Affiliations: Department of Biochemistry and Biophysics, Stockholm
University, Stockholm, Sweden | Rolf Luft Research Centre for Diabetes and
Endocrinology, Karolinska Institutet, Stockholm, Sweden | Institute of Biochemistry and Biophysics, Polish
Academy of Sciences, Warsaw, Poland
Abstract: Uptake of dietary coenzyme Q (CoQ) into organs is limited but there
are some exceptions such as adrenal glands and ovaries. Under deficient
conditions an optimal solution could be stimulation of the endogenous
synthesis. In rodent exercise, cold exposure and a few substances elevate the
CoQ levels to some extent. Investigations of the nuclear receptors
PPARα, RXRα and
LXRα&β did not answer
the question which nuclear receptor regulates CoQ biosynthesis and at present
we cannot design a ligand for upregulation of the synthesis. Upon ultraviolet
irradiation of CoQ a number of products are formed which influence the
synthesis of the mevalonate pathway lipids. Among them epoxidated derivatives
were identified. Upon chemical epoxidation of a series of polyisoprenoids it
was found that none of the tested poly-cis polyisoprenols had any effect but
some of the all-trans polyisoprenols stimulated CoQ synthesis and in some cases
also inhibited cholesterol biosynthesis. Tocotrienol epoxides were proved to be
very efficient, those having one epoxide in the side chain doubled or trebled
the CoQ synthesis while those with two epoxides additionally also inhibited
cholesterol synthesis by 50–90. The elevation of CoQ synthesis was
elicited by increased mRNA levels for biosynthetic enzymes while the inhibition
point in the cholesterol synthesis was localized to oxidosqualene cyclase.
