A novel hypothesis for COVID-19 pathogenesis: Retinol depletion and retinoid signaling disorder.

The SARS-CoV-2 virus has caused a worldwide COVID-19 pandemic. In less than a year and a half, more than 200 million people have been infected and more than four million have died. Despite some improvement in the treatment strategies, no definitive treatment protocol has been developed. The pathogenesis of the disease has not been clearly elucidated yet. A clear understanding of its pathogenesis will help develop effective vaccines and drugs. The immunopathogenesis of COVID-19 is characteristic with acute respiratory distress syndrome and multiorgan involvement with impaired Type I interferon response and hyperinflammation. The destructive systemic effects of COVID-19 cannot be explained simply by the viral tropism through the ACE2 and TMPRSS2 receptors. In addition, the recently identified mutations cannot fully explain the defect in all cases of Type I interferon synthesis. We hypothesize that retinol depletion and resulting impaired retinoid signaling play a central role in the COVID-19 pathogenesis that is characteristic for dysregulated immune system, defect in Type I interferon synthesis, severe inflammatory process, and destructive systemic multiorgan involvement. Viral RNA recognition mechanism through RIG-I receptors can quickly consume a large amount of the body's retinoid reserve, which causes the retinol levels to fall below the normal serum levels. This causes retinoid insufficiency and impaired retinoid signaling, which leads to interruption in Type I interferon synthesis and an excessive inflammation. Therefore, reconstitution of the retinoid signaling may prove to be a valid strategy for management of COVID-19 as well for some other chronic, degenerative, inflammatory, and autoimmune diseases.

Protective activity of Hertia cheirifolia extracts against DNA damage, lipid peroxidation and protein oxidation.

CONTEXT: Hertia cheirifolia L. (Asteraceae), a perennial shrub widely distributed in Northern Africa, is traditionally used to treat inflammatory disorders. OBJECTIVE: The protective effect of methanol (Met E) and aqueous (Aq E) extracts of Hertia cheirifolia against DNA, lipid and protein oxidation was investigated. MATERIALS AND METHODS: Different concentrations (50-1000 µg/mL) of Hertia cheirifolia aerial part extracts were examined against DNA, lipid and protein oxidation induced by H2O2 + UV, FeSO4, and Fe3+/H2O2-ascorbic acid, respectively. The DPPH•, metal ion chelating, reducing power and ß-carotene bleaching tests were conducted. RESULTS: Both extracts were rich in polyphenols, flavonoids and tannins, and were able to scavenge DPPH• with IC50 values of 138 and 197 µg/mL, respectively. At 300 µg/mL, Aq E exerted stronger chelating effect (99%) than Met E (69%). However, Met E reducing power (IC50 = 61 µg/mL) was more than that of Aq E (IC50 = 193 µg/mL). Both extracts protected from ß-carotene bleaching by 74% and 94%, respectively, and inhibited linoleic acid peroxidation. The inhibitory activity of Aq E extract (64%) was twice more than that of Met E (32%). Interestingly, both extracts protected DNA against the cleavage by about 96-98%. At 1 mg/mL, Met E and Aq E restored protein band intensity by 94-99%. CONCLUSIONS: Hertia cheirifolia exhibits potent antioxidant activity and protects biomolecules against oxidative damage; hence, it may serve as potential source of natural antioxidant for pharmaceutical applications and food preservation. This is the first report on the protective activity of this plant against biomolecule oxidation.

Phenolic Content and Biomolecule Oxidation Protective Activity of Globularia alypum Extracts

ABSTRACT The protective activity of methanolic (Met E) and aqueous (Aq E) extracts of Globularia alypum L. (G. alypum) against DNA, lipid and protein oxidative damage was investigated. Moreover, the scavenging, chelating, and reducing power activities of the extracts were also evaluated. Phytochemical analysis was performed to determine phenolic compounds. Results showed that Met E and Aq E were rich in phenolic compounds, and were able to scavenge DPPH˙ with IC50 values of 48.61 µg/mL and 51.97 µg/mL, respectively. In addition, both extracts were able to chelate ferrous ions. At 300 μg/mL, the chelating activity was 97.53% and 91.02%, respectively. The reducing power of these extracts was also remarkable and concentration dependent. At 100 µg/mL, both extracts inhibited lipid peroxidatin by only 42.45% and 4.03%. However, the DNA oxidation damage was inhibited dose-dependently in the presence of G. alypum extracts. At 1 mg/mL, both extracts suppressed DNA cleavage by 83%-84%. The protein oxidation was also inhibited by G. alypum extracts. At 1 mg/mL, Aq E and Met E protected BSA fragmentation by 77%-99%. The overall results suggest that G. alypum extracts exerted antioxidant activity and protect biomolecules against oxidative damage; hence it may serve as a potential source of natural antioxidants.

UHPLC-ESI-MS/MS and GC-MS Analyses on Phenolic, Fatty Acid and Essential Oil of Verbascum pinetorum with Antioxidant, Anticholinesterase, Antimicrobial and DNA Damage Protection Effects.

This paper is the first phytochemical and ABTS cation radical decolorisation activity, cupric reducing antioxidant capacity, anticholinesterase and DNA damage protection effect of endemic Verbascum pinetorum (Boiss.) O. Kuntze. Phenolic profile of V. pinetorum were qualified and quantified by UHPLC-ESI-MS/MS analysis. Malic acid (47250.61±2504.28 µg/g) and luteolin (7651.96±527.98 µg/g) were found as most abundant compounds for metanol and acetone extracts, respectively. Fatty acid and essential oil compositions were determined by GC-MS analysis. The main components of fatty acid were found to be palmitic (27.1%) and stearic (22.1%) acids. The main compounds of the essential oil were cineole (16.9%) and α-selinene (16.4%). The acetone extract was found to be more active than BHT used as a standard in ß-carotene-linoleic acid test system. In DPPH free radical scavenging activity, the acetone and methanol extracts showed higher activity than BHT at all tested concentrations. The acetone, methanol and water extracts showed strong inhibition while the acetone extract showed better activity than BHT and α-tocopherol which were used as standards in ABTS cation radical scavenging and cupric reducing antioxidant capacity assays, respectively. All extracts were found to be inactive in antialzheimer activity. The acetone extract exhibited moderate antimicrobial activity against C. albicans. The methanol extract of V. pinetorum were found no significant effect on DNA cleavage protection.

Assessment of the Antioxidant Activity of Silybum marianum Seed Extract and Its Protective Effect against DNA Oxidation, Protein Damage and Lipid Peroxidation.

Antioxidant properties of ethanol extract of Silybum marianum (milk thistle) seeds was investigated. We have also investigated the protein damage activated by oxidative Fenton reaction and its prevention by Silybum marianum seed extract. Antioxidant potential of Silybum marianum seed ethanol extract was measured using different in vitro methods, such as lipid peroxidation, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing power assays. The extract significantly decreased DNA damage caused by hydroxyl radicals. Protein damage induced by hydroxyl radicals was also efficiently inhibited, which was confirmed by the presence of protein damage markers, such as protein carbonyl formation and by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The present study shows that milk thistle seeds have good DPPH free radical scavenging activity and can prevent lipid peroxidation. Therefore, Silybum marianum can be used as potentially rich source of antioxidants and food preservatives. The results suggest that the seeds may have potential beneficial health effects providing opportunities to develop value-added products.

The protective effect of pomegranate extract against cisplatin toxicity in rat liver and kidney tissue.

OBJECTIVES: The purpose of this study was to perform a histopathological investigation, at the light microscopy level, of the protective effects of pomegranate extract in cisplatin-induced liver and kidney damage in rats. MATERIAL AND METHODS: Twenty-eight adult male Wistar albino rats were randomly divided into four groups of seven animals: Group 1: Control; Group 2: Treated for 10 consecutive days by gavage with pomegranate juice (2 ml/kg/day); Group 3: Injected intraperitoneally with cisplatin (8 mg/kg body weight, single dose) onset of the day 5, and Group 4: Treated by gavage with pomegranate juice 10 days before and after a single injection of cisplatin onset of the day 5. After 10 days, the animals were sacrificed and their kidneys and liver tissue samples were removed from each animal after experimental procedures. Cisplatin-induced renal and hepatic toxicity and the effect of pomegranate juice were evaluated by histopatological examinations. RESULTS: In the kidney tissue, pomegranate juice significantly ameliorated cisplatin-induced structural alterations when compared with the cisplatin alone group. But in the liver tissue, although pomegranate juice attenuated the cisplatin-induced toxicity only in two rats, significant improvement was not observed. CONCLUSION: In conclusion, these results demonstrate that the anti-oxidant pomegranate juice might have a protective effect against cisplatin-induced toxicity in rat kidney, but not in liver. Pomegranate juice could be beneficial as a dietary supplement in patients receiving chemotherapy medications.

Chemical profile and biological activities of Veronica thymoides subsp. pseudocinerea.

CONTEXT: In Turkey, Veronica species (Plantaginaceae) have been used as a diuretic and for wound healing in traditional medicine. OBJECTIVE: To examine the fatty acid and essential oil profiles, the antioxidant, anticholinesterase, antimicrobial, and DNA damage effects of Veronica thymoides P.H. Davis subsp. pseudocinerea M.A. Fischer as a potential source of natural active compounds. MATERIALS AND METHODS: GC/MS was used to analyze essential oil and fatty acid obtained from whole plant. The antioxidant activity was evaluated by the ß-carotene-linoleic acid test system, DPPH-free and ABTS cation radicals scavenging, and cupric reducing antioxidant capacity assays. The anticholinesterase and antimicrobial activities were determined by Ellman and broth macrodillution methods, respectively. The effect of the methanol extract on DNA cleavage was investigated. RESULTS: Hexatriacontene (21.0%) was found to be the main constituent in essential oil, and linoleic acid (25.2%) and palmitic acid (20.6%) in fatty acid. Methanol extract demonstrated the best IC50 values in lipid peroxidation (49.81 ± 0.31 µg/ml) and DPPH-free radical scavenging activity (15.32 ± 0.17 µg/ml). Methanol and water extracts possessed strong ABTS cation radical scavenging activity with IC50 values 9.15 ± 0.28 and 8.90 ± 0.1 µg/ml, respectively. The acetone extract exhibited moderate butyrylcholinesterase inhibitory activity. The highest antimicrobial activity was determined in methanol extract against Escherichia coli with 31.25 µg/ml MIC value. Inhibition of methanol extract on plasmid DNA cleavage by OH radicals was found to be 93.32% at 500 µg/ml. CONCLUSION: The methanol extract having strong antioxidant and DNA damage effects could be investigated phytochemically to find natural active compounds.

The protective role of pomegranate juice against carbon tetrachloride-induced oxidative stress in rats.

Most pomegranate (Punica granatum Linn., Punicaceae) fruit parts are known to possess enormous antioxidant activity. The present study was carried out to determine the phenolic and flavonoid contents of Derik pomegranate juice and determine its effect against carbon tetrachloride (CCl4)-induced toxicity in rats. Animals were divided into four groups (n = 6): group I: control, group II: CCl4 (1 ml/kg), group III: CCl4 + pomegranate juice and group IV: CCl4 + ursodeoxycholic acid (UDCA). Treatment duration was 4 weeks, and the dose of CCl4 was administered once a week to groups II, III and IV during the experimental period. CCl4-treated rats caused a significant increase in serum enzyme levels, such as aspartate aminotransferase, alanine aminotransferase and total bilirubin, and decrease in albumin, when compared with control. Administration of CCl4 along with pomegranate juice or UDCA significantly reduces these changes. Analysis of lipid peroxide (LPO) levels by thiobarbutiric acid reaction showed a significant increase in liver, kidney and brain tissues of CCl4-treated rats. However, both pomegranate juice and UDCA prevented the increase in LPO level. Histopathological reports also revealed that there is a regenerative activity in the liver and kidney cells. Derik pomegranate juice showed to be hepatoprotective against CCl4-induced hepatic injury. In conclusion, present study reveals a biological evidence that supports the use of pomegranate juice in the treatment of chemical-induced hepatotoxicity.

Do 100- and 500-µT ELF magnetic fields alter beta-amyloid protein, protein carbonyl and malondialdehyde in rat brains?

Several studies still state that presently accepted safety standards for extremely low-frequency magnetic fields (ELF-MFs) do not provide adequate protection, and therefore the standards are still open to question. To help resolve this question, the aim of this study was to illuminate the interaction between biomolecules and ELF-MFs by investigating the effect of ELF-MFs on beta-amyloid protein (BAP), protein carbonyl (PC) and malondialdehyde (MDA) in rat brain. For this study, 30 adult male Sprague-Dawley rats were used, which were divided into two experimental groups and a sham exposed group. Rats in two experimental groups were exposed to 100- and 500-µT ELF-MFs (50 Hz) for 2 h/day for 10 months, which are the generally accepted safety standards for public and occupational exposures. The same procedures were applied to the rats in the sham group, but with the generator turned off. The results of this study showed that neither ELF-MFs used in this study altered BAP level significantly (p>0.05). However, PC and MDA levels were increased by the exposure to 100- and 500-µT ELF-MFs (p < 0.0001). In conclusion, both PC and MDA levels were altered by long-term exposure to either 100 or 500 µT ELF-MF. However, many further and more comprehensive studies will be required to elucidate the interaction mechanisms between ELF-MFs exposure and living organisms.

Protective effect of Öküzgözü (Vitis vinifera L. cv.) grape juice against carbon tetrachloride induced oxidative stress in rats.

The consumption of fruits plays an important role as a health protecting factor. Grapes (Vitis vinifera L.) are believed to have health benefits due to their antioxidant activity. Öküzgözü is the largest among the grape varieties grown in Turkey. Carbon tetrachloride (CCl4) causes free radical generation in many tissues such as the liver, kidney, heart, lung, testis, brain and blood. Ursodeoxycholic acid (UDCA) is the only drug to treat primary biliary cirrhosis, but the effects remain controversial. The aim of the present study is to investigate the protective effect of Öküzgözü grape juice or UDCA against tissue damage induced by CCl4 in rats. The amount of total phenolics and flavonoids were found to be 1208.00 +/- 43.00 µg ml⁻¹ as the gallic acid equivalent and 5.2 +/- 0.19 µg ml⁻¹ as the quercitin equivalent in Öküzgözü grape juice, respectively. In vivo administration of CCl4 caused a significant increase of various biochemical parameters such as alanine amino transferase (ALT), aspartate amino transferase (AST), total bilirubin (TB) and a decrease in albumin (ALB) levels in serum or an increase in malondialdehyde (MDA) levels in the tissues when compared to a control. Administration of CCl4 along with Öküzgözü grape juice or ursodeoxycolic acid (UDCA) significantly reduces these changes. Histopathalogical studies also support the protective effect of the extract. This study demonstrates the protective activity of Öküzgözü grape juice and thus scientifically supports the usage of this fruit in various traditional medicines for the treatment of tissue disorders. The effect of Öküzgözü grape juice was comparable with that of UDCA.

Effect of 900 MHz radio frequency radiation on beta amyloid protein, protein carbonyl, and malondialdehyde in the brain.

Recently, many studies have been carried out in relation to 900 MHz radiofrequency radiation (RF) emitted from a mobile phone on the brain. However, there is little data concerning possible mechanisms between long-term exposure of RF radiation and biomolecules in brain. Therefore, we aimed to investigate long-term effects of 900 MHz radiofrequency radiation on beta amyloid protein, protein carbonyl, and malondialdehyde in the rat brain. The study was carried out on 17 Wistar Albino adult male rats. The rat heads in a carousel were exposed to 900 MHz radiofrequency radiation emitted from a generator, simulating mobile phones. For the study group (n: 10), rats were exposed to the radiation 2 h per day (7 days a week) for 10 months. For the sham group (n: 7), rats were placed into the carousel and the same procedure was applied except that the generator was turned off. In this study, rats were euthanized after 10 months of exposure and their brains were removed. Beta amyloid protein, protein carbonyl, and malondialdehyde levels were found to be higher in the brain of rats exposed to 900 MHz radiofrequency radiation. However, only the increase of protein carbonyl in the brain of rats exposed to 900 MHz radiofrequency radiation was found to be statistically significant (p<0.001). In conclusion, 900 MHz radiation emitted from mobile/cellular phones can be an agent to alter some biomolecules such as protein. However, further studies are necessary.

Protective effect of Diyarbakir watermelon juice on carbon tetrachloride-induced toxicity in rats.

The present study was designed to evaluate the effect of Diyarbakir watermelon (Citrullus lanatus cv. Sürme) juice on lipid peroxidation states in rat liver, kidney and brain. In vivo administration of carbon tetrachloride (CCl(4)) once a week for 28 days caused a significant elevation of serum markers of liver damage, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (TB) and decrease in albumin when compared to the control group. However, administration of carbon tetrachloride along with watermelon juice or ursodeoxycolic acid (UDCA) significantly reduces these changes. Increased lipid peroxide (LPO) level was observed in the liver, kidney and brain tissues after CCl(4) administration. However, watermelon juice and UDCA treatment prevented the increase in LPO. The results indicated that watermelon juice protects the liver, kidney and brain tissues from experimental CCl(4) toxicity in rats and that the protective effect of watermelon juice may be due to its antioxidant activity and inhibition of lipid peroxide formation. In conclusion, present study reveals biological evidence that supports the use of watermelon juice in the treatment of chemical-induced hepatotoxicity.

Malondialdehyde (MDA) and protein carbonyl (PCO) levels as biomarkers of oxidative stress in subjects with familial hypercholesterolemia.

OBJECTIVE: Familial hypercholesterolemia (FH) is clinically characterized by elevated total and low-density lipoprotein (LDL) cholesterol levels in plasma, which has high risk for developing atherosclerosis. Increased oxidative stress (OS) and FH have been related to atherosclerosis. The study aims to evaluate oxidative stress in patients with hypercholesterolemia by measuring lipid peroxidation and protein carbonyl (PCO) levels in these patients. PCO in these patients may provide a new diagnostic biomarker for oxidative damage in atherosclerosis. DESIGN AND METHOD: Total cholesterol (Tc), low-density lipoprotein-cholesterol (LDL-c), triglyceride (TG), high-density lipoprotein-cholesterol (HDL-c), lipoprotein(a) (Lp-a) levels and carotid intima-media thickness were measured to evaluate characteristics of patients (11 homozygous and 25 heterozygous) with FH. 25 age-gender-BMI matched healthy control subjects were included in the study for comparison. RESULTS: MDA and PCO levels were significantly higher in homozygous patients compared with those of heterozygous and controls and it was found that they are positively correlated with LDL-c, Tc, Lp-a and IMT while negatively correlated with HDL-c. The heterozygous group also had significantly higher MDA and PCO levels compared with controls. CONCLUSION: The data obtained could be important for understanding the alterations presented by FH and could be related to their increased risk of developing atherosclerosis. To our knowledge, measurements of PCO in patients with FH are not recorded before and this may be used as a biomarker for protein oxidation, which may play a role in the increased cardiovascular risk of patients with FH.

Is there a role for antioxidants in prevention of pulmonary hypoplasia in nitrofen-induced rat model of congenital diaphragmatic hernia?

BACKGROUND/PURPOSE: Many studies suggest a role for antioxidants in the prevention of lung hypoplasia in nitrofen-induced rat models with congenital diaphragmatic hernia (CDH). This study investigates the oxidative status and the histological outcome of prenatal administration of vitamins E and C with synergistic effect, and effect of N-acetylcysteine (NAC) to improve lung maturation of nitrofen-induced rats. METHODS: CDH was induced by maternal administration of a single oral dose of nitrofen on day 9.5 of gestation, and the Sprague-Dawley rats were randomly divided into five groups: nitrofen (N), nitrofen + vitamin C (NC), nitrofen + vitamin E (NE), nitrofen + vitamin C + vitamin E (NCE) and nitrofen + NAC (NNAC). A control group in which only vehicle was administered was included. Cesarean section was performed on day 21. Body weight (BW) and total lung weight (LW) of all fetuses with CDH were recorded; lung histological evaluation was performed, and protein content of lungs, determination of thiobarbituric acid reactive substances, and the protein carbonyls in tissue samples were determined. RESULTS: A total of 133 rat fetuses with CDH were investigated. The body weight and the lung weight of fetuses of all groups that were exposed to nitrofen were significantly decreased than of the control group (P < 0.05). The animals exposed to nitrofen with different antioxidants showed increased protein levels in lung tissue. However, in the NCE and the NNAC groups, protein levels were significantly increased than in the others. Malondialdehyde levels significantly decreased in the NCE and the NNAC groups when compared with the NC and the NE groups. In addition, the NCE and NNAC groups decreased protein oxidation to control levels, and no significant difference was observed between control and these two antioxidants groups. The N, NC, NE and NNAC groups showed minimal improvement in lung histology; the NCE groups showed the most improvement in lung histology when compared with the other nitrofen plus antioxidant groups. CONCLUSION: Prenatal administration of NAC and vitamin E in combination with vitamin C represented the best effects to avoid oxidative damage and protein content of the lungs in rat pups with CDH at birth.

Extremely low frequency magnetic fields cause oxidative DNA damage in rats.

PURPOSE: To detect the genotoxic effects of extremely low frequency (ELF) -magnetic fields (MF) on oxidative DNA base modifications [8-hydroxyguanine (8-OH-Gua), 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua) and 4,6-diamino-5-formamidopyrimidine (FapyAde)] in rat leucocytes, measured following exposure to ELF-MF. MATERIALS AND METHODS: After exposure to ELF-MF (50 Hz, 100 and 500 microT, for 2 hours/day during 10 months), DNA was extracted, and measurement of DNA lesions was achieved by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS). RESULTS: Levels of FapyAde, FapyGua and 8OHdG in DNA were increased by both 100 microT and 500 microT ELF-MF as compared to a cage-control and a sham group; however, statistical significance was observed only in the group exposed to 100 microT. CONCLUSION: This is the first study to report that ELF-MF exposure generates oxidatively induced DNA base modifications which are mutagenic in mammalian cells, such as FapyGua, FapyAde and 8-OH-Gua, in vivo. This may explain previous studies showing DNA damage and genomic instability. These findings support the hypothesis that chronic exposure to 50-Hz MF may be potentially genotoxic. However, the intensity of ELF-MF has an important influence on the extent of DNA damage.

Comparison of the effects of maternal protein malnutrition and intrauterine growth restriction on redox state of central nervous system in offspring rats.

Both maternal protein malnutrition and intrauterine growth restriction (IUGR) have deleterious effects on brain development, but a comparison of these effects has not been previously reported. The objectives of this study were to investigate and compare the effects of both factors on the oxidative status of the central nervous system (CNS), including the spinal cord, in offspring rats. We evaluated various parameters of oxidative status and antioxidant enzyme activities of superoxide dismutase and catalase (CAT) in different regions of the CNS from 60-day-old rats subjected to prenatal and postnatal protein restrictions [middle protein restriction 12%, severe protein restriction (SPR) 4%] or IUGR produced by uterine artery ligation. Furthermore, we compared these study groups to each other and to control rats fed an isocaloric 24% protein diet. Results were analyzed using one-way ANOVA followed by Tukey's post hoc test. Both protein restrictions and IUGR altered various parameters of oxidative status. In all evaluated structures, protein restrictions resulted in increases in thiobarbituric acid-reactive substances level and index of lipid peroxidation (P<0.001), and in decreases in antioxidant enzyme activities (P<0.005). IUGR also increased lipid peroxidation levels in the blood samples (P<0.04) and protein oxidative damage in the cerebellum and cerebral cortex (P<0.005); however, no effects were detected on the spinal cord. The greatest decrease in CAT activity was in the cerebellum of rats fed with SPR diet (P<0.001). This study suggests that not only severe but also middle protein malnutrition have deleterious effects on CNS structures, including the spinal cord. Protein restriction has a greater effect on the redox state of the CNS than IUGR.

The effect of ethanol extract of Hypericum lysimachioides on lipid profile in hypercholesterolemic rabbits and its in vitro antioxidant activity.

Hypercholesterolemia, high cholesterol diet and oxidative stress increase serum total cholesterol and LDL cholesterol levels resulting in increased risk for development of atherosclerosis. Antioxidants play an important role in inhibiting and scavenging radicals, thus providing protection to humans against infectious and degenerative diseases. Literature shows that the antioxidant activity is high in medicinal plants. Realizing the fact that, this study was carried out to determine the effect of ethanol extract of Hypericum lysimachioides Boiss var lysimachioides (Guttifera) on serum lipid levels and serum lipid peroxidation in hypercholesterolemic rabbits. The rabbits were divided into four groups and these groups were fed with diets containing standard laboratory diet (Group I), standard laboratory diet and ethanol extracts of H. lysimachioides (HL) (50mg/kg body weight) (Group II), standard laboratory diet, ethanol extracts of HL (50mg/kg body weight) and cholesterol (100mg/kg body weight) (Group III), and finally standard laboratory diet and cholesterol (100mg/kg body weight) (Group IV), for 5 weeks. Feeding cholesterol increased serum cholesterol and LDL cholesterol levels significantly in Group IV as compared to the other groups. Ethanol extract of HL with high cholesterol diet significantly lowered LDL cholesterol and total cholesterol levels in the rabbits of Group III as compared to the Group IV. The level of serum triacylglycerol was found to be similar to all comparison groups. HDL cholesterol levels were also increased significantly in Groups II and III as compared to Group IV. Statistically significant difference was found in Group IV as compared to all other groups. The ethanol extract of HL with high cholesterol diet significantly lowered the serum MDA levels in the rabbits of Group III compared to the Group IV. The histopathological findings confirmed that the ethanol extract of HL restrained the progression of the hydropic degeneration and fatty changes in the liver and some atherosclerotic lesions in the aorta. The in vitro antioxidant activities of ethanol extract of HL was also evaluated. The free radical-scavenging properties of HL (IC(50)=28 microg/ml) were studied using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay system. Since plant phenolic compound is one of the phytochemicals possessing radical scavenging activity, the amount of total phenolic compound was also determined in ethanol extract of HL and total phenolic content of one-milligram HL ethanol extract was equivalent to 307 microg of gallic acid. Total antioxidant activity of ethanol extract of HL was tested by using ferric thiocyanate (FTC) and thiobarbituric acid (TBA) methods. Antioxidative activities of ethanol extract of HL was found to be comparable with Vitamin E. In conclusion, the use of this extract could be useful in the management of cardiovascular disease in which atherosclerosis is important.

Compositions and antimicrobial activities of the essential oils of two Hypericum species from Turkey.

The chemical compositions of essential oils obtained from Hypericum hyssopifolium var. microcalycinum and Hypericum lysimachioides var. lysimachioides were analysed by using GC and GC-MS. Caryophyllene oxide was found to be the major component. The essential oils of both Hypericum species showed antimicrobial activity against nine microorganism at a concentration of 60 to 80 microg/ml.

Unusual genetic organization of a functional type I protein secretion system in Neisseria meningitidis.

Proteins secreted by Neisseria meningitidis are thought to play important roles in the pathogenesis of meningococcal disease. These proteins include the iron-repressible repeat-in-toxin (RTX) exoprotein FrpC. Related proteins in other pathogens are secreted via a type I secretion system (TOSS), but such a system has not been demonstrated in N. meningitidis. An in silico search of the group B meningococcal genome suggested the presence of a uniquely organized TOSS. Genes encoding homologs of the Escherichia coli HlyB (ATP-binding), HlyD (membrane fusion), and TolC (outer membrane channel) proteins were identified. In contrast to the cistronic organization of the secretion genes in most other rtx operons, the hlyD and tolC genes were adjacent but unlinked to hlyB; neither locus was part of an operon containing genes encoding putative TOSS substrates. Both loci were flanked by genes normally associated with mobile genetic elements. The three genes were shown to be expressed independently. Mutation at either locus resulted in an inability to secrete FrpC and a related protein, here called FrpC2. Successful complementation of these mutations at an ectopic site confirmed the observed phenotypes were caused by loss of function of the putative TOSS genes. We show that genes scattered in the meningococcal genome encode a functional TOSS required for secretion of the meningococcal RTX proteins.

Small molecules that mimic the thiol-triggered alkylating properties seen in the natural product leinamycin.

Reaction of the antitumor agent leinamycin with cellular thiols results in conversion of the natural product to a DNA-alkylating episulfonium alkylating agent via an intriguing sequence of chemical reactions. To establish whether the chemistry first seen in leinamycin represents a general motif that can function in various molecular frameworks, construction of greatly simplified analogues containing only the "core" funcional groups anticipated to be necessary for thiol-triggered generation of an alkylating agent was undertaken. For this purpose, the "stripped-down" leinamycin analogue 7-(3-methyl-but-2-enyl)-1-oxo-1H-lambda4-benzo[1,2]dithiol-3-one (4) was synthesized. Treatment of 4 with thiol under several different conditions results in efficient conversion of the compound to cyclized 2,3-dihydro-benzo[b]thiophene-7-carboxylic acid products (13) that are envisioned to arise from Markovnikov addition of solvent to an intermediate episulfonium ion (14). Thus, the relatively simple molecule 4 is able to mimic the thiol-triggered alkylating properties displayed by the natural product leinamycin. This work helps define why the core functional groups required thiol-accelerated generation of an alkylating intermediate from leinamycin and indicates that substantially altered analogues of the natural product may retain alkylating properties. In a broader context, the results provide evidence that the unique cascade of chemical reactions first seen in the context of leinamycin represents a general motif that can operate in a variety of molecular frameworks.