Antineoplastic agents. Part 409: Isolation and structure of montanastatin from a terrestrial actinomycete.

A Montana soil actinomycete, Streptomyces anulatus, produced (1 x 10(-2)% yield) a new cancer cell growth inhibitory cyclooctadepsipeptide named montanastatin (1) accompanied by the potent anticancer antibiotic valinomycin (2) in very high (5.1%) yields. Valinomycin but not montanastatin inhibited growth of a number of pathogenic bacteria and fungi. Interpretation of high-field (500 MHz) NMR and high-resolution FAB mass spectral data allowed assignment of the structure cyclo-(D-Val-L-Lac-L-Val-D-Hiv) to montanastatin. Valinomycin (2) was also isolated from actinomycetes cultured from a tree branch and animal feces collected in Malaysia. Streptomyces exfoliatus, isolated from the tree branch, was found to contain valinomycin in 1.6% yield, while the fecal isolate, S. anulatus, gave valinomycin in 0.9% yield.     

An AFLP-based genetic linkage map of Plasmodium chabaudi chabaudi

Background

Plasmodium chabaudi chabaudi can be considered as a rodent model of human malaria parasites in the genetic analysis of important characters such as drug resistance and immunity. Despite the availability of some genome sequence data, an extensive genetic linkage map is needed for mapping the genes involved in certain traits.

Methods

The inheritance of 672 Amplified Fragment Length Polymorphism (AFLP) markers from two parental clones (AS and AJ) of P. c. chabaudi was determined in 28 independent recombinant progeny clones. These, AFLP markers and 42 previously mapped Restriction Fragment Length Polymorphism (RFLP) markers (used as chromosomal anchors) were organized into linkage groups using Map Manager software.

Results

614 AFLP markers formed linkage groups assigned to 10 of 14 chromosomes, and 12 other linkage groups not assigned to known chromosomes. The genetic length of the genome was estimated to be about 1676 centiMorgans (cM). The mean map unit size was estimated to be 13.7 kb/cM. This was slightly less then previous estimates for the human malaria parasite, Plasmodium falciparum

Conclusion

The P. c. chabaudi genetic linkage map presented here is the most extensive and highly resolved so far available for this species. It can be used in conjunction with the genome databases of P. c chabaudi, P. falciparum and Plasmodium yoelii to identify genes underlying important phenotypes such as drug resistance and strain-specific immunity.     

A Globin Domain in a Neuronal Transmembrane Receptor of Caenorhabditis elegans and Ascaris suum: MOLECULAR MODELING AND FUNCTIONAL PROPERTIES*

We report the structural and biochemical characterization of GLB-33, a putative neuropeptide receptor that is exclusively expressed in the nervous system of the nematode Caenorhabditis elegans. This unique chimeric protein is composed of a 7-transmembrane domain (7TM), GLB-33 7TM, typical of a G-protein-coupled receptor, and of a globin domain (GD), GLB-33 GD. Comprehensive sequence similarity searches in the genome of the parasitic nematode, Ascaris suum, revealed a chimeric protein that is similar to a Phe-Met-Arg-Phe-amide neuropeptide receptor. The three-dimensional structures of the separate domains of both species and of the full-length proteins were modeled. The 7TM domains of both proteins appeared very similar, but the globin domain of the A. suum receptor surprisingly seemed to lack several helices, suggesting a novel truncated globin fold. The globin domain of C. elegans GLB-33, however, was very similar to a genuine myoglobin-type molecule. Spectroscopic analysis of the recombinant GLB-33 GD showed that the heme is pentacoordinate when ferrous and in the hydroxide-ligated form when ferric, even at neutral pH. Flash-photolysis experiments showed overall fast biphasic CO rebinding kinetics. In its ferrous deoxy form, GLB-33 GD is capable of reversibly binding O₂ with a very high affinity and of reducing nitrite to nitric oxide faster than other globins. Collectively, these properties suggest that the globin domain of GLB-33 may serve as a highly sensitive oxygen sensor and/or as a nitrite reductase. Both properties are potentially able to modulate the neuropeptide sensitivity of the neuronal transmembrane receptor.     

Algorithm for diagnosis of early Schistosoma haematobium using prodromal signs and symptoms in pre-school age children in an endemic district in Zimbabwe

IntroductionPrompt diagnosis of acute schistosomiasis benefits the individual and provides opportunities for early public health intervention. In endemic areas schistosomiasis is usually contracted during the first 5 years of life, thus it is critical to look at how the infection manifests in this age group. The aim of this study was to describe the prodromal signs and symptoms of early schistosomiasis infection, correlate these with early disease progression and risk score to develop an easy to use clinical algorithm to identify early Schistosoma haematobium infection cases in resource limited settings.MethodologyTwo hundred and four, preschool age children who were lifelong residence of a schistosomiasis endemic district and at high risk of acquiring schistosomiasis were followed up from July 2019 to December 2019, during high transmission season. The children received interval and standard full clinical evaluations and laboratory investigations for schistosomiasis by clinicians blinded from their schistosomiasis infection status. Diagnosis of S. haematobium was by urine filtration collected over three consecutive days. Signs and symptoms of schistosomiasis at first examination visit were compared to follow-up visits. Signs and symptoms common on the last schistosomiasis negative visit (before a subsequent positive) were assigned as early schistosomiasis infection (ESI), after possible alternative causes were ruled out. Logistic regression identified clinical predictors. A model based score was assigned to each predictor to create a risk for every child. An algorithm was created based on the predictor risk scores and validated on a separate cohort of 537 preschool age children.ResultsTwenty-one percent (42) of the participants were negative for S. haematobium infection at baseline but turned positive at follow-up. The ESI participants at the preceding S. haematobium negative visit had the following prodromal signs and symptoms in comparison to non-ESI participants; pruritic rash adjusted odds ratio (AOR) = 21.52 (95% CI 6.38–72.66), fever AOR = 82 (95% CI 10.98–612), abdominal pain AOR = 2.6 (95% CI 1.25–5.43), pallor AOR = 4 (95% CI 1.44–11.12) and a history of facial/body swelling within the previous month AOR = 7.31 (95% CI 3.49–15.33). Furthermore 16% of the ESI group had mild normocytic anaemia, whilst 2% had moderate normocytic anaemia. A risk score model was created using a rounded integer from the relative risks ratios. The diagnostic algorithm created had a sensitivity of 81% and a specificity of 96.9%, Positive predictive value = 87.2% and NPV was 95.2%. The area under the curve for the algorithm was 0.93 (0.90–0.97) in comparison with the urine dipstick AUC = 0.58 (0.48–0.69). There was a similar appearance in the validation cohort as in the derivative cohort.ConclusionThis study demonstrates for the first time prodromal signs and symptoms associated with early S. haematobium infection in pre-school age children. These prodromal signs and symptoms pave way for early intervention and management, thus decreasing the harm of late diagnosis. Our algorithm has the potential to assist in risk-stratifying pre-school age children for early S. haematobium infection. Independent validation of the algorithm on another cohort is needed to assess the utility further.     

Identification of lignans and related compounds in Anthriscus sylvestris by LC-ESI-MS/MS and LC-SPE-NMR

The aryltetralin lignan deoxypodophyllotoxin is much more widespread in the plant kingdom than podophyllotoxin. The latter serves as a starting compound for the production of cytostatic drugs like etoposide. A better insight into the occurrence of deoxypodophyllotoxin combined with detailed knowledge of its biosynthestic pathway(s) may help to develop alternative sources for podophyllotoxin. Using HPLC combined with electrospray tandem mass spectrometry and NMR spectroscopy techniques, we found nine lignans and five related structures in roots of Anthriscus sylvestris (L.) Hoffm. (Apiaceae), a common wild plant in temperate regions of the world. Podophyllotoxone, deoxypodophyllotoxin, yatein, anhydropodorhizol, 1-(3′-methoxy-4′,5′-methylenedioxyphenyl)1-ξ-methoxy-2-propene, and 2-butenoic acid, 2-methyl-4-[[(2Z)-2-methyl-1-oxo-2-buten-1-yl]oxy]-, (2E)-3-(7-methoxy-1,3-benzodioxol-5-yl)-2-propen-1-yl ester, (2Z)- were the major compounds. α-Peltatin, podophyllotoxin, β-peltatin, isopicropodophyllone, β-peltatin-a-methylether, (Z)-2-angeloyloxymethyl-2-butenoic acid, anthriscinol methylether, and anthriscrusin were present in lower concentrations. α-Peltatin, β-peltatin, isopicropodophyllone, podophyllotoxone, and β-peltatin-a-methylether have not been previously reported to be present in A. sylvestris. Based on our findings we propose a hypothetical biosynthetic pathway of aryltetralin lignans in A. sylvestris.     

The crystal structure of 3 beta-hydroxy-4 alpha, 23R, 24R-trimethyl-5 alpha-cholestane (23R, 24R-5 alpha-dinostanol) from dinoflagellates

An x-ray crystal structure determination of a dinostanol from the dinoflagellate Protoceratium reticulatum and zooxanthellae from Orbulina universa was completed. The novel sterol was shown to be 3 beta-hydroxy-4 alpha, 23R,24R-trimethyl-5 alpha-cholestane and may be one of the molecular fossils found in sediment cores from the deepest Black Sea trench.     

Antineoplastic agents 582. Part 1: Isolation and structure of a cyclobutane-type sesquiterpene cancer cell growth inhibitor from Coprinus cinereus (Coprinaceae)

Bioassay-guided (murine P388 lymphocytic leukemia and human cancer cell lines) separation of an ethyl acetate extract prepared from the inky cap fungus Coprinus cinereus led to the isolation of three new sesquiterpenes, 7,7a-diepicoprinastatin 1 (1), 14-hydroxy-5-desoxy-2S,3S,9R-illudosin (2), and 4,5-dehydro-5-deoxyarmillol (3), together with the known armillol (4). The structure and relative configuration of 1 was determined by single-crystal X-ray diffraction experiments. The structures of compounds 2, 3, and 4 were each deduced by a combination of HRMS and 1D and 2D NMR techniques. Cyclobutane 2 led to modest inhibition of the murine P388 leukemia cell line.