Seven new chemical constituents from the underground parts of Eupatorium chinense

Chemical Constituents and Their Bioactivities of Plants from the Genus Eupatorium (2015-Present)

The genus Eupatorium belongs to the Asteraceae (Compositae) family and has multiple properties, such as invasiveness and toxicity, and is used in folk medicine. The last review on the chemical constituents of this genus and their biological activities was published in 2015. The present review provides an overview of 192 natural products discovered from 2015 to the present. These products include 63 sesquiterpenoids, 53 benzofuran derivatives, 39 thymol derivatives, 15 fatty acids, 7 diterpenoids, 5 monoterpenoids, 4 acetophenones, and 6 other compounds. We also characterized their respective chemical structures and cytotoxic, antifungal, insecticidal, antibacterial, anti-inflammatory, and antinociceptive activities.

Synthesis and inhibitory activity of euparin derivatives as potential dual inhibitors against α-glucosidase and protein tyrosine phosphatase 1B (PTP1B)

Diabetes mellitus is a serious threat to human life and health. The α-glucosidase and protein tyrosine phosphatase 1B (PTP1B) were important targets for the treatment of type 2 diabetes mellitus. In this paper, euparin, a natural product from Eupatorium chinense possessed extensive pharmacological activities, was selected as the lead compound. It was derived into chalcone compounds with high efficiency, and the inhibitory activities of these 30 products on α-glucosidase and PTP1B were tested. The results showed that compounds 12 and 15 had good inhibitory activities against both enzymes. The IC50 value of 12 to inhibit α-glucosidase and PTP1B was 39.77 and 39.31 μM, and the IC50 value of 15 to inhibit α-glucosidase and PTP1B was 9.02 and 3.47 μM, respectively. In addition, molecular docking results showed that compounds 12 and 15 exhibited good binding affinities toward both α -glucosidase and PTP1B with negative binding energies. The results of the present study demonstrate that compounds 12 and 15 might be beneficial in the treatment of type 2 diabetes.

New Benzofuran Oligomers from the Roots of Eupatorium heterophyllum Collected in China

The chemical constituents of two root samples of Eupatorium heterophyllum DC. collected in Yunnan Province, China, were investigated. Five new oligomeric benzofurans (1-5), nine new benzofuran/dihydrobenzofuran derivatives, and a new thymol analog were isolated, and their structures were determined using extensive spectroscopic techniques, such as 1D and 2D NMR spectroscopy and DFT calculations of the CD spectra. Most of the new compounds, including oligomeric benzofurans (1-5), were obtained from only one of the root samples. Furthermore, this is the first example that produces oligomeric benzofurans in this plant. These results imply that diversification of secondary metabolites in E. heterophyllum is ongoing. Plausible biosynthetic pathways for 1-5 are also proposed.

Ten undescribed cadinane-type sesquiterpenoids from Eupatorium chinense

Ten undescribed cadinane-type sesquiterpenes (1-10) were isolated from the whole plant of Eupatorium chinense. Their planar structures were mainly elucidated by extensive analysis of spectroscopic data and DFT NMR calculations. The absolute configurations of 1, 2, and 3 were determined by TDDFT ECD calculations while those of compounds 4-7 and 9 were confirmed by single crystal X-ray diffraction experiments. Compounds 2 and 3 are a pair of C-10 epimers, compounds 4 and 5 a pair of C-1 epimers, and compounds 9 and 10 a pair of compounds isomerized at both C-1 and C-10. A possible biosynthetic pathway for these new sesquiterpenes was proposed.

Alkyl-benzofuran dimers from Eupatorium chinense with insulin-sensitizing and anti-inflammatory activities

Five new racemic alkyl-benzofuran dimers, (±)-dieupachinins I-M (1-5), were isolated from the root tubers of Eupatorium chinense, a well-known traditional Chinese medicine for the treatment of diphtheria in Guangdong province. The structures of these compounds, especially the first examples of 12,10'-epoxy dimer dieupachinin I (1), 12-nor-dimer dieupachinin J (2), and 12,12'-dinor-dimer dieupachinin K (3), were elucidated by spectroscopic data analysis. Chiral resolution were further carried out on a cellulose column by HPLC, and compounds 2-5 were successfully separated into two enantiomers, respectively. The absolute configurations of (+)-(2-5) and (-)-(2-5) were established by theoretical ECD calculation. All the compounds were evaluated for insulin-stimulated glucose uptake in C2C12 myotubes and (±)-dieupachinin I (1) exhibited the best activity. Compound 1 enhanced insulin-stimulated glucose uptake via activating the insulin receptor substrate 1/protein kinase B/glycogen synthase kinase-3β signaling pathway. Moreover, all the isolates were tested for their nitric oxygen (NO) inhibitory effects in lipopolysaccharide-treated RAW264.7 macrophages, and compounds (±)-1, (±)-2, and (±)-4 showed promising inhibitory effects with IC₅₀ values of 6.42 ± 1.85, 6.29 ± 1.94, and 16.03 ± 2.07 μM, respectively. (±)-Dieupachinin I (1) again dose-dependently suppressed LPS-induced expression of inducible NO synthase and nuclear translocation of p65.