Comparative in vitro antioxidant activities of aqueous and n-hexane extracts of Cucurbita maxima seed

Cucurbita maxima (Pumpkin, Cucurbitaceae) seed is reportedly used traditionally for the treatment of diarrheal. The aim of this study was to evaluate the in vitro antioxidants, total tannins, phenolics contents and compare the antioxidant potentials of n-hexane and aqueous Cucurbita maxima seed extracts. Cucurbita maxima seed expressed significant 2,2, diphenyl-1-picrythdrazyl scavenging activities at 6.25 – 1000 mg/mL with IC₅₀ values of 104.01 mg/mL, 29.27 mg/mL and 26.78 mg/mL for n-hexane, aqueous and vitamin C respectively. The hydroxyl radical scavenging activities of the n-hexane and aqueous seed extract of Cucurbita maxima were significantly lower at higher concentrations compared with that of vitamin C. However, the hydrogen peroxide scavenging activities of aqueous seed extract (50.03 mg/mL) was higher than n-hexane extract (129.20 mg/mL). Furthermore, the total antioxidant capacities of n-hexane (22.08 mg/mL) and aqueous seed extract (11.03 mg/mL) of Cucurbita maxima were found to be higher than that of vitamin C (134.46 mg/mL). The aqueous extracts (658.33±380.08 mg QE/g) total tannins were not significantly different from the n-hexane extract (468.33±102.55 mg QE/g) while the n-hexane extract contains significantly higher total phenolics (2.93±1.25 mg GAE/g) compared with the aqueous extract (0.19±0.04 mg GAE/g). The study concludes that aqueous and n-hexane seed extracts of Cucurbita maxima (pumpkin) possess significant in vitro antioxidant activities.