Current Bioactive Compounds - Volume 9, Issue 2, 2013

Fungi are far more complex organisms than viruses or bacteria and can develop numerous diseases in plants that cause loss of big portion of the crop every year. Another important aspect is that many filamentous fungi are destructive human pathogens and are thus responsible for enormous diseases in humans. A series of molecules with antifungal activity against different strains of fungi have been found in plants, which are of great importance to humans. Plants have developed various mechanisms to defend themselves against these fungi which include the production of low molecular weight secondary metabolites, proteins and peptides having antifungal activity. In this review, brief information like structure, source, mode of action of defense mechanism and their promising contribution in the field of medicine and agriculture is discussed. These molecules may be used directly or considered as a precursor for developing molecules with better therapeutic values. This review attempts to summarize the current status of important antifungal proteins from various natural occurring sources like plants, bacteria and insects.

Enantiomerically pure product synthesis plays a key role in production of pharmaceuticals. The application of biocatalytic approaches represents a convenient and sustainable way for this purpose. The enormous potential of enzymes for the transformation of synthetic chemicals with high chemo-, regio- and enantioselectivity is on increasing awareness. In particular, lipases show a high versatility to recognize non-natural substrates being successfully applied in regio- and stereoselective biotransformations. The immobilization technology on lipases is not only a requisite for the industrial implementation but it has been a great methodology to alter their catalytic properties to obtain highly enantio- and regioselective biocatalysts in the enantioselective synthesis of chiral drugs or drug intermediates. This review focuses on showing some of the latest advances on the use of immobilized lipases on pharmaceutical biotransformations.

The aim of this work is to obtain the bioactive compounds in hydroalcoholic extracts of hawthorn (Crataegus oxyacantha, Fam. Rosaceae), chokeberry (Aronia melanocarpa, Fam. Rosaceae), rosehip (Rosa canina, Fam. Roseaceae) and bilberry (Vaccinium myrtillus L., Fam. Ericaceae) by means of membrane separation process. Fruit extracts were processed by microfiltration at ambient temperature and the bioactive compounds were subsequently characterized. The microfiltration of plant extracts led to the concentration of biologically active compounds including polyphenols, procyanidins, flavanols, and their separation from lower molecular weight compounds (amino acids, monosaccharides etc.), passed into the microfiltration permeate solutions. To investigate the antioxidant activity of each plant extract, cupric ion reduction antioxidant capacity (CUPRAC) spectrophotometric methodology was employed.

Serotonin is a monoamine neurotransmitter and biochemically derived from tryptophan. The present paper examines the in vitro antioxidant and radical scavenging capacity of serotonin using different in vitro methodologies. For the determination of antioxidant activity of serotonin, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH-) scavenging, 2,2´- azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, total antioxidant activity determination by ferric thiocyanate, total reducing ability determination by Fe3+-Fe2+ transformation method, superoxide anion radical scavenging by riboflavin-methionine-illuminate system, H2O2 scavenging and ferrous ions (Fe2+) chelating activities of serotonin were performed. Also, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol and trolox, a water-soluble analog of α-tocopherol, were used as the reference antioxidant radical scavenger compounds. Serotonin completely inhibited lipid peroxidation of a linoleic acid emulsion at 15 µg/mL concentration. On the other hand, the above mentioned standard antioxidants displayed inhibition of 92.2, 99.6, 84.6 and 95.6% on peroxidation of linoleic acid emulsion, respectively at the 45 µg/mL concentration. In addition, serotonin was effective in DPPH- scavenging, ABTS•+ radical scavenging, superoxide anion radical scavenging, H2O2 scavenging, ferric ions (Fe3+) reducing power and metal chelating on ferrous ions (Fe2+) activities. Also, those various antioxidant activities were compared to BHA, BHT α-tocopherol and trolox as references antioxidant compounds.

Toxoplasma gondii (T. gondii) is the most common cause of secondary central nervous system infection in immunocompromised persons such as AIDS patients. Dihydrofolate reductase and thymidylate synthase enzymes have been studied as attractive targets against parasitic diseases, since they are involved in cell proliferation and influence on DNA synthesis. In this paper, we propose three-dimensional structures of T. gondii dihydrofolate reductase and thymidylate synthase based on homology modeling. In addition, we assessed the interaction mode of pyrimidine analogs in the active site of T. gondii and human enzymes, in order to direct the planning of new compounds that can be used against toxoplasmosis. According to the docking studies, predicted pIC50 values for proposed compounds were higher than those of the experimentally most active compound.

A new and efficient method for the preparation of 3-amino-6-thieno[2,3-b]pyridine-2-carbohydrazides and pyrido[3',2':4,5]thieno[3,2-d]pyramidinones from one-pot synthesis has been accomplished using 3-amino-6-thieno[2,3- b]pyridines with hydrazine hydrate in ethanol under reflux. This new protocol has the advantages of easy availability and high to excellent yields, simple experimental and work-up procedure. The synthesized compounds were confirmed through spectral characterization using IR, 1H NMR, mass spectra and elemental analyses.