Colloidal bioactive nanospheres prepared from natural biomolecules, catechin and L-lysine

Recently, major attention has been devoted to exploring and increase biomedical applications of catechins by directly employing them as constituents of nano-vehicles. Here, (+)-catechin (CAT) was integrated with another benign biomolecule, L-Lysine (LYS) using formaldehyde (FA) via single-step Mannich condensation reaction and self-assembled supramolecular CAT-LYS networks were synthesized. By using various molar feed ratios of CAT, LYS, and FA (CAT:LYS:FA), different formulations of CAT-LYS particles were obtained as CAT-LYS-1(1:1:1), CAT-LYS-2(2:1:1), CAT-LYS-3(1:2:1), and CAT-LYS-4(1:1:2) particles. The CAT-LYS-4 particles with the highest gravimetric yield of 68.9 +/- 6.0% and 783.6 +/- 56.6 nm hydrodynamic diameter was chosen for bioactivity studies. The CAT-LYS-4 particles exhibited 190.4 +/- 1.3 mu g/mL CAT-equivalent antioxidant capacity at 1000 mu g/mL concentration with TEAC value of 0.24 +/- 0.01 mu mole Trolox-equivalent/g antioxidant activity. They showed 16.81 +/- 3.47% Fe(II) chelation capacity at 350 mu g/mL and 185.8 +/- 22.8 mu mole Fe(III) reducing power at 500 mu g/mL concentration. Moreover, the CAT-LYS-4 particles retained more than half of the alpha-glucosidase inhibition activity of CAT in particulate form. Besides, a 50-fold improvement was achieved on the hemolytic blood compatibility of CAT-LYS-4 particles upon integration of LYS into CAT backbone (4.7 +/- 1.2% at 250 mu g/mL) compared to hemolysis ratio of native CAT molecules. They did not show coagulation effects up to 500 mu g/mL concentration with > 94% clotting indices. Hence, the CAT-LYS particles with enhanced blood compatibilities and well-retained inherent bioactivities of their precursors in 3D colloidal particulate structures can serve as natural biocolloids for drug/active molecule transport applications in biomedicine.