There are currently only two FDA-approved drugs for treatment of androgenetic alopecia, oral finasteride and a topical minoxidil . Finasteride, a competitive inhibitor of type II 5α-reductase, inhibits the conversion of testosterone to dihydrotestosterone and, thereby decreases androgen-dependent miniaturization of hair follicles in the scalp . However, this drug is contraindicated in fertile or pregnant women due to its potential risk of malformation of the external genitalia in male fetuses. Minoxidil, a potassium channel opener, is known to stimulate hair growth, although its mechanism of action is not yet fully understood. However, the effect of this drug is variable and temporary, and several adverse effects, such as pruritus, dermatitis, and irritation have been reported [3, 4]. Consequently, there is still an unmet need for the development of novel, ideal hair growth promoters with minimal adverse effects. Currently, numerous drugs including folk medications are being used, although evidence of their efficacy and adverse effects are unclear and still under investigation [5,6,7,8,9,10,11]. The possible mechanisms of action of the current folk medications include dermal papillae activation, enhanced blood supply in the perifollicular area, anti-inflammatory action, inhibition of 5-alpha-reductase, and nutritional support for hair follicles .
Houttuynia cordata Thunb (HC), which is widely known as Eu-Sung-Cho in Korea and China, is a perennial herbaceous plant from the Saururaceae family and is widely grown in southeast Asia (in Korea, China, Japan, Taiwan, and India) [13, 14]. For decades, the root, young shoots, leaves of HC or the whole plant have been used as a traditional folk medicine for various medicinal purposes throughout southeast Asia [15,16,17,18]. For example, in India, its leaf juice was used orally to treat cholera, dysentery, and for purification of blood . It was also used as an antidote and astringent . HC was used orally to treat various minor illnesses, such as coughs, swelling, enteritis and fever in decoction form . Topically, it was used to treat snake bites and skin disorders. In the Indo-China region, the entire plant was used orally for cooling, treating furuncle, and inducing menstruation. Similarly, in Korea and China, the leaves were traditionally used orally to treat dysentery, gonorrhea, measles, hemorrhoids, and eye trouble. It was also used to drain pus and to enhance voiding . The history of such effects originated from an oriental pharmaceutical text, Ben cao gang mu  (first published in 1593, Ming Dynasty of China), which is regarded as the most complete and comprehensive medical book ever written in the history of traditional Chinese medicine.
Subsequently, since the 1990’s, experimental evidence to support the efficacy of HC has accumulated in various biological fields. Numerous studies [13, 15] have proven that HC exhibits anti-inflammatory , anti-viral , anti-bacterial, anti-cancer , and anti-allergy  activities.
Regarding its bioactive components, phytochemical investigations on HC conducted up through 2012 reported numerous phytoconstituents of this plant. Various types of chemical constituents, such as flavonoids (quercetin, isoquercitrin, rutin), aristolactams, 5,4-dioxoaporphines, oxoaporphines, amides, indoles, ionones, polyphenol (including procyanidin B-2, catechin), benzenoids, steroids and different volatile oils, have been isolated from HC [15, 23,24,25].
Besides the above discussed biological effects, HC is traditionally used orally to treat patients with alopecia. This practice also originated from the recommendations in Ben cao gang mu . Although experimental evidence regarding its hair regeneration effect has not yet been established, HC has been popularly used as a herbal hair-promoter owing to its anecdotal efficacy in Asian countries, especially in Korea. In addition, HC is often used in combination with other two herbal medicines (Perilla frutescens Britton var. acuta (PFVA) and green tea (GT)). Therefore, this “tri-mix” herbal complex (HC, PFVA, and GT) is commercialized and is being widely used by alopetic patients in Korea.
PFVA (called as Ja-So-Yup) is a naturalized edible plant, and is distributed widely throughout the Himalayan mountains and East and Southeast Asia, especially in Korea and Japan. Traditionally, it has been orally used to treat all kinds of diseases such as cold, fever, chills, headache, stuffy nose, cough or chest discomfort. PFVA extract has been reported to contain numerous functional compounds with anti-allergenic, anti-inflammatory, anti-microbial, and anti-bacterial effects [26,27,28,29].
GT (called as Nok-Cha) is one of the most prevalent drinks in Asia. Traditionally, it has been consumed (as beverage) by East Asian people for health promotion and is known to have anti-cancer and anti-oxidant actions, primarily mediated by epigallocatechin-3-gallate (EGCG) . With respect to androgen metabolism, EGCG inhibits 5α-reductase  and represses the expression of androgen receptor genes , and thereby exhibits a potential action for the prevention or treatment of androgen-dependent disorders. Kwon et al.  reported that EGCG stimulates human hair growth via proliferative and anti-apoptotic effects on dermal papilla cells. Similarly, topical EGCG was reported to reduce testosterone-induced apoptosis of hair follicles in a mouse model.
Among various species of animals, the mouse model is most widely reported for hair growth promotion studies due to availability of large data base and specific mutants such as nude, hairless, rhino, etc. The periodic intervals of rodent hair cycles, particularly the duration of the anagen phase are much more consistent and less susceptible to iatrogenic influences. The disadvantages associated with the mouse model include a high follicle density and the fact that the rodent hair cycle progresses in a wave pattern that sweep posterior and dorsally , unlike the mosaic pattern seen in humans . The truncal pigmentation of C57/BL6 mice is entirely dependent on their follicular melanocytes. The truncal epidermis in this species lacks melanin-producing melanocytes and melanin production is strictly coupled to anagen phase of hair growth. Thus, the strict coupling of follicular melanogenesis and hair follicle cycling leads to characteristic changes in skin pigmentation during anagen development. For these reasons, pigmented C57/BL6 mice are the most commonly used strain for hair growth studies.
In this study, we aimed to evaluate the hair promoting effect of the herbal complex (a combination of HC, PFVA, and GT) using C57BL/6 mice. To the best of our knowledge, this is the first experimental study on this herbal medication for treatment of hair loss.