Inhibitory effects of L-3-phenyllacitc acid on the activity of mushnroom pholyphenol oxidase

Polyphenol oxidase (PPO), a kind of multiple functional oxidases, which was usually founded in many organisms including animals, insects, plants and microorganisms (Li et al., 2009; Seo et al., 2003; Yin et al., 2011a). PPO is the key enzyme involved in melanin synthesis, thus determined the color of mammalian skin, hair and fruit-vegetable browning (Ciou et al., 2011; Li et al., 2010; Lee et al., 2015). Browning occurred easily in fresh-cut or minimally processed fruits and vegetables, which were due to the presence of PPO in fruits and vegetables. When fruits and vegetables were damaged, the regional and localized distribution of the cells was destroyed, let the phenolic substances contact with polyphenol oxidase, then they ware polymerized to brown pigments and accelerated the browning of fruits and vegetables (Ciou et al., 2011; Pan et al., 2011). After the treatment of fruits and vegetables, the monophenol was produced to melanin through non-enzymatic reaction in the catalysis of PPO (Ismaya et al., 2011), polymerized to brown pigments, thus accelerated the browning of fruits and vegetables. Besides enzymatic browning, PPO was responsible for the reduction of the nutritional quality and market value of fruits and vegetables (Zhou et al., 2016).