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Molnupiravir Against COVID-19

Molnupiravir is an antiviral drug that has recently been approved by the FDA for the treatment of COVID-19. This drug is especially exciting because it is the first approved COVID-19 drug that can be taken as a pill, and also because it reduces the risk of hospitalization and death by 30%. Two recent research papers give us insight into the molecular biology of how molnupiravir works.

In order to reproduce, the virus SARS-CoV-2 needs to synthesize RNA. Usually, the enzyme it uses to do this, RNA-dependent RNA polymerase (RdRp), is an attractive target for makers of antiviral drugs. At present, many antiviral drugs block RdRp by mimicking RNA nucleotides. When such a drug gets incorporated into a new RNA strand, synthesis stops. Unfortunately, this drug strategy is not effective against SARS-CoV-2 because it has proofreading enzymes that allow synthesis to continue.

Two research teams in Germany and Canada recently showed that molnupiravir mimics cytidine and uridine, two RNA nucleotides. Molnupiravir incorporates into new RNA strands, like other antiviral drugs. But interestingly, RdRp continues to synthesize RNA. How, then, does molnupiravir prevent severe COVID-19?

Both teams addressed this question by combining RNA that contained molnupiravir with RdRp in vitro. They found that when RdRp uses this RNA to synthesize new RNA, molnupiravir causes mutations. After several generations, mutations build up to a lethal level and the virus can no longer reproduce.

Molnupiravir’s mechanism of action evades viral proofreading enzymes. Because of this, it may also find use in treating a broad variety of other viruses that also have these enzymes.

 

Kabinger F, Stiller C, Schmitzova J, et al. Mechanism of molnupiravir-induced SARS-CoV-2 mutagenesis. Nature Structural & Molecular Biology. 2021 Sep;28(9):740-746. PMID: 34381216

Gordon CJ, Tchesnokov EP, Schinazi RF, et al. Molnupiravir promotes SARS-CoV-2 mutagenesis via the RNA template. Journal of Biological Chemistry. 2021 Jul;297(1):100770. PMID: 33989635

FDA News Release: FDA authorizes additional oral antiviral for treatment of COVID-19 in certain adults

Fidaxomicin as a New Antibiotic Template

Fidaxomicin is a narrow-spectrum antibiotic that is specific against gram-positive bacteria. Furthermore, it is not well absorbed into the bloodstream, so it remains in the gut. Both these characteristics make it a useful drug to treat Clostridioides difficile infections. It has been in clinical use since 2011.

Fidaxomicin-resistant C. difficile is currently rare, but antibiotic resistance is always a concern. A team of scientists at the University of Zurich, Switzerland wanted to use fidaxomicin as a template to develop new antibiotics before more resistant strains evolve.

They used a rational design approach, starting with the cryo-EM structure of fidaxomicin bound to bacterial RNA polymerase. Fidaxomicin has two carbohydrates attached to it, a noviose and a rhamnose. Based on the cryo-EM structure, the C3″ on the noviose looked like a promising place to add new functional groups. The team made thirty derivatives of fidaxomicin by changing the functional groups on that carbon.

They tested the antibiotic activity of these derivatives by measuring their minimal inhibitory concentration against C. difficile. Many of the derivatives still showed antibiotic activity. Although the derivatives were not any more effective against C. difficile than fidaxomicin, this experiment is an encouraging proof of concept for the rational design of new antibiotics.

 

Dailler D, Dorst A, Schafle D, et al. Novel fidaxomicin antibiotics through site-selective catalysis. Communications Chemistry. 2021. 4:59.  doi.org/10.1038/s42004-021-00501-6.

Astaxanthin Antitumor Effect

Astaxanthin is a natural pigment that makes many sea creatures red, such as shrimp and crabs. It has many commercial uses such as a food coloring and an animal feed supplement, and it is an antioxidant. Previous research has found that astaxanthin has an antitumor effect.

Glioblastoma is a type of brain cancer with an especially poor prognosis. It is difficult to treat because most cancer drugs can’t cross the blood-brain barrier to reach the brain tumor. Some natural products such as curcumin can cross the blood-brain barrier. Recently, a team of scientists in Japan set out to test whether astaxanthin can cross the blood-brain barrier and whether it can act against glioblastoma tumors.

First, the researchers added astaxanthin to a cell culture line of mouse glioblastoma cells. They found that the cells had reduced proliferation and migration, both of which are needed for tumors to spread.

Then they fed astaxanthin to mice and were able to detect it in mouse brains, suggesting that astaxnthin can cross the blood-brain barrier. The researchers fed astaxanthin to mice with a model of glioblastoma and the tumor growth was notably inhibited.

Astaxanthin may inhibit glioblastoma growth because it is an antioxidant. Antioxidants can affect the cell signals that control growth and division. The antitumor effect of astaxanthin in this experiment was modest, but astaxanthin is worth researching in combination with other promising glioblastoma drugs.

 

Tsuji S, Nakamura S, Maoka T, et al. Antitumor effects of astaxanthin and adonixanthin on glioblastoma. Marine Drugs. 2020 Sep 18;18(9):474. doi:10.3390/md18090474. PMID: 32962073.

Protease Inhibitors: Saquinavir and Boceprevir

The COVID-19 pandemic continues to cause death and severe illness around the world. As many countries still experience vaccine shortages and the virus evolves to be more contagious, we need to develop better treatments for this disease.

A Possible Target:

The SARS-CoV2 main protease (Mpro) is an attractive target for drug treatment. The coronavirus needs this protease to process its proteins, an important step in its life cycle. Protease inhibitors are already in clinical use to treat other viral infections, such as HIV and hepatitis C. Repurposed existing drugs can get approval to treat disease faster than new drugs because their safety and pharmacokinetics are already known. Can we repurpose known protease inhibitors to treat SARS-CoV2 infection?

Two recent scientific studies address this question.

Docking and Molecular Dynamics Simulations:

Bello et al. built a computer model of Mpro and twelve promising protease inhibitors: darunavir, indinavir, saquinavir, tipranavir, diosmin, hesperidin, rutin, raltegravir, velpatasvir, ledipasvir, rosuvastatin, and bortezomib. The model predicts that of the twelve, saquinavir should bind to Mpro the best. Interestingly, saquinavir has long been used as part of drug cocktails to treat HIV. Although a computer study is limited, saquinavir is worth following up in vitro.

Enzyme Assays:

Another team of researchers, Ma et al., used an enzyme assay to screen for drugs that might inhibit the activity of Mpro. Out of a library of known inhibitors, they found that boceprevir inhibited Mpro the most. Formerly, boceprevir was used to treat hepatitis C before more effective protease inhibitors were developed. Boceprevir might find new life now as a treatment for COVID-19, and is worth further study.

 

Bello M, Martinez-Muñoz A, Balbuena-Rebolledo I. Identification of saquinavir as a potent inhibitor of dimeric SARS-CoV2 main protease through MM/GBSA. Journal of Molecular Modeling. 2020 Nov 12; 26(12):340. PMID: 33184722

Ma C, Sacco MC, Hurst B, et al. Boceprevir, GC-376, and calpain inhibitors II, XII inhibit SARS-CoV2 viral replication by targeting the viral main protease. Cell Research. 2020 Aug; 30(8):678-692. PMID: 32541865

Remdesivir Synergy Against COVID-19

Currently, remdesivir is the only antiviral drug approved to treat COVID-19. Its effects on the course of disease are moderate. Many viral diseases, such as HIV and hepatitis C, are treated with drug cocktails. Existing antiviral drugs might make remdesivir more effective in combination.

Two research teams recently screened for antiviral drugs that might increase the effectiveness of remdesivir.

Lo et al. screened a library of drugs for its ability to reduce SARS-CoV-2 viral load in kidney epithelial cells. They found that simeprevir reduces viral load in vitro. Simeprevir is a protease inhibitor that is often combined with sofosbuvir to treat hepatitis C. Simeprevir was even more effective in the in vitro experiment when combined with remdesivir.

Nguyenla et al. added remdesivir to cell cultures of kidney epithelial cells and human lung cells and infected these cells with SARS-CoV-2. They used this remdesivir-treated culture to screen a large library of FDA-approved drugs for compounds that reduce a proxy measure of viral load. The team chose the twenty most promising drugs to validate in human lung cell culture, which they tested for viral load.

The drugs velpatasvir and elbasvir reduced viral load. Both velpatasvir and elbasvir are used as parts of drug cocktails to treat hepatitis C. Velpatasvir is used with sofosbuvir and elbasvir is used with grazoprevir. The research team then tested the velpatasvir/sofosbuvir and elbasvir/grazoprevir cocktails with remdesivir in lung cell culture; the three-drug cocktails were even more effective that the pairs.

These results support the idea that COVID-19 could be better treated with cocktails of antiviral drugs.

 

Lo HS, Hui KPY, Lai HM, et al. Simeprevir potently suppresses SARS-CoV-2 replication and synergizes with remdesivir. ACS Central Science. 2021 May 26;7(5): 792-802. doi: 10.1021/acscentsci.0c01186. PMID: 34075346

Nguyenla X, Wehri E, Dis EV, et al. Discovery of SARS-CoV-2 antiviral synergy between remdesivir and approved drugs in human lung cells. BiorXiv. Preprint. 2020 Sept. http://doi.org/10.1101/2020.09.18.302398

Baloxavir Antiviral to Shorten and Prevent Influenza

Baloxavir is an antiviral drug that was FDA approved in 2018 for the treatment of influenza. It works by inhibiting an enzyme that influenza needs to replicate its DNA. When taken early, it can shorten the course of influenza by a day.

But can it also prevent influenza?

Researchers working for Shionogi, the manufacturer of baloxavir, set up a clinical trial in Japan to test this question. During the 2018-2019 flu season, they identified patients with influenza when they went to see their primary care doctor.

The researchers offered the household contacts of these patients either baloxavir or a placebo. Ten days later, the researchers tested the household contacts for influenza RNA (clinical influenza) using RT-PCR.

1.9% of household contacts who took the active treatment had clinical influenza whereas 13.6% of household contacts who took the placebo had clinical influenza. This is a successful demonstration that Baloxavir is effective at preventing influenza and as such was recently FDA approved for this use.

The authors of this study were not able to rule out whether this chemical can contribute to the rise of drug-resistant influenza. Further research is needed on this topic.

 

Baloxavir

Baloxavir Marboxil

 

Ikematsu H, Hayden FG, Kawaguchi K, et al. Baloxavir marboxil for prophylaxis against influenza in household contacts. N Engl J Med. 2020 Jul 23; 383(4):309-320. doi 10.1056/NEJMoa1915341. PMID: 32640124.

 

Rosiglitazone for Neuroinflammatory Abnormalities

Gulf War Illness is a chronic disorder brought on by exposure to sand storms, prophylaxis against chemical warfare, and chronic unpredictable stress. This illness is characterized by neuropsychological and cognitive problems affecting the central nervous system as well as specific organs.

Animal studies of this illness have shown neuroinflammation in several regions of the brain. Treatments used to reduce the neuroinflammation have led to improvements of the neurofunctional abnormalities.

Rosiglitazone and pioglitazone are compounds from the thiazolidinedione family that both have demonstrated neuroprotection in animal models. A new study recently completed at the University of Maryland looked at Gulf War Illness in a rat model and the impact of treatment with rosiglitazone.

Simulation

In order to simulate a Gulf War type of exposure, the rats were subjected to a variety of intense daily stressors for 33 days. Stressors included subjection to restraint, cold, wet, hunger, thirst, and various other types of unpredictably timed environmental stresses. During the 33 days the experimental treatment groups were also administered an oral solution of rosiglitazone each day.

Live Testing

Beginning on day 35, a battery of neurofunctional evaluations was begun. Evaluations included open-field exploration, maze exploration, new object recognition, sucrose preferences, tail suspension response, coat hygiene, splash testing, and forced swimming. These test methods were used as a gauge for cognition, anxiety-like behavior, and depression-like behavior.

Neurofunctional evaluation of the groups showed the development of significant abnormalities in rats exposed to the stressors compared to rats not subjected to such stress. The results of rats exposed to daily stressors and treatment with rosiglitazone were less conclusive. Rosiglitazone treatment seemed to improve measures related to cognition and anxiety, while not having much impact on weight gain or depression.

Tissue Testing

Following the neurofunctional evaluations, the rats were sacrificed so that the brain tissues could be analyzed. Examination of astrocytes, translocator protein, and microglia showed results consistent with a reduced inflammatory response in the samples from the rosiglitazone-treated group.

This modelling of Gulf War Illness successfully induced critical neurofunctional abnormalities, while the concurrent treatment with rosiglitazone reduced the development or abnormalities and neuroinflammation. The model will be useful for further study of the impact and potential treatments for Gulf War Illness.

 

Learn more about Gulf War Illness on Wikipedia

 

Thiazolidinediones Available:

Ciglitazone

Pioglitazone

Rosiglitazone

Rosiglitazone Maleate

Troglitazone

 

Keledjian K, Tsymbalyuk O, Semick S, et al. The peroxisome proliferator-activated receptor gamma (PPARγ) agonist, rosiglitazone, ameliorates neurofunctional and neuroinflammatory abnormalities in a rat model of Gulf War Illness. PLoS One. 2020 Nov 13;15(11):e0242427. PMID: 33186383

Lovastatin Impact on Brain Cholesterol

Lovastatin’s impact on brain cholesterol levels is found to produce neuroprotective effects.

Statins are known to reduce cholesterol synthesis in the liver, easily cross the blood-brain barrier, and have various additional effects on brain cells.

Lovastatin, aka Mevinolin, is commonly used as a medication to slow the production of cholesterol in the body, leading to reduced concentration of cholesterol in the blood, and thereby preventing buildup on artery walls.

Interestingly, in the average healthy adult, 25% of total cholesterol is in the brain.

This cholesterol in the brain is necessary to maintain the nicotinic acetylcholine receptors (nAChRs) at the cell membranes and for moving ions across the membranes.

There are different kinds of nAChRs present in the central nervous system, with both homomeric and dimeric species. The most abundant of the homomeric species in the central nervous system is α7 nAChR, while the most abundant dimeric species is the combination of α4 and β2 subunits.

These nAChR species play roles in a variety of cognitive functions, including learning, memory, and involvement in the development of Alzheimer’s disease. At the same time, the nAChRs all seem to be quite sensitive to membrane cholesterol levels. As has been demonstrated, the levels of nAChRs may be altered by manipulating the cholesterol level.

Cholesterol is known to have a big impact on muscle-type nAChR, however, its impact on neuronal-type nAChR is less studied.

Consequently, a study was formed to evaluate the impact of ongoing lovastatin treatment on cholesterol levels and the α7 and α4-containing nAChRs.

When cultured hippocampal neurons were incubated with varying levels of lovastatin for up to 14 days the total and surface cholesterol levels were significantly reduced, in a dose-dependent manner. No signs of neuronal damage were observed at the concentrations used, 0, 10, 50, 100, and 1000 nM.

The levels of α7 nAChR found in the cultured hippocampal nerves were monitored and found to be increased with the lovastatin treatments.

Previous studies have suggested that individuals with long-term statin treatment are less susceptible to developing Alzheimer’s disease. The nAChR species in the central nervous system are potentially a key to this phenomenon.

The lingering question remains: is it the impact on cholesterol biosynthesis, which occurs in the liver, and the resulting decreased level of cholesterol interacting with the nAChRs in the brain, or is it the statin itself entering the brain, that is responsible for the neuroprotective effect? It is quite possibly a combination of both factors and more research may be able to tease this information apart.

 

Additional Statins Available…

 

Borroni V, Kamerbeek C, Pediconi M, et al. Lovastatin differentially regulates α7 and α4 neuronal nicotinic acetylcholine receptor levels in rat hippocampal neurons. Molecules. 2020 Oct 20;25(20):4838. doi: 10.3390/molecules25204838. PMID: 33092257.

https://www.scientificamerican.com/article/this-is-your-brain-on-cholesterol/

 

Vinca Alkaloids and Their Biosynthesis Enzymes

Vinca alkaloids such as vincristine and vinblastine are crucial for the treatment of several types of cancers. However, these drugs are also in short supply, because they can only be found in small amounts in one plant species, the Madagascar periwinkle.

Unfortunately, the biosynthetic pathway that the Madagascar periwinkle uses to produce vincristine and vinblastine isn’t yet fully understood. However, if we find a way to manipulate that pathway, then we may be able to upregulate production of these molecules or transfer the pathway into another plant species that is easier to grow. Recently, a team of researchers identified the last two enzymes in the vinblastine biosynthesis pathway.

To begin, this team searched periwinkle RNA expression data for genes that are expressed at the same time as known vinblastine synthesis enzymes. Consequently, they found two candidate genes, which they named taberosine synthase (TS) and catharanthine synthase (CS). They first tried knocking out the genes’ expression in periwinkle plants. As a result, plants without TS and CS expression made much less precursors to vinblastine.

Next, they expressed TS and CS in the leaves of tobacco plants. Under these circumstances, the leaves formed detectable levels of vinblastine precursors.

Conceivably, these enzymes could be used to produce vinblastine and other medically important vinca alkaloids in other plant species.

 

 

Caputi L, Franke J, Farrow SC, et al. Missing enzymes in the biosynthesis of the anticancer drug vinblastine in Madagascar periwinkle. Science. 2018 Jun 15;360(6394):1235-1239. PMID: 29724909

Lopinavir Antiretroviral Delivery Using NLC

Lopinavir is an antiretroviral drug that is important for the treatment of HIV. Unfortunately, it has a low bioavailability because it dissolves poorly in water.

The drug might be absorbed better if it was encased in a nanostructured lipid carrier (NLC). An NLC is a particle containing a mixture of solid and liquid lipids- which should deliver drugs better than solid-only lipid particles. Recently, researchers in Malaysia sought to do a proof-of-concept of an NLC to deliver lopinavir.

To determine optimal conditions for creating NLCs, they varied homogenization time and amounts of solid lipid, liquid lipid, and surfactant. They picked the most promising sets of conditions for further study.

The researchers tested the NLCs for drug release rate in simulated gastric fluid and in simulated intestinal fluid. The NLCs released drug better than straight lopinavir, which would not dissolve in either fluid. Next, they applied the NLCs to a cell line that is popular for studying intestinal epithelium. NLC lopinavir entered the cells faster than straight lopinavir.

Finally, the researchers fed an NLC lopinavir suspension to rats. The rats reached higher blood lopinavir concentrations than rats fed straight lopinavir.

Lopinavir is an antiretroviral drug with poor bioavailability. Nanostructured lipid carriers show potential for improved drug delivery of lopinavir.

Khan AA, Mudassir J, Akhtar S, et al. Freeze-dried lopinavir-loaded nanostructured lipid carriers for enhanced cellular uptake and bioavailability: statistical optimization, in vitro and in vivo evaluations. Pharmaceutics. 2019; 11(2):97. PMID: 30823545

Baricitinib: Inhibitor of JAK-STAT Pathway

Baricitinib inhibits Janus kinases 1 and 2. These kinases are the first enzymes of the JAK-STAT signaling pathway. This pathway is important for many cell functions. Disorders of JAK-STAT can play a role in cancer and immune disease. For example, baricitinib, a JAK-STAT signaling disrupter, is approved in Europe to treat rheumatoid arthritis.

Progeria and JAK-STAT

Recently, researchers at the Technical University of Munich using a text mining approach had suspicions that a rare premature aging disorder, Hutchinson-Gilford progeria syndrome, is associated with the JAK-STAT pathway. It is known that this syndrome has four main symptoms that mimic normal aging: vascular disease, arthritis, lipodistrophy, and alopecia. In most cases of this disease, a single de novo mutation is responsible for causing the production of progerin, leading to a shortened life span. Unfortunately, sufferers rarely live past the age of thirteen.

The research team decided to run a literature meta-analysis on genes associated with each symptom of progeria. In all, seventeen genes implicated in all four symptoms were found, and of those seventeen, fourteen were part of the JAK-STAT pathway.

Baricitinib Inhibits Janus Kinases

Henceforth, to test the role of the JAK-STAT pathway in progeria experimentally, the team grew cells in culture from progeria patients and also from unaffected controls. The progeric cells expressed abnormal levels of the fourteen identified genes. When the researchers applied baricitinib to the cell culture, the gene expression levels normalized. After one month of baricitinib treatment, progeric cells were less likely to become senescent.

Furthermore, etoposide was also applied to the cell culture, which is known to worsen cell senescence. As anticipated, etoposide treatment disrupted expression of the fourteen genes.

In conclusion, this research shows that the JAK-STAT pathway is likely part of the Hutchinson-Gilford progeria disease mechanism, and baricitinib may have potential as a therapy.

 

Liu C, Arnold R, Henriques G, et al. Inhibition of JAK-STAT signaling with baricitinib reduces inflammation and improves cellular homeostasis in progeria cells. Cells. 2019 Oct 18;8(10):1276. doi: 10.3390/cells810276. PMID: 31635416.

Impact of 2-DG on Triple-Negative Breast Cancers

Triple-negative breast cancers present a difficult problem. Most existing therapies for breast cancer target hormone receptors on the cell surface to inhibit cell division. As such, breast cancers that lack these receptors, known as triple-negative cancers, are harder to treat. Physicians need more pharmaceutical options for treating these cancers.

A Possibility?

One promising molecule is 2-Deoxy-D-Glucose, which takes advantage of cancer cells’ altered metabolism. Some types of cancer cells depend on glycolysis as their source of energy, rather than oxidative phosphorylation, and so require more glucose than normal cells, which depend on oxidative phosphorylation for energy. Interestingly, 2-Deoxy-D-glucose is a toxic glucose analog that enters cells through normal glucose transporters. The toxicity should be more impactful to cancer cells than to normal cells because of the increased rate of uptake.

One Team’s Investigation

Recently, a team of researchers in Dublin tested 2-Deoxy-D-glucose’s effectiveness at treating breast cancer. They hypothesized that if 2-Deoxy-D-glucose worked as expected, then it should be more toxic to more aggressive, metabolically active cancers than less aggressive ones.

They tested two breast cancer cell lines, Hs578T, and its more aggressive variant, Hs578Ts(i)8. 2-Deoxy-D-glucose reduced the ability of the breast cancer cells to spread and migrate in vitro. The more aggressive cell line was more affected.

Normally when epithelial cells such as breast cancer travel through the blood or lymph system, they undergo apoptosis. Hence, cancer cells must have resistance to apoptosis in order to metastasize. The researchers tested the lines’ resistance to apoptosis. 2-Deoxy-D-glucose reduced the ability of the aggressive cell line to metastasize, but not the less aggressive one. Further evidence also suggests that the cancer stem cells present were directly affected by 2-Deoxy-D-Glucose treatment, in both cell lines.

Therefore, these results suggest that 2-Deoxy-D-glucose has the potential to treat triple-negative breast cancer, particularly the more aggressive variant in this study. Further studies may have a positive impact on developing treatments for the most aggressive and difficult to treat triple-negative breast cancers.

O’Neill S, Porter RK, McNamee N, et al. 2-Deoxy-D-Glucose inhibits aggressive triple-negative breast cancer cells by targeting glycolysis and the cancer stem cell phenotype. Sci Rep. 2019. 9:3788. doi: 10.1038/s41598-019-39789-9. PMID: 30846710.

 

 

Promising Mycobacteria Treatment: Bedaquiline

Bedaquiline, a potential treatment for several kinds of mycobacteria, was the first new drug to be approved for the treatment of tuberculosis in forty years back in 2012. This drug is especially important for the treatment of multidrug-resistant tuberculosis when first line treatments fail. It works by preventing the mycobacterium from making ATP, which is a different mechanism from older treatments.

Bedaquiline has attracted interest from public health researchers for the treatment of non-tuberculous mycobacteria. These bacteria infect lungs and wounds, especially in immunocompromised patients. In rich countries, non-tuberculous mycobacterial infections cause a greater health burden than tuberculosis itself does. These infections are difficult to treat because, as with tuberculosis, no effective drugs have been developed recently.

Researchers at the University of Texas Health Science Center have begun investigating the potential for developing a new treatment for this type of infection using bedaquiline. To begin, they first collected isolates of non-tuberculous mycobacteria from lungs and wounds of infected patients and grew them in nutrient broth. The isolates were then tested using broth microdilution antimicrobial susceptibility testing (AST). They calculated the minimum amount of bedaquiline they needed to add to the broth to inhibit bacterial growth, the minimum inhibitory concentration. They found that the required concentrations should be achievable in patients’ blood, so bedaquiline has potential to treat non-tuberculous mycobacterial infections.

In considering bedaquiline for the treatment of mycobacteria, researchers caution that bedaquiline should not be used as a monotherapy, because of the potential for bacteria to develop resistance.

 

Bedaquiline Fumarate

 

Brown-Elliot BA, Wallace RJ. 2018. In vitro susceptibility testing of bedaquiline against mycobacterium absceccus complex. Antimicrobial Agents and Chemotherapy. 29:63(2). doi: 10.1128/AAC.01919-18. PMID: 30509936

 

Now that you’ve read about it, find out how to pronounce it too!

 

Okadaic Acid for Alzheimer’s Research

New discoveries are one step closer with a new application using okadaic acid in Alzheimer’s research. Alzheimer’s disease is difficult to model in non-human animals. Recently, a collaboration between Indian and American researchers proposed a treatment combination that could produce rats with more biomarkers of Alzheimer’s disease than previous models.

Hypoxia increases the amount of misfolded amyloid beta aggregates in the brain, a well-known biomarker of Alzheimer’s disease. However, hypoxia does not cause tau tangles, which is another biomarker of Alzheimer’s disease. Okadaic acid is a toxin that is known for causing diarrhetic shellfish poisoning. It selectively inhibits phosphatases, so it is often used as a research chemical to study phosphorylation. As it turns out, in the brain it hyperphosphorylates tau, which causes it to tangle.

A combination of hypoxia and okadaic acid treatment therefore should produce rats with more biomarkers of Alzheimer’s disease than either treatment alone.

This collaborative research team microinjected okadaic acid into live rat brains, then placed the rats in a hypoxic chamber with 10% oxygen (atmosphere contains about 21%) for three days. The treated rats fared worse at an electrical shock avoidance test and a water maze memory test.

The team then sacrificed the rats and analyzed their brain biochemistry. As predicted, hypoxia increased the amount of amyloid beta aggregates in the rat brains, and okadaic acid increased the number of hyperphosphorylated tau tangles. Rats that received the combination treatment also had decreased acetylcholine esterase activity and increased oxidative damage, which are also biochemical hallmarks of Alzheimer’s disease.

This combination treatment of hypoxia plus okadaic acid in rats should be useful for further advancing the research into Alzheimer’s disease.

 

Okadaic Acid

Okadaic Acid Ammonium

Okadaic Acid Sodium

 

Kaushal A, Wani WY, Bal A, Gill KD, Kaur J. Okadaic acid and hypoxia induced dementia model of Alzheimer’s type in rats. 2019. Neurotoxicity Research.  PMID: 30729451

 

 

The Metabolic Impact of Kynurenic Acid

Background

Kynurenic acid is a metabolite of tryptophan. This chemical is found throughout the body, and appears to act on glutamate receptors in the brain. One effect of Kynurenic acid on Gpr35 signaling that has been discovered is enhanced cellular respiration.

Interestingly, high levels of kynurenic acid have been found in the brains of patients with schizophrenia. Further research is ongoing to understand its role in that disease. Less is known about its role in the rest of the body.

Kynurenic Acid Combined with Consistent Exercise and Feeding

One relationship that has been discovered is that exercise causes the levels of kynurenic acid to increase in skeletal muscle. Recently, Agudelo et al. sought to tease the effects of kynurenic acid on metabolism apart from the effects of exercise alone.

To accomplish this, mice were dosed with kynurenic acid without changing their exercise habits. Their metabolisms then sped up, but their level of exercise and feeding stayed the same. As a result, the mice lost some weight after two weeks, which came from a reduction in their white fat stores.

Kynurenic Acid Combined with Altered Diets and Genetics

Previous research has shown that kynurenic acid activates the receptor protein Gpr35. Agudelo et al. wanted to test whether Gpr35 was involved in the relationship between kynurenic acid and metabolism.

To test the effect of Kynurenic acid on Gpr35 signaling, they put mice on a high-fat diet that causes them to gain weight. When they dosed the mice on the high-fat diet with kynurenic acid, they prevented the mice from gaining weight.

When they dosed mice that lack Gpr35 with kynurenic acid, the mice gained weight as usual. These results suggest that Gpr35 signaling is important for kynurenic acid’s role in raising metabolism.

 

In conclusion, this study increases the understanding of both kynurenic acid and Gpr35. A therapeutic application for kynurenic acid is a long way off, but worth studying.

 

K977545  Kynurenic Acid

 

Agudelo LZ, Ferreia DMS, Cervenka I, et al. Kynurenic acid and Gpr35 regulate adipose tissue energy homeostasis and inflammation. 2018. Cell Metabolism. 27(2):378-392. PMID: 29414686.

Chemicals for Pharmaceutical Research for the Novel Coronavirus, COVID-19

The coronavirus known as COVID-19 first appeared in December, 2019 and spread around the world within a matter of days. As of this writing, it has infected nearly 400,000 people in 169 countries.

Scientists around the world have stopped their normal research to focus on creating a vaccine and treatment for this illness which has killed more than 17,000 people worldwide. Fortunately, more than 100,000 have recovered.

On March 22, 2020, an international team of scientists published a research paper preprint on biorXiv analyzing the interaction between the novel coronavirus and human proteins.* Their analysis predicts 332 protein-protein interactions and 69 existing pharmaceuticals that might perturb these interactions. The researchers propose that these drugs may be candidates for treating COVID-19 infections.

 LKT Laboratories has a number of these proposed chemicals for COVID-19 research in stock that can be shipped within 24 hours:

We also have various other antiviral compounds available:

See complete list of available antiviral compounds here

*A SARS-CoV-2-Human Protein-Protein Interaction Map Reveals Drug Targets and Potential Drug-Repurposing, David E. Gordon et al., bioRxiv 2020.03.22.002386; doi: https://doi.org/10.1101/2020.03.22.002386.

LKT Laboratories is a biochemical supply company focused on the synthesis, purification, and isolation of small molecules for research applications. All laboratory activities, including synthesis, natural product isolation, and full analytical characterization of our products are performed at our headquarters in St. Paul, MN.  Call or email us if you have questions about the chemicals above or have a need for other chemicals not listed.

Recombinant AMPs May Be More Effective Antibacterials

Background:

Antimicrobial peptides (AMPs) are short strings of amino acids, about 12-50 residues long, that show potent antibacterial, antiviral, and antifungal activity. They are found throughout the tree of life as part of the innate immune system. Many AMPs are in clinical use, such as vancomycin.

A class of AMPs called the cecropins were first isolated from the moth Hyalophora cecropia. Magainins were first isolated from the frog Xenopus laevis. An analog of magainin went through clinical trials as a treatment for infected diabetic foot ulcers, but failed.

Research Inspiration:

Researchers from the Jilin Agricultural University in China are interested in developing AMPs for livestock feed as an alternative to antibiotics. Previous research suggested that the fusion of peptides from two AMPs may enhance their antibacterial activity. Zhang et al. decided to test the properties of a magainin II – cecropin B fusion.

The group was also interested in testing whether the fungus Cordyceps militaris would make a suitable expression vehicle for fusion proteins. They constructed a plasmid that coded for the magainin II – cecropin B fusion and transformed cordyceps to express it. Then they extracted protein from the transformed fungus.

New Testing:

They tested the extract using ELISA, PAGE, and Western blotting and found that the cordyceps did express the fusion protein. Then, they swabbed the protein onto plates containing various species of bacteria to test whether it inhibited bacterial growth. Magainin II – cecropin B inhibited bacterial growth better than cecropin B alone.

The researchers also administered magainin II – cecropin B to mice infected with E. coli. The fusion inhibited E. coli growth in the mouse gut, and the mice suffered less intestinal damage. The same effect was observed when they fed the transformed cordyceps straight to the mice.

Zhang et al. conclude that magainin II – cecropin B is an effective antimicrobial. Cordyceps militaris that expresses magainin II – cecropin B could potentially be added to livestock feed.

 

C1609 Cecropin B
M0124 Magainin 1
M0126 Magainin 2

 

Zhang M, Shan Y, Gau H, Wang B, Liu X, Dong Y, Liu X, Yao N, Zhou Y, Li X, Li H. Expression of a recombinant hybrid antimicrobial peptide magainin II-cecropin B in the mycelium of the medicinal fungus Cordyceps militaris and its validation in mice. 2018. Microb Cell Fact. 17:18. PMID: 29402269.

Uncovering Markers for Parkinson’s Disease with 6-Hydroxydopamine

6-Hydroxydopamine is a dopamine analogue that selectively destroys dopaminergic neurons. It is used in biomedical research to destroy the substantia nigra in lab animals and induce Parkinson’s-like symptoms.

Choi et al. were interested in studying the early stages of Parkinson’s disease. Before the onset of motor symptoms, patients suffer from poor gastric emptying and constipation. Previous research suggests that Parkinson’s disease is also associated with changes in gut microbiome. Choi et al. sought to test whether Parkinson’s-like brain lesions directly caused changes in gut microbiome.

To test this, they injected 6-hydroxydopamine into mice. Two weeks later, they collected fecal samples from the mice, then extracted and sequenced 16S rRNA to identify microbial species.

Injected mice and control mice had about the same microbial species richness in their feces, but species composition changed. Injected mice contained fewer bacteria from the genus Lactobacillus and more from the genus Bacteroides. The researchers suggest that the Parkinson’s-lesioned brain might affect gut microbia through changes in the firing of the vagus nerve.

H966144 6-Hydroxydopamine Hydrobromide

 

Choi JG, Huh E, Kim N, Kim D-H, Oh MS (2019). High-throughput 16S rRNA gene sequencing reveals that 6-hydroxydopamine affects gut microbial environment. PLoS ONE 14(8): e0217194. https://doi.org/10.1371/journal.pone.0217194

HDAC Inhibitor LMK-235 Promotes Odontoblast Differentiation

Dental pulp, the living tissue in the core of teeth, contains stem cells. Dental pulp stem cells are of medical interest because they can differentiate into odontoblasts, osteoblasts, adipocytes, and chondrocytes, and because they can be obtained using minimally invasive methods.

The mechanism of dental pulp stem cell differentiation is not currently understood. Liu et al. suspect that epigenetic modifications controlled by histone deacetylaces (HDACs) play a role. Previous studies have shown that HDAC inhibition promotes stem cell differentiation into odontoblasts.

The molecule LMK-235 is an inhibitor of HDAC4 and HDAC5. Recently, Liu et al. investigated whether LMK-235 can promote dental pulp cell differentiation into odontoblasts. They cultured dental pulp cells from waste wisdom teeth and applied a series of doses of LMK to the culture fluid.

At high doses, LMK-235 inhibits cell proliferation. Liu et al. used a low dose, 100nM, for the rest of the experiment. At 100nM, LMK-235 increased the mRNA expression of genes associated with differentiation such as DSPP, ALP, and Runx2. A Western blot showed that LMK-235 increased the protein expression of DSPP and Runx2. The treated cells also showed more calcified nodules in culture.

Liu et al. acknowledge that their evidence in this study is indirect, because the cultured cells did not fully differentiate into odontoblasts. However, the results show that dental pulp cells hold promise for the field of regenerative medicine.

L493400 LMK-235

 

 

Liu Z, Chen T, Han Q, Chen M, You J, Fang F, Peng L, Wu B. HDAC inhibitor LMK-235 promotes the odontoblast differentiation of dental pulp cells. 2018. Molecular medicine reports. 17:1445-1452.

Dietary Phytochemicals Exhibit Multiple Mechanisms of Action Against Pathogenic Bacteria

Isothiocyanates are a family of biologically active phytochemicals found naturally in cruciferous plants. They have been investigated for their antioxidative, anti-inflammatory, and anticancer effects. They have also shown activity against neurodegenerative diseases. Recently, their properties as antibacterial agents were investigated by Nowicki, et al.

Mechanisms for two isothiocyanates, sulforaphane and phenethyl isothiocyanate, were studied in multiple strains of bacteria.  These strains included clinical isolates of E. coli, K. pneumoniae, S. aureus, S. epidermidis, and E. faecalis. In strains where growth inhibition by isothiocyanates is independent of (p)ppGpp production, the inhibition of nucleic acid synthesis and cell viability may be due to a drop in GTP levels. In strains which do not produce (p)ppGpp upon treatment such as B. subtilis, the isothiocyanates compromise the integrity of the cytoplasmic membrane. They concluded that isothiocyanates likely have more than one target in bacterial cells, and that the mechanisms of action may be species-specific. Although the mechanisms change the resulting inhibition of bacterial growth is the same across multiple strains.

LKT Labs offers a wide variety of isothiocyanate molecules for research use.

 

S8044 R,S-Sulforaphane

E6880 Erucin

I0416 Iberin

I74571-Isothiocyanato-6-(methylsulfinyl)-hexane

Full List of ITCs

 

References:

Nowicki D., Maciag-Dorszynska M. et al. Various modes of action of dietary phytochemicals, sulforaphane and phenethyl isothiocyanate, on pathogenic bacteria. Sci Rep. 9(1):13677 (2019). doi: 10.1038/s41598-019-50216-x.