Seven undescribed meroterpenoids, peniscmeroterpenoids A - G, were isolated from the marine-derived fungus Penicillium sclerotiorum GZU-XW03-2. Their structures were established by the spectroscopic methods and the electronic circular dichroism (ECD) calculations. Peniscmeroterpenoid A possessed an unprecedented and highly oxidized 6/7/6/5/5 pentacyclic system, featuring a unique tetrahydrofuro [2,3-b]furan-2(3H)-one motif. Peniscmeroterpenoids B - E owned rare 6(D)/5(E) fused rings were not common in natural products, and peniscmeroterpenoid E is the first example of a berkeleyone analogue stripped of the methyl ester fragment. In bioassays, peniscmeroterpenoids A and D inhibited the production of nitric oxide (NO) in RAW264.7 cells with IC50 values of 26.60 ± 1.15 and 8.79 ± 1.22 μM. Moreover, peniscmeroterpenoid D significantly suppressed the production of pro-inflammatory mediators (COX-2, IL-1β and IL-6) and the protein expression of the enzyme iNOS.

Alcohol consumption is associated with gut dysbiosis, increased intestinal permeability, endotoxemia, and a cascade that leads to persistent systemic inflammation, alcoholic liver disease, and other ailments. Craving for alcohol and its consequences depends, among other things, on the endocannabinoid system. We have analyzed the relative role of central vs. peripheral cannabinoid CB1 receptors (CB1R) using a \"two-bottle\" as well as a \"drinking in the dark\" paradigm in mice. The globally acting CB1R antagonist rimonabant and the non-brain penetrant CB1R antagonist JD5037 inhibited voluntary alcohol intake upon systemic but not upon intracerebroventricular administration in doses that elicited anxiogenic-like behavior and blocked CB1R-induced hypothermia and catalepsy. The peripherally restricted hybrid CB1R antagonist/iNOS inhibitor S-MRI-1867 was also effective in reducing alcohol consumption after oral gavage, while its R enantiomer (CB1R inactive/iNOS inhibitor) was not. The two MRI-1867 enantiomers were equally effective in inhibiting an alcohol-induced increase in portal blood endotoxin concentration that was caused by increased gut permeability. We conclude that (i) activation of peripheral CB1R plays a dominant role in promoting alcohol intake and (ii) the iNOS inhibitory function of MRI-1867 helps in mitigating the alcohol-induced increase in endotoxemia.

Nine previously undescribed butyrolactone and sesquiterpene derivatives, named cyclopentanone A (1), subamolides F and G (2 and 3), secosubamolide F (4), rupestonic acids J - L (5-7), linderaguaianols A and B (8 and 9), together with six known ones 10-15 were isolated from the roots of Lindera glauca. Their structures, including their absolute configurations were elucidated by extensive spectroscopic analysis, quantum chemical calculations, and Mo2(AcO)4-induced circular dichroism. Compound 1 that possessed a unique five-membered cyclopentane skeleton with a side chain was rarely found from natural sources. The biogenetic pathway for 1-4 was postulated. Secosubamolide F (4) inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-activated RAW264.7 cells with IC50 value of 1.73 ± 0.18 μM and also significantly suppressed the production of iNOS. The binding interactions between 4 and iNOS were investigated using docking analyses.

COVID-19 (SARS-CoV-2) causes multiple inflammatory complications, resulting not only in severe lung inflammation but also harm to other organs. Although the current focus is on the management of acute COVID-19, there is growing concern about long-term effects of COVID-19 (Long Covid), such as fibroproliferative changes in the lung, heart and kidney. Therefore, the identification of therapeutic targets not only for the management of acute COVID-19 but also for preventing Long Covid are needed, and would mitigate against long-lasting health burden and economic costs, in addition to saving lives. COVID-19 induces pathological changes via multiple pathways, which could be targeted simultaneously for optimal effect. We discuss the potential pathologic function of increased activity of the endocannabinoid/CB1 receptor system and inducible NO synthase (iNOS). We advocate a polypharmacology approach, wherein a single chemical entity simultaneously interacts with CB1 receptors and iNOS causing inhibition, as a potential therapeutic strategy for COVID-19-related health complications.

Neurodegenerative diseases are associated with increased levels of nitric oxide (NO) mainly produced by microglial cells through inducible nitric oxide synthase (iNOS) whose expression is induced by inflammatory stimuli. NO can both exert cytotoxic functions and induce a metabolic switch by inhibiting oxidative phosphorylation and upregulating glycolytic flux. Here, we investigated whether two newly synthesized acetamidine based iNOS inhibitors, namely CM292 and CM544, could inhibit lipopolysaccharide (LPS)-induced BV2 microglial cell activation, focusing on both inflammatory and metabolic profiles. We found that CM292 and CM544, without affecting iNOS protein expression, reduced NO production and reverted LPS-induced inflammatory and cytotoxic response. Furthermore, in the presence of the inflammatory stimulus, both the inhibitors increased the expression of glycolytic enzymes. In particular, CM292 significantly reduced nuclear accumulation of pyruvate kinase M2, increased mitochondrial membrane potential and oxygen consumption rate, and augmented the expression of pyruvate dehydrogenase, pointing to a metabolic switch toward oxidative phosphorylation. These data confirm the role played by NO in the connection between cell bioenergetics profile and inflammation, and suggest the potential usefulness of iNOS inhibitors in redirecting microglia from detrimental to pro-regenerative phenotype.

Accumulating evidence suggests that inflammation has a key role in the pathogenesis of osteoarthritis (OA). Nitric oxide (NO) has been established as one of the major inflammatory mediators in OA and drives many pathological changes during the development and progression of OA. Excessive production of NO in chondrocytes promotes cartilage destruction and cellular injury. The synthesis of NO in chondrocytes is catalyzed by inducible NO synthase (iNOS), which is thereby an attractive therapeutic target for the treatment of OA. A number of direct and indirect iNOS inhibitors, bioactive compounds, and plant-derived small molecules have been shown to exhibit chondroprotective effects by suppressing the expression of iNOS. Many of these iNOS inhibitors hold promise for the development of new, disease-modifying therapies for OA; however, attempts to demonstrate their success in clinical trials are not yet successful. Many plant extracts and plant-derived small molecules have also shown promise in animal models of OA, though further studies are needed in human clinical trials to confirm their therapeutic potential. In this review, we discuss the role of iNOS in OA pathology and the effects of various iNOS inhibitors in OA.

Nitric oxide synthases (NOS) are a family of isoforms, which generate nitric oxide (NO). NO is one of the smallest molecules in nature and acts mainly as a potent vasodilator. It participates in various biological processes ranging from physiological to pathological conditions. Inducible NOS (iNOS, NOS2) is a calcium-independent and inducible isoform. Despite high iNOS expression in many tumors, the role of iNOS is still unclear and complex with both enhancing and prohibiting actions in tumorigenesis. Nature presents a broad variety of natural stimulators and inhibitors, which may either promote or inhibit iNOS response. In the present review, we give an overview of iNOS-modulating agents with a special focus on both natural and synthetic molecules and their effects in related biological processes. The role of iNOS in physiological and pathological conditions is also discussed.

A series of clovamide analogues, namely, 1a-13a and 1b-13b, was synthesized and evaluated for their anti-neuroinflammatory activities using BV-2 microglia cells. Among these compounds, six (1b, 4b-8b) showed NO inhibition with no or weak cytotoxicity (CC50 > 100 μM), especially 4b, and showed an IC50 value of 2.67 μM. Enzyme activity and docking assay revealed that the six compounds, especially 4b, target inducible NO synthase (iNOS) and exhibit potent inhibitory effects on iNOS with IC50 values ranging from 1.01 μM to 29.23 μM 4b significantly suppressed the expression of pro-inflammatory cytokines in lipopolysaccharide-stimulated cells. Notably, the oral administration of 4b remarkably improved dyskinesia, reduced the expression of glial fibrillary acidic protein (GFAP)-a marker of neuroinflammation, and increased tyrosine hydroxylase-positive cells in 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridine-induced Parkinson\'s disease (PD) mouse models. These observations demonstrated that 4b is an effective and promising candidate for PD therapy.

OBJECTIVE: Shock wave lithotripsy treatment (SWT) is not completely free from side effects; one of the accused mechanisms for renal injury during SWT is oxygen- and nitrogen-derived free radical productions. Therefore, we aimed to evaluate the effect of inhibition of nitric oxide (NO) production by N-[3(aminomethyl) benzyl) acetamidine] (1400W), highly selective inducible nitric oxide synthase (iNOS) inhibitor, at SWT-induced kidney damage.
METHODS: Twenty-four rats those underwent right nephrectomy procedure were divided equally into three groups as control, SWT, and SWT + 1400W. 1400W was administered at a dose of 10 mg/kg at 2 h prior to SWT procedure and at the beginning of SWT procedure via intraperitoneal route and continued daily for consecutive 3 days. At the end of the fourth day, animals were killed via decapitation and trunk blood and the left kidneys were taken for biochemical and histopathologic evaluation.
RESULTS: SWT caused renal tubular damage and increased lipid peroxidation and antioxidant enzyme activities and SWT also significantly increased nitro-oxidative products. Inhibition of iNOS via administration of 1400W ameliorated renal injury and decreased tissue lipid peroxidation (malondialdehyde), superoxide dismutase, glutathione peroxidase and nitrite/nitrate levels (NOx). In addition, it was seen that histolopathological changes were attenuated in the SWT + 1400W group when compared to SWT group.
CONCLUSIONS: SWT-induced renal injury might be due to excessive production of oxygen free radicals and NO production. Inhibition of iNOS attenuates renal injury following SWT treatment. It can be concluded that iNOS inhibitors or peroxynitrite scavengers might be used to protect the kidneys against SWT-induced morphological and functional injuries.

Inducible Nitric Oxide Synthase (iNOS) has been involved in a variety of diseases, and thus it is interesting to discover and optimize new iNOS inhibitors. In previous studies, a series of benzimidazole-quinolinone derivatives with high inhibitory activity against human iNOS were discovered. In this work, three-dimensional quantitative structure-activity relationships (3D-QSAR), molecular docking and molecular dynamics (MD) simulation approaches were applied to investigate the functionalities of active molecular interaction between these active ligands and iNOS. A QSAR model with R(2) of 0.9356, Q(2) of 0.8373 and Pearson-R value of 0.9406 was constructed, which presents a good predictive ability in both internal and external validation. Furthermore, a combined analysis incorporating the obtained model and the MD results indicates: (1) compounds with the proper-size hydrophobic substituents at position 3 in ring-C (R(3) substituent), hydrophilic substituents near the X(6) of ring-D and hydrophilic or H-bond acceptor groups at position 2 in ring-B show enhanced biological activities; (2) Met368, Trp366, Gly365, Tyr367, Phe363, Pro344, Gln257, Val346, Asn364, Met349, Thr370, Glu371 and Tyr485 are key amino acids in the active pocket, and activities of iNOS inhibitors are consistent with their capability to alter the position of these important residues, especially Glu371 and Thr370. The results provide a set of useful guidelines for the rational design of novel iNOS inhibitors.