Introduction ! Hair loss is characterized by abnormal hair cycles. Three phases, anagen (growth), catagen (regres- sion) and telogen (resting) organize the hair cycle and so control the hair development [1]. These dermatologic processes frequently co-occur peri- follicular lymphocytic infiltrate-affected anagen, induction of apoptosis-regression catagen and prolonged telogen. Most of all, dystrophic hair fol- licles affected by the induction of apoptosis in the catagen phase exhibit reduced size and inconsis- tent pigmentation, resulting in a disabled state of production of hair fiber [2]. These imbalances be- tween the follicle growth and the induction of ap- optosis result in hair loss [3]. Some of the hair development promoting drugs against hair loss are capable of transiting from tel- ogen to anagen [4]. Two typical anti-hair loss agents, finasteride and minoxidil, have been re- ported to induce late anagen from early anagen [5]. Finasteride appears to inhibit type II 5α-re- ductase, thereby blocking the conversion of tes- tosterone to dihydrotestosterone and minoxidil is efficacious in transition from the early to late anagen phase of hair follicles [4,6]. However, fi- nasteride is used for androgenic alopecia male pa- tients and female patients who are past the child- bearing age [7, 8]. Minoxidil is known to cause un- expected side effects such as pruritus, dryness, scaling, local irritation and dermatitis [9]. Accord- ingly, the use of these two famous drugs is limited in spite of its efficacy on promoting hair growth [5]. Alternative treatments are required due to the high relapse rates, varying levels of efficacy and concerns about adverse effects. Formononetin (7-hydroxy-40-methoxyisofla- vone; C 16 H 12 O 4 ) is the main compound of red clo- ver plants Trifolium pratense L. (Fabaceae), which belong to herbal isoflavone [10]. The effects of red clover on the scalp hair conditions in post-meno- pausal women have been reported [11]. However, few reports investigate the effects of formonone- tin on apoptosis of hair follicle, although numer- ous studies reported that formononetin has di- verse biological effects, including hypolipidemic, anti-oxidant, anti-viral, cardioprotective, immu- nomodulatory and estrogenic activities [10, 12– 17]. In addition, a molecular mechanism of for- mononetin-promoted hair regrowth against alo- Abstract ! Formononetin is one of the main components of red clover plants and its role on hair regrowth against hair loss has not been established yet. In the present study, we assessed the potential ef- fects of formononetin on alopecia, along with im- paired hair cycles by induction of apoptosis-re- gression. Depilated C57BL/6 mice were used for monitoring the hair cycles. Formononetin (1 and 100 μM) was topically treated to the dorsal skin for 14 days. Topical formononetin treatment induced minia- turized hair follicles to recover to normal sizes. Tapering hair shaft began to grow newly, emerg- ing from the hair follicles by formononetin. In ad- dition, formononetin inhibited the activation of caspase-8 and decreased the procaspase-9 ex- pression. As a result of formononetin treatment, anti-apoptotic Bcl-2 was up-regulated, whereas pro-apoptotic Bax and p53 were down-regulated, resulting in a decrease of caspase-3 activation. Formononetin showed the obvious inhibition of apoptosis under terminal deoxynucleotidyl trans- ferase dUTP nick end labeling staining thereafter. Taken together, our findings demonstrate that formononetin exerted the hair regrowth effect on hair loss, in which the underlying mechanisms were associated with Fas/Fas L-induced caspase activation, thus inhibiting apoptosis. Topical Treatment of Hair Loss with Formononetin by Modulating Apoptosis Authors Mi Hye Kim 1 , You Yeon Choi 1 , Ji Eun Lee 1 , Kyuseok Kim 2 , Woong Mo Yang 1 Affiliations 1 College of Korean Medicine and Institute of Korean Medicine, Kyung Hee University, Seoul, Korea 2 Department of Ophthalmology, Otorhinolaryngology and Dermatology of Korean Medicine, College of Korean Medicine, Kyung Hee University, Seoul, Republic of Korea Key words l " formononetin l " hair loss l " hair cycle l " apoptosis l " caspase received Dec. 24, 2014 revised May 1, 2015 accepted July 29, 2015 Bibliography DOI http://dx.doi.org/ 10.1055/s-0035-1557897 Planta Med 2016; 82: 65–69 © Georg Thieme Verlag KG Stuttgart · New York · ISSN 0032‑0943 Correspondence Woong Mo Yang College of Korean Medicine and Institute of Korean Medicine Kyung Hee University 1 Hoegi-dong Seoul 130-701, Dongdaemun-gu Korea Phone: + 82 29 61 22 09 Fax: + 82 29 61 22 09 wmyang@khu.ac.kr Correspondence Kyuseok Kim Department of Ophthalmology, Otorhinolaryngology and Dermatology of Korean Medicine College of Korean Medicine Kyung Hee University 1 Hoegi-dong Seoul 130-701, Dongdaemun-gu Korea Phone: + 82 29 58 94 99 Fax: + 82 29 58 91 80 kmdkskim@khu.ac.kr 65 Kim MH et al. Topical Treatment of … Planta Med 2016; 82: 65–69 Original Papers Downloaded by: University Bergen. Copyrighted material.