Polyphenol Extract of Greens+™ Nutritional Supplement Stimulates Bone Formation in Cultures of Human Osteoblast-like SaOS-2 Cells

Abstract

Background and Aims: Oxidative stress has been associated with osteoporosis. Greens+™ is a commercially available nutritional supplement containing antioxidative polyphenols. Methods: To study the effects of greens+™ on differentiation and bone formation in human osteoblasts, the cells were cultured in Ham's F-12 medium in the absence or presence of varying concentrations of total free polyphenolic (TFP) in the extracts of greens+™. Results: Our results showed that the number of osteoblasts increased (p <. 05) compared to vehicle control after 2 and 4 days of treatment but were reduced (p <. 05) after 7 days of treatment with 1.2–2.0 mg greens+™ extract/ml (corresponding to 16.8–27.9 ng TFP expressed as gallic acid equivalent per millilter). Lower concentrations of greens+™ extract stimulated alkaline phosphatase activity at early time points (days 9 and 11), while higher concentrations at the later time point of day 13 resulted in a significant (p <. 05) inhibition, in a time (p <. 0001) and dose dependent (p <. 0001) manner. Greens+™ extract stimulated (p <. 05) the mineralized bone nodule formation in a dose and time dependent manner. Conclusions: The results showed that greens+™ extract influenced the maturation of osteoprogenitors toward progression to a bone-forming stage. Our data suggest that greens+™ may have beneficial effects on bone formation in vitro due to its antioxidant polyphenolic content and we can speculate that it may be a good alternative to drugs for the prevention of osteoporosis.

KEYWORDS:

• Greens+™
• nutritional supplement
• polyphenols
• human osteoblasts
• SaOS-2 cells
• bone formation
• alkaline phosphatase