Paracetamol (acetaminophen) is the most commonly used over‐the‐counter (OTC) drug in the world. Despite its popularity and use for many years, the safety of its application and its mechanism of action are still unclear. Currently, it is believed that paracetamol is a multidirectional drug and at least several metabolic pathways are involved in its analgesic and antipyretic action. The mechanism of paracetamol action consists in inhibition of cyclooxygenases (COX‐1, COX‐2, and COX‐3) and involvement in the endocannabinoid system and serotonergic pathways. Additionally, paracetamol influences transient receptor potential (TRP) channels and voltage‐gated Kv7 potassium channels and inhibits T‐type Cav3.2 calcium channels. It also exerts an impact on L‐arginine in the nitric oxide (NO) synthesis pathway. However, not all of these effects have been clearly confirmed. Therefore, the aim of our paper was to summarize the current state of knowledge of the mechanism of paracetamol action with special attention to its safety concerns.

The Inonotus obliquus (I. obliquus) mushroom was traditionally used to treat various gastrointestinal diseases. For many years, mounting evidence has indicated the potential of I. obliquus extracts for treatment of viral and parasitic infections. Furthermore, substances from I. obiquus have been shown to stimulate the immune system. The most promising finding was the demonstration that I. obliquus has hypoglycemic and insulin sensitivity potential. This review summarizes the therapeutic potential of I. obliquus extracts in counteracting the progression of cancers and diabetes mellitus as well as their antiviral and antiparasitic activities and antioxidant role. As shown by literature data, various authors have tried to determine the molecular mechanism of action of I. obliquus extracts. Two mechanisms of action of I. obliquus extracts are currently emerging. The first is associated with the broad-sense impact on antioxidant enzymes and the level of reactive oxygen species (ROS). The other is related to peroxisome proliferator-activated receptor gamma (PPARγ) effects. This receptor may be a key factor in the anti-inflammatory, antioxidant, and anti-cancer activity of I. obliquus extracts. It can be concluded that I. obliquus fits the definition of functional food and has a potentially positive effect on health beyond basic nutrition; however, studies that meet the evidence-based medicine (EBM) criteria are needed.

The products of elastin degradation, namely elastin-derived peptides (EDPs), are detectable in the cerebrospinal fluid of healthy individuals and in patients after ischemic stroke, and their number increases with age. Depending on their concentrations, both nitric oxide (NO) and reactive oxygen species (ROS) take part either in myocardial ischemia reperfusion injury or in neurovascular protection after ischemic stroke. The aim of our study was to determine the impact of VGVAPG peptide on ROS and NO production and expression of endothelial nitric oxide synthase (eNos), inducible nitric oxide synthase (iNos) and neuronal nitric oxide synthase (nNos) in mouse cortical astrocytes in vitro. Primary astrocytes were maintained in DMEM/F12 without phenol red supplemented with 10% fetal bovine serum. The cells were exposed to rising VGVAPG peptide concentrations, and ROS and NO production was measured. After 6 h (for mRNA) and 24 (for the protein) of exposure to 10 nM and 1 µM of the peptide, expression of nNos, iNos and eNos was measured. Moreover, the Glb1 siRNA gene knockdown method and Pioglitazone, a peroxisome proliferator-activated receptor gamma (Pparγ) agonist, were applied. Our study shows that the VGVAPG peptide decreased eNos, iNos and nNos mRNA and protein expression in mouse astrocytes in vitro. The VGVAPG peptide also decreased NO production while increasing ROS production in the cells. Furthermore, silencing of the Glb1 gene reversed all effects caused by the VGVAPG peptide. However, due to the lack of sufficient data explaining the molecular mechanism of action of the VGVAPG peptide in the nervous system, more studies in this area are necessary.

Elastin is a highly elastic protein present in connective tissue. As a result of protease activity, elastin hydrolysis occurs, and during this process, elastin-derived peptides (EDPs) are released. One of the constitutively repeating elastin and EDP building sequences is the hexapeptide VGVAPG. Therefore, the aim of our research was to define the effect of VGVAPG peptide on adipogenesis in a mouse 3T3-L1 cell line. 3T3-L1 cells were differentiated according to a previously described protocol and exposed to increasing concentrations of VGVAPG or VVGPGA peptide. The obtained results showed that VGVAPG peptide does not stimulate reactive oxygen species (ROS) production, caspase-1 activation, and 3T3-L1 cell proliferation. In the second part of the experiments, it was proved that VGVAPG peptide decreased lipid accumulation as measured by oil red O staining, which was confirmed by the profile of increased expression markers of undifferentiated preadipocytes. In our experiments, 10 nM VGVAPG added for differentiating to adipocytes increased the expression of Pref-1, serpin E1, and adiponectin as compared to rosiglitazone (PPARγ agonist)-treated group and simultaneously decreased the expression of VEGF and resistin as compared to the rosiglitazone-treated group. The obtained results show that VGVAPG peptide sustains 3T3 cells in undifferentiated state. Abbreviations: DMSO: dimethyl sulphoxide; EBP: elastin-binding protein; EDPs: elastin-derived peptides; FBS: foetal bovine serum; Glb1: gene for beta-galactosidase; LDL: low-density-lipoprotein; PAI-1 (Serpin E1): plasminogen activator inhibitor-1; PBS: phosphate-buffered saline; PPARγ: peroxisome proliferator-activated receptor gamma; Pref-1: preadipocyte factor 1; ROS: reactive oxygen species; VEGF-A: vascular endothelial growth factor-A; VGVAPG: Val-Gly-Val-Ala-Pro-Gly; β-Gal: beta-galactosidase; ORO: oil red O; IBMX: 3-isobutyl-1-methylxanthine; H₂DCFDA: 2ʹ,7ʹ-dichlorodihydrofluorescein diacetate; DMEM: Dulbecco’s Modified Eagle’s Medium; VVGPGA: Val-Val-Gly-Pro-Gly-Ala.

Nowadays, diabetes mellitus type 2 (T2DM) is a serious problem in western European societies and in the United States. Thiazolidinediones (TZDs) are a broad group of compounds used to decrease insulin resistance in TDM2. To date, it has been believed that TZDs act mainly through activation of peroxisome proliferator-activated receptor gamma (PPARγ). The PPARγ receptor is important in differentiation of preadipocytes into mature adipocytes. Therefore, given the potential of structurally related thiopyrano[2,3-d]thiazoles Les-2194 and Les-3377 and 4-thiazolidinone derivative Les-3640 to interact with the PPARγ receptor, the aim of the present study was to evaluate the impact of the 4-thiazolidinone-based derivatives mentioned above on the process of 3T3-L1 cell line differentiation into adipocytes. In the first part of our study, we prove that Les-2194, Les-3377, and Les-3640 are cytotoxic to 3T3-L1 cells. In the next stage, we determine that Les-2194, Les-3377, and Les-3640 stimulate lipid accumulation (using the ORO staining method) and induce specific gene expression (Dlk1, Fabp4, Vegfa, Pai-1, Resistin, Adiponectin, and Pparγ). Our data show that rosiglitazone, pioglitazone, Les-2194, and Les-3640 at a concentration of 2 μM do not affect 3T3-L1 cell viability and do not activate the apoptotic process. Only Les-3377 decreased the number and metabolism of the cells. Although all the studied compounds influenced the expression of Dlk1, Fabp4, Vegfa, Pai-1, Resistin, Adiponectin, and Pparγ genes, none of them caused gene expression similar to that induced by rosiglitazone or pioglitazone. The ORO staining showed that rosiglitazone and pioglitazone induced lipid accumulation in the 3T3-L1 cell line, which is a marker of mature adipocytes. Only rosiglitazone increased Pparγ protein expression after 14 days of differentiation.