Abietane Diterpenes of the Genus Plectranthus sensu lato

Abstract

Plectranthus (Lamiaceae), which—according to the latest systematic revision—includes three separate genera (Coleus, Plectranthus sensu stricto, and Equilabium), is a genus widely used in traditional medicine—mainly in the treatment of various ailments of the digestive tract, respiratory tract, and skin. Many species of Plectranthus s.l. have been shown to produce phenolic compounds and terpenes. Diterpenes, especially those of the abietane class, are the most studied group of secondary metabolites found in Plectranthus s.l., which is characterized by a significant structural diversity arising from the oxygenation and further rearrangement of the basic tricyclic abietane skeleton to a complete aromatization of the ring system. This review summarizes the known information on abietane diterpenes, showing their structures, sources, and biosynthesis. A classification of these compounds into nine groups, according to the arrangement of their ring C, is used. Royleanones, spirocoleons, and hydroquinones are the largest classes of abietane diterpenes, covering more than 70% of all the compounds reviewed.

Phytochemical Study and Antiglioblastoma Activity Assessment of Plectranthus hadiensis (Forssk.) Schweinf. ex Sprenger var. hadiensis Stems

“…Among all phytochemical classes, diterpenes are the most prominent biologically active group of secondary metabolites present in this genus, whose presence is considered as a chemotaxonomic marker [38]. In particular, abietane diterpenes have attracted attention regarding their biological activities, namely because of their antiproliferative, antitumoral, and/or cytotoxic potential [39,40].…”

Anti-inflammatory activities of Coleus forsteri (formerly Plectranthus forsteri) extracts on human macrophages and chemical characterization

“…The last compound 7α-formyloxy-6β-hydroxyroyleanone ( 7) is newly isolated from C. forsteri. It was previously found in other Coleus species (Gáborová et al, 2022). However, bioactivities of compound (7) were barely studied.…”

“…Plectranthus sensu lato is a large and widespread genus with an important range of ethnobotanical uses including medicinal purposes ( Lukhoba et al, 2006 ; Rice et al, 2011 ). Phytochemical studies have shown that this genus, including Coleus species, is a rich source of diterpenes exerting promising biological activities with abietane diterpenes as the most abundant group ( Abdel-Mogib et al, 2002 ; Gáborová et al, 2022 ). Interestingly, commercial extract of C. amboinicus was shown to inhibit maturation and release of inflammatory cytokine IL-1β through inhibition of nuclear factor NF-kB translocation ( Leu et al, 2019 ).…”

“…Horminone or 7α-hydroxyroyleanone ( 4 ) is a well-studied royleanone compound isolated from several Plectranthus s.l. Species exerting various bioactivities ranging from antitumoral and cytotoxic activities on various cancer cell lines to antimicrobial properties on MRSA and VRE as well as against Vibrio cholerae and Mycobacterium tuberculosis ( Gáborová et al, 2022 ). Horminone ( 4 ) inhibitory effect was also studied on KP metabolites and was shown to slightly regulate IDO1 activity and KYN and TRP production ( Becker et al, 2018 ).…”

“…Herein, 6β,7α-dihydroxyroyleanone ( 5 ) is newly isolated from C. forsteri while 7α-acetoxy-6β-hydroxyroyleanone ( 6 ) was previously isolated from C. forsteri methanolic extract ( Kubínová et al, 2013 ). Both compounds exert antimicrobial activity as well as cytotoxicity and inhibitory effect on the growth of human cancer cell lines ( Marques et al, 2002 ; Gaspar-Marques et al, 2006 ; Matias et al, 2019 ; Gáborová et al, 2022 ). It is noticeable that 7α-acetoxy-6β-hydroxyroyleanone ( 6 ) was shown to yield a potent antiproliferative activity against human lymphocytes with higher efficacy than the immunosuppressor cyclosporin ( Cerqueira et al, 2004 ).…”