Identification of Small-Molecule Bioactive Constituents from the Leaves of Vaccinium bracteatum Confirms It as a Potential Functional Food with Health Benefits

Bioactive neolignan, iridoid and flavonoid glycosides from the leaves of Vaccinium bracteatum

Two neolignan glycosides including a new one (1), along with seven iridoid glycosides (3 - 9) and nine flavonoid glycosides (10 - 18), were isolated from the leaves of Vaccinium bracteatum. Their structures were established mainly on the basis of 1D/2D NMR and ESIMS analyses, as well as comparison to known compounds in the literature. The structure of 1 with absolute stereochemistry was also confirmed by chemical degradation and ECD calculation. Selective compounds showed antiradical activity against ABTS and/or DPPH. Moreover, several isolates also suppressed the production of ROS in RAW264.7 cells and exerted neuroprotective effect toward PC12 cells.

Sesquiterpenoids and steroids from Eupatorium fortunei and their inhibitory effects on NO production

Two heterodimers including a clovane-phenylpropanoid hybrid (1) and a clovane-menthane hybrid (2), five linear sesquiterpenoids incorporating a tetrahydrofuran ring (3-6 & 8), and four steroids (7 & 9-11), were separated from the ethanolic extract of a well-known aromatic and medicinal herb Eupatorium fortunei. Their structures were characterised by detailed analyses of spectroscopic data and comparison with known analogues, with seven (1-7) of them being described for the first time. The hybrids 1 and 2 represent the first examples of clovane type sesquiterpenoids hybridising with other class of natural products, and compounds 3-6 and 8 are first linear sesquiterpenyl constituents reported from the title species. All the isolates were evaluated for their inhibitory effect on the NO production induced by LPS in murine RAW264.7 macrophage cells, and 1, 7, 10 and 11 exhibited moderate activity with IC50 values in the range of 24.4-43.5 µM.

Anti-inflammatory Polyketides from an Endophytic Fungus Chaetomium sp. UJN-EF006 of Vaccinium bracteatum

Seven new polyketides including three chromone derivatives (1-3) and four linear ones incorporating a tetrahydrofuran ring (4-7), along with three known compounds (8-10), were obtained from the fermentation of an endophytic fungus (Chaetomium sp. UJN-EF006) isolated from the leaves of Vaccinium bracteatum. The structures of these fungal metabolites have been elucidated by spectroscopic means including MS, NMR and electronic circular dichroism. A preliminary anti-inflammatory screening with the lipopolysaccharide (LPS) induced RAW264.7 cell model revealed moderate NO production inhibitory activity for compounds 1 and 4. In addition, the expression of three LPS-induced inflammatory factors IL-6, iNOS and COX-2 was also blocked by 1 and 4.

Bioactive monoterpenoids and acetophenones from the aerial parts of Eupatorium fortunei

Thirty-nine thymol and acetophenone derivatives, including eight pairs of enantiomers, were isolated from the aerial parts of Eupatorium fortunei. Their structures were assigned by detailed analyses of spectroscopic data and NMR calculations based on density functional theory, with 18 ones (1a/1b-14) being previously undescribed compounds. While the absolute configurations of 1a/1b, 2a/2b, 4, 6a/6b, 7, 11a/11b and 15a/15b-18a/18b were established by calculations of electronic circular dichroism data, that of 14 was determined by modified Mosher's method. Compounds 1a/1b and 2a/2b represent a previously unreported type of monoterpenoid dimers via an amide linkage, and compound 3 is a monoterpene-phenylpropanoid hybrid connected through an ester bond. Among the known molecules, the formerly mis-assigned structures of 15a/15b and 22 were revised, and pure natural enantiomers of 16a/16b-18a/18b were reported for the first time. Selective compounds showed antiradical and NO production inhibitory activities in the preliminary biological screening. Compound 31 was further demonstrated to alleviate oxidative stress by activating Nrf2 signaling pathway.