Abstract
Hair graying occurs worldwide, and it has a high impact on an individual's self-esteem. Hair graying is a melanogenesis disorder attributed to many factors, including age, oxidative stress, psychological stress, and malnutrition. Though there are effective p-phenylenediamine based hair dyes, they often cause allergy and systematic toxicity. Plants are a popular traditional remedy for the management of hair disorders. Due to their high chemical diversity, phytoproducts offer great promises to develop an effective and safe product to manage hair graying and melanogenesis disorders. The present article aims to review plants with traditional uses and bio-activity against hair graying. An extensive literature search was conducted on PubMed, Science Direct, and Google Scholar databases using many combinations of the following keywords: plants used to treat gray hair, natural products, hair graying, melanogenesis, pigmentation, and tyrosinase activity. This review documented about sixty-one plants, including a summary of 47 plants frequently used in traditional medicine and a brief review of fourteen plants showing promising activity against hair graying. The active constituents and the mechanisms by which active constituents exert anti-hair graying effects were reviewed.