7.6.3 Inhibitors of viral protein synthesis
The principal compounds that act as inhibitors of viral protein synthesis are the
interferons. These compounds are members of a naturally occurring family of
glycoprotein hormones (RMM 20 000–160 000), which are produced by nearly all
types of eukaryotic cell. Three general classes of interferons are known to occur
naturally in mammals, namely; thea-interferons produced by leucocytes,b-
interferons produced by fibroblasts andg-interferons produced by T lympho-
cytes. They form part of the human immune system. It is believed that the presence
of virons and pathogens in the body switches on the mRNA that stimulates the
production and release of interferons. These interferons are thought to stimulate
the production of proteins that inhibit the synthesis of viral mRNA and viral
proteins.a-Interferons also enhance the activity of T killer cells.
The formation and release of interferon by viral and other pathological
stimulation has resulted in a search for chemical inducers of endogenous inter-
feron. Administration of a wide range of compounds has resulted in induction
of interferon production. However, no clinically useful compounds have been
found for humans, although tilorone is effective in inducing interferon in mice.
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H 3 CTilorone7.7 Questions
(1) Describe the main differences between each of the following:
(a) fungicidal and fungistatic drugs;
(b) agonist and antagonist and
(c) eukaryotic and prokaryotic cells.(2) What are ionophores? How do they act?
(3) Suggest reasons for bacterial resistance tob-lactam drugs.
(4) Describe the main features of competitive, non-competitive and irreversible
inhibition of enzymes.(continues overleaf)
QUESTIONS 157