Jonathan T - Clemson University



Jonathan T. Babb

Jennifer Burns

Erinn Stefanich

November 18, 2001

Chem 224

Dr. Arya

Cipro for Chickens Sets Off Antibiotic Debate

Note: This link is from NYTimes Online and requires login.

Editorial Comments.

After the September 11 attacks on America and the subsequent Anthrax incidents, a frenzy has erupted over the possibility of bioterrorism. A drug which immediately appeared on the front page of almost every major newspaper was Cipro®. This drug was cited as one of the only antibiotics which possesses the capability to fight an Anthrax outbreak. ()With antibiotic resistance on the rise, the continued effectiveness of Cipro related medications has become a crucial issue. This article discusses the possibility of Cipro’s sister drug Baytril®, which is used widely in poultry and livestock applications, becoming a facilitator of microbial resistance to the Cipro used for human patients. ()

Two different antibiotics are discussed in this article. Cipro and Baytril are both quinolone compounds. They have somewhat similar structures. The structure of Cipro can be found at () by searching either for “Cipro” or for “Ciprofloxacin.” The chemical structure of Baytril ®, otherwise known as enrofloxacin was more difficult to find on the internet. These structures are shown below.

Baytril® (Chemfinder) Cipro® (Chemfinder)

[pic][pic]

Baytril is the tradename of a compound which has the following systematic name: 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid. Baytril is highly related to Cipro which has the following systematic name: 1-cyclopropyl-7-(4-ethyl-1-piperazinyl)-6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid. ( & )

These two drugs are both derivatives of quinoline, a heterocyclic aromatic structure consisting of two joined benzene rings with a nitrogen atom substituted for one carbon. The quinoline chemical structure provides many sites which, under certain reaction conditions, can be substituted with various functional groups. Chapter 11 in our textbook Organic Chemistry, deals with the topic of heterocyclic aromatic compounds of this type. Other chapters in the book regarding functional groups and methods of aromatic substitution etc. also would pertain to the synthesis of this drug. Most likely both compounds, from their starting materials, undergo reactions such as electrophilic aromatic substitution to introduce the fluorine component onto the compound. () Many other processes to introduce functional groups such as the carboxylic acid can be found in the textbook. Chapters 19 and 20 apply to the carboxylic acid group.

This article presents an issue which is very pertinent to the time in which we live. The article introduces the reader to two differing viewpoints. These two perspectives include those who propose removal of Baytril and those who oppose its discontinuation. Nevertheless, this article does not provide any scientific evidence to support either conclusion. Instead the article focuses on introducing the issues and defining the nature of the two drugs in question. This is one of the many examples from news stories where in-depth questioning of the material can lead to a better understanding of the issues at hand.

Questions:

1. How many different functional groups are on the Cipro compound? On the Baytril compound? What are they? (Chapters 2 & Inside front cover).

2. Are these compounds aromatic and why? (Chapter 11, 430-432).

3. How is the carbonyl group added to quinoline during the formation of Baytril? (Chapter 24, 958-959).

4. Write the IUPAC names for both of the following compounds. (Various Chapters)

5. How do these compounds inhibit bacterial infections ? ()

Answers:

1. The Cipro chemical structure contains five functional groups. These include a fluorine as a halogen substituent, a carboxylic acid, a cyclo-propyl alkyl group, a ketone, and 4-ethyl-1-piperazinyl as another substituent. The Baytril chemical structure contains five functional groups as well. These include a fluorine halogen substituent, a carboxylic acid, a ket one, a cyclo-propyl group, and 1-piperazinyl as another substituent.

2. Both Cipro and Baytril contain one aromatic ring. This ring is adjacent to another six-membered ring structure which is not aromatic.

3. The ketone is introduced to the compound by an oxidation procedure. (Carey 958).

4. The IUPAC name for Cipro is 1-cyclopropyl-7-(4-ethyl-1-piperazinyl)-6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid. The IUPAC name for Baytril is 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid.

5. The two drugs inhibit bacterial infections by the following method:

“Manufacturers of fluoroquinolones emphasize the fact that these drugs have very different mechanisms of action from such groups as the beta-lactams and aminoglycosides. Although the exact mechanism is unknown, it is known that the quinolones inhibit the A subunit of DNA gyrase in bacteria. The gyrase, a type II topoisomerase, nicks and seals DNA during replication. Without the gyrase, DNA cannot be replicated, then repacked in daughter cells. The quinolone action also inhibits relaxation of supercoiled (packed) DNA necessary for DNA replication and increases double-stranded DNA breakage.” ( & )

Group Dynamics:

Our group felt as thought this project helped with the interaction of organic chemistry and the real world, but it took a lot of time and effort to get all the information needed. It was a good assignment and it will definitely help out with the grades in the class. This should be an extra credit assignment for this class because it helps you relate to it’s importance and not think that it is pointless to learn. Our group had a problem on schedules and getting together “on time,” but we got the work done. All the members in the group were cooperative and tried their best to put their knowledge in to the project. We all got along and worked well together. This helped us get to know other people in the class and form study groups for future tests and projects.

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