Variability of the antibacterial potential among analogue diterpenes against Gram-positive bacteria: considerations on the structure–activity relationship

Abstract

The search for new antibacterial agents and a better comprehension of substances with antimicrobial behavior is mandatory nowadays due to the serious public health problem of infection diseases. In the present work, 30 diterpenes were studied, with 2 natural derivatives, named ent-16-kauren-19-oic acid and ent-pimara-8(14),15-dien-19-oic acid, and 28 semi-synthetic derivatives. The natural diterpenes were isolated from Mikania glomerata and Viguiera arenaria, respectively. All diterpenes were submitted to antimicrobial assays against six different Gram-positive microorganisms to better understand the structure–activity relationship of antimicrobial diterpenes. The semi-synthetic derivatives were all obtained from the two natural derivatives by structural modifications, mainly esterification reactions. Both natural derivatives, together with the derivative ent-8(14)-pimaren-19-oic acid, displayed the most relevant antibacterial activities, with minimal inhibitory concentration (MIC) values that were less than 10 μg mL–1 for most pathogens; thus, they were considered promising antimicrobial agents. Moreover, in light of the hypothesis of Urzúa and colleagues, several considerations about the structure–activity relationship of antimicrobial diterpenes could be stated.

Cytotoxic and genotoxic effects of the ent-kaurenoic acid and ent-kaurenoic acid enriched Mikania glomerata extract in V79

“…The KA content in the extract was determined after the development and validation of a reverse-phase HPLC analytical method, which corresponded to about 48% of KA content in KAMg (Moreira et al 2016). The KA samples used in this work were obtained from the leaves of M. glomerata just as described by Soares et al (2019).…”