Biological activities of the legume crops Melilotus officinalis and Lespedeza capitata for skin care and pharmaceutical applications

The search for natural principles is attracting much interest in the field of skin care. Fabaceae are major agricultural crops and potential sources of bioactive compounds with possible applications in human health and skin care. This study concerns the biological activities of the legume crops Melilotus officinalis (L.) Pall. and Lespedeza capitata Michx. for their potential use in skin care applications. The effects of plant ethanolic extracts at doses ranging from 0.25 to 50 μg/mL (from 1 to 5000 μg/mL in cell viability assays) were evaluated using in vitro tests on HaCaT human keratinocytes, 46BR.1N fibroblasts, and adipocyte cell cultures, and on matrix-degrading enzymes. MTT assay revealed weak effects on cell viability (IC₅₀ > 1000 μg/mL) and significant increase of fibroblast growth rate with both extracts. Similar induction of cell motility by the two extracts was observed on keratinocytes, while on fibroblasts M. officinalis induced a stronger effect with respect to L. capitata. Cell-free enzymatic assays showed stronger collagenase inhibition by L. capitata, while an ELISA assay revealed more efficient stimulation of fibroblast collagen production by M. officinalis. Oil-Red-O adipocyte staining showed more pronounced lipolytic effect of M. officinalis with respect to L. capitata. Both extracts showed the ability of stimulating skin cells in order to promote tissue regeneration, prevent skin aging, and reduce fat deposition. In most cases, different patterns of activation/inhibition were observed. Data indicate that these legume crops could be profitably exploited in skin care applications, possibly in combined formulations for the development of antiaging and anticellulite products.