First Report of Sirococcus conigenus on Deodar Cedar in Oregon

Cedrus deodara is a highly valued conifer widely grown as an ornamental in the Pacific Northwest and southern United States. C. deodara in the Pacific Northwest is normally problem free but occasionally is damaged by dieback of shoot tips, which has been associated with a fungus resembling Sirococcus conigenus. In February 2002, bleeding cankers were observed on 2- to 4-year-old stems of potted nursery stock of C. deodara cv. Karl Fuchs from Clackamas County, OR. Cankers were dark with indistinct margins, shallow, and up to 30 cm long. Infection appeared to have originated with small twigs that had died. Cultures isolated from discolored bark on streptomycin-amended potato dextrose agar (PDA) produced conidiomata with hyaline, fusiform, two-celled conidia typical of S. conigenus (1,3). Inter-simple sequence repeat-polymerase chain reaction fingerprints of an isolate from one of these trees were consistent with the P group of S. conigenus (mostly from hosts in Picea and Pinus spp.) (2). This isolate (02-04, ATCC MYA-2969) was used to inoculate two shoots on each of 12 3-year-old potted deodar cedars in each of two trials. Removing a needle wounded each shoot, and an agar plug colonized with mycelium was placed over the wound and held in place for 2 weeks with Parafilm. Sterile agar plugs were applied to two wounded control shoots on each tree in each trial. After 10 weeks, 25 of 48 inoculated shoots were blighted and drooped with yellow to brown needles that eventually dropped. The pathogen was reisolated from 24 of 25 symptomatic shoots but not from asymptomatic or control shoots. To our knowledge, this is the first confirmed report of S. conigenus as a pathogen of C. deodara. References: (1) P. F. Cannon and D. W. Minter. Taxon 32:572, 1983. (2) D. R. Smith et al. For. Pathol. 33:141, 2003. (3) B. Sutton. The Coelomycetes. Commonw. Mycol. Inst., Kew, Surrey, England, 1980.

Quinolone, everninomycin, glycylcycline, carbapenem, lipopeptide and cephem antibacterials in clinical development

The development of antibacterials was a very successful endeavor in the pharmaceutical company repertoire through the late 1970s, when interest in investing in antibiotic research and development temporarily waned. More recently, there have been a number of failures in late stage development or post-launch of human antibiotics. The answer to the dilemma of less-than-desired success may be the introduction of novel classes of agents, as well as development of new agents in traditional classes. This review provides an overview of the various "miscellaneous" antibacterials in development, excluding glycopeptides, macrolides, ketolides, and oxazolidinones. Among the agents highlighted in this review are the clinical candidates of quinolones, everninomycins, carbapenems, lipopeptides, glycylcyclines, and cephems. In several cases, certain quinolone agents described in this review will have been approved for marketing before press time.

Anti-MRSA cephems. Part 1: C-3 substituted thiopyridinium derivatives

Sixteen novel cephalosporin derivatives with activity against methicillin-resistant Staphylococcus aureus (MRSA) are described. The compounds were synthesized using substituted thiopyridones, generated either by cyclization of functionalized precursors, or by direct alkylation of the enolate of 2-methyl substituted pyrones. The most active compound in vitro against a strain of MRSA (A27223) displayed an MIC of 0.5 microg/mL. The most efficacious compound in vivo had a PD50 of 2.1 mg/kg.

Biaryl diacid inhibitors of human s-PLA2 with anti-inflammatory activity

Twenty-four hydrophobic dicarboxylic acids are described which were evaluated as inhibitors of 14 kDa human platelet phospholipase A2 (HP-PLA2). In general, biarylacetic acid derivatives were found to be more active than biaryl acids or biarylpropanoic acids. More potent inhibitors were obtained when hydrophobic groups were attached to the biaryl acid nucleus using an olefin linkage as compared to an ether linkage. Compounds with larger hydrophobic groups were usually more potent inhibitors of HP-PLA2. Five of the compounds disclosed in this report (2, 4, 28, 36b and 36i) were found to possess significant anti-inflammatory activity in a phorbol ester induced mouse ear edema model of chronic inflammation.

4-Thiazolidinones: novel inhibitors of the bacterial enzyme MurB

4-Thiazolidinones were synthesized and evaluated for their ability to inhibit the bacterial enzyme MurB. Selected 4-thiazolidinones displayed activity against the enzyme in vitro. This activity, coupled with the design principles of the thiazolidinones, supports the postulate that 4-thiazolidinones may be recognized as diphosphate mimics by a biological selector.

Synthesis and antiviral activity of 2'-substituted 9-[2-(phosphonomethoxy)ethyl]guanine analogues

A series of 2'-substituted derivatives of 9-[2-(phosphonomethoxy)ethyl]guanine (PMEG, 1) have been synthesized and evaluated in vitro for anti-human immunodeficiency virus (HIV) activity in the XTT assay and for anti-herpes activity in the plaque reduction assay. It has been observed that the anti-HIV activity of these derivatives depends on the size and the nature of the substituent as well as the chirality at the 2'-position of PMEG. In addition, these compounds generally demonstrated greater activity against HIV than herpes viruses. The most interesting analogues which emerged from these studies are (R)-2'-(azidomethyl)-PMEG [(R)-5] and (R)-2'-vinyl-PMEG [(R)-11]. The former showed anti-HIV activity with an IC50 of 5 microM and a cytotoxicity (CC50) greater than 1.4 mM in CEM cells. The latter has an IC50 of 13 microM for anti-HIV activity and a CC50 of greater than 1.6 mM. Furthermore, we have demonstrated that replacement of the guanine base of these 2'-substituted PMEG analogues with cytosine drastically reduces anti-HIV and anti-herpes activity.

Synthesis and antiviral activity of methyl derivatives of 9-[2-(phosphonomethoxy)ethyl]guanine

A number of methyl derivatives of 9-[2-(phosphonomethoxy)ethyl]guanine (PMEG, 1) have been synthesized and tested in vitro for anti-herpes and anti-human immunodeficiency virus (HIV) activity. Among these analogues, (R)-2'-methyl-PMEG [(R)-3] and 2',2'-dimethyl-PMEG (7) demonstrated potent anti-HIV activity in the XTT assay with EC50 values of 1.0 and 2.6 microM, respectively. The corresponding (S)-2'-methyl-PMEG [(S)-3] was found to be less potent against HIV. In addition, the (R) and (S) enantiomers of 9-[3-hydroxy-2-(phosphonomethoxy)propyl]guanine (HPMPG, 8) were prepared for comparison of biological activity, and shown to be active and equipotent against herpesviruses, but inactive against HIV.

Intracellular metabolism of the antiherpes agent (S)-1-[3-hydroxy-2-(phosphonylmethoxy)propyl]cytosine

(S)-1-[3-Hydroxy-2-(phosphonylmethoxy)propyl]cytosine (HPMPC) is an antiviral phosphonate nucleotide analogue that displays activity against a range of herpesviruses. Anion exchange high performance liquid chromatography analysis of the 60% methanol extract from [14C]HPMPC-treated cells reveals the formation of three major metabolites. Two of these were identified as phosphorylated forms of HPMPC, HPMPC phosphate, and HPMPC diphosphate, by liberation of HPMPC upon acid digestion and coelution with synthetic standards on high performance liquid chromatography. The third metabolite, which is resistant to alkaline phosphatase cleavage but sensitive to phosphodiesterase, is proposed to be an HPMPC phosphate adduct. In herpes simplex virus-1-infected cells the same three metabolites are detected, at concentrations comparable to those in uninfected cells. When HPMPC is removed from the medium, the concentrations of the metabolites in cells decrease slowly, with half-lives of approximately 6, 17, and 48 hr for HPMPC phosphate, HPMPC diphosphate, and the HPMPC phosphate adduct, respectively. HPMPC diphosphate inhibits herpes simplex virus-1 and -2 DNA polymerases with a lower Ki than that for DNA polymerase alpha, and enzyme inhibition is competitive in each case. The formation and the persistence of HPMPC phosphates in cells and the selective inhibition of viral DNA polymerases by HPMPC diphosphate can explain why cells pretreated with HPMPC remain refractory to viral infection even long after HPMPC is removed from the medium.

Biochemical pharmacology of acyclic nucleotide analogues

Our studies have shown that the acyclic nucleotide analogues PMEA and HPMPC are able to penetrate into cells and are then activated to mono- and diphosphate derivatives. The latter correspond to triphosphate analogues and presumably serve an important role in the biological activity exerted by these antiviral agents. In support of this idea, the inhibitory effect of PMEApp on HIV reverse transcriptase has been demonstrated with both RNA and DNA template-primer systems. Further studies will be undertaken to determine the effect of HPMPCpp on viral DNA polymerases. Whereas the metabolism of PMEA in CEM cells gives rise to only PMEAp and PMEApp, additional metabolites were obtained in MRC-5 cells; the identity of these metabolites remains to be determined. In the case of HPMPC, a third metabolite was obtained in addition to HPMPCp and HPMPCpp, which has been tentatively assigned as a phosphate-choline adduct by analogy with activation of cytosine-based nucleoside derivatives. The metabolism of HPMPC was unchanged between uninfected and infected cells, indicating that viral enzymes are not necessary for the activation of HPMPC. The long intracellular half-lives of the HPMPC metabolites may have implications for the antiviral efficacy of this compound. The persistence of activated metabolites suggests that infrequent dosing may be possible due to a prolonged antiviral effect. Our results on the effectiveness of infrequent dosing schedules with HPMPC in the treatment of HSV 2 infections in mice support this hypothesis. It is also possible that HPMPCp-choline may serve as a reservoir for HPMPC and therefore for the presumed active metabolite HPMPCpp.

Acyclic purine phosphonate analogues as antiviral agents. Synthesis and structure-activity relationships

A series of 9-(phosphonoalkyl)purines, which are analogues of 9-[2-(phosphonomethoxy)ethyl]purines (guanine, PMEG, 1; adenine, PMEA, 2), were synthesized. The analogues were tested for activity against herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), human cytomegalovirus (HCMV), Rauscher murine leukemia virus (R-MuLV), and human immunodeficiency virus type 1 (HIV-1). With variations in the length of the alkyl chain, the optimal activity was achieved with two carbons between the purine base and the phosphonomethoxy functionality. Despite the structural similarity and the close pKa2 value of 8 to that of PMEG, no phosphorylation of 8 was observed by the bovine brain guanylate kinase. Since all isosteric analogues of PMEG (7-9) were not inhibitory against HSV-1 and HSV-2, the presence of the 3'-oxygen atom in the PME purines proved critical for anti-HSV activity. Introduction of the 1'-methyl group on the PMEG side chain significantly reduced its anti-HSV activity. Analogue 11, which is a mimic of the phosphate by incorporation of the alpha,alpha-difluoro carbon, was ineffective against HSV-1 and HSV-2. These results suggest that the structural requirements of PME purines for anti-HSV activity appear to be very strict.

In vivo antitumor activity of 9-[(2-phosphonylmethoxy)ethyl]-guanine and related phosphonate nucleotide analogues

Phosphonylmethoxyalkylpurine analogues were evaluated for their antitumor activity in murine tumor models. Three compounds, (S)-9-[(3-hydroxy-2-phosphonylmethoxy)propyl]adenine (HPMPA), 9-[(2-phosphonylmethoxy)ethyl]adenine (PMEA), and 9-[(2-phosphonylmethoxy)ethyl]guanine (PMEG) were modestly active with treated versus control (T/C) values of 125%-175% versus intraperitoneal P388 leukemia, but were inactive versus intravenously implanted P388. The most active and most potent of the three was PMEG, which was also evaluated against subcutaneously (SC) implanted B16 melanoma. In confirmatory experiments, optimal therapy with PMEG yielded reproducible increases in life span (T/C values of 164%-170%) and delays in primary tumor growth (7.3- to 13.0-day T-C values). PMEG is representative of a new class of antitumor antimetabolites heretofore recognized only for their antiviral properties.

Synthesis and antiviral activity of the nucleotide analogue (S)-1-[3-hydroxy-2-(phosphonylmethoxy)propyl]cytosine

The acyclic nucleotide analogue (S)-1-[3-hydroxy-2-(phosphonylmethoxy)propyl] cytosine (2, HPMPC) was prepared on a multigram scale in 18% overall yield starting from (R)-2,3-O-isopropylideneglycerol. The key step in the nine-step synthetic route is coupling of cytosine with the side-chain derivative 8 which bears a protected phosphonylmethyl ether group. In vitro data showed that HPMPC has good activity against herpes simplex virus types 1 and 2, although it was 10-fold less potent than acyclovir [AVC, 9-[(2-hydroxyethoxy)methyl]guanine]. By comparison, HPMPC exhibited greater activity than ACV against a thymidine kinase deficient strain of HSV 1 and was more potent than ganciclovir [DHPG, 9-[(1,3-dihydroxy-2-propoxy)methyl]guanine] against human cytomegalovirus. In vivo, HPMPC showed exceptional potency against HSV 1 systemic infection in mice, having an ED50 of 0.1 mg/kg per day (ip) compared with 50 mg/kg per day for ACV. HPMPC was also more efficacious than ACV in the topical treatment of HSV 1 induced cutaneous lesions in guinea pigs.