Potent suppressive effects of 3-O-methylquercetin 5,7,3',4'-O-tetraacetate on ovalbumin-induced airway hyperresponsiveness

RP-HPLC Estimation of Flavonol Derivatives and Phenolic Acids in Capsicum annuum L. and their Correlation with In Vitro Anti-Inflammatory Activity

BACKGROUND

Flavonol derivative and phenolic acids derived from the plants function as free radical scavengers, reducing agents, and quenchers for the formation of singlet oxygen. Flavonoids and phenolic constituents also play an important role in various human diseases and disorders primarily through modulation of inflammatory responses.

OBJECTIVE

To estimate the Flavonol Derivatives (FD) and phenolic acids (PA) in Capsicum annuum (CA) and other important phytochemicals having an anti-inflammatory effect.

METHODS

In the present study, FD and PA were estimated in CA and in vitro anti-inflammatory activity (pilot study) was determined and correlation was established.

RESULTS

The results were found to be significant using RP-HPLC. FD and PA were found to be 0.0659±0.0058 and 0.0862±0.0.0134 mg/gram dry weight, respectively. For in vitro anti-inflammatory activity, the inhibition of albumin denaturation and antiproteinase activity was found to be maximum in Quercetin (QE) with 98.230±1.589% and 59.906±1.529%, respectively. Heat-induced hemolysis of erythrocytes was found to be maximum in salicylic acid (SA) (71.830±2.838%). Hypotonicity-induced hemolysis showed significant activity with QE (76.770±3.475%). Lipoxygenase and cyclooxygenase inhibition was found to be maximum in QE with 56.930±4.069% and 61.660±3.135%, respectively.

CONCLUSION

A strong positive correlation of 0.9 was observed between the extract of CA and standard QE and SA against the anti-inflammatory activity. Therefore, the role of FD and PA has been postulated to be an active phytochemical of CA accountable for its anti-inflammatory activity. However further work is desirable to fully elucidate the phytochemicals responsible for their anti-inflammatory activity and to develop better herbal drug formulations.

Establishment and characterization of an experimental mouse model of allergic rhinitis

Allergic rhinitis (AR) is a common worldwide disease. Animal studies on AR were adopted in various investigations. However, animal studies simply aimed at establishing an animal model for AR have been seldom seen. The purpose of this study was to introduce an easy-to-establish experimental mouse model of AR. To develop a mouse model of AR, 38 Balb/c mice were randomly assigned to two groups. Mice in the study group were sensitized by intraperitoneal (IP) injection of ovalbumin (OVA) on day 1 and 6, followed by continuous inhalation (IH) of OVA solution for 1 week (day 8-14) using a newly designed inhalation box. The control group mice received sensitization of IP normal saline and IH sterilized distilled water instead of OVA. Before and after sensitization, the frequencies of nasal symptoms (sneezing, nasal rubbing) were recorded and the serum levels of total immunoglobulin E (IgE) were evaluated using ELISA. Finally, the murine nasal mucosal tissues were stained by Giemsa solution to estimate the degree of mast cell infiltration. After sensitization by IP and IH OVA, the study group showed significant phenotypic changes including increased sneezing and rubbing. Pathological and cytological findings also confirmed significant elevated serum total IgE titer and local mast cell infiltration in the study group statistically. We successfully developed a workable experimental animal model for AR that was more easily sensitized using our new-designed inhalation box, with less stress and more precisely to be observed.

Flavonoids and asthma

Asthma is a chronic disease, characterized by airway inflammation, airflow limitation, hyper-reactivity and airway remodeling. It is believed that asthma is caused by the interaction between genetic and environmental factors. The prevalence of allergic diseases, including asthma, has increased worldwide during the past two decades. Although the precise reasons that have caused this increase remain unknown, dietary change is thought to be one of the environmental factors. Flavonoids, which are polyphenolic plant secondary metabolites ubiquitously present in vegetables, fruits and beverages, possess antioxidant and anti-allergic traits, as well as immune-modulating activities. Flavonoids are powerful antioxidants and anti-allergic nutrients that inhibit the release of chemical mediators, synthesis of Th2 type cytokines, such as interleukin (IL)-4 and IL-13, and CD40 ligand expression by high-affinity immunoglobulin E (IgE) receptor-expressing cells, such as mast cells and basophils. They also inhibit IL-4-induced signal transduction and affect the differentiation of naïve CD4+ T cells into effector T-cells through their inhibitory effect on the activation of the aryl hydrocarbon receptor. Various studies of flavonoids in asthmatic animal models have demonstrated their beneficial effects. The results of several epidemiological studies suggest that an increase in flavonoid intake is beneficial for asthma. Moreover, clinical trials of flavonoids have shown their ameliorative effects on symptoms related to asthma. However, these human studies are currently limited; further validation is required to clarify whether an appropriate intake of flavonoids may constitute dietary treatment and for part of a preventive strategy for asthma.

Quercetin: a flavonoid with the potential to treat asthma

Allergic asthma is a complex inflammatory disorder characterized by airway hyperresponsiveness, eosinophilic inflammation and hypersecretion of mucus. Current therapies include β2-agonists, cysteinyl leukotriene receptor 1 antagonists and corticosteroids. Although these drugs demonstrate beneficial effects, their adverse side effects limit their long-term use. Thus, the development of new compounds with similar therapeutic activities and reduced side effects is both desirable and necessary. Natural compounds are used in some current therapies, as plant-derived metabolites can relieve disease symptoms in the same manner as allopathic medicines. Quercetin is a flavonoid that is naturally found in many fruits and vegetables and has been shown to exert multiple biological effects in experimental models, including the reduction of major symptoms of asthma: bronchial hyperactivity, mucus production and airway inflammation. In this review, we discuss results from the literature that illustrate the potential of quercetin to treat asthma and its exacerbations.

Bioassay-guided fractionation of a thymol-deprived hydrophilic thyme extract and its antispasmodic effect

ETHNOPHARMACOLOGICAL RELEVANCE

Extracts from Thymus vulgaris L. and Thymus zygis L. are traditionally used for bronchitis, catarrhs of the respiratory tract and supportive treatment of pertussis. A potential spasmolytic effect is thought to be due to the presence of the monoterpenoid phenols thymol and carvacrol in the extract. Based on previous data the present investigation aimed to clarify if thymol-deprived thyme extracts (as been in use within German drug market) have antispasmodic activity. Additionally compounds responsible for this effect had to be identified.

MATERIALS AND METHODS

Thyme fluid extract was subsequently fractionated by FCPC, LPLC, and HPLC and compounds isolated were identified by spectroscopic methods. Bioassay testing was done by quantification of antispasmodic activity in the preconstricted rat smooth muscle trachea model against papaverin as positive control.

RESULTS

Thymol-deprived spissum extract (SE) had good antispasmodic activity (-37%, related to the maximum contraction). Bioassay-guided fractionation indicated that rosmarinic acid and apigenin do not contribute to this effect. Luteolin contributed significantly to the antispasmodic activity (-9%).

CONCLUSIONS

Thyme extracts have antispasmodic activity, which is at least due to synergistic effects of phenolic volatile oil compounds and the flavone luteolin. Specifications of thyme-containing preparations should refer to this flavone in addition to focusing on the volatile phenols.

Effects of flavonoids and other polyphenols on inflammation

Flavonoids are a family of polyphenolic compounds which are widespread in nature (vegetables) and are consumed as part of the human diet in significant amounts. There are other types of polyphenols, including, for example, tannins and resveratrol. Flavonoids and related polyphenolic compounds have significant antiinflammatory activity, among others. This short review summarizes the current knowledge on the effects of flavonoids and related polyphenolic compounds on inflammation, with a focus on structural requirements, the mechanisms involved, and pharmacokinetic considerations. Different molecular (cyclooxygenase, lipoxygenase) and cellular targets (macrophages, lymphocytes, epithelial cells, endothelium) have been identified. In addition, many flavonoids display significant antioxidant/radical scavenging properties. There is substantial structural variation in these compounds, which is bound to have an impact on their biological profile, and specifically on their effects on inflammatory conditions. However, in general terms there is substantial consistency in the effects of these compounds despite considerable structural variations. The mechanisms have been studied mainly in myeloid cells, where the predominant effect is an inhibition of NF-κB signaling and the downregulation of the expression of proinflammatory markers. At present there is a gap in knowledge of in vitro and in vivo effects, although the pharmacokinetics of flavonoids has advanced considerably in the last decade. Many flavonoids have been studied for their intestinal antiinflammatory activity which is only logical, since the gastrointestinal tract is naturally exposed to them. However, their potential therapeutic application in inflammation is not restricted to this organ and extends to other sites and conditions, including arthritis, asthma, encephalomyelitis, and atherosclerosis, among others.

Suppression of type-I allergic responses by oral administration of grape marc fermented with Lactobacillus plantarum

We investigated the inhibitory effects of fermented grape marc (FGM), lyophilized fine powder of skin, and seeds of Vitis vinifera Koshu grape prepared by fermentation with Lactobacillus plantarum, on type-I allergic responses in mice. Repeated oral administration of FGM, but not non-fermented grape marc (GM), to BALB/c mice primed with ovalbumin (OVA) resulted in a significant reduction of serum IgE levels, compared with those of immunized controls. After OVA challenge, increased numbers of eosinophils in bronchial alveolar lavage fluids (BALF) significantly decreased by treatment with FGM but not with GM. For passive cutaneous anaphylaxis (PCA) reaction, BALB/c mice received intradermal sensitization with anti-OVA IgE serum and were challenged intravenously with OVA containing Evans blue at 24 h after IgE sensitization. Oral administration of FGM at 30 min before OVA challenge significantly suppressed the PCA reaction. On the other hand, Lactobacillus alone and non-fermented GM did not show any suppressive effects. Interestingly, FGM samples prepared from grapes for red wine, such as Negroamaro (rich in resveratrol) or Tannat (rich in oligomeric procyanidin), did not suppress the reaction. These results indicate that oral administration of FGM, prepared from Koshu grape for white wine but not from grapes for red wine, could suppress both phases of type-I allergic responses. A fraction extractable with acetone was responsible for the suppressive effects of FGM.

Inhibitory effects of quercetin derivatives on phosphodiesterase isozymes and high-affinity [(3) H]-rolipram binding in guinea pig tissues

Rolipram has high (PDE4(H)) and low (PDE4(L)) affinities for phosphodiesterase (PDE)-4, respectively. In general, it is believed that inhibitions by PDE4(H) and PDE4(L) are respectively associated with an adverse response and with anti-inflammatory and bronchodilating effects. This has provided a rational basis for designing new compounds with high PDE4(H)/PDE4(L) ratios. In the present study, we attempted to determine the PDE4(H)/PDE4(L) ratios of quercetin (1), qercetin-3-O-methylether (3-MQ, 2), quercetin-3,7,4'-O-trimethylether (ayanin, 3), quercetin-3,7,3',4'-O- tetramethylether (QTME, 4), quercetin-3,5,7,3',4'-O-petamethylether (QPME, 5), quercetin-3,5,7,3',4'-O-pentaacetate (QPA, 6), and quercetin-3-O-methyl-5,7,3',4'-O-tetraacetate (QMTA, 7). The activities of PDE1 approximately 5, which were partially separated from homogenates of guinea pig lungs and hearts, were measured by a two-step procedure using adenosine 3',5'-cyclic monophosphate (cAMP) with [(3) H]-cAMP or guanosine 3',5'-cyclic monophosphate (cGMP) with [(3) H]-cGMP as substrates. The IC(50) values of all of these compounds except quercetin (1), 3-MQ (2), and QMTA (7) on PDE1 approximately 5 inhibition were determined. The anti-inflammatory effects of PDE4 inhibitors were reported to be associated with inhibition of PDE4 catalytic activity. Therefore, these IC(50) values for PDE4 inhibition were taken as the PDE4(L) values. The effective concentration (EC(50)), at which one half of the [(3) H]-rolipram bound to high-affinity rolipram binding sites (HARBSs) of brain cell membranes was replaced, was defined as the PDE4(H) value. In the present results, the PDE4(H)/PDE4(L) ratios of quercetin (1), ayanin (3), and QPME (5) were >30, >19, and 11, respectively (Table 1), which are higher than or equal to that of AWD12-281, the selective PDE4 inhibitor with the greatest potential currently undergoing clinical trials for treating asthma and chronic obstructive pulmonary disease.