Sideritis spp.: uses, chemical composition and pharmacological activities--a review.

An efficient synthetic procedure for the preparation of fused 2,3-dihydrofuran derivatives was developed with the assistance of pyridinium ylide. A sequential one-pot, two-step tandem reaction starting from pyridine, aromatic aldehyde, dimedone, or 4-hydroxycoumarin and alpha-phenacyl bromide or p-nitrobenzyl bromide with triethylamine as catalyst proceeded smoothly in acetonitrile. (1)H NMR spectroscopy and single-crystal analysis demonstrated that the obtained 2,3-dihydrofurans are trans isomers.

Diastereoselective Synthesis of trans-2,3-Dihydrofurans with Pyridinium Ylide Assisted Tandem Reaction

Biolarvicides, based on mosquitocidal toxins of certain strains of Bacillus sphaericus and Bacillus thuringiensis var israelensis H-14 (Bti) are highly effective against mosquito larvae at very low doses and safe to other non-target organisms. During past two decades various biolarvicide formulations produced in India and abroad have been tested at Malaria Research Centre and some formulations have undergone large-scale operational trials. Biolarvicide formulations of B. sphaericus are useful in the control of Culex and certain Anopheles spp, such as An. stephensi and An. subpictus, but not much effective against An. culicifacies and almost ineffective against Aedes aegypti. Repeated application of B. sphaericus in the same habitat, however, results in the development of resistance in larvae of target mosquitoes. In view of its low specificity for An. culicifacies and the potential for resistance in An. stephensi, B. sphaericus has limited prospects for control of malaria vectors. However, with some resistance management, B. sphaericus can still be used against Culex mosquitoes. On the other hand Bti formulations, which have broader spectrum of activity against Aedes, Culex and Anopheles spp, have not shown significant development of resistance in mosquitoes but their activity in field, particularly against surface feeding anopheline larvae is affected by various bioenvironmental factors, thus requiring weekly application in most habitats. To overcome this problem development of slow release formulations and genetically engineered biolarvicides by transplanting mosquitocidal toxin genes of Bti and B. sphaericus in some other environmentally compatible organisms have been investigated by different scientists.

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Biolarvicides in vector control: challenges and prospects.

The preceding four decades have witnessed a major expansion in the field of free-radical assisted reactions, as they are becoming a key tool in organic, polymer and complex natural product chemistry. This progress has clearly changed the traditional idea of free-radical reactions being “extremely uncontrollable”, thereby allowing chemists to deal with free radicals in a more accurate and controlled way. Manganese(III) acetate mediated radical reactions have reached distinction in this field, as a wide range of protocols involving manganese(III) acetate under mild and efficient reaction conditions have been developed for the synthesis of biologically active and important organic molecules through oxidation, addition and cyclization reactions, which are in general difficult to achieve by the established synthetic operations. The present review focuses on manganese(III) acetate mediated oxidative free-radical reactions that have been developed and adapted during the last five years. It includes the advancements made in the field of free-radical promoted carbon–carbon and carbon–oxygen bond forming reactions, illustrating the examples of furans, hydrofurans, pyrroles, bicyclic lactones, biaryls, oxepins, indole-alkaloids, 1,2-benzanthracene and C60-fused tetrahydronaphthalene synthesis. Numerous manganese(III) acetate initiated carbon–phosphorus bond formation reactions were also devised during recent years, involving both phosphonyl and phosphinoyl radicals, and are a key part of this review. Manganese(III) acetate promotes functionalization of significant organic compounds, thereby guiding the synthesis of important and complex molecules, such as the formation of propellanes, quinolinones, 1,2-dioxalanes; oxidation of indoles; lactonization of fullerene [C60], malonyl cyclopentanes, glycols; and hydroperoxidation of heterocycles. The review will also envelop several recent milestones that have been achieved in the chemistry of natural products precising the vital role of manganese(III) acetate in the key synthetic steps.

Recent advances in manganese(iii) acetate mediated organic synthesis

Selective formation of spiro dihydrofurans and cyclopropanes through unexpected reaction of aldehydes with 1,3-dicarbonyl compounds.

Oxidative cyclization of 3-oxopropanenitriles with α,β-unsaturated amides by manganese(III) acetate. Regio- and stereoselective synthesis of 4-cyano-2,3-dihydrofuran-3-carboxamides

In this work, several diterpenes including siderol, linearol and epicandicandiol were isolated from Sideritis sipylea Boiss collected from Izmir-Karaburun-Akdag, Turkey. In addition, diacetate derivatives of linearol and epicandicandiol were obtained. The antimicrobial activites of all these compounds against the bacteria Staphylococcus aureus (ATTC 25923), Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC 11230), Pseudomonas aeruginosa (ATCC 27853) and the fungus Candida albicans (ATCC 90028) were studied. Antimicrobal activity was measured by the well-diffusion method. Except for C. albicans all microorganisms were tested against antibiotic discs in comparison with the studied compounds. Copyright © 2006 John Wiley & Sons, Ltd.

Biological activities of some natural compounds from Sideritis sipylea Boiss.

The in vitro antibacterial and antifungal activities of the compounds synthesised from some 1,2,3,5-tetrahalogeno benzenes in presence of sodium piperidide and sodium pyrrolidide (2,6-dipiperidino-1,4-dihalogenobenzenes; 2,6-dipyrrolidino-1,4-dibromobenzene; 2,4,6-tripyrrolidino chlorobenzene; and 1,3-dipyrrolidino benzene) were investigated. The in vitro antimicrobial activities were screened against the standard strains: Staphylococcus aureus ATCC 25923 and Bacillus subtilis ATCC 6633 as Gram positive, Yersinia enterocolitica ATCC 1501, Escherichia coli ATCC 11230 and Klebsiella pneumoniae as Gram negative, and Candida albicans as yeast-like fungus. Compounds (3, 5, 6, 7) inhibited the growth of all the test strains at MIC values of 32–512 μg/ml. None of the four compounds (1, 2, 4, 8) studied showed antimicrobial activity against any of the test strains within the MIC range 0.25–512 μg/ml.

Antimicrobial activity studies on some piperidine and pyrrolidine substituted halogenobenzene derivatives

A protease from newly isolated Bacillus circulans M34 was purified by Q-Sepharose anion exchange chromatography and Sepharose–bacitracin affinity chromatography followed by (NH4)2SO4 precipitation. The molecular mass of the purified enzyme was determined using SDS–PAGE. The optimum pH and temperature for protease activity were 11 and 50°C, respectively. The effect of various metal ions on protease activity was investigated. Alkaline protease from Bacillus circulans M34 wase activated by Zn2+, Cu2+ and Co2+ up to 31%. The purified protease was found to be stable in the organic solvents, surfactants and oxidizing agent. The substrate specificity of purified protease was investigated towards different substrates. The protease was almost completely inhibited by the serine protease inhibitor phenylmethanesulfonyl fluoride. The kinetic parameters of the purified protease, maximum rate (Vmax) and Michaelis constant (Km), were determined using a Lineweaver–Burk plot. Copyright © 2015 John Wiley & Sons, Ltd.

Atilla Öktemer

Papers

Oxidative cyclization of 3-oxopropanenitriles with α,β-unsaturated amides by manganese(III) acetate. Regio- and stereoselective synthesis of 4-cyano-2,3-dihydrofuran-3-carboxamides

Biological activities of some natural compounds from Sideritis sipylea Boiss.

Antimicrobial activity studies on some piperidine and pyrrolidine substituted halogenobenzene derivatives

Purification and characterization of organic solvent stable serine alkaline protease from newly isolated Bacillus circulans M34

Larvicidal and sporal behaviour of Bacillus sphaericus 2362 in carrageenan microcapsules