Bovine serum albumin binding, antioxidant and anticancer properties of an oxidovanadium(IV) complex with luteolin

• Luteolin coordinated to oxidovanadium(IV) through cis diol-O atoms.
• The CO and 5-OH groups of the flavonoid remained uncoordinated.
• The antioxidant effects of the ligand and the complex were similar.
• Promising agent against lung (A549) and breast (MDAMB231) tumor cells
• Protein binding studies confirmed the interactions of the complex with BSA.

Chemotherapy using metal coordination compounds for cancer treatment is the work of the ongoing research. Continuing our research on the improvement of the anticancer activity of natural flavonoids by metal complexation, a coordination compound of the natural antioxidant flavone luteolin (lut) and the oxidovanadium(IV) cation has been synthesized and characterized. Using different physicochemical measurements some structural aspects of [VO(lut)(H2O)2]Na·3H2O (VOlut) were determined. The metal coordinated to two cis-deprotonated oxygen atoms (ArO−) of the ligand and two H2O molecules. Magnetic measurements in solid state indicated the presence of an effective exchange pathway between adjacent vanadium ions. VOlut improved the antioxidant capacity of luteolin only against hydroxyl radical. The antitumoral effects were evaluated on MDAMB231 breast cancer and A549 lung cancer cell lines. VOlut exhibited higher viability inhibition (IC50 = 17 μM) than the ligand on MDAMB231 cells but they have the same behavior on A549 cells (ca. IC50 = 60 μM). At least oxidative stress processes were active during cancer cell-killing. When metals chelated through the carbonyl group and one adjacent OH group of the flavonoid an effective improvement of the biological properties has been observed. In VOlut the different coordination may be the cause of the small improvement of some of the tested properties of the flavonoid. Luteolin and VOlut could be distributed and transported in vivo. Luteolin interacted in the microenvironment of the tryptophan group of the serum binding protein, BSA, by means of electrostatic forces and its complex bind the protein by H bonding and van der Waals interactions.

The particular coordination mode of [VO(lut)(H2O)2]Na·3H2O, VOlut (lut, luteolin) through two cis-deprotonated oxygen atoms (ArO−) of luteolin, accounts for its poor antioxidant properties. Oxidative stress processes were active during cancer cell-killing on MDAMB231 breast and A549 lung cancer cell lines. Luteolin and VOlut could be distributed and transported in vivo.Figure optionsDownload as PowerPoint slide