Mei-Hua Yu

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.

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.

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.

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.

New Isoprenylated Phenolic Compounds from Morus laevigata.

Two new isoprenylated flavonoids, laevigasins A and B (1 and 2, resp.), and one new isoprenylated 2‐arylbenzofuran, leavigasin C (3), together with eight known compounds, 4–11, were isolated from the twigs of Morus laevigata. Their structures were elucidated by spectroscopic methods. Laevigasin A (1) showed significant inhibitory effect on α‐glucosidase in vitro. Notabilisin E (5), taxifolin (10), and hultenin (11) inhibited PTP1B phosphatase activity in vitro.

Triterpenoids and α-glucosidase inhibitory constituents from Salacia hainanensis

Thirteen triterpenoids (1-13), including two new lupane triterpenoids, salacinins A and B (1 and 2), as well as one new friedelane triterpenoid, salacinin C (3), were isolated from the roots and stems of Salacia hainanensis. The structures of new compounds were elucidated by extensive spectroscopic analysis including 1D and 2D NMR, and MS experiments. Compound 1 possesses rare 2,3-seco-lupane skeleton. Compounds 4, 6 and 7 showed inhibitory effects on α-glucosidase in vitro.

Five Pairs of Meroterpenoid Enantiomers from Rhododendron capitatum

Chemical investigation on the aerial parts of Rhododendron capitatum resulted in the discovery of five enantiomeric pairs of new meroterpenoids, (+)-/(-)-rhodonoids C (1a and 1b), E (3a and 3b), F (4a and 4b), and (-)-/(+)-rhodonoids D (2a and 2b) and G (5a and 5b). These enantiomeric pairs existed as partial racemates in a plant and were obtained by chiral HPLC separation. Their structures with absolute configurations were assigned by spectroscopic data, single-crystal X-ray diffraction, and ECD analysis. Compounds 1a and 1b are the first pair of meromonoterpenes incorporating an unprecedented 6/6/6/5 ring system, and 1a showed antiviral activity against herpes simplex virus type 1 (HSV-1) in vitro. Compounds 2a and 2b are the first examples of meromonoterpenes featuring a unique 6/6/5/5 ring system.

Isoprenylated phenolic compounds with tyrosinase inhibition from Morus nigra

Abstract A new isoprenylated sanggenon-type flavanone, nigrasin K (1), together with three known analogs (2–4) and five known Diels–Alder adducts (5–9), were isolated from the twigs of Morus nigra. Their structures were elucidated by spectroscopic methods. Sanggenon M (2), chalcomoracin (5), sorocein H (6), kuwanon J (7), sanggenon C (8), and sanggenon O (9) showed significant inhibitory effects on mushroom tyrosinase.

Isoprenylated flavonoids from Morus nigra and their PPAR γ agonistic activities

A novel dihydroflavonol unprecedentedly with a prenyl group at C-2, nigragenon A (1), four new sanggenon-type flavonones, nigragenons B-E (2-5), along with six known isoprenylated flavonoids (6-11) were isolated from the twigs of Morus nigra. Their structures were elucidated through extensive analysis of spectroscopic data. Interestingly, compound 1 was the first reported biogenetic precursor of sanggenon-type flavanones and the biogenetic pathway from 1 to sanggenol F was proposed. The PPAR γ agonistic activity was investigated in HEK293 cells using dual luciferase reporter assay. Compounds 2, 4, 7, and 9 showed obvious agonistic activities on PPAR γ, and compound 2 was a potential PPAR γ partial agonist. Moreover, the preliminary structure-activity relationships for the tested compounds were discussed.

Phenolic compounds isolated from Morus nigra and their α-glucosidase inhibitory activities

Abstract A novel benzofuranone unprecedentedly with a prenyl group at C-3, nigranol A (1), a new flavonol, nigranol B (2), and three known compounds, sanggenon M (3), nigrasin C (4), and nigrasin A (5) were isolated from the twigs of Morus nigra Linn. Their structures were elucidated on the basis of the analysis of multiple spectroscopic data. All of the compounds, along with eight previously isolated ones (6–13) were investigated for their α-glucosidase inhibitory activities. The result showed that compounds 1–13 except 4 exhibited prominent inhibitory activities against α-glucosidase. Among them, compounds 2 and 7 were the best α-glucosidase inhibitory candidates with IC50 values at 1.63 and 1.43 μM, respectively. Furthermore, the structure-activity relationships of the sanggenon-type flavanones were summarized.