Natural Dyes in Cyanide and Anion Sensing

Cyanide is one of anions of concern due to its high toxicity. It causes death at a low dosage (2.6 mM) and the allowable level should be lower than 1.9 mmolar according to World health Organization (WHO). Cyanide contamination in the environment comes from many sources as metallurgy, gold mining, cyanide fishing, manufacturing acrylonitriles and related polymers, and natural sources. Cyanide also is present in some foods and food products such as cassava, bitter almonds, apple seeds, and some beans. The wide spread of cyanide in these food is of concern and the levels should be monitored and evaluated. In addition cyanide, may leak and get into water bodies or soil accidentally or intentionally, therefore, developing an easy, simple method for its detection is a priority. Many methods have been developed for detection of cyanide and anions such as titrations, distillations, GC-ECD, and spectrophotometrically. Colorimetric methods have been developed which are easy and simple that can give qualitative results visually and quantitatively using absorption or fluorescence spectroscopy. We have tuned into using dyes and natural dyes that are none toxic and available to use as visual (colorimetric) using both absorption and fluorescence techniques. Curcumin [1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione] is obtained from dry rhizomes of Curcuma longa, as the main yellow pigment used as spices, cosmetic and traditional medicine. It has been reported that curcumin also has many pharmacological functions like antioxygenation, antibiosis and antitumor. Despite the fact that extensive colorimetric and related photophysical studies of curcumin has been extensively studied, less study has done on its potentiality in application as a colorimetric and naked eye sensor of biologically and environmentally important anions like fluoride, acetate and phosphate. Some studies reported interaction of curcumin with cyclodextrin based on changes in basicity in acetonitrile which showed its importance in supramolecular chemistry. We herein describe a simple and efficient visible colorimeric cyanide and fluoride ions detection using commercially available curcumin as a receptor. The method could allow application in detection of curcumin, fluoride and cyanide, important chemical and biological species The choice of curcumin as a sensor for anion was mainly based on the fact that curcumin is a phenol and therefore exist in a equilibrium between its protonated and deprotonated forms in relatively basic media. It also contains a carbonyl group succeptable to nucleophilic addition, this will make it have two anion receptors., hydroxyl for hydrogen bonding to associate with basic anions. The carbonyl is areceptor for nucleophilc anions such as cyanide. Due to this reason curcumin can interact differently with different anions and enhance its selectivity based on the sovent choice. It will behave as a chemodosimeter. Acetonitrile, a polar aprotic solvent is is a good media for the analysis, it does not compete with anion in the recognition sites of curcumin. Variation in color changes of curcumin in acetonitrile was done by addition of aliquots of various anions as tetrabutylammonium salts. Addition of fluoride and cyanide ions induced color change from yellow, purple, blue to deep blue with intensity at every level dependent on the fluoride ion concentration. Acetate ion changed the color of solution to light purple, while dihydrogen phosphate induced only a tinge of color enhancement. Chloride, bromide and perchlorate were found to show no effect on the solution of curcumin. In an aquaeous acetonitrile solution the effect was observed only for cyanide only with a clear color change from yellow to red. While other anions had no significant effect. This indicates that the mechanism of interaction is based on nucleophilic addition in the case of cyanide in aqueous media and hydrogen bonding in nonpeotoc solvents. The stoichiometry was determinned to be 1:1 for cyanide and 1:2 for fluoride. The binding constants and detection limits were calculated form the UV-vis absorption titrations. In this presentation the method, structures of dye and complexes, the titration curves, color changes, binding constants and aplication will be discussed.qscienc

Two new sponge species (Demospongiae: Chalinidae and Suberitidae) isolated from hyperarid mangroves of Qatar with notes on their potential antibacterial bioactivity.

This study presents the taxonomic description of two new sponge species that are intimately associated with the hyperarid mangrove ecosystem of Qatar. The study includes a preliminary evaluation of the sponges' potential bioactivity against pathogens. Chalinula qatari sp. nov. is a fragile thinly encrusting sponge with a vivid maroon colour in life, often with oscular chimneys and commonly recorded on pneumatophores in the intertidal and shallow subtidal zone. Suberites luna sp. nov. is a massive globular-lobate sponge with a greenish-black colour externally and a yellowish orange colour internally, recorded on pneumatophores in the shallow subtidal zone, with large specimens near the seagrass ecosystem that surrounds the mangrove. For both species, a drug extraction protocol and an antibacterial experiment was performed. The extract of Suberites luna sp. nov. was found to be bioactive against recognized pathogens such as Staphylococcus epidermidis, Staphylococcus aureus and Enterococcus faecalis, but no bioactive activity was recorded for Chalinula qatari sp. nov. This study highlights the importance of increasing bioprospecting effort in hyperarid conditions and the importance of combining bioprospecting with taxonomic studies for the identification of novel marine drugs.QNRF/URE

Substituted 2-Aminobenzothiazoles Salicylidenes Synthesis and Characterization as Cyanide Sensors in Aqueous Medium

(E)-2-((benzo[d]thiazol-2-ylimino)methyl)-4-nitrophenol 1 and (E)-2-(((6-methoxybenzo[d]thiazol-2-yl)imino)methyl)-4-nitrophenol 2 were synthesized efficiently under microwave conditions. The structures were confirmed using IR, 1H NMR, and 13C NMR. UV-vis. Fluorescence investigations demonstrated that 1 and 2 are sensitive and selective sensors for detection of cyanide over all other anions SCN−, AcO−, N3−, H2PO4−, H2AsO4−, F−, Cl−, Br−, and I− in aqueous media. Cyanide induces colorimetric change from pale yellow to dark yellow and from transparent to pale yellow for 1 and 2, respectively. It enhances the absorption at wavelengths 385 nm and 425 nm of 1 and 385 nm and 435 nm of 2. Acidic anions H2PO4− and H2AsO4− displayed significant interference with the interaction of cyanide and sensors 1 and 2. Sensor 1 has lower detection limit (LDL) 1 × 10−6 M, while 2 has LDL 1.35 × 10−6 M

الأحماض الدهنية الفسفوليبيدية في الاسفنجياات التي تنمو في قطر 1 - هالوسكاليدا

The phospholipid fatty acid contents of six Haplosclerida sponges collected along Qatari ;ts, Arabian Gulf, were identified by coupling GC-MS experiments. More than hundred of rated and unsaturated fatty acids have been identified. Strong variations were observed for both rated and unsaturated fatty acids within the three studied genera: Callyspongia, Gelliodes, and tates. A new dienoic fatty acid: 14-Me-5,9-17:2 and several rare or uncommon fatty acids were tified from GC/MS coupling experiments. Striking differences between both Gelliodes species e observed for fatty acids belonging to the n-7 family with total content ranging from 0 to 18%.تم التعرف على الأحماض الدهنية الفسفوليبيدية لستة أنواع من اسفنج هالوسكاليدا الذي ينمو في قطر باستخدام كروماتوجرافيا الغاز وطيف الكتلة. وتم فصل أكثر من مائة حمض دهني مشبع وغير مشبع. وأوضحت الدراسة وجود فارق كبير في بنية الأحماض الدهنية المشبعة وغير المشبعة بين ثلاثة فصائل هي: كاليسبونجيا و جليوديس ونيفاتس كما تم التعرف على حمض دايانويك جديد 14-Me-5, 9-7 وبعض الأحماض الدهنية النادرة. كما أن الدراسة أوضحت اختلاف واضح في مكونات الأحماض الدهنية التي تنتمي إلى عائلة n-7 لأسفنج جليوديس حيث تراوحت نسبتها من صفر إلى 18%