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RATIONALE FOR FIBROMYALGIA/CFS FATIGUE

It is well known that one of the major symptoms of fibromyalgia is muscle fatigue, while general fatigue is more characteristic of CFS. Both of these responses may be explained at the biochemical level by including fungi as a major contributory factor in the etiology of these diseases.¹²²

Cyclopiazonic Acid
One of the primary mycotoxins produced by Aspergillus as well as Penicillium species is cyclopiazonic acid. This toxin is also produced by species of Fusarium and Alternaria.¹⁰⁹ Cyclopiazonic acid is formed from certain species of Penicillium, including P. roqueforti used in the manufacture of Roquefort cheese (also known as "blue cheese"). Other blue-veined cheeses are Gorgonzola and Stilton.

The mechanism of action of cyclopiazonic acid is illustrated in Figure 7.(15KB .pdf) In muscle cells, the calcium required for muscle contraction is held in a subcellular organelle or compartment known as the sarcoplasmic reticulum (SR). There are two kinds of receptors (calcium pumps) found in the bilayer lipid membrane surrounding this storage. One is the receptor for inositol triphosphate (IP3), mentioned previously in relation to the pain mechanism. IP3, which, when bound to its receptor on the SR, allows the efflux of calcium into the cytosol and eventually results in muscle contraction. Once released into the cytosol, calcium must be returned to the SR storage chamber through a second type of calcium pump. This process requires energy and employs an ATP-driven pump known as Ca⁺²-ATPase because of its consumption of ATP (the energy molecule). Cyclopiazonic acid inhibits the activity of this pump, allowing an accumulation of calcium in the cytosol.¹¹⁰

The IP3 receptor that releases calcium from the SR into the cytosol is activated by adenophostins A and B (agonists). These mycotoxins are produced by Penicillium brevi-compactum and consist of phosphorylated adenine (found in one of the units of RNA/DNA). These substances mimic the action of inositol triphosphate (IP3) and are 100 times more effective in releasing calcium from the SR.¹¹¹ The net result of these two mycotoxins (cyclopiazonic acid and adenophostins) is to increase the calcium concentration of the cytosol, having a damaging effect on the mitochondria.¹¹² See Figure 7 (15KB .pdf) and Figure 8. (16KB .pdf)

Cyclopiazonic acid has a negative effect on cardiac muscle accompanied by marked prolongation of the contraction duration, probably through inhibition of SR function.¹¹⁰

Radioactive cyclopiazonic acid was used as a tracer in a study to determine the site of action of an administered dose. Skeletal muscle tissue contained 48% of the radioactive dose six hours after either ip or ig administration.¹¹³

Gliotoxin
Gliotoxin is a mycotoxin produced by Aspergillus fumigatus that has immunosuppressive properties.¹²⁰

Creatine is a simple organic substance found abundantly in muscle. Creatine is capable of binding a phosphate group and acting as a phosphate donor to adenosine diphosphate (ADP), forming adenosine triphosphate (ATP). Since muscles require ATP for muscle contraction, a quickly available source of ATP in times of stress is greatly desirable. Gliotoxin inhibits creatine kinase, leading to lowered ATP and muscle fatigue.¹¹⁴ See Figure 9. (12KB .pdf)

In vitro treatment of splenocytes with gliotoxin revealed relative decreases in CD4+ and increases in CD8+ T-cells, similar to one characteristic of AIDS.¹¹⁵

Chemistry of Cyclopiazonic Acid and Gliotoxin
If we look at Figure 11A (15KB .pdf), which shows the chemical structures of cyclopiazonic acid and gliotoxin, we might ask why cyclopiazonic acid is called an acid, since there are no carboxylic acid groups present. Two structures convey acidity to this molecule. The pyrrole ring (designated A) contains two unsaturations that withdraw electrons from the nitrogen atom, thereby making it more positive and repelling the hydrogen atom (proton). Ring C carries two carbonyl groups (C=O) and one ethylenic group (C=C). These unsaturated groups are electron-withdrawing in relation to the sole hydroxy group (-OH), making the oxygen atom more positive and repelling the attached hydrogen atom (proton). The result of these proton repulsions is to make either the oxygen of the –OH group or the nitrogen of the =NH group (or possibly both) negatively charged. An acid is a substance capable of releasing protons into solution.

The two methyl groups (-CH₃) attached to ring B are electron-contributing, making the tertiary nitrogen (bound to three carbon atoms) shared by fused rings B and C more basic (more able to bind a proton). Thus, the protons liberated from either the –OH or the =NH groups are capable of binding to the basic nitrogen shared by rings B and C, thereby becoming a four-bonded nitrogen carrying a positive charge. This, combined with the negative =N^- or negative –O^- atoms, form what is known as an "internal salt" or zwitterions, in which both the positive and negative charges of the salt are present in the same molecule. See Figure 11B.(14KB .pdf)

The presence of these charged groups on the same molecule enable cyclopiazonic acid to have great affinity for the Ca⁺²-ATPase on the surface of the SR and block its pumping action for the Ca⁺² ion.¹¹⁰

The most significant chemical feature of gliotoxin is the transannular disulfide linkage (-S-S-), also explaining its mode of action. The disulfide form shown in Figure 11A (15KB .pdf) may be reduced, breaking the bond between the two sulfur atoms and replacing them by two –SH (sulfhydryl) groups. In this form, either of the –SH groups may form a disulfide linkage with a similar group in a protein, thereby inactivating the protein (including enzymes).¹¹⁶ See Figure 11C.(14KB .pdf) Gliotoxin is also known to cause breaks in either single- or double-stranded DNA.¹¹⁷

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