Structure of constituents isolated from the bark of Cassipourea malosana and their cytotoxicity against a human ovarian cell line.

Three aromatic compounds, 2α,3α-epoxyflavan-5,7,4'-triol-(4ß â†’ 8)-afzelechin (1), 2ß,3ß-epoxyflavan-5,7,4'-triol-(4α → 8)-epiafzelechin (2), and methyl 4-ethoxy-2-hydroxy-6-propylbenzoate (3), as well as eight known compounds (4-11) were isolated from the bark of Cassipourea malosana (Rhizophoraceae). Their structures were determined on the basis of an analysis of spectroscopic data. The in vitro cytotoxic activities of these compounds against human ovarian cancer cell line TOV21G were evaluated. Most compounds showed little activity; however, the methyl derivatives of flavan dimers (1a and 2a) showed higher activity (IC50 value of 30.3 and 75.4 µM) than parent compounds 1 and 2.

Chemical studies on the roots of Uvaria welwitschii.

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.

Hydroxyespintanol and schefflerichalcone: two new compounds from Uvaria scheffleri.

A chemical investigation of the petroleum ether extract and chloroform extract of the root of Uvaria scheffleri Diels (Annonaceae) led to the isolation of two new compounds, named hydroxyespintanol (1) and schefflerichalcone (2), together with eight known compounds (3-10). The structural elucidation of compounds 1 and 2 by spectroscopic studies is described. The cytotoxicity of the isolated compounds against human promyelocytic leukemia HL-60 cells was studied. Among these, 2'-hydroxy-3',4',6'-trimethoxychalcone (5) exhibited cytotoxicity (IC(50) 12 microM), and espintanol (3), which was the main ingredient, also showed some cytotoxicity (IC(50) 44 microM).

Induction of apoptosis in human promyelocytic leukemia cell line HL-60 by C-benzylated dihydrochalcones, uvaretin, isouvaretin and diuvaretin.

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 G1 phase and the appearance of a sub-G1 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.

Cytotoxic C-benzylated dihydrochalcones from Uvaria acuminata.

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.