New Eremophilenolides from Cacalia pilgeriana

Abstract

Five new eremophilenolides and a known sesquiterpene were isolated from the methanol extract of the roots of Cacalia pilgeriana. Their structures were identified as 1β-hydroxy-2β-methyl-senecioyloxyeremophil-7(11)-en-8β(12)-olide (1), 1β-hydroxy-2β-methylsenecioyloxy-8α-methoxyeremophil-7(11)-en- 8β(12)-olide (2), 2β-hydroxy-3β-methylsenecioyloxyeremophil-7(11)-en-8α(12)-olide (3), 2β,8β-dihydroxy-3β-methylsenecioyloxyeremophil-7(11)-en-8α(12)-olide (4) and 1β,8β-dihydroxy-2β,3α-diangeloyloxyeremophil-7(11)-en-8α(12)-olide (5) and caryolane-1,9β-diol (6) by spectroscopic methods including 2D-NMR techniques (¹H-¹H COSY, HMQC, HMBC) and HR-ESI-MS. The structure and relative stereochemistry of compound 1 were unequivocally established by X-ray diffraction analysis. Bioassays showed compounds 3 and 5 to possess strong cytotoxic activity in vitro against human leukemia cells (HL-60) (IC₅₀ < 15 μg mL^-1). The structure-activity relationship is discussed.

Cacalia pilgeriana - Compositae - eremophilenolides - sesquiterpenes - cytotoxic activity

References

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