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Tetrazole cycle is a promising pharmacophore fragment frequently used in the development of novel drugs. This moiety is a stable, practically non-metabolized bioisosteric analog of carboxylic, cis-amide, and other functional groups. Over recent 10-15 years, various isomeric forms of tetrazole (NH-unsubstituted, 1H-1- substituted, and 2H-2-substituted tetrazoles) have been successfully used in the design of promising anticancer drugs. Coordination compounds of transition metals containing tetrazoles as ligands, semisynthetic tetrazolyl derivatives of natural compounds (biogenic acids, peptides, steroids, combretastatin, etc.), 5-oxo and 5- thiotetrazoles, and some other related compounds have been recognized as promising antineoplastic agents. This review presents a comprehensive analysis of modern approaches to synthesis of these tetrazole derivatives as well as their biological (anticancer) properties. The most promising structure types of tetrazoles to be used as anticancer agents have been picked out.

The tetrazole ring is an important pharmacophore. It is a structural component in many drugs, drug candidates (or lead compounds) and various biochemical reagents. This review summarizes data on the use of tetrazoles in biomedicine published in the last 10 – 15 years and also views on the nature of their biological effects. The prospects for the development of new biologically active substances containing a tetrazolyl pharmacophore are analyzed. The bibliography includes 263 references.

The principal methods of synthesis of tetrazole-containing coordination complexes are systematized and generalized.

ABSTRACT:In situ plankton sampling, combined with remotely sensed and ocean Seaglider observations, provided insight into the termination of the winter monsoon bloom and subsequent evolution into a subsurface fluorescence maximum in the northwestern Arabian Sea. This subsurface maximum gradually descended, presenting increased fluorescence between 25 and 55 m depth during the spring inter-monsoon season. Species diversity decreased by half within the deep fluorescence maximum relative to the bloom. The dinoflagellate Noctiluca scintillans dominated by biomass in all samples collected from the depth of the subsurface fluorescence maximum. We show that the subsurface algal bloom persists throughout inter-monsoon seasons, linking algal blooms initiated during the southwest and northeast monsoons. In situ samples showed a net decrease in Noctiluca cell size, illustrating a shift towards a deep chlorophyll maximum adapted community, but did not exhibit any increases in chlorophyll-containing endosymbionts. We propose that the plankton biomass and estimates of the northwestern Arabian Sea productivity are much greater than estimated previously through remote sensing observations, due to the persistence, intensity and vertical extent of the deep chlorophyll maximum whichusing remote means -can only be estimated, but not measured.

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A series of tris(5‐aryl‐1H‐tetrazol‐1‐yl)methanes (3a‐3g) and 2‐dichloromethyl‐5‐aryl‐2H‐tetrazoles (4a‐4d) were synthesized by reaction of 5‐aryl‐NH‐tetrazoles with trichloromethane in strong aqueous basic condition. The compounds obtained were fully characterized by means of HRESI‐MS, 1H and 13C{1H} NMR spectroscopies, as well as by single‐crystal X‐ray diffraction (for 3a, 3b, 4d). Inspection of the X‐ray diffraction data and Hirshfeld surface analysis for tris(5‐aryl‐1H‐tetrazol‐1‐yl)methanes 3a,b and 2‐dichloromethyl‐5‐aryl‐2H‐tetrazole 4d showed the presence of noncovalent π‐hole•••lone pair and π‐hole•••π interactions involving electrophilic tetrazole carbon atom.