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The omega-3 fatty acid ethanolamides, docosahexaenoyl ethanolamide (DHEA) and eicosapentaenoyl ethanolamide (EPEA), displayed greater anti-proliferative potency than their parent omega-3 fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), in LNCaP and PC3 prostate cancer cells. DHEA and EPEA activated cannabinoid CB(1) and CB(2) receptors in vitro with significant potency, suggesting that they are endocannabinoids. Both LNCaP and PC3 cells expressed CB(1) and CB(2) receptors, and the CB(1)- and CB(2)-selective antagonists, AM281 and AM630, administered separately or together, reduced the anti-proliferative potencies of EPEA and EPA but not of DHEA or DHA in PC3 cells and of EPA but not of EPEA, DHEA or DHA in LNCaP cells. Even so, EPEA and EPA may not have inhibited PC3 or LNCaP cell proliferation via cannabinoid receptors since the anti-proliferative potency of EPEA was well below the potency it displayed as a CB(1) or CB(2) receptor agonist. Indeed, these receptors may mediate a protective effect because the anti-proliferative potency of DHEA in LNCaP and PC3 cells was increased by separate or combined administration of AM281 and AM630. The anandamide-metabolizing enzyme, fatty acid amide hydrolase (FAAH), was highly expressed in LNCaP but not PC3 cells. Evidence was obtained that FAAH metabolizes EPEA and DHEA and that the anti-proliferative potencies of these ethanolamides in LNCaP cells can be enhanced by inhibiting this enzyme. Our findings suggest that the expression of cannabinoid receptors and of FAAH in some tumour cells could well influence the effectiveness of DHA and EPA or their ethanolamide derivatives as anticancer agents.

Antibiotic resistance is a serious public health problem throughout the world. Overcoming methicillin and multidrug-resistant Staphylococcus aureus (MRSA/MDRSA) infections has become a challenge and there is an urgent need for new therapeutic approaches. We have previously demonstrated that the endocannabinoid Anandamide (AEA) can sensitize MRSA to antibiotics. Here we have studied the mechanism of action using a MDRSA clinical isolate that are sensitized by AEA to methicillin and norfloxacin. We found that AEA treatment halts the growth of both antibiotic-sensitive and antibiotic-resistant S. aureus. The AEA-treated bacteria become elongated and the membranes become ruffled with many protrusions. AEA treatment also leads to an increase in the percentage of bacteria having a complete septum, suggesting that the cell division is halted at this stage. The latter is supported by cell cycle analysis that shows an accumulation of bacteria in the G2/M phase after AEA treatment. We further observed that AEA causes a dose-dependent membrane depolarization that is partly relieved upon time. Nile red staining of the bacterial membranes indicates that AEA alters the membrane structures. Importantly, 4′-6-diamidino-2-phenylindole (DAPI) accumulation assay and ethidium bromide efflux (EtBr) assay unveiled that AEA leads to a dose-dependent drug accumulation by inhibiting drug efflux. In conclusion, our study demonstrates that AEA interferes with cell division, alters the membrane properties of MDRSA, and leads to increased intracellular drug retention, which can contribute to the sensitization of MDRSA to antibiotics.

Bone mass is determined by a continuous remodeling process, whereby the mineralized matrix is being removed by osteoclasts and subsequently replaced with newly formed bone tissue produced by osteoblasts. Here we report the presence of endogenous amides of long-chain fatty acids with amino acids or with ethanolamine (N-acyl amides) in mouse bone. Of these compounds, N-oleoyl-L-serine (OS) had the highest activity in an osteoblast proliferation assay. In these cells, OS triggers a Gi-protein-coupled receptor and Erk1/2. It also mitigates osteoclast number by promoting osteoclast apoptosis through the inhibition of Erk1/2 phosphorylation and receptor activator of nuclear-κB ligand (RANKL) expression in bone marrow stromal cells and osteoblasts. In intact mice, OS moderately increases bone volume density mainly by inhibiting bone resorption. However, in a mouse ovariectomy (OVX) model for osteoporosis, OS effectively rescues bone loss by increasing bone formation and markedly restraining bone resorption. The differential effect of exogenous OS in the OVX vs. intact animals is apparently a result of an OVX-induced decrease in skeletal OS levels. These data show that OS is a previously unexplored lipid regulator of bone remodeling. It represents a lead to antiosteoporotic drug discovery, advantageous to currently available therapies, which are essentially either proformative or antiresorptive.fatty acyl amides I n mammals, including humans, bone mass is determined by an unremitting remodeling process whereby the mineralized matrix is continuously removed by osteoclasts and subsequently replaced with newly formed bone tissue produced by osteoblasts. This process is regulated by autocrine/paracrine factors, such as receptor activator of nuclear-κB ligand (RANKL), osteoprotegerin (OPG), bone morphogenetic proteins, and Wnt, as well as circulating hormones (e.g., sex steroids, parathyroid hormone) and brain-derived signals (e.g., sympathetic, pituitary) (1-3). Imbalanced bone remodeling leads to skeletal pathologies, mainly osteoporosis, the most common degenerative disorder in affluent societies, which results from a net increase in bone resorption (4). Identification of endogenous constituents, which regulate bone remodeling and skeletal mass, contributes to the elucidation of the mechanisms involved in this process and offers promise for developing novel antiosteoporotic pharmacotherapy.Amides of long-chain fatty acids with amino acids or with ethanolamine (N-acyl amides) represent a major group of endogenous lipids. In mammalian tissues they have numerous physiological functions. For example, anandamide (arachidonoyl ethanolamide) is the first identified endogenous psychoactive ligand of cannabinoid receptors (5); arachidonoyl serine is an endogenous vasodilator, which does not bind to the cannabinoid receptors (6); and oleoyl ethanolamide is an endogenous structural analog to anandamide that regulates food intake through the activation of GPR 119 (7, 8). The well-established biosynthetic tendency to follow existing p...

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Infections caused by antibiotic-resistant strains of Staphylococcus aureus have reached epidemic proportions globally. Staphylococcal biofilms are associated with increased antimicrobial resistance and are generally less affected by host immune factors. Therefore, there is an urgent need for novel agents that not only aim at multidrug-resistant pathogens, but also ones that will act as anti biofilms. In the present study, we investigated the antimicrobial activity of the endocannabinoid (EC) anandamide (AEA) and the endocannabinoid-like (EC-like), arachidonoyl serine (AraS) against methicillin resistant S. aureus strains (MRSA). We observed a strong inhibition of biofilm formation of all tested MRSA strains as well as a notable reduction of metabolic activity of pre-formed MRSA biofilms by both agents. Moreover, staphylococcal biofilm-associated virulence determinants such as hydrophobicity, cell aggregation and spreading ability were altered by AEA and AraS. In addition, the agents were able to modify bacterial membrane potential. Importantly, both compounds prevent biofilm formation by altering the surface of the cell without killing the bacteria. Therefore, we propose that EC and EC-like compounds may act as a natural line of defence against MRSA or other antibiotic resistant bacteria. Due to their anti biofilm action these agents could also be a promising alternative to antibiotic therapeutics against biofilm-associated MRSA infections.

Activation of the CB2 receptor is apparently an endogenous protective mechanism. Thus, it restrains inflammation and protects the skeleton against age-related bone loss. However, the endogenous cannabinoids, as well as Δ(9)-tetrahydrocannabinol, the main plant psychoactive constituent, activate both cannabinoid receptors, CB1 and CB2. HU-308 was among the first synthetic, selective CB2 agonists. HU-308 is antiosteoporotic and antiinflammatory. Here we show that the HU-308 enantiomer, designated HU-433, is 3-4 orders of magnitude more potent in osteoblast proliferation and osteoclast differentiation culture systems, as well as in mouse models, for the rescue of ovariectomy-induced bone loss and ear inflammation. HU-433 retains the HU-308 specificity for CB2, as shown by its failure to bind to the CB1 cannabinoid receptor, and has no activity in CB2-deficient cells and animals. Surprisingly, the CB2 binding affinity of HU-433 in terms of [(3)H]CP55,940 displacement and its effect on [(35)S]GTPγS accumulation is substantially lower compared with HU-308. A molecular-modeling analysis suggests that HU-433 and -308 have two different binding conformations within CB2, with one of them possibly responsible for the affinity difference, involving [(35)S]GTPγS and cAMP synthesis. Hence, different ligands may have different orientations relative to the same binding site. This situation questions the usefulness of universal radioligands for comparative binding studies. Moreover, orientation-targeted ligands have promising potential for the pharmacological activation of distinct processes.

A novel photo protective mycosporine was isolated from the lichenized ascomycete Collema cristatum. Biological activity was measured in terms of protection against UV‐B induced membrane destruction and pyrimidine dimer formation in cultured human keratinocytes, and prevention of UV‐B induced erythema. It was found that the pure isolated compound prevented UV‐B induced cell destruction in a dose‐dependent manner, that the compound partially prevented pyrimidine dimer formation and completely prevented UV‐B induced erythema when applied to the skin prior to irradiation.