# 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.

## Key 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.