The methanolic extract from the leaves of Tasmannia lanceolata and its principal constituent, polygodial, were found to show potent protective effects on ethanol-induced gastric lesions in rats, and the structure–activity relation of polygodial in gastromucosal protection

hyde, was originally isolated from the Polygonaceae plant Polygonum hydropiper, and subsequently from Warburgia ugandensis, W. stuhlmannii (Canellaceae), Pseudowintera colorata, and the Winteraceae plants Tasmannia lanceolata and Drymis winteri. Polygodial has a sharp peppery taste; it has been identified as a component in the hot taste of peppery spices in traditional Japanese cuisine, and can act as a vanilloid receptor agonist. Polygodial is known to exhibit various biological activities such as antihyperalgesia, potent attachment-inhibitory activity, insect antifeedant activity, antinociception, vasorelaxation action in vessels of rabbit and guinea pig, antiinflammatory and antiallergic activities, and antifungal and antimicrobial activities. The methanolic extract from the leaves of Tasmannia lanceolata and its principal constituent, polygodial, were found to show potent protective effects on ethanol-induced gastric lesions in rats, and the structure–activity relation of polygodial in gastromucosal protection was discussed. In the present study, the protective effects of polygodial against 0.6 M HCl, aspirin, and indomethacin-induced gastric lesions in rats and the effects of polygodial on gastric secretion in pylorus-ligated rats were examined. Sesquiterpenes having unsaturated dialdehyde structure including polygodial were recently reported to be agonists for vanilloid receptor-1 (VR1) and VR1 agonists such as capsaicin, resiniferatoxin and piperine protect the rat gastric mucosa against gastric ulcers in parallel with their sensory stimulating potencies. Whereas, a proton pump inhibitor, omeprazole, which is reported to have not only antisecretion of acid but also cytoprotective effects. We, therefore, examined the effect of polygodial on gastric lesions in comparison with capsaicin and omeprazole. In addition, to clarify the mechanism of action of polygodial in its strong inhibition of gastric lesions induced by ethanol, the roles of endogenous prostaglandins (PGs), nitric oxide (NO), sulfhydryl compounds (SHs) and vanilloid receptors were discussed.