Chemical analysis of amyloid ß aggregation inhibitors derived from Geranium thunbergii.

Amyloid ß (Aß) aggregates in the brains of patients with Alzheimer's disease (AD) and accumulates via oligomerization and subsequent fiber elongation processes. These toxicity-induced neuronal damage and shedding processes advance AD progression. Therefore, Aß aggregation-inhibiting substances may contribute to the prevention and treatment of AD. We screened for Aß42 aggregation inhibitory activity using various plant extracts and compounds, and found high activity for a Geranium thunbergii extract (EC50 = 18 µg/mL). Therefore, we screened for Aß42 aggregation inhibitors among components of a G. thunbergii extract and investigated their chemical properties in this study. An active substance was isolated from the ethanol extract of G. thunbergii based on the Aß42 aggregation inhibitory activity as an index, and the compound was identified as geraniin (1) based on spectral data. However, although geraniin showed in vitro aggregation-inhibition activity, no binding to Aß42 was observed via saturation transfer difference-nuclear magnetic resonance (STD-NMR). In contrast, the hydrolysates gallic acid (2) and corilagin (5) showed aggregation-inhibiting activity and binding was observed via STD-NMR. Therefore, the hydrolysates produced under the conditions of the activity test may contribute to the Aß42 aggregation-inhibition activity of G. thunbergii extracts. Geraniin derivatives may help prevent and treat AD.

Simple amino silyl ether organocatalyst for asymmetric hetero Diels-Alder reaction of isatins with enones.

New two catalysts component system comprising of a primary ß-amino silyl ethers as an organocatalyst and N-protected amino acids as a co-catalyst put together worked as an efficient organocatalyst system in the hetero Diels-Alder reaction of isatins with enones affording the chiral spirooxindole-tetrahydropyranones in good chemical yields and stereoselectivities (up to 94%, up to dr 78:22., up to 85% ee).

Enantioselective Diels-Alder reaction of 1,2-dihydropyridines with aldehydes using ß-amino alcohol organocatalyst.

The enantioselective Diels-Alder reaction of 1,2-dihydropyridines with aldehydes using an easily prepared optically active ß-amino alcohol catalyst was found to provide optically active isoquinuclidines, an efficient synthetic intermediate of pharmaceutically important compounds such as oseltamivir phosphate, with a satisfactory chemical yield and enantioselectivity (up to 96%, up to 98% ee). In addition, the obtained highly optically pure isoquinuclidine was easily converted to an optically active piperidine having four successive carbon centers.

Characterization of Ralstonia insidiosa C1 isolated from Alpine regions: Capability in polyhydroxyalkanoates degradation and production.

This study ventures into the exploration of potential poly-3-hydroxybutyrate (PHB) degradation in alpine environments. PHB-degrading bacteria were identified in both campus soil, representing a residential area, and Mt. Kurodake soil, an alpine region in Hokkaido, Japan. Next-generation sequencing analysis indicated that the campus soil exhibited higher microbial diversity, while Ralstonia insidiosa C1, isolated from Mt. Kurodake soil, displayed the highest proficiency in PHB degradation. R. insidiosa C1 efficiently degraded up to 3% (w/v) of PHB and various films composed of other biopolymers at 14 °C. This bacterium synthesized homopolymers using substrates such as 3-hydroxybutyric acid, sugars, and acetic acid, while also produced copolymers using a mixture of fatty acids. The analysis results confirmed that the biopolymer synthesized by strain C1 using glucose was PHB, with physical properties comparable to commercial products. The unique capabilities of R. insidiosa C1, encompassing both the production and degradation of bioplastics, highlight its potential to establish a novel material circulation model.

New boro amino amide organocatalysts for asymmetric cross aldol reaction of ketones with carbonyl compounds.

Distinct types of new boron fused primary amino amide organocatalysts were designed and synthesized from commercially available amino acids. Their catalytic activities were investigated in asymmetric crossed aldol reaction of ketones with aromatic aldehydes to afford the corresponding chiral anti-aldol adducts with good chemical yields, moderate diastereoselectivity and good to excellent enantioselectivities (up to 94% yields, up to 90 : 10 dr, up to 94% ee).

Thiourea fused γ-amino alcohol organocatalysts for asymmetric Mannich reaction of ß-keto active methylene compounds with imines.

Catalytic functionality of new optically active thiourea fused γ-amino alcohols was examined in the asymmetric Mannich reaction of ß-keto active methylene compounds with imines to afford chiral Mannich products, ß-amino keto compounds, with continuous chiral centers, that are versatile synthetic intermediates for deriving various biologically active compounds. In particular, the thiourea fused γ-amino alcohols showed satisfactory catalytic activity in this reaction and afforded chiral Mannich products in excellent chemical yield (up to 88%) and stereoselectivities (up to syn : anti/93 : 7 dr, up to 99% ee).

New small γ-turn type N-primary amino terminal tripeptide organocatalyst for solvent-free asymmetric aldol reaction of various ketones with aldehydes.

New small γ-turn type N-primary amino terminal tripeptides were synthesized and their functionality as an organocatalyst was examined in the asymmetric aldol reaction of various ketones with different aromatic aldehydes under solvent-free neat conditions to afford the desired chiral anti-aldol products in good to excellent chemical yields, diastereoselectivities and enantioselectivities (up to 99%, up to syn : anti/13 : 87 dr, up to 99% ee).

Simple primary ß-amino alcohols as organocatalysts for the asymmetric Michael addition of ß-keto esters to nitroalkenes.

Simple primary ß-amino alcohols act as an efficient organocatalysts in the asymmetric Michael addition of ß-keto esters with nitroalkenes affording highly pure chiral Michael adducts. Also, both enantiomers of the adducts were obtained, depending on the specific catalyst used and reaction temperature.

Simple organocatalyst component system for asymmetric hetero Diels-Alder reaction of isatins with enones.

A simple two catalyst component system consisting of primary ß-amino alcohols as a catalyst and amino acids as a co-catalyst put together works as an efficient organocatalyst system in the hetero Diels-Alder reaction of isatins with enones to afford the chiral spirooxindole-tetrahydropyranones in good chemical yields and stereoselectivities (up to 86%, up to 85 : 15 dr., up to 95% ee).

New Hybrid-type Squaramide-Fused Amino Alcohol Organocatalyst for Enantioselective Domino Michael Addition/Cyclization Reaction of Oxoindolines with Cyclic 1,3-Diketones.

The new hybrid-type squaramide-fused amino alcohol containing both a Brønsted basic site and hydrogen-bonding sites in the molecule showed a high catalytic activity as an organocatalyst in the enantioselective domino Michael addition/cyclization reaction of oxoindolines with cyclic 1,3-diketones to afford the chiral spiro-conjugated oxindoles featuring 2-aminopyrans fusing with carbo-heterocyclic ring systems with excellent chemical yields (up to 98%) and enantioselectivities (up to 95% ee). The obtained chiral spiro-conjugated 2-aminopyrans bearing quaternary stereogenic carbon center could be used as synthetic precursors for several natural products that have a broad spectrum of fascinating biological activities.

Structure-activity relations of rosmarinic acid derivatives for the amyloid ß aggregation inhibition and antioxidant properties.

Amyloid-ß aggregation inhibitors are expected to be therapeutic or prophylactic agents for Alzheimer's disease. Rosmarinic acid, which is one of the main aggregation inhibitors derived from Lamiaceae, was employed as a lead compound and its 25 derivatives were synthesized. In this study, the structure-activity relations of rosmarinic acid derivatives for the amyloid-ß aggregation inhibitory effect (MSHTS assay), antioxidant properties, and xanthine oxidase inhibition were evaluated. Among the tested compounds, compounds 16d and 19 were found to the most potent amyloid aggregation inhibitors. The SAR revealed that the necessity of the presence of the phenolic hydroxyl on one side of the molecule as well as the lipophilicity of the entire molecule. The importance of these structural properties was also supported by docking simulations.

Poly-3-hydroxybutyrate (PHB) production from alkylphenols, mono and poly-aromatic hydrocarbons using Bacillus sp. CYR1: A new strategy for wealth from waste.

In the present study five different types of alkylphenols, each of the two different types of mono and poly-aromatic hydrocarbons were selected for degradation, and conversion into poly-3-hydroxybutyrate (PHB) using the Bacillus sp. CYR1. Strain CYR1 showed growth with various toxic organic compounds. Degradation pattern of all the organic compounds at 100 mg/l concentration with or without addition of tween-80 were analyzed using high pressure liquid chromatography (HPLC). Strain CYR1 showed good removal of compounds in the presence of tween-80 within 3 days, but it took 6 days without addition of tween-80. Strain CYR1 showed highest PHB production with phenol (51 ± 5%), naphthalene (42 ± 4%), 4-chlorophenol (32 ± 3%) and 4-nonylphenol (29 ± 3%). The functional groups, structure, and thermal properties of the produced PHB were analyzed. These results denoted that the strain Bacillus sp. CYR1 can be used for conversion of different toxic compounds persistent in wastewaters into useable biological polyesters.

A novel chiral oxazolidine organocatalyst for the synthesis of an oseltamivir intermediate using a highly enantioselective Diels-Alder reaction of 1,2-dihydropyridine.

Enantioselective Diels-Alder reactions of 1,2-dihydropyridines with acroleins using a novel chiral oxazolidine organocatalyst afforded chiral isoquinuclidines that is an efficient synthetic intermediate of oseltamivir, with fairly good chemical yield and excellent enantioselectivity (90%, up to >99% ee).