Affinin and hexahydroaffinin: Chemistry and toxicological profile.

The present work aimed to determine the safety parameters of two new alkamides, affinin and hexahydroaffinin, with antinociceptive activity. To predict the preliminary acute toxicity, we used the acute and subchronic toxicity (50 mg/kg, orally [po]) in Swiss Webster mice. Genotoxicity assayed via analysis of cell micronuclei of the femoral bone marrow in mice; at the same time, metabolic parameters determined from peripheral blood samples. Furthermore, to discard the neuropharmacological effects, we assessed the ambulatory activity in mice to determine the possible effects in the central nervous system. Finally, we used capsaicin as a positive control of alkamides. According to our results, hexahydroaffinin (LD50 ≥ 5,000 mg/kg, po) is significantly less noxious than affinin (LD50 = 1,442.2 mg/kg, po) or capsaicin (LD50 = 489.9 mg/kg, po). In subchronic administration, we did not observe any changes in hematological or biochemical parameters in any compound analyzed from peripheral blood samples. Finally, the data from the genotoxicity assay showed micronuclei formation in 28%, 5%, and 3% of mice in the capsaicin, affinin, and hexahydroaffinin groups, respectively. With the results obtained in the present investigation, we suggest that affinin and hexahydroaffinin are not only useful candidates for possible new drugs but also safe compounds.

Antinociceptive effect of natural and synthetic alkamides involves TRPV1 receptors.

OBJECTIVE: To establish the role of TRPV1 receptor in the antinociceptive effect of natural alkamides (i.e. affinin, longipinamide A, longipenamide A and longipenamide B) isolated from Heliopsis longipes (A. Gray) S.F. Blake and some related synthetic alkamides (i.e. N-isobutyl-feruloylamide and N-isobutyl-dihydroferuloylamide). METHODS: The orofacial formalin test was used to assess the antinociceptive activity of natural (1-30 µg, orofacial region) and synthetic alkamides (0.1-100 µg, orofacial region). The alkamide capsaicin was used as positive control, while capsazepine was used to evaluate the possible participation of TRPV1 receptor in alkamide-induced antinociception. KEY FINDINGS: Natural (1-30 µg) and synthetic (0.1-100 µg) alkamides administered to the orofacial region produced antinociception in mice. The antinociceptive effect induced by affinin, N-isobutyl-feruloylamide and N-isobutyl-dihydroferuloylamide was antagonized by capsazepine but not by vehicle. CONCLUSIONS: These results suggest that alkamide affinin, longipinamide A, longipenamide A and longipenamide B isolated from Heliopsis longipes as well as the synthesized analogue compounds N-isobutyl-feruloylamide and N-isobutyl-dihydroferuloylamide produce their effects by activating TRPV1 receptor and they may have potential for the development of new analgesic drugs for the treatment of orofacial pain.

Synthesis of oleanolic acid derivatives: In vitro, in vivo and in silico studies for PTP-1B inhibition.

Non-insulin dependent diabetes mellitus is a multifactorial disease that links different metabolic routes; a point of convergence is the enzyme PTP-1B which turns off insulin and leptin receptors involved in glucose and lipid metabolism, respectively. Pentacyclic acid triterpenes such as oleanolic acid (OA) have proved to be excellent PTP-1B inhibitors, thus, the purpose of current work was to generate a series of derivatives that improve the pharmacological effect of OA. Our findings suggest that the presence of the carboxylic acid and/or its corresponding reduction product carbinol derivative (H-bond donor) in C-28 is required to maintain the inhibitory activity; moreover, this is further enhanced by ester or ether formation on C-3. The most active derivatives were cinnamoyl ester (6) and ethyl ether (10). Compound 6 showed potent in vitro inhibitory activity and significantly decrease of blood glucose levels on in vivo experiments. Meanwhile, 10 showed contrasting outcomes, since it was the compound with higher inhibitory activity and selectivity over PTP-1B and has improved interaction with site B, according with docking studies, the in vivo antidiabetic effect was similar to oleanolic acid. In conclusion, oleanolic acid derivatives have revealed an enhanced inhibitory effect over PTP-1B activity by increasing molecular interactions with either catalytic or allosteric sites and producing a hypoglycaemic effect on non insulin dependent diabetes mellitus rat model.