Oral Administration of Glycine and Leucine Dipeptides Improves Skin Hydration and Elasticity in UVB-Irradiated Hairless Mice

Abstract

Placenta is a special organ that contains many nutrients such as growth factors, minerals, and bioactive peptides. Dipeptides of glycine and leucine are major components of porcine placenta extracts (PPE) that has been used as an alternative of human placenta extracts. In this study, we investigated whether major peptides of PPE, Glycyl-L-Leucine (Gly-Leu), L-Leucyl-Glycine (Leu-Gly), and L-Leucyl-L-Leucine (Leu-Leu), affect skin hydration and elasticity in vitro and in vivo. We found that Gly-Leu and Leu-Gly dipeptides induced the expression of transglutaminase 1 in normal human epidermal keratinocytes (NHEKs) whereas Leu-Leu dipeptides did not. Treatment with Gly-Leu or Leu-Gly significantly increased hyaluronan (HA) synthesis in NHEKs and the upregulation of hyaluronan synthase 2 (HAS2) mRNA level was confirmed. In addition, elastase activity was inhibited in NHEKs treated with Gly-Leu or Leu-Gly dipeptides. Oral administration of Gly-Leu or Leu-Gly dipeptides increased skin hydration and elasticity in UVB-irradiated hairless mice. The significant upregulation of HA in UVB-irradiated hairless mice was observed in response to oral administration of Gly-Leu or Leu-Gly. These results suggest that the major dipeptides of porcine placenta, Gly-Leu and Leu-Gly, are potentially active ingredients for skin moisturization formulations.

Unsaturated fatty acid‐enriched extract from Hippophae rhamnoides seed reduces skin dryness through up‐regulating aquaporins 3 and hyaluronan synthetases 2 expressions

“…According to reports, HAS2 can synthesize HA. It has been previously reported that UV exposure induced loss of HA and inhibition of HAS in skin 36 . It has been suggested that HA was involved in the natural responses of epidermal in wound‐healed and barrier recovery in AD, including proliferation and migration of keratinocyte 37 .…”

“…It has been previously reported that UV exposure induced loss of HA and inhibition of HAS in skin. 36 It has been suggested that HA was involved in the natural responses of epidermal in wound-healed and barrier recovery in AD, including proliferation and migration of keratinocyte. 37 It has been shown that HA bound to its best-characterized cell surface receptor, CD44, induced LB (lamellar body) formation and secretion, and enhanced expressions of keratinocyte differentiation markers including K10, profilaggrin, which was very important to skin barrier repair and maintains skin hydration.…”

Effect of Porcine Placenta Extract Supplement on Skin Condition in Healthy Adult Women: A Randomized, Double-Blind Placebo-Controlled Study

“…Several previous studies reported that dermal fibroblasts exist in placenta extract [ 11 , 12 ], whereas other investigations demonstrated that dermal fibroblasts enable the synthesis of collagen, elastic fibers, and dermal hyaluronic acid [ 9 , 10 ]. Although the internal mechanism of oral supplementation with porcine placenta has been unclear, a previous study reported that major porcine placenta peptides in a living organism: Glycyl-L-Leucine (Gly-Leu), L-Leucyl-Glycine (Leu-Gly), and L-Leucyl-L-Leucine (Leu-Leu), affect skin hydration and elasticity in in vitro and in vivo studies [ 42 ]. Our findings are consistent with those of previous investigations that explain the placenta extract effects with several potential mechanisms.…”

Skin Hydration Effects of Scale‐Up Fermented Cyclopia intermedia against Ultraviolet B‐Induced Damage in Keratinocyte Cells and Hairless Mice

“…Skin aging is also associated with skin water loss, the main factor being hyaluronic acid (HA), an extracellular matrix molecule [16]. Several factors control skin moisture and elasticity, including HA and elastic fibers, which regulate skin tissue elasticity and resilience [17]. Enzymes such as HA synthases (Has) synthesize HA, and Has2 expression is differentially upregulated by TGF-β1 in the dermis and epidermis [18].…”