Uvaretin, isouvaretin and diuvaretin, cytotoxic C-benzylated dihydrochalcones isolated from Uvaria acuminata, displayed growth inhibitory effects against human promyelocytic leukemia HL-60 cells. We examined the mechanism of the cytotoxicity. From the morphological study by staining with Hoechst 33258, the cells treated with C-benzylated dihydrochalcones exhibited significant chromosomal condensation and nuclear degradation. The cell cycle analysis showed the accumulation of cells in the G 1 phase and the appearance of a sub-G 1 peak. These results suggest apoptotic cell death. Further, from the detection of DNA fragmentation and the activation of caspase-3, the biological hallmarks of apoptosis, these C-benzylated dihydrochalcones appeared to induce apoptosis against HL-60 cells. The cytotoxicity of uvaretin and diuvaretin was stronger than that of isouvaretin, which suggest that the 5-substitution of the 2-hydroxybenzyl group increased the cytotoxicity.

Two new C-benzylated dihydrochalcones, isochamuvaritin (1) and acumitin (2), have been isolated from the African medicinal plant Uvaria acuminata, together with the previously reported benzylbenzoate (3), uvaretin (4), isouvaretin (5), diuvaretin (6), and uvangoletin (7). The structural elucidation of compounds 1 and 2 in spectroscopic studies is described. C-Benzylated dihydrochalcones, especially 1, 2, 4, and 6, showed considerable cytotoxicity toward human promyelocytic leukemia HL-60 cells.

No abstract

Cytotoxic C-Benzylated Dihydrochalcones from Uvaria acuminata. -(ICHIMARU*, M.; NAKATANI, N.; TAKAHASHI, T.; NISHIYAMA, Y.; MORIYASU, M.; KATO, A.; MATHENGE, S. G.; JUMA, F. D.; NGANGA, J. N.; Chem.

A chemical investigation of the chloroform extract of the roots of Uvaria welwitschii (Annonaceae), an African traditional medicine taken for stomach ache, led to the isolation of eight new compounds, named welwitschins A-H (1-8), together with five known compounds (9-13). The structural elucidation by spectroscopic studies of the compounds isolated is described. All new compounds were flavonoids having a 2-hydroxy-3,4,6-trimethoxyphenyl moiety in the A-ring, and unsubstituted phenyl in the B-ring. Four of them (1-4) were monomeric flavonoids while the others (5-8) were dimeric flavonoids. The cytotoxicity of the isolated compounds against human promyelocytic leukemia HL-60 cells was investigated.