Fig. 4.

Changes in the skin redness (erythema) by hydrogel.

Change of the a* parameter - the skin redness (erythema) measured by CIE L*a*b* colour space parameters (Chroma Meter, Konica Minolta, Osaka, Japan) after topical application of methyl nicotynate, emulsions containing different concentrations of Centella asiatica extract and placebo. Data represent the mean values±standard deviation. Student's t-test: P<0.05. Where: -♦- control; -▴-- placebo; -▪-- methyl nicotynate; -•-- hydrogel with 2.5% of Centella asiatica extract; -*- hydrogel with 5% of Centella asiatica extract.