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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.

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

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.

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.

Most cancer cells get their energy through glycolysis instead of oxidative phosphorylation, even in the presence of oxygen. This process is named the Warburg effect after its discoverer, and it allows cells to proliferate even with damaged mitochondria. In 2008, researchers at Harvard Medical School discovered that one form of pyruvate kinase, PKM2, is required for the Warburg effect. The other form of pyruvate kinase is not involved. These findings make PKM2 an interesting target for developing cancer therapies.

The P13K/Akt/mTOR regulatory pathway is upstream of PKM2. The small molecule LY294002 targets P13K, so recently Lu et al. tested its effect on cancer cell proliferation.

Lu et al. grew several lines of gastric cancer cells in culture. A Western blot analysis found that PKM2 expression was increased in cancer cell lines compared to the control. They chose one cell line to study in detail. LY294002 decreased cell proliferation and increased apoptosis in this line. LY294002 also decreased the activity of lactate dehydrogenase, a biomarker of the Warburg effect.

They wanted to test whether PKM2 was part of the mechanism by which LY294002 decreased cell proliferation, so they used siRNA to knock down PKM2 on its own. siRNA-treated cells behaved similarly to LY294002-treated cells: they had lowered proliferation, increased apoptosis, and lowered lactate dehydrogenase activity. Lu et al. concluded that PKM2 is important to the mechanism of LY294002’s action.

LY294002 shows promise as an inhibitor of PKM2 and the Warburg effect.

L4796 LY-294002

L960002 LY-294002 Hydrochloride

Lu J, Chen M, Gao S, Yuan J, Zhu Z, Zou X. LY294002 inhibits the Warburg effect in gastric cancer cells by downregulating pyruvate kinase M2. 2018. Oncology letters. 15:4358-4364.

The xanthones are a diverse class of natural products that can be extracted from plants, fungi, lichen, and invertebrates. They have a wide range of biological activities, including antitumor and antimicrobial activity.

DMXAA, a synthetic derivative of xanthone, attracted particular interest in the 2000s because it disrupts tumor blood supply in mice. In 2008 it entered Phase III clinical trials for non-small cell lung cancer. It failed to show benefit in humans.

Recently, Shih et al. investigated the failure of DMXAA to translate across species. In mice, DMXAA activates the STING (stimulator-of-interferon-genes) protein, which leads to an immune response against tumors. DMXAA does not activate human STING.

The binding pockets of human and mouse STING are identical. So what causes the difference in DMXAA effectiveness? Shih et al. used molecular dynamics, a computational method that simulates the movements of molecules. When they simulated the binding of DMXAA to human STING and mouse STING, they found that the lid of mouse STING remains closed, preventing bound DMXAA from leaving. In human STING, the DMXAA leaves. A peptide residue in the STING lid region is responsible for the difference.

This work may aid in the rational design of a STING activator, but the researchers conclude that the design of such a drug would be challenging.

D509921 DMXAA

STING Activators

Shih AY, Damm-Ganamet KL, Mirzadegan T. Dynamic Structural Differences between Human and Mouse STING Lead to Differing Sensitivity to DMXAA. 2018. Biophysical Journal. DOI: 114:32-39.

MELK (maternal embryonic leucine zipper kinase) signals cell division and may play a role in several kinds of cancer. In 2012, researchers screened for inhibitors of MELK and found a substance that they named OTSSP167. OTSSP167 shows promise as a chemotherapy drug.

Bone disease is a top cause of morbidity for multiple myeloma patients. Bone lesions cause bone pain, bone breakdown, and encourage further tumor growth. Even when chemotheraphy causes tumor remission, the bone lesions don’t heal. Bisphosphonates, the current standard of care, come with serious side effects.

Researchers Muller and Bolomsky investigated OTSSP167’s potential to treat multiple myeloma. In 2018, Bolomsky et al. found that OTSSP167 reduced tumor load in a multiple myeloma mouse model. As predicted, it worked by inhibiting MELK. The researchers also found that OTSSP167 reduced multiple myeloma bone disease, even at doses that were too low to inhibit tumor growth. They followed up on their findings in another 2018 paper.

In the follow-up, Muller et al. dosed bone cell cultures and multiple myeloma mice with OTSSP167. They found that OTSSP167 inhibits the growth and function of osteoclasts, cells that reabsorb bone, and stimulates osteoblasts, cells that produce bone. The mice dosed with OTSSP167 had fewer bone lesions and better bone volume than controls.

Muller et al. conclude that OTSSP167 has the potential to treat multiple myeloma tumors and to reduce bone lesions.

O783743 OTSSP167 Hydrochloride

Chung S, Suzuki H, Miyamoto T, et al. Development of an orally-administrative MELK-targeting inhibitor that suppresses the growth of various types of human cancer. Oncotarget. 2012 3(12):1629–1640. doi:10.18632/oncotarget.790

Muller J, Bolomsky A, Dubois S, Duray E, Stangelberger K, Plougonven E, Lejeune M, Léonard A, Marty C, Hempel U, Baron F, Beguin Y, Cohen-Solal M, Ludwig H, Heusschen R, Caers J. Maternal embryonic leucine zipper kinase inhibitor OTSSP167 has preclinical activity in multiple myeloma bone disease. Haematologica. 2018 Vol 103(8):1359-1368.

Bolomsky A, Heusschen R, Schlangen K, et al. Maternal embryonic leucine zipper kinase is a novel target for proliferation- associated high-risk myeloma. Haematologica. 2018 103(2):325-335.

Rose bengal and fluorescein can stain damaged conjunctival and corneal tissue in the eye. They play an important role in ophthalmology to diagnose dry eye and eye surface damage. The mechanism these stains use to stain damaged cells and not healthy ones is not understood.

Dynasore is a small molecule that inhibits dynamin. Dynamin is essential for endocytosis in eukaryotic cells, so dynasore inhibits endocytosis. Dynasore is used as a cell biology research tool.

Recently, Webster et al. proposed a mechanism for how rose bengal and fluorescein work. Sublethal cell damage causes the cell to repair itself by remodeling its plasma membrane. While remodeling the plasma membrane, the cell might take up stain via endocytosis. They tested their hypothesis by applying oxidative stress to monolayer cultures of human corneal epithelial cells. The oxidative stress caused an increase in both stain uptake and endocytosis. Then they applied the endocytosis inhibitors chlorpromazine hydrochloride, genistein, Dynasore hydrate, and Dyngo-4a (a Dynasore derivative). Stain uptake was blocked.

However, when they repeated the experiment in whole eye tissue harvested from mice, oxidative stress increased stain uptake, but did not increase endocytosis. Most of the endocytosis inhibitors did not block stain uptake. Dynasore and Dyngo-4a did.

If eye cell damage increased stain uptake but not endocytosis, endocytosis must not be the mechanism for cell uptake. Then why did two of the endocytosis inhibitors, Dynasore and its derivative, inhibit stain uptake if endocytosis was not involved?

Webster et al. performed cytotoxicity and Western blotting assays and concluded that Dynasore and Dyngo-4a prevented oxidative damage to the cells. The results have implications for the field of ophthalmology. Dynasore and Dyngo-4a may have therapeutic potential.

In 2008, Yu et al. identified a compound that dorsalizes structures in growing zebrafish embryos, which they named dorsomorphin. This compound inhibits the bone morphogenetic protein (BMP) signaling pathway, which plays an important role in development and cell differentiation.

Recently, Valizadeh-Arshad et al. hypothesized that small molecules like dorsomorphin could be used to promote human embryonic stem cells to differentiate into motor neurons. One of the goals of regenerative medicine is to produce tissues such as neurons from stem cells, to heal nerve damage that will not heal on its own. Currently, coaxing embryonic stem cells to differentiate into motor neurons is expensive and inefficient.

The researchers modified an existing motor neuron differentiation protocol to include a cocktail of small molecules that have shown promise in previous studies: all-trans retinoic acid, dorsomorphin, A8301, and XAV939. They cultured the embryonic stem cells on plates, and exposed the cells to the small molecules as well as established differentiation factors.

They then used flow cytometry and immunofluorescence staining on the cells to test for expression of genes associated with neurons, such as NESTIN, PAX6, and MAP2. The cells expressed these marker genes with efficiencies greater than 50%. The cells showed voltage-gated currents in a patch-clamp experiment, suggesting the presence of both K+ and Ca++/Na+ channels. However, the cells were unable to generate more than single action potentials. More research needs to be done before this cell differentiation method can produce mature motor neurons.

D582703 Dorsomorphin

D582705 Dorsomorphin Dihydrochloride

R1877 all-trans-retinol, ≥98%

Valizadeh-Arshad Z, Shahbazi E, Hashemizadeh S, Moradmand A, Jangkhah M, Kiani S. In Vitro Differentiation of Neural-Like Cells from Human Embryonic Stem Cells by A Combination of Dorsomorphin, XAV939, and A8301. Cell J. 2018 19:4. doi: 10.1038/nbt1201-1129.

Yu PB, Hong CC, Sachidanandan C, et al. Dorsomorphin inhibits BMP signals required for embryogenesis and iron metabolism. Nat Chem Biol. 2007;4(1):33–41. doi:10.1038/nchembio.2007.54.

When food or feed crops are stored in hot, humid conditions, fungi that live on them can produce mycotoxins that threaten human and animal health. Even minute quantities of mycotoxins can cause disease. For example, aflatoxins are potent carcinogens, ochratoxin has been implicated in kidney disease, and zearalenone is an estrogen mimic that can cause infertility or miscarriage. Deoxynivalenol is a threat to livestock because when it is present in feed, the livestock fail to gain weight.

The European Commission sets strict maximum limits on mycotoxin concentrations in crops used for food or feed in Europe. However, the regulations never mention insects or insect feed. Edible insects are a promising emerging crop because they produce protein more efficiently and with less pollution than larger livestock animals. The European legal limit of mycotoxins in edible insects is not clear.

Recently, Camenzuli et al. set out to clarify the safety of mycotoxin exposure in edible insects. They studied two promising food insect species, the lesser mealworm (Alphitobius diaperinus) and the black soldier fly (Hermetia illucens). The researchers spiked larvae feed with aflatoxin B1, deoxynivalenol, ochratoxin A and zearalenone at 1, 10 and 25 times the limit allowed for livestock feed. They found no effect on the survival or weight gain for either species, except for lesser mealworms given the highest level of ochratoxin A, which gained less weight.

Camenzuli et al. also tested for accumulation of the mycotoxins in the larvae. They could not detect any of the mycotoxins in the lesser mealworms, even when given the highest doses. In the black soldier fly, they could not detect mycotoxins when larvae were given low doses, and found only minute quantities of deoxynivalenol, zearalenone, and ochratoxin at the highest doses.

The metabolites of mycotoxins might also pose a threat to human or livestock health. For example, the zearalenone metabolite α-zearalenol is a more potent estrogen mimic than zearalenone itself. To account for this, the researchers tested for the accumulation of aflatoxicol, aflatoxin P1, aflatoxin Q1, aflatoxin M1, 3-acetyl-DON, 15-acetyl-DON, DON-3-glycoside, and α- and β-zearalenol in the larvae. None of the mycotoxin metabolites were detectable in the lesser mealworms. In the black soldier fly larvae, aflatoxin and deoxynivalenol metabolites were undetectable. Low concentrations of α- and β-zearalenol were found in the black soldier fly larvae at all doses.

Camenzuli et al. concluded that food source insects might be able to tolerate higher concentrations of mycotoxins in their feed than other livestock, but more research is needed.

Z1602 Zearalenone

Z161024 α-zearalenol

Z161025 β-zearalenol

Full list of available mycotoxins

Camenzuli L, Van Dam R, Rijk T, Andriessen R, Van Schelt J, Van der Fels-Klerx HJ. Tolerance and Excretion of the Mycotoxins Aflatoxin B1, Zearalenone, Deoxynivalenol, and Ochratoxin A by Alphitobius diaperinus and Hermetia illucens from Contaminated Substrates. Toxins 2018, 10, 91; doi:10.3390/toxins10020091

Palmatine is an isoquinoline alkaloid naturally found in plant species such as Corydalis and Phellodendron. It exhibits a wide array of biological effects, such as sedative, antidepressant, antioxidative, anticancer, and antacid activities. In a recent study by Chakravarthy, et al. at the University of Texas Health Science Center in San Antonio, Palmatine has shown potential as an agent for the clinical management of pancreatic cancer.

Advanced pancreatic ductal adenocarcinoma (PDAC) has a notoriously high mortality rate. Current therapies, primarily centered around gemcitabine treatment in combination with other agents, have shown modest success but are limited to select groups of patients.

Pancreatic stellate cells (PSCs) are considered to be the driver of pancreatic fibrosis and are activated by a number of factors, including inflammation. Once activated, PSCs are responsible for the expression of alpha smooth muscle actin and collagen 1 type 1 alpha 1 (COL1A1). Pancreatic cancer cells (PCCs) also activate PSCs. Inhibiting the growth of activated PSCs and PCCs with novel compounds has become one possible strategy for combating PDAC.

Palmatine is one such compound. Chakravarthy, et al. show that palmatine inhibits both the growth of PSCs and inhibits the sonic hedgehog pathway. By disrupting the interaction between PSCs and PCCs, palmatine treatment may be a viable method of clinical management of PDAC, either alone or in conjunction with a chemotherapy agents like gemcitabine.

LKT Labs offers palmatine and other chemotherapy agents like gemcitabine for research use.

P0245 Palmatine

G1745 Gemcitabine Hydrochloride

I6932 Irinotecan

O9201 Oxaliplatin

References:

Chakravarthy D, Munoz A, Su A, et al. Palmatine suppresses gluatmine-mediated interaction between pancreatic cancer and stellate cells through simultaneous inhibition of survivin and COL1A1.  Cancer Lett. 2018 Apr 10;419:103-115. doi: 10.1016/j.canlet.2018.01.057

Bee venom is a complex mixture of enzymes, polypeptides, amino acids, and sugars. Traditional Chinese medicine uses bee venom acupuncture to treat arthritis and pain. However, the components of bee venom are the subject of biomedical research for their potential painkiller, antithrombotic, and antibiotic properties. The polypeptide melittin makes up 40-60 percent of the dry weight of bee venom and causes the pain of bee stings. Apamin, which makes up 2-3 percent of bee venom dry weight, is a neurotoxin that inhibits Ca++ -activated K+ channels in the central nervous system. It is used in biomedical research to study how these channels work.

In South Korea, manufacturers put bee venom extracts into skin care products, citing the benefits of traditional medicine. Consumers who use these products have inadvertently found an antifungal effect.

Recently, Park et al. investigated the antifungal properties of bee venom. The experimenters prepared cultures of Trichophyton rubrum, the pathogen responsible for athlete’s foot and jock itch, on potato dextrose cornmeal agar plates. They exposed each culture to one of four different treatments: raw bee venom, a commercial bee-venom-based skincare product, apamin, or melittin. They let each T. rubrum culture grow for two weeks.

Every two days, the experimenters calculated the growth rate of each T. rubrum culture. They found that melittin and apamin do not inhibit T. rubrumgrowth, but raw bee venom and the skincare product do inhibit growth. They conclude that bee venom does have antifungal potential, but neither melittin nor apamin can inhibit fungus alone. Bee venom will need more investigation before it can see clinical use.

A6002 Apamin

M1744 Melittin

Park J, Kwon O, An HJ, Park KK. Antifungal Effects of Bee Venom Components on Trichophyton rubrum: A Novel Approach of Bee Venom Study for Possible Emerging Antifungal Agent. (2018). Annals of Dermatology 30:2. doi: 10.5021/ad.2018.30.2.202.

Valproic acid is an anticonvulsant drug that was first synthesized in 1882 and thought to have no biological activity. In 1962, Pierre Eymard discovered its anticonvulsant properties by accident when he used it as a carrier for other anticonvulsant drugs in a trial on rats. Today, valproic acid is on the World Health Organization list of essential medicines and a common treatment for epilepsy.

Valproic acid also has FDA approval for the treatment of bipolar disorder. Its mechanism of action is not fully understood. It may work by increasing levels of GABA in the brain or by inhibiting histone deacetylase and thereby altering brain gene expression. In 2018, Joshi et al. hypothesized that valproic acid and the mood stabilizer lithium alter the expression levels of synapsin, proteins expressed in neurons that regulate synapse function, including vesicle maintenance and neurotransmitter release.

The researchers dosed rats with lithium, valproic acid, or saline twice daily for two weeks. RNA was then extracted from the brain tissue of the rats, and real-time PCR was used to measure the synapsin expression level. Rats dosed with lithium or valproic acid showed increases in synapsin expression across several brain tissues. Specifically, synapsin IIa increased by about 25% in the hippocampus and prefrontal cortex, and synapsin IIb increased by 25-50% in the hippocampus and striatum. Both lithium- and valproic-acid-dosed rats saw these increases.

Valproic acid may work to treat epilepsy and bipolar disorder through the upregulation of synapsins. LKT Laboratories carries valproic acid as well as a number of anticonvulsant and antiepileptic molecules for research use.

V0148 Valproic Acid

C0270 Carbamazepine

O9210 Oxcarbazepine

Z5653 Zonisamide

Joshi H, Sharma R, Prashar S, Ho J, Thomson S, Mishra R. Differential Expression of Synapsin I and II upon Treatment by Lithium and Valproic Acid in Various Brain Regions. International Journal of Neuropsychopharmacology (2018) 21(6): 616–622.

Palbociclib is a chemotherapy drug used to treat advanced breast cancers. In a phase 3 clinical trial, a combination of palbociclib and fulvestrant more than doubled median progression-free survival time in women with ER+, HER- breast cancer compared to fulvestrant alone. Palbociclib received accelerated approval from the FDA in 2015 for ER+ breast cancers, and in 2017 was approved for the treatment of HER2- breast cancers.

The cyclin-dependent kinases CDK4 and CDK6 cause cells to pass from the G1 phase to the S phase and divide. Palbociclib works by selectively inhibiting these kinases.

Recently, Miettinen et al. argued that palbociclib’s remarkable effectiveness against breast cancer can not be explained by CDK4 and CDK6 inhibition alone. They used a method called cellular thermal shift assay to investigate other targets of palbociclib within the cell. This assay measures changes in the thermal stability of proteins in living cells, which can be used to determine which proteins are bound or modified by the drug of interest.

Miettinen et al. found that palbociclib targets the proteasome in a breast cancer cell line. Palbociclib activates the proteasome by preventing the suppressor protein ECM29 from binding to it. The authors speculate that tightly regulated proteasome activity is required for cell division, so palbociclib’s activation of the proteasome could be another way that it treats breast cancer.

Miettinen TP, Peltier J, Hartlova A, Gierlinski M, Jansen VM, Trost M, Bjorklund M. Thermal proteome profiling of breast cancer cells reveals proteasomal activation by CDK4/6 inhibitor palbociclib. (2018). doi: 10.15252/embj.201798359.

Tedizolid is a member of the oxazolidinone class of antibiotics. These antibiotics are considered drugs of last resort against multiple drug resistant infections such as methicillin-resistant Staphylococcus aureus (MRSA). As part of a program to encourage new antibiotics to combat drug resistance, the FDA fast-tracked the approval of tedizolid for MRSA skin and skin structure infections in 2014.

Tedizolid works by binding to the 50S ribosomal subunit in bacteria, which inhibits protein synthesis.

The medical community often repurposes FDA-approved drugs to treat new diseases. Recently, Tang et al. investigated tedizolid’s potential to treat M. abscessus complex, a mixture of M. abscessus, M. massiliense, and M. bolletii bacteria. M. abscessus complex is notoriously difficult to treat when it infects the lungs. The standard therapy of clarithromycin and amikacin has only a 30-50% cure rate.

Tang et al. compared tedizolid’s effectiveness to clarithromycin and linezolid, another oxazolindone antibiotic. They applied a series of concentrations of antibiotic to M. abscessus cultures to determine the minimum inhibitory concentration (MIC). Tedizolid has a comparable MIC to linezolid and a lower MIC than clarithromycin.

A time-kill assay determined that tedizolid is bacteriostatic, not bactericidal against M. abscessus complex. Pre-exposure to low concentrations of tedizolid did not induce resistance. Tedizolid does not have antagonistic interactions with other antibiotics. Together, these experiments suggest tedizolid could be used in combination therapy to treat M. abscessus complex.

LKT Labs carries a number of antiobiotic compounds for research use, including:

A5132 Amikacin Disulfate

C4502 Clarithromycin

L3453 Linezolid

T165131 Tedizolid

Tang YW, Cheng B, Yeoh SF, Lin RTP, Teo JWP. Tedizolid Activity Against Clinical Mycobacterium abscessus Complex Isolates-An in vitro Characterization Study. Front Microbiol. 2018 Sep 7;9:2095. doi: 10.3389/fmicb.2018.02095.