1D, and 2D NMR), and their absolute configuration of them were unambiguously determined by single-crystal X-ray diffraction. Structurally, all compounds possess a unique [4.3.0] bicyclic core along with a characteristic γ-lactone. Notably, compound 1 is a picrotoxane sesquiterpenoid incorporating a rare oxygen bridge and a pentadecolactone. Compounds 2-4 possess a five-membered ether ring and the pentadecolactone, while ramifloraolides C (3) and D (4) were nor-picrotoxane. Then, the isolated phytochemicals were evaluated for antithrombotic activity in vivo. Interestingly, compounds 1 and 2 displayed potent antithrombotic activity at 30 μM in a zebrafish model. Additionally, 1 and 2 demonstrated certain antithrombotic effects in a mouse model of thrombosis. This marked the first report on the anti-thrombotic activity of picrotoxane-type sesquiterpenoids. Furthermore, network pharmacological and molecular docking analysis revealed potent target of those compounds associated with thrombotic disease. These finding initially demonstrate the potential of picrotoxanes as naturally derived antithrombotic lead compounds, and highlight the significant research values of sesquiterpenoids from the Baccaurea genus for comprehensive exploration of their application in antithrombotic therapy.