Chemical constituents from the branches and leaves of Alchornea annamica

Isoryanodane diterpene derivatives from Barringtonia macrocarpa

From the MeOH residue of Barringtonia macrocarpa branches and leaves, one new isoryanodane diterpene, barringisol (1), and two new isoryanodane diterpene glucosides, barringisosides A and B (2 and 3), were obtained using various chromatographic isolations. The structural characterization was confirmed by spectroscopic methods including 1D, 2D NMR and HR-ESI-QTOF-MS. This is the first isolation of isoryanodane diterpene derivatives from Barringtonia species. Moreover, the in vitro cytotoxicity of 1-3 on three human cancer cell lines (HepG2, LNCaP and MCF7) was also accessed using SRB assays.

Two new megastigmane glycosides from the leaves of Nicotiana tabacum and their anti-inflammatory activities

Two new megastigmane glycosides, (6 R,7E,9R)-3-oxo-α-ionyl-9-O-α-L-rhamnopyranosyl-(1''→4')-β-D-glucopyranoside (1) and (6 R,7E,9R)-3-oxo-α-ionyl-9-O-β-D-glucopyranosyl-(1''→6')-β-D-glucopyranoside (2), together with six known analogues (3-8) were isolated from the leaves of Nicotiana tabacum. The structures of all metabolites were determined by comprehensive analysis of NMR and MS spectroscopic data as well as by comparison with those of previously reported. The in vitro anti-inflammatory activity of all isolates was evaluated using a lipopolysaccharide (LPS)-induced RAW264.7 cell inflammatory model, and the compounds 1, 3, 7, and 8 exhibited inhibition of LPS-induced NO production in RAW264.7 macrophage cells with IC50 values of 42.3-61.7 μM (positive control, dexamethasone, IC50 = 21.3 ± 1.2 μM).

Unique guanidine-conjugated catechins from the leaves of Alchornea rugosa and their autophagy modulating activity

Natural guanidines, molecules that contain the guanidine moiety, are structurally unique and often exhibit potent biological activities. A phytochemical investigation of the leaves of Alchornea rugosa (Lour.) Müll.Arg. by MS/MS-based molecular networking revealed eight undescribed guanidine-flavanol conjugates named rugonines A-H. The chemical structures of the isolated compounds were comprehensively elucidated by NMR spectroscopy, HRESIMS, and circular dichroism (CD) analysis. All isolated compounds were tested for autophagosome formation in HEK293 cells stably expressing GFP-LC3. The results revealed that compounds rugonines D-G showed potential autophagy inhibitory activity.

Trewioidesine A, an unsaturated fatty acid from rhizomes of Alchornea trewioides, shows synergy with NGF in inducing differentiation of pheochromocytoma PC12 cells

A new unsaturated fatty acid trewioidesine A (1), together with seven known compounds (2 - 8) were isolated from the rhizomes of Alchornea trewioides (Benth.) Muell. Arg. Their structures were established on the basis of extensive spectroscopic data interpretation (1 D and 2 D NMR, and HRESIMS). The absolute configuration of 1 was determined by electronic circular dichroism (ECD) calculations, confirming as trewioidesine A. The functionality of isolated compounds was tested in cultured PC12 cells, a cell line from rat pheochromocytoma. Trewioidesine A was the one showing robust activity in inducing neuronal differentiation: the induction was synergized when co-applied with nerve growth factor (NGF). In addition, a neurofilament 200 (NF200) promoter-luciferase (pNF200-Luc) reporter was used to evaluate the differentiating ability in the transfected PC12 cells for the isolated compounds. Trewioidesine A exhibited a strong NF200 promoter activation, and application of trewioidesine A with low dose of NGF significantly induced the promoter activity over 50%.