Bioassay of Crude Drugs for Hair Growth Promoting Activity in Mice by a New Simple Method

In 1980, Tanaka, Saito, and Tabata conducted a study to evaluate the hair growth promoting activity of four commercial hair tonics and 33 crude drugs using a new simple method they developed. They applied these substances to depilated areas on 5-week-old mice and measured the hair growth over time. The study found that alcoholic extracts from the bark of Cinchona succirubra, the root bark of Dictamnus dasycarpus, the seeds of Brassica juncea, and the roots of Sophora flavescens were effective in promoting hair growth. One of the commercial hair tonics also showed significant hair growth promotion after 6 days. The researchers concluded that certain crude drugs, particularly the Cinchona extract, have the potential to promote hair growth and prolong the hair growth period. They recommended their softening method for bioassay due to its simplicity and effectiveness.