This article describes the isolation of L-catechin and a novel synthesis of L-catechin bioorganic complexes in water. The formation of the complex is deduced from the UV–visible spectra, which shows that the successive formation of complex occurs in a ratio of 1:1 (metal/ligand) stoichiometric. Five new complexes were synthesized by the reaction of ligand L-catechin with bioorganic metal ions such as Zinc (Zn2+), Copper (Cu2+), Ferrous (Fe2+), Magnesium (Mg2+), Calcium (Ca2+). The composition of the complexes was characterized by elemental analysis, FTIR, mass spectrometry (MS) and 1H NMR spectrometric techniques. The antioxidant activity of the complex was evaluated using the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide radical scavenging method whereas; the anti-inflammatory activity was evaluated using the bovine serum albumin method. L-catechin bioorganic complexes were evaluated against three human cancer cell lines using breast, lungs, and leukemia cancer cell lines. In the following work, we have successfully demonstrated that the metal complexed flavonoids were much more effective free radical scavengers, than the free flavonoids.