Synergistic activity of baicalein with ribavirin against influenza A (H1N1) virus infections in cell culture and in mice

A comprehensive overview on antiviral effects of baicalein and its glucuronide derivative baicalin

Natural product-based antiviral candidates have received significant attention. However, there is a lack of sufficient research in the field of antivirals to effectively combat patterns of drug resistance. Baicalein and its glucuronide derivative baicalin are two main components extracted from Scutellaria baicalensis Georgi. They have proven to be effective against a broad range of viruses by directly killing virus particles, protecting infected cells, and targeting viral antigens on their surface, among other mechanisms. As natural products, they both possess the advantage of lower toxicity, enhanced therapeutic efficacy, and even antagonistic effects against drug-resistant viral strains. Baicalein and baicalin exhibit promising potential as potent pharmacophore scaffolds, demonstrating their antiviral properties. However, to date, no review on the antiviral effects of baicalein and baicalin has been published. This review summarizes the recent research progress on antiviral effects of baicalein and baicalin against various types of viruses both in vitro and in vivo with a focus on the dosages and underlying mechanisms. The aim is to provide a basis for the rational development and utilization of baicalein and baicalin, as well as to promote antiviral drug research. Please cite this article as: Liu XY, Xie W, Zhou HY, Zhang HQ, Jin YS. A comprehensive overview on antiviral effects of baicalein and its glucuronide derivative baicalin. J Integr Med. 2024; 22(6): 621-636.

A Cyclic Peptide Based on Pheasant Cathelicidin Inhibits Influenza A H1N1 Virus Infection

Influenza viruses are the leading cause of upper respiratory tract infections, leading to several global pandemics and threats to public health. Due to the continuous mutation of influenza A viruses, there is a constant need for the development of novel antiviral therapeutics. Recently, natural antimicrobial peptides have provided an opportunity for the discovery of anti-influenza molecules. Here, we designed several peptides based on pheasant cathelicidin and tested their antiviral activities and mechanisms against the H1N1 virus. Of note, the designed peptides Pc-4 and Pc-5 were found to inhibit replication of the H1N1 virus with an IC50 = 8.14 ± 3.94 µM and 2.47 ± 1.95 µM, respectively. In addition, the cyclic peptide Pc-5 was found to induce type I interferons and the expression of interferon-induced genes. An animal study showed that the cyclic peptide Pc-5 effectively inhibited H1N1 virus infection in a mouse model. Taken together, our work reveals a strategy for designing cyclic peptides and provides novel molecules with therapeutic potential against influenza A virus infection.

Retracted and republished from: "The current state of research on influenza antiviral drug development: drugs in clinical trial and licensed drugs"

Influenza viruses (IVs) threaten global human health due to the high morbidity, infection, and mortality rates. Currently, the influenza drugs recommended by the Food and Drug Administration are oseltamivir, zanamivir, peramivir, and baloxavir marboxil. These recommended antivirals are currently effective for major subtypes of IVs as the compounds target conserved domains in neuraminidase or polymerase acidic (PA) protein. However, this trend may gradually change due to the selection of antiviral drugs and the natural evolution of IVs. Therefore, there is an urgent need to develop drugs related to the treatment of influenza to deal with the next pandemic. Here, we summarized the cutting-edge research in mechanism of action, inhibitory activity, and clinical efficacy of drugs that have been approved and drugs that are still in clinical trials for influenza treatment. We hope this review will provide up-to-date and comprehensive information on influenza antivirals and generate hypotheses for screens and development of new broad-spectrum influenza drugs in the near future.

The current state of research on influenza antiviral drug development: drugs in clinical trial and licensed drugs

Influenza viruses (IVs) threaten global human health due to the high morbidity, infection, and mortality rates. Currently, the influenza drugs recommended by the FDA are oseltamivir, zanamivir, peramivir, and baloxavir marboxil. Notably, owing to the high variability of IVs, no drug exists that can effectively treat all types and subtypes of IVs. Moreover, the current trend of drug resistance is likely to continue as the viral genome is constantly mutating. Therefore, there is an urgent need to develop drugs related to the treatment of influenza to deal with the next pandemic. Here, we summarized the cutting-edge research in mechanism of action, inhibitory activity, and clinical efficacy of drugs that have been approved and drugs that are still in clinical trials for influenza treatment. We hope this review will provide up-to-date and comprehensive information on influenza antivirals and generate hypotheses for screens and development of new broad-spectrum influenza drugs in the near future.

Scutellaria baicalensis: a promising natural source of antiviral compounds for the treatment of viral diseases

Viruses, the smallest microorganisms, continue to present an escalating threat to human health, being the leading cause of mortality worldwide. Over the decades, although significant progress has been made in the development of therapies and vaccines against viral diseases, the need for effective antiviral interventions remains urgent. This urgency stems from the lack of effective vaccines, the severe side effects associated with current drugs, and the emergence of drug-resistant viral strains. Natural plants, particularly traditionally-used herbs, are often considered an excellent source of medicinal drugs with potent antiviral efficacy, as well as a substantial safety profile. Scutellaria baicalensis, a traditional Chinese medicine, has garnered considerable attention due to its extensive investigation across diverse therapeutic areas and its demonstrated efficacy in both preclinical and clinical trials. In this review, we mainly focused on the potential antiviral activities of ingredients in Scutellaria baicalensis, shedding light on their underlying mechanisms of action and therapeutic applications in the treatment of viral infections.

Development of Novel Herbal Compound Formulations Targeting Neuroinflammation: Network Pharmacology, Molecular Docking, and Experimental Verification

Neuroinflammation plays an important role in the onset and progression of neurodegenerative diseases. The multicomponent and multitarget approach may provide a practical strategy to address the complex pathological mechanisms of neuroinflammation. This study aimed to develop synergistic herbal compound formulas to attenuate neuroinflammation using integrated network pharmacology, molecular docking, and experimental bioassays. Eight phytochemicals with anti-neuroinflammatory potential were selected in the present study. A compound-gene target-signaling pathway network was constructed to illustrate the mechanisms of action of each phytochemical and the interactions among them at the molecular level. Molecular docking was performed to verify the binding affinity of each phytochemical and its key gene targets. An experimental study was conducted to identify synergistic interactions among the eight phytochemicals, and the associated molecular mechanisms were examined by immunoblotting based on the findings from the network pharmacology analysis. Two paired combinations, andrographolide and 6-shogaol (AN-SG) (IC50 = 2.85 μg/mL), and baicalein-6-shogaol (BA-SG) (IC50 = 3.28 μg/mL), were found to synergistically (combination index <1) inhibit the lipopolysaccharides (LPS)-induced nitric oxide production in microglia N11 cells. Network pharmacology analysis suggested that MAPK14, MAPK8, and NOS3 were the top three relevant gene targets for the three phytochemicals, and molecular docking demonstrated strong binding affinities of the phytochemicals to their coded proteins. Immunoblotting suggested that the AN-SG and BA-SG both showed prominent effects in inhibiting inducible nitric oxide synthase (iNOS) (p < 0.01 and p < 0.05, respectively) and MAPKp-p38 (both p < 0.05) compared with those induced by the LPS stimulation only. The AN-SG combination exhibited greater inhibitions of the protein expressions of iNOS (p < 0.05 vs. individual components), which may partly explain the mechanisms of the synergy observed. This study established a practical approach to developing novel herbal-compound formulations using integrated network pharmacology analysis, molecular docking, and experimental bioassays. The study provides a scientific basis and new insight into the two synergistic combinations against neuroinflammation.

Investigation of the activity of baicalein towards Zika virus

BACKGROUND

Zika virus (ZIKV) is a mosquito transmitted virus spread primarily by Aedes species mosquitoes that can cause disease in humans, particularly when infection occurs in pregnancy where the virus can have a significant impact on the developing fetus. Despite this, there remains no prophylactic agent or therapeutic treatment for infection. Baicalein is a trihydroxyflavone, that is found in some traditional medicines commonly used in Asia, and has been shown to have several activities including antiviral properties. Importantly, studies have shown baicalein to be safe and well tolerated in humans, increasing its potential utilization.

METHODS

This study sought to determine the anti-ZIKV activity of baicalein using a human cell line (A549). Cytotoxicity of baicalein was determined by the MTT assay, and the effect on ZIKV infection determined by treating A549 cells with baicalien at different time points in the infection process. Parameters including level of infection, virus production, viral protein expression and genome copy number were assessed by flow cytometry, plaque assay, western blot and quantitative RT-PCR, respectively.

RESULTS

The results showed that baicalein had a half-maximal cytotoxic concentration (CC₅₀) of > 800 µM, and a half-maximal effective concentration (EC₅₀) of 124.88 µM. Time-of-addition analysis showed that baicalein had an inhibitory effect on ZIKV infection at the adsorption and post-adsorption stages. Moreover, baicalein also exerted a significant viral inactivation activity on ZIKV (as well as on dengue virus and Japanese encephalitis virus) virions.

CONCLUSION

Baicalein has now been shown to possess anti-ZIKV activity in a human cell line.

Identification of three cultivated varieties of Scutellaria baicalensis using the complete chloroplast genome as a super-barcode

Scutellaria baicalensis has been one of the most commonly used traditional Chinese medicinal plants in China for more than 2000 years. The three new varieties cultivated could not be distinguished by morphology before flowering. It will hinder the promotion of later varieties. Chloroplast DNA has been widely used in species identification. Moreover, previous studies have shown that complete chloroplast genome sequences have been suggested as super barcodes for identifying plants. Therefore, we sequenced and annotated the complete chloroplast genomes of three cultivated varieties. The chloroplast genomes of SBW, SBR, and SBP were 151,702 bp, 151,799 bp, and 151,876 bp, which contained 85 protein-coding genes, 36 tRNA genes, and 8 rRNA genes. The analysis of the repeat sequences, codon usage, and comparison of chloroplast genomes shared a high degree of conservation. However, the sliding window results show significant differences among the three cultivated varieties in matK-rps16 and petA-psbJ. And we found that the matK-rps16 sequence can be used as a barcode for the identification of three varieties. In addition, the complete chloroplast genome contains more variations and can be used as a super-barcode to identify these three cultivated varieties. Based on the protein-coding genes, the phylogenetic tree demonstrated that SBP was more closely related to SBW, in the three cultivated varieties. Interestingly, we found that S. baicalensis and S. rehderiana are closely related, which provides new ideas for the development of S. baicalensis. The divergence time analysis showed that the three cultivated varieties diverged at about 0.10 Mya. Overall, this study showed that the complete chloroplast genome could be used as a super-barcode to identify three cultivated varieties of S. baicalensis and provide biological information, and it also contributes to bioprospecting.

Specialized metabolites from plants as a source of new multi-target antiviral drugs: a systematic review

Viral infections have always been the main global health challenge, as several potentially lethal viruses, including the hepatitis virus, herpes virus, and influenza virus, have affected human health for decades. Unfortunately, most licensed antiviral drugs are characterized by many adverse reactions and, in the long-term therapy, also develop viral resistance; for these reasons, researchers have focused their attention on investigating potential antiviral molecules from plants. Natural resources indeed offer a variety of specialized therapeutic metabolites that have been demonstrated to inhibit viral entry into the host cells and replication through the regulation of viral absorption, cell receptor binding, and competition for the activation of intracellular signaling pathways. Many active phytochemicals, including flavonoids, lignans, terpenoids, coumarins, saponins, alkaloids, etc., have been identified as potential candidates for preventing and treating viral infections. Using a systematic approach, this review summarises the knowledge obtained to date on the in vivo antiviral activity of specialized metabolites extracted from plant matrices by focusing on their mechanism of action.

Phytocompounds as a source for the development of new drugs to treat respiratory viral infections

Respiratory viruses have an important history as a threat to global health. However, this problem has been aggravated due to the appearance of new outbreaks caused by a newly discovered virus or variant. Recently, the new coronavirus (SARS-CoV-2) has been a major concern for health authorities, and it was classified as a pandemic by the World Health Organization. Secondary metabolites obtained from plants represent an alternative to the discovery of new active molecules and have already shown potential to combat different viruses. In an effort to demonstrate the broad spectrum of antiviral action from these metabolites, this work describes the compounds that were effective against the major viruses that cause respiratory infections in humans. In addition, their mechanisms of action were highlighted as an approach to better understanding the virus-bioactive substance relationship. Finally, this study warns that, although phytocompounds have a broad antiviral action spectrum, the development of products and clinical trials based on these secondary metabolites is still scarce and therefore deserves greater attention from the scientific community.

Research progress on antiviral constituents in traditional Chinese medicines and their mechanisms of action

CONTEXT

Viruses have the characteristics of rapid transmission and high mortality. At present, western medicines still lack an ideal antiviral. As natural products, many traditional Chinese medicines (TCM) have certain inhibitory effects on viruses, which has become the hotspot of medical research in recent years.

OBJECTIVE

The antiviral active ingredients and mechanisms of TCM against viral diseases was studied in combination with the pathogenesis of viral diseases and antiviral effects.

MATERIALS AND METHODS

English and Chinese literature from 1999 to 2021 was collected from databases including Web of Science, PubMed, Elsevier, Chinese Pharmacopoeia 2020 (CP), and CNKI (Chinese). Traditional Chinese medicines (TCM), active ingredients, antiviral, mechanism of action, and anti-inflammatory effect were used as the key words.

RESULTS

The antiviral activity of TCM is clarified to put forward a strategy for discovering active compounds against viruses, and provide reference for screening antivirus drugs from TCM. TCM can not only directly kill viruses and inhibit the proliferation of viruses in cells, but also prevent viruses from infecting cells and causing cytophilia. It can also regulate the human immune system, enhance human immunity, and play an indirect antiviral role.

DISCUSSION AND CONCLUSION

Based on the experimental study and antiviral mechanism of TCM, this paper can provide analytical evidence that supports the effectiveness of TCM in treating virus infections, as well as their mechanisms against viruses. It could be helpful to provide reference for the research and development of innovative TCMs with multiple components, multiple targets and low toxicity.

Potential common mechanism of four Chinese patent medicines recommended by diagnosis and treatment protocol for COVID-19 in medical observation period

The global epidemic has been controlled to some extent, while sporadic outbreaks still occur in some places. It is essential to summarize the successful experience and promote the development of new drugs. This study aimed to explore the common mechanism of action of the four Chinese patent medicine (CPMs) recommended in the Medical Observation Period COVID-19 Diagnostic and Treatment Protocol and to accelerate the new drug development process. Firstly, the active ingredients and targets of the four CPMs were obtained by the Chinese medicine composition database (TCMSP, TCMID) and related literature, and the common action targets of the four TCMs were sorted out. Secondly, the targets of COVID-19 were obtained through the gene-disease database (GeneCards, NCBI). Then the Venn diagram was used to intersect the common drug targets with the disease targets. And GO and KEGG pathway functional enrichment analysis was performed on the intersected targets with the help of the R package. Finally, the results were further validated by molecular docking and molecular dynamics analysis. As a result, a total of 101 common active ingredients and 21 key active ingredients of four CPMs were obtained, including quercetin, luteolin, acacetin, kaempferol, baicalein, naringenin, artemisinin, aloe-emodin, which might be medicinal substances for the treatment of COVID-19. TNF, IL6, IL1B, CXCL8, CCL2, IL2, IL4, ICAM1, IFNG, and IL10 has been predicted as key targets. 397 GO biological functions and 166 KEGG signaling pathways were obtained. The former was mainly enriched in regulating apoptosis, inflammatory response, and T cell activation. The latter, with 92 entries related to COVID-19, was mainly enriched to signaling pathways such as Coronavirus disease-COVID-19, Cytokine-cytokine receptor interaction, IL-17 signaling pathway, and Toll-like receptor signaling pathway. Molecular docking results showed that 19/21 of key active ingredients exhibited strong binding activity to recognized COVID-19-related targets (3CL of SARS-CoV-2, ACE2, and S protein), even better than one of these four antiviral drugs. Among them, shinflavanone had better affinity to 3CL, ACE2, and S protein of SARS-CoV-2 than these four antiviral drugs. In summary, the four CPMs may play a role in the treatment of COVID-19 by binding flavonoids such as quercetin, luteolin, and acacetin to target proteins such as ACE2, 3CLpro, and S protein and acting on TNF, IL6, IL1B, CXCL8, and other targets to participate in broad-spectrum antiviral, immunomodulatory and inflammatory responses.

Pharmacological Potential of Flavonoids against Neurotropic Viruses

Flavonoids are a group of natural compounds that have been described in the literature as having anti-inflammatory, antioxidant, and neuroprotective compounds. Although they are considered versatile molecules, little has been discussed about their antiviral activities for neurotropic viruses. Hence, the present study aimed to investigate the pharmacological potential of flavonoids in the face of viruses that can affect the central nervous system (CNS). We carried out research from 2011 to 2021 using the Pubmed platform. The following were excluded: articles not in the English language, letters to editors, review articles and papers that did not include any experimental or clinical tests, and papers that showed antiviral activities against viruses that do not infect human beings. The inclusion criteria were in silico predictions and preclinical pharmacological studies, in vitro, in vivo and ex vivo, and clinical studies with flavonoids, flavonoid fractions and extracts that were active against neurotropic viruses. The search resulted in 205 articles that were sorted per virus type and discussed, considering the most cited antiviral activities. Our investigation shows the latest relevant data about flavonoids that have presented a wide range of actions against viruses that affect the CNS, mainly influenza, hepatitis C and others, such as the coronavirus, enterovirus, and arbovirus. Considering that these molecules present well-known anti-inflammatory and neuroprotective activities, using flavonoids that have demonstrated both neuroprotective and antiviral effects could be viewed as an alternative for therapy in the course of CNS infections.

Efficacy and safety of Qinxiang Qingjie oral solution for the treatment of influenza in children: a randomized, double-blind, multicenter clinical trial

BACKGROUND

Qinxiang Qingjie (QXQJ), an oral solution containing various Chinese herbs, is indicated for pediatric upper respiratory tract infections. The treatment of influenza also shows potential advantages in shortening the duration of illness and improving symptoms. However, there is still a lack of high-quality clinical evidence to support this. The trial was to explore the efficacy and safety of QXQJ for treating pediatric influenza and provide an evidence-based basis for expanding its applicability.

METHODS

A randomized, double-blind, double-dummy, positive-controlled, multicenter clinical trial was conducted in 14 hospitals in China. Children aged 1-13 years with influenza and "exterior and interior heat syndromes" as defined by traditional Chinese medicine (TCM) were randomly assigned to two groups with 1:1 radio. Children in the test group received QXQJ oral solution and oseltamivir simulant, while the control group received oseltamivir phosphate granules and QXQJ simulant. The duration of treatment was five days, followed by a two-day follow-up period. The primary endpoint was the clinical recovery time. Secondary endpoints included the time to defervescence, incidences of complications and severe or critical influenza, negative conversion rate, improvement of TCM syndromes, and safety profiles of the therapeutics, which mainly contained the adverse clinical events and adverse drug reactions.

RESULTS

A total of 231 children were randomized to either the QXQJ (n=117) or oseltamivir (n=114) group. The FAS and PPS results showed that both groups experienced a median clinical recovery time of three days (P>0.05). The median time to defervescence of both groups were 36 hours in FAS and PPS (P>0.05), and two groups did not differ in terms of the other secondary endpoints (P>0.05). 14 patients (12.39%) in the QXQJ group and 14 patients (12.50%) in the oseltamivir group reported at least one adverse event, respectively. One serious adverse event occurred in the QXQJ group. There was no significant difference in the incidence of adverse events or adverse drug reactions between the groups.

CONCLUSIONS

The efficacy of QXQJ oral solution was comparable to that of oseltamivir for treating influenza in children, with an acceptable safety profile.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR1900021060.

Influenza antivirals and animal models

Influenza A and B viruses are among the most prominent human respiratory pathogens. About 3-5 million severe cases of influenza are associated with 300 000-650 000 deaths per year globally. Antivirals effective at reducing morbidity and mortality are part of the first line of defense against influenza. FDA-approved antiviral drugs currently include adamantanes (rimantadine and amantadine), neuraminidase inhibitors (NAI; peramivir, zanamivir, and oseltamivir), and the PA endonuclease inhibitor (baloxavir). Mutations associated with antiviral resistance are common and highlight the need for further improvement and development of novel anti-influenza drugs. A summary is provided for the current knowledge of the approved influenza antivirals and antivirals strategies under evaluation in clinical trials. Preclinical evaluations of novel compounds effective against influenza in different animal models are also discussed.

Do Uncommon Plant Phenolic Compounds Have Uncommon Properties? A Mini Review on Novel Flavonoids

Unique plants and their properties, once considered synonymous to medicine, remain a potent source for new compounds in modern science. Plant polyphenols and natural products continue to be investigated for effective treatments for the most persistent of human ailments. In this review, fifty novel plant phenolic compounds have been compiled and briefly described from the previous five years. Select compounds and notable plant species from genus Morinda and Sophora are further expanded on. Traditional medicine plants often contain rich and diverse mixtures of flavonoids, from which rare compounds should receive attention. The bioactivity of crude plant extracts, purified compounds and mixtures can differ greatly, requiring that these interactions and mechanisms of action be investigated in greater detail. Novel applications of uncommon natural products, namely mimosine and juglone, are explored within this review. The 2019 coronavirus pandemic has resulted in abrupt spike of related scientific publications: speculation is made regarding plant natural products and future of antiviral drug discovery.

Flavonoids as potential phytotherapeutics to combat cytokine storm in SARS-CoV-2

Emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection, COVID-19, has become the global panic since December 2019, which urges the global healthcare professionals to identify novel therapeutics to counteract this pandemic. So far, there is no approved treatment available to control this public health issue; however, a few antiviral agents and repurposed drugs support the patients under medical supervision by compromising their adverse effects, especially in emergency conditions. Only a few vaccines have been approved to date. In this context, several plant natural products-based research studies are evidenced to play a crucial role in immunomodulation that can prevent the chances of infection as well as combat the cytokine release storm (CRS) generated during COVID-19 infection. In this present review, we have focused on flavonoids, especially epicatechin, epigallocatechin gallate, hesperidin, naringenin, quercetin, rutin, luteolin, baicalin, diosmin, ge nistein, biochanin A, and silymarin, which can counteract the virus-mediated elevated levels of inflammatory cytokines leading to multiple organ failure. In addition, a comprehensive discussion on available in silico, in vitro, and in vivo findings with critical analysis has also been evaluated, which might pave the way for further development of phytotherapeutics to identify the potential lead candidatetoward effective and safe management of the SARS-CoV-2 disease.

Safety, tolerability, pharmacokinetics, and food effect of baicalein tablets in healthy Chinese subjects: A single-center, randomized, double-blind, placebo-controlled, single-dose phase I study

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellaria baicalensis (Huang-Qin in Chinese) is a dry root of the perennial herb Scutellaria baicalensis Georgi, which has been used extensively in current prescriptions. Scutellaria baicalensis is an herb high in flavonoids, and baicalein is the one flavonoid found in the highest amount in Scutellaria baicalensis.

AIM OF THE STUDY

Influenza virus could cause mild respiratory tract illness to severe pneumonia and even death. Baicalein has been proved to be one of the effective components against the influenza virus. However, there have been few reports on human trials of baicalein. The purpose of this study was to evaluate the safety of baicalein in vivo and analyze its pharmacokinetic characteristics.

MATERIALS AND METHODS

Three randomized studies were conducted to evaluate the pharmacokinetics (PK), safety, tolerability, and food effects of baicalein tablets. In the 7-month single-dose safety study, 60 subjects were enrolled and randomized to receive 100-800 mg baicalein tablets or placebo. In the single-dose PK study, 40 subjects were enrolled and randomized to receive 200 mg, 400 mg, 600 mg, 800 mg baicalein tablets. In the study of food effect on PK of baicalein, an additional 10 subjects were enrolled in the 400 mg group, this part of the trial lasted for 7 months. Blood and urine samples for PK analysis were collected at a pre-specified time. PK properties in both fasted and fed states were evaluated, as well as safety and tolerability.

RESULTS

Among the 80 subjects who were evaluable for the single-dose safety and tolerability, 56 adverse events (AEs) were observed in 32/80 subjects, of which 49 events were from 28/68 subjects in baicalein group and 7 events were from 4/12 subjects in placebo group. All AEs were mild and resolved without any medical intervention. The most common AEs were elevated high-sensitivity C-reactive protein (hs-CRP) level and high triglycerides. After a single administration of baicalein tablets (200 mg, 400 mg, 600 mg, or 800 mg), C_max were 280.44, 628.80, 845.20, 489.55 ng/mL; AUC_0-∞ were 2035.57, 2939.31, 4494.88, and 3754.43 h*ng/mL, respectively. And t_1/2z ranged from 7.80 to 14.91 h. The exposure of baicalein and its metabolites increased in a less than dose-proportional manner.

CONCLUSION

Baicalein tablets within the studied dose range were safe and well-tolerated in healthy Chinese subjects with no serious or severe adverse effects. Further investigation will be needed to assess the safety and efficacy in the target patients.

The comprehensive study on the therapeutic effects of baicalein for the treatment of COVID-19 in vivo and in vitro

Baicalein is the main active compound of Scutellaria baicalensis Georgi, a medicinal herb with multiple pharmacological activities, including the broad anti-virus effects. In this paper, the preclinical study of baicalein on the treatment of COVID-19 was performed. Results showed that baicalein inhibited cell damage induced by SARS-CoV-2 and improved the morphology of Vero E6 cells at a concentration of 0.1 μM and above. The effective concentration could be reached after oral administration of 200 mg/kg crystal form β of baicalein in rats. Furthermore, baicalein significantly inhibited the body weight loss, the replication of the virus, and relieved the lesions of lung tissue in hACE2 transgenic mice infected with SARS-CoV-2. In LPS-induced acute lung injury of mice, baicalein improved the respiratory function, inhibited inflammatory cell infiltration in the lung, and decreased the levels of IL-1β and TNF-α in serum. In conclusion, oral administration of crystal form β of baicalein could reach its effective concentration against SARS-CoV-2. Baicalein could inhibit SARS-CoV-2-induced injury both in vitro and in vivo. Therefore, baicalein might be a promising therapeutic drug for the treatment of COVID-19.

The main bioactive compounds of Scutellaria baicalensis Georgi. for alleviation of inflammatory cytokines: A comprehensive review

Scutellaria baicalensis Georgi., a plant used in traditional Chinese medicine, has multiple biological activities, including anti-inflammatory, antiviral, antitumor, antioxidant, and antibacterial effects, and can be used to treat respiratory tract infections, pneumonia, colitis, hepatitis, and allergic diseases. The main active substances of S. baicalensis, baicalein, baicalin, wogonin, wogonoside, and oroxylin A, can act directly on immune cells such as lymphocytes, macrophages, mast cells, dendritic cells, monocytes, and neutrophils, and inhibit the production of the inflammatory cytokines IL-1β, IL-6, IL-8, and TNF-α, and other inflammatory mediators such as nitric oxide, prostaglandins, leukotrienes, and reactive oxygen species. The molecular mechanisms underlying the immunomodulatory and anti-inflammatory effects of the active compounds of S. baicalensis include downregulation of toll-like receptors, activation of the Nrf2 and PPAR signaling pathways, and inhibition of the nuclear thioredoxin system and inflammation-associated pathways such as those of MAPK, Akt, NFκB, and JAK-STAT. Given that in addition to the downregulation of cytokine production, the active constituents of S. baicalensis also have antiviral and antibacterial effects, they may be more promising candidate therapeutics for the prevention of infection-related cytokine storms than are drugs having only antimicrobial or anti-inflammatory activities.

Regulation of Nrf2/ARE Pathway by Dietary Flavonoids: A Friend or Foe for Cancer Management?

The nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway is an important cell signaling mechanism in maintaining redox homeostasis in humans. The role of dietary flavonoids in activating Nrf2/ARE in relation to cancer chemoprevention or cancer promotion is not well established. Here we summarize the dual effects of flavonoids in cancer chemoprevention and cancer promotion with respect to the regulation of the Nrf2/ARE pathway, while underlying the possible cellular mechanisms. Luteolin, apigenin, quercetin, myricetin, rutin, naringenin, epicatechin, and genistein activate the Nrf2/ARE pathway in both normal and cancer cells. The hormetic effect of flavonoids has been observed due to their antioxidant or prooxidant activity, depending on the concentrations. Reported in vitro and in vivo investigations suggest that the activation of the Nrf2/ARE pathway by either endogenous or exogenous stimuli under normal physiological conditions contributes to redox homeostasis, which may provide a mechanism for cancer chemoprevention. However, some flavonoids, such as luteolin, apigenin, myricetin, quercetin, naringenin, epicatechin, genistein, and daidzein, at low concentrations (1.5 to 20 µM) facilitate cancer cell growth and proliferation in vitro. Paradoxically, some flavonoids, including luteolin, apigenin, and chrysin, inhibit the Nrf2/ARE pathway in vitro. Therefore, even though flavonoids play a major role in cancer chemoprevention, due to their possible inducement of cancer cell growth, the effects of dietary flavonoids on cancer pathophysiology in patients or appropriate experimental animal models should be investigated systematically.

An integrated strategy for profiling the chemical components of Scutellariae Radix and their exogenous substances in rats by ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry

RATIONALE

Traditional Chinese medicines (TCMs) attract worldwide attention because of their effects in clinical application recorded in China historical ancient codes and in records, such as 'Treatise on Febrile Diseases'. With the developments of drug analysis and research, evaluating the in vivo substances in TCMs has become of great importance. Scutellariae Radix (SR, named as huang-qing in China), the root of Scutellaria baicalensis Georgi, has shown favorable clinical effects and safety in the treatment of infection diseases; however, its in vivo compounds are unclear and need detailed investigation.

METHODS

An ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC/QTOF MS) method coupled to an integrated strategy involving diagnostic ions, neutral losses and a prediction platform was used to explore the constituents of SR, and their exogenous substances in rats.

RESULTS

A total of 118 chemical constituents mainly featuring five chemical structure types (flavone C-glycosides, flavone O-glycosides, free flavones, flavanones and phenylethanoid glycosides) were identified or tentatively characterized in SR, and 175 xenobiotics (68 prototypes and 107 metabolites) were profiled in rat plasma, urine, bile and feces after ingestion of SR. The metabolites were classified into four related chemical groups: flavone C-glycosides, flavone O-glycosides, flavanones and phenylethanoid glycosides. Phase II metabolism reactions, such as glucuronidation and sulfation, were the major metabolic reactions in addition to phase I reactions of hydrolysis and hydrogenation. The corresponding main metabolic features of SR in rats were also elucidated.

CONCLUSIONS

The metabolism of SR, as a whole, was systemically revealed for the first time, and our work also provided meaningful information for pharmacokinetics studies and pharmacological analysis of SR in future work.

Baicalein enhanced cisplatin sensitivity of gastric cancer cells by inducing cell apoptosis and autophagy via Akt/mTOR and Nrf2/Keap 1 pathway

Baicalein is a natural flavonoid with various pharmacological activities including antitumor. The synergistic anti-cancer effect of the combination of baicalein and Cisplatin (DDP) on gastric cancer (GC) has not been reported. MTT assay and colony formation assay were used to determine the inhibitory effect of the combination of baicalein and DDP on cell survival. Invasive assay was performed to test the effects of baicalein and DDP on cell invasive capability. A flow cytometric analysis was conducted to determine the apoptosis-induced effects of baicalein on GC cells, especially SGC-7901/DDP (resistant to DDP). Confocal laser microscope and real-time PCR were used to test autophagy-induced effects of baicalein on SGC-7901 and SGC-7901/DDP cells. Western blotting was performed to investigate the molecular mechanisms of baicalein inducing apoptosis and autophagy. Our study showed that baicalein could inhibit cell proliferation of MGC-803, HGC-27, SGC-7901 and SGC-7901/DDP, and the inhibitory effect was extremely enhanced when combining with DDP. Additionally, combination of baicalein and DDP suppressed the invasive capability and induced apoptosis and autophagy in both SGC-7901 and SGC-7901/DDP, and the effect was stronger than that of DDP or baicalein alone. The further molecular mechanism analysis indicated that baicalein modulated the activities of Akt/mTOR and Nrf2/Keap 1 signaling. Our study demonstrated that baicalein enhanced DDP sensitivity of SGC-7901/DDP gastric cancer cells by inducing apoptosis and autophagy via Akt/mTOR and Nrf2/Keap 1 pathway.

Potential Targets for Treatment of Coronavirus Disease 2019 (COVID-19): A Review of Qing-Fei-Pai-Du-Tang and Its Major Herbs

COVID-19 has been declared a pandemic by WHO on March 11, 2020. No specific treatment and vaccine with documented safety and efficacy for the disease have been established. Hence it is of utmost importance to identify more therapeutics such as Chinese medicine formulae to meet the urgent need. Qing Fei Pai Du Tang (QFPDT), a Chinese medicine formula consisting of 21 herbs from five classical formulae has been reported to be efficacious on COVID-19 in 10 provinces in mainland China. QFPDT could prevent the progression from mild cases and shorten the average duration of symptoms and hospital stay. It has been recommended in the 6th and 7th versions of Clinical Practice Guideline on COVID-19 in China. The basic scientific studies, supported by network pharmacology, on the possible therapeutic targets of QFPDT and its constituent herbs including Ephedra sinica, Bupleurum chinense, Pogostemon cablin, Cinnamomum cassia, Scutellaria baicalensis were reviewed. The anti-oxidation, immuno-modulation and antiviral mechanisms through different pathways were collated. Two clusters of actions identified were cytokine storm prevention and angiotensin converting enzyme 2 (ACE2) receptor binding regulation. The multi-target mechanisms of QFPDT for treating viral infection in general and COVID-19 in particular were validated. While large scale clinical studies on QFPDT are being conducted in China, one should use real world data for exploration of integrative treatment with inclusion of pharmacokinetic, pharmacodynamic and herb-drug interaction studies.

Comparison Study on the Contents of Eight Flavonoids in three Different Processed Products of Scutellariae Radix using Ultra-high Performance Liquid Chromatography Coupled With Triple-Quadrupole Mass Spectrometry

Background:

The simultaneous determination of multiple components in a sample is an important factor in the quality control of traditional Chinese medicines and can give an indication of potential clinical applications.

Introduction:

A rapid and sensitive method has been introduced for the simultaneous quantitative analysis of eight bioactive flavonoid constituents from Scutellariae Radix using ultra-high performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry.

Methods:

The separation was performed on a Waters Acquity UPLC C18 column (2.1 mm×100 mm, 1.7 μm), under optimized mass spectrometry conditions, with a flow rate of 0.3 mL/min. The column temperature was maintained at 35°C and the injection volume was 3 μL.

Results:

The method showed a good linear relationship of each component; all R2 values were above 0.9990 in the experiment. The RSDs of the precision test, repeatability test, stability test and recovery test were all not more than 2.86 %. We found that the total percentage amounts of the eight flavonoids were 22.19%, 18.63% and 10.86% in Raw Scutellariae Radix (RSR), Wine Scutellaria Radix (WSR) and Scutellaria Radix Charcoal (SRC) respectively.

Conclusion:

The method was successfully applied to the simultaneous determination of the eight bioactive flavonoids of Raw Scutellariae Radix, Wine Scutellaria Radix and Scutellaria Radix Charcoal.

Inhibitory Activity of Scutellaria baicalensis Flavonoids against Tick-Borne Encephalitis Virus

We studied virus-inhibiting activity of Baikal skullcap (Scutellaria baicalensis) flavonoids against tick-borne encephalitis virus using various model schemes. The half-maximum cytotoxic concentration (CC₅₀) for the plant extract was found (363.9±58.6 μg/ml). Based on the CC₅₀ and IC₅₀, selective index (SI) was calculated for viricidal (53.4), preventive (50.5), and direct antiviral actions (39.1) and for-intracellular replication of the virus (40.4). Suppression of virus reproduction ≥2.0 lg TCID₅₀ was observed at extract concentration ≥5 μg/ml (viricidal effect), ≥11.2 μg/ml (preventive and direct antiviral effects), and ≥9 μg/ml (intracellular replication). Flavonoids of Baikal skullcap extract produced an in vitro inhibitory effect on tick-borne encephalitis virus due to their direct viricidal activity and direct inhibition of adsorption and intracellular replication of tick-borne encephalitis virus, which determines their value as highly effective antiviral drugs.

3D-quantitative structure-activity relationship and antiviral effects of curcumin derivatives as potent inhibitors of influenza H1N1 neuraminidase

Curcumin derivatives have been shown to inhibit replication of human influenza A viruses (IAVs). However, it is not clear whether curcumin and its derivatives can inhibit neuraminidase (NA) of influenza virus. In this study, a meaningful 3D quantitative structure–activity relationship model (comparative molecular field analysis R² = 0.997, q² = 0.527, s = 0.064, F = 282.663) was built to understand the chemical–biological interactions between their activities and neuraminidase. Molecular docking was used to predict binding models between curcumin derivatives and neuraminidase. Real-time polymerase chain reactions showed that the five active curcumin derivatives might have direct effects on viral particle infectivity in H1N1-infected lung epithelial (MDCK) cells. Neuraminidase activation assay showed that five active curcumin derivatives decreased H1N1-induced neuraminidase activation in MDCK cells. Indirect immunofluorescence assay indicated that two active curcumin derivatives (tetramethylcurcumin and curcumin) down-regulated the nucleoprotein expression. Curcumin inhibited IAV in vivo. The therapeutic mechanism of curcumin in the treatment of influenza viral pneumonia is related to improving the immune function of infected mice and regulating secretion of tumor necrosis-α, interleukin-6, and interferon-γ. These results indicate that curcumin derivatives inhibit IAV by blocking neuraminidase in the cellular model and curcumin also has anti-IAV activity in the animal model.

Single enzyme nanoparticle, an effective tool for enzyme replacement therapy

The term "single enzyme nanoparticle" (SEN) refers to a chemically or biologically engineered single enzyme molecule. SENs are distinguished from conventional protein nanoparticles in that they can maintain their individual structure and enzymatic activity following modification. Furthermore, SENs exhibit enhanced properties as biopharmaceuticals, such as reduced antigenicity, and increased stability and targetability, which are attributed to the introduction of specific moieties, such as poly(ethylene glycol), carbohydrates, and antibodies. Enzyme replacement therapy (ERT) is a crucial therapeutic option for controlling enzyme-deficiency-related disorders. However, the unfavorable properties of enzymes, including immunogenicity, lack of targetability, and instability, can undermine the clinical significance of ERT. As shown in the cases of Adagen®, Revcovi®, Palynziq®, and Strensiq®, SEN can be an effective technology for overcoming these obstacles. Based on these four licensed products, we expect that additional SENs will be introduced for ERT in the near future. In this article, we review the concepts and features of SENs, as well as their preparation methods. Additionally, we summarize different types of enzyme deficiency disorders and the corresponding therapeutic enzymes. Finally, we focus on the current status of SENs in ERT by reviewing FDA-approved products.

Exploring the effective materials of flavonoids-enriched extract from Scutellaria baicalensis roots based on the metabolic activation in influenza A virus induced acute lung injury

Flavonoids-enriched extract from Scutellaria baicalensis roots (FESR) ameliorated influenza A virus (IAV) induced acute lung injury (ALI) in mice by inhibiting the excessive activation of complement system in vivo. However, FESR had no anti-complementary activity in vitro. In order to reveal the effective materials of FESR for the treatment of IAV-induced ALI, the present research explored the metabolic process of FESR both in nomal and IAV infected mice by the method of UHPLC-ESI-LTQ/MS, as well as the metabolic activating mechanism. The results showed that the inactive flavonoid glycosides of FESR were partly metabolized into anti-complementary aglycones in vivo, mainly including 5,7,4'-trihydroxy-8-methoxy-flavone, norwogonin, baicalein, wogonin, oroxylin A and chrysin. Moreover, compared with the normal mice, IAV-induced ALI mice exhibited more efficient on producing and absorbing these active metabolites, with AUC_0-t and C_max in plasma and concentrations in lungs and intestines markedly elevated in the IAV treated groups (P <  0.05). Interestingly, the intestinal bacteria from IAV-induced ALI mice showed stronger β-glucuronidase activity and also had higher efficiency on transforming FESR to the flavonoid aglycones. These findings suggested that the anti-complementary aglycones produced by metabolic activation in vivo should be the potential effective materials of FESR against IAV infections, and intestinal bacteria might play an important role on the higher bioavailability of FESR in IAV infected mice. Additionally, the animals under the pathological state are more suitable for the metabolic study of traditional Chinese medicine.

Baicalein Induces Autophagy and Apoptosis through AMPK Pathway in Human Glioma Cells

Baicalein (BAI) is a natural flavonoid. It has been shown that BAI has anticancer effects, but the molecular mechanism is still unclear. The aim of the current study was to confirm whether or not BAI triggers autophagy and induces AMPK activation in glioma U251 cells. The Ad-mcherry-GFP-LC3B adenovirus experiments indicated that BAI induces glioma cell autophagy. Western blotting showed that the level of LC3II expression increased with the time and concentration of BAI. Following treatment with chloroquine, the expression of LC3 was enhanced Immunofluorescence also confirmed this result. At the same time, cleaved caspase-3, DAPI staining, and JC-1 staining revealed that apoptosis was also induced in the induction of autophagy. In addition, we found that BAI activates phosphorylation of AMPK, which is further confirmed using compound C in this process. When the phosphorylation of AMPK was inhibited, autophagy, and apoptosis were also inhibited. In conclusion, BAI induces autophagy and apoptosis through AMPK pathway. Surprisingly, our research provides new insight with the function of anticancer of BAI, and the potential of the promotion in glioma cell apoptosis might be related to autophagy activation. These results demonstrate the anticancer activity of BAI, which can be used as potential therapeutic agents for cancer therapy.

A comprehensive review on phytochemistry, pharmacology, and flavonoid biosynthesis of Scutellaria baicalensis

CONTEXT

Scutellaria baicalensis Georgi (Lamiaceae) is a popular medicinal plant. Its roots are used as the famous traditional Chinese medicine Huang-Qin, which is recorded in Chinese Pharmacopoeia, European Pharmacopoeia, and British Pharmacopoeia.

OBJECTIVE

This review comprehensively summarizes research progress in phytochemistry, pharmacology, and flavonoid biosynthesis of S. baicalensis.

METHODS

English and Chinese literature from 1973 to March 2018 was collected from databases including Web of Science, SciFinder, PubMed, Elsevier, Baidu Scholar (Chinese), and CNKI (Chinese). Scutellaria baicalensis, chemical constituents, phytochemistry, biological activities, and biosynthesis were used as the key words.

RESULTS

A total of 126 small molecules (1-126) and 6 polysaccharides have been isolated from S. baicalensis. The small molecules can be classified into four structural types, namely, free flavonoids, flavonoid glycosides, phenylethanoid glycosides, and other small molecules. Extracts of S. baicalensis and its major chemical constituents have been reported to possess anti-viral, anti-tumor, anti-bacterial, antioxidant, anti-inflammatory, hepatoprotective, and neuroprotective activities. Key steps in the biosynthetic pathways of Scutellaria flavonoids have also been summarized.

CONCLUSIONS

This article could be helpful for researchers who are interested in the chemical constituents, bioactivities, biosynthesis, and clinical applications of S. baicalensis.

Antichronic Gastric Ulcer Effect of Zinc-Baicalin Complex on the Acetic Acid-Induced Chronic Gastric Ulcer Rat Model

Background

Baicalin (BA) has been shown to have anti-inflammatory and antioxidant activity. Zinc is a nutrient element.

Objective

This study is aimed at investigating the antichronic gastric ulcer activity of Zn-Baicalin complex (BA-Zn) and its related mechanisms in an acetic acid-induced gastric ulcer rat model.

Results

The severely ulcerated gastric mucosa of model rats had lower GSH-Px (52.21 ± 7.13) and SOD (7.03 ± 0.10) activity, and higher MDA (2.39 ± 0.03) content compared to sham rats. BA-Zn reduced the gastric ulcer index in a dose-dependent manner, significantly increased SOD activity and GSH-Px level, and reduced the MDA content and IL-8 and TNF-α levels in the gastric mucosa. BA-Zn (6.5 and 13 mg/kg) exerted a greater antiulcerogenic effect than both BA and zinc-gluconate, leading to a reduced ulcer index (18.43 ± 1.11, 15.00 ± 1.44), decreased MDA content (1.33 ± 0.07, 0.63 ± 0.01), and increased SOD activity (17.62 ± 0.11, 20.12 ± 0.32) and GSH-Px levels (102.12 ± 9.11, 120.25 ± 9.07). In addition, our results from Western blot suggested that BA-Zn (6.5 and 13 mg/kg) has a greater antiulcerogenic effect than both BA and zinc-gluconate.

Conclusion

The BA-Zn complex possesses greater antichronic gastric ulcer properties compared to BA and zinc-gluconate due to its ability of oxidation resistance and anti-inflammatory effects.

Investigating Different Mechanisms of Action in Combination Therapy for Influenza

Combination therapy for influenza can have several benefits, from reducing the emergence of drug resistant virus strains to decreasing the cost of antivirals. However, there are currently only two classes of antivirals approved for use against influenza, limiting the possible combinations that can be considered for treatment. However, new antivirals are being developed that target different parts of the viral replication cycle, and their potential for use in combination therapy should be considered. The role of antiviral mechanism of action in the effectiveness of combination therapy has not yet been systematically investigated to determine whether certain antiviral mechanisms of action pair well in combination. Here, we use a mathematical model of influenza to model combination treatment with antivirals having different mechanisms of action to measure peak viral load, infection duration, and synergy of different drug combinations. We find that antivirals that lower the infection rate and antivirals that increase the duration of the eclipse phase perform poorly in combination with other antivirals.

Antiviral and Antioxidant Activity of a Hydroalcoholic Extract from Humulus lupulus L

A hydroalcoholic extract from female inflorescences of Humulus lupulus L. (HOP extract) was evaluated for its anti-influenza activity. The ability of the extract to interfere with different phases of viral replication was assessed, as well as its effect on the intracellular redox state, being unbalanced versus the oxidative state in infected cells. The radical scavenging power, inhibition of lipoperoxidation, and ferric reducing activity were assayed as antioxidant mechanisms. A phytochemical characterization of the extract was also performed. We found that HOP extract significantly inhibited replication of various viral strains, at different time from infection. Viral replication was partly inhibited when virus was incubated with extract before infection, suggesting a direct effect on the virions. Since HOP extract was able to restore the reducing conditions of infected cells, by increasing glutathione content, its antiviral activity might be also due to an interference with redox-sensitive pathways required for viral replication. Accordingly, the extract exerted radical scavenging and reducing effects and inhibited lipoperoxidation and the tBOOH-induced cytotoxicity. At phytochemical analysis, different phenolics were identified, which altogether might contribute to HOP antiviral effect. In conclusion, our results highlighted anti-influenza and antioxidant properties of HOP extract, which encourage further in vivo studies to evaluate its possible application.

Antiviral effects and mechanisms of Yinhuapinggan granule against H1N1 influenza virus infection in RAW264.7 cells

Yinhuapinggan granule (YHPG), a modified prescription based on Ma-Huang-Tang (MHT), is used in traditional Chinese medicine (TCM) to treat influenza, cough, and viral pneumonia. In this study, we investigated the antiviral effects of YHPG by means of pre-, post-, and co-treatment, and its underlying mechanisms on regulating the levels of inflammatory-related cytokines, modulating the mRNA expressions of interferon-stimulated genes in influenza virus-infected murine macrophage cells (RAW264.7), and evaluating the protein expressions of key effectors in the Type I IFN and pattern recognition receptor (PRRs) signaling pathways. The results showed that YHPG markedly inhibited influenza virus (IFV) replication in pre-, post- and co-treatment assay, especially in post-treatment assay. Antiviral mechanisms studies revealed that YHPG (500 and 250 μg/mL) significantly up-regulated levels of IFN-β, IFN-stimulated genes (Mx-1, ISG-15 and ISG-56) compared with the IFV control group, while the levels of IL-6 and TNF-α were significantly down-regulated. Furthermore, western blot analysis results revealed that the protein expressions of the phosphorylated forms of TBK1, IRF3, ERK1/2, P38 MAPK and NF-κB p65 were significantly down-regulated in RAW264.7 cells with the YHPG (500 and 250 μg/mL) treatment, while the expression of the phosphorylated form of STAT1 was significantly enhanced. Based on these results, YHPG had antiviral effects in IFV-infected RAW264.7 cells, which might be associated with regulation of the inflammatory cytokines production, evaluation of the levels of IFN-stimulated genes, and modulation of the protein expressions of key effectors in the Type I IFN and PRRs signaling pathways.

A novel matrix dispersion based on phospholipid complex for improving oral bioavailability of baicalein: preparation, in vitro and in vivo evaluations

Phospholipid complex is one of the most successful approaches for enhancing oral bioavailability of poorly absorbed plant constituents. But the sticky property of phospholipids results in an unsatisfactory dissolution of drugs. In this study, a matrix dispersion of baicalein based on phospholipid complex (BaPC-MD) was first prepared by a discontinuous solvent evaporation method, in which polyvinylpyrrolidone-K30 (PVP-K30) was employed for improving the dispersibility of baicalein phospholipid complex (BaPC) and increasing dissolution of baicalein. The combination ratio of baicalein and phospholipids in BaPC-MD was 99.39% and baicalein was still in a complete complex state with phospholipid in BaPC-MD. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR) analyzes demonstrated that baicalein was fully transformed to an amorphous state in BaPC-MD and phospholipid complex formed. The water-solubility and n-octanol solubility of baicalein in BaPC-MD significantly increased compared with those of pure baicalein. Compared with baicalein and BaPC, the cumulative dissolution of BaPC-MD at 120 min increased 2.77- and 1.23-fold, respectively. In vitro permeability study in Caco-2 cells indicated that the permeability of BaPC-MD was remarkably higher than those of baicalein and BaPC. Pharmacokinetic study showed that the average Cmax of BaPC-MD was significantly increased compared to baicalein and BaPC. AUC0-14 h of BaPC-MD was 5.01- and 1.91-fold of baicalein and BaPC, respectively. The novel BaPC-MD significantly enhanced the oral bioavailability of baicalein by improving the dissolution and permeability of baicalein without destroying the complexation state of baicalein and phospholipids. The current drug delivery system provided an optimal strategy to significantly enhance oral bioavailability for poorly water-soluble drugs.

Antiviral activity of chlorogenic acid against influenza A (H1N1/H3N2) virus and its inhibition of neuraminidase

Lonicera japonica Thunb, rich in chlorogenic acid (CHA), is used for viral upper respiratory tract infection treatment caused by influenza virus, parainfluenza virus, and respiratory syncytial virus, ect in China. It was reported that CHA reduced serum hepatitis B virus level and death rate of influenza virus-infected mice. However, the underlying mechanisms of CHA against the influenza A virus have not been fully elucidated. Here, the antiviral effects and potential mechanisms of CHA against influenza A virus were investigated. CHA revealed inhibitory against A/PuertoRico/8/1934(H1N1) (EC₅₀ = 44.87 μM), A/Beijing/32/92(H3N2) (EC₅₀ = 62.33 μM), and oseltamivir-resistant strains. Time-course analysis showed CHA inhibited influenza virus during the late stage of infectious cycle. Indirect immunofluorescence assay indicated CHA down-regulated the NP protein expression. The inhibition of neuraminidase activity confirmed CHA blocked release of newly formed virus particles from infected cells. Intravenous injection of 100 mg/kg/d CHA possessed effective antiviral activity in mice, conferring 60% and 50% protection from death against H1N1 and H3N2, reducing virus titres and alleviating inflammation in the lungs effectively. These results demonstrate that CHA acts as a neuraminidase blocker to inhibit influenza A virus both in cellular and animal models. Thus, CHA has potential utility in the treatment of the influenza virus infection.

Protective effects of phillyrin against influenza A virus in vivo

Influenza A virus infection represents a great threat to public health. However, owing to side effects and the emergence of resistant virus strains, the use of currently available anti-influenza drugs may be limited. In order to identify novel anti-influenza drugs, we investigated the antiviral effects of phillyrin against influenza A virus infection in vivo. The mean survival time, lung index, viral titers, influenza hemagglutinin (HA) protein and serum cytokines levels, and histopathological changes in lung tissue were examined. Administration of phillyrin at a dose of 20 mg/kg/day for 3 days significantly prolonged the mean survival time, reduced the lung index, decreased the virus titers and interleukin-6 levels, reduced the expression of HA, and attenuated lung tissue damage in mice infected with influenza A virus. Taken together, these data showed that phillyrin had potential protective effects against infection caused by influenza A virus.

Latest research progress in the correlation between baicalein and breast cancer invasion and metastasis

Breast cancer is one of the most commonly occurring female malignant tumors. According to the 2012 GLOBOCAN statistics, produced by the International Agency for Research On Cancer ('IARC'), nearly 1.7 million women were diagnosed with breast cancer, with 522,000 related deaths: An increase in the incidence of breast cancer and associated mortality by nearly 18% from 2008. Metastasis is the final step in breast cancer progression, and represents the most common cause of mortality in patients with breast cancer. Therefore, a search for low-toxicity, safe and effective anti-breast cancer drugs in the form of natural compounds has become an intense focus of research. Baicalein, a widely used Chinese herbal medicine, has extensive antitumor activity. The present review briefly describes the research that has been performed on the association between baicalein and breast cancer metastasis, and further illustrates the influence of baicalein on the underlying mechanisms of breast cancer metastasis, adding a novel theory basis for baicalein antitumor research. In conclusion, baicalein may represent a promising target for the prevention and therapy of breast cancer.

Antiviral activity of SA-2 against influenza A virus in vitro/vivo and its inhibition of RNA polymerase

A target-free and cell-based approach was applied to evaluate the anti-influenza properties of six newly synthesized benzoic acid derivatives. SA-2, the ethyl 4-(2-hydroxymethyl-5-oxopyrrolidin-1-yl)-3-[3-(3-methylbenzoyl)-thioureido] benzoate (compound 2) was screened as a potential drug candidate. In a cytopathic effect assay, SA-2 dose dependently inhibited H1N1, H3N2 and the oseltamivir-resistant mutant H1N1-H275Y influenza viruses in both virus-infected MDCK and A549 cells, with 50% effective concentrations (EC50) in MDCK cells of 9.6, 19.2 and 19.8 μM respectively, and 50% cytotoxic concentration (CC50) of 444.5 μM, showing competitive antiviral activity with oseltamivir in vitro. Orally administered SA-2 effectively protected mice infected with lethal doses of H1N1 or oseltamivir-resistant strain H1N1-H275Y, conferring 70% or 50% survival at a dosage of 100 mg/kg/d, reducing body weight loss, alleviating the influenza-induced acute lung injury, and reducing lung virus titer. Mechanistic studies showed that SA-2 efficiently inhibited the activity of RNA polymerase and suppressed NP and M1 levels during viral biosynthesis by interfering with gene transcription without having an obvious influence on virus entry and release. Based on these favourable findings, SA-2, a novel anti-influenza agent, with its potent anti-influenza activity in vitro and in vivo, could be a promising antiviral for the treatment of infection of influenza A viruses, including oseltamivir-resistant mutants.

Ribavirin Inhibits Parrot Bornavirus 4 Replication in Cell Culture

Parrot bornavirus 4 is an etiological agent of proventricular dilatation disease, a fatal neurologic and gastrointestinal disease of psittacines and other birds. We tested the ability of ribavirin, an antiviral nucleoside analog with antiviral activity against a range of RNA and DNA viruses, to inhibit parrot bornavirus 4 replication in duck embryonic fibroblast cells. Two analytical methods that evaluate different products of viral replication, indirect immunocytochemistry for viral specific nucleoprotein and qRT-PCR for viral specific phosphoprotein gene mRNA, were used. Ribavirin at concentrations between 2.5 and 25 μg/mL inhibited parrot bornavirus 4 replication, decreasing viral mRNA and viral protein load, in infected duck embryonic fibroblast cells. The addition of guanosine diminished the antiviral activity of ribavirin suggesting that one possible mechanism of action against parrot bornavirus 4 may likely be through inosine monophosphate dehydrogenase inhibition. This study demonstrates parrot bornavirus 4 susceptibility to ribavirin in cell culture.

Antiviral effect of methylated flavonol isorhamnetin against influenza

Influenza is an infectious respiratory disease with frequent seasonal epidemics that causes a high rate of mortality and morbidity in humans, poultry, and animals. Influenza is a serious economic concern due to the costly countermeasures it necessitates. In this study, we compared the antiviral activities of several flavonols and other flavonoids with similar, but distinct, hydroxyl or methyl substitution patterns at the 3, 3′, and 4′ positions of the 15-carbon flavonoid skeleton, and found that the strongest antiviral effect was induced by isorhamnetin. Similar to quercetin and kaempferol, isorhamnetin possesses a hydroxyl group on the C ring, but it has a 3′-methyl group on the B ring that is absent in quercetin and kaempferol. Co-treatment and pre-treatment with isorhamnetin produced a strong antiviral effect against the influenza virus A/PR/08/34(H1N1). However, isorhamnetin showed the most potent antiviral potency when administered after viral exposure (post-treatment method) in vitro. Isorhamnetin treatment reduced virus-induced ROS generation and blocked cytoplasmic lysosome acidification and the lipidation of microtubule associated protein1 light chain 3-B (LC3B). Oral administration of isorhamnetin in mice infected with the influenza A virus significantly decreased lung virus titer by 2 folds, increased the survival rate which ranged from 70–80%, and decreased body weight loss by 25%. In addition, isorhamnetin decreased the virus titer in ovo using embryonated chicken eggs. The structure-activity relationship (SAR) of isorhamnetin could explain its strong anti-influenza virus potency; the methyl group located on the B ring of isorhamnetin may contribute to its strong antiviral potency against influenza virus in comparison with other flavonoids.

Baicalin and baicalein inhibit transforming growth factor-β1-mediated epithelial-mesenchymal transition in human breast epithelial cells

Since the epithelial-mesenchymal transition (EMT) is involved in many crucial functions of cancer cells, we set out to identify a natural compound capable of inhibiting EMT processes. TGF-β1 treatment induces EMT among normal mammary epithelial cells (MCF10A cells), as reflected by characteristic morphological changes into the fibroblastic phenotype, reduced expression of E-cadherin. Interestingly, butanol extracts of Scutellaria baicalensis Georgi significantly reduced the TGF-β1-mediated EMT of MCF10A cells. Further analysis revealed that baicalin and baicalein, the major flavones of these butanol extracts, inhibited TGF-β1-mediated EMT by reducing the expression level of the EMT-related transcription factor, Slug via the NF-κB pathway, and subsequently increased migration in MCF10A cells. Finally, both compounds reduced the TGF-β1-mediated EMT, anchorage-independent growth and cell migration of human breast cancer cells (MDA-MB-231 cells). Taken together, these results suggest that baicalin and baicalein of Scutellaria baicalensis Georgi may suppress the EMT of breast epithelial cells and the tumorigenic activity of breast cancer cells. Thus, these compounds could have potential as therapeutic or supplementary agents for the treatment of breast cancer.

Baicalein Triggers Autophagy and Inhibits the Protein Kinase B/Mammalian Target of Rapamycin Pathway in Hepatocellular Carcinoma HepG2 Cells

Baicalein (BA), isolated from the Chinese medicinal herb Scutellariae radix (Huangqin in Chinese), is a flavonoid with various pharmacological effects. Herein, we found that BA only slightly reduced the cell viability on HepG2 cells after 24-h treatment as determined by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. However, BA (50 μM) effectively blocked the colony formation. Meanwhile, BA remarkably induced the formation of autophagosomes after 24-h treatment as determined by immunofluorescence with monodansylcadaverine staining as well as transmission electron microscopy, respectively. Moreover, BA obviously up-regulated the expression of microtubule-associated protein 1A/1B-light chain 3-II in concentration-dependent and time-dependent manners in HepG2 cells. When combined with the autophagy inhibitor chloroquine and BA, the cell viability and colony formation were significantly decreased, indicating that BA triggered protective autophagy, which prevented cell death. Further study showed that BA concentration-dependently and time-dependently decreased the expression of p-AKT (S473), p-ULK1 (S757) and p-4EBP1 (T37 and S65), suggesting the involvement of protein kinase B (AKT)/mammalian target of rapamycin (mTOR) in BA-triggered autophagy.

Antiviral activity of baicalin against influenza A (H1N1/H3N2) virus in cell culture and in mice and its inhibition of neuraminidase

Scutellaria baicalensis Georgi, a Chinese herbal decoction, has been used for the treatment of the common cold, fever and influenza virus infections. In previous studies, we found that oral administration of baicalein resulted in the inhibition of influenza A virus replication in vivo, which was linked to baicalin in serum. However, the effective dose and underlying mechanisms of the efficacy of baicalin against influenza A virus have not been fully elucidated. In this study, the antiviral effects of baicalin in influenza-virus-infected MDCK cells and mice were examined. The neuraminidase inhibition assay was performed to investigate the mechanism of action of baicalin. In vitro results showed that baicalin exhibited a half-maximal effective concentration (EC50) of 43.3 μg/ml against the influenza A/FM1/1/47 (H1N1) virus and 104.9 μg/ml against the influenza A/Beijing/32/92 (H3N2) virus. When added to MDCK cell cultures after inoculation with influenza virus, baicalin demonstrated obvious antiviral activity that increased in a dose-dependent manner, indicating that baicalin affected virus budding. Baicalin had clear inhibitory effects against neuraminidases, with half-maximal inhibitory concentration (IC50) of 52.3 μg/ml against the influenza A/FM1/1/47 (H1N1) virus and 85.8 μg/ml against the influenza A/Beijing/32/92 (H3N2) virus. In vivo studies showed that an intravenous injection of baicalin effectively reduced the death rate, prolonged the mean day to death (MDD) and improved the lung parameters of mice infected with influenza A virus. These results demonstrate that baicalin acts as a neuraminidase inhibitor, with clear inhibitory activities that are effective against different strains of influenza A virus in both cell culture and a mouse model, and that baicalin has potential utility in the management of influenza virus infections.

Effects of flavonoid-induced oxidative stress on anti-H5N1 influenza a virus activity exerted by baicalein and biochanin A

Background

Different flavonoids are known to interfere with influenza A virus replication. Recently, we showed that the structurally similar flavonoids baicalein and biochanin A inhibit highly pathogenic avian H5N1 influenza A virus replication by different mechanisms in A549 lung cells. Here, we investigated the effects of both compounds on H5N1-induced reactive oxygen species (ROS) formation and the role of ROS formation during H5N1 replication.

Findings

Baicalein and biochanin A enhanced H5N1-induced ROS formation in A549 cells and primary human monocyte-derived macrophages. Suppression of ROS formation induced by baicalein and biochanin A using the antioxidant N-acetyl-L-cysteine strongly increased the anti-H5N1 activity of both compounds in A549 cells but not in macrophages.

Conclusions

These findings emphasise that flavonoids induce complex pharmacological actions some of which may interfere with H5N1 replication while others may support H5N1 replication. A more detailed understanding of these actions and the underlying structure-activity relationships is needed to design agents with optimised anti-H5N1 activity.