chapter  30
36 Pages

Role of Antioxidants in Sun Care Products

Introduction 604

UV-Induced Chemical and Biochemical Changes:

Causes and Consequences 605

Photosensitizer and Reactive Oxygen Species 605

Iron and Copper 605

Matrix-Degrading Metalloprotease 607

Antioxidant Defenses of the Skin 609

Antioxidant Defense Enzymes 609

Low Molecular Weight Antioxidants 610

Photoprotection of Human Skin Using Antioxidants and Other

Photoprotectants 611

Vitamin E and Its Derivatives 612

Vitamin C and Its Derivatives 614

Carotenoids 615

Plant Polyphenolics 617

Tea Polyphenols 618

Silymarin 618

Emblica Antioxidant 619

Combination of Antioxidants 620

Unconventional Photoprotectants 621

Selenium 622

Zinc 622

Chelating Agents 622

Compatible Solutes 623

Retinoids 623

Dihydroxyacetone 624

Commercial Products 624

Conclusions 624

References 629

INTRODUCTION

Sun is the great initiator of photochemical reactions, which provides energy

that sustains plant life and maintains human health. It warms the earth and

furnishes solar energy, and in humans, activates synthesis of vitamin D for

utilization by the body to help it absorb calcium and other minerals. As the

outermost barrier of the body, the skin is directly exposed to a pro-oxidative

environment. The effects of ultraviolet (UV) radiation from sun exposure can

induce or exacerbate oxidative attack leading to the generation of reactive

oxygen species (ROS) and other free radicals. The most severe consequence

of photodamage is skin cancer. Less severe photoaging changes result in

wrinkling, scaling, dryness, and uneven pigmentation consisting of hyper-

and hypopigmentation (1-3).