Identification and screening of novel diterpenoids from roasted arabica coffee in the regulation of lipid content in white adipocytes.

Previous studies have shown that coffee has a role in regulating lipid metabolism. However, the active compounds and pharmacological mechanism(s) are still unclear. Here, four new coffee diterpenoids (1-4) were identified from roasted arabica coffee (Coffea arabica L.) beans, and together with 31 known coffee diterpenoids (5-35), their bioactivities in the regulation of lipid content in white adipocytes were evaluated. Based on their structures and correlated bioactivities, we proposed that the α,ß-unsaturated-γ-lactone moiety and hydroxyl group at C-3 are required for the bioactivity. Furthermore, the pharmacological approaches revealed that the active new diterpenoid, dehydrocaffarolide B, inhibited the Akt/mTOR/GSK3ß pathway and arrested cells in the G0/G1 phase of the mitotic clonal expansion process during the adipocyte differentiation and maturation, eventually resulting in the blunting of lipid accumulation in the adipocytes. Collectively, our findings identified four new diterpenoids of arabica coffee and elucidated a mechanism of an active lactone-type diterpenoid in the regulation of lipid content in white adipocytes.

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

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 two-dimensional 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.

Review on factors affecting coffee volatiles: from seed to cup.

The objective of this review is to evaluate the influence of six factors on coffee volatiles. At present, the poor aroma from robusta or low-quality arabica coffee can be significantly improved by advanced technology, and this subject will continue to be further studied. On the other hand, inoculating various starter cultures in green coffee beans has become a popular research direction for promoting coffee aroma and flavor. Several surveys have indicated that shade and altitude can affect the content of coffee aroma precursors and volatile organic compounds (VOCs), which remain to be fully elucidated. The emergence of the new roasting process has greatly enriched the aroma composition of coffee. Cold-brew coffee is one of the most popular trends in coffee extraction currently, and its influence on coffee aroma is worthy of in-depth and detailed study. Omics technology will be one of the most important means to analyze coffee aroma components and their quality formation mechanism. A better understanding of the effect of each parameter on VOCs would assist coffee researchers and producers in the optimal selection of post-harvest parameters that favor the continuous production of flavorful and top-class coffee beans and beverages. © 2021 Society of Chemical Industry.

Discovery of novel coffee diterpenoids with inhibitions on Cav3.1 low voltage-gated Ca2+ channel.

Seven new (1-4, 6-8) diterpenoids with rare skeletons and seven known ones (9, 12, 17, 18 and 23-25) were isolated from roasted beans of Coffea arabica L. Together with previously obtained diterpenoids, a total of 26 molecules (1-25, 4a) were evaluated their activities on Cav3.1 low voltage-gated Ca2+ channel. Compounds 1, 3, 6, 7, 12, 13, 17, 19 and 24 exhibited noticeable Cav3.1 inhibitions (41.2%-96.1%) at 10 µM. The IC50 values of 1, 6, 7, 12, 13, 17 and 24 are 2.9, 2.3, 0.68, 14.8, 11.6, 6.1 and 6.8 µM, respectively. The ring moiety at C-18 and C-19, and esterification of OH-17 with long-chain fatty acids seem important for their activities. Further studies indicated that 1 and cafestol may act on different binding sits with the Cav3.1 blocker Z944, which is in clinical trial. Significantly, the present study initially shows that coffee diterpenoids are potential natural resources for Cav3.1 inhibitors.

Chemical ingredients characterization basing on 1H NMR and SHS-GC/MS in twelve cultivars of Coffea arabica roasted beans.

This work aimed to study the composition differences of roasted beans between 12 coffee cultivars (Catimor 7963, HIBRIDO DE TIMOR, Ruiru 11, Castillo, DTARI 296, DTARI 366, DTARI 392, DTARI 585, SL28, SL34, Catuai-Amarelo and Catuai-Vermelho) from Bourbon-Typica group and Introgressed group under subtropical humid monsoon climate. The water-soluble compounds of roasted coffee beans were characterized by proton nuclear magnetic resonance spectroscopy (1H NMR), and the aroma components were analyzed by static headspace gas chromatography mass spectrometry (SHS-GC/MS). In total, 20 water soluble compounds and 43 volatile compounds were identified. Both water-soluble and volatile compounds are rich in acidic substances, and the content varied depending on the cultivars. Furthermore, principal component analysis (PCA) clustered 12 coffee cultivars into four groups. The four different chemically defined clusters of Arabica cultivars produced by chemical differences cannot reflect the traditional grouping based on introgressed, and it is one-sided to judge coffee quality based on lineage. These results give further insight into the quality characteristics of different coffee cultivars, which is of great significance for guiding the adjustment of cultivars' structure and the breeding of new cultivars.

Morphological Changes and Component Characterization of Coffee Silverskin.

Nuclear magnetic resonance (NMR) spectroscopy was used for the qualitative and quantitative analysis of aqueous extracts of unroasted and roasted coffee silverskin (CS). Twenty compounds were identified from 1D and 2D NMR spectra, including caffeine, chlorogenic acid (CGA), trigonelline, fructose, glucose, sucrose, etc. For the first time, the presence of trigonelline was detected in CS. Results of the quantitative analysis showed that the total amount of the main components after roasting was reduced by 45.6% compared with values before roasting. Sugars in the water extracts were the main components in CS, and fructose was the most abundant sugar, its relative content accounting for 38.7% and 38.4% in unroasted and roasted CS, respectively. Moreover, 1D NMR combined with 2D NMR technology shows application prospects in the rapid, non-destructive detection of CS. In addition, it was observed by optical microscopy and scanning electron microscopy (SEM) that the morphology of CS changed obviously before and after roasting.

New ent-kaurane diterpenes from the roasted arabica coffee beans and molecular docking to α-glucosidase.

Ten new (1-10) and five known (11-15) ent-kaurane diterpene derivatives were identified from the roasted beans of coffea arabica. Their structures were established by extensive spectroscopic analysis including 1D, 2D NMR (HSQC, HMBC, COSY, and ROESY), HRESIMS, and X-ray diffraction analysis. Compounds 1-3 were three types of rearranged ent-kaurane diterpenes, and compounds 4 and 5 were diterpene esters with a rare 6-hydroxyhexanoyl at C-17. Compounds 6, 8, 14, and 15 showed moderate inhibitory effect on α-glucosidase with IC50 values of 149.92 ± 2.52, 23.23 ± 1.03, 54.58 ± 4.21, 54.16 ± 3.95 µM, respectively, compared to the positive control (60.71 ± 16.45 µM). The results of activity assay showed that diterpenes with the double bond between C-15 and C-16 exhibited stronger α-glucosidase inhibitory activity. Further molecular docking experiments were adopted to discuss the mechanism of activity.