**1.4 Hair loss**

Research has shown that in hair loss, the percentage of telogen follicles is increased, while the percentage of anagen and catagen follicles is reduced. A healthy individual loses approximately 100–150 hairs per day [6]. Cell-signaling pathways in hair follicular cells resulting in the induction of apoptosis, changes in usual pattern of hair cycling, inducing the hair follicle to turn into regression or resting phase and thinning or fracture of the hair shaft leads to progressive hair loss and alopecia [7].

Hair loss is a universal problem for numerous people in the world, is a disorder in which the hair falls out from skin areas such as scalp, the body and face. Multiples factors contribute to hair loss including genetics, hormones, nutritional status, and environmental exposure (exposure to radiations, environmental toxicants…), medications and nutrition.

Androgenic alopecia can be suffered by women and men and the androgens hormones are the most important of the factors that cause the hair lost patron characterized by a miniaturized of the hair follicles that leads to hair lost in the frontal to parietal area.

Other forms of hair loss are for example caused by immunogenic hair loss, like alopecia areata, this is characterized by a spot of hair lost all around the scalp. The approved therapies such as finasteride and minoxidil, are the traditional medication used for this hair lost diseases, a few others are in progress, like a wide variety of diverse phytochemicals, including those present in ginseng, the ginsenosides which have demonstrated hair growth-promoting effects in a large number of preclinical studies [7].

Androgenic baldness (androgenic alopecia) and circular/spot baldness (alopecia areata) are the most common forms of hair loss. The first is characterized by high sensitivity of the hair follicles to DH, while the second is induced by an autoimmune reaction [8, 9]. Hair also possesses its own immune system, the failure of which can lead to spot baldness (alopecia areata).

Alopecia is extended all round the world, reaching nowadays approximately to 10 million patients suffering from alopecia. Considering the pathological background of alopecia and its impact on an individual's health and social value, there is now a growing interest in the development of novel therapeutics for its medical management [7].
