This study investigated the active components and the anti-
tumor efficacy and mechanisms of the
flavonoids from Docynia delavayi (Franch.) Schneid. (DDS). MTT assay was used to examine the growth inhibitory effects of the four
flavonoids, including
chrysin,
quercetin,
naringenin, and
avicularin that were isolated from the rhizome of DDS, on human
hematomas cell (HepG2), esophageal
carcinoma cell (EC109), human cervical
adenocarcinoma cell (Hela), human
colon adenocarcinoma cell (SW480), and African green monkey kidney cell (Vero cells). The anti-
tumor mechanism of
chrysin on HepG2 was further investigated by the methods of fluorescence staining, flow cytometry, and immunoblotting. The results showed that the inhibitory activity of
chrysin was much stronger than the other three
flavonoids on HepG2, EC109, Hela, and SW480 cells for 48 h treatment in vitro. Moreover, no inhibiting effect of
chrysin on the proliferation of normal cells (Vero cells) was observed. Further study revealed that
chrysin caused HepG2 cell shrinkage, membrane blebbing, and apoptotic body formation, all of which were typical characteristics of apoptosis programmed cell death. Flow cytometric analysis demonstrated that
chrysin increased the sub G0/G1 population, which indicated the increased cell apoptosis, thus preventing cells from entering the S phase as the population in G2/M or S phase declined; whereas in G0/G1 phase, it increased. In addition, immunoblot results showed that
chrysin significantly increased the expression levels of
caspase-3 and Bax
proteins, and it decreased the expression level of
B-cell lymphoma/
leukemia-2 (Bcl-2)
protein. These findings indicate that
chrysin is the major
flavonoid present in DDS, and it induces HepG2 cell death via apoptosis, probably through the participation of
caspase-3, Bax, and Bcl-2
proteins.