Introduction: Several diseases are associated with oxidative stress caused by free radicals. Current research focuses on finding naturally occurring antioxidants and antidiabetic agents of plant origin in treating oxidative-stress-related diseases. This study investigated the antioxidant and antidiabetic activities of methanolic and n-hexane essential oil extracts of Momordica charantia (bitter melon). Methods: The oils from the seeds of M. charantia were extracted with methanol and n-hexane, respectively, and their chemical constituents were analysed and quantified by GC-MS analyzer. The antioxidant activities of both oil extracts were measured by 1, 1-diphenyl-2-picryl-hydrazyl (DPPH), Hydroxyl radical (OH^.), and nitric oxide (NO) scavenging assays, while the antidiabetic activities were determined in vitro using the α-amylase and β-glucosidase assays.

Results: The GC-MS analysis revealed that methanol and n-hexane extracts of Momordica charantia seed oil are abundant in fatty acids such as pentadecanoic acid, octadecanoic acid, and cyclocoeicosanetriluoroacetic acid, and they both significantly demonstrated profound antioxidant and antidiabetic activity comparable to the reference antioxidant compound (ascorbic acid) and reference antidiabetic compound (acarbose). The essential oil from the methanol extract caused better inhibition of DPPH (89.69%), OH^. (75.12%), and NO (74.19%) at the highest concentration (500 μg/mL) investigated, despite both oils showing a dose-dependent antioxidant activity. The oils of the two solvents of M. charantia seeds also expressed dose-dependent inhibitory activity for α-amylase and β-glucosidase comparable to acarbose; however, the n-hexane oil extract demonstrated better antidiabetic activity for β-glucosidase (IC50 = 29.89 ± 0.051 μg/mL) compared to the methanolic oil extract (IC50 = 58.59 ± 0.047 μg/mL).

Conclusion: The results conclude that M. charantia seed oils are a good source of polyunsaturated fatty acids and afford an essential basis for the use of the oil in the treatment of oxidative-stress-related diseases like diabetes mellitus.