Duck hepatitis B virus (DHBV) replication in primary duck hepatocytes was monitored by examining the synthesis of both DHBV DNA and DHBV core antigen. Several nucleoside analogs which were previously shown to inhibit the replication of DNA viruses (i.e., herpesviruses) and retroviruses were examined for their inhibitory effects on the synthesis of DHBV core antigen in primary duck hepatocytes. (S)-9-(3-Hydroxy-2-phosphonylmethoxypropyl)adenine [(S)-HPMPA], 9-(2-phosphonylmethoxyethyl)-2,6-diaminopurine, 2',3'-dideoxyadenosine, and 2',3'-dideoxycytidine inhibited DHBV core antigen synthesis at concentrations that were significantly lower than those found to be toxic to the primary hepatocytes. Of all the compounds tested, (S)-HPMPA showed the lowest 50% effective concentration (0.5 ,ug/ml). The selectivity index or ratio of the 50% cytotoxic concentration to the 50% effective concentration of (S)-HPMPA was greater than 300. (S)-HPMPA not only inhibited DHBV core antigen but also DHBV DNA synthesis in DHBV-infected hepatocytes.Human hepatitis B virus (HBV) is a causative agent of both an acute and chronic form of hepatitis. More than 200 million people worldwide are estimated to be chronic carriers of HBV. HBV belongs to the family Hepadnaviridae, which also includes woodchuck hepatitis virus, ground squirrel hepatitis virus, tree squirrel hepatitis virus, and duck hepatitis B virus (DHBV) (3,(7)(8)(9)(10)(11)(12)(13)(14)19). All members of the hepadnavirus family have a number of characteristics in common such as morphological appearance, antigenic makeup, and DNA size and structure (3,(7)(8)(9)(10)(11)(12)(13)(14)19). Also, the pathological findings following infection with these viruses are quite similar (8,20). The replication of the hepadnaviruses (4, 10) is dependent on the reverse transcription of an RNA intermediate. This results in the formation of a minusstranded DNA, which then serves as a template for the synthesis of plus-stranded DNA.DHBV is able to propagate in primary duck hepatocytes in vitro. Tuttleman et al. (21) reported that upon infection of primary duck hepatocytes with DHBV, viral DNA is synthesized, virus-specific proteins are produced, and infectious virus is released into the culture medium. Using immunofluorescence, they demonstrated the production of both core and surface DHBV antigens in primary duck hepatocytes that were infected with DHBV. This in vitro system should prove suitable to evaluate the effects of antiviral drugs against DHBV. In this study, we examined a wide variety of such drugs that belong to the class of the purine and pyrimidine nucleoside analogs for their inhibitory effects on replication of DHBV in primary duck hepatocytes in vitro. was from ICN Nutritional Biochemicals, Cleveland, Ohio; 2',3'-dideoxy-2',3'-didehydrothymidine (D4T), 2',3'-dideoxyuridine (DDU), 2',3'-dideoxyadenosine (DDA), 2',3'-dideoxycytidine (DDC), 3'-deoxyarabinofuranosylcytidine (D-ara-C), 3'-azido-2',3'-dideoxythymidine (AZT), 3'-azido-2',3'-dideoxyuridine (AZU), acyclovir [9-(2-hydroxyeth...

Avenanthramides are characteristic constituents of oat seeds. We analyzed the methanol extract of oat seeds by HPLC and detected three compounds 1, 2, and 3 eluted at retention times similar to avenanthramides. The three compounds were purified by column chromatography and HPLC. Spectroscopic analyses of 1, 2, and 3 suggested that they are amides of 4,5-dihydroxyanthranilic acid with caffeic, p-coumaric, and ferulic acids, respectively. Their identities were confirmed by comparing spectra and chromatographic behavior with compounds synthesized from 4,5-dihydroxyanthranilic acid and N-hyrdroxysuccinimide esters of hydroxycinnamic acids. LC-MS/MS analysis with multiple reaction monitoring showed that the amounts of 1, 2, and 3 were 16.5-26.9% of corresponding avenanthamides with 5-hydroxyanthranilic acid. Compounds 1, 2, and 3 showed stronger 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity than the corresponding avenanthramides with 5-hydroxyanthranilic acid, indicating the involvement of 4,5-dihydroxyanthranilic acid moiety in the scavenging of DPPH radicals.

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