EXCLI J EXCLI Journal 1611-2156 Leibniz Research Centre for Working Environment and Human Factors 2020-2579 10.17179/excli2020-2579 Doc984 Letter to the editor Recent insights into the biological functions of apigenin Kim Jae Kwang 1 Park Sang Un * 2 Division of Life Sciences and Bio-Resource and Environmental Center, Incheon National University, Incheon 22012, Korea Department of Crop Science, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon, 34134, Korea *To whom correspondence should be addressed: Sang Un Park, Department of Crop Science, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon, 34134, Korea; Tel.: +82-42-821-5730, Fax: +82-42-822-2631, E-mail: supark@cnu.ac.kr 06 07 2020 2020 19 984 991 27 06 2020 02 07 2020 Copyright © 2020 Kim et al. 2020

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Dear Editor,

Apigenin (4′,5,7-trihydroxyflavone) belongs to the group of flavonoids positioned on the backbone of 2-phenylchromen-4-one (2-phenyl-1-benzopyran-4-one) and is most extensively allocated in herbs, vegetables, and fruits (Shankar et al., 2017[46]; Sharma et al., 2019[47]). Biosynthetically, apigenin is obtained from the phenylpropanoid pathway and also from the flavone synthesis pathway (Forkmann, 1991[12]) The pathway of phenylpropanoid begins from the aromatic amino acids L-phenylalanine or L-tyrosine, both products of the shikimate pathway (Herrmann, 1995[18]).

In several recent studies, it has been shown that apigenin has a number of valuable bioactive functions, including antibacterial, antiviral, antiproliferative, anti-inflammatory, antioxidant, antiangiogenic, and anticancer activities (Kowalczyk et al., 2017[25]; Nabavi et al., 2018[35]; Ghițu et al., 2019[14]).

From the results of several in vivo and in vitro studies and clinical trials, apigenin has been shown to be an effective curative treatment for rheumatoid arthritis, autoimmune disorders, Parkinson's disease, Alzheimer's disease, and several types of cancers (Tang et al., 2017[51]; Salehi et al., 2019[43]). Here, we summarize the key findings of the biological and pharmacological actions of apigenin (Table 1(Tab. 1); References in Table 1: Ahmad et al., 2019[1]; Ai et al., 2017[2]; Amiri et al., 2018[3]; Britto et al., 2017[4]; Charalabopoulos et al., 2019[5]; Chen et al., 2017[7], 2019[8], 2020[6]; Choi et al., 2018[9]; Dean et al., 2018[10]; Feng et al., 2017[11]; Ganai, 2017[13]; Han et al., 2017[15]; Hassan et al., 2017[16]; He et al., 2020[17]; Huang et al., 2020[19]; Jiang et al., 2018[20]; Jiao et al., 2019[21]; Jing et al., 2019[22]; Kang et al., 2018[23]; Ketkaew et al., 2017[24]; Lee et al., 2019[26]; Li et al., 2017[28], 2019[29], 2020[27]; Liu et al., 2018[30]; Lu et al., 2019[31]; Malik et al., 2017[32]; Mirzoeva et al., 2018[33]; Mrazek et al., 2019[34]; Nelson et al., 2017[36]; Pang et al., 2019[37]; Qiu et al., 2019[38]; Quan et al., 2020[39]; Rašković et al., 2017[40]; Ren et al., 2018[41]; Safari et al., 2018[42]; Sánchez-Marzo et al., 2019[44]; Sang et al., 2017[45]; Sharma et al., 2018[48]; Siddique and Jyoti, 2017[49]; Stump et al., 2017[50]; Thangaiyan et al., 2018[52]; Tong et al., 2019[53]; Wang et al., 2017[54], 2018[56], 2019[55]; Wu et al., 2017[57]; Xu et al., 2018[58]; Zare et al., 2019[59]; Zhang et al., 2017[61], 2018[63], 2019[62], 2020[60]; Zhao et al., 2019[64]; Zhong et al., 2017[65], 2018[66]; Zhou et al., 2019[67]).

 Acknowledgements

This research was supported by Golden Seed Project (213006051WTE11) funded by the Ministry of Agriculture, Food and Rural Affairs (MAFRA), the Ministry of Oceans and Fisheries (MOF), the Rural Development Administration (RDA), and the Korea Forest Service (KFS), Republic of Korea.

 Conflict of interest

The authors declare no conflict of interest.

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