Mechanism by which ma-xing-shi-gan-tang inhibits the entry of influenza virus

Ethnopharmacological relevance

Ma-xing-shi-gan-tang (MXSGT, aka maxing shigan powder), a Chinese herbal decoction, has been used for the treatment of the common cold, fever, and influenza virus infections. However, the underlying mechanisms of its activity against the influenza virus are not fully understood. In this study, we examined the antiviral effects of MXSGT in influenza-virus-infected MDCK cells and their underlying mechanisms, including the damage of the viral surface ultrastructure and the consequent inhibition of viral entry.

Materials and methods

The antiviral activity of nontoxic concentrations of MXSGT against influenza virus A/WSN/33 was examined by assaying (neutralization assay) its inhibition of the virus-induced cytopathic effects. The mode of MXSGT action was first examined with a time-of-addition assay of synchronized infections, followed by viral attachment and penetration assays. Viral endocytosis was evaluated with attachment and penetration assays. We also performed assays related to the inhibition of viral entry, such as neuraminidase activity, hemagglutinin activity, and phosphoinositide-3-kinase (PI3K)/AKT phosphorylation assays. The inhibition of viral replication was demonstrated by quantitative real-time PCR, immunoblotting, and immunofluorescence microscopy. The surface ultrastructure of the MXSGT-treated virus was revealed by atomic force microscopy.

Results

MXSGT exhibited an EC₅₀ of 0.83±0.41 mg/ml against influenza virus A/WSN/33 (H1N1), with broad-spectrum inhibitory activity against different strains of human influenza A viruses, including clinical oseltamivir-resistant isolates and an H1N1pdm strain. The synthesis of both viral RNA and protein was profoundly inhibited when the cells were treated with MXSGT. The time-of-addition assay demonstrated that MXSGT blocks the virus entry phase. This was confirmed with attachment and penetration assays, in which MXSGT showed similar inhibitory potencies (IC₅₀ of 0.58±0.07 and 0.47±0.08 mg/ml). High-resolution images and quantitative measurements made with atomic force microscopy confirmed that the viral surface structure was disrupted by MXSGT. We also established that viral entry, regulated by the PI3K/AKT signaling pathway, was abolished by MXSGT.

Conclusions

Our results give scientific support to the use of MXSGT in the treatment of influenza virus infections. MXSGT has potential utility in the management of seasonal pandemics of influenza virus infections, like other clinically available drugs.     

Evaluation of the anti-neuraminidase activity of the traditional Chinese medicines and determination of the anti-influenza A virus effects of the neuraminidase inhibitory TCMs in vitro and in vivo

Etnopharmacological relevance

Neuraminidase (NA) inhibitors are currently the most effective drugs to treat influenza A viruses infection. Many traditional Chinese medicines (TCMs) have been used in the clinics to treat influenza. The anti-viral mechanisms of these TCMs and their inhibitory effects towards NA need to be systematically tested.

Aim of the study

To evaluate the anti-NA activity of the TCMs and the anti-influenza A virus effects of the NA inhibitory TCMs in vitro and in vivo.

Material and methods

We tested the inhibitory activity of water extracts from 439 TCMs towards NA. The in vitro anti-influenza virus activities of the 5 TCMs were evaluated using the strain A/California/7/2009 (H1N1) NYMC X-179A of influenza A virus. A randomly selected TCM with NA inhibitory activity, Melia toosendan extract, was further evaluated using a mouse model infected with influenza A virus.

Results

Five TCMs, Duchesnea indica (Andr.) Focke [Fragaria indica Andr.], Liquidambar formosana Hance., Lithospermum erythrorhizon Sieb. et Zucc., Melia toosendan Sieb. et Zucc., and Prunella vulgaris L., exerted potent inhibitory activity towards NA. These TCMs in the range of 25-250 μg/mL had the ability to reduce virus-induced cytopathic effect (CPE) and the virus yield in MDCK cells. Melia toosendan significantly reduced death rate and prolonged mean day to death (MDD) of the viral infected mice.

Conclusions

This study describes five TCMs exerted strong inhibitory activities towards NA, and exhibited antiviral effect against influenza A virus by reducing viral reproduction and reduced CPE of the viral infected cells. Melia toosendan, significantly reduced death rate and prolonged survival of the H1N1 viral infected mice.     

The in vitro antiviral property of Azadirachta indica polysaccharides for poliovirus

Ethnopharmacological relevance

Azadirachta indica A. Juss, popularly known as neem, has been extensively used in Ayurvedic medicine by Indian population for over 2000 years. It is used traditionally for the healing of various diseases. Natural products and their derivatives provide an excellent source for new anti-viral drugs.

Aim of the study

The present study aims at evaluating the activity of two polysaccharides (P1 and P2) isolated from the leaves of Azadirachta indica and their chemical sulfated derivatives (P1S and P2S) against poliovirus type 1 (PV-1).

Materials and methods

The cytotoxicity of the compounds was analyzed by MTT and the antiviral effect was determined by plaque reduction assay in different protocols.

Results

The polysaccharides did not show any cytotoxic effects on HEp-2 cells at the highest tested concentration (200 μg/ml) and exhibited significant antiviral activity with inhibitory concentrations (IC₅₀) of 80 μg/ml, 37.5 μg/ml, 77.5 μg/ml, and 12.1 μg/ml for P1, P1S, P2 and P2S, respectively, and the selectivity indexes (SI) ranged from 18 to 131.9. The compounds demonstrated better inhibitory effect when added concomitantly with the virus infection with a dose-dependent curve inhibition. Lesser effect was observed when the compounds were added after viral infection and the least effect at pre-treatment.

Conclusions

We suggested that the polysaccharides obtained from Azadirachta indica act against PV-1 by inhibiting the initial stage of viral replication. Importantly, original polysaccharides showed better virucidal effect than their sulfated derivatives at all tested concentrations. This study provides a scientific basis for the past and present ethnomedical uses of this plant.     

Xiao-Qing-Long-Tang (Sho-seiryu-to) inhibited cytopathic effect of human respiratory syncytial virus in cell lines of human respiratory tract

Ethnopharmacological relevance

Xiao-Qing-Long-Tang (XQLT, TJ-19, Sho-seiryu-to, so-cheong-ryong-tang) has been used against acute airway diseases for thousands of year in ancient China. Most of the acute airway illnesses are caused by virus. However, without activity against influenza virus, XQLT has been questioned to manage respiratory tract viral infection. Nevertheless, XQLT might be active against airway viruses other than influenza. Human respiratory syncytial virus (HRSV) is one of the most common respiratory viral pathogens without effective management. However, it is unknown whether XQLT has anti-HRSV activity.

Aim of the study

We tested the hypothesis that XQLT can effectively minimize HRSV-induced plaque formation in respiratory tract mucosal cell lines.

Materials and methods

Anti-HRSV activity of a hot water extract of XQLT was examined by plaque reduction assay in both human upper (HEp-2) and low (A549) respiratory tract cell lines. Its effects on syncytial formation and viral fusion (F) protein were examined directly by microscopy and by western blot, respectively. Ability of XQLT to stimulate IFN-β was evaluated by enzyme-linked immunosorbent assay (ELISA).

Results

Hot water extract of XQLT dose-dependently inhibited HRSV-induced plaque formation in both HEp-2 and A549 cells (P<0.0001), particularly when given before viral inoculation (p<0.0001). XQLT inhibited viral attachment (p<0.0001) and internalization (p<0.0001). 300 μg/ml XQLT could decrease both the number and the size of HRSV-induced syncytium without clear effect on the production of viral F protein. XQLT could stimulate epithelial cells to secrete IFN-β before and after viral inoculation to counteract viral infection (p<0.0001).

Conclusions

XQLT is effective against HRSV infection on airway epithelia by preventing viral attachment, internalization, syncytial formation, and by stimulating interferon secretion.     

Jiawei-Yupingfeng-Tang,a Chinese herbal formula,inhibits respiratory viral infections in vitro and in vivo

Ethnopharmacological relevance

Jiawei-Yupingfeng-Tang (JYT) is a Chinese herbal formula that is widely used to treat respiratory tract illness. However, the effect of JYT on respiratory viruses remains unknown. The influenza virus (IFV) and the human respiratory syncytial virus (HRSV) cause millions of cases of severe illness per year, and many of these illnesses develop into lethal pneumonia. The aim of this study is to evaluate whether JYT can be used to treat these infections.

Materials and methods

The effect of JYT against IFV and HRSV was tested using a plaque reduction assay in the lower respiratory tract cell line A549. The expression of ICAM-1 was determined by real-time RT-PCR and western blotting. A mouse model infected with lethal influenza developing into interstitial pneumonia was used to evaluate the effect of JYT in vivo.

Results

JYT extract inhibited both IFV and HRSV in a dose-dependent manner when given before, during and after a viral infection. JYT was effective in blocking the entry of the virus. Furthermore, pre-treatment with JYT reduced the susceptibility of cells to the invasion of HRSV by inhibiting the expression of ICAM-1. Importantly, JYT extract increased the survival rate of lethal influenza-infected mice, prolonged the survival time and alleviated the virus-induced lung lesions, which is comparable with the effects of ribavirin treatment.

Conclusions

These data support JYT as an alternative modality to be used in the treatment of respiratory viral infection induced by HRSV and IFV.     

Proanthocyanidin-enriched extract from Myrothamnus flabellifolia Welw. exerts antiviral activity against herpes simplex virus type 1 by inhibition of viral adsorption and penetration

Aim of the study

Extracts from the aerial parts of the South African resurrection plant Myrothamnus flabellifolia Welw. have been used traditionally against infections of the upper respiratory tract and skin diseases. A polyphenol-enriched extract was investigated for potential antiviral effects against herpes simplex virus type 1 (HSV-1) and adenovirus, and the underlying mode of action was to be studied.

Materials and methods

Antiviral effects of an acetone-water extract (MF) from Myrothamnus flabellifolia on HSV-1 and adenovirus type 3 were tested in infected Vero cells by plaque reduction assay, MTT test and immunofluorescence. The influence of the extract on the HSV-1 envelope glycoprotein D was shown by Western blot. Organotypic full thickness skin models consisting of multilayer skin equivalents were used for the investigation of MF effects on HSV-1 replication.

Results

MF exhibited strong antiviral activity against HSV-1. The HSV-1-specific inhibitory concentration (IC₅₀) was determined as 0.4 μg/mL and the cytotoxic concentration (CC₅₀) against Vero cells as 50 μg/mL. A selectivity index (SI) (ratio of CC₅₀ to IC₅₀) of approximately 120 was calculated when MF was added to the virus inoculum for 1 h at 37 °C prior to infection. The replication of adenovirus 3 was not affected by MF.MF abolished virus entry into the host cell by blocking viral attachment to the cell surface. When added after attachment at a concentration of >6 μg/mL, the extract also inhibited penetration of HSV-1 into the host cell. Polyphenolic compounds from MF directly interacted with viral particles, leading to the oligomerisation of envelope proteins as demonstrated for the essential viral glycoprotein D (gD). Using organotypic full thickness tissue cultures, it was shown that treatment of HSV-1 infected cultures with the MF resulted in reduced viral spread.

Conclusions

A polyphenol-enriched extract from Myrothamnus flabellifolia strongly acts against HSV-1 by blocking viral entry into the cells.     

Anti-influenza virus effects of the aqueous extract from Mosla scabra

Ethnopharmacological relevance

Mosla scabra (Thunb.) C. Y. Wu is a broadly used species in the southeastern China as an antipyretic and antiviral drug for the treatment of colds, fever, inflammation and chronic bronchitis.

Aim of the study

To investigate the anti-influenza virus activities of the aqueous extract from Mosla scabra (AEMS), and to provide evidence for the implication of its immunomodulatory potential for the overall protective effect in lethal murine experimental influenza A infection.

Materials and methods

The anti-influenza virus activities of AEMS or ribavirin were evaluated in embryonated eggs and in a mouse infection model and the effects of AEMS on early immune responses during influenza virus infection were evaluated in a mouse infection model.

Results

At the concentration of 0.3–30.0 mg/ml, AEMS exhibited both preventive and therapeutical effect on embryonated egg. Oral administration of AEMS to mice infected with influenza virus A (IVA) was highly effective in preventing death, inhibiting pneumonia and reducing lung viral titers. It also significantly enhanced IFN-γ, IL-2, IL-4 and IL-5 cytokine-producing splenocytes, increased T-cell subsets like CD4⁺ and CD4⁺/CD8⁺, decreased levels of IL-6 after infection, and provided protective immunity. At a dosage of 4800 mg/kg, almost all treated mice survived, suggesting that AEMS is of low toxicity. However, ribavirin has weaker efficacy compared to AEMS.

Conclusions

These results showed, for the first time, while both AEMS and ribavirin appeared to have similar efficacy against IVA, AEMS playing a role as an immunomodulator and antiviral inhibitor during influenza virus infection, was considered to be less toxic and may warrant further evaluation as a possible agent for the treatment of influenza.     

Cytotoxicity and inhibition of P-glycoprotein by selected medicinal plants from Thailand

Ethnopharmacological relevance

Thai medicine has a long tradition of tonifying medicinal plants. In the present investigation, we studied the flower extracts of Jasminum sambac, Mammea siamensis, Mesua ferrea, Michelia alba, Mimusops elengi, and Nelumbo nucifera and speculated that these plants might influence metabolism and substance flow in the body.

Materials and methods

Isolation of porcine brain capillary endothelial cells (PBCECs) as well as multidrug-resistance CEM/ADR5000 leukemia cells, MDA-M;B-231 breast cancer, U-251 brain tumor, and HCT-116 colon cancer cells were used. The calcein-acetoxymethylester (AM) assay was used to measure inhibition of P-glycoprotein transport. XTT and resazurin assays served for measuring cytotoxicity.

Results

The extracts revealed cytotoxicity towards CCRF-CEM leukemia cells to a different extent. The strongest growth inhibition was found for the n-hexane extracts of Mammea siamensis and Mesua ferrea, and the dichloromethane extracts of Mesua ferrea and Michelia alba. The flower extracts also inhibited P-glycoprotein function in porcine brain capillary endothelial cells and CEM/ADR5000 leukemia cells, indicating modulation of the blood–brain barrier and multidrug resistance of tumors. Bioactivity-guided isolation of coumarins from Mammea siamensis flowers revealed considerable cytotoxicity of mammea A/AA, deacetylmammea E/BA and deacetylmammea E/BB towards human MDA-MB-231 breast cancer, U-251 brain tumor, HCT-116 colon cancer, and CCRF-CEM leukemia cells.

Conclusion

The plants analyzed may be valuable in developing novel treatment strategies to overcome the blood–brain barrier and multidrug-resistance in tumor cells mediated by P-glycoprotein.     

Anti-tumor effect of Shu-gan-Liang-Xue decoction in breast cancer is related to the inhibition of aromatase and steroid sulfatase expression

Ethnopharmacological relevance

Shu-Gan-Liang-Xue Decoction (SGLXD), a traditional Chinese herbal formula used to ameliorate the hot flushes in breast cancer patients, was reported to have anti-tumor effect on breast cancer. Estrogen plays a critical role in the genesis and evolution of breast cancer. Aromatase and steroid sulfatase (STS) are key estrogen synthesis enzymes that predominantly contribute to the high local hormone concentrations. The present study was to evaluate the anti-tumor effect of SGLXD on estrogen receptor (ER) positive breast cancer cell line ZR-75-1, and to investigate its underlying mechanisms both in vitro and in vivo.

Materials and methods

The anti-tumor activity of SGLXD in vitro was investigated using the MTT assay. The in vivo anti-tumor effect of SGLXD was evaluated in non-ovariectomized and ovariectomized athymic nude mice. The effect of SGLXD on enzymatic activity of aromatase and STS was examined using the dual-luciferase reporter (DLR) based on bioluminescent measurements. Aromatase and STS protein level were assessed using Western blot assay.

Results

SGLXD showed dose-dependent inhibitory effect on the proliferation of ZR-75-1 cells with IC₅₀ value of 3.40 mg/mL. It also suppressed the stimulating effect on cell proliferation of testosterone and estrogen sulfates (E₁S). Oral administration of 6 g/kg of SGLXD for 25 days resulted in a reduction in tumor volume in non-ovariectomized and ovariectomized nude mice. The bioluminescent measurements confirmed that SGLXD has a dual-inhibitory effect on the activity of aromatase and STS. Western blot assay demonstrated that the treatment of SGLXD resulted in a decrease in aromatase and STS protein levels both in vitro and in vivo.

Conclusion

Our results suggested that SGLXD showed anti-tumor effect on breast cancer cells both in vitro and in vivo. The anti-tumor activity of SGLXD is related to inhibition of aromatase and STS via decreasing their expression. SGLXD may be considered as a novel treatment for ER positive breast cancer.     

Anti-HIV-1 activities of compounds isolated from the medicinal plant Rhus chinensis

Aim of the study

Previously, we reported that the petroleum ether fraction, RC-1, and EtOAc fraction, RC-2, of the medicinal plant Rhus chinensis showed potent anti-HIV-1 activities. To address anti-HIV-1 constituents of RC-1 and RC-2, 17 compounds were isolated. Anti-HIV-1 activities and possible action mechanisms of these compounds were investigated.

Methods

The syncytial formation induced by HIV-1 was determined under the inverted microscope, cellular toxicity and protection assay were assessed by MTT method, reduction of p24 antigen expression level and RT activity were measured by ELISA, and inhibition of recombinant HIV-1 PR was monitored by the fluorescent signal.

Results

The compounds 1 and 13 inhibited HIV-1-induced syncytium formation potently with TI value of 42.31 and 19.07, respectively. Compounds 4, 5, 6, 9 and 10 were less potent with TI value of 8.94, 8.22, 4.14, 5.11 and 5.34, respectively. Compound 1, a benzofuranone-type compound, previously reported as a novel anti-HIV-1 agent, might target late-steps of HIV-1 life cycle. Compound 13 inhibited HIV-1 replication with EC₅₀ of 7.16 μg/ml and might target at/before integration step.

Conclusion

These compounds might contribute to anti-HIV-1 activities extracts of the medicinal plant Rhus chinensis.     

Fresh ginger (Zingiber officinale) has anti-viral activity against human respiratory syncytial virus in human respiratory tract cell lines

Ethnopharmacological relevance

Ginger, Zingiber officinale Roscoe, is a common spice and also a widely used medicinal plant in ancient China. Ginger is an ingredient of Ge-Gen-Tang (Kakkon-to; GGT). GGT has been proved to have antiviral activity against human respiratory syncytial virus (HRSV). However, it is unknown whether ginger is effective against HRSV.

Aim of the study

To find a readily available agent to manage HRSV infection, the authors tested the hypothesis that ginger can effectively decrease HRSV-induced plaque formation in respiratory mucosal cell lines.

Materials and methods

Effect of hot water extracts of fresh and dried gingers on HRSV was tested by plaque reduction assay in both human upper (HEp-2) and low (A549) respiratory tract cell lines. Ability of ginger to stimulate anti-viral cytokines was evaluated by enzyme-linked immunosorbent assay (ELISA).

Results

Fresh ginger dose-dependently inhibited HRSV-induced plaque formation in both HEp-2 and A549 cell lines (p<0.0001). In contrast, dried ginger didn't show any dose-dependent inhibition. 300 μg/ml fresh ginger could decrease the plaque counts to 19.7% (A549) and 27.0% (HEp-2) of that of the control group. Fresh ginger was more effective when given before viral inoculation (p<0.0001), particularly on A549 cells. 300 μg/ml fresh ginger could decrease the plaque formation to 12.9% when given before viral inoculation. Fresh ginger dose-dependently inhibited viral attachment (p<0.0001) and internalization (p<0.0001). Fresh ginger of high concentration could stimulate mucosal cells to secrete IFN-β that possibly contributed to counteracting viral infection.

Conclusions

Fresh, but not dried, ginger is effective against HRSV-induced plaque formation on airway epithelium by blocking viral attachment and internalization.     

Chemopreventive action of Lygodium flexuosum extract in human hepatoma PLC/PRF/5 and Hep 3B cells

Ethnopharmacological relevance

Lygodium flexuosum (Lygodiaceae), a medicinal fern used in Indian traditional medicine against liver disorders.

Aim of the study

The rationale of the study was to examine whether the n-hexane extract from plant Lygodium flexuosum affects apoptosis on human hepatoma PLC/PRF/5 and Hep 3B cells.

Materials and methods

Chemopreventive activity of the Lygodium flexuosum extract was determined by MTT assay, annexin-V FITC binding to phosphatidyl serine and cleavage of PARP. Subdiploid condition of cells treated with Lygodium flexuosum was analyzed by flow cytometry. Further, used transiently transfected NF-κB reporter in PLC/PRF/5 cells to evaluate the inhibitive effect of Lygodium flexuosum extract.

Results

Lygodium flexuosum extract inhibited the cell viability and induced apoptosis in hepatoma cells in a concentration dependent manner as evidenced by apoptotic changes such as flipping of phosphatidyl serine, cleavage of PARP. Cell cycle analysis showed the subG1 apoptotic population in cells treated with higher concentrations of the extract. When activated with exogenous TNF-α in transfected hepatoma cells it was observed that NF-κB dependent gene expression was inhibited by treatment with Lygodium flexuosum extract in PLC/PRF/5 cells dose-dependently.

Conclusions

This investigation suggests that the Lygodium flexuosum extract has antiproliferative and apoptotic activity in both cancer cells and has inhibitive role in TNF-α induced NF-κB activation in PLC/PRF/5 cells confirms the potential of the extract as a chemopreventive agent.     

Identification of antihyperlipidemic constituents from the roots of Rubia yunnanensis Diels

Ethnopharmacological relevance

The roots of Rubia yunnanensis Diels (Rubiaceae) have been used as an alternative for Rubia cordifolia for the treatment of various diseases including cardiovascular disease and metabolic disease for a long history in traditional Chinese medicine. To evaluate antihyperlipidemic activity of the roots of Rubia. yunnanensis Diels and to identify active compounds from the active fraction.

Material and methods

Antihyperlipidemic effects of extract and compounds of the roots of Rubia yunnanensis were studied in HepG2 cells and in vivo model in olive oil-loaded mice. The isolation of compounds was conducted using various chromatographic methods and the structures of the isolated compounds were elucidated by NMR and MS techniques.

Results

Methanol extract and ethyl acetate fraction of Rubia yunnanensis potently decreased the triglycerides accumulation in HepG2 cells and the methanol extract of Rubia yunnanensis (125, 250 and 500 mg/kg) significantly inhibited the TG elevation in a dose dependent manner in olive oil-loaded mice. Through various chromatographic methods, twenty-three compounds (1–23) were isolated in which arborinane-type triterpenoids and a free anthraquinone potently inhibited TG levels in HepG2 cells.

Conclusion

Arborinane-type triterpenoids, especial rubiarbonone C (16) and an anthraquinone, 2-methyl-1, 3, 6-trihydroxy-9, 10-anthraquinone (MTHA) (22) were identified as the main active compounds responsible for antihyperlipidemic activity. Based on these findings, we proposed that the extract of Rubia yunnanensis and its active components, arborinane-type triterpenoids and the free anthraquinone might be beneficial in the treatment and prevention of hyperlipidemic disease.     

Ge-Gen-Tang has anti-viral activity against human respiratory syncytial virus in human respiratory tract cell lines

Ethnopharmacological relevance

Ge-Gen-Tang (GGT) has been used against adult respiratory tract infection for thousand years in ancient China. However, GGT is unable to inhibit influenza virus. The effect of GGT to manage respiratory tract viral infection has been questioned. Several ingredients of GGT and their constituents are able to inhibit various viruses. Therefore, GGT might have antiviral activity against other viruses causing respiratory tract illness. Human respiratory syncytial virus (HRSV) is one of the most important airway viruses. However, it is unknown whether GGT is effective against HRSV.

Aim of the study

HRSV contributes considerably to respiratory tract illness of the elderly and immunocompromised adults. There is no effective therapeutic modality for HRSV infection. In order to find a readily available agent to manage HRSV infection, the authors tested the hypothesis that GGT can effectively minimize airway pathology by preventing HRSV-induced plaque formation in respiratory mucosal cell lines.

Materials and methods

Effect of the hot water extract of GGT on HRSV was tested by plaque reduction assay in both human upper (HEp-2) and low (A549) respiratory tract cell lines. Ability of GGT to stimulate anti-viral cytokines was evaluated by enzyme-linked immunosorbent assay (ELISA).

Results

GGT dose-dependently inhibited HRSV-induced plaque formation in both cell lines (p < 0.0001), especially in A549 cells. GGT was more effective when given before viral infection (p < 0.0001). GGT could dose-dependently inhibit viral attachment (p < 0.0001) with or without heparin. GGT could further inhibit HRSV internalization time-dependently and dose-dependently (p < 0.0001). GGT could stimulate mucosal cells to secrete IFN-β to counteract viral infection before and after viral inoculation.

Conclusions

GGT is effective against HRSV-induced plaque formation in airway epithelium.     

In vitro antiprotozoal and cytotoxic activity of 33 ethonopharmacologically selected medicinal plants from Democratic Republic of Congo

Ethnopharmacological relevance

The antiprotozoal and cytotoxic activity of the aqueous extracts from 33 medicinal plants, used by traditional healers for the treatment of various parasitic diseases and collected after an ethnopharmacological inventory conducted in the Bolongo area, Bandundu province in DR Congo, was evaluated.

Materials and methods

Decoctions were prepared, lyophilized and evaluated for in vitro antiprotozoal activity against Trypanosoma b. brucei, Trypanosoma cruzi, Leishmania infantum, and the chloroquine- and pyrimethamine-resistant K1 strain of Plasmodium falciparum. Cytotoxicity against MRC-5 cells was included to assess selectivity of activity.

Results

Most of the tested extracts exhibited pronounced (IC₅₀ ≤ 5 μg/ml) or good (5 < IC₅₀ ≤ 10 μg/ml) antiprotozoal activity against one or more of the selected protozoa. A total of 19 plant extracts inhibited Trypanosoma b. brucei, especially the extract from Isolona hexaloba stem bark (IC₅₀ = 1.95 μg/ml, SI = 16.5); 8 plant extracts were active against Trypanosoma cruzi, the extracts from Enanatia chlorantha stem bark and Quassia africana root bark being the most active with IC₅₀ values of 1.87 and 1.88 μg/ml, respectively (SI = 3.0 and 3.3, respectively); 8 plant extracts showed activity against Leishmania infantum, with extracts from Napoleona vogelii stem bark and Quassia africana root bark as the most active with IC₅₀ values of 5.66 and 5.04 μg/ml (SI = 11.3 and 1.2). Finally, 9 plant extracts inhibited Plasmodium falciparum K1 with the extracts from Quassia africana (root bark and stem bark) being the most active ones with IC₅₀ values of 0.46 and 1.27 μg/ml (SI = 13.7 and 13.6). Extracts from Enantia chlorantha stem bark, Piptadeniastrum africanum stem bark and Quassia africana root bark were cytotoxic for MRC-5 cells (CC₅₀ < 10 μg/ml).

Conclusions

These results can partly support and justify the traditional use of some of these plant species for the treatment of parasitic diseases.