Ai-Jun Hou

2-Arylbenzofuran, Flavonoid, and Tyrosinase Inhibitory Constituents of Morus yunnanensis

Two novel 2-arylbenzofuran dimers, morusyunnansins A and B (1 and 2), two new biflavonoids, morusyunnansins C and D (3 and 4), two new flavans, morusyunnansins E and F (5 and 6), and four known flavans (7-10) were isolated from the leaves of Morus yunnanensis. Compounds 5-8 showed potent inhibitory effects on mushroom tyrosinase with IC(50) values ranging from 0.12 ± 0.02 to 1.43 ± 0.43 μM.

Isoprenylated Flavonoids and Adipogenesis-Promoting Constituents from Morus nigra

Ten new isoprenylated flavonoids, nigrasins A-J (1-10), and three known compounds were isolated from the twigs of Morus nigra. Compounds 8 and 9 promoted adipogenesis, characterized by increased lipid droplet and triglyceride content in 3T3L1 cells, and induced up-regulation of the expression of adipocyte-specific genes, aP2 and GLUT4.

Isoprenylated Flavonoid and Adipogenesis-Promoting Constituents of Dodonaea viscosa

Ten new isoprenylated flavonol derivatives, dodoviscins A-J (1-10), and seven known compounds (11-17) were isolated from the aerial parts of Dodonaea viscosa. Compounds 1, 2, 4, 5, 7-9, 5,7,4-trihydroxy-3,5-bis(3-methyl-2-buten-1-yl)-3-methoxyflavone (11), 5,7,4-trihydroxy-3,5-bis(3-methyl-2-buten-1-yl)-3,6-dimethoxyflavone (12), 5,7,4-trihydroxy-3-(4-hydroxy-3-methylbutyl)-5-(3-methyl-2-buten-1-yl)-3,6-dimethyoxyflavone (13), sakuranetin (14), and blumeatin (15) promoted adipocyte differentiation as characterized by increased triglyceride levels in 3T3L1 cells. Compounds 1, 13, and 15 also enhanced the accumulation of lipid droplets and induced upregulation of the expression of the adipocyte-specific genes aP2 and GLUT4.

Diels–Alder adducts with PTP1B inhibition from Morus notabilis

Eight Diels-Alder adducts, morbilisins A-H (1-8), a known analogue, chalcomoracin (9), together with eleven known flavonoids and 2-arylbenzofurans, were isolated from the leaves of Morus notabilis. Their structures were elucidated by extensive spectroscopic analysis, including 1D, 2D NMR, MS, and ECD data. Compounds 1, 5, and 7-9 showed inhibition against PTP1B phosphatase activity in vitro.

Two Enantiomeric Pairs of Meroterpenoids from Rhododendron capitatum.

Two enantiomeric pairs of meroterpenoids, (-)- and (+)-rhodonoids A (1a and 1b) and B (2a and 2b), were isolated unprecedentedly from partially racemic mixtures that naturally occurred in Rhododendron capitatum. Their structures were fully determined by spectroscopic data, X-ray crystallography, and electronic circular dichroism analysis. Compounds 1a and 1b are the first examples of meromonoterpenes featuring a unique 6/6/6/4 ring system. Compounds 2a and 2b showed PTP1B inhibitory activity.

New Isoprenylated 2-Arylbenzofurans and Pancreatic Lipase Inhibitory Constituents from Artocarpus nitidus

Two new isoprenylated 2‐arylbenzofurans, artonitidin A (=(2′R)‐2′,3′‐dihydro‐2′‐(1‐hydroxy‐1‐methylethyl)‐5′,7‐bis(3‐methylbut‐2‐en‐1‐yl)‐2,4′‐bi‐1‐benzofuran‐6,6′‐diol; 1) and artonitidin B (=5‐[6‐hydroxy‐7‐(3‐methylbut‐2‐en‐1‐yl)‐1‐benzofuran‐2‐yl]‐4‐(3‐methylbut‐2‐en‐1‐yl)benzene‐1,3‐diol; 2), together with 14 known compounds, 3–16, were isolated from the stems of Artocarpus nitidus Trec. The structures were elucidated by spectroscopic methods. Norartocarpin (3), cudraflavone C (5), brosimone I (8), artotonkin (11), albanin A (13), and artopetelin M (14) showed inhibitory effects on pancreatic lipase with IC50 values ranging from 1.8±0.1 to 63.8±3.6u2005μM.

New isoprenylated flavones and stilbene derivative from Artocarpus hypargyreus.

Three new isoprenylated flavones, hypargyflavones A–C (1–3, resp.), and one novel stilbene derivative, hypargystilbene A (4), together with seven known compounds, 5–11, were isolated from the stems of Artocarpus hypargyreus Hance. The structures were elucidated by spectroscopic methods. Hypargyflavone A (1), cudraflavone C (8), brosimone I (10), and norartocarpin (11) showed inhibitory effects on pancreatic lipase.

New isoprenylated flavonoids and adipogenesis-promoting constituents from Morus notabilis

Five new isoprenylated flavonoids, notabilisins A-E (1-5), and two known Diels-Alder adducts (6 and 7), were isolated from the twigs of Morus notabilis. Compounds 4 and 5 possess two novel pyran rings, which may be biogenetically derived from 3. Compounds 1 and 3 significantly promoted adipogenesis, characterized by increased lipid droplet and triglyceride content in 3T3L1 cells, and induced up-regulation of the expression of adipocyte-specific genes, aP2 and GLUT4.

(2S)-7,4′-dihydroxy-8-prenylflavan stimulates adipogenesis and glucose uptake through p38MAPK pathway in 3T3-L1 cells

Adipose tissue plays a key role in the development of obesity and diabetes. Natural products are one of the main sources for discovering new lead compounds. In the present study, (2S)-7,4-dihydroxy-8-prenylflavan (DHPF), a natural prenylated flavan isolated from Morus yunnanensis, was found to significantly promote adipogenesis and increase glucose uptake in 3T3-L1 cells. Real-time PCR results showed that DHPF increased the expression of glucose and lipid metabolism-related genes (C/EBPα, PPARγ, aP2, GLUT4 and adiponectin) and decreased the expression of inflammatory cytokine TNF-α. Western blotting further revealed that DHPF activated p38 MAPK at the initial stage of 3T3-L1 preadipocyte differentiation. DHPF-induced activation of p38, adipogenesis and glucose uptake were effectively blocked by SB203580, a specific p38 inhibitor. These results indicate that DHPF could stimulate adipogenesis and increase glucose uptake through the p38 MAPK pathway, and DHPF may be useful for the prevention and treatment of obesity-associated disorders such as type 2 diabetes (T2D).

2-Arylbenzofuran and tyrosinase inhibitory constituents of Morus notabilis

Phytochemical investigation of the stem of Morus notabilis led to the isolation and characterization of 10 compounds of 2-arylbenzofurans (1–10), including two new compounds, (2′R)-2′,3′-dihydro-2′-(1-hydroxy-1-methylethyl)-2,6′-bibenzofuran-6,4′-diol (1) and 5,6-dimethoxy-2-(3-hydroxy-5-methoxyphenyl)benzofuran (2). Moracins O (6) and P (10) showed inhibitory effects on mushroom tyrosinase with IC50 values being lower than that of kojic acid.