The effects of ultraviolet B and C radiation on natural compounds of Malva neglecta Wallr. calli

It has been widely accepted that the increase of atmospheric pollutants and depletion of ozone, are the main causes for the increase of ultraviolet radiation on the earth. In the present study, the effects of UV-B and UV-C on of Malva neglecta calli were investigated. Besides mocuza whose wound healing effects is well known, the plant contains different flavonoides and anthocyanins which are known as good antioxidant and UV protectants as well. Explants from leaves were surface-sterilized and cultured on a modified B5 medium. After 7 days, the calli were emerged and were subcultured every 10 days. After 11 subcultures, the calli were exposed to different doses of UV irradiation as follows: 144, 288, 432, 576, 720, 864, 1296, and 1728 j/m2 for UV-B and 204, 408, 612, 816, 1020, 1284, 1836, and 2448 j/m2 for UV-C. The results showed that the flavonoids and anthocyanins contents (UV absorbing compounds) were increased significantly, compared with the control cells. The levels of apigenin and delphinidin in Malva neglecta cells decreased after exposure to UV-B and UV-C compared to the control calli. Malvidin increased in UV-B and UV-C exposed Malva neglecta cells. In addition, membrane lipid peroxidation increased by longer exposure to UV-C and UV-B, compared to the control cells. The results suggest that the effects of UV-B and UV-C on flavonoids and anthocyanins contents of callus-cultured Malva neglecta cells are not identical and therefore they should be differentially suggested as tools for increase of desigred components.