Pharmacological and molecular docking assessment of cryptotanshinone as natural-derived analgesic compound.

Medicinal plants from traditional chinese medicine are used increasingly worldwide for their benefits to health and quality of life for the relevant clinical symptoms related to pain. Among them, Salvia miltiorrhiza Bunge is traditionally used in asian countries as antioxidant, anticancer, anti-inflammatory and analgesic agent. In this context, several evidences support the hypothesis that some tanshinones, in particular cryptotanshinone (CRY), extracted from the roots (Danshen) of this plant exhibit analgesic actions. However, it is surprisingly noted that no pharmacological studies have been carried out to explore the possible analgesic action of this compound in terms of modulation of peripheral and/or central pain. Therefore, in the present study, by using peripheral and central pain models of nociception, such as tail flick and hot plate test, the analgesic effect of CRY in mice was evaluated. Successively, by the aim of a computational approach, we have evaluated the interaction mode of this diterpenoid on opioid and cannabinoid system. Finally, CRY was dosed in mice serum by an HPLC method validated according to European Medicines Agency guidelines validation rules. Here, we report that CRY displayed anti-nociceptive activity on both hot plate and tail flick test, with a prominent long-lasting peripheral analgesic effect. These evidences were indirectly confirmed after the daily administration of the tanshinone for 7 and 14 days. In addition, the analgesic effect of CRY was reverted by naloxone and cannabinoid antagonists and amplified by arginine administration. These findings were finally supported by HPLC and docking studies, that revealed a noteworthy presence of CRY on mice serum 1 h after its intraperitoneal administration and a possible interaction of tested compound on µ and k receptors. Taken together, these results provide a new line of evidences showing that CRY can produce analgesia against various phenotypes of nociception with a mechanism that seems to be related to an agonistic activity on opioid system.

Synergistic antinociceptive interaction between palmitoylethanolamide and tramadol in the mouse formalin test.

Pharmacological synergism has been used to obtain a higher efficacy using drug concentrations at which side effects are minimal. In this study, the pharmacological antinociceptive interaction between N-palmitoylethanolamide (PEA) and tramadol was investigated. The individual concentration-response curves for PEA (0.1-56.2 µg/paw) and tramadol (1-56.2 µg/paw) were evaluated in mice in which nociception was induced by an intraplantar injection of 2% formalin. Isobolographic analysis was used to evaluate the pharmacological interaction between PEA (EC50=23.7±1.6 µg/paw) and tramadol (EC50=26.02±2.96 µg/paw) using the EC50 and a fixed 1:1 ratio combination. The isobologram demonstrated that the combinations investigated in this study produced a synergistic interaction; the experimental values (Zexp=9.5±0.2 µg/paw) were significantly smaller than those calculated theoretically (Zadd=24.8±0.2 µg/paw). The antinociceptive mechanisms of the PEA and tramadol combination involved the opioid receptor, transient receptor potential cation channel subfamily V member 1 (TRPV1), and peroxisome proliferator-activated receptor alpha (PPAR-α). The sedative effect of the combination of PEA and tramadol was less than that generated by individual treatments. These findings suggest that the PEA and tramadol combination produced enhanced antinociceptive efficacy at concentrations at which side effects are minimal.

Experimental dog model for assessment of fasting and postprandial fatty acid metabolism: pitfalls and feasibility.

The dog is a widely-used model for conducting metabolic studies. This is mainly due to its large size and its physiology which is relatively similar to that of humans. Here, we attempted to optimize a postprandial metabolic study protocol used in dogs. Following acclimatization, female mongrel dogs underwent 9 h profiling for time-course baseline plasma data on triglyceride, adrenocorticotropic hormone (ACTH) and cortisol levels. One week later, carotid and jugular catheters were surgically inserted for sampling and infusions. Initial post-operative care, based on the literature (Protocol 1), consisted of analgesia (buprenorphine every 8-12 h and 2-3 doses/day of acepromazine), restriction by Pavlov harness within cages, and a two- to three-day recovery period. Throughout the experiment, dogs received a lipid tracer diluted in 5% bovine serum albumin (BSA). Compared with baseline, animals vomited (n = 6/6) and exhibited high ACTH + cortisol levels (stress biomarkers), resulting in blunted triglyceride peak levels. To avoid these undesirable effects, post-operative care was modified (Protocol 2) as follows: animals (n = 19) were given a single dose of buprenorphine and no acepromazine, were unrestrained and free to move within cages, the recovery period was extended to seven days, and the lipid tracer was diluted in 0.002% versus 5% BSA. Using this modified protocol, postprandial plasma-triglyceride and ACTH/cortisol patterns were similar to baseline values. Controlling for stressors, as well as for factors which may alter proper digestion, is critical for all postprandial metabolic studies. Our results show that an optimized postprandial metabolic protocol used in dogs reduces experimental variability, while improving animal care and comfort.

GW-1000. GW Pharmaceuticals.

GW Pharmaceuticals is developing GW-1000 (Sativex), a narrow ratio delta9-tetrahydrocannabinol:cannabidiol product for the potential treatment of multiple sclerosis, spinal cord injury, neurogenic pain and peripheral neuropathy. In March 2003, the company filed for approval for the treatment of MS with the UK Medicines Control Agency, and in May 2004, filed for new drug submission with Health Canada.

Assessment of substitution in the second pharmacophore of Dmt-Tic analogues.

The Dmt-Tic pharmacophore exhibits potent delta-opioid receptor antagonism. Analogues with substitutions in the second pharmacophore with (1, 1') or without a COOH function (2-9) were synthesized: several had high delta affinity (1', 2, 7, and 9), but exhibited low to non-selectivity toward mu receptors similar to H-Dmt-Tic-amide and H-Dmt-Tic-ol. Functional bioactivity indicated high delta antagonism (pA2 7.4-7.9) (1', 2, and 9) and modest mu agonism, pEC50 (6.1-6.3) (1', 2, 8, and 9), but with Emax values analogous to dermorphin. These Dmt-Tic analogues with mixed delta antagonist/mu agonist properties would appear to be better candidates as analgesics than pure mu agonists.