Cannabis sativa and the endogenous cannabinoid system: therapeutic potential for appetite regulation

The herb Cannabis sativa (C. sativa) has been used in China and on the Indian subcontinent for thousands of years as a medicine. However, since it was brought to the UK and then the rest of the western world in the late 19th century, its use has been a source of controversy. Indeed, its psychotropic side effects are well reported but only relatively recently has scientific endeavour begun to find valuable uses for either the whole plant or its individual components. Here, we discuss evidence describing the endocannabinoid system, its endogenous and exogenous ligands and their varied effects on feeding cycles and meal patterns. Furthermore we also critically consider the mounting evidence which suggests non‐tetrahydrocannabinol phytocannabinoids play a vital role in C. sativa‐induced feeding pattern changes. Indeed, given the wide range of phytocannabinoids present in C. sativa and their equally wide range of intra‐, inter‐ and extra‐cellular mechanisms of action, we demonstrate that non‐Δ9tetrahydrocannabinol phytocannabinoids retain an important and, as yet, untapped clinical potential

Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR Cascade Inhibitors: How Mutations Can Result in Therapy Resistance and How to Overcome Resistance

The Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades are often activated by genetic alterations in upstream signaling molecules such as receptor tyrosine kinases (RTK). Integral components of these pathways, Ras, B-Raf, PI3K, and PTEN are also activated/inactivated by mutations. These pathways have profound effects on proliferative, apoptotic and differentiation pathways. Dysregulation of these pathways can contribute to chemotherapeutic drug resistance, proliferation of cancer initiating cells (CICs) and premature aging. This review will evaluate more recently described potential uses of MEK, PI3K, Akt and mTOR inhibitors in the proliferation of malignant cells, suppression of CICs, cellular senescence and prevention of aging. Ras/Raf/MEK/ERK and Ras/PI3K/PTEN/Akt/mTOR pathways play key roles in the regulation of normal and malignant cell growth. Inhibitors targeting these pathways have many potential uses from suppression of cancer, proliferative diseases as well as aging

Anandamide analogs as affinity probes for proteins of the endocannabinoid system

Anandamide, the major endogenous cannabimimetic, was used as a molecular template for the design and synthesis of several series of compounds. The objective of this study was to identify the structural determinants for recognition of endocannabinoid substances by each of the four proteins of the endocannabinoid system (CB1 and CB2 receptors, anandamide amidase and anandamide transporter protein). The information derived from this structure-activity relationship study was used to guide the design of pharmacological probes for these proteins. ^ A strategy was identified for the improvement of the metabolic stability of anandamide. First, introduction of methyl groups at the 1′ and 2′ positions of anandamide, led to increased resistance to anandamide amidase. 1′-methylation was proven to be superior in providing hydrolytic stability. The resultant methylated analogs exhibited a significant degree of stereoselectivity in their interactions with both, the CB1 receptor and anandamide amidase. Based on these results, a partial CB1 pharmacophoric model was proposed. ^ The structure-activity relationship that was developed for anandamide amidase allowed the design of a ligand affinity chromatography system for the purification of this enzyme. This chromatography system made possible a 4,500-fold purification of anandamide amidase. The pure enzyme was functional and had similar substrate specificity with that of the crude enzyme preparation. Furthermore, arachidonyl aldehyde and its congeners were identified as potent, tight binding, reversible inhibitors of anandamide amidase.

Structural determinants for recognition and translocation by the anandamide transporter.

The biological actions of anandamide (arachidonylethanolamide), an endogenous cannabinoid lipid, are terminated by a two-step inactivation process consisting of carrier-mediated uptake and intracellular hydrolysis. Anandamide uptake in neurons and astrocytes is mediated by a high-affinity, Na+-independent transporter that is selectively inhibited by N-(4-hydroxyphenyl)-arachidonamide (AM404). In the present study, we examined the structural determinants governing recognition and translocation of substrates by the anandamide transporter constitutively expressed in a human astrocytoma cell line. Competition experiments with a select group of analogs suggest that substrate recognition by the transporter is favored by a polar nonionizable head group of defined stereochemical configuration containing a hydroxyl moiety at its distal end. The secondary carboxamide group interacts favorably with the transporter, but may be replaced with either a tertiary amide or an ester, suggesting that it may serve as hydrogen acceptor. Thus, 2-arachidonylglycerol, a putative endogenous cannabinoid ester, also may serve as a substrate for the transporter. Substrate recognition requires the presence of at least one cis double bond situated at the middle of the fatty acid carbon chain, indicating a preference for ligands whose hydrophobic tail can adopt a bent U-shaped conformation. On the other hand, uptake experiments with radioactively labeled substrates show that no fewer than four cis nonconjugated double bonds are required for optimal translocation across the cell membrane, suggesting that substrates are transported in a folded hairpin conformation. These results outline the general structural requisites for anandamide transport and may assist in the development of selective inhibitors with potential clinical applications

Structural determinants for recognition and translocation by the anandamide transporter

The biological actions of anandamide (arachidonylethanolamide), an endogenous cannabinoid lipid, are terminated by a two-step inactivation process consisting of carrier-mediated uptake and intracellular hydrolysis. Anandamide uptake in neurons and astrocytes is mediated by a high-affinity, Na(+)-independent transporter that is selectively inhibited by N-(4-hydroxyphenyl)-arachidonamide (AM404). In the present study, we examined the structural determinants governing recognition and translocation of substrates by the anandamide transporter constitutively expressed in a human astrocytoma cell line. Competition experiments with a select group of analogs suggest that substrate recognition by the transporter is favored by a polar nonionizable head group of defined stereochemical configuration containing a hydroxyl moiety at its distal end. The secondary carboxamide group interacts favorably with the transporter, but may be replaced with either a tertiary amide or an ester, suggesting that it may serve as hydrogen acceptor. Thus, 2-arachidonylglycerol, a putative endogenous cannabinoid ester, also may serve as a substrate for the transporter. Substrate recognition requires the presence of at least one cis double bond situated at the middle of the fatty acid carbon chain, indicating a preference for ligands whose hydrophobic tail can adopt a bent U-shaped conformation. On the other hand, uptake experiments with radioactively labeled substrates show that no fewer than four cis nonconjugated double bonds are required for optimal translocation across the cell membrane, suggesting that substrates are transported in a folded hairpin conformation. These results outline the general structural requisites for anandamide transport and may assist in the development of selective inhibitors with potential clinical applications

Synthesis and binding study of certain 6-arylalkanamides as molecular probes for cannabinoid receptor subtypes

Tetrahydrocannabinol and other mixed cannabinoid (CB) receptors CB(1)/CB(2) receptor agonists are well established to elicit antinociceptive effects and psychomimetic actions, however, their potential for abuse have dampened enthusiasm for their therapeutic development. In an effort to refine a semi-rigid structural framework for CB(2) receptors binding, we designed novel compounds based on aromatic moiety and flexible linker with various amides mimicking the outlook of the endogenous anandamide which could provide as CB(2) receptor ligand. In this direction, we developed and synthesized new aryl or arylidene hexanoic acid amides and aryl alkanoic acid diamide carrying different head groups. These new compounds were tested for their affinities for human recombinant CB receptors CB(1) and CB(2) and fatty acid amide hydrolase. Although, the preliminary screening of these compounds demonstrated weak binding activity towards CB receptor subtypes at 10 µmole, yet this template still could serve up as probes for further optimization and development of affinity ligand for CB receptors