nutrients Review Natural Sources, Pharmacokinetics, Biological Activities and Health Benefits of Hydroxycinnamic Acids and Their Metabolites Matej Sova 1,* and Luciano Saso 2 1 Faculty of Pharmacy, University of Ljubljana, Aškerˇceva7, 1000 Ljubljana, Slovenia 2 Department of Physiology and Pharmacology "Vittorio Erspamer", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy;
[email protected] * Correspondence: matej.sova@ffa.uni-lj.si; Tel.: +386-1-476-9556 Received: 24 June 2020; Accepted: 22 July 2020; Published: 23 July 2020 Abstract: Hydroxycinnamic acids (HCAs) are important natural phenolic compounds present in high concentrations in fruits, vegetables, cereals, coffee, tea and wine. Many health beneficial effects have been acknowledged in food products rich in HCAs; however, food processing, dietary intake, bioaccessibility and pharmacokinetics have a high impact on HCAs to reach the target tissue in order to exert their biological activities. In particular, metabolism is of high importance since HCAs’ metabolites could either lose the activity or be even more potent compared to the parent compounds. In this review, natural sources and pharmacokinetic properties of HCAs and their esters are presented and discussed. The main focus is on their metabolism along with biological activities and health benefits. Special emphasis is given on specific effects of HCAs’ metabolites in comparison with their parent compounds. Keywords: diet; natural compounds; phenolic acids; hydroxycinnamic acids; metabolites; pharmacokinetic properties; biological activities; health effects 1. Introduction Our diet rich in plant food contains several health-beneficial ingredients. Among such ingredients, polyphenols represent one of the most important natural compounds. Phenolic compounds are members of probably the largest group of plant secondary metabolites and have the main function to protect the plants against ultraviolet radiation or invasion by pathogens [1,2].