Piperine reduces hair oiliness by inhibiting adipogenesis of hair stem cells

Piperine, an alkaloid compound in black pepper (Piper nigrum), has beneficial bioactivities. Specifically, piperine inhibits adipogenesis in 3T3-L1 cells by suppressing the transcriptional activity of PPAR gamma. Control of hair oiliness, which is related to adipogenic regulation, is important to prevent hair loss. Excessive sebum from the sebaceous gland (SG) can cause acne, folliculitis, or irritated skin by clogging pores. To investigate the in vivo function of piperine in SG, we used mice fed a high-fat diet (HFD). The HFD increased the size and Oil Red O (ORO) staining intensity of SG, which were significantly reduced by piperine. The HFD also upregulated the expression of sebocyte-associated genes, including PPAR gamma target genes, an effect reversed by piperine. In CD34/CD49f double-positive hair follicle bulge stem cells isolated from mouse vibrissae, piperine inhibited cellular adipogenesis, likely via transcriptional repression of related genes. Furthermore, piperine reduced the thickness of subcutaneous fat. In human dermal papilla cells, piperine inhibited cellular adipogenesis, as shown by the reduction in ORO staining and the downregulation of PPAR gamma target genes. In conclusion, piperine can be used to reduce hair greasiness by suppressing adipogenesis in hair stem cells.