Alkyl phloroglucinol derivatives from Syzygium levinei and their differentiation-inducing activity

Eleven compounds have been identified from the whole plants of Syzygium levinei (Myrtaceae) on the basis of spectroscopic analysis and chemical methods. Among these compounds, (Z)-1-(2,6-dihydroxy-4-methoxyphenyl)-oct-5-en-1-one (1), (3 E,7 Z)-1-(2,6-dihydroxy-4-methoxyphenyl)-deca-3,7-dien-1-one (2), and 1-(2-O-beta-D-glucopyranosyl-5,6-dihydroxy-4-methoxyphenyl)-octan-1-one (3) were characterized as new alkyl phloroglucinol derivatives, and 1-(2,6-dihydroxy-4-methoxyphenyl)-hexan-1-one (4) was identified as a new natural product. Compounds 1, 2, and 4 were found to inhibit the proliferation of leukemia K562 and HL-60 cells and also to induce the differentiation of K562 cells as determined by the appearance of matured morphology and the increase in the intracellular hemoglobin level.