Further exploration of the structure-activity relationship of dual soluble epoxide hydrolase/fatty acid amide hydrolase inhibitors

Synthesis and evaluation of isoquinolinyl and pyridinyl-based dual inhibitors of fatty acid amide hydrolase and soluble epoxide hydrolase to alleviate orofacial hyperalgesia in the rat

The treatment of orofacial pain disorders is poor. Both opioids and serotonin agonists are commonly used; however, they produce dangerous and unpleasant side effects. Therefore, there is an urgent need to identify new pharmacological treatments that can resolve orofacial pain. Moreover, a treatment that engages multiple mechanisms using one compound may be advantageous. Fatty acid amide hydrolase (FAAH) and soluble epoxide hydrolase (sEH) are two enzymes that can regulate both pain and inflammation via independent pathways. Small molecules that inhibit both enzymes simultaneously were previously synthesized and produced antinociception in vivo. Quinolinyl-based dual inhibitors of FAAH and sEH can inhibit acute inflammatory pain in rats. Here, following on these findings, we generated 7 new isoquinolinyl- and 7 pyridinyl-based analogs and tested their inhibition at both enzymes. Structure-activity relationship study coupled with docking experiments, revealed that the isoquinoline moiety is well-tolerated in the binding pockets of both enzymes, yielding several analogs with nanomolar activity in enzymatic assays. All newly synthesized analogs were assessed in the solubility assay at pH 7.4, and we determined that isoquinolinyl- and substituted pyridinyl-analogs exhibit limited solubility under the experimental conditions. The most potent inhibitor, 4f, with IC50 values in the low nanomolar range for both enzymes, was evaluated in a plasma stability assay in human and rat plasma where it showed a moderate stability. Primary binding assays revealed that 4f does not engage any opioid or serotonin receptors. A high dose (3 mg/kg) of 4f reversed orofacial hyperalgesia following pretreatment with nitroglycerin and orofacial injection of formalin; however, this same dose did not inhibit acute orofacial inflammatory pain or restore pain-depressed wheel running. These findings indicate that simultaneous inhibition of FAAH and sEH using isoquinolinyl-based dual inhibitors may only reverse certain components of orofacial hyperalgesia.

Structure-activity relationship studies and pharmacological evaluation of 4-phenylthiazoles as dual soluble epoxide hydrolase/fatty acid amide hydrolase inhibitors

Forty-two 4-phenylthiazole analogs, organized in two libraries 4a-u and 6a-u, were prepared and biologically evaluated in human fatty acid amide hydrolase (FAAH), and human, rat and mouse soluble epoxide hydrolase (sEH) inhibition assays. This structure-activity relationship (SAR) study explores the impact of electronic and steric changes on the molecule's potency and binding affinity to better understand the structural features important for dual sEH/FAAH inhibition which will guide the development of novel treatments for pain and inflammation. Our SAR revealed that electron-donating groups on the aromatic ring of the 4-phenylthiazole moiety are particularly well tolerated by both enzymes when placed at the ortho, meta and para positions; however, the overall 3D shape of the molecule is very important for the potent FAAH inhibition, suggesting more restricted size of the FAAH binding pocket compared to sEH binding pocket. Two selected dual inhibitors, 4p and 4s, were tested in the rat liver microsomes stability assays and evaluated in vivo in the formalin test. Systemic administration of 4p and 4s via intraperitoneal injection decreased nociceptive behavior (i.e., licking of the injected paw) in male rats, and this effect was dose-dependent for both compounds. Two doses, 1 and 3 mg/kg of 4p, decreased nociceptive behavior to a similar extent to that of 30 mg/kg ketoprofen, a traditional nonsteroidal anti-inflammatory drug. However, only 3 mg/kg of 4s decreased nociceptive behavior compared to vehicle-treated animals, and this effect was comparable to ketoprofen-treated animals. Taken together, these findings reveal the antinociceptive potential of 4-phenylthiazole-based dual FAAH and sEH inhibitors and suggest pharmacodynamic differences within this class of inhibitors despite similar potencies in vitro.

Lipidomics-driven drug discovery and delivery strategies in glioblastoma

With few viable treatment options, glioblastoma (GBM) is still one of the most aggressive and deadly types of brain cancer. Recent developments in lipidomics have demonstrated the potential of lipid metabolism as a therapeutic target in GBM. The thorough examination of lipids in biological systems, or lipidomics, is essential to comprehending the changed lipid profiles found in GBM, which are linked to the tumor's ability to grow, survive, and resist treatment. The use of lipidomics in drug delivery and discovery is examined in this study, focusing on how it may be used to find new biomarkers, create multi-target directed ligands, and improve drug delivery systems. We also cover the use of FDA-approved medications, clinical trials that use lipid-targeted medicines, and the integration of lipidomics with other omics technologies. This study emphasizes lipidomics as a possible tool in developing more effective treatment methods for GBM by exploring various lipid-centric techniques.

4-Phenyl-thiazole-based dual inhibitors of fatty acid amide hydrolase and soluble epoxide hydrolase do not alleviate orofacial inflammatory pain in female rats

Pain arising from trigeminal systems such as headache is common, debilitating, and current treatments (e.g., sumatriptan) are limited. New treatments that target novel mechanisms of action may be required to innovate both short- and long-term pain therapy. Fatty acid amide hydrolase and soluble epoxide hydrolase are two pain-related enzymes that regulate pain and inflammation via independent pathways. We have previously demonstrated that simultaneous inhibition of these enzymes using a novel dual inhibitor alleviates acute inflammatory pain in the hindpaw and does not depress wheel running in rats. Here, we expanded on these findings and performed structure-activity relationships of our lead compound, the 4-phenyl-thiazole-based dual inhibitor SW-17, to generate 18 analogs and tested them for their inhibition at both enzymes. Conversion of the sulfonamide group to a tertiary amine led to a general decrease in the potency for the sEH enzyme, while this change was well-tolerated at the FAAH enzyme yielding several strong inhibitors. Six selected inhibitors were evaluated in mouse and rat sEH inhibition assays and results showed a species difference, i.e. 4-phenyl-thiazole-based analogs are significantly less or not active in mouse sEH compared to human and rat enzymes. The most potent inhibitor, SW-17, was evaluated in a plasma stability assay in human and rat plasma and showed moderate stability. However, SW-17 did not alleviate orofacial inflammatory pain in female rats compared to the traditional anti-migraine agent sumatriptan. Although modification of 4-phenyl-thiazole-based dual inhibitor SW-17 changes potencies at both FAAH and sEH, these approaches may not produce antinociception against trigeminal pain. Key Words: polypharmacology, formalin, inflammation, enzyme inhibition, structure-activity relationship studies.

Quinolinyl-based multitarget-directed ligands with soluble epoxide hydrolase and fatty acid amide hydrolase inhibitory activities: Synthetic studies and pharmacological evaluations

Simultaneous inhibition of soluble epoxide hydrolase (sEH) and fatty acid amide hydrolase (FAAH) with a single small molecule represents a novel therapeutic approach in treating inflammatory pain, since both targets are involved in pain and inflammation processes. In this study using multi-target directed ligands methodology we designed and synthesized 7 quinolinyl-based dual sEH/FAAH inhibitors, using an optimized microwave-assisted Suzuki-Miyaura coupling reaction and tested their potency in human FAAH and human, rat, and mouse sEH inhibition assays. The structure-activity relationship study showed that quinolinyl moiety is well tolerated in the active sites of both enzymes, yielding several very potent dual sEH/FAAH inhibitors with the IC50 values in the low nanomolar range. The most potent dual inhibitor 4d was further evaluated in stability assay in human and rat plasma where it performed better than the standard Warfarin while in vivo study revealed that 1 mg/kg 4d can inhibit acute inflammatory pain in male rats to a similar degree as the traditional nonsteroidal anti-inflammatory drug ketoprofen (30 mg/kg) after intraperitoneal injection. ADMET prediction studies for this dual inhibitor show favorable pharmacokinetic properties which will guide the future in vivo evaluations.

Ceramides and ceramide synthases in cancer: Focus on apoptosis and autophagy

Different studies corroborate a role for ceramide synthases and their downstream products, ceramides, in modulation of apoptosis and autophagy in the context of cancer. These mechanisms of regulation, however, appear to be context dependent in terms of ceramides' fatty acid chain length, subcellular localization, and the presence or absence of their downstream targets. Our current understanding of the role of ceramide synthases and ceramides in regulation of apoptosis and autophagy could be harnessed to pioneer the development of new treatments to activate or inhibit a single type of ceramide synthase, thereby regulating the apoptosis induction or cross talk of apoptosis and autophagy in cancer cells. Moreover, the apoptotic function of ceramide suggests that ceramide analogues can pave the way for the development of novel cancer treatments. Therefore, in the current review paper we discuss the impact of ceramide synthases and ceramides in regulation of apoptosis and autophagy in context of different types of cancers. We also briefly introduce the latest information on ceramide synthase inhibitors, their application in diseases including cancer therapy, and discuss approaches for drug discovery in the field of ceramide synthase inhibitors. We finally discussed strategies for developing strategies to use lipids and ceramides analysis in biological fluids for developing early biomarkers for cancer.

Cytochrome P450 and Other Drug-Metabolizing Enzymes As Therapeutic Targets

Cytochrome P450 and other families of drug-metabolizing enzymes are commonly thought of and studied for their ability to metabolize xenobiotics and other foreign entities as they are eliminated from the body. Equally as important, however, is the homeostatic role that many of these enzymes play in maintaining the proper levels of endogenous signaling molecules such as lipids, steroids, and eicosanoids as well as their ability to modulate protein-protein interactions involved in downstream signaling cascades. Throughout the years, many of these endogenous ligands or protein partners of drug-metabolizing enzymes have been associated with a wide range of disease states from cancer to various cardiovascular, neurologic, or inflammatory diseases, prompting an interest in whether modulation of drug-metabolizing enzyme activity could have a subsequent pharmacological impact or lessening of disease severity. Beyond direct regulation of endogenous pathways, drug-metabolizing enzymes have also been proactively targeted for their ability to activate prodrugs with subsequent pharmacological activity or enhance the efficacy of a coadministered drug by inhibiting the metabolism of that drug through a rationally designed drug-drug interaction (i.e., ritonavir and human immunodeficiency virus antiretroviral therapy). The focus of this minireview will be to highlight research aimed at characterizing cytochrome P450 and other drug-metabolizing enzymes as therapeutic targets. Examples of successfully marketed drugs as well as early research efforts will be discussed. Finally, emerging areas of research utilizing typical drug-metabolizing enzymes to impact clinical outcomes will be discussed. SIGNIFICANCE STATEMENT: Although generally thought of for their drug-metabolizing capabilities, enzymes such as the cytochromes P450, glutathione S-transferases, soluble epoxide hydrolases, and others play a significant role in regulating key endogenous pathways, making them potential drug targets. This minireview will cover various efforts over the years to modulate drug-metabolizing enzyme activity toward pharmacological outcomes.

Structure-activity relationship studies of benzothiazole-phenyl analogs as multi-target ligands to alleviate pain without affecting normal behavior

Soluble epoxide hydrolase (sEH) and fatty acid amide hydrolase (FAAH) are potential targets for several diseases. Previous studies have reported that concomitant selective inhibition of sEH and FAAH produced antinociception effects in an animal model of pain. However, the co-administration of a selective sEH inhibitor and a selective FAAH inhibitor might produce serious side effects due to drug-drug interactions that could complicate drug development in the long term. Thus, discovering dual sEH/FAAH inhibitors, single small molecules that can simultaneously inhibit both sEH and FAAH, would be a significant accomplishment in the medicinal chemistry field. Herein, we report the synthesis and biological evaluation of benzothiazole-phenyl-based analogs as potential dual sEH/FAAH inhibitors. This work represents a follow-up structure-activity relationship (SAR) and metabolic-stability studies of our best dual sEH/FAAH inhibitor identified previously, as well as in vivo evaluation of its effects on voluntary locomotor behavior in rats. Our SAR study indicates that trifluoromethyl groups on the aromatic rings are well tolerated by the targeted enzymes when placed at the ortho and para positions; however, they, surprisingly, did not improve metabolic stability in liver microsomes. Our behavioral studies indicate that doses of dual sEH/FAAH inhibitors that alleviate pain do not depress voluntary behavior in naïve rats, which is a common side effect of currently available analgesic drugs (e.g., opioids). Thus, dual sEH/FAAH inhibitors may be a safe and effective approach to treat pain.

[Fatty acid epoxides in the regulation of the inflammation]

Cyclooxygenase and lipoxygenase derived lipid metabolites of polyunsaturated fatty acids (PUFAs), as well as their role in the inflammation, have been studied quite thoroughly. However, cytochrome P450 derived lipid mediators, as well as their participation in the regulation of the inflammation, need deeper understanding. In recent years, it has become known that PUFAs are oxidized by cytochrome P450 epoxygenases to epoxy fatty acids, which act as the extremely powerful lipid mediators involved in resolving inflammation. Recent studies have shown that the anti-inflammatory mechanisms of ω-3 PUFAs are also mediated by their conversion to the endocannabinoid epoxides. Thus, it is clear that a number of therapeutically relevant functions of PUFAs are due to their conversion to PUFA epoxides. However, with the participation of cytochrome P450 epoxygenases, not only PUFA epoxides, but also other metabolites are formed. They are further are converted by epoxide hydrolases into pro-inflammatory dihydroxy fatty acids and anti-inflammatory dihydroxyeicosatrienoic acids. The study of the role of PUFA epoxides in the regulation of the inflammation and pharmacological modeling of the activity of epoxide hydrolases are the promising strategies for the treatment of the inflammatory diseases. This review systematizes the current literature data of the fatty acid epoxides, in particular, the endocannabinoid epoxides. Their role in the regulation of inflammation is discussed.

Enhancing autophagy in Alzheimer's disease through drug repositioning

Alzheimer's disease (AD) is one of the biggest human health threats due to increases in aging of the global population. Unfortunately, drugs for treating AD have been largely ineffective. Interestingly, downregulation of macroautophagy (autophagy) plays an essential role in AD pathogenesis. Therefore, targeting autophagy has drawn considerable attention as a therapeutic approach for the treatment of AD. However, developing new therapeutics is time-consuming and requires huge investments. One of the strategies currently under consideration for many diseases is "drug repositioning" or "drug repurposing". In this comprehensive review, we have provided an overview of the impact of autophagy on AD pathophysiology, reviewed the therapeutics that upregulate autophagy and are currently used in the treatment of other diseases, including cancers, and evaluated their repurposing as a possible treatment option for AD. In addition, we discussed the potential of applying nano-drug delivery to neurodegenerative diseases, such as AD, to overcome the challenge of crossing the blood brain barrier and specifically target molecules/pathways of interest with minimal side effects.

Transdermal Anti-Inflammatory Delivery for Solid Lipid Nanoparticles of Ketoprofen by Microwave-Assisted Microemulsion

PURPOSE

To prepare solid lipid nanopaticles (SLNs) of Ketoprofen (KP) using microwave method. Ketoprofen (KP) is 2-(3-benzolphenyl) propionic acid with anti-inflammatory, analgesic and antipyretic property. The drug has short half-life of 120 mins. It belongs to BCS Class II drug. Gastric irritation is a major limitation for delivery because of acidic nature of the drug. Development of solid lipid nanoparticles with its transdermal drug delivery was the aim of present work.

METHODS

Microwave-assisted microemulsion technique was used for the development of solid lipid nanoparticles. Stearic acid was used as lipid and tween 80 was used as surfactant. By varying the type of lipid and input energy watt, batches were formulated. SLNs were evaluated for zeta potential, drug entrapment, particle size and in-vitro drug release. Crystallinity behaviour was determined by differential scanning calorimetry and powder X-ray diffraction. Anti-inflammatory activity was evaluated for batch M4 of SLNs. The gel was prepared for M4 batch. It was evaluated for viscosity, pH, drug content, in-vitro and ex-vivo diffusion study.

RESULTS

SLN were developed successfully. Based on the size, entrapment efficiency, stability and drug release, batch M4 was selected. SLNs showed 74.8% entrapment efficiency. Forty-fold improvement was observed in the solubility. The particle size was of 682.9 nm and average size of 1047 nm. PDI was 0.685. Zeta potential was -29.5 mV. M4 SLNs batch of gel showed burst release followed by a controlled release for 8 hrs in in-vitro drug release.

CONCLUSION

SLNs were successfully prepared by Microwave-assisted microemulsion technique. SLNs with anti-inflammatory activity was successfully developed with its transdermal delivery.