Effects of virgin olive oil phenolics on scavenging of reactive nitrogen species and upon nitrergic neurotransmission.

The major phenolics from the polar fraction of virgin olive oil (caffeic acid, oleuropein, tyrosol and hydroxytyrosol) have well-established antioxidant activities but their effects on reactive nitrogen species and nitrergic neurotransmission have not been fully investigated. The three catechol compounds were active as scavengers of nitric oxide generated spontaneously from the decomposition of sodium nitroprusside (approximately 50% inhibition achieved at 75 microM), and had similar ability to scavenge chemically generated peroxynitrite, as determined by an alpha1-antiproteinase inactivation assay (67.2%-92.4% reduction when added at 1 mM). Tyrosol was less active in these tests, but does not possess the catechol functionality. Despite their ability to interact with chemically prepared nitric oxide, neither oleuropein nor hydroxytyrosol at 5 microM altered NO*-mediated relaxations of the nerve-stimulated rat anococcygeus preparation, but this may be because the nitrergic transmitter is protected from the effects of externally applied scavengers. In conclusion, the phenolics found in virgin olive oil possess ability to scavenge reactive oxygen and nitrogen species that are implicated in human pathologies, but their impact may be restricted to those species present in the extracellular environment.

Anti-inflammatory activity of Agave intermixta Trel. and Cissus sicyoides L., species used in the Caribbean traditional medicine.

Agave intermixta Trel. and Cissus sicyoides L. are two tropical plants originating from the Dominican Republic. Aqueous extracts from these species are used in traditional medicine. In contrast, biological activity and toxicity of these plants are not yet evaluated systematically. The aim of the present work is to investigate a potential anti-inflammatory activity, and to elucidate the toxicity of the extracts. No lethal effects were produced after oral administration of the extracts. The values of the medium lethal doses after intraperitoneal administration were quite high for both species, although A. intermixta seems to be rather more toxic than C. sicyoides. The anti-inflammatory effects have been investigated in two experimental in vivo models. The carrageenan-induced rat paw oedema was chosen as a model for general inflammation, and the mice ear oedema test using tetradecanoylphorbol acetate as inflammatory agent as a model of topical inflammation. Dry extracts from decoctions of A. intermixta leaves and C. sicyoides stems were administered in doses of 300 and 500 mg/kg (p.o.) in the general model, and in doses of 3 and 5 mg/mouse ear for both plants in the topical model. In the general anti-inflammation assay, the oral administration of both extracts produced a significant anti-inflammatory effect, most pronounced for A. intermixta than for C. sicyoides. In the topical model, the administration of both extracts produced similar inhibitions of the oedema, with a reduction of approximately 50% in comparison with the control group. In homogenated tissue samples from the inflamed areas, a distinct decrease in the level of myeloperoxidase enzyme was noted.