Notifications
Clear all

Pyrroloquinoline Quinone Inhibits Lactate Dehydrogenase

12 Posts
4 Users
22 Likes
172 Views
medline
(@aliml2)
Joined: 9 months ago
Posts: 124
Topic starter  

Abstract

Pyrroloquinoline quinone (PQQ), a redox-active o-quinone, is an important nutrient involved in numerous physiological and biochemical processes in mammals. Despite such beneficial functions, the underlying molecular mechanisms remain to be established. In the present study, using PQQ-immobilized Sepharose beads as a probe, we examined the presence of protein(s) that are capable of binding PQQ in mouse NIH/3T3 fibroblasts and identified five cellular proteins, including l-lactate dehydrogenase (LDH) A chain, as potential mammalian PQQ-binding proteins. In vitro studies using a purified rabbit muscle LDH show that PQQ inhibits the formation of lactate from pyruvate in the presence of NADH (forward reaction), whereas it enhances the conversion of lactate to pyruvate in the presence of NAD+ (reverse reaction). The molecular mechanism underlying PQQ-mediated regulation of LDH activity is attributed to the oxidation of NADH to NAD+ by PQQ. Indeed, the PQQ-bound LDH oxidizes NADH, generating NAD+, and significantly catalyzes the conversion of lactate to pyruvate. Furthermore, PQQ attenuates cellular lactate release and increases intracellular ATP levels in the NIH/3T3 fibroblasts. Our results suggest that PQQ, modulating LDH activity to facilitate pyruvate formation through its redox-cycling activity, may be involved in the enhanced energy production via mitochondrial TCA cycle and oxidative phosphorylation.

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4882622

Pyrroloquinoline quinone (PQQ) at a concentration of 100 micromolar reduces lactate production to zero, which according to my calculations, is equivalent to a dose of 160 mg!


   
Daniel, johan, dng050 and 3 people reacted
Quote
dng050
(@dng050)
Joined: 3 years ago
Posts: 54
 

@aliml2 Very interesting, we have been looking for a way to reduce LDH in lung cancer without using any drugs. Have started R-Lipoic Acid, and will take a look at PQQ.


   
medline, johan, medline and 1 people reacted
ReplyQuote
johan
(@j)
Joined: 4 years ago
Posts: 1196
 
Posted by: @dng050

@aliml2 Very interesting, we have been looking for a way to reduce LDH in lung cancer without using any drugs. Have started R-Lipoic Acid, and will take a look at PQQ.

I hope your brother is well.

Effects of Salvia miltiorrhiza extract on lung adenocarcinoma

https://www.spandidos-publications.com/10.3892/etm.2021.10226

Possible synergy with baicalein.


   
medline and medline reacted
ReplyQuote
medline
(@aliml2)
Joined: 9 months ago
Posts: 124
Topic starter  
Posted by: @dng050

we have been looking for a way to reduce LDH in lung cancer without using any drugs. Have started R-Lipoic Acid, and will take a look at PQQ.

If PQQ were available in injectable form, concentrations of 100 μM would be easily obtained, but the bioavailability of the oral form is unknown.

In addition to R-Lipoic acid, thiamine, magnesium, melatonin, and creatine also reduce serum lactate levels. I don't know if this decrease in serum lactate is due to inhibition of LDH or activation of pyruvate dehydrogenase complex.

Decreased activity of pyruvate dehydrogenase complex causes lactic acidosis, and vitamins B1, B2, B3, B5, magnesium, and lipoic acid are also its cofactors.

Lactate dehydrogenase (LDH) inhibitors:
Converts Pyruvate to Lactate.

– LDH consists of LDHA and LDHB subuinits, which can assemble into five different combinations (LDH1 is comprised of four LDHB subunits; LDH2 contains three LDHB and one LDHA subunit; LDH3 contains two LDHB and two LDHA subunits; LDH4 contains one LDHB and three LDHA subunits; and LDH5 contains four LDHA subunits)
– LDH5 isoenzyme present on cancer cells converts pyruvate to lactate, whereas the LDH1 isoenzyme is present on cells that can import lactate and convert it to pyruvate (Ref.)

  • Diclofenac – inhibits GLUT1, LDHA and MCT1  (Ref.) – FDA approved drug used as anti pain medication – over the counter drug
  • Machilin A – the strongest inhibitor on enzymatic activity of LDHA among 480 compounds in a natural product library. MA inhibited the LDHA activity through the suppression of an NADH cofactor binding to lactate dehydrogenase (Ref.). Can be found in Myristica fragrans (fragrant nutmeg or true nutmeg), a dark-leaved evergreen tree (Ref.) which can be found online as Nutmeg.
  • Epigallocatechin from green tea (Ref.1, Ref.2, Ref.3)
  • Oxamate (Ref.1, Ref.2) – Not available.
  • Gossypol (also known as AT-101), a cotton seed extract, is a nonselective inhibitor of LDH (LDHA and LDHB) that blocks the binding of NADH (Ref.). Not easily available.
  • Galloflavin inhibits both LDH (LDHA and LDHB) isoforms (Ref.) Not easily available.
  • Stiripentol – inhibits LDH1 and LDH5 (Ref.) – an anticonvulsant FDA approved drug (Ref.)
  • Crocetin – inhibits LDH5 (Ref.) – the compound responsible for the color of saffron
  • Vitamin C – inhibits LDHA (Ref.) – supplement available online – inhibits LDHA expression in response to stress (Ref.)
  • Propranolol – and FDA approved drug that may inhibit stress-induced LDHA expression (Ref.) – previously discussed here (Ref.)

As a side note, here is a recent article connecting chronic stress with LDHA activation and breast cancer (Ref.) Chronic stress increases epinephrine levels and activates β2-adrenergic receptor to in turn induce expression of LDHA , inducing cancer stem-like phenotype. LDH inhibitors can revers that (Ref.). This is one example how Green tea and Vitamin C can reduce chance of cancer as a result of chronic stress.

https://cancertreatmentsresearch.com/drugs-and-supplements-that-block-fermentation-and-help-fight-cancer

Sympathetic stimulation increases serum lactate concentration, but β-blocker decrease lactate. Sleeping on the right side is one of the ways to reduce sympathetic activity, but sleeping on the left side increases pulmonary vein stress.

Interestingly, LDH inhibition decreases oxalate levels, but both oxalate and its derivative, oxamate, are LDH inhibitors!

A question that may arise is whether an oxalate-rich diet lowers LDH?


   
ReplyQuote
dng050
(@dng050)
Joined: 3 years ago
Posts: 54
 

@j Hi, Johan. He is stable for the moment on a TKI, but there are some troubling blood work, such as elevated LDH (230) and platelets (320). 


   
ReplyQuote
medline
(@aliml2)
Joined: 9 months ago
Posts: 124
Topic starter  

INACTIVATION OF LACTATE DEHYDROGENASE BY SEVERAL CHEMICALS: IMPLICATIONS FOR IN VITRO TOXICOLOGY STUDIES

Abstract

Lactate dehydrogenase (LDH) release is frequently used as an end-point for cytotoxicity studies. We have been unable to measure LDH release during studies using para-aminophenol (PAP) in LLC-PK1 cells. When LLC-PK1 cells were incubated with either PAP (0–10 mM) or menadione (0–1000 μM), viability was markedly reduced when assessed by alamar Blue or total LDH activity but not by release of LDH into the incubation medium. In addition, we incubated cells with PAP or menadione and compared LDH activity using two different assays. Both assays confirmed our observation of decreased LDH activity in cell lysates without corresponding increases in LDH activity in incubation media. Using purified LDH and 10 mM PAP, we that PAP produced loss of LDH activity that was inversely proportional to the amount of LDH initially added. In additional experiments, we incubated 0.5 units of LDH for 1 h with varying concentrations of PAP, menadione, hydrogen peroxide (H2O2) or cisplatin. All four chemicals produced concentration-dependent decreases in LDH activity. In previous experiments, inclusion of antioxidants such as reduced glutathione (GSH) and ascorbate protected cells from PAP toxicity. GSH (1 mM) preserved LDH activity in the presence of toxicants while ascorbate (1 mM) only prevented LDH loss induced by PAP. These studies suggest that LDH that is released into the incubation medium is susceptible to degradation when reactive chemicals are present.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1861824

Menadione (Vitamin K3), which is a quinone like PQQ, decreases LDH activity. Interestingly, addition of ascorbate to menadione further decreased LDH activity, but addition of glutathione (GSH) again increased LDH activity!

Cancer cells rely mainly on glutathione (high GSH/GSSG ratio) to protect themselves from apoptosis and maintain a growth-promoting environment.

Other quinones such as CoQ10, Emodin, Lapachone, Thymoquinone, etc. also appear to have the ability to reduce serum lactate.


   
johan and johan reacted
ReplyQuote
johan
(@j)
Joined: 4 years ago
Posts: 1196
 
Posted by: @dng050

@j Hi, Johan. He is stable for the moment on a TKI, but there are some troubling blood work, such as elevated LDH (230) and platelets (320). 

Something to watch closely indeed. You mentioned lipoic acid and medline has listed many other good options, one other I would like to bring to your attention is copper, I am aware copper chelation can be beneficial in cancer but too little copper could also be a bad thing.

https://www.semanticscholar.org/paper/Effects-of-copper-on-CHO-cells%3A-Cellular-and-Yuk-Russell/55cf93cb7bd03235a80b62e921ad4656d66af737


   
ReplyQuote
dng050
(@dng050)
Joined: 3 years ago
Posts: 54
 

From the abstract of the article referred by @aliml2:

"Our results suggest that PQQ, modulating LDH activity to facilitate pyruvate formation through its redox-cycling activity, may be involved in the enhanced energy production via mitochondrial TCA cycle and oxidative phosphorylation." (My emphasis)

Does this mean that PQQ might push cancer towards OXPHOS? In that case, we might as well consider something to address OXPHOS. 

 

   
ReplyQuote
Daniel
(@daniel)
Admin
Joined: 7 years ago
Posts: 1156
 
Posted by: @aliml2

Abstract

Pyrroloquinoline quinone (PQQ), a redox-active o-quinone, is an important nutrient involved in numerous physiological and biochemical processes in mammals. Despite such beneficial functions, the underlying molecular mechanisms remain to be established. In the present study, using PQQ-immobilized Sepharose beads as a probe, we examined the presence of protein(s) that are capable of binding PQQ in mouse NIH/3T3 fibroblasts and identified five cellular proteins, including l-lactate dehydrogenase (LDH) A chain, as potential mammalian PQQ-binding proteins. In vitro studies using a purified rabbit muscle LDH show that PQQ inhibits the formation of lactate from pyruvate in the presence of NADH (forward reaction), whereas it enhances the conversion of lactate to pyruvate in the presence of NAD+ (reverse reaction). The molecular mechanism underlying PQQ-mediated regulation of LDH activity is attributed to the oxidation of NADH to NAD+ by PQQ. Indeed, the PQQ-bound LDH oxidizes NADH, generating NAD+, and significantly catalyzes the conversion of lactate to pyruvate. Furthermore, PQQ attenuates cellular lactate release and increases intracellular ATP levels in the NIH/3T3 fibroblasts. Our results suggest that PQQ, modulating LDH activity to facilitate pyruvate formation through its redox-cycling activity, may be involved in the enhanced energy production via mitochondrial TCA cycle and oxidative phosphorylation.

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4882622

Pyrroloquinoline quinone (PQQ) at a concentration of 100 micromolar reduces lactate production to zero, which according to my calculations, is equivalent to a dose of 160 mg!

Thank you for sharing, Very interesting. Could you please share your calculations indicating that 160mg woudl be enough if given IV? What was the exposure time required in the study for the inactivation of glyco?


   
medline and medline reacted
ReplyQuote
Daniel
(@daniel)
Admin
Joined: 7 years ago
Posts: 1156
 
Posted by: @aliml2

INACTIVATION OF LACTATE DEHYDROGENASE BY SEVERAL CHEMICALS: IMPLICATIONS FOR IN VITRO TOXICOLOGY STUDIES

Abstract

Lactate dehydrogenase (LDH) release is frequently used as an end-point for cytotoxicity studies. We have been unable to measure LDH release during studies using para-aminophenol (PAP) in LLC-PK1 cells. When LLC-PK1 cells were incubated with either PAP (0–10 mM) or menadione (0–1000 μM), viability was markedly reduced when assessed by alamar Blue or total LDH activity but not by release of LDH into the incubation medium. In addition, we incubated cells with PAP or menadione and compared LDH activity using two different assays. Both assays confirmed our observation of decreased LDH activity in cell lysates without corresponding increases in LDH activity in incubation media. Using purified LDH and 10 mM PAP, we that PAP produced loss of LDH activity that was inversely proportional to the amount of LDH initially added. In additional experiments, we incubated 0.5 units of LDH for 1 h with varying concentrations of PAP, menadione, hydrogen peroxide (H2O2) or cisplatin. All four chemicals produced concentration-dependent decreases in LDH activity. In previous experiments, inclusion of antioxidants such as reduced glutathione (GSH) and ascorbate protected cells from PAP toxicity. GSH (1 mM) preserved LDH activity in the presence of toxicants while ascorbate (1 mM) only prevented LDH loss induced by PAP. These studies suggest that LDH that is released into the incubation medium is susceptible to degradation when reactive chemicals are present.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1861824

Menadione (Vitamin K3), which is a quinone like PQQ, decreases LDH activity. Interestingly, addition of ascorbate to menadione further decreased LDH activity, but addition of glutathione (GSH) again increased LDH activity!

Cancer cells rely mainly on glutathione (high GSH/GSSG ratio) to protect themselves from apoptosis and maintain a growth-promoting environment.

Other quinones such as CoQ10, Emodin, Lapachone, Thymoquinone, etc. also appear to have the ability to reduce serum lactate.

Interesting indeed. Many ideas for experiments come to mind. 

For example, woudl supporting mitochondria activity lead to increase in ROS and as a result higher demand of glutathione? In that case, it makes sense LDH activity (and glyco in general) woudl decrease and PPP pathway activity woudl increase to provide fuel for anti-oxidant production. On the other hand, adding glutathione woudl release the ROS pressure and glycolysis woudl increase to support other mechanisms.

So it woudl be interesting to look at what happens with PPP when some of those you mentioned woudl be used, and what woudl happen when PPP woudl be blocked at the same time.


   
ReplyQuote
medline
(@aliml2)
Joined: 9 months ago
Posts: 124
Topic starter  

@dng050
OXPHOS deficiency characteristic of all cancer cells, and restoration of OXPHOS is highly therapeutic by Quinone molecules. Cancer cells have, in fact, higher respiration rats than normal cells, however the mitochondria of cancer cells consume rather than produce ATP. The source of that ATP is likely the upregulated glycolysis (Warburg Effect), which is another hallmark of all cancer cells. So, in a sense, cancer cells have a very high rate of futile metabolism and they consume ATP in order to grow and multiply, instead of contributing to the healthy (OXPHOS vs. glycolysis) process of producing energy.

@daniel
I did the calculations as follows:

PQQ molar mass: 330.206 g/mol (I googled it!)
∴ 1 mol of PQQ = 330.206 g

1 molar = 1,000,000 micromolar
∴ 1 μM of PQQ = 0.000330206 g (330.206 ÷ 1000000)
∴ 100 μM of PQQ = 0.0330206 g (100 x 0.000330206)

So we need 0.0330206 g of PQQ per liter of blood.

An average adult has nearly 5 liters of circulating blood.
∴ 5 x 0.0330206 = 0.165103 g

We know that 1 g = 1000 mg and we need 0.165103 g of PQQ.
∴ 0.165103 x 1000 = 165.103 mg

So injecting 165 mg of PQQ would give us a concentration of 100 µM, and one hour after the injection, we should see a decrease in LDH activity and as a result a decrease in Lactate/Pyruvate and NADH/NAD+ ratios.

Given that the increase in OXPHOS causes the consumption of GSH, it can be expected that the ratio of GSH/GSSG will also decrease. GSH-depleting agents make cancer cells more vulnerable to ROS and thus to apoptosis.

All the above ratios increase in cancer patients.

But for the oral form of PQQ, higher doses are needed, perhaps combining it with vitamin C will reduce the required dose, such as the combination of menadione and ascorbate. 

Treatment with 400mg of CoQ10 significantly reduced serum concentrations of lactate, pyruvate, MMP-9 and NO while CoQ10 concentrations increased after 12 weeks (p < 0.05). There was a significant reduction in lactate/pyruvate ratio in intervention group. None of these changes had been observed in placebo treated group (p > 0.05).

https://sciencedirect.com/science/article/abs/pii/S1876382018303767

In general, quinones pair well with ascorbic acid!


   
Daniel, johan, Daniel and 1 people reacted
ReplyQuote
Daniel
(@daniel)
Admin
Joined: 7 years ago
Posts: 1156
 

@aliml2 Thank you for the quality response! Very much appreciated! 👍 


   
medline and medline reacted
ReplyQuote
Share: