What is PQQ (Pyrroloquinoline quinine)?

Pyrroloquinoline quinine, also known as PQQ, is a redox cofactor and a polyphenolic compound usually derived in food plants. It is classified as an essential micronutrient because of its usefulness to the body. It is found in the cytoplasm of cells and helps with reduction reactions and oxidation. This compound is amazingly powerful at carrying out redox reactions, and can conduct about thirty to five thousand more cycles than the regular Vitamin C.

PQQ can be consumed as a dietary supplement to aid cellular energy production and mitochondrial health and to defend the body against oxidative stress. Its most notable aspect is the fact that it stimulates the spontaneous formation of new mitochondria in the body’s aging cells, and also triggers genes governing mitochondrial protection, reproduction, and repair. While PQQ helps the body in many different ways, here are its main benefits.


It is a strong neuroprotective compound that protects cognition and memory in aging humans. Studies conducted have shown that pyrroloquinoline quinine overturns the cognitive deterioration brought about by severe oxidative stress and helps people to perform better on memory tests. PQQ supplements stimulate nerve growth creation and discharge in neuron-supporting cells in the brain. This leads to improved memory function.

PQQ is an anti-aging defense for the top energy-exhaustive organs. Its top capacity as a superior anti-oxidant and cell signaling modulator makes it very effective in fighting age-related declines as well as degenerative diseases in the body’s most energy-intensive organs; the brain and heart.

PQQ hinders the gene known as DJ-1 from self-oxidizing. This gene leads to Parkinson’s disease if left unchecked. PQQ also prevents aggregation of alpha-synuclein and defends the nerve cells from the damaging effects of amyloid-beta protein; the compounds linked to Parkinson’s disease and Alzheimer’s disease respectively. Research shows that the mitochondria of a middle aged person and that of an old person is usually highly damaged. PQQ boosts the health of the mitochondria and reverses this situation.

PQQ hinders oxidative damage on the brain cells following ischemia-reperfusion injury (the oxidative damage and inflammation that is caused by the immediate return of nutrients and blood to tissues deprived of them by a stroke). PQQ also works effectively to protect your brain against any neurotoxicity that is induced by powerful toxins such as oxidopamine and mercury.

PQQ protects neurons by inhibiting the damaging effects of prolonged over-stimulation of neurons usually associated with seizures and neurodegenerative diseases. PQQ interacts with the brain’s neurotransmitter system in a beneficial manner. It protects the neurons by adjusting the NMDA receptor site. NMDA is a very powerful intermediary of “excitotoxicity,” a result of prolonged overstimulation of neurons linked to many neurodegenerative seizures and diseases.


PQQ promotes attention, cognition, and memory. People who take a PQQ supplement of 20 mg every day show improved performance in enhanced memory tests than those who don’t. When PQQ is taken together with coenzyme Q10, it improves the quality of life of old people as well as their mental status. It also prevents or slows down the age-related cognitive decline that occurs among old and middle aged people.


Damage from heart attack is usually inflicted via ischemia-reperfusion injury. PQQ supplements help reduce the size of the damaged areas resulting from acute heart attack. Studies carried out showed that this healing process occurs the whether PQQ is given before or after the heart attack. The supplements help reduce the size of the damaged areas and defend against heart muscle dysfunction. This suggests that giving PQQ supplements to a heart attack victim within the initial hours of medical response can offer significant benefits to them. PQQ also helps the heart’s muscle cells to resist severe oxidative stress by enhancing and preserving mitochondrial function.

What is PQQ’s Anti-Oxidant capacity and function in Mitochondrial Health?

Mitochondria are very vulnerable to destruction from oxidative damage because they function as the main engines for almost all bioenergy production in a person’s body. Mitochondrial dysfunction is widely recognized by scientists as a major biomarker of aging. Mitochondrial DNA possesses little protection against free radical damage, and therefore depends on antioxidants for protection. PQQ’s potent free radical-scavenging ability gives the mitochondria superior antioxidant protection because of its high molecular stability and ability to transfer energy directly within the mitochondria. Its exceptional molecular stability is unlike that of other antioxidants because it allows PQQ to perform numerous electron transfers without going through molecular breakdown.

PQQ is very effective in neutralizing hydroxyl and superoxide radicals, which are the two major causes of mitochondrial dysfunction. A study conducted at The University of California at Davis showed that PQQ is between 30 to 5,000 times more effective at sustaining mitochondrial energy production (redox cycling) than other antioxidant compounds such as Ascorbic Acid.

What is PQQ’s Role in Growth and Development?

PQQ’s critical function in growth and development comes from its exceptional ability to stimulate cell signaling pathways that are directly involved in development, function, and cellular energy metabolism. It encourages the natural growth of mitochondria in the body’s aging cells (Mitochondrial Biogenesis). This process helps in improving human health and longevity. Apart from this process, the only other methods known to activate mitochondrial biogenesis in old people are strict caloric restrictions, intense aerobic exercises, and specific medications such as Metformin and Thiazolidinediones (for diabetes). PQQ is therefore a crucial compound in enhancing mitochondrial function resulting in better output for the body’s energy cells.

PQQ is an essential compound that plays a critical part in the human body. Without it, a person can experience growth impairment, abnormal reproductive function, and compromised immune status. The immune system is very responsive to low amounts of PQQ and requires it just like other essential nutrients. When the body is deprived of PQQ, multiple defects occur in the body’s immune functions.

Mitochondria dysfunction has been linked to almost all killer diseases of aging, from type 2 diabetes, to Alzheimer’s disease, to heart failure. PQQ effectively stimulates mitochondria repair, reproduction, and protection. It also provides optimal defense against neural degeneration and gives powerful cardioprotection to ensure one lives a long and healthy life.

PQQ, Nitric Oxide, and Peroxynitrite

There have been a few of you concerned about pyrroloquinoline quinone and erectile dysfunction. Recently we received the following question:

…positive results in animal studies (show) relative avoidance of ischemic reperfusion injury following induced stroke in lab animals. This was due, I understand, to PQQ’s ability to block nitric oxide synthesis. This begs the question; do you think PQQ can cause male erectile dysfunction since normal function depends on adequate levels of nitric oxide?

Pyrroloquinoline quinone is a redox active nutrient that can scavenge various reactive oxygen species (ROS), such as superoxide radicals, which can act as deleterious oxidants. This is one of several aspects that make PQQ an effective anti-ischemic agent.

PQQ is unable to directly interact with nitric oxide. Research shows it doesn’t block nitric oxide synthesis, which in part addresses the concern about erectile dysfunction. Rather, pyrroloquinoline quinone’s effect on nitric oxide relates to it’s ability to reduce the levels of the major ROS derived from nitric oxide, a compound called peroxynitrite. Nitric oxide can react with superoxide radicals to form the product, peroxynitrite.

Peroxynitrite is an oxidant and nitrating agent that can severely damage a wide array of molecules in one’s cells, including DNA and proteins. With respect to PQQ, less peroxynitrite is formed, when the formation of superoxide is blocked or reduced, because of PQQ’s ability to act as an anti-oxidant.

PQQ and Parkinson’s disease

Regrettably, there are no clinical studies that been done to date to directly address whether PQQ is effective in the treatment of Parkinson’s disease, although the assertion is sometimes made in nutritional supplement-oriented blogs and websites less scrupulous than ours. However, there are a number of basic studies that appear promising, which suggest pyrroloquinoline quinone may be beneficial in slowing or altering the progression of Parkinson’s disease.

What is known to date? In studies using experimental animal models, PQQ does interact with the neurotransmitter systems. It appears to be a neuroprotective (also see the post, PQQ, glutamate, nitric oxide and N-methyl-D-aspartic acid receptors). PQQ could potentially protect against neurotoxicity induced by compounds that promote or produce Parkinson-like symptoms in laboratory animals. Moreover, PQQ in chemical assays inhibits the aggregation of alpha-synuclein, a process that is associated with the progression to Parkinson’s disease. Pyrroloquinoline quinone also seems to protect nerve cells by blocking new amyloid beta molecular structures from forming before they can cause cellular damage akin to what is observed in Parkinson’s disease. Although these observations are promising, questions nevertheless remain regarding how direct and specific the actions of PQQ are as they relate to altering the functions of alpha-synuclein and amyloid beta, if and when they are abnormally aggregated.

If you would like to do a deeper dive on this topic you should read:

1. Kobayashi, M; Kim, J; Kobayashi, N; Han, S; Nakamura, C; Ikebukuro, K; Sode, K. Pyrroloquinoline quinone (PQQ) prevents fibril formation of alpha-synuclein. 2006 Biochemical and Biophysical Research Communications 349: 1139–44.
2. Zhang JJ; Zhang RF; Meng XK. Protective effect of pyrroloquinoline quinone against Abeta-induced neurotoxicity in human neuroblastoma SH-SY5Y cells. 2009 Neuroscience Letters 464: 165–9.
3. Kim, J; Kobayashi, M; Fukuda, M; Ogasawara, D; Kobayashi, N; Han, S; Nakamura, C; Inada, M et al. Pyrroloquinoline quinone inhibits the fibrillation of amyloid proteins. Prion 4: 26–31.

PQQ and Reported Side Effects

The data for PQQ’s safety is excellent, at least for limited or short-term use (e.g. up to a year) in humans and longer-term use in animals. Long-term (multiple year) safety in humans remains to be assessed.  However, based on pyrroloquinoline quinone direct to market sales, it may be concluded that hundreds of individuals now take PQQ.  Some of these users tend to be aggressive about supplementation (including myself), so the chance that an interaction with PQQ may be adverse seems highly unlikely based on the lack of any published reports.

Although there are no direct studies on the potential interaction of PQQ with psychotropic drugs, several studies suggest that the idea is worth exploring.  What data that are available regarding cognition are in two animal studies and one human study (see below). The human study is well controlled and the results of the study suggest that PQQ alone or with CoQ10 may be useful for improving higher brain function. Likewise, the animal studies are supportive of this perspective.

To be very clear, not all these supplements and medicines work independently? The best answer about food supplementation and drug interaction is going to come from your personal physician and pharmacist. Although one can identify major mechanisms or even specific functions for given compounds, from a global physiological perspective, there can be cross talk between the numerous cell-signaling pathways that control cellular function and an enzyme cofactor may interact with numerous enzymes each with a specific function.

1: Takatsu H, Owada K, Abe K, Nakano M, Urano S. Effect of vitamin E on learning and memory deficit in aged rats. J Nutr Sci Vitaminol (Tokyo). 2009; 55:389-93.

2: Ohwada K, Takeda H, Yamazaki M, Isogai H, Nakano M, Shimomura M, Fukui K, Urano S. Pyrroloquinoline Quinone (PQQ) Prevents Cognitive Deficit Caused by Oxidative Stress in Rats. J Clin Biochem Nutr. 2008; 42:29-34.

3: Pyrroloquinoline quinone disodium salt improves higher brain function.  Medical Consultation and New Remedies 2011; 48(5): 519 – A Japanese food/supplement journal

Pyrroloquinoline Quinone and Probiotics

PQQ is a growth factor and chemical attractant for a number of bacteria. Bacteria defined as acidobacteria and methylotrophic bacteria produce PQQ.  Acidobacteria are common to soil and methylotrophs are organisms that can use reduced one-carbon compounds, such as methanol or methane, as the carbon source for their growth.  Of potential importance to human health, PQQ is also utilized as a cofactor by bacteria that do not normally produce it as a part of their metabolism.   A good example is Escherichia coli (E. coli), the gram-negative, rod-shaped bacterium that is commonly found in the intestine. When provided PQQ, E. coli utilizes it as an enzymatic cofactor in enzymes important to glucose and alcohol metabolism. Although it seems likely that PQQ supplements may alter metabolic features of E. coli, whether PQQ influences lactobacillus and other organisms that are utilized as probiotics remains to be examined.   Making the link between PQQ and probiotic use nevertheless has potential in describing certain effects of PQQ.

With the above said, however, we would be remiss if did not also note that if PQQ has the potential of influencing probiotics. One has to also ask the question whether there is any impact on organisms, such as helicobacter pylori that has been associated with gastritis and gastric ulcers.  Only one study has been done that actually examines gut micro flora in the context of PQQ supplementation and its potential effects (Smidt et al., Does the intestinal microflora synthesize pyrroloquinoline quinone? Biofactors. 1991; 3:53-9). That study indicates that it is difficult to demonstrate PQQ synthesis by the microflora that are present in the gut.  Using a mouse as a model, there was also little change in the amounts of organisms that were reported to present in the intestine before versus after PQQ supplementation.

In summary, PQQ supplementation may be complementary to probiotic use, but more work needs to be done.  We also encourage you to read reviews that indicates the human body may respond differently to the different species and strains of probiotics (e.g., see Hakansson et al., Gut microbiota and inflammation. Nutrients. 2011; 3:637-82).

PQQ Salt vs PQQ

Does the chemical form of pyrroloquinoline quinone and PQQ salt make a difference for absorption or its biological effects?

Many people have noticed that supplement companies are selling products called PQQ but have PQQ salt listed in the ingredients, which is technically a different compound. So it is a thoughtful question to ask “Does the chemical form of PQQ make a difference?”  It is a great question and applies to many other compounds commonly found in supplements as well.  As usual, there is an important caveat, but the short answer is for the forms of PQQ currently used in supplements, there is probably little difference between the variability of nutritional availability (or relative potency if you will).

For example, the organic acid form of PQQ is quickly converted into a salt during the process of digestion (or merely dissolving PQQ into a complex mixture for that matter).  The H+ (from the organic acid moieties of pyrroloquinoline quinone) can exchange freely with ionized cations, such as sodium, potassium, magnesium.  Both the acid form and salt forms of PQQ, at the intestinal concentrations usually obtained following supplement use, are soluble and probably equally available (absorbable) by the intestine. Animal studies suggest that PQQ is reasonably well absorbed (>50 percent), particularly at low doses (Smidt et al. 1991 Intestinal absorption and tissue distribution of [14C] pyrroloquinoline quinone in mice. Proc Soc Exp Biol Med.197:27-31).

It is also worthy of note that ester forms of PQQ have also been studied.  Esters are formed when the organic acid moieties in targeted compounds are modified by linking them chemically to an alcohol (methyl, ethyl, or longer carbon-chained alcohol).  For pyrroloquinoline quinone, such modifications render or cause PQQ to become less-polar, i.e. less water soluble.  In general, these types of modifications are carried out to increase the solubility of the targeted compound in a lipid environment or improve its chemical stability.  With regard to digestion and absorption, a portion of the total amount of compound ingested might be absorbed into the body using one of the transport pathways designed for lipid compounds or, alternatively, be converted back to the original staring material by intestinal enzymes and then absorbed. Although there are no data regarding the absorption of PQQ esters, based on what is known about ascorbyl palmitate (an ester form of vitamin C) and tocopheryl acetate (an ester form of vitamin E), it may be assumed that at least a portion of a typical oral dose is absorbed.

PQQ in nature exists as free acid, as salts (e.g. the sodium salt of PQQ,) or as a complex derivative of an amino acid, imidazolopyrroloquinoline. The PQQ Ester is a product of chemical synthesis. All of the various forms are absorbed to some degree based on the fact physiological responses result from oral ingestion and supplementation.

So what is the caveat?  The most important caveat is that most of the PQQ consumed in the diet (even as a supplement) is immediately converted to even more complex derivatized forms than an ester or a salt.  PQQ reacts very rapidly with some amino acids, which are found in abundance in food or in the intestine (released because of protein digestion). When pyrroloquinoline quinone is added to aqueous suspensions of experimental diets, the recoveries of “free” PQQ becomes increasing lower in amount with a disappearance of “free” PQQ starting within minutes (Steinberg et al. 2003 PQQ improves growth and reproductive performance in mice fed chemically defined diets. Exp Biol Med (Maywood). 228:160-6).

PQQ also forms a compound called imidazolopyrroloquinoline or IPQ (Mitchell et al. 1999 Characterization of pyrroloquinoline quinone amino acid derivatives by electrospray ionization mass spectrometry and detection in human milk. Anal Biochem. 269:317-25). Although one can infer from the Smidt paper linked above that IPQ is absorbed, there are no data for humans or animals that addresses the question of nutritional availability with precision.  Right now all we know is that biological effects elicited by PQQ (either in “free” form or as the salt) are observed in animals and humans.

Is there a vitamin PQQ should be taken with?

Are there any other vitamin supplements that work well with PQQ?

As you are probably aware from reading PQQ, pyrroloquinoline quinone seems to act in promoting mitochondriogenesis and, in a broader context, by protecting neural tissue. Compounds that may promote mitochondriogenesis included resveratrol, quercetin, and hydroxytyrosol (found in olive oil). Other agents that promote mitochondrial function and performance may be synergistic. Such compounds include CoQ10 and carnitine. They either facilitate various metabolic events or aid in moving substrate into and out of the mitochondria. The point here is that just because both PQQ and CoQ10 are quinones, they are doing very different things. One would not want to substitute one for the other. Also, consider the following, consuming a traditionally well-balanced diet (with or without supplements) and regular aggressive exercise is also an excellent formula to stimulate mitochondriogenesis, particularly in muscle. Think of given supplements as a way to potentially optimize this process.

Does lipoic acid function synergistically with PQQ, vitamin C or other antioxidants?

Lipoic acid is a cofactor for one of the first steps in a major mitochondrial metabolic pathway. Ascorbic acid plays a number of cellular roles – only a few are specific to mitochondria. As chemicals, they work quite differently in the human body. There are a number of references that one can cite. The following is a good example. (Valdecantos et al. Vitamin C, resveratrol and lipoic acid actions on isolated rat liver mitochondria: all antioxidants but different. Redox Rep. 2010; 15:207-16).

What are some good antioxidants?

Many compounds are touted as better or worst regarding there antioxidant potential in chemical assays. In a recent paper, leaders in this field have pointed out that for many types of antioxidants, there effects are due to mechanisms that have little to do with their antioxidant potential (e.g., Hollman et al. The Biological Relevance of Direct Antioxidant Effects of Polyphenols for Cardiovascular Health in Humans Is Not Established. J Nutr. 2011 Mar 30). Although some compounds exert beneficial effects on some biomarkers of cardiovascular health, there is no evidence that this is caused by improvements in their antioxidant capacity. Rather, the real mechanisms have to do with cellular signaling, or the up- or down-regulation of complex metabolic pathways. To use, PQQ as an example, in chemical assays, it is easy to set conditions so that it may function as both a potent pro- and anti-oxidant. What pyrroloquinoline quinone can potentially do is stimulate mitochondriogenesis. The best way a cell has to coordinate oxidative and free radical potential is to optimize cellular organelles, such as mitochondria that are directly involved in oxidative metabolism.

Telomeres and Pyrroloquinoline Quinone

A telomere is a region of repetitive DNA at the end of a chromosome. Telomeres protect the ends of a given chromosome’s DNA from deterioration (although the shortening of chromosome telomeres normally occurs during chromosome replication). All cells that make up tissues undergo some degree of turnover (replication and apoptosis, i.e. programmed cell death). Cells are more easily destroyed when their telomeres are shortened, compromised, or defective. Some cells have ways, however, of evading normal programmed destruction and replacement. During replication, telomeres lose some of their genetic material but are repaired by an enzyme, telomerase. Some cancer cells maintain their telomeres and become so-called “immortalized” because of differences in telomere maintenance or the relative expression of telomerase levels.

Likewise, mitochondrial integrity is linked to apoptosis. There is little evidence, however, that directly links telomere integrity and telomerase activity to mitochondriogenesis or mitochondrial turnover. Telomere truncation and a reduction in cellular mitochondria, both contribute to apoptosis, but by separate, although coordinated by independent processes. Longer-lived cells often have more

With regard to PQQ, to the extent that pyrroloquinoline quinone can stimulate mitochondriogenesis, then one may speculate that PQQ may slow aging. If true, a likely mechanism is better control of maintaining reactive oxygen species (ROS), which can affect many aspects of cellular activity. Does PQQ affect telomere integrity? This question has not been specifically examined, but in one large gene array experiment using a rodent model (Biochem J. [2010] 429:515-26), no specific modulation of telomere-related proteins were detected. Mitochondria-related ROS modulation, however, might have an indirect

With regard to Coenzyme Q or ubiquinone, the primary effect is on the electron transport chain and aerobic cellular respiration. Ninety-five percent of the human body’s energy is generated this way and involves CoQ10. Tissues with high energy requirements usually have higher CoQ10 concentrations. It has been shown levels of CoQ10 seem to correlate with ROS production. Low dosages of CoQ10 reduce cellular ROS levels and DNA double-strand breaks (note – a different process than telomere maintenance). With this said, however, CoQ10 supplementation only has been associated with increased lifespan in mice or rats with very mixed results. The take-home message here is that for a defined response, if an organism has enough of a given substance taking more (of that substance) may not have an effect (and in some cases have an adverse adverse effect).

With regard to “feeling” better or worst in response to a supplement or change in a diet or activity – the answer is always a relative one. It is always important to ask – what are the thresholds that I am trying to achieve? If it is protection from disease or optimizing cellular maintenance, you may not know the answer until the end of life. Some times the best we can do is infer that the effects will be positive based on the scientific data available at the time.

PQQ Testimonials and Reviews

As pyrroloquinoline quinone gets more popular, it is interesting to hear what people are saying about this intriguing compound. If you would like to describe how PQQ has helped (or not helped) you, leave a comment below and we will add your thoughts to this pyrroloquinoline quinone testimonial page:

I recently started supplementing with PQQ and have noticed two profound effects. Firstly, a small white, slightly raised area on my lower lip which has been there since I was a teenager (I am now 59) completely disappeared within a week. I find this incredible. Secondly, there has been a significant improvement in my long vision. Previously I had difficulty seeing the letters and digits on car number plates more than three cars in front of me. In fact, at my last appointment with my ophthalmologist late last year I mentioned the deterioration in my sight and she checked my prescription and said it was fine. Now I can see number plates around 6 to 7 car lengths in front of me.

John E. – Sydney, Australia

I’m an amateur runner who has struggled for a long time to increase my my VO2 max and aerobic capacity. I have tried different means to make positive strides through both physical training plus changes and augmentation regarding nutrition, with mixed results. The two supplements where I feel like I have gotten the strongest benefit are methoxatin (PQQ) and alpha-lipoic acid. I have as tried rhodiola rosea with mixed results. The three helped in different ways but pyrroloquinoline quinone in isolation seemed to help with recovery allowing me to exert more effort during a subsequent workout, which in theory should help increase the efficiency of adaptation.

Mike R. – Berkeley, CA

I have been taking 20 mg of pyrroloquinoline quinone along with 300 mg of ubiquinol daily for about two months. As yet I have not noticed any effects, however I am age 82.

Doug G. – Maine

I supplemented my Parkinson’s regimen of Stalevo and Azilect with PQQ and soon felt an increase in nausea and off times.

Bob S.

I’ve been consuming pyrroloquinoline quinone along with resveratrol, carthinine and CoQ10. I’ve noticed increased stamina and a drop in blood pressure. It has also made me very calm. I am a 53 yrs old bodybuilder and can work out without getting tired.

Mike G. – Tampa Bay, FL

PQQ is amazing! I take 10 milligrams at 8am and also at noon. I benefit from improved mood, concentration, focus, stamina. even my complexion has improved.

Georgie – Virginia

Can one call pyrroloquinoline quinone, vitamin PQQ?

Does it make sense to call pyrroloquinoline quinone, vitamin PQQ? To make the case for the physiological and biomedical importance of PQQ, it is also important to appreciate that many of pyrroloquinoline quinone’s biological functions are universal.

Pyrroloquinoline quinone acts as growth factor to both plant and certain strains of bacteria.  PQQ is a trophic factor important to the growth and metabolism of methlyotropic bacteria (bacteria capable of growing on simple carbon sources).  Although a role as a vitamin-like cofactor has not been established in animals or plants, many bacteria utilize PQQ as an enzyme cofactor.  Enzymes containing PQQ are sometimes designated quinoproteins (proteins that contain biologically active quinone components).  Most of these enzymes act as dehydrogenases that modify a variety of sugars and alcohols in bacterial metabolic pathways. The PQQ-requiring quinoproteins/enzymes are distinguished, because the PQQ associated with these proteins is dissociable (loosely bound).

An important class of bacteria that interacts with plants is rhizobacterium (predominant bacterium in soil).  Rhizobacterium is one of several strains of bacteria that have developed pathways for synthesizing PQQ and now constitute a major environmental source. Plants cultivated with rhizobacterium have significantly increased height, flower number, fruit number and size.  This does not occur when genetically modified rhizobacteria unable to produce PQQ are added to cultures.  Of importance, PQQ added directly to the plants as an external nutrient or trophic factor also causes plants to flower and grow. Hence, it appears that PQQ in plants and bacteria can function as a growth-promoting agent.  Relatively small amounts of PQQ are needed to elicit given responses.  That PQQ is present in a wide variety of foods (see PQQ Rich Foods) is due in large part to its function and presence in plants and fermented (bacterially derived products).   Similar to other compounds that have physiological functions and applications in animals, PQQ is ubiquitous and appears utilized by a wide variety of organisms.