Induction of apoptosis in U937 human leukaemia cells by the hexane fraction of an extract of immature Citrus grandis Osbeck fruits

• Published in: Food chemistry 2009-06, Vol.114 (4), p.1245-1250
• Main Authors: Lim, Hee-Kyung, Moon, Jeong Yong, Kim, Hana, Cho, Moonjae, Cho, Somi Kim
• Format: Article
• Language: English
• Subjects: Apoptosis; Bcl-2 family; Biological and medical sciences; Caspase-3 activity; cell proliferation; citrus fruits; Citrus grandis; Citrus grandis Osbeck; Citrus maxima; cytotoxicity; enzyme activity; Food industries; Fruit and vegetable industries; fruit extracts; Fundamental and applied biological sciences. Psychology; hexane; human cell lines; in vitro studies; leukemia; U937 human leukemia cells
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2008.10.088

The antiproliferative effect of an immature Citrus grandis Osbeck fruit extract was investigated using U937 human leukaemia cells. Maximum cytotoxicity was observed using the hexane fraction (HF) of the extract. Cell death was dose-dependent ( IC 50 = ca. 60 μg/ml) and was characterised by chromatin condensation, apoptotic body formation, and DNA fragmentation. The induction of apoptosis was confirmed by caspase-3 activity assays and by immunoblotting using antibodies against Bcl-2, Bax, poly(ADP-ribose) polymerase (PARP), caspase-9, and caspase-3. The molecular mechanism underlying HF-induced apoptosis in U937 cells may involve a mitochondria-mediated signalling pathway, as demonstrated by an increase in the Bax/Bcl-2 expression ratio. Analyses of the HF by gas chromatography (GC) and GC-mass spectrometry (MS) tentatively identified 19 compounds, including γ-sitosterol (17.5%), 7-methoxy-8-(2-oxo-3-methylbutyl) coumarin (6.8%), stigmasterol (3.8%), and campesterol (3.4%). Together, our results provide the first evidence that the HF of an immature C. grandis Osbeck fruit extract induces apoptosis in U937 cells.