The Potential of Plant Phenolics in Prevention and Therapy of Skin Disorders

Abstract

Phenolic compounds constitute a group of secondary metabolites which have important functions in plants. Besides the beneficial effects on the plant host, phenolic metabolites (polyphenols) exhibit a series of biological properties that influence the human in a health-promoting manner. Evidence suggests that people can benefit from plant phenolics obtained either by the diet or through skin application, because they can alleviate symptoms and inhibit the development of various skin disorders. Due to their natural origin and low toxicity, phenolic compounds are a promising tool in eliminating the causes and effects of skin aging, skin diseases, and skin damage, including wounds and burns. Polyphenols also act protectively and help prevent or attenuate the progression of certain skin disorders, both embarrassing minor problems (e.g., wrinkles, acne) or serious, potentially life-threatening diseases such as cancer. This paper reviews the latest reports on the potential therapy of skin disorders through treatment with phenolic compounds, considering mostly a single specific compound or a combination of compounds in a plant extract.

Keywords: anti-aging properties; anti-carcinogenic; anti-inflammatory; antimicrobial; antioxidant; phenolic compounds; skin diseases; wound healing.

Figure 1

The classification of phenolic compounds.

Figure 2

The examples of molecular structures of the most common phenolic compounds.

Figure 3

The scheme of factors involved in the formation of free radicals and a cellular response to reactive oxygen species (ROS). The red arrow and the text in red emphasize the importance of phenolic compounds, other antioxidants and the relationship between them. The sun signifies protection of other antioxidants by phenolic compounds.

Figure 4

The scheme presents the cross-section of the skin structure and the specific influence phenolic compounds (delivered in the cosmetic formulation form) on dermal tissue components. Black arrows indicate the particular component of skin tissue, according to which are listed the main classes of phenolic, effective in prevention or treatment signs of skin-aging. The yellow arrow indicates the direction and the depth of the cosmetic formulation permeability through the skin. The various layers of the skin structure are indicated on the left. The scheme is based on data described in the review.

Figure 5

The factors and phenolic compounds involved in the maintenance of the proper skin structure through the regulation of matrix metalloproteinases (MMPs). The white cross in the red circle and the red signs in the letter “T” shape indicate the inhibition of the MMPs activity.

Figure 6

The involvement of the tyrosinase in the reaction of melanin synthesis and the inhibition of melanogenesis by the substrate analog inhibitor, i.e., resveratrol. The black arrows indicate the direction of the reaction, the dash line indicates the involvement of the enzyme tyrosinase and the sign in the letter “T” shape indicates the inhibition of the tyrosinase by resveratrol.

Figure 7

Anticancer properties of curcumin. The green fields indicate the properties of the curcumin, while violet fields indicate the particular examples of the of the curcumin action.

Figure 8

The anticancer properties of phenolic compounds.

Figure 9

Anti-allergic properties of phenolic compounds.

Figure 10

The process of wound healing.

Figure 11

The effect of phenolic compounds derived from the flax dressing on the wound healing. Left picture presents the wound before treatment and the right presents the wound after the 12 weeks of treatment (based on the unpublished data from research of Szopa et al.).