The Use of Botanical Extracts in East Asia for Treatment of Hyperpigmentation: An Evidenced-Based Review

Cosmeceuticals, topical skin products containing bioactive ingredients purported to have medical benefits, are the fastest growing beauty industry in the world with an estimated $42.8 billion worth of sales in 2018.¹ The cosmeceutical industry is particularly robust in Asia, where skin lightening takes on cultural significance. This strive for aesthetic beauty has led to the formulation of naturally-based skin care products targeted at hyperpigmentation. Korea has been at the forefront of generating the newest and most innovative cosmeceutical products. Some of the most popular ingredients used in these cosmeceuticals include green tea, soy, orchid, licorice, rice water, ginseng, bamboo, and aloe. Since the rising popularity of Asian cosmeceuticals, there has been an increasing world-wide demand for skin care products utilizing exotic plant-based ingredients. Scientists have been conducting research studies on these plant extracts, their unique properties, and their evidence-based use in the current beauty industry. With increasing consumer use of cosmeceutical products, it is imperative that physicians understand the properties of these extracts and the scientific basis of their efficacy in order to better inform patients and ensure their safety. Few research articles have explored the effectiveness of plant-based Asian cosmeceuticals in treating hyperpigmentation, and even fewer have assessed the clinical evidence behind their efficacy. In this review, we seek to incorporate the most recent scientific literature to critically appraise in vitro studies and clinical trials investigating the natural ingredients found in Asian cosmeceuticals.

A comprehensive review of the literature on natural ingredients most frequently used in Korean cosmeceuticals to treat hyperpigmentation was conducted on PubMed (U.S. National Library of Medicine). The search terms “green tea,” “soy,” “orchid,” “licorice,” “rice water,” “ginseng,” “bamboo,” and “aloe vera” were input into the advanced search tool to identify all articles discussing hyperpigmentation or pigmentary disorders from both in vitro and in vivo studies with publications up to April 2019. Non-English language articles were excluded. A total of 50 studies were included for this study.

Studies Categorized by Active Ingredients
Aloe Vera
Aloe Vera is a popular succulent plant that has long been used for many dermatologic conditions such as eczema, burn wounds, skin infections, and acne vulgaris.² Inside the leaves of the aloe vera plant is copious amounts of gel that can be squeezed out and directly applied to the skin.³ This gel has been used for its anti-bacterial and anti-inflammatory properties as well as to decrease hyperpigmentation of the skin. Aloesin, a natural hydroxymethyl chromone compound and the active ingredient in the aloe vera plant, competitively inhibits dihydroxyphenylalanine (DOPA) oxidation and non-competitively inhibits tyrosine hydroxylase activity.⁴ Melanin is synthesized through tyrosine hydroxylase and oxidation of DOPA.⁵ Thus inhibition of these steps in melanin biosynthesis has the potential to prevent overproduction of melanin and skin hyperpigmentation. A prior