Antioxidant and antibacterial properties of green, black, and herbal teas of Camellia sinensis

Abstract

Background:The role of non-polymeric phenolic (NP) and polymeric tannin (PT) constituents in the antioxidant and antibacterial properties of six brands of green, black, and herbal teas of Camellia sinensis were investigated.Materials and Methods:Total phenolic content (TPC) and ascorbic acid equivalent antioxidant capacity (AEAC) were assessed using the Folin-Ciocalteu and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays, respectively. Minimum inhibitory dose (MID) against Gram-positive Micrococcus luteus, Staphylococcus aureus, and Bacillus cereus, and Gram-negative. Escherichia coli, Salmonella typhi, and Pseudomonas aeruginosa was assessed using the disc-diffusion method. Teas were extracted with hot water successively three times for one hour each time. The extracts were fractionated using Sephadex LH-20 column chromatography to obtain the NP and PT constituents.Results:Extraction yields ranged from 12 to 23%. Yields of NP fractions (70–81%) were much higher than those of PT fractions (1–11%), suggesting that the former are the major tea components. Ranking of antioxidant properties of extracts was green tea>black tea>herbal tea. For all six teas, antioxidant properties of PT fractions were significantly higher than extracts and NP fractions. Extracts and fractions of all six teas showed no activity against the three Gram-negative bacteria. Green teas inhibited all three Gram-positive bacteria with S. aureus being the least susceptible. Black and herbal teas inhibited the growth of M. luteus and B. cereus, but not S. aureus. The most potent were the PT fractions of Boh Cameron Highlands and Ho Yan Hor with MID of 0.01 and 0.03 mg/disc against M. luteus.Conclusion:Results suggested that NP constituents are major contributors to the antioxidant and antibacterial properties of teas of C. sinensis. Although PT constituents have stronger antioxidant and antibacterial properties, they constitute only a minor component of the teas.

Antioxidant and antibacterial properties of some fresh and dried Labiatae herbs

“…[4] Extracts (300 μl) were introduced into test tubes wrapped with aluminium foil, followed by 1.5 ml of FC reagent (10 times dilution) and 1.2 ml of sodium carbonate (7.5%, w/v). After incubating for 30 min in the dark, absorbance was measured at 765 nm.…”

“…[4] Different dilutions of extracts (1 ml) were added to 2 ml of DPPH (5.9 mg per 100 ml methanol). Absorbance was measured at 517 nm after 30 min.…”

Suggested mechanism for the effect of sweeteners on radical scavenging activity of phenolic compounds in black and green tea

“…The different types of teas (white, green, oolong and black), which all originate from the leaves of Camellia sinensis, are classified according to the degree of fermentation process; both white and green teas are unfermented. Oolong tea is semi-fermented, while black tea is fully fermented (Chan et al 2011). The basic types of tea have different quality characteristics including appearance, aroma, taste and color.…”

Antioxidant, anti-tyrosinase and anti-quorum sensing activities of four mangrove tree species vs. green tea

“…The oven-dried (OD) and microwave-dried (MD) leaves were extracted using the hot water method (Chan et al, 2011(Chan et al, , 2012a. Samples (0.3 g) were ground and extracted with 50 ml of boiling water with continuous swirling at 100 rpm in an orbital shaker for one hour.…”