# Monoterpene indole alkaloids from the aerial parts of Ophiorrhiza brevidentata and their immunological activities

## TL;DR

This study isolated 10 new alkaloids from Ophiorrhiza brevidentata and found some have strong anti-B cell activity.

## Contribution

Discovery of 10 new monoterpene indole alkaloids with a unique polycyclic structure and immunological activity.

## Key findings

- Compound 1 has a novel fused 6/5/6/7/6 polycyclic structure.
- Compounds 3–5 and 9 strongly inhibit B cell proliferation with IC50 values between 3.6–9.1 µM.
- These compounds show high selectivity indices (SI > 10).

## Abstract

Phytochemical study of the EtOAc extract of Ophiorrhiza brevidentata resulted in the discovery of 10 new monoterpene indole alkaloids (1–10), along with 13 known compounds (11 − 23). Compound 1 possess an unprecedented skeleton consisting of fused 6/5/6/7/6 polycyclic systems. The structural characterization of these compounds was achieved using Nuclear Magnetic Resonance, Mass Spectrometry and Quantum Chemical Calculations. Compounds 3–5 and 9 exhibited strong inhibition on lipopolysaccharide-induced B cell proliferation with IC50 values ranging from 3.6–9.1 µM with excellent selectivity indices (SI > 10).

The online version contains supplementary material available at 10.1007/s13659-025-00575-y.