NCI Program for Natural Product Discovery: A Publicly-Accessible Library of Natural Product Fractions for High-Throughput Screening.

The US National Cancer Institute's (NCI) Natural Product Repository is one of the world's largest, most diverse collections of natural products containing over 230,000 unique extracts derived from plant, marine, and microbial organisms that have been collected from biodiverse regions throughout the world. Importantly, this national resource is available to the research community for the screening of extracts and the isolation of bioactive natural products. However, despite the success of natural products in drug discovery, compatibility issues that make extracts challenging for liquid handling systems, extended timelines that complicate natural product-based drug discovery efforts and the presence of pan-assay interfering compounds have reduced enthusiasm for the high-throughput screening (HTS) of crude natural product extract libraries in targeted assay systems. To address these limitations, the NCI Program for Natural Product Discovery (NPNPD), a newly launched, national program to advance natural product discovery technologies and facilitate the discovery of structurally defined, validated lead molecules ready for translation will create a prefractionated library from over 125,000 natural product extracts with the aim of producing a publicly-accessible, HTS-amenable library of >1,000,000 fractions. This library, representing perhaps the largest accumulation of natural-product based fractions in the world, will be made available free of charge in 384-well plates for screening against all disease states in an effort to reinvigorate natural product-based drug discovery.

Tetramic acid analogues produced by coculture of Saccharopolyspora erythraea with Fusarium pallidoroseum.

Coculture of the fungus Fusarium pallidoroseum with the bacterium Saccharopolyspora erythraea was found to produce three new decalin-type tetramic acid analogues related to equisetin. The structures were determined by spectroscopic methods. The absolute configurations were established by circular dichroism spectroscopy and comparing the data with those of equisetin.

Histone deacetylase inhibitors from Burkholderia thailandensis.

Bioactivity-guided fractionation of an extract of Burkholderia thailandensis led to the isolation and identification of a new cytotoxic depsipeptide and its dimer. Both compounds potently inhibited the function of histone deacetylases 1 and 4. The monomer, spiruchostatin C (2), was tested side by side with the clinical depsipeptide FK228 (1, Istodax, romidepsin) in a murine hollow fiber assay consisting of 12 implanted tumor cell lines. Spiruchostatin C (2) showed good activity toward LOX IMVI melanoma cells and NCI-H522 non small cell lung cancer cells. Overall, however, FK228 (1) showed a superior in vivo antitumor profile in comparison to the new compound.

Induced production of N-formyl alkaloids from Aspergillus fumigatus by co-culture with Streptomyces peucetius.

Co-culture of the fungus Aspergillus fumigatus with the bacteria Streptomyces peucetius led to the induction of production of formyl xanthocillin analogues. This mixed fermentation yielded two new metabolites, fumiformamide (1) and N,N'-((1Z,3Z)-1,4-bis(4-methoxyphenyl)buta-1,3-diene-2,3-diyl)diformamide (2), together with two known N-formyl derivatives and the xanthocillin analogue BU-4704. The structures were determined by spectroscopic methods and by comparison with literature. Cytotoxic activity of all the analogues was tested on the NCI-60 cell line screen, and compound 2 exhibited significant activity against several cell lines. The analogues did not show antimicrobial activity.

An inhibitor of CCL2-induced chemotaxis from the fungus Leptoxyphium sp.

A biological screen used to identify inhibitors of monocyte chemotactic protein-1 (CCL2)-induced chemotaxis was applied in the activity-guided fractionation of an extract from a fungus of the genus Leptoxyphium sp. Inhibition of CCL2-induced chemotaxis was traced to a new dichlorinated diketopiperazine, cyclo(13,15-dichloro-L-Pro-L-Tyr). A structure-activity relationship (SAR) study evaluating relative activities of cyclo(13,15-dichloro-L-Pro-L-Tyr) and a nonchlorinated homologue cyclo(L-Pro-L-Tyr) showed that the dichlorinated molecule was 10- to 20-fold more active than the nonchlorinated form, while no activity was observed for cyclo(D-N-methylLeu-L-Trp).

Herpes simplex virus infection causes cellular beta-amyloid accumulation and secretase upregulation.

It is uncertain whether environmental factors contribute to the formation of senile plaques and neurofibrillary tangles, the abnormal features that define the Alzheimer's disease (AD) brain. We previously proposed that herpes simplex virus type 1 (HSV1) is a strong risk factor for AD when it is present in the brains of people who possess the type 4 allele of the apolipoprotein E gene (APOE-epsilon4); however a direct biochemical link between viral infection and the development of the AD pathological features has never previously been examined. Here we show that infection of cultured neuronal and glial cells with HSV1 leads to a dramatic increase in the intracellular levels of beta-amyloid (Abeta) 1-40 and 1-42, whilst levels of amyloid precursor protein (APP) in cells decrease. Similarly, Abeta1-42 deposits are present in mouse brain after HSV1 infection. In the cultured cells the mechanism involves increased Abeta production, rather than merely greater retention of cellular Abeta, as levels of beta-site APP-cleaving enzyme (BACE-1) and of nicastrin, a component of gamma-secretase, both increase in HSV1-infected cells. These novel data show that HSV1 can directly contribute to the development of senile plaques.

Does apolipoprotein E determine outcome of infection by varicella zoster virus and by Epstein Barr virus?

Over 90% of the population are infected with varicella zoster virus (VZV) but only some develop shingles - caused when the virus reactivates from latency, and only some shingles patients develop post-herpetic neuralgia (PHN), defined as pain continuing for more than about 4 months. Epstein Barr virus (EBV) similarly infects over 90% of the population; some of those infected during teenage or young adult years develop infectious mononucleosis (IM). The reason for these disparities between numbers infected and numbers affected by illness is unknown, but presumably reflects host factor(s). Our previous results showed that apolipoprotein E (APOE) genotype determines susceptibility to, or outcome of, infection in the case of several diseases of known infectious cause. Therefore, we investigated APOE genotypes of shingles, PHN, and IM patients. Our rationale for the previous studies and for investigating VZV was that these micro-organisms use for cell binding and entry the same sites in the cell surface as does the protein apoE, and that consequently, competition with apoE could affect the pathogen's extent of entry and hence extent of the damage caused. The APOE genotypes of shingles and PHN sufferers, and of IM sufferers were determined using restriction fragment length polymorphism. In females, epsilon4 homozygosity confers a risk of shingles and also of IM, and the APOE-epsilon4 allele is protective against PHN whereas APOE-epsilon3 allele is a risk. Our results showing that a host genetic factor influences the development of shingles and PHN in females have clinical significance: they could lead to identification of those (female) patients at greater risk of PHN, thus enabling these people to be targeted for treatment with the most effective drugs.

Herpes simplex virus interferes with amyloid precursor protein processing.

BACKGROUND: The early events underlying Alzheimer's disease (AD) remain uncertain, although environmental factors may be involved. Work in this laboratory has shown that the combination of herpes simplex virus type 1 (HSV1) in brain and carriage of the APOE-epsilon4 allele of the APOE gene strongly increases the risk of developing AD. The development of AD is thought to involve abnormal aggregation or deposition of a 39-43 amino acid protein--beta amyloid (Abeta)--within the brain. This is cleaved from the much larger transmembranal protein 'amyloid precursor protein' (APP). Any agent able to interfere directly with Abeta or APP metabolism may therefore have the capacity to contribute towards AD. One recent report showed that certain HSV1 glycoprotein peptides may aggregate like Abeta; a second study described a role for APP in transport of virus in squid axons. However to date the effects of acute herpesvirus infection on metabolism of APP in human neuronal-type cells have not been investigated. In order to find if HSV1 directly affects APP and its degradation, we have examined this protein from human neuroblastoma cells (normal and transfected with APP 695) infected with the virus, using Western blotting. RESULTS: We have found that acute HSV1 (and also HSV2) infection rapidly reduces full length APP levels--as might be expected--yet surprisingly markedly increases levels of a novel C-terminal fragment of APP of about 55 kDa. This band was not increased in cells treated with the protein synthesis inhibitor cycloheximide CONCLUSION: Herpes virus infection leads to rapid loss of full length APP from cells, yet also causes increased levels of a novel 55 kDa C-terminal APP fragment. These data suggest that infection can directly alter the processing of a transmembranal protein intimately linked to the aetiology of AD.

Clearance of hepatitis C virus is not associated with single nucleotide polymorphisms in the IL-1, -6, or -10 genes.

Hepatitis C virus (HCV) commonly causes a chronic infection, but a minority of patients are able to clear the virus and do not run the risk of developing HCV-induced organ damage. Genetic associations between immunoregulatory cytokines interleukin (IL)-1, -6, and -10 with clinical features of HCV, including virus clearance, have been inconsistent. We determined cytokine genotypes in 606 patients who had serologic evidence of HCV exposure, 190 (18%) of whom were consistently negative for HCV RNA, indicating successful virus clearance. There was no significant difference in genotype frequencies between HCV clearance and nonclearance groups for IL-1B (-511 and +3954), IL-1A (+4845), IL-1RN (+2018), IL-6 (-174), or IL-10 (-1082). We conclude that these single nucleotide polymorphisms are unlikely to play an important, if any, role in determining the likelihood of clearing HCV infection.

Productive herpes simplex virus in brain of elderly normal subjects and Alzheimer's disease patients.

It was previously shown that herpes simplex virus type 1 (HSV1) DNA resides latently in a high proportion of aged brains and that in carriers of the type 4 allele of the apolipoprotein E gene (APOE-epsilon4), it confers a strong risk of Alzheimer's disease. It was suggested that initial entry of brain by HSV1 and any subsequent reactivation(s) would cause a type of limited encephalitis, the resulting damage being more harmful in APOE-epsilon4 carriers. Reactivation(s) would induce synthesis of intrathecal antibodies; these are long-lived after herpes simplex encephalitis so they were sought in cerebrospinal fluid (CSF) of Alzheimer's disease patients and age-matched normal subjects. Intrathecal antibodies to human herpesvirus 6 (HHV6) were also sought as DNA of this virus has been detected previously in a high proportion of Alzheimer's disease brains. Antibody indices for HSV and HHV6 were measured using indirect ELISA for IgG antibody, and single radial immunodiffusion was used for albumin, in serum and CSF. A raised antibody index (>1.5) indicative of virus-specific intrathecal HSV1 IgG synthesis was found in 14/27 (52%) Alzheimer's disease patients and 9/13 (69%) age-matched normals (difference non-significant). A raised antibody index to HHV6 was detected in 22% of the Alzheimer's disease patients and in no normals, so presumably this virus either did not reactivate in brain or it elicited only short-lived intrathecal antibodies. The HSV1 results confirm the original PCR findings that show the presence of HSV1 DNA sequences in many elderly brains, and indicate also that the whole functional HSV1 genome is present, and that the virus has replicated.