Effect of ascorbic acid on airway responsiveness in ovalbumin sensitized guinea pigs

The effects of vitamin C on respiratory, allergic and immunological diseases: an experimental and clinical-based review

Vitamin C is used in modern medicine supplements for treatment of various disorders associated with oxidative stress, inflammation and immune dysregulation. In this review article, experimental and clinical results regarding the effects of vitamin C on respiratory immunologic, and allergic diseases are reviewed. Various databases and appropriate keywords are used to search the effect of vitamin C on respiratory diseases until the end of May 2022. Books, theses and articles were included. These studies assessed the effects of vitamin C on respiratory disorders including asthma, chronic obstructive pulmonary disease (COPD), lung infection and lung cancer. Vitamin C showed relaxant effect on tracheal smooth muscle via various mechanisms. The preventive effects of vitamin C were mediated by antioxidant, immunomodulatory and anti-inflammatory mechanisms in the experimental animal models of different respiratory diseases. Some clinical studies also indicated the effect of vitamin C on lung cancer and lung infections. Therefore, vitamin C could be used a preventive and/or relieving therapy in respiratory diseases.

Ethno-medicinal study of Artemisia ordosica Krasch. (traditional Chinese/Mongolian medicine) extracts for the treatment of allergic rhinitis and nasosinusitis

ETHNOPHARMACOLOGICAL RELEVANCE

Artemisia ordosica Krasch. (AOK) has been used for rheumatic arthritis, cold headache, sore throat, etc. in traditional Chinese/Mongolian medicine and is used for nasosinusitis by local Mongolian "barefoot" doctors. Up to now, their mechanisms are still unclear.

AIM

To evaluate the in vivo anti-inflammatory and allergic rhinitis (AR) alleviating effect as well as in vitro antimicrobial activities of AOK extracts to verify its ethno-medicinal claims.

MATERIALS AND METHODS

Crude extracts (methanol/95%-ethanol/ethyl acetate) of AOK root/stem/leaf and fractions (petroleum ether/ethyl acetate/n-butanol/aqueous) of AOK root extract were prepared. Xylene-induced ear swelling model in mouse and ovalbumin (OVA)-induced AR model in guinea pig were established. Ear swelling degrees of mice were measured. The numbers of rubbing movement and sneezes of guinea pigs were counted to evaluate the symptoms of AR. The serum levels of histamine, INF-γ, IL-2/4/10, and VCAM-1 were measured by ELISA assay. The histological changes of nasal mucosa were investigated by light microscope after H&E staining. Antimicrobial activities of AOK extracts were also tested. LC-MS/MS analysis was performed to characterize the constituents of active extract and molecular docking was conducted to predict the biological mechanism.

RESULTS

In ear-swelling model, extract (100.00 mg/kg) from the ethyl acetate layer of 95% ethanol (100.00 mg/kg) showed better swelling inhibition in mice than positive control (dexamethasone, 191.91 mg/kg). In AR model, extract from the ethyl acetate layer of 95% ethanol significantly alleviated the AR symptoms in guinea pigs, decreased the serum levels of histamine, INF-γ, IL-2/4/10, and VCAM-1, and reduced the infiltration of eosinophil in nasal mucosa. For Staphylococcus aureus, the ethyl acetate extract of AOK stem showed the highest inhibition (MIC=1.25 mg/mL), for Escherichia coli, n-butanol layer of 95% ethanol extract of AOK root showed the highest inhibition (MIC=15.00 mg/mL), for Candida glabrata, 95%-ethyl acetate extract of AOK leaf showed the best inhibition (MIC=0.064 mg/mL), while ethyl acetate and n-butanol layers showed similar inhibition on MRSA (MIC=7.50 mg/mL). LC-MS/MS characterization showed that dicaffeoylquinic acids account for more than 30% of ethyl acetate layer of AOK extract. Dicaffeoylquinic acids bind with histamine-1 receptor with high affinities and interesting modes.

CONCLUSIONS

Extracts from AOK had interesting anti-inflammatory activity in mice, alleviating effect against OVA-induced AR in guinea pigs, and antimicrobial activities in vitro, which support the ethno-medicinal use of it. The main constituents in ethyl acetate layer of AOK root extract are dicaffeoylquinic acids and could bind with histamine-1 receptor well. These findings highlighted the importance of natural product chemistry study of AOK.

Prophylactic effect of rosmarinic acid on tracheal responsiveness, white blood cell count and oxidative stress markers in lung lavage of sensitized rats

BACKGROUND

Rosmarinic acid (RA) as an active component of several medicinal plants, has shown anti-inflammatory and anti-oxidant effects. In this study, the effect of RA on tracheal responsiveness (TR), lung inflammatory cells, oxidant biomarkers in sensitized rats were evaluated.

METHODS

TR to methacholine and ovalbumin (OVA) as well as total and differential white blood cell (WBC) count and levels of nitrogen dioxide, nitrate, malondialdehyde, thiol, superoxide dismutase, and catalase in bronchoalveolar lavage fluid were measured in control (group C) rats, sensitized animals to OVA and given drinking water alone (group S), S groups receiving drinking water containing three concentrations of RA (0.125, 0.250 and 0.500 mg/mL) and dexamethasone (1.25 μg/mL), (n = 6 in each group).

RESULTS

Increased TR to methacholine and OVA, total WBC count, percentages of eosinophils, monocytes, neutrophils and levels of oxidant biomarkers but decreased other measured parameters were observed in group S compared to group C. Percentages of lymphocytes and antioxidant biomarkers were significantly increased but other measured parameters were significantly decreased in S group treated with dexamethasone and in rats treated with the two higher concentrations of RA compared to S group. The effect of RA medium concentration on percentage of eosinophils and RA high concentration on total WBC count and percentages of eosinophils and lymphocytes, were significantly higher than those of dexamethasone.

CONCLUSION

These results showed the concentration-dependent effect of RA on tracheal responses, lung inflammatory cells and oxidant-antioxidant parameters which was comparable to that of dexamethasone at used concentrations in sensitized rats.

Effect of Zataria multiflora Extract on Total and Differential White Blood Cell Count and Endothelin Level in Blood of Ovalbumin Sensitized Guinea Pigs

OBJECTIVE

To investigate the effect of hydro-ethanolic extract of Zataria multiflora (Z. multiflora) on endothelin level, total and differential white blood cells (WBC) count of sensitized guinea pigs.

METHODS

Five groups of guinea pigs sensitized to ovalbumin (OA) were given drinking water alone (group S), drinking water containing three concentrations of Z. multiflora (0.2, 0.4 and 0.8 mg/mL as groups S+Z1, S+Z2 and S+Z3) and dexamethasone (group S+D), n=6 for each group. The endothelin levels as well as total and differential WBC count in blood of sensitized and control guinea pigs were evaluated using enzyme linked immunosorbent assay method, and hemocytometer and Wright-Giemsa's staining of blood sample smear respectively.

RESULTS

Blood endothelin levels, total and most differential WBC count were increased but lymphocytes decreased in sensitized animals compared to controls (allP <0.01). In groups S+D, S+Z2 and S+Z3 endothelin level, total and differential WBC counts were significantly improved compared with group S (P <0.01). Although, all measured parameters in group S+Z1 was lower than group S+D (P <0.01), some parameters in group S+Z3 were greater than in group S+D (P <0.05 toP <0.01).

CONCLUSION

The results showed an anti-inflammatory effect of Z. multiflora extract in sensitized guinea pigs, which may suggest a therapeutic potential for the plant on asthma.

The Effect of Zataria multiflora and its Constituent, Carvacrol, on Tracheal Responsiveness and Lung Pathology in Guinea Pig Model of COPD

The effects of Zataria multiflora (Z. multiflora) and its constituent, carvacrol, in guinea pigs model of chronic obstructive pulmonary disease (COPD) were examined. Animals were divided into control, COPD, COPD + drinking water containing three concentrations of extract of Z. multiflora (0.4, 0.8 and 1.6 mg/ml), COPD + drinking water containing three concentrations of carvacrol (60, 120 and 240 µg/ml) and COPD + dexamethasone (50 µg/ml). COPD was induced by exposing animals to cigarette smoke for 3 months. Emphysema as a pathological change of the lung and tracheal responsiveness were measured (n = 5 for control and COPD groups and n = 6 for another groups). Tracheal responsiveness (p < 0.05) and emphysema were significantly increased (p < 0.001) in COPD compared to the control group. Tracheal responsiveness in COPD groups treated with two higher concentrations of the Z. multiflora and three concentrations of carvacrol, and emphysema in treated with highest concentration of Z. multiflora and carvacrol were significantly improved compared to COPD group. Studied parameters were also significantly improved in the treated group with dexamethasone compared to COPD animals (p < 0.05 to p < 0.01). The results indicated a preventive effect of Z. multiflora extract and its constituent, carvacrol, on tracheal responsiveness and pathological changes of the lung.

The extract of Zataria multiflora affect tracheal responsiveness, serum levels of NO, nitrite, PLA2, TP and histamine in sensitized Guinea pigs

ETHNOPHARMACOLOGICAL RELEVANCE

Different therapeutic effects for Zataria multiflora have been described in Iranian traditional medicine. In addition anti-inflammatory and anti-oxidant effects of this plant were previously described. The effect of the extract of Zataria multiflora on tracheal responsiveness (TR) and inflammatory mediators of sensitized guinea pigs was examined.

MATERIALS AND METHODS

Five groups of sensitized guinea pigs to ovalbumin (OA) were given drinking water alone, drinking water containing three concentrations of the extract and dexamethasone. TR to methacholine and OA, serum levels of NO, nitrite, PLA2, TP and histamine were measured (n=6, for each groups).

RESULTS

TR to methacholine and OA, serum levels of NO, nitrite, PLA2, TP and histamine were increased in sensitized animals compared to control group (p<0.05 to p<0.001). Treatment of sensitized animals with dexamethasone and most concentration of the extract lead to significantly decrease in all measured parameters compared to sensitized group (p<0.05 to p<0.001) except TP and histamine levels in treated group with dexamethasone.

CONCLUSION

These results showed a preventive effect of the extract of Zataria multiflora on tracheal responsiveness, serum level of NO, nitrite, total protein, PLA2 and histamine in sensitized guinea pigs which was equal or even more potent than dexamethasone at used concentrations.

Adipose-derived stromal cell therapy affects lung inflammation and tracheal responsiveness in guinea pig model of COPD

The effects of adipose derived stromal cells (ASCs) were evaluated on tracheal responsiveness and biochemical parameters in guinea pigs model of chronic obstructive pulmonary disease (COPD). Thirty six guinea pigs were divided into 6 groups including: Control, COPD, COPD+intratracheal delivery of PBS (COPD+ITPBS), COPD+intravenous delivery of PBS (COPD+IVPBS), COPD+intratracheal delivery of ASCs (COPD+ITASC) and COPD+intravenous injection of ASCs (COPD+IVASC). COPD was induced by exposing animals to cigarette smoke for 3 months. Cell therapy was then performed and after 14 days, tracheal responsiveness, concentration of interleukin-8 (IL-8) in serum and broncho-alveolar lavage fluid (BALF), as well as total and differential white blood cells (WBC) counts were evaluated. Tracheal responsiveness, total WBC counts, neutrophil and eosinophil percentage in BALF as well as concentration of IL-8 in serum and BALF significantly increased but lymphocyte percentage decreased in COPD compared to the control group (P<0.05 to p<0.001). Cell therapy was able to restore the tracheal hyper-responsiveness and the increased IL-8 concentration in serum and BALF of COPD-ITASC but not COPD-IVASC animals (P<0.05 for all cases). Total WBC in BALF also showed a significant decrease in both treated groups and the percentages of eosinophils, neutrophils and lymphocytes in BALF were reversed in COPD-ITASC compared to COPD-ITPBS animals (P<0.05 to P<0.001). Therefore, intratracheal cell therapy with ASC can decrease tracheal hyperresponsiveness and lung inflammation in cigarette smoke induced-COPD which may be helpful in attenuation of the severity of disease in patients suffering from COPD.

Fibronectin regulation by vitamin C treatment in kidneys of nicotinic mice offspring

Background:

Maternal cigarette smoking causes health risks and developmental defects in the offspring. So far, many studies have been conducted to suppress the effects of nicotine. However, the effects of coadministration of vitamin C and nicotine on extracellular matrix have not gained enough attention.

Objectives:

This study decided to investigate the effects of vitamin C on fibronectin expression in kidneys of mice offspring, treated with nicotine.

Materials and Methods:

Eighteen female pregnant BALB/c mice were selected; six mice in the experimental group 1 (exp 1) received nicotine (3 mg/kg/day), six mice in the experimental group 2 (exp 2) received 3 mg/kg/day nicotine and 9 mg/kg/day vitamin C simultaneously, and six were used as the control group and received 3 mL/kg/day normal saline via intraperitoneal (IP) injection parallel to other groups, since the 6th day of gestation to the end of prenatal period. In the first days of delivery, fibronectin content of neonatal kidneys was studied by immunohistochemistry (IHC) assay and gene expression was studied by the real-time PCR.

Results:

IHC results showed that fibronectin reaction significantly increased in proximal convoluted tubules of exp 1 compared with the control offspring; on the other hand, fibronectin reaction decreased in the mice offspring of exp 2. Gene expression results showed that fibronectin expression in the exp 1 offspring significantly increased compared with the control ones and fibronectin expression decreased in the mice offspring of exp 2.

Conclusions:

This study revealed that vitamin C could reduce the fibronectin accumulation effects of nicotine on kidney.

The preventive effects of natural adjuvants, G2 and G2F on tracheal responsiveness and serum IL-4 and IFN-γ (th1/th2 balance) in sensitized guinea pigs

OBJECTIVE

The effects of natural adjuvants on lung inflammation and tracheal responsiveness were examined in sensitized guinea pigs.

METHODS

The responses of guinea pig tracheal chains and the serum levels of interleukin-4 and interferon-gamma were examined in control pigs and three other groups of guinea pigs: the sensitized group and two other sensitized groups treated with either adjuvant G2 or adjuvant G2F (n=7 for each group). Sensitization of the animals was achieved by injection and inhalation of ovalbumin.

RESULTS

The results showed that sensitized animals had increased tracheal responsiveness and increased serum levels of interleukin-4 and interferon-gamma compared to controls (p<0.05 to p<0.001). Treatments with either G2 or G2F prevented the increase in tracheal responsiveness and serum interleukin-4 (p<0.01 to p<0.001). However, the serum levels of interferon-gamma and the interleukin-4-to-interferon-gamma ratio was increased in the treated groups (p<0.001 for all cases).

CONCLUSIONS

These results indicate important preventive effects of two natural adjuvants, particularly G2, on the changes in tracheal responsiveness, serum cytokines and the interleukin-4-to-interferon-gamma ratio (T helper 1/T helper 2 balance) in sensitized guinea pigs.

The effect of natural adjuvants on pathological changes in sensitized Guinea pig lungs

Background:

Anti-inflammatory effect of natural adjuvants has been reported. Lung inflammation is the most characterized pathological feature in asthma.

Objectives:

The effects of three natural adjuvants (PC, G2, and G2F registered as a patent in the Iranian Patent Office) on sensitized guinea pigs lungs were examined in the present study.

Materials and Methods:

Lung pathological changes were examined in control and five groups of randomly divided guinea pigs including: sensitized animals (S, receiving normal saline, 0.5 ml i.p.); sensitized animals treated with adjuvant PC; G2F (0.1 ml i.p. for both cases); G2 (0.4 ml i.p.); and PC + G2 (receiving both PC and G) adjuvants (twice a week for 4 weeks for all groups). Sensitization of animals was done by injection and inhalation of ovalbumin (OA).

Results:

All pathological changes in S group including the eosinophil infiltration (scoring 3.28 ± 0.28), lymphocyte infiltration (2.82 ± 0.26), local epithelial necrosis (2.71 ± 0.47) and mucosal plug (2.75 ± 0.37) were significantly higher than control group (0.64 ± 0.18, 1.36 ± 0.24, 0.36 ± 0.18 and 0.28 ± 0.18 for eosinophil infiltration, lymphocyte infiltration, epithelial necrosis and mucosal plug respectively, P < 0.001 for all cases). Treatment with all adjuvants improved all pathological changes significantly (P < 0.05 to P < 0.001).

Conclusions:

These results indicate preventive effects of all natural adjuvants (especially G2) on pathological changes of the lung in sensitized guinea pigs.

The impact of Zataria multiflora Boiss extract on in vitro and in vivo Th1/Th2 cytokine (IFN-γ/IL4) balance

ETHNOPHARMACOLOGICAL RELEVANCE

Anti-inflammatory, anti-oxidant and effect of Zataria multiflora on Th1/Th2 balance were previously described. Different therapeutic effects of this plant have been described in Iranian traditional medicine. To evaluate the immune modulatory effects of Zataria multiflora on Th1/Th2 balance, which may be implicated in inflammatory disorders, in vitro and in vivo studies were carried out.

MATERIALS AND METHODS

The effects of three concentrations of the extract, dexamethasone, and saline on interleukin 4 (IL-4) and interferon γ (IFN-γ) gene expression were evaluated in phytohemagglutinin (PHA) stimulated and non-stimulated human peripheral blood mononuclear cells (hPBMCs). RNA was extracted from the hPBMCs to make cDNA for real time PCR relative quantification. Furthermore, the effect of the extract on serum level of IL-4 and IFN-γ was assessed in ovalbumin (OA) sensitized guinea pigs (n=6 for each group).

RESULTS

Dexamethasone showed significant inhibitory effect on both IFN-γ and IL-4 gene expression and serum level of the cytokines and significantly enhanced IFN-γ/IL-4 ratio (p<0.05-p<0.001). The extract inhibited IL-4 and enhance IFN-γ gene expression and IFN-γ/IL-4 ratio too (p<0.05-p<0.001). In sensitized animals also serum level of IL-4 were significantly decreased after treatment with both dexamethasone and extract, but serum level of IFN-γ and IFN-γ/IL-4 ratio were significantly increased due to extract treatment (p<0.01 for medium and p<0.001 for high concentration).

CONCLUSIONS

These results indicated consistent in vitro and in vivo data for selective immune modulatory effect of the extract of Zataria multiflora which increased IFN-γ, decreased IL-4, and enhanced the ratio of IFN-γ to IL-4 (Th1/Th2 balance). Therefore, the extract of Zataria multiflora may have therapeutic value in inflammatory responses such as allergy, autoimmunity and infectious diseases associated with Th1/Th2 imbalance.

The effect of lead exposure on tracheal responsiveness to methacholine and ovalbumin, total and differential white blood cells count, and serum levels of immunoglobulin E, histamine, and cytokines in guinea pigs

The effect of exposure to inhaled lead acetate in guinea pigs was evaluated. The present study comprised of five groups of guinea pigs including control (C), sensitized to ovalbumin (OA; S) and three groups exposed to 0.1, 0.2, and 0.4 M inhaled lead (Pb; n = 6 for each group). Tracheal responsiveness to methacholine and OA, total and differential white blood cells (WBCs) count in lung lavage, serum levels of cytokines (interferon γ (IFN-γ) and interleukin 4 (IL-4)), histamines, and immunoglobulin E (IgE), and Pb concentration in lung were measured. Tracheal responsiveness to methacholine, OA, total and differential WBC types as well as IL-4, IFN-γ, histamine, and IgE were significantly increased but IFN-γ/IL-4 were significantly decreased in sensitized animals as well as those exposed to high Pb concentrations when compared with the control group (from p < 0.05 to p < 0.001). In addition, there was not a significant difference in most measured values between animals exposed to high Pb concentration and group S. The Pb concentration in lung tissues of animals exposed to all three Pb concentrations was significantly higher than that of group C (p < 0.001 for all cases).These results showed that inhaled lead acetate exposure can induce lung inflammatory changes similar to sensitized animals. Therefore, exposure to environmental Pb pollution may cause asthma-like changes.

Effect of carvacrol on tracheal responsiveness, inflammatory mediators, total and differential WBC count in blood of sensitized guinea pigs

The effects of carvacrol on tracheal responsiveness (TR) to methacholine and ovalbumin (OA), serum nitric oxide (NO) concentration, total and differential white blood cells (WBC) in blood of sensitized guinea pigs were examined. Five groups of guinea pigs sensitized to OA were given drinking water alone (group S), drinking water containing three concentrations of carvacrol (40, 80 and 160 μg/mL) and dexamethasone (50 μg/mL). TR to methacholine and OA, serum NO concentration, total and differential WBC in blood of sensitized and control guinea pigs were measured ( n = 6, for each group). TR to methacholine and OA, serum level of NO and nitrite, total WBC, eosinophil and neutrophil counts were increased but lymphocyte decreased in group S compared with control group ( P < 0.01 for NO and nitrite and P < 0.001 for other cases). Treatment of S animals with dexamethasone and two higher concentrations of carvacrol significantly improved all measured parameters except TR to OA in treated group with dexamethasone ( P < 0.05 to P < 0.001). Treatment of S animals with low concentration of carvacrol also improved TR to methacholine and OA, total WBC count and nitrite level ( P < 0.05 to P < 0.001). The effects of two higher concentrations of carvacrol on TR, NO and nitrite and the effects of its highest concentration on total and differential WBC count were significantly higher than those of dexamethasone ( P < 0.05 to P < 0.001). In addition, the effects of highest concentration of carvacrol on all parameters and its medium concentration on some parameters were significantly higher than its low concentration ( P < 0.05 to P < 0.001). These results showed a preventive effect of carvacrol on tracheal responsiveness, serum level of NO and nitrite, total and differential WBC in the blood of sensitized guinea pigs which was equal or even more potent than dexamethasone at used concentrations.

Potential immunomodulation effect of the extract of Nigella sativa on ovalbumin sensitized guinea pigs

Several different pharmacological effects have been described for Nigella sativa (Siah-Daneh), including an anti-inflammatory effect. In the present study, the effect of the extract of N. sativa on lung pathology and blood interleukin-4 (IL-4) and interferon-γ (IFN-γ) of sensitized guinea pigs was examined. Three groups (n=8 for each group) of guinea pigs sensitized to ovalbumin (OA) were given drinking water alone, and drinking water containing low and high concentrations of the plant extract, respectively. The animals of the control group (n=8) were treated with saline instead of OA and were given drinking water. The pathological changes of the lung, including infiltration of eosinophils and lymphocytes, local epithelial necrosis, the presence of oedema, thickening of the basement membrane, smooth muscle layer hypertrophy, mucosal secretion, and the presence of mucosal plug, and blood IL-4 and IFN-γ of sensitized guinea pigs were evaluated. The lungs of the sensitized group showed significant pathological changes (P<0.001). Blood IL-4 and IFN-γ were increased in sensitized animals compared to the controls (P<0.01 and P<0.001, respectively). Treatment of sensitized animals with the extract led to a significant decrease in pathological changes of the lung (P<0.01 to P<0.001), except for the oedema in the sensitized group treated with low concentration of the extract, but an increased IFN-γ. These results confirm a preventive effect of N. sativa extract on lung inflammation of sensitized guinea pigs.

The effect of natural adjuvants on tracheal responsiveness and cell count in lung lavage of sensitized guinea pigs

BACKGROUND AND OBJECTIVE

Airway inflammation is a well-characterized pathological feature of asthma. The effects of two natural adjuvants on lungs of sensitized guinea pigs were examined.

METHODS

The responses of guinea pig tracheal chains, WBC, differential WBC in lung lavage and IL-4 and interferon (IFN)-gamma levels in serum were examined in control guinea pigs and four treatment groups, including sensitized animals (S) and sensitized animals treated with the adjuvants PC (S + PC), G2 (S + G2) or both adjuvants (S + PCG2) (n = 6). Animals were sensitized by injection and inhalation of ovalbumin.

RESULTS

Tracheal responsiveness to methacholine (concentration of methacholine causing 50% of maximum contraction), WBC, eosinophil, neutrophil and basophil numbers were increased and lymphocyte numbers were decreased in lung lavage of sensitized animals compared with the control group (P < 0.01 to P < 0.001). However, G2 adjuvant and the combination of G2 and PC adjuvants caused a significant reduction in tracheal responsiveness (P < 0.01 and P < 0.001, respectively). In addition both adjuvants prevented changes in WBC (P < 0.001 for both). Both adjuvants and the combination prevented changes in eosinophil, neutrophil and basophil numbers in lung lavage of sensitized animals (P < 0.05 to P < 0.001). The adjuvants also prevented changes in IL-4 but increased IFN-gamma levels in all treatment groups compared with group S (P < 0.001 for all cases).

CONCLUSIONS

These results indicate that the two natural adjuvants (especially G2 adjuvant) and their combination have therapeutic effects, with reduction in tracheal responsiveness and WBC in lung lavage of sensitized guinea pigs.

Effects of oral alpha-tocopherol on lung response in rat model of allergic asthma

OBJECTIVE AND BACKGROUND

Asthma is a chronic inflammatory disease in which an oxidant/antioxidant imbalance plays an important role. d-alpha-tocopherol (biologically the most active form of vitamin E) has redox properties and by scavenging the free radicals can act as an antioxidant. The aim of this study was to examine the effects of orally administered alpha-tocopherol in a rat model of allergic asthma.

METHODOLOGY

Actively sensitized rats (OA) were treated with alpha-tocopherol (400 mg/kg/day for 10 days) or vehicle; 1 h after the last dose, they were challenged with antigen aerosol. The antigen-induced airway hyperresponsiveness to direct bronchoconstrictor (serotonin), the inflammatory cell infiltrate and histological changes were determined 1 or 24 h after the antigen challenge.

RESULTS

Alpha-tocopherol pretreatment was not significantly effective at reducing the studied parameters when compared with controls, even though there was a tendency to a reduction in bronchial responsiveness and in eosinophil and neutrophil infiltration.

CONCLUSION

Alpha-tocopherol when administered in the chosen study design in an animal model of asthma had no major effect on airway inflammation. The effect of antioxidants deserves further evaluation.

Relaxant effects of Rosa damascena on guinea pig tracheal chains and its possible mechanism(s)

Several therapeutic effects including hypnotic, antispasmodic, treatment of abdominal and chest pain and strengthening the heart have been described for the flowers of Rosa damascena. Therefore in the present study, the relaxant effects of ethanolic extract and essential oils of Rosa damascena on tracheal chains of guinea pigs were examined. The relaxant effects of four cumulative concentrations of ethanolic extract (0.25, 0.5, 0.75, and 1.0g%) and essential oils (0.25, 0.5, 0.75, and 1.0vol.%) in comparison with saline as negative control and four cumulative concentrations of theophylline (0.25, 0.5, 0.75, and 1.0mM) were examined by their relaxant effects on precontracted tracheal chains of guinea pig by 60mM KCl (group 1, n=5) and 10microM methacholine in two different conditions including: non-incubated tissues (group 2, n=8) and incubated tissues with 1microM propranolol and 1microM chlorpheniramine (group 3, n=5). In group 1 experiments two final concentrations of essential oil and theophylline and only final concentration of ethanolic extract showed relaxant effects compared to that of saline (p<0.01-0.001). In group 2 three higher concentrations of ethanolic extract and theophylline and all concentrations of essential oil showed concentration dependent relaxant effects compared to that of saline (p<0.05-0.001). In addition, the effect of 0.25 and 0.5g% of essential oils in group 2 was significantly higher than those of theophylline and ethanolic extract (p<0.01 for all cases). However, in group 3 experiments the extract and essential oil of Rosa damascena did not show any significant relaxant effect. There were significant correlations between the relaxant effects and concentrations for ethanolic extract and essential oil and theophylline in groups 1 and 2. These results showed a potent relaxant effect of Rosa damascena on tracheal chains of guinea pigs that was comparable to that of theophylline at concentrations used.