br It has been reported in the literature that naphthoquinone
It has been reported in the literature that 1,4-naphthoquinone-
Corresponding author at: Department of Medicinal Chemistry, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran. E-mail addresses: [email protected], [email protected] (M. Khoshneviszadeh).
Fig. 1. Some natural and synthetic 1,4-naphthoquinone derivatives as anticancer agents.
triazole hybrids showed various biological activities, including anti-mycobacterial , anti-Trypanosoma cruzi , antileishmanial  and antimalarial .The first studies of 1,4-naphthoquinone-1,2,3-triazole hybrids considered to be anticancer agents was reported by Olivera Group. Among the tested derivatives, two compounds demon-strated good cytotoxic activities against K562 and HL-60 cells. It was stated that the cytotoxicity is mediated through apoptosis in HL-60 cells and Quizartinib arrest in S-phase in K562 cell line [26,27]. da Silva Júnior Group screened several -lapachone, nor-a-lapachone and 1,4-naph-thoquinone containing 1,2,3-triazole moiety for their cytotoxic activ-ities against different cancer and normal cell lines. The obtained results indicated that some of them were considerably active with IC50 values below 2 μM [28,29]. Further studies to expand the trypanocidal and antitumor activities resulted in naphthoquinone-based 5-iodo-1,4-dis-ubstituted-,1,4- and 1,5-disubstituted-1,2,3-triazoles with improved cytotoxic activities against cancer cell lines. The most potent molecule showed IC50 in the range of 0.41–1.23 μM . More recently, Mal-lavadhani and his co-workers investigated novel series of menadione linked to 1,2,3-triazole ring with promising cytotoxic activities against A-549, DU-145, Hela and MCF-7 cell lines. In particular, one of the most potent compounds showed greater potency than menadione as a parent molecule, and standard Tamoxifen against MCF-7 cell line . A summary of aforementioned points on anticancer naphthoquinone-triazole hybrids is depicted in Scheme 1.
In continuation of our researches on anticancer drug discovery, we designed 1,4-naphthoquinone-1,2,3-triazole hybrid compounds bearing different benzyl moieties (Scheme 1) as cytotoxic agents and after the synthesis, cytotoxicity of the derivatives was evaluated against three human cancer cell lines. In order to discover the mode of cytotoxicity,
the effect of three selected compounds on the cell cycle phases was studied.
2. Materials and methods
2.1. Chemicals and reagents
All reagents and chemicals were acquired from commercial sources and used without further purification. 1,4-Naphthoquinone and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) were purchased from Sigma-Aldrich (Saint Louis, MO, USA) while penicillin/ streptomycin were product of Invitrogen (San Diego, CA, USA). Fetal bovine serum (FBS), phosphate buffered saline (PBS) and trypsin were obtained from Biosera (Ringmer, UK). Roswell Park Memorial Institute (RPMI) 1640 medium was purchased from PAA (Austria). Doxorubicin and cisplatin were from EBEWE Pharma (Unterach, Austria) and Mylan (Athens, Greece), respectively. Dimethyl sulfoxide (DMSO) was pur-chased from Merck (Darmstadt, Germany). The chemical names given for the prepared compounds are according to the IUPAC system as defined by ChemBioDraw Ultra 14.0 software.
Chromatographic separations were done on a silica gel column by flash chromatography (Kieselgel 40, 0.040–0.063 mm; Merck). Melting points were taken on a hot stage apparatus (Electrothermal, Essex, UK) and were reported uncorrected. Infrared spectra were recorded on a Perkin-Elmer spectrometer (KBr disk) (PerkinElmer, Waltham, MA, USA). 1H and 13C NMR spectra were recorded on a Bruker Avance 300
Scheme 1. Structures of some 1,4-naphthoquinone-1,2,3-triazole hybrids with cytotoxic activity against different cell lines.
spectrometer (300 and 75 MHz for 1H and 13C NMR, respectively), with tetramethylsilane (TMS) as internal reference. Chemical shifts (δ) are given in ppm and coupling constants (J) in Hertz. Mass spectra were obtained using an Agilent spectrometer (9575c inert MSD; Agilent Technologies, Santa Clara, CA, USA). Elemental analysis was done by Microanalytical Department, Central Laboratories for Research, Shiraz University of Medical Sciences and was within 0.4% of the calculated value.
2.3. General procedure for the synthesis of 2-(prop-2-ynylamino)
1,4-Naphthoquinone (1 mmol) was dissolved in 10 ml ethanol fol-lowed by slow addition of propargyl amine (5 mmol) at room tem-perature. The reaction was stirred for 1 h. Completion of the reaction was checked by thin layer chromatography (TLC). Then after, the mixture was filtered and washed with cold ethanol and diethyl ether.