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Sideritis italica (Miller) Greuter et Burdet is a widespread Lamiacea in the Mediterranean region used in traditional medicine. Essential oils were antibacterial against nine ATCC and as many clinically isolated Gram-positive and Gram-negative bacterial strains. Antibacterial activity was also found against Helicobacter pylori: a dose-dependant inhibition was shown between 5 and 25 microg/ml. The antibacterial activity of the oils was expressed as MICs (minimum inhibitory concentrations) and MBCs (minimum bactericidal concentrations). At a concentration between 3.9 and 250 microg/ml the oils showed a significant antibacterial effect against both Gram-negative and Gram-positive bacteria. In particular the ATCC strains Pseudomonas aeruginosa (MIC=3.9 microg/ml and 7.8 for flowerheads and leaves, respectively), Proteus mirabilis (MIC=15.6 and 7.8 microg/ml), Salmonella typhi (MIC=7.8 microg/ml) and Proteus vulgaris (MIC=15.6 microg/ml) were the most inhibited. Only Pseudomonas aeruginosa showed MBC at a concentration between 62.6 and 125 microg/ml. The antioxidant activity of the essential oils was evaluated by two cell free colorimetric methods: ABTS and DMPD; leaf oil is more active (4.29 +/- 0.02 trolox equivalents and 4.53 +/- 0.67 ascorbic acid equivalents by ABTS and DMPD, respectively). Finally the antioxidant activity of the essential oils was also evaluated by their effects on human whole blood leukocytes (WB) and on isolated polymorphonucleate (PMN) chemiluminescence. Comparing the effects of the oils from leaves and flowerheads on both PMN and WB chemiluminescence emission, we found no significant differences. Essential oils showed a dose-dependent and linear inhibitory activity on isolated PMN as well as on WB CL emission when PMA-stimulated. On the contrary, the inhibitory activity on resting cells was nonlinear. Our data represent an answer to the continual demand for new antibiotics and antioxidants for the continuous emergence of antibiotic-resistant strains and the growing interest in the substitution of synthetic antioxidants with natural ones. Furthermore, our finding of antibacterial and antioxidant activities in the essential oils from Sideritis italica flowerheads and leaves validated the use of the plant for medical purposes.

Catechins and their derivatives are abundant flavanols in the plant kingdom. Usually, catechin activity correlates with chemical structure. We hypothesized that by adding hydrophobic groups to the native catechin, we could ameliorate penetration of the cell and make the derivatives more active than native molecule in inhibiting polymorphonuclear leucocyte (PMN) oxidative burst. This study was designed to compare the antioxidant activity of native catechin with that of (+)-3-propionylcatechin and (-)-3-Ovalerylcatechin esters by two cell-free colorimetric methods and by their effects on whole blood leucocytes as well as on isolated PMN chemiluminescence activity. The results showed that the colorimetric methods did not detect differences between catechins. On the contrary, cellular chemiluminescence studies showed that light emission by resting, as well as by phorbol myristate acetate (PMA)-stimulated PMNs and whole blood leucocytes was inhibited by catechin esters more intensively than native catechin. The compartmental chemiluminescence evaluation showed that the extracellular activity was similar with all catechins, while the intracellular activity was higher with esters. PMN pre-incubation, with catechins at various times before stimulation with PMA, enhanced the inhibitory activity of all compounds. Since the esterification with propionic or valeric acid increased the lipophilicity of (+)-catechin, we hypothesized that native and esterified catechins have different intracellular availability and therefore differ in effectiveness. An ancillary result obtained is that a single approach, chemical or cellular, is not sufficient to evaluate overall antioxidant activity in biological sytems. The results indicate that modified catechins may be very intriguing as possible future leucocyte modulating drugs, with possible applications in vascular and inflammatory diseases.

The flavonoids are a heterogeneous group of ubiquitous plant polyphenols that abound in the human diet and are endowed with several biological activities, including immunomodulating and antioxidant activities. The bioactivity of flavonoids is tightly correlated with their chemical structure and action mechanisms, mostly inhibitory, on enzymatic systems involved in cellular activation. The aim of this study was to evaluate the effects of acetonic extracts from Lunularia cruciata gametophytes and Feijoa sellowiana fruits on human phagocyte functions. A purified native flavonoid, a catechin, and two of its derivatives were also tested. The extract, and its flavonoid activity, was evaluated by analyzing luminol-dependent chemiluminescence emitted by human circulating phagocytes, at rest or activated by phorbol miristate acetate (PMA). The results demonstrate that both the raw extracts and flavonoids significantly inhibit CL emission by leukocytes, especially when these cells are activated by PMA. The antioxidant activity of flavonoids can be increased by changing the chemical structure of the native molecule.

Following the extraction of Castanea sativa with an aqueous solution of sulfuric acid (pH 3.0), the ethyl acetate soluble fraction was tested for its antibacterial and allelopathic activity. The extract was shown to have pronounced antibacterial effects against seven of the eight strains of Gram-positive and Gram-negative bacteria used (MIC in the range of 64-256 microg/ml and MBC in the range of 256-512 microg/ml). The active fraction was analyzed by TLC and HPLC showing the presence of rutin, hesperidin, quercetin, apigenin, morin, naringin, galangin and kaempferol. Standards of the identified flavonoids were tested against the same bacterial strains. The highest activity was shown by quercetin, rutin and apigenin. The allelopathic effect was tested against Raphanus sativus seed germination. The extract, quercetin, rutin and apigenin caused a decrease in the percentage of seed germination and root and epicotyl growth.

This study examines the anti-ulcerogenic activity of eugenol, a natural compound obtained from many natural sources. Gastric ulcers, induced by administration of two ulcerogenic agents, i.e. platelet activating factor (PAF) and ethanol, were dose-dependently and significantly reduced by eugenol (10-100 mg/kg, p.o.) pre-treatment. Eugenol was able to reduce not only the number of ulcers but also the gravity of lesions.

Dogs are the domestic reservoir of Leishmania infantum, a vector-borne intracellular protozoan agent of human visceral leishmaniasis. The role of polymorphonuclear leukocytes (PMNs) in the immune defence against this parasite has been poorly studied. We have investigated the function of peripheral blood PMNs in naive beagle dogs that have been naturally exposed to phlebotomine vectors in an area highly endemic for canine leishmaniasis, and found infected by Leishmania at the end of the transmission season. Whole blood phagocyte oxidative metabolism was assessed by a rapid method that determines a luminol-amplified chemiluminescence (CL) emission. This was evaluated using either a soluble stimulant, phorbol mirystate acetate (PMA), or phagocytic stimuli, such as zymosan unopsonized (ZYM) or opsonized with autologous serum (OPZ). In blood samples taken 2 months after exposure to Leishmania transmission, data on CL emission revealed a significant decrease of reactive oxygen intermediates (ROI) production in the presence of both PMA and ZYM, compared with blood samples obtained from dogs before exposure. On the contrary, no variations in CL emission were detected in presence of OPZ. Our data indicate that immunological changes occur early in canine leishmaniasis and confirm that the role of PMNs and their products need to be clarified., (Copyright 2000 John Wiley & Sons, Ltd.)

The role of polymorphonuclear leukocytes (PMNs) in the immune defence against intracellular bacteria has long been neglected. Only recently have studies begun to address this issue. In this study the behavior of peripheral PMNs in Bacillus Calmette-Guerin (BCG) vaccinated subjects was investigated. Twenty healthy and purified protein derivative-negative adults were studied before, and two and four months after, BCG administration. Luminol-amplified chemiluminescence (CL) emission was evaluated in whole blood phagocytes using a soluble stimulus, such as phorbol mirystate acetate, or particulates such as zymosan opsonized with homologous (OZH) or autologous (OZA) serum. Specific IgG, IgA and IgM against antigen -60 by ELISA, total immunoglobulin, C3 and C4 components of complement, were assessed by immunochemical tests. The results revealed a late heightened production of reactive oxygen intermediates in vaccinated subjects in presence of OZA and OZH. Our findings confirm that the role of PMNs and their mediators in immunoregulation of intracellular diseases needs to be re-evaluated., (Copyright 2000 John Wiley & Sons, Ltd.)

The present study was designed to evaluate the antibacterial and antioxidant activities of an aqueous extract from the tropical Feijoa sellowiana Berg. fruit which is widely used for human food. The extract was tested against gram-positive and gram-negative bacteria by a broth dilution test and on human whole blood leukocytes, as well as isolated neutrophils using a chemiluminescence (CL) assay. The extract inhibited bacterial growth; Pseudomonas aeruginosa, Enterobacter aerogenes and Enterobacter cloacae were the most sensitive. The fruit extract significantly decreased CL emission from human whole blood phagocytes and isolated polymorphonuclear leukocytes whether they were activated or not by soluble or phagocytic stimuli. F. sellowiana showed both antibacterial and antioxidant properties and therefore its extract might be used as a new multifaceted drug.

Dogs are the domestic reservoirs of zoonotic visceral leishmaniasis caused by Leishmania infantum. Early detection of canine infections evolving to clinically patent disease may be important to leishmaniasis control. In this study we firstly investigated the peripheral blood mononuclear cell (PBMC) response to leishmanial antigens and to polyclonal activators concanavalin A, phytohemagglutinin and pokeweed mitogen, of mixed-breed dogs with natural L. infantum infection, either in presymptomatic or in patent disease condition, compared to healthy animals. Leishmania antigens did not induce a clear proliferative response in any of the animals examined. Furthermore, mitogen-induced lymphocyte proliferation was found strongly reduced not only in symptomatic, but also in presymptomatic dogs suggesting that the cell-mediated immunity is suppressed in progressive canine leishmaniasis. To test this finding, naive Beagle dogs were exposed to natural L. infantum infection in a highly endemic area of southern Italy. Two to 10 months after exposure all dogs were found to be infected by Leishmania, and on month 2 of exposure they all showed a significant reduction in PBMC activation by mitogens. Our results indicate that suppression of the lymphoproliferative response is a common occurrence in dogs already at the beginning of an established leishmanial infection.

The effects of Lunularia cruciata (L.) Dum (Bryophyta) acetonic extract was studied in vitro by means of luminol-dependent chemiluminescence (CL) emission from human peripheral whole blood phagocytes and isolated polymorphonuclear leukocytes (PMNs). L. cruciata adult thalli underwent extraction with acetone. CL emission was evaluated in an automated luminometer, measuring the oxygen free-radical production by phagocytes incubated with opsonized zymosan (OZ) or phorbol myristate acetate (PMA), in absence or in presence of various concentrations of L. cruciata extract. The CL results indicated that L. cruciata induced significant changes in light emission from whole blood phagocytes, as well as isolated PMNs. Its inhibitory activity was more evident when resting isolated PMNs were studied. When the cells were activated, the greatest inhibitory effect was observed with PMA. The L. cruciata activity could be caused by several compounds, such as flavonoids and/or sesquiterpenes, present in the acetonic extract.

The antibacterial activity of extracts from various parts of plants (leaves, fruits and stems) was studied in Actinidia chinensis, Feijoa sellowiana and Aberia caffra. These are tropical plants used for food. The fruits (subdivided into skin, pulp and seeds), leaves and stems were separately extracted and tested, in triplicate, against eight Gram positive and Gram negative bacterial strains. All the extracts, except from the leaves of A. caffra, showed activity against all the strains employed. Inhibition of bacterial growth was tested against Na-cefotaxime, benzyl penicillin and tetracycline. The antibiotic activity of fruit resides essentially in the seeds. The antibacterial activity of extracts from vegetative plant parts was generally less active that from fruit extracts. The minimum inhibiting concentration (MIC) and minimum bactericidal concentration (MBC) were determined for all the extracts and showed exclusively bacteriostatic activity.

Three caffeoylquinic acids, isolated from the Peruvian plants Tessaria integrifolia and Mikania cordifolia that are used medicinally as anti-inflammatory agents, were tested for their activities on monocyte migration and superoxide anion production. 3,5-Di-O-caffeoylquinic and 4,5-di-O-caffeoylquinic acids exhibited an appreciable anti-inflammatory activity in vitro, while the tricaffeoyl derivative was inactive.

The pretreatment of epididymal spermatozoa with SV-IV, one of the major secretory protein produced by the epithelium of adult rat seminal vesicles, was found to markedly decrease their ability to induce in vivo peritoneal macrophage activation, measured as class II major histocompatibility complex surface antigen expression, superoxide anion production, phagocytic activity, and antigen presentation. In addition, the treatment of spermatozoa with SV-IV produced a significant decrease of their immunogenicity evaluated in vitro by [3H]thymidine incorporation in splenocyte/spermatozoon co-culture. The concurrent presence of SV-IV and transglutaminase, an enzyme secreted in large amounts from the rat anterior prostate, amplified these phenomena. The suppression of the epididymal sperm immunogenicity is suggested to be of crucial importance for the prevention of the immune response to the sperm introduced in the immunocompetent female genital tract during coitus.

SV-IV, a 9.8-kd protein isolated from rat seminal vesicle secretion, has been shown to have strong non-species-specific immunosuppressive, anti-inflammatory, antithrombotic, and antiphospholipase A2 properties. The present investigation was undertaken to determine the mechanism of action of its immunosuppressive effects. It was found that SV-IV is a potent inhibitor of interleukin-1 (IL-1) release from lipopolysaccharide (LPS)-activated human adherent monocytes and an effective inhibitor of IL-1-induced thymocyte proliferation. The ability of SV-IV to form a noncovalent dimeric association with IL-1 alpha but not with IL-1 beta, its ability to induce a marked decrease of IL-1 binding to its own receptors on the thymocyte surface, and its capacity to bind specifically to the macrophage plasma membrane might play an important role in the molecular mechanism of these inhibitory effects.

A crystalline silica (standard quartz DQ12 with particle size less than 5 micrometers) is able to stimulate in Balb/c mice the production of antibodies of various isotypes to the T-dependent antigen trinitrophenylated keyhole limpet hemocyanin. Under the same experimental conditions silica was not able to stimulate antibody response to the T-independent antigen trinitrophenylated Ficoll. These results support the possibility that adjuvanticity of silica is correlated to its effects on one or more of the various functions carried out by macrophages on immune responses.