Antioxidant capacity and contents of phenols, ascorbic acid, β-carotene and lycopene in lettuce

Abstract

The antioxidant activity of three lettuce varieties (Lactuca sativa L.) Emerald, Vera and Neva, cultivated in two kinds of protected spaces, a glasshouse and a plastic greenhouse, under controlled conditions, was determined. The content of antioxidant compounds: total phenols, flavonoids, L-ascorbic acid, β-carotene and lycopene, were determined in ethanolic extracts of the lettuce with spectrophotometric methods. The largest content of total phenols (78.98±0.67 mg GAE/g of dry extract) was found in ethanolic extract of the lettuce variety Neva cultivated in a plastic greenhouse, whereas the largest content of flavonoids (35.45±0.95 mg RU/g of dry extract) was displayed in the lettuce Emerald cultivated in a glasshouse. It was observed that the lettuce cultivated in the glasshouse contained a somewhat higher content of L-ascorbic acid than the lettuce same variety from plastic greenhouse. The content of lycopene in the examined lettuce is negligible, and the content of β-carotene is low. On the other hand, the high content of phenolic components causes favourable antioxidant properties found in all varieties of examined lettuce.

Određena je antioksidativna aktivnost tri sorte salate (Lactuca sativa L.) Emerald, Vera i Neva gajene u dve vrste zaštićenog prostora stakleniku i plasteniku pri kontrolisanim uslovima. Sadržaji antioksidativnih komponenti: ukupni fenoli, flavonoidi, L-askorbinska kiselina, β-karoten i likopen, određeni su u etanolskim ekstraktima salata spektrofotometrijskim metodama. Dobijeno je da najveći sadržaj ukupnih fenola (78,98 ± 0,67 mg GAE/g suvog ekstrakta) ima etanolski ekstrakt salate sorte Neva gajene u plasteniku, dok salata Emerald gajena u stakleniku ima najveći sadržaj flavonoida (35,45±0,95 mg RU/g suvog ekstrakta). Zapaženo je da salate gajene u stakleniku imaju nešto veći sadržaj L-askorbinske kiseline od salate istih sorti iz plastenika. Sadržaj likopena u ispitivanim salatama je zanemarljiv, a β-karotena je nizak. S druge strane visok sadržaj fenolnih komponenti uzrokuju dobre antioksidativne osobine nađene u svim sortama ispitivanih salata.