Biological effects of Ocimum gratissimum L. are due to synergic action among multiple compounds present in essential oil.

Species of genus Ocimum (Lamiaceae) are economically important due to their essential oils and utilization as medicine for many disorders, including the central nervous system. A previous study showed seasonal variations in chemical profile and in central nervous system activities of essential oil from Ocimum gratissimum L. The preparation obtained in spring was able to protect the animals against tonic episodes induced by electroshock while those obtained in other seasons were effective in increasing barbiturate-induced sleeping time. The chemical analysis of essential oils showed eugenol and 1,8-cineole as principal compounds and trans-caryophyllene as a sesquiterpene in higher proportion. In the present study these three compounds were evaluated, separately or mixed in the same proportion detected in spring, in the open-field and rota-rod tests, against convulsions induced by pentylenetetrazole (PTZ; 60 mg/kg, subcutaneously, s.c.) or maximal electroshock (MES; 50 mA, 0.11 s) and in sodium pentobarbital (45 mg/kg, intraperitoneally, i.p.)-induced sleeping time. The compounds, isolated or in association, did not show efficaciousness in altering convulsive episodes, and only when in association were able to increase sleeping time duration. The absence of similar essential oil activity in the isolated compounds contributes to the idea that the major compounds are not always responsible for a biological effect observed in medicinal plant preparations. This view reinforces the concept of a multitargeted approach as a therapeutic strategy, contributing to an integrated understanding of the phenomena related to experimental activity of a complex herbal mixture.

Effects of the essential oil from Citrus aurantium L. in experimental anxiety models in mice.

Citrus aurantium L. is popularly used to treat anxiety, among other indications suggesting central nervous system action. Previous studies showed anxiolytic effect in the essential oil from peel in mice evaluated on the elevated plus maze [Carvalho-Freitas, M.I.R., Costa, M., 2002. Anxiolytic and sedative effects of extracts and essential oil from Citrus aurantium L. Biological and Pharmaceutical Bulletin 25, 1629-1633.]. In order to better characterize the activity of the essential oil, it was evaluated in two other experimental models: the light-dark box and the marble-burying test, respectively related to generalized anxiety disorder and to obsessive compulsive disorder. Mice were treated acutely by oral route 30 min (single dose) or once a day for 15 days (repeated doses) before experimental procedures. In light-dark box test, single treatment with essential oil augmented the time spent by mice in the light chamber and the number of transitions between the two compartments. There were no observed alterations in the parameters evaluated in light-dark box after repeated treatment. Otherwise, single and repeated treatments with essential oil were able to suppress marble-burying behavior. At effective doses in the behavioral tests, mice showed no impairment on rotarod procedure after both single and repeated treatments with essential oil, denoting absence of motor deficit. Results observed in marble-burying test, related to obsessive compulsive disorder, appear more consistent than those observed in light-dark box.