Inhibitory effect of the flavonoid silymarin on the erythrocyte hemolysis induced by phenylhydrazine

The flavonoid silymarin, which is used as a therapeutical agent in the treatment of liver diseases, can inhibit the hemolysis and lipid peroxidation induced by phenylhydrazine on erythrocytes obtained from rats treated with the flavonoid. This effect is ascribed to the antioxidant properties as a free radical scavenger exhibited by the flavonoid. Silymarin failed to inhibit the glutathione depletion induced by phenylhydrazine on erythrocytes. It is proposed that the flavonoid acts at the membrane level of the cell avoiding the lipid peroxidative and fluidizing effect of phenylhydrazine.     

Inhibitory effect of oral Lactobacillus against oral pathogens

Aims: To determine the inhibitory effect of oral Lactobacillus against putative oral pathogens. Methods and Results: Total 357 strains comprising 10 species of oral Lactobacillus, Lactobacillus fermentum (195), Lactobacillus salivarius (53), Lactobacillus casei (20), Lactobacillus gasseri (18), Lactobacillus rhamnosus (14), Lactobacillus paracasei (12), Lactobacillus mucosae (12), Lactobacillus oris (12), Lactobacillus plantarum (11) and Lactobacillus vaginalis (10) were used as producer strains. Inhibitory effect against a panel of indicators, periodontitis‐ and caries‐related pathogens, was assessed. Most oral Lactobacillus was able to inhibit the growth of both periodontitis‐ and caries‐related pathogens. The strongest inhibitory activity was associated with Lact. paracasei, Lact. plantarum, Lact. rhamnosus, Lact. casei and Lact. salivarius. Lactobacillus SD1–SD6, representing the six species with the strong inhibitory effect, inhibited growth of Streptococcus mutans ATCC 25175 in the biofilm model. Also, it was demonstrated that growth of Strep. mutans was inhibited in a mixture with Lact. paracasei SD1. The inhibition was enhanced in acidic condition and 5% glucose. Conclusions: The results have shown that oral Lactobacillus SD1–SD6 showed a strong inhibitory effect against Strep. mutans and Streptococcus sobrinus, as well as, Gram‐negative periodontal pathogens Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans. Significance and Impact of the Study: The results indicated that Lactobacillus may be of benefit as probiotics for the prevention of oral diseases.     

Inhibitory effect of cinnamoyl compounds against human malignant cell line

In the present study, anti-proliferative effects of dietary polyphenolic compounds have been observed and demonstrated the strong anticancer efficacy of curcumin (CMN), an active constituent of dietary spice (turmeric) using human leukemia cancer cell line. CMN inhibited the proliferation of K562 leukemic cells by induction of apoptosis. The current study demonstrated synergy with combination of drug therapy, and suggested that combination of ferulic acid and cisplatin synergistically inhibited cellular proliferation. Cytotoxic synergy was observed independent of the sequence of addition of two drugs to cultured cells. The synergized growth inhibitory effect with cisplatin was probably associated with G2-M arrest in cell cycle progression. These findings suggested that among the cinnamoyl compounds, CMN was most potent and FER appeared to be a better modulating agent on human malignant cell line.     

The effect of oxidants on biomembranes and cellular metabolism

During the reductive process in the tissues, the aerobes generate a number of oxidants. Unless these oxidants are reduced, oxidative damage and cell death would occur. Oxidation of plasma membrane lipids leads to autocatalytic chain reactions which eventually alter the permeability of the cell. The role of oxidative damage in the pathophysiology of diabetic complications and ischemic reperfusion injury of myocardium, especially the changes in the channel activity which may lead to arrhythmia have been studied. Hyperglycemia activates aldose reductase which could efficiently reduce glucose to sorbitol in the presence of NADPH. Since NADPH is also aldose required by glutathione reductase for reducing oxidants, its diversion would lead to membrane lipid oxidation and permeability changes which are probably responsible for diabetic complications such as cataractogenesis, retinopathy, neuropathy etc. Antioxidants such as butylated hydroxy toluene (BHT) and also reductase inhibitors prevent or delay some of these complications. By using patch-clamp technique in isolated frog myocytes, we have shown that hydroxy radicals generated by ferrous sulfate and ascorbate as well as lipid peroxides such as t-butyl hydroperoxide facilitate the entry of Na⁺ by oxidizing Na⁺-channels. Increased intracellular Na⁺ leads to an increase in Na⁺/Ca²⁺ exchange. The increased Na⁺ concentration by itself may produce electrical disturbance which would result in arrhythmia. Increased Ca²⁺ may affect proteases and may help in the conversion of xanthine dehydrogenase to xanthine oxidase, consequently increased production of super oxide radicals. Increased membrane lipid peroxidation and other oxygen free-radical associated membrane damage in myocytes has been demonstrated.     

Inhibitory effect against Akt of cyclic dipeptides isolated from Bacillus sp

Among thirteen strains of the genus Bacillus isolated from Shrimp-jeotkal in our laboratory, a strain BA34 showing good antifungal activity against Phytophthora infestans in a previous experiment was tested for the inhibitory effect against Akt, protein kinase B. Since Akt is known to play an important role in controlling apoptosis, its inhibitors can be used as potential apoptosis-inducing agents in the treatment of cancer. Two active compounds were isolated and their structures were determined. They have similar structures, despite showing different inhibitory effects. In order to elucidate the reasons for these different effects, three-dimensional studies were carried out.     

Inhibitory effect of oligoribonucleotide phosphorodithioates against the 3'-exonuclease activity.

Oligoribonucleotides consisted of modified nucleotides at 3'-turmini were chemically synthesized on the solid phase method. Moreover, these analogues were investigated the stability in a prokaryotic cell-free translation system and the resistance against a few kind of nucleases containing 3'-exonuclease activity.     

Stimulation effect of carrageenan on enzymatic defense system of sweet basil against Cuscuta campestris infection

Sweet basil is an important medicinal plant used especially for therapeutical potentials. Sweet basil is a common host for Cuscuta campestris, which has a negative effect on infected plants. Therefore, natural friendly control of C. campestris seems to be useful. It has been shown that carrageenans can act as elicitors of plant defense responses. In this work, the effect of κ-carrageenans on protection against C. campestris and suppression of its invasion in basils were studied. Basils were sprayed with a solution of κ-carrageenan (1?g?L^?1), once a week, three times in total. Infection of basils with C. campestris was performed two days after the last carrageenan treatment. C. campestris stem and the leaves of basils were collected two weeks after C. campestris inoculation for biochemical studies. Treatment with carrageenan significantly increased shoot length and leaf area of basil and decreased C. campestris infestation by about 26%. The content of malondialdehyde, other aldehydes, hydrogen peroxide and lipoxygenase (LOX) activity increased significantly in basils parasitized by C. campestris. There were significant differences in phenylalanine ammonia lyase (PAL), catalase (CAT), superoxide dismutase (SOD) and peroxidase activity of parasitized basils by C. campestris compared with healthy basils. Carrageenan treatment of basils caused a significant increase in H₂O₂ content and the activity of PAL, CAT and SOD, but not of malondialdehyde, other aldehydes content and LOX, polyphenol oxidase (PPO) and peroxidases activity. The activated enzymatic defense system (PAL, PPO, CAT, SOD and peroxidase) in carrageenan-treated basils have a vital role in alleviating oxidative stress damage in infected plants, by removing excess reactive oxygen species and inhibiting LOX activity and lipid peroxidation that was observed in this study. Our results showed that the application of κ-carrageenan-induced beneficial effects in plants, with regard to growth stimulation and the activation of enzymatic defense system. Thus, carrageenan was recommended as a natural biostimulator for protection of plants against C. campestris.     

Inhibitory effect of antibodies against human chorionic gonadotropin on the growth of colorectal tumour cells

Human chorionic gonadotropin (hCG) was initially believed to be secreted exclusively by the embryo with its primary function being "rescue" of the corpus luteum. However, recently it has been found that the hormone (or its individual subunits) is also secreted by many cancers and that in many cases secretion is associated with poor patient prognosis. In this study, we assessed the presence of hCG in colorectal cancer cells (CCL-253) and evaluated the anti-tumour effects of anti-hCG antibodies in vitro and in vivo. Anti-hCG antibodies were reactive with CCL-253, as revealed by confocal immunoflourescence microscopy; both cell surface and intracellular expression were observed. Western blot analysis showed that antibodies appeared to interact with several moieties, indicating a level of cross-reactivity. Anti-hCG antiserum specifically reduced the viability of tumor cells and the addition of complement increased in vitro anti-tumor effects. In nude mice implanted with CCL-253 cells, administration of anti-hCG antiserum caused a significant reduction in tumor volume; all treated animals survived, while mortality was observed in control animals. Results suggest that anti-hCG antibodies can mediate significant anti-tumor activity both in vitro and in vivo and lend support to the rationale of anti-hCG immunization in the therapy of gonadotropin- sensitive cancers.     

Inhibitory effect of Abrus abrin-derived peptide fraction against Dalton's lymphoma ascites model

Peptides derived from larger molecules that are important modulators in cancer regression are becoming leads for development of therapeutic drugs. It has been reported that Abrus abrin, isolated from the seeds of Abrus precatorius, showed in vitro and in vivo antitumor properties by the induction of apoptosis. The present study was designed to evaluate the in vivo therapeutic effectiveness of abrin-derived peptide (ABP) fraction in Dalton's lymphoma (DL) mice model. The lethal dose (LD₅₀) of ABP was found to be 2.25 mg/kg body weight and further the acute toxicity was determined with sublethal doses in normal mice. The acute toxicity like body weight, peripheral blood cell count, lympho-hematological and biochemical parameters remained unaffected till 200 μg/kg body weight of ABP. The sublethal doses of ABP showed very significant growth inhibitory properties in vivo DL mice model. There were 24%, 70.8% and 89.7% reductions in DL cell survival in 25, 50 and 100 μg/kg body weight of ABP, respectively. Analysis of the growth inhibitory mechanism in DL cells revealed nuclear fragmentation, and condensation with the appearance of the sub-G₀/G₁ peak is indicative of apoptosis. Further, the Western blotting showed that apoptosis was mediated by the reduction in the ratio of Bcl-2 and Bax protein expression, and activation of caspase-3 through the release of cytochrome c in DL cells. Kaplan–Meier survival analysis showed an effective antitumor response (104.6 increase in life span (ILS) %) with a dose of 100 μg/kg body weight.     

Inhibitory effect of essential oils against herpes simplex virus type 2.

Essential oils from anise, hyssop, thyme, ginger, camomile and sandalwood were screened for their inhibitory effect against herpes simplex virus type 2 (HSV-2) in vitro on RC-37 cells using a plaque reduction assay. Genital herpes is a chronic, persistent infection spreading efficiently and silently as sexually transmitted disease through the population. Antiviral agents currently applied for the treatment of herpesvirus infections include acyclovir and its derivatives. The inhibitory concentrations (IC50) were determined at 0.016%, 0.0075%, 0.007%, 0.004%, 0.003% and 0.0015% for anise oil, hyssop oil, thyme oil, ginger oil, camomile oil and sandalwood oil, respectively. A clearly dose-dependent virucidal activity against HSV-2 could be demonstrated for all essential oils tested. In order to determine the mode of the inhibitory effect, essential oils were added at different stages during the viral infection cycle. At maximum noncytotoxic concentrations of the essential oils, plaque formation was significantly reduced by more than 90% when HSV-2 was preincubated with hyssop oil, thyme oil or ginger oil. However, no inhibitory effect could be observed when the essential oils were added to the cells prior to infection with HSV-2 or after the adsorption period. These results indicate that essential oils affected HSV-2 mainly before adsorption probably by interacting with the viral envelope. Camomile oil exhibited a high selectivity index and seems to be a promising candidate for topical therapeutic application as virucidal agents for treatment of herpes genitalis.     

Phytoalexins in defense against pathogens

Plants use an intricate defense system against pests and pathogens, including the production of low molecular mass secondary metabolites with antimicrobial activity, which are synthesized de novo after stress and are collectively known as phytoalexins. In this review, we focus on the biosynthesis and regulation of camalexin, and its role in plant defense. In addition, we detail some of the phytoalexins produced by a range of crop plants from Brassicaceae, Fabaceae, Solanaceae, Vitaceae and Poaceae. This includes the very recently identified kauralexins and zealexins produced by maize, and the biosynthesis and regulation of phytoalexins produced by rice. Molecular approaches are helping to unravel some of the mechanisms and reveal the complexity of these bioactive compounds, including phytoalexin action and metabolism.     

Physical exercise effect on erythrocyte metabolism

A group of 27 canoeists from the national team and 35 subjects beginning training in a sports discipline were subjected to investigations for determination of glucose utilization by erythrocytes, and the level of lactic acid in these cells and in serum. Furthermore, erythrocyte count and haematocrit value were determined in them. Both groups performed submaximal and maximal work on cycle ergometer. In the trained sportsmen the erythrocyte count and haematocrit value were higher already before exercise. During the exercise the increase in these values, as well as the rise in erythrocyte and serum lactic acid levels were again greater than in untrained freshmen. This difference was caused by the fact that the trained sportsmen performed twice as much work. Glucose utilization by erythrocytes (in vitro) was greatest after maximal exercise in both groups. The differences observed between both groups became manifest during exercise with a greater rise in glucose utilization by the erythrocytes obtained from the trained group. Fifteen minutes after the exercise this utilization fell in both groups below the value obtained before exercise. During the same time erythrocyte count and haematocrit returned to their initial levels.     

The effect of oxidants on neutrophil-mediated degradation of glomerular basement membrane collagen

The contribution of activated oxygen species to neutrophil-mediated degradation of basement membrane collagen was investigated. In preliminary experiments, pre-exposure of either albumin or glomerular basement membrane to neutrophil myeloperoxidase with H2O2 and chloride increased their susceptibility to proteolysis 2-3-fold. In the basement membrane model, neutrophils are stimulated by trapped immune complexes to adhere, produce oxidants and degranulate. Degradation, measured as the amount of hydroxyproline solubilised, was due to neutral proteinases, particularly elastase, and depended on cell number and the amount of proteinase released. Experiments with oxidant scavengers and inhibitors and with neutrophils from donors with chronic granulomatous disease or myeloperoxidase deficiency showed that oxidants did not affect degradation of the basement membrane when this was measured on a per cell basis. However, oxidative inactivation of the released granule enzymes occurred. Activities of elastase, beta-glucuronidase and lysozyme were 1.5-2-times higher in the presence of catalase, but were unaffected by superoxide dismutase or hydroxyl radical scavengers. Inactivation did not occur with chronic granulomatous disease or myeloperoxidase deficient neutrophils. When related to the activity of released elastase, or to other degranulation markers, collagen degradation was decreased in the presence of catalase, or with chronic granulomatous disease or myeloperoxidase deficient cells. This implies that the basement membrane was made more digestible by myeloperoxidase-derived oxidants, as occurred in the cell-free experiments. Taken together, the results indicate that neutrophil oxidants have two opposing effects. They increase the susceptibility of the collagen to proteolysis and inactivate the proteinases responsible.     

Estimation of antioxidant capacity against pathophysiologically relevant oxidants using Pyrogallol Red

Peroxynitrite and hypochlorite are oxidants relevant in many pathological situations. We propose a simple spectrophotometric assay to determine antioxidant capacity against hypochlorite and peroxynitrite based on protection against Pyrogallol Red decolorization. The assay can be performed on a microplate and requires minute amounts of material. Standard antioxidants show different reactivities for both oxidants. Antioxidant capacity of blood plasma (anticoagulated with EDTA) of healthy persons was found to be 559 ± 49 μmol/l and 11.6 ± 1.2 mmol/l of ascorbic acid equivalents for peroxynitrite and hypochlorite, respectively.     

Inhibitory action of chamaejasmin A against human HEP-2 epithelial cells: effect on tubulin protein

In this work, the anticancer activity of chamaejasmin A was studied by evaluating its in vitro cytotoxicity against several cell lines (CAL-27, UMSCC-1, UMSCCG19, HEP-2 and Vero cells) using the 3-(4,5)-dimethylthiazoly1)-3,5-diphenytetrazolium bromide assay. Results indicated chamaejasmin A shows more notable anticancer activity against HEP-2 cells, with IC₅₀ values of 3.48?μM. Furthermore, western blot analysis showed that chamaejasmin A is able to increase the expression of β-tubulin (TB), but not α-TB. In vivo, chamaejasmin A intake through gavage resulted in β-TB depolymerization inhibition in HEP-2 tumors. In silico simulations indicated that chamaejasmin A specifically interacts with the binding site which is located at the top of β-TB, thanks to the presence of strong hydrophobic effects between the core templates and the hydrophobic surface of the TB protein active site, associated with two strong H-bonds. The binding energy (E _inter) was calculated to be ?129.40?kcal?mol^?1. Results above suggest that chamaejasmin A possesses anti-cancer properties relating to β-TB depolymerization inhibition.