Page 26 - FPGEE Medicinal and Organic Chemistry Q&A Book

Krisman

267. (d) Thioguanine (Tabloid) and
O NH
mercaptopurine (Purinethol) are classified as 2
purine antagonists. Thioguanine is indicated for
N N
the treatment of nonlymphocytic leukemias. HN N
Fluorouracil, methotrexate, capecitabine,
floxuridine and pemetrexed are classified as py- NH 2 N N N N
rimidine antagonists. H H
Guanine Adenine (6-aminopurine)
268. (c) Rimantadine (Flumadine) is structur-
ally and pharmacologically related to NH
2 O
amantadine (Symmetrel). Rimantadine appears
to be more effective than amantadine against CH 3
N HN
influenza A infection with fewer CNS side
effects.
NH 2 CH 3 O N O
NH 2 CH H N
H
Cytosine Thymine (5-methyluracil)

O

HN
Amantadine Rimantadine

O N
269. (a) Guanine is one of the five main H
nucleobases found in the nucleic acids DNA and
Uracil
RNA, the others being adenine, cytosine, thym-
ine, and uracil. With the formula C H N O, gua-
5 5 5
nine is a derivative of purine, consisting of a 270. (a) Cidofovir (Vistide) is a synthetic acy-
fused pyrimidine-imidazole ring system with clic pyrimidine nucleotide analogue of cytosine.
conjugated double bonds. Being unsaturated, the Cytosine is one of the five main bases found in
bicyclic molecule is planar. The guanine nucleo- DNA and RNA. It is a pyrimidine derivative,
side is called guanosine. with a heterocyclic aromatic ring and two sub-
stituents attached (an amine group at position 4
Acyclovir (Zovirax), chemical name
and a keto group at position 2). The nucleoside
acycloguanosine, is a guanosine analogue
of cytosine is cytidine. Three nucleobases found
antiviral drug. One of the most commonly-used
in nucleic acids (cytosine, thymine, and uracil)
antiviral drugs, it is primarily used for the treat-
are pyrimidine derivatives:
ment of herpes simplex virus infections, as well
as in the treatment of herpes zoster (shingles).
NH
2 O O
CH 3
N H N HN

O N O N O N
H H H
Cytosine Thymine (5-methyluracil) Uracil

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