Evaluation of the Analgesic Effect of High-Cannabidiol-Content Cannabis Extracts in Different Pain Models by Using Polymeric Micelles as Vehicles.

Currently, cannabis is considered an attractive option for the treatment of various diseases, including pain management. Thus, developing new analgesics is paramount for improving the health of people suffering from chronic pain. Safer natural derivatives such as cannabidiol (CBD) have shown excellent potential for the treatment of these diseases. This study aimed to evaluate the analgesic effect of a CBD-rich cannabis extract (CE) encapsulated in polymeric micelles (CBD/PMs) using different pain models. The PEG-PCL polymers were characterized by gel permeation chromatography and 1H-NMR spectroscopy. PMs were prepared by solvent evaporation and characterized by dynamic light scattering (DLS) and transmission electron microscopy. The analgesic activity of CBD/PMs and nonencapsulated CE rich in CBD (CE/CBD) was evaluated using mouse thermal, chemical, and mechanical pain models. The acute toxicity of the encapsulated CE was determined by oral administration in mice at a dose of 20 mg/kg for 14 days. The release of CBD from the nanoparticles was assessed in vitro using a dialysis experiment. CBD/PMs with an average hydrodynamic diameter of 63.8 nm obtained from a biocompatible polyethylene glycol-block-polycaprolactone copolymer were used as nanocarriers for the extract formulations with 9.2% CBD content, which corresponded with a high encapsulation efficiency of 99.9%. The results of the pharmacological assays indicated that orally administered CBD/PMs were safe and exerted a better analgesic effect than CE/CBD. The micelle formulation had a significant analgesic effect in a chemical pain model, reaching a percentage of analgesia of 42%. CE was successfully encapsulated in a nanocarrier, providing better stability. Moreover, it proved to be more efficient as a carrier for CBD release. The analgesic activity of CBD/PMs was higher than that of free CE, implying that encapsulation is an efficient strategy for improving stability and functionality. In conclusion, CBD/PMs could be promising therapeutics for pain management in the future.

Extracts of Renealmia alpinia (Rottb.) MAAS Protect against Lethality and Systemic Hemorrhage Induced by Bothrops asper Venom: Insights from a Model with Extract Administration before Venom Injection.

Renealmia alpinia (Rottb.) MAAS, obtained by micropropagation (in vitro) and wild forms have previously been shown to inhibit some toxic activities of Bothrops asper snake venom if preincubated before injection. In this study, assays were performed in a murine model in which extracts were administered for three days before venom injection. R. alpinia extracts inhibited lethal activity of B. asper venom injected by intraperitoneal route. Median Effective Dose (ED50) values were 36.6 ± 3.2 mg/kg and 31.7 ± 5.4 mg/kg (p > 0.05) for R. alpinia wild and in vitro extracts, respectively. At a dose of 75 mg/kg, both extracts totally inhibited the lethal activity of the venom. Moreover, this dose prolonged survival time of mice receiving a lethal dose of venom by the intravenous route. At 75 mg/kg, both extracts of R. alpinia reduced the extent of venom-induced pulmonary hemorrhage by 48.0% (in vitro extract) and 34.7% (wild extract), in agreement with histological observations of lung tissue. R. alpinia extracts also inhibited hemorrhage in heart and kidneys, as evidenced by a decrease in mg of hemoglobin/g of organ. These results suggest the possibility of using R. alpinia as a prophylactic agent in snakebite, a hypothesis that needs to be further explored.

Inhibition of venom serine proteinase and metalloproteinase activities by Renealmia alpinia (Zingiberaceae) extracts: comparison of wild and in vitro propagated plants.

ETHNOPHARMACOLOGICAL RELEVANCE: The plant Renealmia alpinia has been used in folk medicine to treat snakebites in the northwest region of Colombia. In addition, it has been shown to neutralize edema-forming, hemorrhagic, lethal, and defibrin(ogen)ating activities of Bothrops asper venom. In this work, extracts of Renealmia alpinia obtained by micropropagation (in vitro) and from specimens collected in the wild were tested and compared in their capacity to inhibit enzymatic and toxic activities of a snake venom metalloproteinase isolated from Bothrops atrox (Batx-I) venom and a serine proteinase (Cdc SII) from Crotalus durissus cumanensis venom. MATERIALS AND METHODS: We have investigated the inhibition capacity of Renealmia alpinia extracts on enzymatic and toxic actions of isolated toxins, a metalloproteinase and a serine proteinase. The protocols investigated included inhibition of proteolytic activity on azocasein, inhibition of proteolytic activity on fibrinogen, inhibition of pro-coagulant activity, inhibition of hemorrhagic activity and inhibition of edema-forming activity. RESULTS: Colorimetric assays detected the presence of terpenoids, flavonoids, tannins and coumarins in Renealmia alpinia extracts. Renealmia alpinia extracts inhibited the enzymatic, hemorrhagic and fibrinogenolytic activities of Batx-I. Extracts also inhibited coagulant, defibrin(ogen)ating and edema-forming activities of Cdc SII. Results highlight that Renealmia alpinia in vitro extract displayed comparable inhibitory capacity on venom proteinases that Renealmia alpinia wild extract. No alteration was observed in the electrophoretic pattern of venom proteinases after incubation with Renealmia alpinia extracts, thus excluding proteolytic degradation or protein denaturation/precipitation as a mechanism of inhibition. CONCLUSIONS: Our results showed that Renealmia alpinia wild and in vitro extracts contain compounds that neutralize metallo- and serine proteinases present in snake venoms. The mechanism of inhibition is not related to proteolytic degradation of the enzymes nor protein aggregation, but is likely to depend on molecular interactions of secondary metabolites in the plant with these venom proteinases.