Unusual ent-Kaurane Diterpenes from the Coffea Cultivar S288 Coffee Beans and Molecular Docking to α-Glucosidase

Abstract

A total of 11 new (1−11) and 2 known (12 and 13) ent-kaurane diterpene derivatives were identified from the roasted beans of Coffea cultivar S288. Their structures were established by extensive spectroscopic analysis, including one-and twodimensional nuclear magnetic resonance (heteronuclear single-quantum correlation, heteronuclear multiple-bond correlation, correlation spectroscopy, and rotating-frame Overhauser enhancement spectroscopy), high-resolution electrospray ionization mass spectrometry, and X-ray analyses. Cafespirone acid A (1) represents the first example of diterpene featuring a spirocyclic skeleton constructed from a 6/6/5 tricyclic system. Cafeane acid A (2) possesses a 6/6/6/5 tetracyclic system as a result of the C/D ring rearrangement. Furthermore, compounds 1−12 were evaluated for their α-glucosidase inhibitory activity. The results showed that compounds 2, 4, 5, 6, 7, 10, and 11 had a moderate inhibitory effect on α-glucosidase, and half-maximal inhibitory concentration values of compounds 4, 6, 7, and 10 were 18.76 ± 1.46, 4.88 ± 0.03, 12.35 ± 0.91, and 12.64 ± 0.59 μM, respectively, compared to the positive control acarbose (60.71 ± 16.45 μM). Additionally, the molecular docking experiments showed that the carbonyl group at C-19 of compounds 4, 6, and 7 formed strong hydrogen bonds with ARG315, which may make them have moderate inhibitory activity.

Utilization of the By-Product of Corn: Guided Identification of Bioactive Terpenoids from Stigma Maydis (Corn Silk)

“…Comprehensive interpretation of 13 C (Table ) and HSQC spectra indicated attendance for 24 carbon resonances comprising a formyl carbon, a carbonyl carbon, five methine carbons, 11 methylene carbons, three methyl carbons, and three sp 3 quaternary carbons. On account of aforementioned spectroscopic evidence, 1 was suggested to be an ent -kaurane-type diterpenoid comprising 6/6/6/5-fused rings A, B, C, and D, which was further authenticated by means of HMBC cross peaks. − Substitution of hydroxy at C-2 was deduced via HMBC correlations (Figure S5) of H-1 with C-20 and H-3 with C-1/C-5. The correlations of 19-CHO with C-3 affirmed the C-4 location of the formyl group.…”

Exploring Active Ingredients, Beneficial Effects, and Potential Mechanism of Allium tenuissimum L. Flower for Treating T2DM Mice Based on Network Pharmacology and Gut Microbiota

“…The α−glucosidase inhibitory activity assay method of A. tenuissimum flower flavonoids was slightly modified based on previous studies [ 22 , 23 , 24 ]. A 96−well plate was used for preparing the mixture consisting of 0.1 M PBS (pH 6.8), 1.0 mg/mL sample solution, and 2 U/mL α−glucosidase, which were incubated at 37 °C for 10 min.…”

Application of Molecular Simulation Methods in Food Science: Status and Prospects

“…In addition, hydrophobic forces also play a vital role in the binding process, consistent with the thermodynamic experiment. Hong et al 22 explored the structure−activity relationship of ent-kaurane diterpene derivatives and α-glucosidase based on molecular docking (AutoDock). They discovered that the binding modes of diterpenes (2 and 5) were quite similar to acarbose, indicating they may have an identical inhibitory mechanism.…”