Abstract:
Padina minor Yamada, a brown alga which is found to be abundant on both sides
of the coastal area of the gulf of Thailand and the Andaman Sea was examined for
gastroprotective activity. The aqueous extract of P. minor (Aq. P) given orally to rats at the
doses of 100, 200 and 500 mg/kg significantly inhibited gastric ulcer formation induced
by (1) restraint water immersion stress (2) acid ethanol (HCl /EtOH), (3) indomethacin
and (4) histamine. In the pylorus-ligated rat experiment, the Aq. P caused a decrease of the
total acidity and an increase in gastric pH. Additionally, the Aq. P could not preserve the
mucus content in the gastric wall of rats with gastric ulceration induced by HCl /EtOH.
Results were obtained from the isolated guinea-pig right atrium experiment of which the
inhibitory effects of cimetidine (Histamine H2-antagonist) and the Aq. P on histamine-induced
chronotropic responses were determined and these results suggest that they share a similar
mechanism. The findings therefore indicate that P. minor possesses a gastroprotective activity,
which involves an anti-secretory mechanism mediated via histamine H2-antagonism.
The polysaccharide present in the P. minor is likely to contribute to the gastroprotective activity.
