Cytotoxic activity and cell cycle analysis of quinoline alkaloids isolated from Haplophyllum canaliculatum Boiss.

Bioassay-guided fractionation of Haplophyllum canaliculatum Boiss. (Rutaceae) extract resulted in isolation of five quinoline alkaloids: 7-isopentenyloxy-gamma-fagarine, atanine, skimmianine, flindersine and perfamine. This is the first isolation of these compounds from this endemic species. The antitumor activity of these five isolates was evaluated against RAJI, Jurkat, KG-1a, HEP-2, MCF-7, HL-60 and HL-60/MX1 tumor cell lines. The highest cytotoxic effect was observed on acute lymphoblastic leukemia cell lines. 7-Isopentenyloxy-gamma-fagarine, atanine, skimmianine and flindersine exhibited very high cytotoxicity against the RAJI cell line with IC(50) values of 1.5, 14.5, 15.6 and 14.9 microg/mL, respectively and 7-isopentenyloxy-gamma-fagarine, atanine and skimmianine exhibited very high cytotoxicity against the Jurkat cell line with IC(50) values of 3.6, 9.3 and 11.5 microg/mL, respectively. 7-Isopentenyloxy-gamma-fagarine was also highly cytotoxic against the MCF-7 cell line (IC(50) = 15.5 microg/mL), while atanine, skimmianine, flindersine and perfamine showed moderate to low activity against these cells. All alkaloids had moderate to low cytotoxicity against KG-1a and HEP-2. Investigation of the toxic potential of the alkaloids on HL-60 and HL-60/MX1 showed a significantly higher effect against HL-60/MX1, a multidrug-resistant cell line, compared with the control etoposide (p < 0.05). In all cytotoxicity experiments, peripheral blood mononuclear cells (PBMC) were used as a control for normal hematopoietic cells. Flow cytometry analysis of the compounds resulted in the arrest of cell cycle progression at the sub-G1 phase of the RAJI and Jurkat cell lines in a dose-dependent manner. According to computational analyses, the similar cytotoxic trend in the cell lines could be indicative of the fact that these compounds may act through parallel mechanisms. Georg Thieme Verlag KG Stuttgart, New York.