Partially purified leaf extracts ofMelia azedarach L. inhibit tacaribe virus growth in neonatal mice

Purification and Partial Characterization of an Antiviral Active Peptide from Melia Azedarach L

A peptide associated with antiviral activity, isolated from the high plant Melia azedarach L. was purified and partially characterized. Crude extracts of green leaf were purified by gel filtration on Sephadex G-100 followed by DEAE-Sephadex A-25. After column chromatography purification, an active compound II was revealed by elution with chloroform: methanol (95:5). Further analysis using thin-layer chromatography (TLC) revealed three components. With Rf 0.37 (component II), one of these had the highest antiviral activity as determined by inhibition of VSV replication. Compound II (meliacine) also inhibited the in vitro replication of PrV, HSV-1, HSV-2, Junin virus, Tacaribe virus, and Sindbis virus. Chemical analysis showed the antiviral compound to be a cyclic peptide with aMW 2200–2300 containing only aliphatic aminoacids. An unusual feature of the peptide was the presence of a single glucose unit that could be released by mild alkaline treatment which caused degradation of the peptide.

CpG oligodeoxynucleotides protect newborn mice from a lethal challenge with the neurotropic Tacaribe arenavirus

The innate immune system is key to limiting the early spread of most pathogens and directing the development of Ag-specific immunity. Recently, a number of synthetic molecules that activate the innate immune system by stimulating TLRs have been identified. Among them, synthetic oligodeoxynucleotides (ODNs) containing unmethylated CpG motifs (CpG ODNs) were shown to activate TLR9-bearing B cells, macrophages, and dendritic cells to induce a strong proinflammatory milieu and a type 1-biased immune response that protects mice from a variety of parasitic, bacterial, and viral infections. Although the protective effect of CpG ODN in adult mice was well established, its effectiveness in neonates, which have lower numbers of dendritic, B, and T cells and tend to favor Th2 responses, was unclear. This study uses the New World arenavirus Tacaribe, a neurotropic pathogen that is lethal in newborn mice, to explore the effectiveness of TLR-mediated innate immune responses. Neonatal BALB/c mice treated with CpG ODN at the time of infection had reduced viral load (p < 0.01) and increased survival (52%, p < 0.001 i.p.; 36%, p < 0.05 intranasally). Protection was achieved in mice treated no later than 3 days postchallenge and appears to be mediated by an increase in Ag-specific Abs (IgG and IgM) and to require inducible NO synthase expression and NO production. To our knowledge, this is the first study assessing the mechanisms by which CpG ODN can protect mice from a neurotropic viral infection.

In vitro anthelmintic activity ofMelia azedarach naturalized in Argentina

The anthelmintic activity of the drupe extracts of Melia azedarach L. (Meliaceae) growing in Argentina was tested against tapeworms, hookworms, nodular worms and earthworms, and was shown to be better than the standards piperazine phosphate and hexylresorcinol against tapeworms and hookworms, respectively.

Antiviral activity of an acidic polysaccharides fraction extracted from Cedrela tubiflora leaves

An acidic polysaccharides fraction (APS) obtained from Cedrela tubiflora leaves was tested for antiviral activity. This fraction inhibited the replication of HSV-2 and VSV, while the replication of poliovirus was not affected. APS was not virucidal, but no cytotoxicity was present in the different concentrations of APS assayed.

Anti-inflammatory activities of Trichilia glabra aqueous leaf extract

Trichilia glabra L. aqueous leaf extract exerted a significant antiinflammatory effect 'in vivo' in the zymosan-induced inflammation model. The extract impaired the 'in vitro' activities of polymorphonuclear leukocytes and complement, components of mouse immune system closely related to the inflammatory response induced by zymosan. In particular, a significant reduction in the phagocytic capability and respiratory burst response of mouse polymorphonuclear leukocytes together with an inhibition in the hemolytic activity of mouse complement was observed.

In vivo and in vitro immunomodulatory activities of Trichilia glabra aqueous leaf extracts

The effects of Trichilia glabra (Meliaceae) aqueous leaf extract on mouse lymphocytes were studied. The in vitro proliferation of T and B lymphocytes was completely impaired. Besides, the extract significantly diminished both antibody and delayed hypersensitivity responses in treated mice. These results suggest that the extract exerts a marked immunomodulatory effect on the murine immune system.

Trichilia glabra: effect on the phagocytic activity and respiratory burst response of peritoneal macrophages

A diminution in the phagocytic capability and respiratory burst response of murine peritoneal macrophages was observed when these cells were treated 'in vitro' with Trichilia glabra leaf aqueous extract. The effect was not observed when non-specific phagocytosis was tested. The extract also inhibited binding of opsonized erythrocytes to macrophages, thus indicating that the observed antiphagocytic effect is possibly due to the failure of opsonized particles to bind to these cells. A low molecular weight fraction is responsible for the reported activities.

Neutral polysaccharide from Cedrela tubiflora with anticomplementary activity

A water-soluble polysaccharide extracted from leaves of the Meliaceae Cedrela tubiflora was separated into neutral and acidic polysaccharide fractions. The best anticomplementary activity was exhibited by the neutral product which was further purified by means of gelpermeation chromatography. The composition and methylation analysis of the purified product were determined.

In vitro anti-Junin virus activity of a peptide isolated from Melia azedarach L. leaves

Meliacine, a peptide isolated from leaves of Melia azedarach L. inhibited the multiplication of Junin virus in Vero cells treated with the compound before infection (pre-treatment) or immediately after virus adsorption. Analysis of early events following infection demonstrated that meliacine blocks virus penetration by preventing the uncoating step. The addition of meliacine at different times after infection indicated that meliacine also interferes with the release of infectious particles to the extracellular medium and inhibits the low-pH-induced fusion of infected cells. Intracellular transport of viral glycoproteins to the cell membrane was not affected by meliacine, as revealed by immunofluorescence staining. Taken together, these results suggest that meliacine affects two events of the virus replicative cycle that require membrane fusion: uncoating and budding.

Immunomodulatory activities of Cedrela lilloi and Trichilia elegans aqueous leaf extracts

The effects of Cedrela lilloi and Trichilia elegans (Meliaceae) aqueous leaf extracts on several parameters of the mouse immune system were studied. Both extracts showed a strong anticomplementary activity and inhibited the phagocytosis of opsonized sheep erythrocytes and the activation of the oxidative metabolism by opsonized zymosan on peritoneal macrophages. The in vitro proliferation of spleen T-lymphocytes was also impaired. Furthermore, treatment of mice with the extracts diminished the delayed-type hypersensitivity response to sheep erythrocytes. These results suggest that both extracts exert a marked immunomodulatory effect on the mouse immune system.

Immunomodulatory activities of Cedrela tubiflora leaf aqueous extracts

Human peripheral blood monocytes and polymorphonuclear leukocytes treated with leaf aqueous extracts of the Meliaceae tree Cedrela tubiflora showed a diminution in both their phagocytic and respiratory burst activities. Besides, the extract inhibited the proliferation of Concanavalin A stimulated lymphocytes. A decrease in the hemolytic capacity of the human complement was also observed. The significance of the inhibitory effect observed over some components of the human immune system closely related with the inflammatory process is discussed.

In vitro antiphagocytic effect of Melia azedarach leaf extracts on mouse peritoneal exudate cells

The effect of Melia azedarach L. (Meliaceae) leaf extract on the phagocytic capability and respiratory burst of mouse peritoneal exudate cells was studied. The extract inhibited the phagocytosis of opsonized sheep erythrocytes. This inhibition was both dose- and time-dependent and reverted 48 h after removing the extract from the culture medium. Furthermore, chemiluminescence in treated cells was also impaired using either receptor (opsonized zymosan) or post-receptor (PMA) stimuli.

Effect of Melia azedarach L. leaf extracts on human complement and polymorphonuclear leukocytes

The effect of the water extract of Melia azedarach L. (Meliaceae) leaves on human complement and polymorphonuclear leukocytes was investigated. This extract showed a strong anticomplementary activity, which was more pronounced in the classical pathway assay. The extract did not affect the phagocytic activity of polymorphonuclear leukocytes, nor the respiratory burst of these cells as measured by the nitro blue tetrazolium reduction assay.