ABSTRACT
Introduction 17
Amino Acids: Basic Features 18
Existence and Roles of Amino Acids in the Skin 18
Harmonized Integrity of Skin Function with Amino Acids 30
Effective Amino Acid Delivery into Skin 30
Amino Acid Derivatives for Extended Applications 31
Conclusion 34
References 34
INTRODUCTION
Amino acids are molecules with both an amino group and a carboxylic group.
There are 20 kinds of naturally occurring amino acids with optically active struc-
tures at a-position (L-amino acids) except glycine (Gly). In their preface of Chemistry of the Amino Acids in 1961, Greenstein and Winitz said, “Few prod-
ucts of natural origin are versatile in their behavior and properties as are the
amino acids, and few have such a variety of biological duties to perform” (1).
Subsequently, significant progress has been made on the knowledge of amino acids,
and technical achievements to utilize such progress are remarkable, including
cosmetic and cosmeceutical applications. This is because of the market growth
and cost reduction of certain amino acids for many industrial applications. For
example, in food applications there is a huge and still growing consumption
generated for glutamic acid (Glu) and Gly as food additives and aspartic acid
(Asp) and phenylalanine (Phe) as raw materials of the artificial sweetener aspar-
tame. Consumption of lysine (Lys), methionine (Met), and threonine (Thr) is
expanding for the animal food additives market. Cysteine (CysH) and proline
(Pro) are major amino acids utilized in the flavor industry to manufacture
natural flavors by the Milliard reaction with sugars. Health food and pharma-
ceutical intermediates are other rapidly growing markets for many amino
acids. In this chapter, the role of amino acids and their derivatives are reviewed
as functional molecules for cosmeceutical applications.
