P#47  The inhibitory effect of Houttuynia cordata Thunb extract on leg hair growth

Akihiro Ishino, Amane Tatsuta, Tomoko Yokoyama and Takanari Tsuda. Shiseido Research Center, Yokohama, Japan

While unwanted body hair can be an embarrassing and annoying problem for women, little has been known about body hair physiology. The purpose of this study was to define the basic growth parameter of leg hair and to find out inhibitors of leg hair growth. Nine female subjects (21 to 31 years old) were recruited and shaved their leg hair. After 7 to 9 days, the images of central part of the lateral side of the leg was recorded by video microscope with a glass cover attached x 25 magnification lens. The length of hair were measured by using an image analysis software program applied to the video microscope images. The growth rate was calculated by dividing the length of time. Over 0.05 mm/day growing hair was classified in anagen hair. The mean growth rate of anagen leg hair was 0.174 mm/day and there was no significant difference between both legs. To find out ingredient for inhibition of hair growth, we observed the proliferation of hair follicle keratinocyte by various plant extracts. Human outer root sheath (hORS) cells were plated at 20000 cells/well in type I collagen coated 24 well plate. On the next day the diluted plant extract were added and the number of cell was estimated by Alamar BlueTM assay on 3 days after plating. The ethanol extract of the dried Houttuynia cordata Thunb (HCT) exhibited inhibitory effect against hORS cell growth. HCT is extensively used as the traditional herb for diuretic and treatment of wounds, skin diseases in Japan. To investigate the effect of HCT extract on the growth of women unwanted hair, two test lotions, a lotion containing HCT extract and placebo lotion, were distributed to eight subjects. All subjects gave their Informed Consent. The test lotions were applied twice daily to the respective legs for 3 month. After 3 month, the mean growth rate of anagen leg hair was lower for the HCT treatment compared to the placebo treatment. These data suggested that the HCT extract had a inhibitory effect on leg hair growth.