title: Citrus limonin and its glucoside inhibit colon adenocarcinoma cell proliferation through apoptosis.
abstract: The current study was an attempt to elucidate the mechanism of human colon cancer cell proliferation inhibition by limonin and limonin glucoside (LG) isolated from seeds of Citrus reticulata. The structures of purified compounds were confirmed by NMR and quantified using HPLC. These compounds of more than 95% purity were subjected to proliferation inhibition assay using human colon adenocarcinoma (SW480) cells. The IC50 value of 54.74 and 37.39 μM was observed for limonin and LG, respectively at 72 h. Following confirmation of proliferation inhibition, pattern of DNA fragmentation and activation of caspase-3 of the cells treated with limonoids suggest involvement of apoptosis. Furthermore, reduction in the transcription ratio of bcl2/bax and induction of cytochrome c release from mitochondria to cytosol with treatment of limonoids confirm the activation of intrinsic apoptosis pathway. The activity of Bax and Bcl2 was confirmed through analysis of mitochondrial membrane potential and intracellular calcium in the cells treated with limonin and LG; the net content of caspase-8 was not affected by limonoids. Results of the current study provide compelling evidence on the induction of mitochondria mediated intrinsic apoptosis by both limonin and LG in cultured SW480 cells for the first time.
authors.affiliation: Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A&M University, College Station, Texas 77845-2119, United States.
authors.forename: Kotamballi N
authors.initials: KN
authors.lastname: Chidambara Murthy
authors.forename: G K
authors.initials: GK
authors.lastname: Jayaprakasha
authors.forename: Vinod
authors.initials: V
authors.lastname: Kumar
authors.forename: Keerti S
authors.initials: KS
authors.lastname: Rathore
authors.forename: Bhimanagouda S
authors.initials: BS
authors.lastname: Patil
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000201:enzymology / Q000503:physiopathology*; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002957:Citrus / Q000737:chemistry*; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000503:physiopathology*; D045304:Cytochromes c / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005960:Glucosides / Q000494:pharmacology*; D006801:Humans; D036701:Limonins / Q000494:pharmacology*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D005960:Glucosides; D036701:Limonins; D010936:Plant Extracts; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c; D053148:Caspase 3; C001546:limonin