Topical application of standardized capsicum and rosemary extracts promotes hair growth in testosterone induced alopecia in Wistar rats: Histological and morphometric evaluation

Abstract

INTRODUCTION: Alopecia, a common condition causing hair loss, leads to decreased self-esteem worldwide. Natural extracts such as rosemary (Rosmarinus officinalis L.) and capsicum (Capsicum annuum L.), traditionally used for various medicinal purposes in Egypt, are widely utilized in treatments for androgenetic alopecia and hair care products. However, these extracts lack market standardization and clear specifications, leading to inconsistent and unpredictable effects. OBJECTIVES: This study aims to investigate the effects of standardized rosemary and capsicum extracts on testosterone-induced androgenetic alopecia in rats to ensure consistent quality and safety in marketed hair care products. MATERIALS AND METHODS: The study involved preparing standardized rosemary and capsicum extracts and developing simple, accurate, sensitive, rapid, and reproducible methods for both. The extracts were tested on adult male Wistar rats with testosterone-induced alopecia, using a 2% finasteride solution as a reference standard. Visual and microscopic evaluations were conducted to measure three hair follicle parameters: diameter, length, and density. RESULTS: This study demonstrated the potent effects of standardized rosemary and capsicum extracts on hair growth parameters over 21 days; the application of 0.075% of standardized capsicum extract significantly improved hair growth parameters, including follicle density, length, and diameter. Furthermore, standardized rosemary extracts at 3% and 5% concentrations showed significant improvements across all measured parameters, particularly in hair follicle density. CONCLUSIONS: This study highlights the potential of standardized rosemary and capsicum extracts in promoting hair growth parameters, including hair follicle density, length, and diameter. It will pave the way for more effective natural-based androgenetic alopecia treatment.