Antiviral activities of hypericin.

Hypericin, a photodynamic plant quinone, readily inactivated murine cytomegalovirus (MCMV), Sindbis virus, and human immunodeficiency virus type 1 (HIV-1), especially on exposure to fluorescent light. Sindbis virus was significantly more sensitive than MCMV. The inactivated MCMV, when used to infect cells, was incapable of synthesizing early or late viral antigens. In addition to this direct virucidal effect, when hypericin was added to cells infected with viable MCMV, inhibition was also observed, particularly when the compound was added in the first two hours of infection. Again the antiviral effect was augmented by visible light. At effective antiviral concentrations, there were no discernible adverse effects on cultured cells. Thus hypericin appears to have two modes of antiviral activity: one directed at the virions, possibly on membrane components (although other virion targets cannot be ruled out), and the other directed at virus-infected cells. Both activities are substantially enhanced by light. Other recent studies on the antiviral activities of hypericin have not considered the role of light, and it is conceivable that apparent discrepancies between their results may have reflected different conditions of light exposure.     

Antiviral activities of lactoferrin.

Lactoferrin (LF) is an iron binding glycoprotein that is present in several mucosal secretions. Many biological functions have been ascribed to LF. One of the functions of LF is the transport of metals, but LF is also an important component of the non-specific immune system, since LF has antimicrobial properties against bacteria, fungi and several viruses. This review gives an overview of the present knowledge about the antiviral activities and, when possible, the antiviral modes of action of this protein. Lactoferrin displays antiviral activity against both DNA- and RNA-viruses, including rotavirus, respiratory syncytial virus, herpes viruses and HIV. The antiviral effect of LF lies in the early phase of infection. Lactoferrin prevents entry of virus in the host cell, either by blocking cellular receptors, or by direct binding to the virus particles.     

环己酰亚胺及其衍生物的抗病毒活性研究

环己酰亚胺能抑制大多真核细胞的蛋白合成, 常作为生化研究试剂被广泛使用。本文对其抗病毒活性进行了较系统研究, 结果显示, 环己酰亚胺体外对人类免疫缺陷病毒、流感病毒、柯萨奇病毒、肠道病毒、单纯疱疹病毒及人巨细胞病毒等多种RNA病毒和DNA病毒显示出很强的抑制作用。尤其是对目前临床上尚缺乏有效治疗药物的柯萨奇病毒B及肠道病毒EV71的强抑制作用令人关注。本文对环己酰亚胺的结构修饰及其构效关系进行了初步探讨, 环己酰亚胺分子结构中的C-2' 羟基和C-2' 羰基为抗病毒活性必需基团, 对C-2' 羟基和C-2' 羰基的修饰均导致其抗病毒活性的降低或消失。     

Antiviral activities in plants endemic to madagascar

In order to determine the potential of Malagasy plants as sources of antiviral activities, ethanolic extracts of 11 plants, endemic to Madagascar, were evaluated for antiviral activities. Nine of the extracts had significant activity against herpes simplex virus (HSV), whereas only four were active against Sindbis virus. Five extracts: Cynometra cloiselii , Cynometra madagascariensis , Evonymopsis longipes , Ravensara retusa , and Terminalia monoceros were particularly potent and could completely inactivate the HSV test inoculum (100 infectious virus particles) at concentrations of less than 25 μg/ml. Most of the active phytochemicals were photosensitizers. However, the combined properties of the active extracts indicated the presence of distinct compounds in different species. On the basis of these results we believe that it would be worthwhile expanding these studies to include additional species of Malagasy plants.     

Antiviral and antimicrobial activities of new nitrobutane derivatives

It is known that some addition products of beta-nitrostyrenes exhibit potent antimicrobial activity. In order to investigate the effects of structural modifications on the biological properties, some new Michael type addition products of beta-ethyl-beta-nitrostyrenes were synthesized. In this study, eight new 1-[(2-aminophenyl)thio]-1-phenyl-2-nitrobutane (2) derivatives were synthesized by addition of 2-aminothiophenol to the double bond of beta-ethyl-beta-nitrostyrenes (1). The chemical structures were proved by IR and 1H-NMR data and by elemental analysis. Antimicrobial activities of the synthesized compound were investigated against Escherichia coil, Pseudomonas aeruginosa, Proteus mirabilis, Enterococcus faecalis, Bacillus subtilis, Staphylococcus aureus, Candida albicans by the microdilution method. In addition, the newly synthesized compounds were studied for antiviral activities. All of them were found to be almost 100 fold more active than the standard compound aciclovir (CAS 59277-89-3).     

Antiviral activities in extracts of Turkish medicinal plants

A total of 16 ethanol extracts of Turkish medicinal plants were evaluated for antiviral activities against herpes simplex virus (HSV) and Sindbis virus (SINV). Extracts of Galanthus elwesii and Rheum ribes showed the most potent anti-HSV activities, while six other extracts had weaker activities. Galanthus elwesii and Leucojum aestivum were the most potent anti-SINV extracts with four others showing weaker activities. In total, five extracts were active against both viruses, three were selective for HSV and one was selective for SINV. Evidence for an antiviral photosensitizer was obtained in two anti-HSV extracts, in which activity was either completely dependent on light, or was con-siderably enhanced by light. Thus, several Turkish medicinal plants appear to be promising sources of antiviral activities.     

Antiviral activities of diarylheptanoids against influenza virus in vitro

The anti-influenza A/PR/8/34 (H1N1) virus activities of ten diarylheptanoids isolated from Alpinia officinarum were examined using the MTT method. The 50% inhibitory concentration of each diarylheptanoid examined was clearly lower than its 50% cytotoxic concentration determined by the MTT assay and/or maximum non-cytotoxic concentration (MNCC) determined by the morphological change of cells. In particular, the influenza virus was more susceptible to 7-(4″-hydroxy-3″-methoxyphenyl)-1-phenyl-4E-hepten-3-one (3) and (5S)-5-hydroxy-7-(4″-hydroxyphenyl)-1-phenyl-3-heptanone (8) than the other diarylheptanoids. Thus, all diarylheptanoids exhibited potential antiviral activity against influenza virus in vitro.     

Antiviral activities of coffee extracts in vitro

Both hot water extracts of coffee grinds and instant coffee solutions inhibited the multiplication of herpes simplex virus type 1, a representative enveloped DNA virus, when they were added to the culture medium of the virus-infected cells at a dose of one fifth the concentration suitable for drinking. The antiherpetic activity was independent of the suppliers (companies) of the coffee grinds and of the locations where the coffee beans were produced. Further characterization revealed that there are two different mechanisms, by which the coffee extracts exert inhibitory activities on the virus infection; (1) a direct inactivation of the infectivity of virus particle (i.e., a virucidal activity) and (2) the inhibition of progeny infectious virus formation at the late stage of viral multiplication in the infected cells. Caffeine, but not quinic acid and chlorogenic acid, inhibited the virus multiplication to some extent, but none of them showed the virucidal activity, suggesting that other component(s) in the coffee extracts must play a role in the observed antiviral activity. In addition, the coffee extracts inhibited the multiplication of poliovirus, a non-enveloped RNA virus, but showed no virucidal effect on this virus.     

Antiviral activities of extracts and selected pure constituents of Ocimum basilicum

1. Ocimum basilicum (OB), also known as sweet basil, is a well known medicinal herb in traditional Chinese medicine preparations. In the present study, extracts and purified components of OB were used to identify possible antiviral activities against DNA viruses (herpes viruses (HSV), adenoviruses (ADV) and hepatitis B virus) and RNA viruses (coxsackievirus B1 (CVB1) and enterovirus 71 (EV71)). 2. The results show that crude aqueous and ethanolic extracts of OB and selected purified components, namely apigenin, linalool and ursolic acid, exhibit a broad spectrum of antiviral activity. Of these compounds, ursolic acid showed the strongest activity against HSV-1 (EC50 = 6.6 mg/L; selectivity index (SI) = 15.2), ADV-8 (EC50 = 4.2 mg/L; SI = 23.8), CVB1 (EC50 = 0.4 mg/L; SI = 251.3) and EV71 (EC50 = 0.5 mg/L; SI = 201), whereas apigenin showed the highest activity against HSV-2 (EC50 = 9.7 mg/L; SI = 6.2), ADV-3 (EC50 = 11.1 mg/L; SI = 5.4), hepatitis B surface antigen (EC50 = 7.1 mg/L; SI = 2.3) and hepatitis B e antigen (EC50 = 12.8 mg/L; SI = 1.3) and linalool showed strongest activity against AVD-II (EC50 = 16.9 mg/L; SI = 10.5). 3. No activity was noted for carvone, cineole, beta-caryophyllene, farnesol, fenchone, geraniol, beta-myrcene and alpha-thujone. 4. The action of ursolic acid against CVB1 and EV71 was found to occur during the infection process and the replication phase. 5. With SI values greater than 200, the potential use of ursolic acid for treating infection with CVB1 and EV71 merits further investigation.     

New cytotoxic biflavonoids from Selaginella delicatula

Five new biflavonoids, robustaflavone 7,4',4'-trimethyl ether, robustaflavone 4',4'-dimethyl ether, 2,3-dihydroamentoflavone 7,4',7'-trimethyl ether, 2,3-dihydroamentoflavone 7,4'-dimethyl ether, and 2',3'-dihydroisocryptomerin 7-methyl ether, together with six known compounds have been isolated from the aerial parts of Selaginella delicatula. The structures of these new compounds were determined through spectral analyses. Among the isolates, robustaflavone 4',4'-dimethyl ether, 2,3-dihydroamentoflavone 7,4'-dimethyl ether, and alpha-tocopheryl quinone exhibited cytotoxicities (ED50 values < 4 microg/mL) against P-388 and/or HT-29 cell lines in vitro.     

Antiviral activities of phosphonoformate sodium to pseudorabies herpesvirus infection in vitro

Context: Phosphonoformate sodium (PFS) has been used as an anti-herpesvirus drug; nevertheless, studies of the use of PFS for treatment of pseudorabies herpesvirus (PrV) infection in the veterinary setting have not been widely reported.

Objective: The present study aimed to analyze the inhibitory effect of PFS on cell infection and apoptosis induced by PrV.

Materials and methods: The infectivity of PrV was determined by plaque assays when PFS was applied to the virus, to the virus-infected cells, and to the cells prior to infection. PCR amplifying DNA polymerase, gE, gG, and gD genes of PrV was performed. PrV-induced cell apoptosis was analyzed by immunofluorescence and flow cytometry.

Results: PFS inhibits cell infection by PrV. Addition of the drug decreased the number of apoptotic cells. Amplification of DNA polymerase and other viral structural genes detected in this study by PCR was reduced, because there were fewer viral DNA copies being made in the presence of the drug. The drug has an inhibitory effect on cell apoptosis induced by PrV.

Discussion and conclusion: PFS has inhibitory effects on cell infection by PrV, which may be used as an anti-PrV agent or combined with other anti-PrV agents. PrV-induced cell apoptotic cells and viral DNA copies decreased in the presence of the PFS.     

New biflavonoids from dragon's blood of Dracaena cinnabari

The new biflavonoids 2'-methoxysocotrin-5'-ol, socotrin-4'-ol, and homoisosocotrin-4'-ol were isolated from dragon's blood of Dracaena cinnabari and their structures elucidated mainly by NMR spectroscopy.     

Antimalarial activity of biflavonoids from Ochna integerrima

During the screening of antimalarial substances, the 80% EtOH extract from the outer bark of Ochna integerrima Merr. (Ochnaceae) was shown to have a good anti-malarial activity (IC50 value: 6.5 microg/mL) whereas extracts from the inner barks of O.integerrima showed no antimalarial activity. Biflavanone (1), which had not been found previously from a natural plant source, was isolated as a potent antimalarial active ingredient (IC50 value: 80 ng/mL) from the extract of the outer barks. The stereoisomer of 1 ( = compound 2) was also isolated from this plant; however, its activity was significantly lower than that of 1.