Progress in studies on meroterpenoids

Abstract

© 2020 Elsevier B.V. Current developments in the pharmaceutical industry indicate an increase in attention towards natural products and their analogues. This is primarily due to the availability and variety of natural organic structures that exhibit a wide range of biological activity. Unique among them is the several individual classes of natural products of mixed biogenic origin with isoprenyl fragments. These conjugated biosynthetic compounds are formed from isoprenyl fragments and fragments of other classes of natural metabolites (flavonoids, alkaloids, lipids, peptides, etc.) synthesized by other pathways. They are combined into one common group called meroterpenoids. Interest in meroterpenoids is due to their unique hybrid structure, where the terpene is either the main unit or is part of the compound as a functional group. Thus, they have diverse practical applications. For example, the biological properties of isoprenyl flavonoids are primarily associated with the properties of phenolic compounds, which are characterized by their antioxidant activity. Introduction of isoprenyl substituents, therefore, plays a modifying role, resulting in an increase in their lipophilicity and variation in their oxidation-reduction potential. Substances with antitumor activity, HIV-1 transcriptase inhibitors, immunomodulators, and antifeedants have been identified among meroterpenoids containing the quinone fragment. The presence of alkaloid and saponin meroterpenoids explains the medicinal properties of a number of plants used in medicinal chemistry around the world. The review considers progress in the synthesis and functionalization of isoprenoids in conjugate biosynthesis. A detailed classification of meroterpenoids is made in accordance with the role of the isoprenoid fragment and the class of compounds to which this fragment belongs. The schemes and mechanisms of conjugated biosynthesis are discussed. Particular attention is paid to the phenol-flavonoid derivatives, isoprenoid lipids, terpenic alkaloids and isoprenyl glycosides. Also, structure-property patterns are considered. In addition, issues related to the biological activity of various classes of meroterpenoids, which have found application in the therapy of cardiovascular diseases, diabetes, inflammatory processes, tumors, tropical diseases, etc., are discussed in detail.