Antioxidant capacities and cytostatic effect of Korean red pepper (Capsicum annuum L): A screening and in vitro study

Methanol extracts from 100 Korean varieties of red pepper (Capsicum annuum L) were obtained. Chromatic parameters (L*, a*, and b*) and total phenolic content were analyzed. By evaluation of total phenolic content and 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging based-antioxidant associated with surface color measurement, red pepper varieties were classified into four groups by hierarchical cluster analysis. Cultivars of 'PR-Sangsaeng', 'PR-Jijon', 'PREowoolrim', 'PR-Chambut', 'PAK37', and 'Hojanggoonbigalim" had high quantity of pigments and high phenolic content. These six cultivars also with higher levels of antioxidant might give an advantage to local growers in Korea. For further cytostatic activity evaluation, extracts from various parts including pericarp, seed, and stalk of cultivar 'PAK37' and 'Hojanggoonbigalim' were prepared. Four human cancer cells (HepG2, AGS, MCF-7, and HT-29) were used. The tumor cell growth inhibitory effect was evaluated by in vitro MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. High capsaicin content and antioxidant activity-containing red pepper stalk extract showed the strongest cytostatic activity. Tumor cell growth inhibitory activity was positively correlated with the capsaicin content. The anticancer potentials of various red pepper parts were in the following order: stalk > seed > pericarp. The data suggest that red pepper parts might have a promising health benefit against liver cancer, colon cancer and gastric cancer more than breast cancer.