Li-Xia Zhao,Mao-Jun Jiang,Jia-Jun Hu,Yue-Li Zou,Shuang Gao,Ying Fu,Fei Ye
Protoporphyrinogen oxidase (PPO) is an important target for discovering new herbicides that interfere with the synthesis of porphyrin. To discover new PPO inhibitors with improved biological activity, a series of new diphenyl ethers containing tetrahydrophthalimide were designed and synthesized. Among them, J6.1 (IC50 = 4.7 nM) and J6.3 (IC50 = 30.0 nM) show higher maize (Zea mays L.) PPO inhibitory activity than the commercial herbicides oxyfluorfen (IC50 = 117.9 nM) and flumioxazin (IC50 = 157.1 nM). The greenhouse herbicidal activity of J6.3 is comparable to that of oxyfluorfen, and it is greater than that of flumioxazin. Even at a dose of 300 g ai ha−1, cotton (Gossypium hirsutum L.) and peanut (Arachis hypogaea L.) show greater tolerance to J6.3, suggesting that J6.3 could be used for further development of new herbicide candidates in those fields. In addition, molecular docking has been used to further study the mechanism of action of J6.3. The results show that the introduction of a nitro group and tetrahydrophthalimide into the diphenyl ether structure is beneficial to biological activity.
Tao Liao,Junping Liu,Yuefang Sun,Liqiang Zou,Lei Zhou,Chengmei Liu,Netsanet Shiferaw Terefe,Wei Liu
The inhibitory effects of ascorbic, citric, ferulic and salicylic acid on pear polyphenol oxidase (PPO) were investigated in model and food system. All four organic acids showed strong inhibition effect in model system. However, compared to model system, inhibitory effect of PPO in pear puree was quite different. Ascorbic acid showed a much weaker effect in pear puree compared to the model system. Similarly, ferulic and salicylic acid had limited inhibitory effect in pear puree. Interestingly, the inhibition of PPO activity was not correlated to browning control in pear puree. Ascorbic acid in low concentration was not effective in inhibiting PPO activity in pear puree but exhibited an excellent anti-browning effect. The study indicates that the level of PPO activity is not always a good indicator of susceptibility to browning in foods. Overall, ascorbic acid showed the strongest inhibition of browning and increased the total phenolic content of pear puree.
It has been revealed that some polyphenols can prevent enzymatic browning caused by polyphenoloxidase (PPO). Apigenin, widely distributed in many fruits and vegetables, is an important bioactive flavonoid compound. In this study, apigenin exhibited a strong inhibitory activity against PPO, and some reagents had synergistic effect with apigenin on inhibiting PPO. Apigenin inhibited PPO activity reversibly in a mixed-type manner. The fact that inactivation rate constant ( k ) of PPO increased while activation energy ( E a ) and thermodynamic parameters (Δ G , Δ H and Δ S ) decreased indicated that the thermosensitivity and stability of PPO decreased. The conformational changes of PPO were revealed by fluorescence emission spectra and circular dichroism. Atomic force microscopy observation suggested that the dimension of PPO molecules was larger after interacting with apigenin. Moreover, computational docking simulation indicated that apigenin bound to PPO and inserted into the hydrophobic cavity of PPO to interact with some amino acid residues.
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