New dammarane and ursane-type triterpenoids from the flower of Ixora coccinea Linn.

Abstract

Two new esters of dammarane triterpenoids ixorene isovalerate (1), ixorene 3′,8′-dimethyloctanoate (2) and a new ursane-type triterpenoids Ixoroid acid (3) were isolated from the methanolic extract of flowers of Ixora coccinea Linn., along with the three known constituents. The structures of compounds 1 and 3 were elucidated on the basis of extensive 1D,2D NMR studies and mass spectrometry as 17β-dammara-12,20-diene-3β-isovelarate and 3β-hydroxy-18β-urs-12ene-29β-oic acid, respectively, whereas 2 was identified as 17β-dammara-12,20-diene-3β-3′,8′-dimethyloctanoate through ¹H NMR and mass spectral data. Compounds 1, 2, 4 and 5 were evaluated for their in vitro cytotoxic activity, which exhibited weak activity against the 3T3, PC3 and HeLa cell lines with the IC₅₀ value >30 μM. Antioxidant results of 1 – 5 revealed that only compound 5 showed antioxidant activity in DPPH radical scavenging inhibition with the IC₅₀ 1.31 × 10^− 6 ± 0.005 μm mL^− 1. Both activities are the first records of these isolated compounds from the flowers of Ixora coccinea Linn.

Keywords:

• dammarane triterpenoid
• ixorene isovalerate
• ixorene 3′,8′-dimethyloctanoate
• cytotoxic activity
• antioxidant activity

Acknowledgements

We gratefully acknowledge the Higher Education Commission (HEC) Govt. of Pakistan as the research work on Ixora coccinea was financial supported by HEC Project (P. No. 20–1-1480/R&D).