Synthesis and structural characterization of new benzylidene glycosides, cytotoxicity against cancer cell lines and molecular modeling studies

This work describes the synthesis, structural characterization (by combined Fourier Transform Infrared - FTIR, 1H and 13C Nuclear Magnetic Resonance - NMR spectroscopy and High Resolution Mass Spectrometry - HRMS) and biological evaluation of a new series of glycosides designed from a benzylidene glucoside derived from eugenol (23) active against Candida glabrata. The mass accuracy between the calculated and found values observed in HRMS analyses were lower than 5 ppm, which are acceptable for proposing a molecular formula using this technique. We decided to keep the benzylidene group of 23, while changing either the saccharide unit (glucose or galactose) or the natural aglycone (eugenol, isoeugenol, dihydroeugenol or guaiacol) to check their influence in antifungal activity. Since the chemical modifications performed did not contribute to enhance the antifungal activity, the synthesized compounds (23–30) were further screened against four cancer cell lines (HeLa: cervix carcinoma; MDA-MB-231: breast carcinoma; T-24: urinary bladder carcinoma; and TOV-21G: ovarian carcinoma). The glucoside 27 showed promising activities (IC50 10.08–59.91 μM) against all the assayed cancer cell lines and higher values of selectivity index than doxorubicin, the control drug. The galactoside 28 demonstrated interesting results against HeLa, MDA-MB-231 and T-24 cells. This compound was active at 17.41 μM with a selectivity index greater than 13.7 against the HeLa cells, while doxorubicin was active at 10.01 μM with a selectivity index close to 1.5 considering this cell line. Further, we performed docking studies of these compounds with type II topoisomerase-DNA complex (TOP2) in order to try to explain their mechanism of action.