Croton argenteus preparation inhibits initial growth, mitochondrial respiration and increase the oxidative stress from Senna occidentalis seedlings.

Senna ocidentalis is a weed, native to Brazil, considered to infest crops and plantations, and is responsible for yield losses of several crops, particularly soybean. The aim of this work was to evaluate if the Croton argenteus extract and fractions possess phytotoxic activity on S. ocidentalis. The crude ethanolic extract (CEE) and its hexanic (HF), chloroformic (CLF) and ethyl acetate (EAF) fractions were tested in germination, growth, oxidative stress increase, Adenosine triphosphate, L-malate and succinate synthesis. The crude extract and its fractions slowed down the germination of S. ocidentalis and decreased the final percentage of germination. Oxidative stress was also increased in the seedlings, by an increase of catalase, peroxidase, superoxide dismutase, glutathione reductase and lipid peroxidation; and it became clear that the ethyl acetate fraction was more phytotoxic. The results indicate that the crude extract and fractions of C. argenteus compromise the mitochondrial energy metabolism, by the inhibition of mitochondrial ATP production, with a decrease in the production of L-malate and succinate. The ethyl acetate fraction of C. argenteus showed high activity on germination and growth, and these effects take place by means of mitochondrial metabolism alterations and increase the oxidative stress, leading the seedling death.

Role of glutamate and dopamine receptors in the psychopharmacological profile of the indole alkaloid psychollatine.

Psychollatine (1), a new glycoside indole monoterpene alkaloid isolated from Psychotria umbellata, has shown an interesting psychopharmacological profile. This study aimed to investigate the role of NMDA glutamate and dopamine receptors in mediating the properties of 1. Psychollatine (1) was assessed for NMDA-induced seizures, MK-801-induced hyperlocomotion, amphetamine-induced lethality, and apomorphine-induced climbing behavior in mice. Psychollatine (1) (100 mg/kg) and MK-801 (0.3 mg/kg) prevented NMDA-induced seizures (P < 0.01), while 1 (100 mg/kg) attenuated the MK-801-induced hyperlocomotion (P < 0.05). Compound 1 (3 and 10 mg/kg), as well as chlorpromazine (4 mg/kg), prevented amphetamine-induced lethality (P < 0.05). Finally, 1 (10 mg/kg) (P < 0.05), MK-801 (0.2 mg/kg) (P < 0.01), and chlorpromazine (4 mg/kg) (P < 0.01) attenuated apomorphine-induced climbing behavior. The present results strongly support the involvement of NMDA glutamate receptors in the mode of action of psychollatine (1).

Psychopharmacological profile of the alkaloid psychollatine as a 5HT2A/C serotonin modulator.

Behavioral effects of psychollatine, a new glycoside indole monoterpene alkaloid isolated from Psychotria umbellata, was investigated in models of anxiety, depression, memory, tremor, and sedation related to 5-HT and/or GABA neurotransmission. The GABA antagonist picrotoxin and the 5-HT2 antagonist ritanserin were used to examine the role of GABA and 5-HT2 receptors in psychollatine-induced effects. In the light/dark and hole-board models of anxiety, diazepam (0.75 mg/kg) and psychollatine (7.5 and 15 mg/kg) showed anxiolytic-like effect at doses that do not increase sleeping time nor alter spontaneous locomotor activity. The anxiolytic effect of psychollatine was prevented by prior administration of ritanserin, but not of picrotoxin, indicating that 5-HT2 but not GABA receptors are implicated. In the forced swimming model of depression, psychollatine (3 and 7.5 mg/kg) effects were comparable to the antidepressants imipramine (15 mg/kg) and fluoxetine (20 mg/kg). Psychollatine suppressed oxotremorine-induced tremors in all doses. In the step-down learning paradigm, diazepam (0.85 mg/kg), MK-801 (0.15 mg/kg), and psychollatine 100 mg/kg impaired the acquisition of learning and memory consolidation, without interfering with retrieval. It is concluded that the effects of psychollatine at the central nervous system involve serotonergic 5HT2(A/C) receptors.

The alkaloid brachycerine is induced by ultraviolet radiation and is a singlet oxygen quencher.

The effects of ultraviolet (UV) radiation on chlorophyll content and accumulation of the anti-inflammatory monoterpene-indole alkaloid brachycerine in plants and calli of Psychotria brachyceras (Rubiaceae) were investigated. In this study, we also investigated a protective role for brachycerine against stress conditions. Calli and tip cuttings incubated in nutrient media were daily supplemented with 4 or 16 h of UV. High-performance liquid chromatography analyses of methanolic extracts showed only traces of brachycerine in irradiated aseptic cultures, with no alkaloid being observed in control calli. In cuttings, a 10-fold increase in brachycerine content was seen after exposure for 16 h to UV-C, whereas a 4 h daily supplementation doubled the amount of the alkaloid in leaves. Exposure to a UV-B source also doubled the alkaloid yield. In vitro brachycerine was able to quench singlet oxygen. The data indicate a potential protective role for brachycerine against UV radiation, acting as a UV filter (absorption peaks are within the UV range) and a reactive oxygen species scavenger. In addition, UV radiation may be used to increase yields of this compound of pharmaceutical interest.