Synthesis, antitumor screening and cell cycle analysis of novel benzothieno[3,2-b]pyran derivatives

Abstract

Three series of benzothiophene derivatives were designed and synthesized as cytotoxic agents. The compounds were subjected to in vitro antitumor screening at the National Cancer Institute (NCI), Bethesda, MD. The results of the single dose screening indicated that only the benzothieno[3,2-b]pyran series 3a-f exhibited potent and broad spectrum cytotoxic activity and was subjected to five dose cytotoxic screening. The most active compound in this study was 2-amino-6-bromo-4-(4-nitrophenyl)-4H-[1]benzothieno[3,2-b]pyran-3-carbonitrile (3e) with MG-MID GI 50 , TGI, and LC 50 values of 0.11, 7.94 and 42.66 mM, respectively. Compound 3e exhibited broad spectrum anticancer activity against a panel of 59 cell lines. To elucidate the underlying mechanism of compound 3e cytotoxic activity, we examined its effect on cell cycle progression and its ability to induce apoptosis using human colon adenocarcinoma cell line (HCT-116). The effect of compound 3e on the cell cycle progression indicated that exposure of HCT-116 cells to compound 3e for 24 and 48 h, induced a significant disruption in the cell cycle profile including time dependent decrease in cell population at G1 phase with concomitant increase in pre-G and G2/M cell population. Moreover, compound 3e induced time dependent increase in the percentage of early and late apoptotic and necrotic cell population. In conclusion, we were able to successfully design a new series of benzothieno [3,2-b]pyran derivatives with potent cytotoxic activity and their mechanism of cytotoxicity was examined.

Design, Synthesis, Antitumor activity, cell cycle analysis and ELISA assay for Cyclin Dependant Kinase-2 of a new (4-aryl-6-flouro-4H-benzo[4, 5] thieno[3, 2-b] pyran) derivatives.

“…A good result of the two compounds expressed in three parameters, median growth inhibition (GI50, concentration of compound that cause 50% inhibition in growth of cells), total growth inhibition (TGI, concentration of compound that cause 100% inhibition in growth of cells) and median lethal concentration ( LC50, concentration of compound that cause 50% loss of intact cells at the end of growth period), suggesting a promising anticancer motifs as shown in Table (2) and also summarized in Figure ( 3,4). From these result compound 4f (GI50 = 0.079 µmol, TGI= 1.21 µmol, LC50 = 3.48 µmol) was found to be more active than the structurally related compound 2-amino-6-bromo-4-(4-nitrophenyl)-4H [1]benzo-thieno[3,2-b]pyran-3-carbonitrile (3e) (GI50 = 0.11 µmol, TGI= 7.94 µmol, LC50 = 42.66 µmol) using HCT-116 cell line 13 . IC50 of compound 5d was found 0.3±0.05µg/ml and IC50 of compound 6 was found 0.15±0.01µg/ml while IC50 of Erlotinib reference was found 0.3±0.02 µg/ml using HT-29 cell line, when measured in VACERA Egypt expecting that compound 6 has a comparable anticancer activity as 4f compound Figure ( SAR result according to NCI 1-Compounds containing aminocyanogroup (4a-f) are more active than compounds containing aminoester group (5a-f) using the same cell line.…”

“…2-Presence of fluorine atom instead of bromine or chlorine at positions 6 (4a-f) results in higher anticancer activity 13 .…”

“…IR spectra of (3a-f) revealed the appearance of the conjugated C=O band at arrange of 1673-1680 cm -1 . 1 HNMR revealed the appearance of methine proton (=CH) at δ 8-8.09 ppm together with the introduced aromatic protons, 13 CNMR of this series showed C=O signal at δ 185 ppm. Further, IR spectra of (4a-f) revealed forked peak of NH2 at 3345-3460 cm -1 and CN group at 2190 cm -1 .…”

“…1 HNMR spectra of (4a-f) revealed the appearance of the CH aliphatic characteristic signal of the pyran ring at δ 5.03-5.10 ppm as well as an exchangeable singlet signal at δ 7.10-7.35 ppm corresponding to the NH2 protons. 13 CNMR spectra indicated the disappearance of C=O carbon signal around δ 188 ppm and the appearance of CH aliphatic of the pyran ring at δ 58-60 ppm and CN at δ 120 ppm. In addition, IR spectral analysis of Structures (5a-f) showed CH aliphatic at 2930-2890 cm -1 and carbonyl group of the ester at 1850 cm -1 beside forked peak of NH2 at 3300-3400 cm -1 .…”

“…Ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate (HA14-1) an antagonist for ant apoptotic Bcl-2 proteins was used to overcome drug resistance in cancer. Recently, screening anticancer activity of 2-amino-6-bromo-4-(4-nitrophenyl)-4H-benzo [4,5]thieno [3,2-b]pyran-3-carbonitrile using HCT-116 cell line produced a good anticancer activity and also proved to induce apoptosis at G0/G1 phase 13 .The present work is aimed towards construction of novel heterocyclic compounds of anticipated anticancer activity and to compare anticancer screening result of 2-amino-6-bromo-4-(4-nitrophenyl)-4H- [1]benzothieno [3,2-b]pyran-3-carbonitrile with our target compounds by replacing bromine atom at position 6 with fluorine atom which possess higher electronegativity, higher thermal stability and higher lipophilicity than bromine atom 14 . Figure 1.…”