Krebs, Citric acid or Tri-carboxylic acid cycle is the mechanism through which, the powerhouse of the cell (mitochondria) extracts Hydrogen present in the carbon backbone of foods, to be oxidized through a process called oxidative phosphorylation to produce high-energy molecules plus water, in all aerobic organisms that can not live without Oxygen.
The starting material of this cycle is Citric acid. It is a 6-carbon molecule that is produced by condensation of the 4-carbon molecule Oxaloacetate with the 2-carbon molecule Acetyl-Coenzyme A.
All the metabolites dealt with mitochondria can be exchanged with cytoplasm directly or indirectly, through permeases (antiporters) present in its inner membrane, so that it can take up substrates of oxidation and export energy rich products, as well as molecules needed for anabolism (biosynthesis) of the cell.
Coenzyme A is crucial for the activity of the mitochondria and for fat biosynthesis. During acne formation, both anabolism and catabolism (breakdown of metabolites to produce energy) are highly active, and the cell may decline producing energy in favor of fat biosynthesis in some tissues.
Adding Coenzyme A or its precursors to the system restores the cell ability to perform production of both energy and fat efficiently, resulting in prevention of acne formation.