Future Cosmeceuticals of Dermatologic Importance

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Chapter 32 Future Cosmeceuticals of Dermatologic Importance

Neil S. Sadick

INTRODUCTION

As the aging population grows and the choice of cosmeceuticals becomes ever more discrete, cosmetic composition is essential in the antiaging field. But it is vital that the force behind innovative skin care lines is both clinical and scientific. This new generation of cosmeceuticals focuses on cell protection from both environmental and genetic forces.

ANTIOXIDANTS

Our skin is continuously exposed to oxidative stress leading to accelerated aging by damaging DNA, lipids, and proteins. Various endogenous antioxidant systems are designed to protect us from these oxidative stresses. Oxidative stress results from many sources including genetics, environmental factors, and ultraviolet (UV) radiation. The action mechanism of antioxidants in induction is such that they prevent free radicals from forming chain reactions that have the capability of damaging cells during oxidation of other molecules. Antioxidants are comprised of various molecules such as alpha lipoic acid (ALA), coenzyme Q-10, polyphenols, idebenone, kinetin, and vitamins A, B, C, and E. Antioxidants are widely used as treatments in many human diseases and have now become a vital source in cosmeceuticals because of their strong photoprotective effects, thereby resulting in reduction of erythema, sunburn cell formation, DNA changes, and carcinogenesis Fig. 32.1.

image

Fig. 32.1 Free radical theory of aging

POLYPHENOLS

Polyphenols are groups of chemical substances with diverse and complex chemical structures that are found in plants. Flavonoids are one subgroup of polyphenols, including grape seed extract and soy isoflavones. Flavonoids are found in a large variety of foods, thus a diet high in phytochemicals along with topical application may protect the skin from endogenous and exogenous stress. It is believed that polyphenols not only protect cells from further damage but also promote cell revival. A study was conducted to measure the extent of effectiveness of polyphenols on UV skin damage. Epigallocatechin-3-gallate (EGCG), one of the main components of green tea, has been reported to have anticarcinogenic effects on the skin when exposed to UV radiation. In one study mice were exposed to UVB twice a week for 20 weeks (radiation dose between 280 and 375 nm). Some of the mice were then treated topically with EGCG (3.0 mg, 6.5 μmol) five days a week for 18 weeks. Some of the mice were treated with caffeine. Tumor formation was measured. The control group, which was exposed to UVB but was not treated with anything, developed an average of 4.5 tumors per mouse after 12 weeks. The caffeine-treated group developed 1.3 tumors per mouse and the EGCG-treated group developed 0.8 tumors per mouse. After 18 weeks, the control group developed 6.9 tumors while the caffeine and EGCG groups developed 3.6 and 2.5 tumors respectively.

GENISTEIN

Genistein is a soybean isoflavone that was first isolated from soy beans in 1931. It is a potent antioxidant with specific inhibitors of protein tyrosine, kinase, and phytoestrogens, increasing the thickness of the skin through an estrogenic effect. It has been found that it exhibits properties preventing the hemolysis of red blood cells by dialuric acid or H2O2 and inhibiting microsomal lipid peroxidation induced by Fe2+-ADP complex and NAPDH. It is the most potent inhibitor of P450-mediated activation of benzo[a]pyrene among all isoflavones.

Multiple studies over the past decade have given support to the belief that these natural ingredients have preventive and therapeutic effects on breast and prostate cancers, osteoporosis, cardiovascular diseases (in humans and animals), and postmenopausal syndrome. Genistein has significant effects in terms of inhibition of chemical carcinogenesis, UV-induced skin carcinogenesis and photo-damage in both humans and mice.

Although numerous in vitro studies have shown its potential in anticancer properties, evidence is lacking on its effect on skin carcinogenesis, but there is scientific support for its potential. Genistein has been found to have chemopreventive and strong anticancer activities. It has been shown to inhibit the activity of tyrosine protein kinase (TPK), topoisomerase II (Topo II), and ribosomal S6 kinase (RS6K) in cell culture. It has also been shown to inhibit growth of the ras oncogene and decrease PD6F-induced c-fos and c-jun expression in fibroblasts. Experiments were conducted to prove that genistein substantially blocks subacute and chronic UVB- and PUVA-induced cutaneous damage (Box 32.1; Figs 32.2 and 32.3).

Box 32.1 Clinical effects of genistein

image Preventive and therapeutic effects on the following in animals and humans:

Breast cancer

Prostate cancer

Postmenopausal syndrome

Osteoporosis

Cardiovascular disease

image Inhibits chemical carcinogen and UV light-induced skin carcinogenesis, photoaging, and photodamage

image Inhibits skin tumor formation post UVB radiation

image

Fig. 32.2 (A–C) Effect of genistein on UVB-induced acute skin burns in mice

image

Fig. 32.3 (A–C) Effect of genistein on histologic alterations in mice exposed to UVB

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