17.4^17.4. INTERESTING CARBOXYLIC ACIDS IN CONSUMER PRODUCTS AND MEDICINES^512^513^,,^27533^27585%
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17.4
INTERESTING CARBOXYLIC ACIDS IN CONSUMER PRODUCTS AND MEDICINES
HEALTH NOTE

Ginkgo trees have existed for over 280 million years. Extracts of the ginkgo tree have long been used in China, Japan, and India in medicine and cooking.

Simple carboxylic acids have biting or foul odors.

17.4A
FOCUS ON HEALTH & MEDICINE
SKIN CARE PRODUCTS
CONSUMER NOTE

α-Hydroxy acids are used in skin care products that are promoted to remove wrinkles and age spots.

Several skin care products that purportedly smooth fine lines and improve skin texture contain α-hydroxy acids. α-Hydroxy acids contain a hydroxyl group on the α (alpha) carbon to the carboxyl group. Two common α-hydroxy acids are glycolic acid and lactic acid. Glycolic acid occurs naturally in sugarcane, and lactic acid gives sour milk its distinctive taste.

Do products that contain α-hydroxy acids make the skin look younger? α-Hydroxy acids react with the outer layer of skin cells, causing them to loosen and flake off. Underneath is a layer of healthier looking skin that has not been exposed to the sun. In this way, these skin products do not actually reverse the aging process; rather, they remove a layer of old skin that may be less pliant or contain small age spots. They can, however, give the appearance of younger skin for a time.

PROBLEM 17.12

Label the chirality center in lactic acid. Draw both enantiomers of lactic acid (Section 15.3).

PROBLEM 17.13

Which compounds are α-hydroxy acids?

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17.4B
FOCUS ON HEALTH & MEDICINE
ASPIRIN AND ANTI-INFLAMMATORY AGENTS

Three common pain relievers that are also anti-inflammatory agents contain a carboxyl group—aspirin, ibuprofen, and naproxen.

How does aspirin relieve pain and reduce inflammation? Although aspirin is the most widely used pain reliever and anti-inflammatory agent and has been sold since the late 1800s, its mechanism of action remained unknown until the 1970s. At that time it was shown that aspirin blocks the synthesis of prostaglandins, carboxylic acids containing 20 carbons that are responsible for mediating pain, inflammation, and a wide variety of other biological functions.

Prostaglandins are not stored in cells. Rather, they are synthesized on an as-needed basis from arachidonic acid, an unsaturated fatty acid with four cis double bonds. Aspirin relieves pain and decreases inflammation because it prevents the synthesis of prostaglandins, the compounds responsible for both of these physiological responses, from arachidonic acid.

The 1982 Nobel Prize in Physiology or Medicine was awarded to John Vane, Bengt Samuelsson, and Sune Bergstrom for unraveling the details of prostaglandin synthesis, thus showing how aspirin acts.

PROBLEM 17.14

Which compound, PGF (a prostaglandin) or arachidonic acid, is more water soluble? Explain your choice.