Calaxanthones A-C, three new xanthones from the roots of Calophyllum calaba and the cytotoxicity

Abstract

Three new xanthones, named calaxanthones A-C (1–3), along with 17 known xanthones (4–20) were isolated from the roots of Calophyllum calaba. Their structures were determined by spectroscopic analysis. All isolated compounds were evaluated for their cytotoxicity against five cancer cell lines (KB, HeLa S-3, HT-29, MCF-7 and HepG-2). Compound 3 showed potent cytotoxicity against all the five cancer cell lines with IC₅₀ values in the range of 0.82–5.04 μM. Furthermore, compound 6 showed potent cytotoxicity against KB, HeLa S-3 and HepG2 cells with IC₅₀ values of 7.06, 5.27 and 9.64 μM, respectively. Additionally, compound 7 showed potent cytotoxicity against KB cell with an IC₅₀ value of 4.62 μM.

Keywords:

• Calaxanthones A-C
• Calophyllum calaba
• xanthone
• cytotoxicity

Acknowledgements

The authors are grateful to the 90th anniversary of Chulalongkorn University Fund (Rat- chadaphiseksomphot Endowment Fund) for financial support. We also thank Dr Suttira Khumkratok, Walai Rukhavej Botanical Research Institute, Mahasarakham University, Mahasarakham 44000, Thailand for identification and deposition of the plant material.