Arnica Montana Flower Extract Reduces Appearance of Aging

The loss of adipose tissue volume plays an important role in the appearance of skin. The decline in volume is attributed to aging and UV exposure. Adipocytes are located in the lowest layer of skin structure and play a role in energy storage by storing fat as triglycerides. Generally, there is a bias that adipose tissue is not good for beauty, because the term “adipose tissue” is linked to obesity. However, adipose tissue has important functions in physiology and appearance.

Adipose tissue stimulates other tissues by secreting various adipokines such as adiponectin and leptin, which are known as longevity hormones. For example, adiponectin increases hyaluronic acid (HA) secretion from fibroblasts of skin tissue, improving skin moisture. Adipose tissue also responds to cytokines and growth factors derived from other tissues and then controls various physiological functions: energy homeostasis, insulin sensitivity, hormone secretion and inflammation. In addition to these physiological functions, adipose tissue has a role in improving appearance. Local fat accumulation improves wrinkles and creates plumpness. Preadipocytes in the scalp act on hair stem cells to promote hair growth.

It has been reported that both replication and differentiation rates of human subcutaneous preadipocytes are significantly reduced in older subjects compared to healthy young ones. A decline in adipose tissue decreases skin elasticity and leads to wrinkle/bump formation with dark impression. To regain adipose tissue volume lost with aging and UV exposure, fat injection is done in face (eye bags, cheeks, forehead), lips and breasts. However, fat injection is invasive and surgical, making it not readily available to many consumers. If topical skin agents such as cosmetics could be used to boost skin volume, even if the effect might be more moderate compared with fat injection, it would not only be non-invasive and painless, it would allow for self-care anywhere.

Activate Preadipocytes

The strategy to boost volume via topical skin agents is through growth and differentiation of subcutaneous preadipocytes. Adipose tissue consists of adipose stem cells, preadipocytes and mature adipocytes. Preadipocytes become plumped mature adipocytes by accumulation of lipid droplet in the cells. This strategy is akin to increasing the number of shrunk balloons (first step) and inflating them (second step). Although natural extracts that accelerate growth of preadipocytes or differentiation of preadipocytes to mature adipocytes have been reported, to our knowledge, natural extracts possessing both functions have not been reported.

To investigate plant extracts acting on preadipocytes, screening was performed in hundreds of extracts of natural plants by measuring the degrees of preadipocytes proliferation and differentiation (lipid droplets formation) into adipocytes. Only Arnica (Arnica montana L.) flower extract (AFE) was found to be a suitable candidate that accelerated both growth and differentiation of preadipocytes. Arnica montana L. (Asteraceae family) is a strong and beautiful flower growing in harsh environments such as high mountainous areas in Europe. It has been known that AFE has medicinal effects such as anti-inflammatory and blood circulation promotion. Since Arnica montana L. flower belongs to Asteraceae family, the activities were further compared to those of other 14 members. AFE had potent activities on both growth and differentiation of human subcutaneous preadipocytes than other members.

AFE Accelerates Growth

As shown in Fig-1A and B, AFE accelerated growth rate by 20% and differentiation rate by 25% at the concentration of 0.1%. Interestingly, AFE did not affect growth of human dermal fibroblasts, meaning AFE selectively acts on preadipocytes.



It has been known that mature adipocytes secrete a variety of adipokines. Among them, adiponectin is a longevity hormone and is a marker of mature adipocytes. As shown in Fig-1C, adipocytes differentiated in the presence of 0.1% AFE produced adiponectin 27% higher than adipocytes differentiated in the absence of AFE. These results indicate that the adipocytes differentiated in the presence of AFE are good adipocytes.

Human subcutaneous preadipocytes were 3D-cultured and differentiated in the presence of AFE. As shown in Fig-1D, the size change speed was significantly faster in the presence of 0.1% AFE. The spheroids of Day 8 were collected, and the number of cells and the amount of lipid droplets contained in the spheroids were evaluated by tissue section. The amount of accumulated lipid droplets per cell was 1.8-fold greater when differentiation in the presence of AFE (n = 20, p < 0.001 by Student’s t-test). The calculated volume from surface area value indicated that AFE increases volume ratio 2.5-fold.

AFE Increases Volume

In human clinical test, the increased volume effects of AFE on lips, face and breasts were evaluated. The three times daily applications of the lip gel with 1% AFE on the lips, by a panel of 12 Japanese men and women aged between 41 and 62 years (mean age: 49 years), led to a significant increase in the relative volume of the lips after four weeks of application of the lip gel. As shown in Fig-2A, +0.18 mL on average on the whole panel compared to baseline. Two-thirds (67%) of the panelists noted an improvement in the parameter at four weeks. As a result of the volume increase, a significant improvement in both the relative wrinkles and brightness of the lower lip were confirmed.



Twice a day, a panel of 12 Japanese men and women  (between 41 and 62 years old, mean age: 49 years) applied a face gel with 1% AFE. There was a significant increase in the relative volume of the face with AFE compared with placebo  (Fig-2B). The increased volume was calculated as +0.71 mL on average on the whole panel compared to baseline. Nearly all (92%) of the panelists note an improvement in the parameter, after four weeks. Increased volume led to a significant improvement in the relative elasticity of eye bags. Smile lines improved and cheeks brighted.

A panel of 22 Caucasian women (29 to 55 years  years old with a mean age of 43 years), applied an emulsion with 1% AFE on the breasts. Panelists had displayed a loss of skin firmness and had A or B bra cup size. Sixteen of the 22 subjects showed an improvement in the relative bust volume, with +0.3% on average on the whole panel, after four weeks of study in comparison with baseline. In some volunteers, the top line of the breasts became higher (Fig. 3).



To conclude, AFE significantly increases the number and volume of preadipocytes in vitro. Since adipose tissue is located in the lowest layer of skin structure, skin permeability of AFE is an important factor to deliver the active components to adipose tissue. The effectiveness was so strong that AFE showed phenotype at concentration of 0.01% to 0.1% in vitro. If even a small amount of AFE reaches adipose tissue, it may exert effects in vivo. Actually, gels containing 1% AFE successfully enhanced the volume of lips, face and breasts, which improves elasticity, smoothness and brightness of skin, in human clinical test. AFE would be a very ideal ingredient for brightness and, of course, plumped skin. 

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