Phenolic Compounds from the Leaves of Castanopsis fargesii

Triterpene hexahydroxydiphenoyl ester and phenol glucosides from the leaves of Castanopsis eyrie (Champ. ex Benth.) Hutch

As a part of our systematic study on Castanopsis genus (Fagaceae), one new triterpene hydrolysable tannin (1) and two new phenol glucosides (2 and 3) were isolated from the leaves of Castanopsis eyrei (Champ. ex Benth.) Hutch. Compound 1 was identified as a triterpene hexahydroxydiphenoyl (HHDP) ester. This type of compounds has only been isolated from Castanopsis genus. The structures of 1-3 were elucidated by the combination of spectroscopic analysis (MS, 1 D and 2 D NMR) and chemical evidence.

Phenolic and flavonoid compounds from the fruit shell of Camellia oleifera

A new phenolic compound oleiphenol (1), and a new dihydrochalcone oleifechalcone (2) along with seven known compounds (3-9) were isolated from the fruit shell of Camellia oleifera Abel. The planar structures of compounds 1 and 2 were determined on the basis of extensive spectroscopic analyses (IR, UV, NMR, and HR-ESI-MS) and comparison with literature data. The absolute configurations of the new structures were determined by ECD calculations and chemical methods. In addition, compounds 1-9 underwent a series of pharmacological activity tests, including cytotoxic, anti-inflammatory, anti-RSV and antioxidant activities.

Two truxinate derivatives and a phenyldilactone from the leaves of Castanopsis eyrei

Phytochemical investigation of the Leaves of Castanopsis eyrei led to the isolation of two new natural truxinate derivatives and a new phenyldilactone. The structures of the new natural compounds were determined by spectroscopic methods and chemical evidence as 3,3',4,4'-tetrahydroxy-β-truxillic acid (1), 3,3',4,4'-tetrahydroxy-δ-truxillic acid (2), 3'-hydroxymaysedilactone A (3). Establishment of a Caenorhabditis elegans lipid metabolism model using GFP and mCherry fluorescently labeled lipid droplets to screen compound 3 for its activity in reducing lipid accumulation.

Isolation of Two New Phenolic Glycosides from Castanopsis chinensis Hance by Combined Multistep CC and HSCCC Separation and Evaluation of Their Antioxidant Activity

The characteristics of high polarity and susceptibility to oxidation in phenolic glycosides increase the difficulty of their separation from natural products. In the present study, two new phenolic glycosides with similar structures were isolated from Castanopsis chinensis Hance using a combination of multistep CC and high-speed countercurrent chromatography. Preliminary separation of the target fractions was carried out by Sephadex LH-20 chromatography (100-0% EtOH in H₂O). High-speed countercurrent chromatography with an optimized solvent system of N-Hexane/Ethyl acetate/Methanol/Water (1:6:3:4, v/v/v/v) with a satisfactory stationary phase retention and separation factor was used for further separation and purification of the phenolic glycosides. Consequently, two new phenolic glycoside compounds were obtained with purities of 93.0% and 95.7%. 1D-NMR and 2D-NMR spectroscopy, mass spectrometry, and optical rotation were employed to identify their structures, which were assigned as chinensin D and chinensin E. The antioxidant and α-glucosidase inhibitory activities of these two compounds were evaluated using a DPPH antioxidant assay and a α-glucosidase inhibitory assay. Both compounds showed good antioxidant activity with IC₅₀ values of 54.5 ± 0.82 µg/mL and 52.5 ± 0.47 µg/mL. The α-glucosidase inhibitory activity of the compounds was poor. The successful isolation and structure identification of the two new compounds provides materials not only for a systematic isolation method of phenolic glycosides with similar structures, but also for the screening of antioxidants and enzyme inhibitors.

Three new compounds from the leaves of Castanopsis tibetana Hance

Three new compounds (6S,9S)-6'-galloyl-roseoside (1), purpurogallin ethyl carboxylate (2), and tibetana A (3) were isolated from 80% methanol extract of the leaves of Castanopsis tibetana Hance. Their structures were elucidated based on comprehensive spectroscopic methods and chemical data, including optical rotation, UV, MS, 1 D and 2 D NMR spectra. Compounds 1 and 3 were evaluated for their α-glucosidase inhibitory activity, pancreatic lipase inhibitory activity, and tyrosinase inhibitory activity.