Molecular networking-assisted isolation of chlorophenolic glycosides from the rhizomes of Curculigo orchioides and their inhibitory effect on α-glucosidase.

Molecular networking analysis and in silico tools, such as Network Annotation Propagation (NAP) and MolNetEnhancer, were applied to explore bioactive constituents present in the ethyl acetate-soluble fraction of the rhizomes of Curculigo orchioides. Among the molecular networks, the most abundant cluster was classified as a phenolic glycoside using the ClassyFire module of MolNetEnhancer. Further, the major node in this cluster was accurately predicted as curculigine A using the in silico fragment analysis tool, NAP. Six undescribed chlorophenolic glycosides (1-6) and 11 known phenolic glycosides were isolated, using molecular networking-assisted isolation methods, and their structures were elucidated using 1D, 2D-NMR and HRESIMS. In particular, the structures of the isolated chlorophenolic glycosides, which have non-protonated aromatic rings, were determined using various NMR experiments, such as 1D-selective NOE, ROESY, and LR-HMBC, and acid hydrolysis. All isolated compounds were examined to determine their inhibitory effects on α-glucosidase and compounds 3, 8, 10, 11, 13, 14, and 16 revealed the IC50 values ranging from 19.6 to 35.5 µM. Their structure-activity relationships were also evaluated based on the analysis of their inhibitory effects and performance of molecular docking simulations.

Molecular Networking-Guided Isolation of Cycloartane-type Triterpenoids from Curculigo orchioides and Their Inhibitory Effect on Nitric Oxide Production.

The MolNetEnhancer workflow was applied to molecular networking analysis of the CH2Cl2-soluble fraction of the rhizomes of Curculigo orchioides, which showed a potent inhibitory effect on the lipopolysaccharide (LPS)-induced nitric oxide production. Among the molecular network, clusters of cycloartane-type triterpenoids were classified using the ClassyFire module of MolNetEnhancer, and their structures were predicted by the in silico fragment analysis tool, Network Annotation Propagation (NAP). Using mass spectrometry (MS)-guided isolation methods, six cycloartane-type triterpenoids (1-6) were isolated, and their structures were elucidated based on the interpretation of NMR, HRESIMS, and single-crystal X-ray diffraction. Among the isolates, compounds 1 and 4, which have an α,ß-unsaturated carbonyl moiety on the A-ring, exhibited significant inhibitory effects on LPS-induced nitric oxide production in RAW264.7 cells with IC50 values of 12.4 and 11.8 µM, respectively.

Bioactive molecular network-guided discovery of dihydro-ß-agarofurans from the fruits of Celastrus orbiculatus.

A bioactive molecular networking strategy has been applied to discovery of bioactive constituents from the fruits of Celastrus orbiculatus Thunb., which showed significant inhibitory effects on the α-MSH-induced melanin production in B16F0 melanoma cells. In the obtained molecular network, the nodes with relatively high bioactive scores were prioritized for isolation; as a result, 12 undescribed dihydro-ß-agarofuran sesquiterpenes together with 15 known compounds were isolated from MeOH extracts of the fruits of C. orbiculatus. Their structures were elucidated based on the interpretation of NMR, HRESIMS, ECD data, and single crystal X-ray diffraction. Among the obtained isolates, celastorbin A and (1R,2S,4R,5S,7S,8S,9R,10S)-1,2,8-triacetoxy-9-cinnamoyloxydihydro-ß-agarofuran, which possessed high bioactive scores in the molecular network, exhibited potent inhibitory effects on the α-MSH-induced melanin production in B16F0 cells with IC50 values of 4.1 and 2.0 µM, respectively.

Polyacetylenes from the roots of Cirsium japonicum var. ussuriense.

Eight previously undescribed polyacetylenes, cirussurynes A-H, were isolated from the methanolic extract of the roots of Cirsium japonicum var. ussuriense. Their structures were elucidated by interpretation of extensive 1D and 2D NMR spectroscopy and HRESIMS spectrometry data. The configuration of triols in cirussurynes A, B, and E-G was deduced by the J-value based configuration analysis together with specific rotation values. All compounds were evaluated for their inhibitory effects on nitric oxide production against LPS-induced RAW 264.7 macrophages, and exhibited IC50 values ranging from 5.5 to 68.7 µM.

Chemical constituents from Pterocarpus santalinus and their inhibitory effects on nitric oxide production.

A tropolone (2) and an acorane sesquiterpene (3), along with twenty previously known compounds were isolated from the heartwood of Pterocarpus santalinus. The structure of the isolated compounds was elucidated via 1D and 2D NMR spectroscopy and HRESIMS analysis. The absolute configuration of 3 was determined by comparison of the experimental and calculated ECD data. All compounds were evaluated for their inhibitory effects against nitric oxide production in LPS-stimulated RAW 264.7 macrophages.

Sesquiterpenoids from Chrysanthemum indicum with Inhibitory Effects on NO Production.

Three new guaianolide lactones (1-3) and four new 9-oxonerolidol glucosides (5-8) together with 20 known compounds were isolated from the MeOH extract of the flowers of Chrysanthemum indicum. Their structures were elucidated based on the interpretation of NMR, HRESIMS, and electronic circular dichroism (ECD) data along with acid hydrolysis. Of the isolates, sesquiterpenoids 1-4 and 15 and flavones 17 and 18 exhibited inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide production in RAW 264.7 cells with IC50 values in the range 0.2-27.0 µM.

Pentacyclic triterpenes with nitric oxide inhibitory activity from Potentilla chinensis.

Three new ursane-type triterpenes (1-3) and twenty-one known triterpenoids (4-24) were isolated from the methanolic extract of the whole plants of Potentilla chinensis. Their structures were elucidated by extensive spectroscopic analysis of 1D and 2D NMR (HSQC, HMBC, COSY and ROESY) and HRESIMS data. The bioassay screening revealed the inhibitory effects on nitric oxide production of compounds 2, 5, 7, 9, 10, and 13-24 in LPS-induced RAW264.7 macrophages.

Diterpenoids and Diacetylenes from the Roots of Aralia cordata with Inhibitory Effects on Nitric Oxide Production.

Bioactivity-guided isolation of a MeOH extract of Aralia cordata led to the isolation of four new ent-pimarane diterpenoids (1-4) and a diacetylene (5) together with 21 known compounds (6-26). Their structures were established based on the interpretation of one- and two-dimensional NMR and HRESIMS data. The absolute configurations of the new isolates were determined by electronic circular dichroism data analysis, single crystal X-ray diffraction, and Mosher's esterification method. All compounds exhibited inhibitory effects on lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophages with IC50 values ranging from 1.1 to 69.4 µM.

Pyranoflavanones and Pyranochalcones from the Fruits of Amomum tsao-ko.

Eight new geranylated and farnesylated pyranoflavanones (1-8) and two new farnesylated pyranochalcones (9 and 10) were isolated from the methanolic extract of the fruits of Amomum tsao-ko. Their structures were elucidated by extensive analysis of the 1D and 2D NMR spectra and from the HRESIMS, combined with experimental ECD data. All compounds were evaluated for their inhibitory effects on the nitric oxide production against lipopolysaccharide-induced RAW 264.7 macrophages and exhibited IC50 values ranging from 10.6 to 41.5 µM.

Phenolic amides from Tribulus terrestris and their inhibitory effects on nitric oxide production in RAW 264.7 cells.

A new phenolic amide, named cis-terrestriamide (7), together with ten known compounds (1-6, 8-11), were isolated from the methanolic extract of the fruits of Tribulus terrestris. The structure of 7 was elucidated on the basis of extensive analyses of 1D and 2D nuclear magnetic resonance spectroscopic and high resolution mass spectrometry data. Compounds 1, 2, 5, 6, 8, 9, and 11 exhibited inhibitory effects on the lipopolysaccharide-stimulated nitric oxide production in RAW 264.7 cells, with IC50 values of 18.7-49.4 µM.