THE CHEMICAL CHARACTERISTICS AND ANTIBACTERIAL ACTIVITY OF GREEN TEA (Camellia sinensis), STINGING NETTLE (Urtica dioica) LEAVES AND THE BLEND

Abstract

Infusions such as teas (made from Camellia sinensis L.) and tisanes (made from herbs, spices, or other plant parts) have been used for centuries in traditional therapy. In the study, green tea (Camellia sinensis) and stinging nettle (Urtica dioica) are mixed in different proportions (1.5:1.5, 1.8:1.2, 2.1:0.9, 2.4:0.6, 2.7:0.3) to obtain an optimum formulation of a blended tea using DOE and based on sensory characteristics that were further investigated as potential antibacterial agents. Green tea, U. dioica leaves and the selected tea blend was subjected to organic solvent extraction (methanol and ethanol) as well as aqueous extraction. Major phytochemicals (phenols, flavonoid, and tannin) along with the antioxidant activity (DPPH radical scavenging activity, TAC, and FRAP) were determined for the prepared extracts. The antibacterial properties were evaluated by the agar well diffusion method. Minimum inhibitory concentration was evaluated by the micro well dilution method. The sensory analysis was carried out for brew appearance, aroma, color and overall acceptance of five tea infusions, and from the result, sample C (green tea: U. dioica leaves; 2.1:0.9) was found superior to other samples. Among the plant extracts tested, the blend extracts in methanol gave the highest TPC (387.11mgGAE/g), TFC (167.57mgQE/g), Tannin (47.68mgGAE/g), DPPH radical scavenging activity (98.32%), TAC (15.38mgAAE/g), and FRAP (15.12AAE/g) (p<0.05). The best antimicrobial actions were observed in the blend extract against the five clinical isolates. The most effective activity was proven against S. aureus with a maximum ZOI of 18mm, 18mm, and 10mm in methanol, ethanol, and aqueous solvent respectively, and a minimum inhibitory concentration value of 50µg/ml against E. faecalis at 3.2mg/ml. The study concluded that green tea and stinging nettle are in fact more effective as mixtures (2.1:0.9), implying that the combined preparation can synergistically enhance antioxidant as well as antibacterial properties