Evaluation of antioxidant and antacid activities of crude methanol and peptide extracts of Momordica charantia, Luffa cylindrica, and Jatropha curcas

Abstract

Background: There are many uses for therapeutic-based compounds in the food and pharmaceutical industries, and natural products are one of the best sources of these compounds. Momordica charantia (Family Cucurbitaceae), Luffa cylindrica (Family Cucurbitaceae), and Jatropha curcas (Family Euphorbiacece) have been documented for various medicinal applications. Objective: This study aimed to assess the anti-ulcer and antioxidant properties of M. charantia, L. cylindrica and J. curcas extracts and their crude peptide. Methods: The plant samples were collected, identified, and authenticated at Forest Herbarium, Ibadan, Nigeria. The samples were allowed to air dry, were pulverized, and then were extracted using methanol. The peptidic principles were extracted using Dichloromethane: Chloroform: Water mixtures in the ratio 1:1:0.5 and concentrated in vacuo. The peptidic extracts were screened for peptide and peptide-related compounds by TLC bioautography using Ninhydrin, Pyridine, and modified G-250 reagents. The extracts were assessed for antioxidant (2,2-diphenyl-1-picrylhydrazyl, DPPH), free radical scavenging activity, total phenolic content (TPC), total flavonoid content (TFC), and antiulcer activity. The antiulcer activity was evaluated using the artificial gastric acid neutralizing activity. Results: It was observed that all M. charantia, L. cylindrica, and J. curcas and their crude peptide extracts contain phenols and flavonoids. The TPC values of the crude methanol extracts were greater than those of the corresponding peptide extracts for all three species. The TFC of M. charantia and L. cylindrica crude methanol extracts were lower than their crude peptide extracts, while the TFC of J. curcas crude methanol extract was higher than the TFC value for its crude peptide extract. The DPPH radical scavenging activity of the crude extracts and crude peptide extract of M. charantia, L. cylindrica, and J. curcas was low when compared to the standard (Gallic acid). The M. charantia crude peptide extract had the lowest IC50 value of 282.4 μg/mL, indicating that it had better scavenging efficacy compared to the other extracts that were examined, while the lowest IC50 value was obtained from J. curcas methanol extracts (411.7 μg/mL). The result from this study shows that M. charantia, L. cylindrica, and J. curcas and their crude peptide possess artificial gastric acid neutralizing activity, which implies that they can be used as antacids to reduce the acidity of the stomach. Hence, the plants were evaluated for their efficacy in managing peptic ulcers by their ability to reduce the acidity of the stomach by raising the pH of the stomach. This is the first report on the antacid potential of Momordica charantia, Luffa cylindrica, and Jatropha curcas in literature. Conclusions: The results from this study support the ethnomedicinal claims that M. charantia, L. cylindrica, and J. curcas can be used in the management of peptic ulcers, and these plants could serve as sources of lead compounds to produce natural antiulcer drugs. There were traces of the presence of linear peptides and cyclic peptides (cysteine-rich cyclotides). Keywords: Antiulcer, Antioxidant, Peptides, Momordica charantia, Luffa cylindrica, Jatropha curcas