Glaser's "Chemistry is in the News"
To Accompany Wade Organic Chemistry 4/e.
Chapter 23. Carbohydrates and Nucleic Acids.
Every year, the average American consumes 26.3 gallons of coffee 1. Despite the fact that coffee consumption has been linked to heart disease, people around the world continue to drink this popular beverage in vast quantities. Surely there has to be some positive consequences to drinking coffee. This is exactly what a University of California chemist has found through his research. Tayayuli Shibamoto has found that the Maillard reaction, which occurs during the coffee brewing process, produces an aroma containing approximately 300 heterocyclics such as maltol and 5-hydroxymethylfurfural (see illustrations below). Alone these heterocyclic compounds have minimal potency; however, when combined in a freshly brewed cup of coffee, the antioxidative activity of these compounds is equivalent to that of three oranges! Whether you drink decaffeinated or regular coffee the antioxidative properties will be the exact same. Without antioxidants, tissue damage, cancer, and diabetes can occur due to the process of lipid peroxidation and other types of oxidative damage. This means that coffee contains cancer and age fighting heterocyclics whose effects are similar to other antioxidants, including vitamin C and vitamin E. Antioxidants help to block some of the unwanted effects that oxygen can have on the living tissue in the body.
Although Shibamoto has shown that coffee has important antioxidative properties, the undesirable effects of coffee still need to be considered. For example, the organic acid coffee contains and the caffeine it sends through your veins leads to upset stomachs and jittery nerves. Therefore, additional research needs to be conducted before coffee is to be considered a health tool.
The context of the article and its supporting links will aid in answering the questions below.
Question 1: Why is the consumption of coffee, rather than just smelling it's aroma, necessary in order to obtain all the antioxidative benefits of the heterocyclics?
A. The aroma that results from coffee after being brewed only contains a small amount of antioxidant activity. When you actually drink the coffee, you are getting the maximum amount and benefit of heterocyclics.
Question 2: During the process of lipid peroxidation, an oxygen radical reacts with the fatty acid attached to the lipid producing a chain reaction that begins to destroy the tissue. This reaction is completed through a series of steps called initiation, propagation, and termination. Look at the link on lipid peroxidation, and briefly summarize what is taking place during each step.
A. In initiation, the oxygen radical removes a hydrogen from the fatty acid group attached to the lipid bilayer, forming a lipid radical. During propagation, the reaction continues with the lipid radical abstracting another hydrogen from an adjacent fatty acid. This results in a second lipid radical. This process continues throughout this chain reaction until termination is reached. This occurs when two radicals join together or when a stable product is formed ending the reaction.
Question 3: By using a picture of the caffeine molecule, come to a conclusion on how the lone pairs on the oxygen and nitrogen atoms in the molecule help to make this drug more absorbent?
A. The lone pairs on the oxygen as well as the nitrogen groups in the heterocycle can readily form a hydrogen bond with the water in the blood, thus making the caffeine more hydrophilic and easily absorbed.
Question 4: Although the heterocylic chemistry concerning coffee is still in the identification state, we can compare the total antioxidative activity to that of oranges which notably contains vitamin C. By using the supplied link, explain why the anti oxidative activity of vitamin C is different to that of other vitamins (mainly vitamins A and C).
A. Vitamin C acts by binding and protecting many other anti-oxidants from damage that would occur due to oxidative reactions.
Question 5: Why does caffeine free coffee and regular coffee have the same antioxidant health effects considering only the heterocyclic chemistry?
A. The only difference between the two types of coffee is that one contains caffeine and the other does not. They still have the same effect because the antioxidant benefits are not found in the caffeine but rather in the heterocyclic compounds found in all coffee. The heterocyclic compounds produced by the Maillard reaction and the antioxidative properties they possess are independent of caffeine.
Question 6: Your dear old mother drinks an average of 3 cups of coffee per day. You are worried about her health, but you also know that coffee contains many antioxidants which have been proven to help prevent tissue damage and disease. By looking at both the benefits and the risks associated with drinking coffee, should you encourage your mother to drink more hoping to improve her health, or urge her to reduce her consumption?