Isopulegol

Pharm Res. 2014 Aug;31(8):1907-18.

Saturated long-chain esters of isopulegol as novel permeation enhancers for transdermal drug delivery.[Pubmed: 24449443]

Saturated long-chain esters of Isopulegol were synthesized and their activities as permeation enhancers for transdermal delivery of amlodipine and flurbiprofen were investigated, in contrast to the saturated fatty acids and Isopulegol, as well as their physical mixtures.
METHODS AND RESULTS:
In vitro permeation experiments, confocal laser scanning microscopy (CLSM) and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy were introduced to investigate the regulation of enhancers in the skin permeability and biophysical properties. With in vitro cytotoxicity test and in vivo erythema model, the skin irritation of enhancers was evaluated. The esters significantly increased the permeation of amlodipine and flurbiprofen, whereas saturated fatty acids and Isopulegol had no such effect and even decreased the drug permeation when they were used alone or in combination. These results were supported by CLSM and ATR-FTIR studies, which revealed that only the esters could decrease the order of the alkyl chains in the skin lipids. Additionally, almost no skin irritation and cytotoxicity were observed for these esters.
CONCLUSIONS:
Saturated long-chain esters of Isopulegol are shown to be suitable permeation enhancers for transdermal drug delivery. Covalent attachment of Isopulegol and saturated fatty acids might represent a promising strategy to design novel and potent permeation enhancers.

Fitoterapia. 2009 Dec;80(8):506-13.

Effects of isopulegol on pentylenetetrazol-induced convulsions in mice: possible involvement of GABAergic system and antioxidant activity.[Pubmed: 19559770 ]

The present study investigated the effects of Isopulegol, a monoterpene alcohol, in PTZ-induced convulsions and verified possible involved mechanisms.
METHODS AND RESULTS:
Saline, Isopulegol or diazepam were intraperitonealy injected 30 min before PTZ. The latency for development of convulsions and mortality, as well as the mortality protection percentage was recorded. For investigating the involvement of GABAergic system, flumazenil was utilized. The activity of antioxidant enzyme catalase as well as the levels of reduced glutathione and lipid peroxidation were measured in brain hippocampus. Similarly to diazepam, Isopulegol significantly prolonged the latency for convulsions and mortality of mice. All animals were protected against mortality at higher dose of Isopulegol. Flumazenil pretreatment decreased the prolongation of seizure latency induced by both diazepam and Isopulegol, although it was not able to reverse the latency and protection percent for mortality. Isopulegol also significantly prevented PTZ-induced increase in lipid peroxidation, preserved catalase activity in normal levels, and prevented the PTZ-induced loss of GSH in hippocampus of mice.
CONCLUSIONS:
These results suggest that the anticonvulsant and bioprotective effects of Isopulegol against PTZ-induced convulsions are possibly related to positive modulation of benzodiazepine-sensitive GABA(A) receptors and to antioxidant properties.

Naunyn Schmiedebergs Arch Pharmacol. 2009 Sep;380(3):233-45.

Gastroprotective activity of isopulegol on experimentally induced gastric lesions in mice: investigation of possible mechanisms of action.[Pubmed: 19479241]

The present study investigated whether Isopulegol, a monoterpene present in essential oils of several aromatic plants, would be able to promote some gastroprotective effect and also verified the possible mechanisms involved in this action.
METHODS AND RESULTS:
For this study, ethanol- and indomethacin-induced gastric ulcer models in mice and histopathological assessment were used. The roles of NO, sulfhydryls (glutathione, GSH), ATP-sensitive K(+) channels (K(ATP) channels), and prostaglandins were also investigated. Isopulegol exhibited a dose-related gastroprotective effect against ethanol-induced lesions, while the pretreatment with glibenclamide and indomethacin [but not with N(G)-nitro-L-arginine methyl ester] were able to reverse this action. The pretreatment with Isopulegol also restored GSH levels to normal levels and exhibited dose-related gastroprotective effect against indomethacin-induced ulcer.
CONCLUSIONS:
The results suggested that Isopulegol presents significant gastroprotective effects in both ethanol- and indomethacin-induced ulcer models, which appear to be mediated, at least in part, by endogenous prostaglandins, K(ATP) channel opening, and antioxidant properties.

Pharmacol Biochem Behav. 2007 Dec;88(2):141-7.

Central nervous system activity of acute administration of isopulegol in mice.[Pubmed: 17716715]

Isopulegol is a monoterpene alcohol intermediate in the preparation of (-)-menthol and it is present in the essential oils of various plants.
METHODS AND RESULTS:
This work presents behavioral effects of Isopulegol in animal models of open field, elevated plus maze (EPM), rota rod, hole board, barbiturate-induced sleeping time, tail suspension and forced swimming tests in mice. Isopulegol was administered intraperitoneally to male mice at single doses of 25 and 50 mg/kg, while diazepam 1 or 2 mg/kg and imipramine 10 or 30 mg/kg were used as standard drugs. The results showed that, similar to diazepam (1 mg/kg), both doses of Isopulegol significantly modified all the observed parameters in the EPM test, without alter the general motor activity in the open field test. In the same way, both doses of Isopulegol increased the number of head dips in the hole-board test. Forced swimming and tail suspension tests showed that Isopulegol (25 and 50 mg/kg) was able to induce a significant increase in the immobility time, in opposite to imipramine, a recognized antidepressant drug. There was a decrease in the sleep latency time and prolongation of the pentobarbital-induced sleeping time with both doses of Isopulegol. Different from diazepam (2 mg/kg), Isopulegol (25 e 50 mg/kg) had no effect on the motor coordination of animals in the rota rod test.
CONCLUSIONS:
These results showed that Isopulegol presented depressant- and anxiolytic-like effects.