# Grewiifopenes A–K, bioactive clerodane diterpenoids from Casearia grewiifolia Vent

## TL;DR

Researchers discovered eleven new bioactive compounds from a plant, some of which show strong cytotoxic and antibacterial properties.

## Contribution

The study reports the isolation and structural elucidation of eleven novel clerodane diterpenoids with notable bioactivities.

## Key findings

- Grewiifopenes A–K showed cytotoxic activity with IC50 values between 0.3 and 2.9 μM.
- Isocaseamembrin E and other compounds exhibited antibacterial activity against S. aureus and B. cereus.

## Abstract

Eleven novel clerodane-type diterpenoids, grewiifopenes A–K (1–4 and 12–18), along with nine known compounds (5–11, 19, and 20) were purified from the dichloromethane extract of the twigs and stems of Casearia grewiifolia Vent. (Salicaceae). Their spectroscopic data, including the NMR, HRESIMS, and electronic circular dichroism calculations were employed to completely characterize and elucidate the chemical structures and absolute configurations. The clerodane diterpenoids possessing a 6-OH group and no substitution at C-7 exhibited greater cytotoxic activity than others, with their IC50 values ranging from 0.3 to 2.9 μM. Isocaseamembrin E (7) exhibited antibacterial activity against Staphylococcus aureus, while isocaseamembrin E (7), corymbulosin X (8), caseargrewiin A (9), kurzipene A (10), and balanspene F (11) exhibited antibacterial activity against Bacillus cereus.

The online version contains supplementary material available at 10.1007/s13659-024-00475-7.