Thorough Characterization of Two Sessein Derivatives with Potential Biological Activity

TL;DR

Scientists modified a natural compound called sessein to create two new derivatives and found that these changes affected their antimicrobial properties.

Contribution

The study introduces two new sessein derivatives and shows how structural changes influence antimicrobial activity.

Findings

Two sessein derivatives were successfully synthesized via acetylation and benzoylation of the C-12 hydroxyl group.

The acetylated derivative showed increased antimicrobial activity against Gram-negative bacteria.

Structural modifications were confirmed using UPLC-MS, FTIR, and NMR spectroscopy.

Abstract

The diterpene sessein, isolated from Salvia sessei, is a metabolite of interest due to its conjugated p-quinone system, δ-lactone ring, and phenolic hydroxyl in C-12. These functionalities make it an ideal starting point for reactivity studies and semi-synthetic derivatization. In this work, we report the obtainment of two derivatives by selective esterification of phenolic hydroxyl in C-12, through acetylation and benzoylation reactions under mild conditions and with high yields. The structures were characterized by UPLC-MS, FTIR, and NMR spectroscopy 1H, 13C, and 2D, which allowed to precisely confirm the modifications made in the derivatives. These results confirm that hydroxyl in C-12 constitutes a privileged site of reactivity within the royleanone family, consolidating sessein as a versatile nucleus for the generation of derivatives. Finally, the preliminary evaluation of the antimicrobial activity showed that sessein shows a broad spectrum of action against Gram-positive, Gram-negative, and Candida albicans strains. The acetylated derivative showed an increase in activity against gram-negative bacteria, while the benzoyl derivative had a loss of effect at the concentrations evaluated. These findings demonstrate that structural modifications influence the properties of the derivatives with respect to the compound sessein.

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