Evaluation of Hair Growth Promoting Activity of Standardized Soybean Extract on Testosterone-Induced Alopecia

Millions of men and women suffer from alopecia, especially androgenic alopecia (AGA), which is considered the most common form of hair loss. The available treatments for hair loss include multiple approaches, with the most popular being synthetic drugs including minoxidil and finasteride, in addition to natural products. However, synthetic drugs have shown many undesirable side effects, on the contrary, the specifications of the commonly used natural drugs have not been reported in most of the previous studies, despite the high market preference for them. One of these natural drugs is soybean (Glycine max), an economically important bean that has been reported in several studies to effectively prevent hair loss in humans and is widely used in many products treating alopecia. However, no reports were traced on the specification and standardization of the used soybean extract, which may lead to unreproducible results. Thus, in this study, we investigated the effects of different concentrations; 1%, 3%, and 5% (v/v) of a specified soybean extract (SSE) in coconut oil, using a testosterone-induced model of alopecia in adult male Wistar rats in comparison with a 2% finasteride solution. Visual and microscopical evaluations of follicular diameter, length, and density were performed. The data showed that 5% of SSE exhibited the highest activity with results comparable to standard 2% finasteride for hair diameter, length, and density, which could be attributed to the extract's isoflavone content. Genistin and diadzin isoflavones were isolated from the ethyl acetate fraction of the SSE. The total extract was standardized using high-performance liquid chromatography using genistin as a marker and showed a content of 6.2 µg/mL. Accordingly, the formulated 3% and 5% SSEs (containing 0.186 and 0.31 µg/mL of genistin, respectively) could be considered as a promising natural treatment for AGA.