Gastroprotective Effect of Polypeptide-K Isolated from Momordica charantia's Seeds on Multiple Experimental Gastric Ulcer Models in Rats

Peptic ulcer disease is a multifactorial disorder and is the most significant public health concern nowadays. Previous study showed that essential oil extracted from Momordica charantia's seed exhibited gastroprotective effect. However, the evidence for the gastroprotective effect of its active compound, polypeptide K (PPK), remains unclear. This study aimed to examine the preventive effect of PPK against different experimental gastric lesions models in rats. The possible gastroprotective effect of PPK was assessed in hydrochloride ethanol- and indomethacin-induced gastric ulcer models in Sprague Dawley rats and was further evaluated macroscopically and microscopically. Pyloric ligation experiments were used to investigate gastric secretion. Oral administration of PPK at all concentrations (10, 25, and 50 mg/kg) showed significant (p < 0.05) reduction in total area of lesion in both hydrochloride ethanol- and indomethacin-induced gastric ulcer models. The highest inhibition rate was seen in PPK dose of 50 mg/kg with 64.9% and 72.2% on hydrochloride ethanol and indomethacin models, respectively. Microscopically, PPK preserved the normal architectures of the gastric tissues from being damaged by hydrochloride ethanol and indomethacin. Further, in the pyloric ligation studies, PPK significantly (p < 0.05) decreased the ulcer area where the highest protection was exhibited by 50 mg/kg with 70% inhibition rate. Moreover, all concentrations of PPK also significantly (p < 0.05) enhanced the gastric wall mucus secretion. Collectively, this study demonstrated the gastroprotective effect of PPK on hydrochloride ethanol- and indomethacin-induced gastric ulcer models. The possible mechanism might be associated with enhanced mucus secretion and thus lowering the total acidity.