Kiwi berry leaves extract reveals “excellent cosmetic ingredient” for skin and eye applications, study shows

01 Jun 2022 --- A study on the “cosmetic ingredient,” Actinidia arguta (kiwi berry) hydroalcoholic leaves extract, was for the “first time” tested for its anti-aging skin effects and safety in-vitro and ex-vivo following the 2030 United Nations Agenda goals. The enzymes in the extract, elastase and hyaluronidase, were also found to be inhibited. 

“Kiwiberry is rich in phytochemicals that contribute to its skin anti-aging effects, namely polyphenols, where it could be found flavan-3-ols, representing the major class presented, flavonols, phenolic acids and flavonoids,” Francisca Rodrigues, Ph.D. at Instituto Superior de Engenharia do Porto, tells PersonalCareInsights. 

“The anti-inflammatory activity of the extracts has also been demonstrated, allowing for a possible anti-acne application. We are now developing and validating new anti-aging products soon to be tested in-vivo.”

The results of testing hydroalcoholic kiwi berry leaf extract were “an excellent cosmetic ingredient, not irritant to skin application.” 

Environmentally sustainable extraction
Over the last decade, the demand for new environmentally sustainable active ingredients has been trending, which the Portugal-based researchers note is not being “solved” by the industry. They believe that regulatory aspects are necessary to establish guidelines to assess the safety and efficacy of new cosmetic ingredients before introducing them into the market. 

“A new trend in the cosmetic industry is using raw materials considering sustainable principles, not only regarding samples but also extraction techniques,” adds Rodrigues. 

“My research team has been compromised during the last decade in several research projects related to the search of bioactive compounds from plants and food by-products for skin application (such as kiwi berry, chestnut, coffee, Salicornia, almonds, or even olive), as well as their characterization, safety evaluation and the development of new cosmeceutical ingredients and formulations.”Hydroalcoholic kiwi berry leaves extract had an elastase and hyaluronidase inhibition. 

“Our aim is to create a sustainable concept inside the beauty industry, demonstrating the advantages of recycling and valorizing products without added value,” states Rodrigues.

Rich compounds for anti-aging
Rodrigues explains that it is also possible to find vitamins A, C, E, B6 and B8, along with pigments such as β-carotene, lutein, anthocyanins and chlorophylls. 

Additionally, sugars like fructose, glucose and mainly sucrose are found. Organic acids (primarily citric acid), minerals such as potassium, calcium, sodium, magnesium or iron and amino acids like glutamic acid and aspartic acid are also available.

Lastly, fat acids such as palmitic acid as the primary saturated acid and α–linoleic acid as the main unsaturated acid can be found. 

“These compounds, particularly phenolics, can scavenge reactive oxygen and nitrogen species, responsible for the oxidative stress phenomenon. This phenomenon is the basis of the wrinkle formation,” says Rodrigues. 

Phenolic compounds inhibit elastase and hyaluronidase
Hydroalcoholic kiwi berry leaves extract of 1 mg/mL concentrate has “a non-irritating profile for skin and eye applications” through 3D in-vitro models. “The ex-vivo skin permeation showed a good permeability of 1-feruloyl quinic acid, 5-caffeoylquinic acid and rutin,” say the researchers. 

In-vitro tests showed that hydroalcoholic kiwi berry leaves extract did not decrease the fibroblasts and keratinocytes viability. 

The hydroalcoholic kiwi berry leaves extract had an elastase inhibition of 65.62 ± 2.09% for the concentration of 1 mg/mL. The researchers explain that the elastase enzyme accelerates the skin aging process. 

Additionally, their previous study found that the extract contained large amounts of phenolic acids and flavonoids, such as derivatives of flavan-3-ol and flavonols – which can inhibit elastase.

Moreover, the scientists reported hyaluronidase inhibition at 54.64 ± 4.17%. The researchers explain that the hyaluronidase enzyme is responsible for skin hyaluronic acid degradation.

“Similarly to the anti-elastase activity, the anti-hyaluronidase capacity is dependent on the biological properties provided by the phenolic compounds,” they flag. Kiwiberry is rich in phytochemicals that contribute to its skin anti-aging effects. 

Skin models and human testing 
In the last years, the researchers have validated new cosmeceutical extracts by in-vitro, ex-vivo and in-vivo assays following European Regulation number 1223/2009, shares Rodrigues.

3D models of skin (EpiSkin) and an ocular (SkinEthic HCE) were used to test the irritant potential.

“The IL-1α released for the skin and ocular models were 0 pg/mL and 35.60 ± 2.61 pg/mL, being the extract classified as non-irritant for both models,” say the scientists. In-vivo studies in 10 human volunteers confirmed the absence of allergic or irritative reactions.

Circular economy and ingredient regulations
Rodrigues and her team have collaborated with regulatory and cosmetic industries to ensure the final validation and use in anti-aging formulations. 

Guidelines were provided by the Scientific Committee on Consumer Safety of the EU to test the safety and evaluation of the extract. 

“Besides that, considering the [United Nation] Agenda 2030 principles, our research has been contributing to tackle the sustainable development goal 12 by promoting sustainable consumption and circular economy through the valorization of fruit by-products solution using innovative extraction techniques to reduce food waste and minimize the environmental footprint of these materials.” 

Portugal being one of the significant European fruit producers and within the top ten world producers of kiwi berry, inspired Rodrigues and her team to use fruits for new cosmeceutical applications. 

“Kiwiberry is an excellent source of polyphenols but highly susceptible to loss. Damaged fruits and fruits without caliber to be commercialized are considered by-products. Besides, seeds and pomace are discarded after processing kiwi berry into longer shelf life food products, while leaves are removed to increase the solar exposure during production,” explains Rodrigues.

In her previous study, researchers developed eco-friendly techniques to extract the bioactives from leaves, pomace and damaged fruits of kiwi berry for skin benefits. 

By Venya Patel