In vivo anti-influenza virus activity of Japanese herbal (kampo) medicine, "shahakusan," and its possible mode of action

Which East Asian herbal medicines can decrease viral infections?

Whilst Western research for the COVID-19 crisis focuses on vaccination, in East Asia traditional herbal prescriptions are studied for SARS-CoV2 therapy. In Japan, Maoto (Ephedrae herba 4 g, Armeniacae semen 4 g, Cinnamomi cortex 3 g, and Glycyrrhizae radix 2 g, JPXVII) is used based on clinical evidence for its effect on early phase influenza (also caused by RNA viruses) comparable to that of oseltamivir. The Health Ministry of Thailand has approved Andrographis paniculata (Jap. Senshinren) extracts for treatment of COVID-19. Its combination (4 g) with Maoto, Maoto-ka-senshinren, seems most promising for the treatment of viral pandemics. In China, the official guideline for COVID-19 treatment contains TCM medications with antiviral, as well as immunmodulatory and anti-inflammatory effects such as: Qing-Fei-Pai-Du-Tang (Jap. Seihai-haidokuto) contains 21 drugs; Shufeng Jiedu Jiaonang (Bupleuri radix 8 g, Forsythiae fructus 8 g, Glycyrrhizae radix 4 g, Isatidis radix 8 g, Patriniae herba 8 g, Phragmitis rhizoma 6 g, Polygoni cuspidati rhizoma 10 g, Verbenae herba 8 g); Fufang Yuxingcao Heiji (Forsythiae fructus 0.6 g, Houttuyniae herba 6 g, Isatidis radix 1.5 g, Lonicerae flos 0.6 g, Scutellariae radix 1.5 g) first gained prominence during the 2002 SARS epidemic. With no Western medicine available, the following overview discusses efficacy and mechanisms in view of viral entry and replication of different East Asian herbal remedies for COVID-19 treatment.

Properties of the Novel Chinese Herbal Medicine Formula Qu Du Qiang Fei I Hao Fang Warrant Further Research to Determine Its Clinical Efficacy in COVID-19 Treatment

Introduction: COVID-19, the infectious disease induced by the virus severe acute respiratory syndrome-related coronavirus-2, has caused increasing global health concerns, and novel strategies to prevent or ameliorate the condition are needed. Traditional Chinese Medicine (TCM) herbal formulas have been used in the treatment of epidemics in China for over 2000 years. This study investigated the therapeutic effects of Qu Du Qiang Fei I Hao Fang (QDQF1) "Eliminating Virus and Strengthening Lung-No.1 Formula," in the treatment and prevention of COVID-19. QDQF1 consists of Shēng Huáng Qí, Běi Shā Shēn, Chuān Jié Gěng, Zhì Fáng Fēng, Qīng Lián Qiáo, Jīn Yín Huā, Bǎn Lán Gēn, Chǎo Cāng Zhú, Zǐ Huā Dì Dīng, and Shēng gān căo. Materials and Methods: A literature survey was performed by conducting systematic electronic searches in PubMed, Science Direct, Google Scholar, and in books. Results: Each herb in this formula has long been used to treat various diseases due to their pharmacologic, antiviral, anti-inflammatory, and antimicrobial effects that inhibit microbial adherence to mucosal or epithelial surfaces, inhibit endotoxin shock, and selectively inhibit microbial growth. Conclusion: The herbs chosen for the QDQF1 formula have been historically paired, and cast a wide net over the potential COVID-19 symptomatology. Their combined functions provide comprehensive and balanced therapeutics from both TCM and allopathic perspectives. Individual herbs and herbal combinations are analyzed for their applicability to pertinent TCM patterns of COVID-19 presentations, including heat and cold patterns, damp and phlegm syndromes, toxicity, and deficiency patterns. A further study in a randomized, double-blind, and placebo-controlled trial of QDQF1 is recommended to assess its therapeutic efficacy in the treatment of COVID-19.

Kampo Medicines for Infectious Diseases

Numerous Kampo medicines and Oriental herbs have been used for the treatment of infectious diseases for several reasons, such as genetic background, economical reasons, fewer adverse effects, and so on. This chapter describes Kampo medicines and related Oriental herbs that are effective or promising in the treatment of infectious diseases at the clinical level and/or in animal models. In addition, effective Kampo medicines tested in vitro in cultured-cell studies are also included in this chapter. Each section is categorized by infectious disease and according to the popularity of the Kampo medicine.

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.

Orally Administered Salacia reticulata Extract Reduces H1N1 Influenza Clinical Symptoms in Murine Lung Tissues Putatively Due to Enhanced Natural Killer Cell Activity

Influenza is a major cause of respiratory tract infection. Although most cases do not require further hospitalization, influenza periodically causes epidemics in humans that can potentially infect and kill millions of people. To countermeasure this threat, new vaccines need to be developed annually to match emerging influenza viral strains with increased resistance to existing vaccines. Thus, there is a need for finding and developing new anti-influenza viral agents as alternatives to current treatments. Here, we tested the antiviral effects of an extract from the stems and roots of Salacia reticulata (SSRE), a plant rich in phytochemicals, such as salacinol, kotalanol, and catechins, on H1N1 influenza virus-infected mice. Following oral administration of 0.6 mg/day of SSRE, the incidence of coughing decreased in 80% of mice, and only one case of severe pulmonary inflammation was detected. Moreover, when compared with mice given Lactobacillus casei JCM1134, a strain previously shown to help increase in vitro natural killer (NK) cell activity, SSRE-administered mice showed greater and equal NK cell activity in splenocytes and pulmonary cells, respectively, at high effector cell:target cell ratios. Next, to test whether or not SSRE would exert protective effects against influenza in the absence of gut microbiota, mice were given antibiotics before being inoculated influenza virus and subsequently administered SSRE. SSRE administration induced an increase in NK cell activity in splenocytes and pulmonary cells at levels similar to those detected in mice not treated with antibiotics. Based on our results, it can be concluded that phytochemicals in the SSRE exerted protective effects against influenza infection putatively via modulation of the immune response, including enhancement of NK cell activity, although some protective effects were not necessarily through modulation of gut microbiota. Further investigation is necessary to elucidate the molecular mechanisms underlying the protective effects of SSRE against influenza infection.

Anti-influenza (H1N1) potential of leaf and stem bark extracts of selected medicinal plants of South India

Variations in antioxidant and anti-viral activities (against Influenza AP/R/8 (H1N1) virus) between the leaves and stem bark of selected medicinal plants were studied. Malin Darby canine kidney (MDCK) cells were used for the viral infection and the antiviral activity of the extracts was studied using sulphorhodamine B (SRB) assay. The stem bark of the plants including Strychnos minor, Diotacanthus albiflorus, Strychnos nux-vomica and Chloroxylon swietenia showed higher flavonoid contents as well as 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) scavenging activity when compared with their leaves. In case of 1,1-diphenyl-2-picrylhydrazyl (DPPH) activity, the stem bark of S. nux-vomica and leaf extract of C. swietenia showed the highest activity. Based on the IC₅₀ values, the stem bark extracts of Cayratia pedata (20.5 μg/mL) and S. minor (22.4 μg/mL) showed high antiviral activity. In the mean-time S. nux-vomica, C. swietenia and C. swietenia bark extracts showed cytotoxicity to the MDCK cells. When comparing the stem bark and leaves the content of gallic acid, ferulic acid, o-coumaric acid, total flavonoids (TFC) and total phenols (TPC) was higher in stem bark and hence their anti-viral activity was high. Further study based on the metabolites against H1N1 can reveal the potential of therapeutic compounds against the viral disease.

Screening of ethnic medicinal plants of South India against influenza (H1N1) and their antioxidant activity

Antiviral activity against H1N1 influenza was studied using ethnic medicinal plants of South India. Results revealed that Wrightia tinctoria (2.25 μg/ml) was one of the best antidotes against H1N1 virus in terms of inhibitory concentration of 50% (IC50) whereas the control drug Oseltamivir showed 6.44 μg/ml. Strychnos minor, Diotacanthus albiflorus and Cayratia pedata showed low cytotoxicity (>100) to the MDCK (Malin darby canine kidney) cells by cytotoxicity concentration of 50% (CC50) and possessed antiviral activity suggesting that these plants can be used as herbal capsules for H1N1 virus. W. tinctoria and S. minor showed high therapeutic indexes (TI) such as 12.67 and 21.97 suggesting that those plants can be used for anti-viral drug development. The CC50 values of Eugenia singampattiana (0.3 μg/ml), Vitex altissima (42 μg/ml), Salacia oblonga (7.32 μg/ml) and Salacia reticulata (7.36 μg/ml) resulted in cytotoxicity of the MDCK cells, due to their high phenolic content. Findings from this study state that the plant W. tinctoria can be a potent source for third generation anti-viral drug development against H1N1.

Alleviative Effects of a Kampo (a Japanese Herbal) Medicine "Maoto (Ma-Huang-Tang)" on the Early Phase of Influenza Virus Infection and Its Possible Mode of Action

A Kampo medicine, maoto, has been prescribed in an early phase of influenza-like illness and used for a treatment of influenza clinically in Japan these days. However, the efficacy of maoto against the virus infection remains to be elucidated. This study was conducted to evaluate the alleviative effects of maoto against early phase of influenza virus infection and its preliminary mode of actions through immune systems. When maoto (0.9 and 1.6 g/kg/day) was orally administered to A/J mice on upper respiratory tract infection of influenza virus A/PR/8/34 from 4 hours to 52 hours postinfection (p.i.) significant antipyretic effect was shown in comparison with water-treated control. Administration of maoto (0.8 and 1.3 g/kg/day) significantly decreased the virus titers in both nasal (NLF) and bronchoalveolar lavage fluids (BALF) at 52 hours p.i., and significantly increased the anti-influenza virus IgM, IgA, and IgG₁ antibody titers in NLF, BALF, and serum, respectively. Maoto also increased significantly the influenza virus-bound IgG₁ and IgM antibody titers in serum and the virus-bound IgM antibody titer in even the BALF of uninfected A/J mice. These results indicate that maoto exerts antipyretic activity in influenza virus-infected mice and virus reducing effect at an early phase of the infection through probably augmentation of the virus-bound natural antibodies.

Identification of traditional medicinal plant extracts with novel anti-influenza activity

The emergence of drug resistant variants of the influenza virus has led to a need to identify novel and effective antiviral agents. As an alternative to synthetic drugs, the consolidation of empirical knowledge with ethnopharmacological evidence of medicinal plants offers a novel platform for the development of antiviral drugs. The aim of this study was to identify plant extracts with proven activity against the influenza virus. Extracts of fifty medicinal plants, originating from the tropical rainforests of Borneo used as herbal medicines by traditional healers to treat flu-like symptoms, were tested against the H1N1 and H3N1 subtypes of the virus. In the initial phase, in vitro micro-inhibition assays along with cytotoxicity screening were performed on MDCK cells. Most plant extracts were found to be minimally cytotoxic, indicating that the compounds linked to an ethnomedical framework were relatively innocuous, and eleven crude extracts exhibited viral inhibition against both the strains. All extracts inhibited the enzymatic activity of viral neuraminidase and four extracts were also shown to act through the hemagglutination inhibition (HI) pathway. Moreover, the samples that acted through both HI and neuraminidase inhibition (NI) evidenced more than 90% reduction in virus adsorption and penetration, thereby indicating potent action in the early stages of viral replication. Concurrent studies involving Receptor Destroying Enzyme treatments of HI extracts indicated the presence of sialic acid-like component(s) that could be responsible for hemagglutination inhibition. The manifestation of both modes of viral inhibition in a single extract suggests that there may be a synergistic effect implicating more than one active component. Overall, our results provide substantive support for the use of Borneo traditional plants as promising sources of novel anti-influenza drug candidates. Furthermore, the pathways involving inhibition of hemagglutination could be a solution to the global occurrence of viral strains resistant to neuraminidase drugs.