Cochliones A–D, four new tetrahydrochromanone derivatives from endophytic Cochliobolus sp.

Abstract

Four new tetrahydrochromanone derivatives, cochliones A–D (1–4), along with three known metabolites, 4-hydroxybenzaldehyde (5), 4-hydroxy-3-(3-methylbut-2-enyl) benzoic acid (6), and 2,2-dimethyl-2H-chromene-6-carboxylic acid (7), were characterized from the culture of Cochliobolus sp. IFB-E039, a fungus that resides inside the healthy root of Cynodon dactylon (Gramineae). The structures of 1–4 were accommodated by their spectral data (UV, IR, CD, HR-ESI-MS, ¹H and ¹³C NMR, ¹H–¹H COSY, HMQC, HMBC, and NOESY). The bioassay for the cytotoxic metabolite showed that cochlione C (3) inhibited human breast adenocarcinoma cell line (MCF-7) and human chronic myeloid leukemia cell line (K562) with IC₅₀ values of 21.99 and 4.59 μg/ml, respectively.

Keywords:

• tetrahydrochromanone derivatives
• cochliones A–D
• Cochliobolus sp.
• Cynodon dactylon
• cytotoxicity

Acknowledgements

This work was jointly supported by MOST (2009ZX09501-013 and 2007AA09Z446), NSFC (30821006), and MOE (20060284014).