Synthesis, biological evaluation, and molecular modeling of nitrile-containing compounds: Exploring multiple activities as anti-Alzheimer agents.

Based on the monoamine oxidase (MAO) inhibition properties of aminoheterocycles with a carbonitrile group we have carried out a systematic exploration to discover new classes of carbonitriles endowed with dual MAO and AChE inhibitory activities, and Aß anti-aggregating properties. Eighty-three nitrile-containing compounds, 13 of which are new, were synthesized and evaluated. in vitro screening revealed that 31, a new compound, presented the best lead for trifunctional inhibition against MAO A (0.34 µM), MAO B (0.26 µM), and AChE (52 µM), while 32 exhibited a lead for selective MAO A (0.12 µM) inhibition coupled to AChE (48 µM) inhibition. Computational analysis revealed that the malononitrile group can find an advantageous position with the aromatic cleft and FAD of MAO A or MAO B. However, the total binding energy can be handicapped by an internal penalty caused by twisting of the ligand molecule and subsequent disruption of the conjugation (32 in MAO B compared to the conjugated 31). Conjugation is also important for AChE as well as the hydrophilic character of malononitrile that allows this group to be in close contact with the aqueous environment as seen for 83. Although the effect of 31 and 32 against Aß1-42 , was very weak, the effect of 63 and 65, and of the new compound 75, indicated that these compounds were able to disaggregate Aß1-42 fibrils. The most effective was 63, a (phenylhydrazinylidene)propanedinitrile derivative that also inhibited MAO A (1.65 µM), making it a potential lead for Alzheimer's disease application.

Stereochemical and Steric Control of Photophysical and Chiroptical Properties in Bichromophoric Systems.

Stereochemical and steric control of the relative spatial arrangement of the chromophoric units in multichromophoric systems offers an interesting strategy for raising unusual and appealing light-induced emission states. To explore and exploit this strategy, a series of conformationally restricted boron-dipyrromethene (BODIPY) dimers were designed by using tartaric acid as a symmetrical connector between the boron atoms of the dyes. The variety of stereoisomeric forms available for this bis(hydroxy acid) allows the relative spatial orientation of the chromophoric units in the dimer to be modified, which thus opens the door to modulation of the photophysical and chiroptical properties of the new bichromophoric systems. Chromophore alkylation introduces an additional level of control through distance-dependent steric interactions between the BODIPY units in the dimer, which also modulates their relative spatial disposition and properties.

Synthesis and structural characterization of raffinosyl-oligofructosides upon transfructosylation by Lactobacillus gasseri DSM 20604 inulosucrase.

A new process based on enzymatic synthesis of a series of raffinose-derived oligosaccharides or raffinosyl-oligofructosides (RFOS) with degree of polymerization (DP) from 4 to 8 was developed in the presence of raffinose. This process involves a transfructosylation reaction catalyzed by an inulosucrase from Lactobacillus gasseri DSM 20604 (IS). The main synthesized RFOS were structurally characterized by nuclear magnetic resonance (NMR). According to the elucidated structures, RFOS consist of ß-2,1-linked fructose unit(s) to raffinose: α-D-galactopyranosyl-(1 → 6)-α-D-glucopyranosyl-(1↔2)-ß-D-fructofuranosyl-((1 ← 2)-ß-D-fructofuranoside)n (where n refers to the number of transferred fructose moieties). The maximum yield of RFOS was 33.4 % (in weight respect to the initial amount of raffinose) and was obtained at the time interval of 8-24 h of transfructosylation reaction initiated with 50 % (w/v) of raffinose. Results revealed the high acceptor and donor affinity of IS towards raffinose, being fairly comparable with that of sucrose for the production of fructooligosaccharides (FOS), including when both carbohydrates coexisted (sucrose/raffinose mixture, 250 g L(-1) each). The production of RFOS was also attempted in the presence of sucrose/melibiose mixtures; in this case, the predominant acceptor-product formed was raffinose followed by a minor production of a series of oligosaccharides with varying DP. The easiness of RFOS synthesis and the structural similarities with both raffinose and fructan series of oligosaccharides warrant the further study of the potential bioactive properties of these unexplored oligosaccharides.

A new Delta7,22 sterol from the bulbs of Autonoë madeirensis.

The spectral data of a new Delta7,22 sterol, 24S-ethyl-5alpha-cholesta-7,22E-dien-3alpha-ol beta-galactopyranoside, isolated from the bulbs of Autonoë madeirensis, are reported.

Synthesis of potentially-bioactive lactosyl-oligofructosides by a novel bi-enzymatic system using bacterial fructansucrases.

Efficient enzymatic synthesis of lactosyl-oligofructosides (LFOS) with a degree of polymerization from 4 to 8 was achieved in the presence of sucrose:lactosucrose and sucrose:lactose mixtures by transfructosylation reaction. The main synthesized LFOS which consist of ß-2,1-linked fructose to lactosucrose: ß-d-galactopyranosyl-(1→4)-α-d-glucopyranosyl-[(1→2)-ß-d-fructofuranosyl]n-(1→2)-ß-d-fructofuranoside (where n refers to the number of transferred fructose moieties) was structurally characterized by nuclear magnetic resonance (NMR). The maximum formation of LFOS was 81% (in weight with respect to the initial amount of lactosucrose) and was obtained after 24h of transfructosylation reaction based on sucrose:lactosucrose (250gL-1 each) catalyzed by an inulosucrase from Lactobacillus gasseri DSM 20604 (IS). The production of LFOS in the presence of sucrose:lactose mixtures required a previous high-yield lactosucrose synthesis step catalyzed by using a levansucrase from Bacillus subtilis CECT 39 (LS) before the inulosucrase-catalyzed reaction. This novel one-pot bi-enzymatic system led to the synthesis of about 22% LFOS in weight, with respect to the initial amount of lactose (250gL-1). The results revealed a high specificity for the substrate involved in the inulosucrase-catalyzed reaction given that, although lactosucrose (O-ß-d-galactopyranosyl-(1→4)-O-α-d-glucopyranosyl-(1→2)-ß-d-fructofuranoside) acted as a strong acceptor of ß-2,1-linked fructose, lactose (ß-d-galactopyranosyl-(1→4)-α-d-glucose) was found to be an extremely weak acceptor.

Synthesis and characterization of a potential prebiotic trisaccharide from cheese whey permeate and sucrose by Leuconostoc mesenteroides dextransucrase.

The production of new bioactive oligosaccharides is currently garnering much attention for their potential use as functional ingredients. This work addresses the enzymatic synthesis and NMR structural characterization of 2-α-D-glucopyranosyl-lactose derived from sucrose:lactose and sucrose:cheese whey permeate mixtures by using a Leuconostoc mesenteroides B-512F dextransucrase. The effect of synthesis conditions, including concentration of substrates, molar ratio of donor/acceptor, enzyme concentration, reaction time, and temperature, on the formation of transfer products is evaluated. Results indicated that cheese whey permeate is a suitable material for the synthesis of 2-α-D-glucopyranosyl-lactose, giving rise to yields around 50% (in weight respect to the initial amount of lactose) under the optimum reaction conditions. According to its structure, this trisaccharide is an excellent candidate for a new prebiotic ingredient, due to the reported high resistance of α-(1→2) linkages to the digestive enzymes in humans and animals, as well as to its potential selective stimulation of beneficial bacteria in the large intestine mainly attributed to the two linked glucose units located at the reducing end that reflects the disaccharide kojibiose (2-α-D-glucopyranosyl-D-glucose). These findings could contribute to broadening the use of important agricultural raw materials, such as sucrose or cheese whey permeates, as renewable substrates for enzymatic synthesis of oligosaccharides of nutritional interest.

New Gly-Pro-Glu (GPE) analogues: expedite solid-phase synthesis and biological activity.

A suitable solid-phase approach, based on Fmoc/(t)Bu methodology and on the use of 2-chlorotrityl resin, allowed a rapid and efficient preparation of new GPE analogues. Most of the synthesized tripeptides displayed glutamate receptor binding affinity comparable to that of GPE, but only a few derivatives showed significant neuroprotective activity.

The neuroprotective activity of GPE tripeptide analogues does not correlate with glutamate receptor binding affinity.

The influence of several modifications on the GPE tripeptide structure upon the binding to GluRs and on their neuroprotective effects has been studied. The results indicated that the prevention of neuronal death showed by GPE and some analogues is not directly related to their affinity at glutamate receptors.

Analogues of the neuroprotective tripeptide Gly-Pro-Glu (GPE): synthesis and structure-activity relationships.

A series of GPE analogues, including modifications at the Pro and/or Glu residues, was prepared and evaluated for their NMDA binding and neuroprotective effects. Main results suggest that the pyrrolidine ring puckering of the Pro residue plays a key role in the biological responses, while the preference for cis or trans rotamers around the Gly-Pro peptide bond is not important.

New 1H-pyrazole-containing polyamine receptors able to complex L-glutamate in water at physiological pH values.

The interaction of the pyrazole-containing macrocyclic receptors 3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1(11,14)]-octacosa-1(27),11,14(28),24-tetraene 1[L1], 13,26-dibenzyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1(1)(1,14)]-octacosa-1(27),11,14(28),24-tetraene 2[L2], 3,9,12,13,16,22,25,26-octaazatricyclo-[22.2.1.1(11,14)]-octacosa-1(27),11,14(28),24-tetraene 3[L3], 6,19-dibenzyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1(11,)(14)]-octacosa-1(27),11,14(28),24-tetraene 4[L4], 6,19-diphenethyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1(11,14)]-octacosa-1(27),11,14(28),24-tetraene 5[L5], and 6,19-dioctyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.1(11,14)]-octacosa-1(27),11,14(28),24-tetraene 6[L6] with l-glutamate in aqueous solution has been studied by potentiometric techniques. The synthesis of receptors 3-6[L3-L6] is described for the first time. The potentiometric results show that 4[L4] containing benzyl groups in the central nitrogens of the polyamine side chains is the receptor displaying the larger interaction at pH 7.4 (Keff = 2.04 x 10(4)). The presence of phenethyl 5[L5] or octyl groups 6[L6] instead of benzyl groups 4[L4] in the central nitrogens of the chains produces a drastic decrease in the stability [Keff = 3.51 x 10(2) (5), Keff = 3.64 x 10(2) (6)]. The studies show the relevance of the central polyaminic nitrogen in the interaction with glutamate. 1[L1] and 2[L2] with secondary nitrogens in this position present significantly larger interactions than 3[L3], which lacks an amino group in the center of the chains. The NMR and modeling studies suggest the important contribution of hydrogen bonding and pi-cation interaction to adduct formation.