Conformational studies on l-amino-l-deoxypentitols

Pyrrole-2-carbaldehydes with neuroprotective activities from Moringa oleifera seeds

Seven undescribed pyrrole-2-carbaldehydes (pyrrolemorines A-G), along with four known analogs, were isolated from the aqueous extract of Moringa oleifera seeds. The structures were elucidated by comprehensive spectroscopic and chemical analyses using HRMS and NMR spectra, acid hydrolysis, and Rh2(OCOCF3)4-induced ECD experiments. Pyrrolemorines A, E, and pyrrolemarumine displayed neuroprotective activities against oxygen-glucose deprivation/reperfusion injury in PC12 cells by regulating NF-κb and Nrf2.

Four undescribed sulfur-containing indole alkaloids with nitric oxide inhibitory activities from Isatis tinctoria L. roots

Four undescribed sulfur-containing indole alkaloids, isatisindigoticanines H, I and isatindigosides F, G along with three known analogues were obtained from Isatis tinctoria L. roots. Isatisindigoticanines H and I contained an unusual 1-(thiazol-4-yl)butane-1,2,3,4-tetraol moiety while isatindigosides F and G possessed a new 3-[3-(1H-indole-2-yl)azet-2-yl]-1H-indole skeleton. The putative biosynthetic pathways of isatisindigoticanines H, I and isatindigosides F, G are proposed. The isolated compounds showed nitric oxide inhibitory effects with IC₅₀ values ranging from 4.3 to 70.3 μM.

Isatisindigoticanine A, a novel indole alkaloid with an unpresented carbon skeleton from the roots of Isatis tinctoria

Isatisindigoticanine A (1), a new indole alkaloid with an unusual carbon skeleton of a benzofuran-3-one unit connected with a 1H-indole-3-yl unit and a 4-(1,2-dihydroxyethyl)-6-oxa-3-azabicyclo[3.1.0]hexan-2-one unit via a C-3－C-8'' bond and a C-4'－C-8'' bond, was obtained from the roots of Isatis tinctoria. Its structure was determined by physicochemical properties and spectroscopic methods including 1 D, 2 D NMR, IR, HRESIMS data. The absolutely configurations were deduced by comparison of its experimental CD and calculated ECD spectra. Nitric oxide (NO) inhibitory activities of isatisindigoticanine A was also evaluated in the LPS-stimulated RAW 264.7 cells, however, no inhibitory effect was presented.

Dihydroxyacetone variants in the organocatalytic construction of carbohydrates: mimicking tagatose and fuculose aldolases

Dihydroxyacetone variants have been explored as donors in organocatalytic aldol reactions with various aldehyde and ketone acceptors. The protected form of dihydroxyacetone that was chosen for in-depth study was 2,2-dimethyl-1,3-dioxan-5-one, 1. Among the catalysts surveyed here, proline proved to be superior in terms of yield and stereoselectivities in the construction of various carbohydrate scaffolds. In a fashion analogous to aldolase enzymes, the de novo preparation of L-ribulose, L-lyxose, D-ribose, D-tagatose, 1-amino-1-deoxy-D-lyxitol, and other carbohydrates was accomplished via the use of 1 and proline. In reactions using 2,2-dimethyl-1,3-dioxan-5-one 1 as a donor, (S)-proline can be used as a functional mimic of tagatose aldolase, whereas (R)-proline can be regarded as an organocatalytic mimic of fuculose aldolase.

Mimicking Dihydroxy Acetone Phosphate-Utilizing Aldolases through Organocatalysis: A Facile Route to Carbohydrates and Aminosugars

[reaction: see text] A practical and environmentally friendly organocatalytic strategy designed to mimic the DHAP aldolases has been developed and shown to be effective in the preparation of carbohydrates and aminosugars. (S)-Proline and (S)-2-pyrrolidine-tetrazole catalyzed the aldol reaction between dihydroxy acetone variants such as 1,3-dioxan-5-one and 2,2-dimethyl-1,3-dioxan-5-one with aldehydes to give the corresponding polyols in good yields with very high ees.