Effect of spermidine and spermidine-supramolecular complexes on cell growth. Fibroblast cultures were exposed to spermidine salts (A) or spermidine-supramolecular complexes (B-F) for 24 (dark bars) and 48 h (light bars) and cell viability was evaluated by thiazolyl blue assay. A: Cells were treated with pure spermidine 3HCl (spermidine); B: Supramolecular complexes formed by spermidine with α-cyclodextrin (spermidine-aCD); C: Polymeric hyaluronan (spermidine-hyaluronate, HA); D: The natural biopolymer alginate (Spermidine-sodium alginate, Alg); E: Synthetic maleate copolymer (gantrez, Gz); F: Depolimerized HA salt (oligomeric hyaluronate, OHA). These data (mean ± SE, n = 3) are expressed as percentage (%) increase over cells treated with physiological saline (panels A and B) or the supramolecular complex alone without spermidine (panels C-F).