Grape extract protect against ionizing radiation-induced DNA damage

Grape extracts of different cultivars (Flame seedless, Kishmish chorni, Red globe and Thompson seedless) were investigated for in vitro antioxidant activity by ABTS assay, and compared protective efficacy against radiation-induced DNA damage. Seed extract showed the highest scavenging activity, followed by skin extract. Among different cultivars, 'flame seedless' skin extract showed higher scavenging activity followed by 'Kishmish chorni' skin extract. Grape extracts significantly prevented radiation-induced plasmid DNA damage. Super-coiled pBR 322 plasmid DNA (~93%) is completely converted to open circular (~97%) and linear (~2%) form at a dose of 150 Gy γ-radiation. Pretreatment with different grape extracts showed various degree of protection against radiation-induced DNA damage. Pretreatment with 1.6 µg grape skin extract of 'Thompson seedless' cultivar or grape flesh extract of any tested cultivar diminished the DNA strand breaks, and there was an increase in the super coiled form of DNA against 150 Gy of γ-radiation. However, pretreated pBR 322 DNA with the skin of 'Kishmish chorni' cultivars or seed of 'red globe' grape cultivars remained static during electrophoresis and confined in the groove on exposure to 150 Gy γ-radiation treatment. Co-treatment with the skin of red globe cultivar also partially confined plasmid DNA in the groove. The same trend was observed when plasmid DNA was exposed to 1.2 kGy γ-radiation. Our investigation revealed that anthocyanin present in grape skin was probably involved in radio protective activities through the formation of co-pigmentation with DNA. (author)