This news item was created by students Lesley Davis, Jr., Scott Dudley, Kelly Mandl, Diana Rau, Jeff Sindelar, and TJ Soyoye as part of their Chemistry 212 Collaborative Group Activities in WS00 under the guidance of Prof. Rainer Glaser.

Glaser's "Chemistry is in the News"
To Accompany Wade Organic Chemistry 4/e.
Chapter 24. Amino Acids.

For each of the following questions, please refer to the following article:


FAKE TANS ARE LEAVING FEWER STREAKS
by Angela Pirisi (The Gazette [Montreal], 1998)
 

Editorial Comments



Beauty is in the eye of the beholder and a "beautiful tan" is something sought after by millions upon millions of people yearly in the United States. We have all heard the catch phrases since we were old enough to slip on our first swimsuit, from the aforementioned 'beautiful tan' to the ever so ironic 'healthy tan'. The society we live in places great emphasis on appearance, and the ritual of tanning is a major factor in that appearance.

Unfortunately, the tan that we have all grown to love and has proved to have some long-term shortcomings, with a greatly increased likelihood of skin cancer being at the top of the list.

A silly as it sounds, people still choose the short-term appearance and disregard the proven long-term adverse effects. Old habits die hard, and sadly the rates of deaths from skin cancer are rising accordingly.

Fortunately, another catch phrase is beginning to be heard, the so-called 'fake tan'. The potential for profit is fueling the development of chemicals that provide a tan equivalent to that of the best beach bum's tan-- one with none of the harmful risks.

Males and females alike are concerned about how pale their skin is; however, they still have to worry about the growing threat of skin cancer. What could be done to give skin the bronzed look in the middle of the winter without someone worrying about the harmful UV rays absorbed while sunbathing?

For years many have relied on the help of 'fake tans' straight from the bottle. Often, however, many people ignore this route because these self-tanners are streaky at best and have a foul odor to them. The bad smell is associated with sugar-like chemicals such as dihydroxyacetone (DHA). Recently, thought, there have been wonderful advances in the field of self-tanners, giving a more natural look with much less of a foul smell.

The DHA in these self-tanners form colored complexes with the amino acids in the skin; these kinds of tan vary from person to person because of other factors like skin thickness, skin pH, melanin levels, and the amount of melanoids produced within the skin. Strange discolorations and inevitable streaking have been the direct result of these other factors. Not every individual's skin is the same, and what may work for one person and produce great results may not work at all for someone else. The different acidity levels of most everyone's skin produce different color results for everyone.

These so-called 'fake tans' are a wonderful alternative to the real thing; they even help those persons with skin diseases or pigment problems that prevent them from being exposed to large amounts of UV rays. They also come in a variety of types: some self-tanners [like those from Lanc™me and Christian Dior] contain alpha-hydroxy acetone (AHA), and some [like those from Clarin] contain sunsreen. The included article details self-tanners and DHA and some of these products and provides information that can educate 'tanners' and 'fake-tanners' alike.

Pertinent Text References
Chapter 24
    - amino acids, peptides, proteins, and acidity:  pg 1119
    - reactions of amino acids:  pg 1133
Chapter 18
    - ketones and aldehydes:  pg 785



Questions

Question 1:  Compare the structures and uses of AHA and DHA. Include IUPAC names for both.

Answer

Question 2:  How do melanoidins and melanins differ?

Answer

Question 3:  What is the chemical reaction that is responsible for the unpleasant odor associated with tans?

Answer

Question 4:  According to the article, the effects of a fake tan are due to a few factors. Describe those factors and explain how skin pH alters the effect.

Answer

Question 5:  There have been many improvements made to self-tanning products, as described in the article. What are some of these improvemnets and what other improvements may be made to self-tanners to meet the consumers needs of the future?

Answer