Anabolic Effect of Zinc-Containing Marine Alga (Fucus) Extract on Bone Components in Rat Femoral Tissues in vitro and in vivo

The effect of zinc-containing marine algae on bone components in the femoral tissues of rats in vitro and in vivo was investigated. Marine alga (fucus, Phaeophyceae) contained a comparatively higher concentration of zinc (3.16%). Water-extracted marine alga solution was prepared at concentrations of 10-7 to 10-5 M zinc. The femoral-diaphyseal and -metaphyseal tissues obtained from weanling rats were cultured for 24 h in Dulbecco’s modified Eagle’s medium containing either vehicle or zinc-containing marine alga water extract (10-7 to 10-5 M zinc) in vitro. The presence of zinc-containing marine alga extract caused a significant increase of calcium content, alkaline phosphatase activity, and deoxyribonucleic acid (DNA) content in the femoral-diaphyseal and metaphyseal tissues. This anabolic effect was completely blocked by the presence of a chelator of zinc ion or an inhibitor of protein synthesis. Moreover, when weanling or elderly rats received daily an oral administration of zinc-containing marine alga suspension (5.0 mg zinc/100 g body weight) for 8 or 10 days, respectively, the femoral-diaphyseal and -metaphyseal components were significantly elevated. This administration produced a significant increase in the serum and femoral zinc concentrations of elderly rats (50 weeks old). The present study demonstrates that zinc-containing marine alga materials have an anabolic effect on bone metabolism in vitro and in vivo, suggesting a useful role for zinc-containing food on the prevention of bone loss with increasing age.