Quantitative Composition of Phenolic Compounds in Apple Leaves during Vegetation Period

The aim of the research – investigation of quantitative composition variation of phenolic compounds during vegetation period in apple leaf samples of cultivar 'Ligol' grown in Lithuania and evaluation of the antioxidant activity of these extracts. The objectives of the research: 1. Evaluation of quantitative composition variation of phenolic compounds during vegetation period in extracts of apple leaf samples of cultivar 'Ligol'. 2. Evaluation of quantitative composition variation of flavonoids during vegetation period in extracts of apple leaf samples of cultivar 'Ligol'. 3. Evaluation of quantitative composition variation of proanthocyanidins during vegetation period in extracts of apple leaf samples of cultivar 'Ligol'. 4. Evaluation of the antioxidant activity in extracts of apple leaf samples of cultivar 'Ligol' using ABTS, DPPH, FRAP and TFPH UV-VIS spectrophometric methods in vitro. Research object and methodology: 'Ligol' apple leaves were harvested at different phenology phases between June and November 2013. The total phenolic compound, flavonoid and proanthocyanidin content in the apple leaf extracts was determinated with UV-VIS spectrophotometry. Antioxidant activity in apple leaf extracts determinated by DPPH, ABTS, FRAP, TFPH, and UV-VIS spectrophotometric methods in vitro. Results: the maximum total amount of phenolic compounds (235.15±10.34 mg/g) in apple leaf samples was established at the beginning of leaf growth (May 20). At the end of vegetation (November 4) the amount of phenolic compounds was 167.91±6.23 mg/g. The maximum total amount of flavonoids (27.37±0.86 mg/g) in apple leaf samples was established at the end of the vegetation period (November 4). The maximum total amount of proanthocyanidins (9.18±0.36 mg/g) in apple leaf samples was established at the stage of leaf aging (November 4). The strongest antiradical activity in apple leaf samples was established during leaf maturation phase (August 9) and at the end of maturarion period (November 4) (134.93±5.62 and 133.93±8.5 µmol TE/g accordingly. Conclusions: Apple leaves contain large amounts of phenolic compounds therefore they are a promising material for food supplements enriched with apple leaf extracts and for production of individual compounds with specific biological activity