The protective effect of alfalfa (Medicago sativa L.) seed extract containing polysaccharides on human keratinocytes and fibroblasts

To protect the body against environmental threats, cosmetics can play important antiinflammatory and anti-aging roles. Many researchers have developed cosmetic ingredients using natural plant extracts or the active compounds of such extracts. In this study, we assessed the ability of extracts from the seeds of alfalfa (Medicago sativa L.) to affect skin cells. In a keratinocyte-derived cell line (HaCaT cells), alfalfa polysaccharide extract (APE) treatment triggered cornified envelope formation and increased the gene expression levels of filaggrin and involucrin, suggesting that APE increased epidermal cell differentiation. In addition, APE dramatically increased the mRNA and protein levels of claudin1, suggesting that it enhances tight junction formation. Finally, APE exerted antiinflammatory effects in keratinocytes by decreasing the LPS-induced production of proinflammatory cytokines. In primary normal human dermal fibroblasts (NHDF), APE increased procollagen synthesis and decreased elastase activity and metalloproteinase-1 (MMP) secretion. APE also showed superoxide dismutase (SOD)-like activity in a cell-free system, resulting in antioxidant effects. Finally, we found that the polysaccharides from alfalfa seeds used in our experiments consist mainly of galactose and mannose. Based on our findings, we conclude that APE may have potent skinprotective and skin-improving effects and could be developed as an important ingredient in cosmetics and medicines.