Seasonal variation of total phenolic, antioxidant activity and minerals in fresh tea shoots [camellia sinensis var sinensis]

Seasonal variation of total phenolics, antioxidant activity and minerals in fresh tea shoots, consisting of one apical bud and two adjoining leaves sampled from Muradiye, Tuglali, Gundogdu, Enstitu 9, Hamzabey, Hayrat and Pazar 20 clones grown in Eastern Black Sea region in Turkey was investigated during three harvest season [May, July and September] in both 2006 and 2007 years. The total phenolics of all clones were lower in cool months of May in both years [average 33.00-90.27 mg GAE/g dry weight basis]. Thereafter, the levels of total phenolics increased throughout the warmer months from July to September. Antioxidant activity determined by p-carotene bleaching assay showed similar trends which increased from 1[st] harvest [May] to 3[rd] harvest [September]. All clones showed nearly 100% antioxidant activity at 2[nd] and 3[rd] harvest season which higher than standard synthetic antioxidant BHA [butylated hydroxyanisole]. However, seasonal variation of minerals [N, P, K, Ca, Mg, Na, Fe, Cu, Mn, Zn] showed different results according to clones used. These results seem to suggest that the harvest time is crucial to determining the antioxidant potential of fresh tea shoots

Total phenolic content, antioxidant and antimicrobial activities of some medicinal plants

Crude extracts from Inula aucherana, Fumaria officinalis, Crocus sativus, Vicum album, Tribulus terestris, Polygonatum multiflorum, Alkanna tinctoria and Taraxacum officinale were screened for their in vitro antioxidant and antimicrobial properties. Total phenolic content of extracts from these plants were also determined. Beta-carotene bleaching assay and Folin-Ciocalteu reagent were used to determine total antioxidant activity and total phenols of plant extracts. Antimicrobial activity was determined by using disk diffusion assay. Antioxidant activity and total phenolic content varied among plants used and Viscum album and Crocus sativus had the highest antioxidant [82.23%] and total phenolic content [42.29 mgGAE/g DW], respectively. The methanol extracts from Vicum album and Alkanna tinctoria showed antimicrobial activity against 9 out of 32 microorganisms, however extract from Inula aucherana showed antimicrobial activity against 15 out of 32 microorganisms. The results provided evidence that the studied plant might indeed be potential sources of natural antioxidant and antimicrobial agents