Phenotypic screen identifies the natural product silymarin as a novel anti-inflammatory analgesic

Physiological profiling of cannabidiol reveals profound inhibition of sensory neurons

ABSTRACT

Cannabidiol (CBD), the main nonpsychoactive cannabinoid of cannabis, holds promise for nonaddictive treatment of pain. Although preclinical studies have been encouraging, well-controlled human trials have been largely unsuccessful. To investigate this dichotomy and better understand the actions of CBD, we used high-content calcium imaging with automated liquid handling and observed broad inhibition of neuronal activation by a host of ionotropic and metabotropic receptors, including transient receptor potential (Trp) and purinergic receptors, as well as mediators of intracellular calcium cycling. To assess the effect of CBD on overall nociceptor electrical activity, we combined the light-activated ion channel channelrhodposin in TRPV1-positive nociceptors and a red-shifted calcium indicator and found that 1 µM CBD profoundly increased the optical threshold for calcium flux activation. Experiments using traditional whole-cell patch-clamp showed increase of nociceptor activation threshold at submicromolar concentrations, but with unusually slow kinetics, as well as block of voltage-activated currents. To address a more integrated capacity of CBD to influence nociceptor sensitization, a process implicated in multiple pain states, we found that submicromolar concentrations of CBD inhibited sensitization by the chemotherapeutic drug vincristine. Taken together, these results demonstrate that CBD can reduce neuronal activity evoked by a strikingly wide range of stimuli implicated in pain signaling. The extensive effects underscore the need for further studies at substantially lower drug concentrations, which are more likely to reflect physiologically relevant mechanisms. The slow kinetics and block raise biophysical questions regarding the lipophilic properties of CBD and its action on channels and receptors within membranes.

Recent advances of phenotypic screening strategies in the application of anti-influenza virus drug discovery

Seasonal and pandemic influenza virus infections not only pose a serious threat to human health but also cause tremendous economic losses and social burdens. However, due to the inherent high variability of influenza virus RNA genomes, the existing anti-influenza virus drugs have been frequently faced with the clinical issue of emerging drug-resistant mutants. Therefore, there is an urgent need to develop efficient and broad-spectrum antiviral agents against wild-type and drug-resistant mutant strains. Phenotypic screening has been widely employed as a reliable strategy to evaluate antiviral efficacy of novel agents independent of their modes of action, either directly targeting viral proteins or regulating cellular factors involved in the virus life cycle. Here, from the point of view of medicinal chemistry, we review the research progress of phenotypic screening strategies by focusing direct acting antivirals against influenza virus. It could provide scientific insights into discovery of a distinctive class of therapeutic candidates that ensure high efficiency but low cytotoxicity, and address issues from circulation of drug-resistant influenza viruses in the future.

Silymarin and Inflammation: Food for Thoughts

Inflammation is a vital defense mechanism, creating hostile conditions for pathogens, preventing the spread of tissue infection and repairing damaged tissues in humans and animals. However, when inflammation resolution is delayed or compromised as a result of its misregulation, the process proceeds from the acute phase to chronic inflammation, leading to the development of various chronic illnesses. It is proven that redox balance disturbances and oxidative stress are among major factors inducing NF-κB and leading to over-inflammation. Therefore, the anti-inflammatory properties of various natural antioxidants have been widely tested in various in vitro and in vivo systems. Accumulating evidence indicates that silymarin (SM) and its main constituent silibinin/silybin (SB) have great potential as an anti-inflammation agent. The main anti-inflammatory mechanism of SM/SB action is attributed to the inhibition of TLR4/NF-κB-mediated signaling pathways and the downregulated expression of pro-inflammatory mediators, including TNF-α, IL-1β, IL-6, IL-12, IL-23, CCL4, CXCL10, etc. Of note, in the same model systems, SM/SB was able to upregulate anti-inflammatory cytokines (IL-4, IL-10, IL-13, TGF-β, etc.) and lipid mediators involved in the resolution of inflammation. The inflammatory properties of SM/SB were clearly demonstrated in model systems based on immune (macrophages and monocytes) and non-immune (epithelial, skin, bone, connective tissue and cancer) cells. At the same time, the anti-inflammatory action of SM/SB was confirmed in a number of in vivo models, including toxicity models, nonalcoholic fatty liver disease, ischemia/reperfusion models, stress-induced injuries, ageing and exercising models, wound healing and many other relevant model systems. It seems likely that the anti-inflammatory activities of SM/SB are key elements on the health-promoting properties of these phytochemicals.

Efficacy and Mechanisms of Silybum Marianum, Silymarin, and Silibinin on Rheumatoid Arthritis and Osteoarthritis Symptoms: A Systematic Review

BACKGROUND

Rheumatoid arthritis (RA) and osteoarthritis (OA) are the most common forms of skeletal disease worldwide.

OBJECTIVE

The current systematic review investigated the mechanisms of Silybum marianum, silymarin, and silibinin on RA and OA symptoms.

METHODS

The PRISMA 2020 statement was used for reporting Items in this systematic review. The result was a list of five databases, including Web of Science, Cochrane Library, Embase, PubMed, and Scopus. After determining the inclusion and exclusion criteria, of 437 records identified, 21 studies were eligible. The data were extracted from the studies and imported into an Excel form, and finally, the effects, outcomes, and associated mechanisms were surveyed.

RESULTS

Silybum marianum and its main constituents revealed immunomodulatory, anti-inflammatory, antioxidant, and anti-apoptotic properties in humans and laboratory animals. Moreover, they protect the joints against the cartilage matrix's hypocellularity and fibrillation, reduce synovitis, and inhibit degeneration of aggrecan and collagen-II in human chondrocytes. They also, through reducing inflammatory cytokines, show an analgesic effect. Although silymarin and silibinin have low absorption, their bioavailability can be increased with nanoparticles.

CONCLUSION

In experimental studies, Silybum marianum, silymarin, and silibinin revealed promising effects on RA and OA symptoms. However, more clinical studies are needed in this field to obtain reliable results and clinical administration of these compounds.

Preventive and Therapeutic Effects of Silybum marianum Seed Extract Rich in Silydianin and Silychristin in a Rat Model of Metabolic Syndrome

Metabolic syndrome (MetS) has become an increasing global health problem, which leads to cardiovascular diseases and type 2 diabetes. Silybum marianum extracts have been reported to possess several biological activities. In this study, an ethyl acetate extract prepared from S. marianum seeds of the Iraqi Kurdistan region was analyzed to identify its chemical constituents. Subsequently, its potential for the prevention and treatment of MetS was studied in a rat model induced by a high-fat/high-fructose diet (HFD/F). Silydianin and silychristin were the most abundant flavonolignan constituents (39.4%) identified in the S. marianum extract (SMEE). HFD/F-induced rats treated with SMEE exhibited preventive effects including reduced serum triglyceride levels (TG), decreased glucose levels in an oral glucose tolerance test (p < 0.001), attenuated weight gain, and reduced blood pressure compared to the untreated control group. Therapeutic application of SMEE after inducing MetS led to lowering of TG (p < 0.001) and glucose levels, in addition to reducing weight gain and normalizing blood pressure (p < 0.005). Thus, S. marianum extract rich in silydianin and silychristin may be useful for preventing and attenuating MetS, and further research and clinical trials are warranted.

Sphingosine 1-phosphate signaling during infection and immunity

Sphingolipids are essential components of all eukaryotic membranes. The bioactive sphingolipid molecule, Sphingosine 1-Phosphate (S1P), regulates various important biological functions. This review aims to provide a comprehensive overview of the role of S1P signaling pathway in various immune cell functions under different pathophysiological conditions including bacterial and viral infections, autoimmune disorders, inflammation, and cancer. We covered the aspects of S1P pathways in NOD/TLR pathways, bacterial and viral infections, autoimmune disorders, and tumor immunology. This implies that targeting S1P signaling can be used as a strategy to block these pathologies. Our current understanding of targeting various components of S1P signaling for therapeutic purposes and the present status of S1P pathway inhibitors or modulators in disease conditions where the host immune system plays a pivotal role is the primary focus of this review.