A new series (6) of C5-curcuminoid derivatives (2E,6E-2,6-dibenzylidene-4-hydroxycyclohexanones) is described here with their evaluation for in vitro antiproliferative activities. Evaluation of 31 compounds against human A2780 (ovarian), C33A (cervix) and MDA-MB-231 (breast) cancer cell lines was performed to obtain structure activity relation data. The best performer was (2E,6E)-2,6-bis(3′-nitrobenzylidene)-4-hydroxycyclohexanone (6h) with IC50 values of 0.68 μM (A2780), 0.69 μM (C33A) and 0.92 μM (MDA-MB-231) compared to cisplatin with 1.30 μM, 3.69 μM and 19.13 μM, respectively. According to calculated physicochemical properties some members in series 6, namely (2E,6E)-2,6-bis[(4′-pyridinyl)methylene]-4-hydroxycyclohexanone (6p) [IC50 = 0.76 μM (A2780), 2.69 μM (C33A), 1.28 μM (MDA-MB-231)] seem to have improved bioavailability compared to curcumin. Selected members of series 6 were involved in circular dichroism spectroscopic measurements in order to determine their interaction with natural DNA. Based on these data, we conclude that these derivatives do not bind to DNA in vitro. A proposal is summarized based on mass spectrometric assessment for fingerprint analysis in biological research of such C5-curcuminoids.