Chemistry Reference
In-Depth Information
group of structurally related compounds designated as statins is now widely used
for the prevention and treatment of cardiovascular disease (80). Statins exert
their desired effects via the lowering of low-density lipoprotein and probably
also via reduced prenylation of small G-proteins of the Ras protein family that
are involved in proinflammatory signaling. The highly pleiotrophic mevalonate
pathway is the source of numerous other highly important metabolites including
coenzyme Q10 (
97
). However, a review concludes that the suppression of
coenzyme Q10 biosynthesis, which can be expected as a side result of statin
therapy, is not a significant cause of rhabdomyolysis, a dreaded side effect of
statin therapy (81).
10.3.5 Modulation of Vitamin D Biosynthesis by Environmental Factors
Fair-skinned humans face a dilemma because ultraviolet light exposure carries
the risks of carcinogenesis and skin aging, whereas insufficient ultraviolet light
carries the risk of vitamin D
3
(
94
, Fig. 10.11) insufficiency. The case is unique in
so far as an endogenous biosynthetic pathway is subject to regulation by external
lifestyle factors such as ultraviolet exposure and the use of chemical and physical
sunscreens. Recent studies indicate that vitamin D deficiency is wide spread in the
human population and is a risk factor for a wide variety of conditions, including
cancer and autoimmune disease (82). The dilemma of ultraviolet protection and
vitamin D sufficiency can be addressed easily by vitamin D supplements.
10.4 BIOTECHNOLOGY
10.4.1 Harnessing Biosynthetic Pathways for Vitamin Production
Certain vitamins that serve as coenzymes (vitamin C) or as precursors of coen-
zymes (all B group vitamins and certain carotenoids) are commercially produced
in bulk amounts, which are used for human nutrition and animal husbandry, as
antioxidants (vitamins C and E) and food colorants (vitamin B
2
, carotenoids).
Only a fraction of technically manufactured vitamins is used for inclusion in
drugs.
Vitamin B
12
is produced exclusively by bacterial fermentation technology.
The chemical synthesis of vitamin B
2
has been superseded during the past two
decades by fermentation processes using bacteria and yeasts. Carotene, various
other carotenoids and vitamin A are produced by chemical synthesis, but a variety
of biotechnological processes have been also been explored for their production.
Notably, vitamin A deficiency continues to be a major cause for acquired blind-
ness in developmental countries, although vitamin A and
β
-carotene, which serves
a provitamin, can be produced at modest cost and in virtually unlimited quantity
by existing technology. At least certain steps of the various technical vitamin
C processes are also conducted by fermentation. For various other vitamins,
biotechnological production may become competitive in the future.
