Adsorption of natural annatto dye by kaolin: kinetic and equilibrium.

The adsorption of annatto dye was analysed using kaolin clay as the adsorbent. In this work, the influence of the adsorbent particle size, agitation (0 and 100 rpm), temperature (25, 40, and 60°C), and salt presence (sodium chloride and sodium sulphate at 1, 2 and 3 wt%) on the adsorption process was studied. The adsorption increased 14.21% for particles smaller than 45 µm and the agitation (100 rpm) led to an increase of 22.41% compared to the system without agitation. The ΔG° (237.711 kJmol-1) indicated that the adsorption process was spontaneous. The negative value of ΔS° (-408.999 Jmol-1K-1) and ΔH° (-115.829 kJmol-1) showed an exothermic physisorption process. The adsorption kinetics follows the pseudo-second-order model. In the adsorption equilibrium, the tested models provided good correlation coefficients ranging from 0.744 to 0.999 with the best fit observed for the Langmuir model. The maximum adsorption capacity of the kaolin clay for the annatto dye was obtained at 25°C with 1% of sodium sulphate (q max = 59.88 mgg-1).

Antidepressant-like effect of the extract from leaves of Schinus molle L. in mice: evidence for the involvement of the monoaminergic system.

Schinus molle L. (Anacardiaceae), among other uses, is popularly employed for the treatment of depression. In this study, the antidepressant-like effect of the hexanic extract from leaves of S. molle was investigated in the mouse tail suspension test (TST), a predictive model of depression. The immobility time in the TST was significantly reduced by the extract (dose range 30-600 mg/kg, p.o.), without accompanying changes in ambulation when assessed in an open-field test. The efficacy of extract was found to be comparable to that of fluoxetine (10 mg/kg, p.o.). The anti-immobility effect of the extract (100 mg/kg, p.o.) was prevented by pretreatment of mice with p-chlorophenylalanine methyl ester (PCPA, 100 mg/kg, i.p., an inhibitor of serotonin synthesis, for four consecutive days), NAN-190 (0.5 mg/kg, i.p., a 5-HT(1A) receptor antagonist), WAY100635 (0.1 mg/kg, s.c., a selective 5-HT(1A) receptor antagonist), ketanserin (5 mg/kg, i.p., a 5-HT(2A/2C) receptor antagonist), MDL72222 (0.1 mg/kg, i.p., a 5-HT(3) receptor antagonist), prazosin (1 mg/kg, i.p., an alpha(1)-adrenoceptor antagonist), yohimbine (1 mg/kg, i.p., an alpha(2)-adrenoceptor antagonist), SCH23390 (0.05 mg/kg, s.c., a D(1) receptor antagonist) or sulpiride (50 mg/kg, i.p., a D(2) receptor antagonist). It may be concluded that the hexanic extract of S. molle produces an antidepressant-like effect that seems to be dependent on its interaction with the serotonergic, noradrenergic and dopaminergic systems. These results provide evidence that the extract from S. molle shares with established antidepressants some pharmacological effects, at least at a preclinical level.