Biochemical Studies on the Non-Enzymatic Antioxidants in the Potato (Solanum Tuberosum L.) Cultivars, and Cytotoxic Activity of Polyphenol Extract on Animal Cell Lines

Abstract

During aerobic metabolism in plants, the cellular compartments like chloroplast, mitochondria and peroxisomes generate a number of reactive oxygen species (ROS). Earlier it was regarded as the toxic by-products of aerobic metabolism. Currently, it is believed that ROS plays dual role; at low concentration they are involved in cell signalling and at high concentration they cause damage to various biomolecules, cellular structures and even cell death. As revealed by the numerous reports, a wide variety of antioxidants are associated with active defense under stress conditions as they can potentially scavenge the reactive oxygen species (ROS) to less harmful products. Various enzymatic and non-enzymatic antioxidants are involved overcoming the effects of ROS. The objectives of the study were a) estimation and comparison of ascorbic acid, phenolic and flavonoid contents; antioxidative capacity; sugar content; total protein content in different organs of potato cultivars at different stages of growth under field condition and also in the mature tubers under different storage conditions; b) To study the cytotoxic effects of polyphenolic extracts on animal cell lines namely, MCF-7 and RAW 264.7. It was observed that the ascorbate content was highest in mature leaves and lowest in mature tubers. The ascorbate content was found to be gradually decreased during storage (up to 60 days) under different experimental temperatures. Phenolic and flavonoid contents and overall antioxidative capacities were found to be at significantly higher level in the growing potato organs in comparison to the matured ones. Prolonged storage at room temperature, in particular, for a period of 60 days led to increase of total phenolic and flavonoid contents significantly in the harvested mature tubers. As expected, total protein content was found to be at higher in the young leaves as compared to the other organs. Protein content was found to be gradually decreased in the tubers during storage under different conditions. On the contrary, soluble sugar contents (both reducing and total sugars) were significantly increased during storage at low temperatures. This explains why potatoes becomes sweeter during storage. Apart from the select potato cultivars, all these assays were also done on some potato varieties collected from the local markets termed as ‘Market selection’ which included MS1 (purple coloured skin), MS2 (red coloured skin), MS3 (Agra variety), MS4 (Pahadi aaloo), MS5 (locally grown). MS1 and MS2 were found to contain higher levels of polyphenol, flavonoid and ascorbate contents. Polyphenolic extracts were to be effective in reducing the viability of the cell lines namely, MCF-7 (human breast cancer cell lines) and RAW 264.7 (Murine macrophage cell line).