Flavonoids in the therapy and prophylaxis of flu: a patent review

Western Dietary Pattern Antioxidant Intakes and Oxidative Stress: Importance During the SARS-CoV-2/COVID-19 Pandemic

The importance of balanced dietary habits, which include appropriate amounts of antioxidants to maintain the immune system, has become increasingly relevant during the current SARS-CoV-2/COVID-19 pandemic, because viral infections are characterized by high oxidative stress. Furthermore, the measures taken by governments to control the pandemic have led to increased anxiety, stress, and depression, which affect physical and mental health, all of which are influenced by nutritional status, diet, and lifestyle. The Mediterranean diet (MD), Atlantic diet (AD), and the Dietary Guidelines for Americans all provide the essential vitamins, minerals, and phenolic compounds needed to activate enzymatic and nonenzymatic antioxidant responses. However, viral pandemics such as the current COVID-19 crisis entail high oxidative damage caused by both the infection and the resultant social stresses within populations, which increases the probability and severity of infection. Balanced dietary patterns such as the MD and the AD are characterized by the consumption of fruit, vegetables, legumes, olive oil, and whole grains with low intakes of processed foods and red meat. For a healthy lifestyle in young adults, the MD in particular provides the required amount of antioxidants per day for vitamins D (0.3-3.8 μg), E (17.0 mg), C (137.2-269.8 mg), A (1273.3 μg), B-12 (1.5-2.0 μg), and folate (455.1-561.3 μg), the minerals Se (120.0 μg), Zn (11.0 mg), Fe (15.0-18.8 mg), and Mn (5.2-12.5 mg), and polyphenols (1171.00 mg) needed to maintain an active immune response. However, all of these diets are deficient in the recommended amount of vitamin D (20 μg/d). Therefore, vulnerable populations such as elders and obese individuals could benefit from antioxidant supplementation to improve their antioxidant response. Although evidence remains scarce, there is some indication that a healthy diet, along with supplemental antioxidant intake, is beneficial to COVID-19 patients.

Synthesis and biological evaluation of 6-nitro-1,2,4-triazoloazines containing polyphenol fragments possessing antioxidant and antiviral activity

Stable σ-adducts of azolo[5,1-c]triazines and azolo[1,5-a]pyrimidines with different polyphenols were synthesized and their antioxidant and antiviral activity were investigated. Their affinity to viral hemagglutinin was assessed using molecular modelling. The phloroglucinol-modified azolo-azines possessed the highest virus-inhibiting activity. According to the results of the study of antioxidant properties of compounds, the most promising ones exhibiting highest antioxidant capacity were adducts containing in their structure pyrogallol and catechol residues and 6-nitro-triazolotriazin-7-ol scaffold. No correlation between antioxidant and virus-inhibiting activity of compounds studied was detected. The most active compounds demonstrated the ability to prevent binding of viral hemagglutinin with cellular receptor as shown in hemagglutination inhibition assay. Our results demonstrate that polyphenol-modified azolo-azines are prospective for further optimization as potential antivirals and that their action is directed against viral hemagglutinin.

Discovery of prenylated flavonoids with dual activity against influenza virus and Streptococcus pneumoniae

Influenza virus neuraminidase (NA) is the primary target for influenza therapeutics. Severe complications are often related to secondary pneumonia caused by Streptococcus pneumoniae (pneumococci), which also express NAs. Recently, a NA-mediated lethal synergism between influenza A viruses and pneumococci was described. Therefore, dual inhibitors of both viral and bacterial NAs are expected to be advantageous for the treatment of influenza. We investigated the traditional Chinese herbal drug sāng bái pí (mulberry root bark) as source for anti-infectives. Two prenylated flavonoid derivatives, sanggenon G (4) and sanggenol A (5) inhibited influenza A viral and pneumococcal NAs and, in contrast to the approved NA inhibitor oseltamivir, also planktonic growth and biofilm formation of pneumococci. Evaluation of 27 congeners of 5 revealed a correlation between the degree of prenylation and bioactivity. Abyssinone-V 4′-methyl ether (27) inhibited pneumococcal NA with IC₅₀ = 2.18 μM, pneumococcal growth with MIC = 5.63 μM, and biofilm formation with MBIC = 4.21 μM, without harming lung epithelial cells. Compounds 5 and 27 also disrupt the synergism between influenza A virus and pneumococcal NA in vitro, hence functioning as dual-acting anti-infectives. The results warrant further studies on whether the observed disruption of this synergism is transferable to in vivo systems.

2',4'-dihydroxychalcone, a flavonoid isolated from Herba oxytropis, suppresses PC-3 human prostate cancer cell growth by induction of apoptosis

Natural products are a promising source for the development of novel cancer therapies, due to their potential effectiveness and low toxicity profiles. As a main component of Herba oxytropis, 2',4'-dihydroxychalcone (TFC) is known to demonstrate anti-tumor activity in vitro. In the present study, TFC was found to potently inhibit proliferation and induce apoptosis in PC-3 human prostate cancer cells in a dose-dependent manner. The results demonstrated that the induction of apoptosis is associated with cell cycle arrest at the G0/G1 phase and activation of caspase-3/-7. Additional mechanistic studies of two biomarkers, phosphatase and tensin homolog (PTEN) and cyclin-dependent kinase inhibitor 1B (p27^Kip1), in prostate cancer revealed that TFC treatment significantly upregulated the expression of PTEN and p27^Kip1. The findings of the present study indicate that TFC-induced apoptosis in PC-3 cells via upregulation of PTEN and p27^Kip1, which results in cell cycle arrest in G0/G1 phase, activation of caspase-3/-7 and induction of apoptosis. Therefore, TFC may be a potential compound for human prostate cancer therapy.

Flavonoid apigenin inhibits lipopolysaccharide-induced inflammatory response through multiple mechanisms in macrophages

Background

Apigenin is a non-toxic natural flavonoid that is abundantly present in common fruits and vegetables. It has been reported that apigenin has various beneficial health effects such as anti-inflammation and chemoprevention. Multiple studies have shown that inflammation is an important risk factor for atherosclerosis, diabetes, sepsis, various liver diseases, and other metabolic diseases. Although it has been long realized that apigenin has anti-inflammatory activities, the underlying functional mechanisms are still not fully understood.

Methodology and Principal Findings

In the present study, we examined the effect of apigenin on LPS-induced inflammatory response and further elucidated the potential underlying mechanisms in human THP-1-induced macrophages and mouse J774A.1 macrophages. By using the PrimePCR array, we were able to identify the major target genes regulated by apigenin in LPS-mediated immune response. The results indicated that apigenin significantly inhibited LPS-induced production of pro-inflammatory cytokines, such as IL-6, IL-1β, and TNF-α through modulating multiple intracellular signaling pathways in macrophages. Apigenin inhibited LPS-induced IL-1β production by inhibiting caspase-1 activation through the disruption of the NLRP3 inflammasome assembly. Apigenin also prevented LPS-induced IL-6 and IL-1β production by reducing the mRNA stability via inhibiting ERK1/2 activation. In addition, apigenin significantly inhibited TNF-α and IL-1β-induced activation of NF-κB.

Conclusion and Significance

Apigenin Inhibits LPS-induced Inflammatory Response through multiple mechanisms in macrophages. These results provided important scientific evidences for the potential application of apigenin as a therapeutic agent for inflammatory diseases.

Ultrasound-assisted extraction of total flavonoids from Aconitum gymnandrum

BACKGROUND

Aconitum gymnandrum is a Chinese traditional herb used as carminative and analgesic. In this study, A. gymnandrum was used as an experimental matrix.

MATERIALS AND METHODS

Optimized ultrasonic extraction technology of total flavonoids from the A. gymnandrum Maxim was studied by using the methodology of single factor and orthogonal design to study the effects of operation conditions, such as ethanol content, ultrasonic wave power, temperature, ultrasonic wave radiation time, and the ratio of sample weight to solvent volume.

RESULT

THROUGH THE ORTHOGONAL EXPERIMENT, THE OPTIMAL EXTRACTION CONDITIONS WERE DETERMINED AS FOLLOWS: Ultrasonic power 100 W, ultrasonic temperature 45°C, 60% ethyl alcohol, extraction time 30 min, and solid-liquid ratio 1:20.

CONCLUSION

Under the optimum parameters, the extraction ratio of total flavonoids from the A. gymnandrum Maxim is about 1.278%.

Antiviral activity of Ladania067, an extract from wild black currant leaves against influenza A virus in vitro and in vivo

Influenza, a respiratory disease caused by influenza viruses, still represents a major threat to humans and several animal species. Besides vaccination, only two classes of drugs are available for antiviral treatment against this pathogen. Thus, there is a strong need for new effective antivirals against influenza viruses. Here, we tested Ladania067, an extract from the leaves of the wild black currant (Ribes nigrum folium) for potential antiviral activity against influenza A virus in vitro and in vivo. In the range of 0-1 mg/ml the extract showed no cytotoxic effect on three cell lines and a CC50 of 0.5 ± 0.3 mg/ml, on peripheral blood mononuclear cells. Furthermore, the extract did not influence the proliferative status of human lymphocytes. In contrast, Ladania067 was highly effective (EC50 value: 49.3 ± 1.1 ng/ml) against the human pandemic influenza virus strain A/Regensburg/D6/09 (H1N1). The extract exhibited an antiviral effect when the virus was pre-incubated prior to infection or when added directly after infection. No antiviral effect was found when infected cells were treated 2, 4, or 8 h after infection, indicating that Ladania067 blocks a very early step in the virus infection cycle. In the mouse infection model we were able to demonstrate that an intranasal application of 500 μg Ladania067 inhibits progeny virus titers in the lung up to 85% after 24 h. We conclude that the extract from the leaves of the wild black currant may be a promising source for the identification of new molecules with antiviral functions against influenza virus.

Prevention and Control of Influenza Viruses

The 2003–2004 outbreaks of highly pathogenic avian influenza (HPAI) have proven to be disastrous to the regional poultry industry in Asia, and have raised serious worldwide public health apprehension regarding the steps that should be taken to urgently control HPAI. Control measures must be taken based on the principles of biosecurity and disease management and at the same time making public aware of the precautionary measures at the verge of outbreak. Creation of protection and surveillance zones, various vaccination strategies viz. routine, preventive, emergency, mass and targeted vaccination programmes using live, inactivated and recombinant vaccines are the common strategies adopted in different parts of the globe. The new generation vaccines include recombinant vaccines and recombinant fusion vaccine. The pro-poor disease control programmes, giving compensation and subsidies to the farmers along with effective and efficient Veterinary Services forms integral part of control of HPAI. Following biosecurity principles and vaccination forms integral part of control programme against swine and equine influenza as well. Use of neuraminidase (NA) inhibitors (Zanamivir and Oseltamivir) for the treatment of human influenza has been widely accepted worldwide. The threat of increasing resistance of the flu viruses to these antivirals has evoked interest in the development of novel antiviral drugs for influenza virus such as inhibitors of cellular factors and host signalling cascades, cellular miRNAs, siRNA and innate immune peptides (defensins and cathelicidins). Commercial licensed inactivated vaccines for humans against influenza A and B viruses are available consisting of three influenza viruses: influenza type A subtype H3N2, influenza type A subtype H1N1 (seasonal) virus strain and influenza type B virus strain. As per WHO, use of tetravaccine consisting of antigens of influenza virus serotypes H3N2, H1N1, B and H5 is the most promising method to control influenza pandemic. All healthy children in many countries are required to be vaccinated between 6 and 59 months of age. The seasonal vaccines currently used in humans induce strain-specific humoral immunity as the antibodies. Universal influenza virus vaccines containing the relatively conserved ectodomain of M2 (M2e), M1, HA fusion peptide and stalk domains, NA, NP alone or in combination have been developed which have been shown to induce cross-protection. The T cell-based vaccines are another recent experimental approach that has been shown to elicit broad-spectrum heterosubtypic immunity in the host. As far as HPAI is concerned, various pandemic preparedness strategies have been documented.