5. ONIUM COMPOUNDS
183
Information as to the biological significance of these compounds,
their mode of synthesis, and the role which they fulfill in the various
species in which they are found is extremely uneven. Thus practically
nothing is known about the biosynthesis of carnitine and its function in
muscle or about the role, origin, and fate of the betaines and the thetins
in the plants in which they are found. On the other hand considerable
information has accumulated on the biochemistry of certain other sulfonium compounds and their participation in biological transalkylation
reactions. Likewise the biological and biochemical role of certain thiazolium and pyridinium compounds is relatively fully understood and is
closely related to the well known coenzyme functions of thiamine pyrophosphate and of the pyridine nucleotides.
Largely as the result of work on enzymatic mechanisms involved in
transalkylation reactions from sulfonium or quaternary ammonium compounds and in base exchange reactions utilizing thiazolium or pyridinium compounds, the concept has emerged in recent years that onium
compounds are energy-rich in the same sense in which certain pyrophosphate or acyl phosphate compounds and acyl mercaptan compounds
are energy-rich, namely, they can serve biologically as sources of chemical energy for biosynthetic purposes. This concept will be discussed in
detail in a later section but must be anticipated now for it will be referred to throughout the text and it is the main raison d'etre for this
chapter.
Finally, it should be pointed out that some onium compounds are
exceedingly active biologically and in some cases are among the most
potent pharmacological agents known. Little or no knowledge is available, however, of the intimate mechanism by which they exert these
effects.
It is clearly beyond the scope and limits of this chapter to review
fully all aspects of the chemistry and biology of naturally occurring
onium compounds. This review will attempt to present an over-all view
of the natural distribution and the significant chemical properties of
onium compounds and attempt a more complete discussion of those
Holmes, eds.), Vol. 3, p. 313. Academic Press, New York, 1953.
l V. Erspamer, Rend,
sei. farmitalia 1, 1 (1954).
m V. Erspamer, personal communication (1900).
n Jahkns
(98). ° Wiehler and Marion (94).
p E. S. Stern, in "The Alkaloids" (R. H. F. Manske
and H. L. Holmes, eds.), Vol. 4, p. 275. Academic Press, New York, 1954. * C. P.
Jansen, in "The Vitamins" (W. H. Sebrell, Jr., and R. S. Harris, eds.), Vol. 3, p. 472.
Academic Press, New York, 1954.
r F. Schlenk, in "The Enzymes" (J. B. Sumner and
K. Myrbäck, eds.), Vol. 2, Part 1, p. 250. Academic Press, New York, 1951.
β Perlzweig
et at. (101).
t Kutscher and Ackermann (97); Gasteiger et al. (99).
u Cantoni (23).
»L. E. Craig, Chem. Revs. 42, 285 (1948). « Challenger and Simpson (109). * See
references 122-127.
* McRorie et al. (151).
z Challenger and Hayward (153).
183
Information as to the biological significance of these compounds,
their mode of synthesis, and the role which they fulfill in the various
species in which they are found is extremely uneven. Thus practically
nothing is known about the biosynthesis of carnitine and its function in
muscle or about the role, origin, and fate of the betaines and the thetins
in the plants in which they are found. On the other hand considerable
information has accumulated on the biochemistry of certain other sulfonium compounds and their participation in biological transalkylation
reactions. Likewise the biological and biochemical role of certain thiazolium and pyridinium compounds is relatively fully understood and is
closely related to the well known coenzyme functions of thiamine pyrophosphate and of the pyridine nucleotides.
Largely as the result of work on enzymatic mechanisms involved in
transalkylation reactions from sulfonium or quaternary ammonium compounds and in base exchange reactions utilizing thiazolium or pyridinium compounds, the concept has emerged in recent years that onium
compounds are energy-rich in the same sense in which certain pyrophosphate or acyl phosphate compounds and acyl mercaptan compounds
are energy-rich, namely, they can serve biologically as sources of chemical energy for biosynthetic purposes. This concept will be discussed in
detail in a later section but must be anticipated now for it will be referred to throughout the text and it is the main raison d'etre for this
chapter.
Finally, it should be pointed out that some onium compounds are
exceedingly active biologically and in some cases are among the most
potent pharmacological agents known. Little or no knowledge is available, however, of the intimate mechanism by which they exert these
effects.
It is clearly beyond the scope and limits of this chapter to review
fully all aspects of the chemistry and biology of naturally occurring
onium compounds. This review will attempt to present an over-all view
of the natural distribution and the significant chemical properties of
onium compounds and attempt a more complete discussion of those
Holmes, eds.), Vol. 3, p. 313. Academic Press, New York, 1953.
l V. Erspamer, Rend,
sei. farmitalia 1, 1 (1954).
m V. Erspamer, personal communication (1900).
n Jahkns
(98). ° Wiehler and Marion (94).
p E. S. Stern, in "The Alkaloids" (R. H. F. Manske
and H. L. Holmes, eds.), Vol. 4, p. 275. Academic Press, New York, 1954. * C. P.
Jansen, in "The Vitamins" (W. H. Sebrell, Jr., and R. S. Harris, eds.), Vol. 3, p. 472.
Academic Press, New York, 1954.
r F. Schlenk, in "The Enzymes" (J. B. Sumner and
K. Myrbäck, eds.), Vol. 2, Part 1, p. 250. Academic Press, New York, 1951.
β Perlzweig
et at. (101).
t Kutscher and Ackermann (97); Gasteiger et al. (99).
u Cantoni (23).
»L. E. Craig, Chem. Revs. 42, 285 (1948). « Challenger and Simpson (109). * See
references 122-127.
* McRorie et al. (151).
z Challenger and Hayward (153).