DETERMINATION OF SECONDARY METABOLITES, LD50 VALUE AND ANTIOXIDANT ACTIVITY OF SEED EXTRACT OF CUCURBITA PEPO LINN.

Abstract

Objective: To quantify the secondary metabolites, acute toxicity profile and the antioxidant potential of seed extract of Cucurbita pepo, an edible vegetable commonly used by people of Asian countries.

Methods: The methanolic seed extract of C.pepo (MSCP) was analyzed by HPLC and GC to determine various phytochemicals. Free radicals scavenging activity of MSCP was measured against DPPH, NO and superoxide radicals generated in vitro. Male Sprague Dawley rats were administered 200, 500, 1000, 2000, 2500 and 3000 mg/kg body weight of MSCP as a single dose or 3 equally divided doses within 8 hrs and observed for any abnormal symptoms of toxicity. Serum biochemistry and histopathological score in the ultra-sections of major organs were also determined.

Results: MSCP is found to contain alkaloids (4.09 mg), phenols (0.988 mg), flavonoids (1.223 mg) and terpenoids (2.144 mg) per gram of MSCP. The major flavonoid detected is quercetin. The MSCP is found to possess significant radical scavenging activity against DPPH (IC₅₀ – 40.8 µg/ml), NO (IC₅₀ – 38.70 µg/ml) and superoxide anions (IC₅₀ – 38.4 µg/ml) and the effect is comparable to that of the corresponding reference compounds ascorbic acid and rutin in terms of IC₅₀ value. By applying Karber's formula, 2975 mg/kg b.wt has been confirmed as the LD₅₀value of MSCP.

Conclusion: The medicinal property of C.pepo seeds may be attributed to the presence of flavonoids and phenolic compounds which counteract the free radicals responsible for various health complications. Based on the LD₅₀value, it could be recommended that 250 mg/kg b.wt can be administered to rats to study the therapeutic action of C.pepo seed extract.

 Key words: Cucurbita pepo, phytochemicals, free radicals, LD₅₀ value, scavenging activity.