Exploratory Evaluation of Anthocyanin Contents and Antioxidant Activity of Second Generation Purple Tea against Pigmented Fruits and Vegetables

Abstract

Anthocyanins are an important group of highly hydro-soluble pigments in most species of plants that are produced by secondary metabolism of plants through the pentose phosphate, shikimate and flavonoid pathways and are accumulated in cell vacuoles. They are polyphenols with strong antioxidant activity, which is largely responsible for some biological activities including prevention or lowering the risk of cardiovascular diseases, diabetes, arthritis and cancer. In fruits and vegetables anthocyanins are present in the form of glycosides. Anthocyanins have also been enhanced in tea through conventional breeding with the first generation purple tea cultivars already released for commercial utilization. Further purple tea improvement programme in Kenya has led to development of second generation purple tea plants focusing on further enhancement of anthocyanins content. A study involving second generation tea cultivars established in four experimental fields in Kenya namely; Timbilil, Kangaita, Nandi and Chesumot, compared levels of production of anthocyanins in the tea cultivars with purple-pigmented fruits and vegetables purchased from Kericho market. Total anthocyanin content was quantified by pH differential method using a UV- spectrophotometer, while radical scavenging activity of the tea extracts was assessed using 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH). There were significant (p≤0.05) differences, in the anthocyanins content among the tea varieties, fruits and vegetables. The anthocyanin contents in the tea cultivars ranged from 38.6 to 1037.0 mg/l, 169.7 to 501.0 mg/l, 78.3 to 682.1 mg/l and 19.7 to 876.9 mg/l, in Timbilil, Kangaita, Nandi and Chesumot, respectively. In the pigmented fruits and vegetables, the anthocyanin content was 1.5 and 425.3 mg/l for beetroot and red cabbage, respectively. The radical scavenging activity of second generation purple tea ranged from 82.8 to 91.5 % compared the pigmented fruits and vegetables that exhibited lower radical scavenging capacity of 1.14 to 45.3%. The observed enhanced level in the anthocyanins content and radical scavenging activity within some of the second generation purple teas have demonstrated the availability of improved cultivars with greater potential in antioxidant capacity and suitable alternative as super food for health conscious populations.