Induction of apoptotic death of human hepatocellular carcinoma (HepG2) cells by ethanolic extract from litchi (Litchi chinensis Sonn.) flower

• First shows cytotoxic effects of litchi flower extract against human cancer cells.
• First shows that litchi flower extract could arrest cell cycle of HepG2 cells.
• First shows that litchi flower extract could trigger apoptosis in HepG2 cells.
• First shows the pro-apoptotic pathways for HepG2 cells treated by the extract.
• Litchi flower should have the potential to be exploited for treating liver cancer.

The cytotoxic activity of litchi (Litchi chinensis Sonn.) flower ethanolic extract (LFEE) against A549 (human lung adenocarcinoma), KB (human nasopharyngeal carcinoma), MCF-7 (human breast adenocarcinoma) and HepG2 (human hepatocellular carcinoma) cells was evaluated. LFEE exhibited better anti-proliferative action against HepG2 cells, which induced G2/M phase arrest and apoptosis in HepG2 cells. HepG2 cells treated with LFEE (0.3 mg/mL) enhanced expressions of p53, tBid, Bad and Bax, along with decreased expressions of Bcl-2 and Bcl-xL, and induced the release of cytochrome c from mitochondria to cytosol. That also accompanied by activation of caspases-3, -8 and -9 and cleavage of poly (adenosine diphosphate (ADP)-ribose) polymerase (PARP); furthermore, down-regulations of phosphoinositide 3 kinase (PI3K), Akt, Akt phosphorylation and Bad phosphorylation could also be observed. Five flavonoids (total amount, 101.07 mg/g dried extract (g DE)), nine phenolic acids (total amount, 55.07 mg/ g DE) and proanthocyanidin A2 (81.20 mg/ g DE) could be determined in LFEE.