The results corroborate the use of Cymbopogon citratus in folk medicine and suggest that the anxiolytic-like effect of its EO is mediated by the GABA(A) receptor-benzodiazepine complex.

Ocimum gratissimum is used in popular medicine to treat painful diseases. The antinociceptive properties of O. gratissimum essential oil (OgEO) and two of its active principles (eugenol and myrcene) were tested in classic models of pain (hot plate test and formalin test). Adult male C57BL/6 J mice acutely received corn oil (control group, p.o.), morphine (positive control group, 5 mg/kg, i.p.), OgEO (10, 20, or 40 mg/kg, p.o.), eugenol or myrcene (both at 1, 5, or 10 mg/kg, p.o.). The highest doses of all tested drugs significantly increased the latency to lick the paw(s) in the hot plate test compared with the control group. OgEO at a dose of 40 mg/kg and eugenol and myrcene at a dose of 10 mg/kg were effective in minimizing animal pain in the first and second phases of the formalin test. The antinociceptive effect shown by all drugs tested in hot plate test was reverted by naloxone administration (1 mg/kg), indicating opiod system participation. These results demonstrate the beneficial effects of OgEO and its active principles against neurogenic and inflammatory pain. Our findings demonstrate that OgEO and its isolated active principles exhibited antinociceptive activity in murine pain models.

Multiple sclerosis is an inflammatory disease of the central nervous system. Chronic pain is one of the main symptoms, affecting many patients. Studies show that the lignans or the apolar extracts of Phyllanthus amarus have antinociceptive effects in different animal models. To evaluate the antihypernociceptive effect of a hexanic extract of P. amarus in experimental autoimmune encephalomyelitis in mice, the chemical composition of the hexanic extract was analyzed by gas chromatography mass spectrometry. After EAE induction, animals were treated with the hexanic extract of P. amarus for 26 consecutive days. Motor coordination and mechanical hypernociception were evaluated on alternate days. The principal lignans found were phyllanthin, niranthin, and 5-demethoxyniranthin. The hexanic extract of P. amarus at a dose of 100, 200, or 400 mg/kg did not affect the development of the disease. The motor coordination and pain threshold of the treated animals were not altered in this experiment. In conclusion, in this test, the hexanic extract of P. amarus did not show evidence of antihypernociceptive activity in experimental autoimmune encephalomyelitis.

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Epidemiological studies have shown an inverse association between coffee consumption and the development of Parkinson’s disease (PD). The present investigation aimed to evaluate the effects of caffeine and green (non-roasted) coffee extract in experimental models of PD. The effects of the oral treatment with green coffee extracts (CE, Coffea arabica 100 or 400 mg/kg) and caffeine (31.2 mg/kg) were evaluated on catalepsy induced by haloperidol in mice, and unilateral 6-OHDA lesion of medial forebrain bundle (MFB) or striatum in rats. Also, the in vitro antioxidant activity and the monoamine levels in the striatum were investigated. CE presented a mild antioxidant activity in vitro and its administration decreased the catalepsy index. CE at the dose of 400 mg/kg induced ipsilateral rotations 14 days after the lesion; however, chronic 30-day CE and caffeine treatments did not interfere with the animals’ rotation after apomorphine or methamphetamine challenges in animals with MFB lesion, nor on monoamines levels. Furthermore, CE and caffeine were effective in inhibiting the asymmetry between ipsilateral and contralateral rotations induced by methamphetamine and apomorphine in animals with lesion in the striatum but did not avoid the monoamines depletion. These results suggest a pro-dopaminergic action of CE, although its mechanism remains unclear.