(E)-β-caryophyllene (BCP) is a bicyclic sesquiterpene widely distributed in the plant kingdom, where it contributes a unique aroma to essential oils and has a pivotal role in the survival and evolution of higher plants. Recent studies provided evidence for protective roles of BCP in animal cells, highlighting its possible use as a novel therapeutic tool. Experimental results show the ability of BCP to reduce pro-inflammatory mediators such as tumor necrosis factor-alfa (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), thus ameliorating chronic pathologies characterized by inflammation and oxidative stress, in particular metabolic and neurological diseases. Through the binding to CB2 cannabinoid receptors and the interaction with members of the family of peroxisome proliferator-activated receptors (PPARs), BCP shows beneficial effects on obesity, non-alcoholic fatty liver disease/nonalcoholic steatohepatitis (NAFLD/NASH) liver diseases, diabetes, cardiovascular diseases, pain and other nervous system disorders. This review describes the current knowledge on the biosynthesis and natural sources of BCP, and reviews its role and mechanisms of action in different inflammation-related metabolic and neurologic disorders.

Squalene (SQ) is a natural triterpene widely distributed in nature. It is a metabolic intermediate of the sterol biosynthetic pathway and represents a possible target in different metabolic and oxidative stress-related disorders. Growing interest has been focused on SQ’s antioxidant properties, derived from its chemical structure. Strong evidence provided by ex vivo models underline its scavenging activity towards free radicals, whereas only a few studies have highlighted its effect in cellular models of oxidative stress. Given the role of unbalanced free radicals in both the onset and progression of several cardiovascular diseases, an in depth evaluation of SQ’s contribution to antioxidant defense mechanisms could represent a strategic approach in dealing with these pathological conditions. At present experimental results overall show a double-edged sword role of squalene in cardiovascular diseases and its function has to be better elucidated in order to establish intervention lines focused on its features. This review aims to summarize current knowledge about endogenous and exogenous sources of SQ and to point out the controversial role of SQ in cardiovascular physiology.

Endothelial function is essential in the maintenance of systemic homeostasis, whose modulation strictly depends on the proper activity of tissue-specific angiocrine factors on the physiopathological mechanisms acting at both single and multi-organ levels. Several angiocrine factors take part in the vascular function itself by modulating vascular tone, inflammatory response, and thrombotic state. Recent evidence has outlined a strong relationship between endothelial factors and gut microbiota-derived molecules. In particular, the direct involvement of trimethylamine N-oxide (TMAO) in the development of endothelial dysfunction and its derived pathological outcomes, such as atherosclerosis, has come to light. Indeed, the role of TMAO in the modulation of factors strictly related to the development of endothelial dysfunction, such as nitric oxide, adhesion molecules (ICAM-1, VCAM-1, and selectins), and IL-6, has been widely accepted. The aim of this review is to present the latest studies that describe a direct role of TMAO in the modulation of angiocrine factors primarily involved in the development of vascular pathologies.

Trimethylamine N-oxide (TMAO) is a diet derived compound directly introduced through foodstuff, or endogenously synthesized from its precursors, primarily choline, L-carnitine, and ergothioneine. New evidence outlines high TMAO plasma concentrations in patients with overt cardiovascular disease, but its direct role in pathological development is still controversial. The purpose of the study was to evaluate the role of TMAO in affecting key intracellular factors involved in endothelial dysfunction development, such as reactive oxygen species, mitochondrial health, calcium balance, and nitric oxide release using bovine aortic endothelial cells (BAE-1). Cell viability and oxidative stress indicators were monitored after acute and prolonged TMAO treatment. The role of TMAO in interfering with the physiological purinergic vasodilatory mechanism after ATP stimulation was defined through measurements of the rise of intracellular calcium, nitric oxide release, and eNOS phosphorylation at Ser1179 (eNOS^Ser1179). TMAO was not cytotoxic for BAE-1 and it did not induce the rise of reactive oxygen species and impairment of mitochondrial membrane potential, either in the basal condition or in the presence of a stressor. In contrast, TMAO modified the purinergic response affecting intracellular ATP-induced calcium increase, nitric oxide release, and eNOS^Ser1179. Results obtained suggest a possible implication of TMAO in impairing the endothelial-dependent vasodilatory mechanism.

Trans-β-caryophyllene (BCP) is a natural sesquiterpene hydrocarbon with several important pharmacological activities, including antioxidant, anti-inflammatory, anticancer, and cardioprotective functions. These properties are mainly due to its selective interaction with the peripherally expressed cannabinoid receptor 2. In addition, BCP activates peroxisome proliferated activator receptors α and γ and inhibits the Toll-like receptor signaling pathway. Given the growing scientific interest in BCP, the aim of our study was to investigate the metabolic effects of a black pepper extract (PipeNig^®-FL), containing a high standardized content of BCP. In particular our interest was focused on its potential activity on lipid accumulation and glucose uptake. The extract PipeNig^®-FL was chemically characterized by gas chromatography–mass spectrometry (GC–MS) and gas chromatography with flame-ionization detection (GC–FID), confirming a high content (814 mg/g) of BCP. Experiments were performed on 3T3-L1 preadipocytes and on C2C12 myotubes. Lipid content following 3T3-L1 adipogenic differentiation was quantified with AdipoRed fluorescence staining. Glucose uptake and GLUT4 membrane translocation were studied in C2C12 myotubes with the fluorescent glucose analog 2-NBDG and by immunofluorescence analysis. Here we show that PipeNig^®-FL reduces 3T3-L1 adipocyte differentiation and lipid accumulation. Moreover, acute exposure of C2C12 myotubes to PipeNig^®-FL improves glucose uptake activity and GLUT4 migration. Taken together, these results reveal interesting and novel properties of BCP, suggesting potential applications in the prevention of lipid accumulation and in the improvement of glucose uptake.

Different gut microbiota-derived metabolites influence cardiovascular function, and, among all, the role of indole-3-propionic acid (IPA), from tryptophan metabolism, shows controversial effects. The aim of this study was to evaluate its role in endothelial dysfunction. IPA effects were studied on bovine aortic endothelial cells (BAE-1). First, IPA cytotoxicity was evaluated by an MTS assay. Then, the levels of intracellular reactive oxygen species (ROS) were evaluated by a microplate reader or fluorescence microscopy with the CellROX^® Green probe, and nitric oxide (NO) production was studied by fluorescence microscopy with the DAR4M-AM probe after acute or chronic treatment. Finally, immunoblotting analysis for endothelial nitric oxide synthase (eNOS) phosphorylation (p-eNOS) was performed. In BAE-1, IPA was not cytotoxic, except for the highest concentration (5 mM) after 48 h of treatment, and it showed neither oxidant nor antioxidant activity. However, the physiological concentration of IPA (1 μM) significantly reduced NO released by adenosine triphosphate (ATP)-stimulated BAE-1. These last data were confirmed by Western blot analysis, where IPA induced a significant reduction in p-eNOS in purinergic-stimulated BAE-1. Given these data, we can speculate that IPA negatively affects the physiological control of vascular tone by impairing the endothelial NO release induced by purinergic stimulation. These results represent a starting point for understanding the mechanisms underlying the relationship between gut microbiota metabolites and cardiometabolic health.