Condensation of 4,5‐diaminopyrimidines 2 and 3 with 2,2ʹ‐dipyridil (4) afforded 6,7‐bis(2‐pyridyl)pteridine‐2‐one analogues 5 and 7, respectively. Analogously, 6,7‐bis(2‐pyridyl)luamzine derivatives 13, 15, 17, and 23 were synthesized from reaction of 5,6‐diamino‐2‐thiopyrimidines 13, 14, and 22 with 4, respectively, while condensation of 4,5,6‐triaminopyrimidines (25) or 5,6‐diamino analogue 26 with 4 furnished the 4‐amino‐pteridine analogue 27 and 28, respectively. Thiation of the new pteridines and lumazines afforded the 4‐thio analogues 6, 8, 16, and 24. Treatment of 6 and 8 with methanolic ammonia afforded the 4‐isopterine analogues 9 and 10, respectively. Alkylation of 15 with substituted phenacyl chloride furnished 18 and 19, which cyclized to the thiazolo‐pteridine derivatives 20 and 21, respectively, on treatment with polyphosphoric acid. Alternatively, 27 was prepared from treatment of 24 with methanolic ammonia under drastic conditions. Condensation of 2 or 29 with 2‐oxo‐2‐(thiophen‐2‐yl)acetaldehyde oxime (11) gave the 6‐(2‐thienyl)‐pteridine‐4‐one (12) and 5‐chloro‐2‐(2‐thienyl)pyrido[3,4‐b]pyrazine (31), respectively. All compounds were evaluated for their antiviral activity against the replication of HIV‐1 and HIV‐2 in MT‐4. Some of the synthesized compounds were tested against the bacterial species, Escherichia coli and Staphylococcus aureus, as well as fungal species, Candida tropicalis and Candida albicans.

Background Ecological killer yeasts have had few studies compared with laboratory killer yeasts. The killer yeasts are known in excreting killer toxins that kill sensitive or susceptible yeasts. The killer toxins, such as TK and WK excreted from two yeast isolates (Torulaspora delbrueckii and Wickerhamomyces anomalus) have protenious nature with different molecular weight depending on yeast species. Results A qualitative test was conducted to determine the ability of both isolates to produce killer toxins on the media of yeast extract and malt extract broth when the two toxins were first purified by ammonium sulfate salt at 40% concentration and then by dialysis for the killer toxin TK and gel filtration method for WK. The molecular weight of TK was estimated at about 15 kDa, while WK was at 45 kDa. The chemical properties of the killer toxins were also studied. The results showed that the two killer toxins were with protenious nature. Conclusion Both yeast isolates (Torulaspora delbrueckii and Wickerhamomyces anomalus) had the ability of producing different kinds of killer toxins. The two killer toxins (TK and WK) were identified for the first time in Iraq, and their production involves many steps of economically unexpansive purification method with a good quality and high purity of producing killer toxins. The results confirmed that the nature of killer toxins (WK and TK) was similar to protein compounds resulted from the transition in UV and functional groups.

Background This study was conducted to estimate the antifungal activity and efficiency of purified killer toxins (TK and WK) produced by Torulaspora delbrueckii and Wickerhamomyces anomalus as alternative drugs of resistant strains against several pathogenic fungi (Candida albicans, Aspergillus niger, and Aspergillus flavus). A specific focus was on the antifungal activity of such purified proteins by using a simple and economical tools under controlled conditions of fermentations. Results The results showed that the optimum conditions of these experiments were detected at 30 °C, 150 rpm, pH 4.5, 3 days incubation period and by using one culture medium (yeast malt extract broth with 2% SDS). The extracted crude toxin had an excellent effect on Candida albicans, Aspergillus niger, and Aspergillus flavus. The inhibition zone values were 35 and 30 mm for WK and TK, respectively, against Candida albicans. While the lowest values of inhibition zone were recorded at 25 mm for WK and 18 mm for TK against Aspergillus flavus. The WK killer toxins were in general more active against the three clinical strains compared to the TK that had the lowest inhibitory effect. Conclusion This study is conducted for the first time in Iraq to determine the optimum conditions for producing two types of killer toxins and testing their antifungal activity. The optimal killer activity was obtained at low pH and mesophilic temperature. The two yeast strains had a good role in the reduction of radial growth of tested pathogenic fungi

This study was conducted to isolate and identify killer yeasts from soil samples that collected from different locations in Basrah and Dhi-Qar provinces. Seventy-five soil samples were collected from different areas, including sandy, arable, surface sediment and uncultivated soil, using dilution methods to cultivate a serial dilution of each soil sample. The results showed that a 112 isolates were identified biochemically using VITEK system and molecularly using internal transcribed spacer (ITS1- 5.8S-ITS2) marker. The molecular identification provided fast and precise identification results for the 112 isolates, whereas the VITEK test resulted low identification efficiency (8.2% were accurate and 91.8 % were not). The Diazonium blue B salts produced a good colour reaction in distinguishing between ascomycetes and basidiomycetes. The PCR was more accurate in identification of killer yeasts compared to the VITEK system.

Soil is one of the favorable habitat for microorganism. It considered being the home of wide range of them in particularly, bacteria and fungi. Southern Iraq is characterized by a multiplicity of ecosystem, which include desert, agricultural and marine areas, each of which has special composition that differs from the neighboring system, whether in terms of vegetation or various environmental factors. This in diversity, in turn, may lead to microbial diversity that can be used in different biotechnologies. Regarding that little is known about yeast diversity in such habitats, and therefore the current study aims to assess the yeast community in soil and sediments samples from Basrah and Dhi-Qar provinces, Southern Iraq. Thirty-one species belong to 19 genera were encountered. The isolated species consist of 16 species of Ascomycota and 15 species of Basidiomycota. The soil of Basrah and Dhi-Qar support the growth of diverse species belonged to the genera Aureobasidium, Cutaneotrichosporon, Debaryomyces, Filobasidium Geotrichum, Hanseniaspora, Lodderomyces, Meyerozyma, Symmetrospora, Torulaspora, Vishniacozyma, Pichia, Yarrowia, Cystobasidium, Galactomyces, Rhodotorula, Wickerhamomyces, Candida and Naganishia. One hundred and twelve fungal isolates were identified using the conventional methods depending on morphological characteristics. CHROMagar candida was used as differential culture medium. Iodine stain was used to differentiate ascospores and basidiospores. In addition biochemical method represented by VITEK was used as well as molecular identification. This study represents the first report of occurrence of yeast species in soil and surface sediment samples from Basrah and Dhi-Qar provinces, Southern, Iraq, with effect of some ecological factors on isolation yeast from different location.