Research on phenolic composition, ascorbic acid content and antioxidant activity of Sea buckthorn berries.

The topic of the master thesis by I. Kozubovskaitė/ Research supervisor dr. Raimondas Raudonis; Lithuanian University of Health Sciences, Faculty of Pharmacy, Department of Pharmacognosy. – Kaunas. Research methods: Research of phenolic compounds, flavonoids, ascorbic acid and antioxidant activity of Hippophae rhamnoides L. The amount of phenolic compounds was determined by applying the spectrophotometric Folin – Ciocalteu method. The amount of flavonoids was evaluated spectrophotometrically by treating extracts with aluminium chloride solution in acetic acid medium. The antioxidant activity was determined by using ABTS and FRAP spectrophotometric methods. The aim: to research variations of phytochemical composition of different varieties of Hippophae rhamnoides L. and evaluate the antioxidant activity of extracts. Objectives of the study: to determine a general amount of phenolic compounds in sea buckthorn fruit by applying Folin-Ciocalteu method. To define a general amount of flavonoids and ascorbic acid in sea buckthorn fruit. To perform an antioxidant activity test of sea buckthorn fruit extracts by applying ABTS and FRAP methods. To perform a qualitative and a quantitative analysis of sea buckthorn fruit phenolic compounds by applying HPLS method. Results: The biggest total amount of phenolic compounds was found in the fruit extract of ‘Julia’ variety (1,65±0,01 mg GAE/g). The biggest amount of flavonoids was found in the fruit of ‘Podarok sadu’ and ‘Julia’ varieties (0,61±0,01 RE/g and 0,57±0,01 RE/g). Also ‘Julia’ variety fruit have the biggest amount of ascorbic acid (0,84±0,01%). The biggest amount of antioxidant activity was in the extract of ‘Julia’ using ABTS and FRAP tests (6,90±0,003 μmol TE/g and 13,80±0,01 μmol TE/g). In extracts were identified 8 phenolic compounds: gallic acid (6,49-14,16 µg/g), catechin (32,49-117,60 µg/g), quercetin-3-O-rutinozid (99,37-280,04 µg/g), quercetin-3-O-glucoside (19,54-32,51 µg/g), izoramnetin-3-O-rutinozid (101,81-229,63 µg/g), isorhamnetin-3-O-glucoside (89,19-195,00 µg/g), quercetin (2,68-5,09 µg/g), isorhamnetin (3,58-8,51 µg/g)