Polyphenols and their antioxidant activity in callus-cultured Malva neglecta cells under UV-B and UV-C irradiation

Malva neglecta Wallr is a perennial plant with high mucilage content, expectorant and cough-suppressing actions. The leaves and flowers of M. neglecta and some Malva species are used in traditional phytotherapy. Ultraviolet radiation in sunlight has diverse effects on humans, animals, plants and microorganisms. UV can cause damage to membrane by excitation of UV-B receptors, resulting in generation of reactive oxygen species and ultimately oxidative burst. Consequently organisms need to protect against and repair UV damage to survive in sunlight. Antioxidants are an important group of medicinal preventive compounds as well as being food additives inhibiting detrimental changes of easily oxidable nutrients. Polyphenols are commonly found in both edible and non-edible plants and they have been reported to have multiple biological effects, including antioxidant activity. In the present research callus cultures from leaf explants of M. neglecta were initiated in vitro, and their capacity to produce UV absorbing compounds was analyzed, after 90 minutes exposure to UV. The results showed that the levels of apigenin and delphinidin decreased after illumination with UV-B and UV-C, while Malvidin increased in UV-B and UV-C exposed Malva cells. The results demonstrate that polyphenols play important role in UV protection of Malva cells

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