INTRODUCTION

With over 2000 species identified Astragalus plants are part of the Leguminosae family, grow well in temperate environments, and are commonly used in Asian traditional medicine for a wide variety of ailments, including dermatological disorders [1–5].

While initially used for livestock and human consumption [6], Astragalus has been used in Chinese traditional medicine in treating diabetes, hypertension, and cancers, including leukemia and uterine cancer, as well as used for antiperspirant, antimicrobial, and tonic properties [4–7], Astragalus extracts are mainly made of saponins, terpenoids, flavonoids, and polysaccharides, which are believed to serve as active ingredients with antioxidant properties that can impart expedited healing [8]. Decreased aging is also found with astragaloside administration, a derivative of Astragalus extract, where the mice treated had brain function and blood serum composition more similar to younger mouse populations [9]. Traditional and modern uses of Astragalus include enhancing skin health and preventing and treating dermatological diseases. Traditional Chinese medicine uses astragalus as a Qi enhancer, known as life energy believed to travel through the human body, thus promoting the immune system, increasing vitality and energy, and preserving skin health [10–17]. Extract from Astragalus gombiformis has been shown to absorb UV radiation at an SPF of around 37.78, prevent inflammation at a percentage of 75.38%, and have a cytotoxic effect against Artemia nauplii but not against human erythrocytes [18]. This species of Astragalus has also been found to have at least 17 phenolic compounds that have strong antioxidant and anti-inflammatory properties [18]. Astragalus membranaceus was found to reduce DNA damage due to UVA exposure [18]. Topical astragalus, specifically Radix astragali, both fermented and non-fermented, have been shown to stimulate keratinocyte and fibroblast growth and hyaluronic production, and have low toxicity in vitro tests [19].

There are already products on the market that contain a large concentration of Astragalus derivatives. Listed on INCI Decoder, there are over 90 topical skin creams, toners, and essences with Astragalus currently on the market [20]. Some of the marketing claims advertising these products include “boosting energy,” treating skin problems associated with “diabetes” and “night sweats,” and resolving “acne,” “psoriasis,” “rosacea,” “hyperpigmentation,” and “dermatitis” [21–23]. Companies claim that it is useful in “deep moisture” due to “excellent absorption of the production” and it improves “skin elasticity,” “inflammation,” and “collagen production” [21–23].

Fortune Business Insights projects an economic increase in the skincare market, worth around 133.90 billion USD in 2018 to 200.25 billion USD by 2026, with a substantial percentage from the Asia Pacific. This sets the perfect environment for a large expansion of Asian skincare products that include Astragalus [24], thus potentially false marketing regarding the efficacy of this ingredient in dermatological diseases. Because of the long history of Astragalus use in medicine, including skincare, as well as the current integration of Astragalus in the cosmetic industry, consolidation of the available literature on the efficacy of topical Astragalus is vital in critically addressing current marketing claims and increasing consumer and manufacturer awareness of its uses.

As of this paper, no study has consolidated its benefits in all dermatological diseases through in vivo topical application. In this paper, we are performing a systematic review of the current publications regarding the topical effects of Astragalus derivatives on cosmetic properties of the skin, including the treatment of dermatologic diseases. We addressed its beneficial and harmful effects on skin health, determined the limitations of each study found, and consolidated this knowledge to disprove misleading marketing claims.

METHODS

Six possible search terms were created through the use of boolean operators, including the following: Astragalus topical skin*, Astragalus topical derm*, Astragalus topical cosmetic*, Astragalus topical hair*, Astragalus topical nail*, Astragalus topical beaut*. A C#.NET console application ran the search terms through PubMed to query the resulting links through an HTTP request. All subsequent literature was collected in February, 2022 and there were 27 publications gathered. Duplicates were removed and 18 publications were unique. Using our inclusion and exclusion criteria, the abstracts were initially reviewed to determine the papers’ relevance, and irrelevant articles were removed. Our inclusion criteria included trials measuring the topical use of Astragalus derivatives on the skin in vivo in treating dermatological diseases, tested on animals and humans, and published at any point in time. Exclusion criteria include trials that do not have a vehicle or control; trials that focused on in vitro and ex vivo results; trials that only had histological parameters; reviews, commentaries, editorials, or any publications that did not present any original data; and articles not written in English. The resultant sum included 11 papers that fit the exclusion and inclusion criteria given (Fig. 1).

Figure 1: PRISMA Model of the performed methods, updated as of Feb 2022.

These publications were read entirely for their content, leading to a final 11 papers that fulfilled both the inclusion and exclusion criteria. Different data points were collected from each paper, and to reduce the risk of bias, different data points were collected by two reviewers, independently. The subsequent information was consolidated, and limitations and potential future research were assessed, discussed, and recorded. Data categories that were not included in each study were listed as “Not Available (N/A)” (Fig. 1).

RESULTS

Conglomerate Publications Information

The average sample size taken was 23.6. The average length of the studies was 12.5 days. Of the studies, mouse test subjects were most frequently utilized (77.8%), followed by rats (11.1%), and guinea pigs (11.1%) (Table 1).

Table 1: Summary of Publication Data.

DISCUSSION

Topical application of Astragalus in animal studies has shown alleviation of various skin conditions, but none have investigated its effects in humans.

Most studies suggest that the beneficial effects of Astragalus are due to immunomodulation [29,30,33,36,37]. One study investigated antimicrobial properties but was unable to identify a mechanism for the antifungal action of Astragalus verus olivier [35]. Few studies investigate side effects or efficacy compared to accepted pharmacologic treatment. One study comparing Astragalus to other treatments found that the overall efficacy of Astragalus extracts was lower than standard-of-care treatments [35]. However, a different study by Han and colleagues found that the effects of Astragalus were superior to those of EGF in wound healing [32]. Future studies comparing Astragalus to approved, standard-of-care medications could be relevant to clinical practice, if tested on humans. As an example, comparing astragaloside IV to FDA approved drugs for hair loss, such as finasteride and minoxidil, may demonstrate interesting results.

In wound healing, upregulation of angiogenic factors may be one mechanism for Astragaloside IV. Astragalus gummifer’s wound-healing abilities may be related to structural similarity to chitosan, another arabinogalactan-containing polysaccharide biopolymer that has been demonstrated to accelerate wound closure [38,39]. There are current materials on the market, such as HyaloFill, based on the extracellular matrix and polysaccharide structures intended as skin substitutes [40]. In the setting of MOHS microscopic surgery, these materials have been shown to clinically augment wound healing [41]. However, no human trials on Astragalus and wound healing have been conducted and animal trials are potentially confounded by variations in animal behavior that may diminish wound healing activity. Applying separate wounds to the same animal may also reduce this limitation [34]. While this data shows some promise in the topical use of Astragalus as a dermatologically effective ingredient for treatment, a major limitation is that none of the current literature measures its effects on human subjects.

Another limitation of many of the reviewed studies is that human skin conditions were studied using animal models with chemically or other artificially induced skin conditions, rather than on animals that had naturally developed these skin conditions [29,30]. Due to this limitation, the effects of Astragalus on humans with organically developed skin conditions may differ from what was observed in the above studies

Even with these limitations, further publications support that Astragalus derivatives are a promising ingredient to incorporate as an adjunct to currently established treatments for dermatological diseases. It is appropriate to use commercially as a cosmetically beneficial ingredient and may be implemented in the future for clinical use. While there are major limitations to some of the studies that were discussed, preliminary data in vitro and in vivo supports the proposed mechanism in skin diseases, and show that it does not induce skin irritation, decrease dermatological symptoms, promote wound healing, and may treat alopecia.

CONCLUSIONS

With its long history in medical use throughout Asia, Astragalus is a species of plant that has become more widely used in modern medicine and cosmetics. Its growing popularity in commercial use begs the question of its efficacy on dermatological conditions with topical application. We found that Astragalus has preliminary animal research supporting its treatment of dermatitis, alopecia, dermatophytes, and wound healing, and has the potential to be more effective than established treatments. Additional experimentation is still needed to measure its effects long-term, against current treatments, and in human trials, however, its current use in cosmetics, skincare, and clinics can be beneficial to consumers to enhance skin health and treat skin diseases.

REFERENCES

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