Treatment with pyranopyran-1, 8-dione attenuates airway responses in cockroach allergen sensitized asthma in mice

Phytochemicals as treatment for allergic asthma: Therapeutic effects and mechanisms of action

BACKGROUND

Allergic asthma is an inflammatory disease caused by the immune system's reaction to allergens, inflammation and narrowing of the airways, and the production of more than normal mucus. One of the main reasons is an increased production of inflammatory cytokines in the lungs that leads to the appearance of symptoms of asthma, including inflammation and shortness of breath. On the other hand, it has been proven that phytochemicals with their antioxidant and anti-inflammatory properties can be useful in improving allergic asthma.

PURPOSE

Common chemical treatments for allergic asthma include corticosteroids, which have many side effects and temporarily relieve symptoms but are not a cure. Therefore, taking the help of natural compounds to improve the quality of life of asthmatic patients can be a valuable issue that has been evaluated in the present review.

STUDY DESIGN AND METHODS

In this study, three databases (Scopus, PubMed, and Cochrane) with the keywords: allergic asthma, phytochemical, plant, and herb were evaluated. The primary result was 5307 articles. Non-English, repetitive, and review articles were deleted from the study.

RESULTS AND DISCUSSION

Finally, after carefully reading the articles, 102 were included in the study (2006-2022). The results of this review state that phytochemicals suppress the inflammatory pathways via inhibition of inflammatory cytokines production/secretion, genes, and proteins involved in the inflammation process, reducing oxidative stress indicators and symptoms of allergic asthma, such as cough and mucus production in the lungs.

CONCLUSION

With their antioxidant effects, this study concluded that phytochemicals suppress cytokines and other inflammatory indicators and thus can be considered an adjunctive treatment for improving allergic asthma.

Comprehensive identification of Vitex trifolia fruit and its five adulterants by comparison of micromorphological, microscopic characteristics, and chemical profiles

Prevention against the adulteration of traditional Chinese medicine in an accurate way has been long exploring. Vitex trifolia fruit (VTF), as a widely used analgesic in East Asia, has frequently been found to be adulterated with five adulterants, namely Vitex cannabifolia fruit (VCF) (Fam. Verbenaceae), Vitex negundo fruit (VNF) (Fam. Verbenaceae), Piper cubeba fruit (PCF) (Fam. Lauraceae), Euphorbia lathyris seed (ELS) (Fam. Euphorbiaceae), and Vaccinium bracteatum fruit (VBF) (Fam. Ericaceae). In this study, the methods of micromorphological identification, microscopic identification, and chemical analysis were combined to distinguish VTF from its five adulterants comprehensively. As a result, the micromorphological features in terms of fruit or seed epidermis were photographed by stereomicroscopy firstly. Secondly, the microscopic characteristics of various herb powders were captured under light microscopy. Thirdly, 33 nonvolatile components and 124 volatile components in VTF were identified by ultra-performance liquid chromatography coupled with Orbitrap mass spectrometry (UPLC-Orbitrap-MS) and comprehensive two-dimensional gas chromatography hyphenated with mass spectrometry (GC × GC-MS), respectively. Furthermore, betulinic acid, persicogenin, and the volatile 4-(2,2,6-trimethyl-bicyclo[4.1.0]hept-1-yl)-butan-2-one were screened out to be the specific markers of VTF distinctive from the adulterants. Collectively, VTF and its five adulterants were distinguished successfully by the comparison of micromorphological, microscopic characteristics, and chemical profiles.

Use of Natural Products in Asthma Treatment

Asthma, a disease classified as a chronic inflammatory disorder induced by airway inflammation, is triggered by a genetic predisposition or antigen sensitization. Drugs currently used as therapies present disadvantages such as high cost and side effects, which compromise the treatment compliance. Alternatively, traditional medicine has reported the use of natural products as alternative or complementary treatment. The aim of this review was to summarize the knowledge reported in the literature about the use of natural products for asthma treatment. The search strategy included scientific studies published between January 2006 and December 2017, using the keywords "asthma," "treatment," and "natural products." The inclusion criteria were as follows: (i) studies that aimed at elucidating the antiasthmatic activity of natural-based compounds or extracts using laboratory experiments (in vitro and/or in vivo); and (ii) studies that suggested the use of natural products in asthma treatment by elucidation of its chemical composition. Studies that (i) did not report experimental data and (ii) manuscripts in languages other than English were excluded. Based on the findings from the literature search, aspects related to asthma physiopathology, epidemiology, and conventional treatment were discussed. Then, several studies reporting the effectiveness of natural products in the asthma treatment were presented, highlighting plants as the main source. Moreover, natural products from animals and microorganisms were also discussed and their high potential in the antiasthmatic therapy was emphasized. This review highlighted the importance of natural products as an alternative and/or complementary treatment source for asthma treatment, since they present reduced side effects and comparable effectiveness as the drugs currently used on treatment protocols.

Advanced Molecular Knowledge of Therapeutic Drugs and Natural Products Focusing on Inflammatory Cytokines in Asthma

Asthma is a common respiratory disease worldwide. Cytokines play a crucial role in the immune system and the inflammatory response to asthma. Abnormal cytokine expression may lead to the development of asthma, which may contribute to pathologies of this disease. As cytokines exhibit pleiotropy and redundancy characteristics, we summarized them according to their biologic activity in asthma development. We classified cytokines in three stages as follows: Group 1 cytokines for the epithelial environment stage, Group 2 cytokines for the Th2 polarization stage, and Group 3 cytokines for the tissue damage stage. The recent cytokine-targeting therapy for clinical use (anti-cytokine antibody/anti-cytokine receptor antibody) and traditional medicinal herbs (pure compounds, single herb, or natural formula) have been discussed in this review. Studies of the Group 2 anti-cytokine/anti-cytokine receptor therapies are more prominent than the studies of the other two groups. Anti-cytokine antibodies/anti-cytokine receptor antibodies for clinical use can be applied for patients who did not respond to standard treatments. For traditional medicinal herbs, anti-asthmatic bioactive compounds derived from medicinal herbs can be divided into five classes: alkaloids, flavonoids, glycosides, polyphenols, and terpenoids. However, the exact pathways targeted by these natural compounds need to be clarified. Using relevant knowledge to develop more comprehensive strategies may provide appropriate treatment for patients with asthma in the future.

Immune Homeostasis: Effects of Chinese Herbal Formulae and Herb-Derived Compounds on Allergic Asthma in Different Experimental Models

Allergic asthma is thought to arise from an imbalance of immune regulation, which is characterized by the production of large quantities of IgE antibodies by B cells and a decrease of the interferon-γ/interleukin-4 (Th1/Th2) ratio. Certain immunomodulatory components and Chinese herbal formulae have been used in traditional herbal medicine for thousands of years. However, there are few studies performing evidence-based Chinese medicine (CM) research on the mechanisms and effificacy of these drugs in allergic asthma. This review aims to explore the roles of Chinese herbal formulae and herb-derived compounds in experimental research models of allergic asthma. We screened published modern CM research results on the experimental effects of Chinese herbal formulae and herb-derived bioactive compounds for allergic asthma and their possible underlying mechanisms in English language articles from the PubMed and the Google Scholar databases with the keywords allergic asthma, experimental model and Chinese herbal medicine. We found 22 Chinese herb species and 31 herb-derived anti-asthmatic compounds as well as 12 Chinese herbal formulae which showed a reduction of airway hyperresponsiveness, allergen-specifific immunoglobulin E, inflflammatory cell infifiltration and a regulation of Th1 and Th2 cytokines in vivo, in vitro and ex vivo, respectively. Chinese herbal formulae and herbderived bioactive compounds exhibit immunomodulatory, anti-inflflammatory and anti-asthma activities in different experimental models and their various mechanisms of action are being investigated in modern CM research with genomics, proteomics and metabolomics technologies, which will lead to a new era in the development of new drug discovery for allergic asthma in CM.

Targeted inhibition of Six1 attenuates allergic airway inflammation and remodeling in asthmatic mice

Asthma is an inflammatory disease of the airways, characterized by lung eosinophilia, mucus hypersecretion by goblet cells and airway hyperresponsiveness to inhaled allergens. The purpose of this study was to evaluate the effects of Six1 on airway inflammation and remodeling and the underlying mechanisms in a murine model of chronic asthma. Female BALB/c mice were randomly divided into four groups: phosphate-buffered saline control, ovalbumin (OVA)-induced asthma group, OVA+siNC and OVA+siSix1. In this mice model, Six1 expression level was significantly elevated in OVA-induced asthma of mice. Additionally, downregulation of Six1 dramatically decreased OVA-challenged inflammation, infiltration, and mucus production. Moreover, silencing of Six1 resulted in decreased levels of immunoglobulin E and inflammatory mediators and reduced inflammatory cell accumulation, as well as inhibiting the expression of important mediators including matrix metalloproteinase MMP-2 and MMP-9, which is related to airway remodeling. Further analysis indicated that silencing of Six1 can significantly inhibit NF-kB pathway activation in the lungs. .In conclusion, these findings indicated that the downregulation of Six1 effectively inhibited airway inflammation and reversed airway remodeling, which suggest that Six1 represents a promising therapeutic strategy for human allergic asthma.

Proteinase activated receptor-2-mediated dual oxidase-2 up-regulation is involved in enhanced airway reactivity and inflammation in a mouse model of allergic asthma

Airway epithelial cells (AECs) express a variety of receptors, which sense danger signals from various aeroallergens/pathogens being inhaled constantly. Proteinase-activated receptor 2 (PAR-2) is one such receptor and is activated by cockroach allergens, which have intrinsic serine proteinase activity. Recently, dual oxidases (DUOX), especially DUOX-2, have been shown to be involved in airway inflammation in response to Toll-like receptor activation. However, the association between PAR-2 and DUOX-2 has not been explored in airways of allergic mice. Therefore, this study investigated the contribution of DUOX-2/reactive oxygen species (ROS) signalling in airway reactivity and inflammation after PAR-2 activation. Mice were sensitized intraperitoneally with intact cockroach allergen extract (CE) in the presence of aluminium hydroxide followed by intranasal challenge with CE. Mice were then assessed for airway reactivity, inflammation, oxidative stress (DUOX-2, ROS, inducible nitric oxide synthase, nitrite, nitrotyrosine and protein carbonyls) and apoptosis (Bax, Bcl-2, caspase-3). Challenge with CE led to up-regulation of DUOX-2 and ROS in AECs with concomitant increases in airway reactivity/inflammation and parameters of oxidative stress, and apoptosis. All of these changes were significantly inhibited by intranasal administration of ENMD-1068, a small molecule antagonist of PAR-2 in allergic mice. Administration of diphenyliodonium to allergic mice also led to improvement of allergic airway responses via inhibition of the DUOX-2/ROS pathway; however, these effects were less pronounced than PAR-2 antagonism. The current study suggests that PAR-2 activation leads to up-regulation of the DUOX-2/ROS pathway in AECs, which is involved in regulation of airway reactivity and inflammation via oxidative stress and apoptosis.

The asymmetric hetero-Diels-Alder reaction in the syntheses of biologically relevant compounds

The hetero-Diels-Alder reaction is one of the most powerful transformations in the chemistry toolbox for the synthesis of aza- and oxa-heterocycles embodying multiple stereogenic centers. However, as compared to other cycloadditions, in particular the dipolar cycloadditions and the Diels-Alder reaction, the hetero-Diels-Alder reaction has been much less explored and exploited in organic synthesis. Nevertheless, this powerful transformation has opened up efficient and creative routes to biologically relevant small molecules and different natural products which contain six-membered oxygen or nitrogen ring systems. Recent developments in this field, in particular in the establishment of enantioselectively catalyzed hetero-Diels-Alder cycloadditions steered by a plethora of different catalysts and the application of the resulting small molecules in chemical biology and medicinal chemistry research, are highlighted in this Minireview.