Specific down-regulation of spinal μ-opioid receptor and reduced analgesic effects of morphine in mice with postherpetic pain

The analgesic effects of opioid agonists and the expression of μ-and κ-opioid receptors were compared between mice with herpetic pain and those with postherpetic pain induced by herpetic virus inoculation. Morphine inhibited herpetic pain more effectively than postherpetic pain. Intrathecal injection reduced the analgesic effects of morphine on postherpetic pain, but intracerebroventricular injection did not. The κ-opioid receptor agonist nalfurafine suppressed herpetic and postherpetic pain to similar degrees. μ-Opioid receptor-like immunoreactivities in the lumbar dorsal horn were markedly decreased at the postherpetic, but not herpetic, stage of pain. In the dorsal root ganglia, the expression of μ-opioid receptor mRNA was significantly decreased in mice with postherpetic pain, whereas the κ-opioid receptor mRNA level was not altered. These results suggest that specific down-regulation of the μ-opioid receptor in the primary sensory neurons is responsible for the reduced analgesic action of morphine on postherpetic pain. The κ-opioid receptor may be a useful target for the analgesic treatment of postherpetic neuralgia

Characterization of anti-herpes simplex virus type 1 activity of an alkaloid FK 3000 from Stephania cepharantha

A morphinane alkaloid FK 3000 (6,7-di-O-acetylsinococuline) from the root tubers of Stephania cepharantha showed antiviral activity against acyclovir (ACV)- and phosphonoacetic acid (PAA)-resistant herpes simplex virus type 1 (HSV-1), influenza virus, measles virus, and poliovirus. The anti-HSV action of FK 3000 was assessed in comparison with that of PAA that inhibits the activity of HSV DNA polymerase and HSV DNA synthesis. FK 3000 inhibited the growth of thymidine kinase-deficient and ACV and PAA-resistant HSV-1 strains, as well as wild type HSV strains in Vero cells. This compound, as well as PAA, interfered with the synthesis of late viral proteins but not early viral proteins. The analysis of HSV DNA synthesis by slot blot hybridization showed that FK 3000 inhibited the viral DNA synthesis in a dose-dependent manner. However, the viral RNA was partially synthesized in the presence of FK 3000 (even at a dose that HSV DNA synthesis was inhibited) and PAA, indicating that FK 3000, as well as PAA, allowed early viral RNA synthesis but not viral DNA synthesis. Since partially purified HSV DNA polymerase activity was not inhibited by FK 3000, this compound was suggested to inhibit HSV DNA synthesis by a mechanism different from that of PAA. Stephania cepharantha(タマザキツヅラフジ)から得たモルフィン骨格を有するアルカロイドFK3000はacyclovirやphosphonoacetic acid(PAA)抵抗性を有するHSV-1, influenza virs, measles virus, poho virsに対しても抗ウイルス作用を有していた。この抗HSV作用をHSV DNA polymeraseを阻害することによりHSV DNA合成を阻害することが知られているPAAとの比較から検討した。HSVに感染したVero細胞においてFK3000は,PAAと同様に後期ウイルス蛋白の合成を阻害したが初期ウイルス蛋白には影響しなかった。Slot blot hybridization法でHSV DNA合成を調べると,FK3000は濃度依存的にウイルスDNA合成を阻害することが判明した。しかし,ウイルスRNA合成はHSV DNA合成が阻害される濃度でもFK3000およびPAAによって部分的にのみ阻害された。このことはPAAと同様にFK3000はウイルスDNA合成は阻害するが初期ウイルスRNAの合成は許容することを示している。FK3000は粗精製したHSV-DNA polymerase活性を阻害しないことから,PAAと異なった機構でHSV DNA合成を阻害していることが示唆された

Inhibitory activities of Thai medicinal plants against herpes simplex type 1, poliovirus type 1, and measles virus

Forty-eight ethanol- and 43 water-extracts of 49 traditional Thai medicines were evaluated for antiviral activities by a plaque reduction assay. For preliminary characterization of the mode of their antiviral action, poliovirus type 1, measles virus and herpes simplex virus type 1 (HSV-1) that are different in nucleic acid component and enveloped structure were used in this study. Fifty-two, 28 and 29 extracts exhibited inhibitory activities against poliovirus, measles virus and HSV-1, respectively. Of 29 extracts with anti-HSV-1 activities, the inhibitory activities of Rhinacanthus nasutus (leaf), Terminalia citrina (fruit) and Thevetia peruviana (leaf) were observed in both ethanol and water extracts. The ethanol extracts of Derris scandens (leaf) and Plumbago indica (leaf) and the water extract of Capsicum frutescens (fruit) were active against only HSV-1, suggesting the mechanism of their antiviral action likely unique to HSV-1 but neither poliovirus nor measles virus. Contrarily, 26 extracts displayed inhibitory activities against poliovirus and/or measles virus. These findings suggest that the 29 extracts from traditional Thai medicines are potential candidates for anti-HSV agents. 49種のタイ伝統薬物から作製した48のエタノールエキス,43の水エキスに対する抗ウイルス活性をプラーク減少法で検索した。本研究では,核酸やエンベロープ構造の異なるポリオウイルス1型,麻疹ウイルス,単純ヘルペスウイルス1型に対して検討を行なった。その結果ポリオウイルス1型に対しては52種,麻疹ウイルスには28種,単純ヘルペスウイルス1型には29種のエキスが阻害活性を示した。単純ヘルペス1型に有効であった29種の中では,Rhinacanthus nasutus(葉),Terminalia citrina(果実),Thevetia peruviana(葉)はエタノール,水の両エキスで阻害作用を示した。Derris scandens(葉),Plumbago indica(葉)およびCapsicum frutescens(果実)のエタノールエキスは単純ヘルペスウイルス1型にのみ活性があった。このことはポリオウイルスや麻疹ウイルスには無効で,単純ヘルペス1型のみに特異的に有効であることを示唆している。一方,26種のエキスはポリオウイルスあるいは麻疹ウイルス,また両方に有効であった。これらの結果はタイ伝統薬物からの29のエキスが抗ヘルペス剤として有力な候補となることを示している

Efficacy of Brazilian Propolis against Herpes Simplex Virus Type 1 Infection in Mice and Their Modes of Antiherpetic Efficacies

Ethanol extracts (AF-06, 07, and 08, 10 mg/kg) of Brazilian propolis were administered orally to cutaneously herpes simplex virus type 1 (HSV-1)-infected mice three times daily on days 0 to 6 after infection to evaluate their efficacies against HSV-1 infection and significantly limited development of herpetic skin lesions. AF-07 and 08 significantly reduced virus titers in brain and/or skin on day 4 without toxicity, but AF-08 had no anti-HSV-1 activity in vitro. AF-06 and 08 significantly enhanced delayed-type hypersensitivity (DTH) to inactivated HSV-1 antigen in infected mice. Oral AF-08-administration significantly augmented interferon (IFN)-γ production by HSV-1 antigen from splenocytes of HSV-1-infected mice, while direct exposure of splenocytes of infected mice to AF-06 significantly elevated IFN-γ production in vitro. Thus, AF-08 might have components that are active in vivo even after oral administration and those of AF-06 might be active only in vitro. Because DTH is a major host defense for intradermal HSV-1 infection, augmentation of DTH response by AF-06 or 08, directly or indirectly, respectively, may contribute to their efficacies against HSV-1 infection. In addition, AF-06 and 07 possibly contain anti-HSV-1 components contributing to their efficacies. Such biological activities of Brazilian propolis may be useful to analyze its pharmacological actions

New antiviral agents from traditional medicines(Chemical & Pharmacological study)

We summarized the flow of our research on the development of antiviral traditional medicines, which was a collaboration with the late Professor Tsuneo Namba. Even if traditional medicines and compounds purified from them have strong antiviral activity in vitro, we believe they are just inhibitors and not medicines if they have no therapeutic efficacy in vivo. Therefore our study is based on the confirmation of the oral therapeutic efficacy with traditional dosages in humans. We first screened the in vitro-antiviral activity of typically and easily available traditional medicines that are currently used for the treatment of various chronic diseases in China, India and Japan. Then we selected the extracts of traditional medicines with prophylactic and therapeutic antiviral activity in animal infection models. By verifying the antiviral activity of extracts in vivo, their new indications for the use of viral infection would be established. In consequence, the drinking of the extracts of traditional medicines like a daily tea or coffee may be used as prophylaxis and therapy for diseases caused by viral infection and improve the quality of life. Here, we describe how the antiviral extracts of traditional medicines and active compounds involved in them were explored and characterized, based on a view that antiviral activity should be active in vivo