Evaluation of moisturizing and irritation potential of sacha inchi oil.

Abstract

The moisturizing and irritation effects of sacha inchi oil were evaluated. The moisturizing effect on the skin was clinically assessed using a regression study design. Sacha inchi oil or olive oil (benchmark) was applied on the left or right lower leg of the subjects for 14days followed by application discontinuation for 2days. The TEWL, skin moisture content and dryness appearance were observed. The fatty acid composition and characteristics of cold-pressed sacha inchi seed oil were determined. Skin tissues cultured ex vivo were used to assess primary irritation induced by the oil by examining keratin 1 expression and TNF-α and IL-1α release from the oil-applied tissues. The sacha inchi oil contained 42.3% linolenic acid and 39.5% linoleic acid. This oil's saponification, iodine, acid and peroxide values were 168.58±1.55mg KOH/g, 203.00±0.04g I2 /100g, 1.68±0.03mg KOH/g, and 1.95±0.26mEq peroxide/kg, respectively. Compared with nontreated skin tissues, induced secretion of TNF-α and IL-1α and disruption of keratin 1 integrity in the stratum corneum layer were not found in the sacha inchi oil-treated tissues. In a clinical study with 13 volunteers, the improvement in moisture content and skin dryness appearance at the sacha inchi oil-applied site was comparable with that observed at the olive oil-applied site. The sacha inchi oil was mild to the skin and benefited dry skin.