Bi-2-(2-phenethyl)chromone derivatives from agarwood of Aquilaria filaria in the Philippines.

Twelve undescribed 2-(2-phenethyl)chromone dimers (1-12) were isolated from EtOAc extract of agarwood originating from Aquilaria filaria in the Philippines, guided by a UHPLC-MS analysis. Their structures were elucidated by 1D NMR, 2D NMR, and HR-ESI-MS spectra. The absolute configuration of 2-(2-phenylethyl)chromone dimers was determined by single-crystal X-ray diffraction analysis and comparison of the experimental and calculated ECD spectra. Compounds 1, 2, 5 and 9-12 exhibited potent to moderate anti-inflammatory activity with IC50 values in the range of 22.43 ± 0.86 to 53.88 ± 4.06 µM.

Six unprecedented 2-(2-phenethyl)chromone dimers from agarwood of Aquilaria filaria.

Six new dimeric 2-(2-phenylethyl)chromones (1-6) were successfully isolated from the ethanol extract of agarwood of Aquilaria filaria from Philippines under HPLC-MS guidance. Compounds 1-6 are all dimers formed by linking 5,6,7,8-tetrahydro-2-(2-phenylethyl)chromone and flindersia 2-(2-phenylethyl)chromone via a single ether bond, and the linkage site (C5-O-C8'') of compound 2 is extremely rare. A variety of spectroscopic methods were used to ascertain their structures, including extensive 1D and 2D NMR spectroscopic analysis, HRESIMS, and comparison with literature. The in vitro tyrosinase inhibitory and anti-inflammatory activities of each isolate were assessed. Among these compounds, compound 2 had a tyrosinase inhibition effect with an IC50 value of 27.71 ± 2.60 µM, and compound 4 exhibited moderate inhibition of nitric oxide production in lipopolysaccharide-stimulated RAW264.7 cells with an IC50 value of 35.40 ± 1.04 µM.

Identification of volatile compounds and their bioactivities from unpolar fraction of Alpinia oxyphylla Miq. and mining key genes of nootkatone biosynthesis.

In this study, analysis of the chemical constituents and bioactivities of the unpolar fractions [petroleum ether (PE) and chloroform (C)] of fruits and leaves of Alpinia oxyphylla Miq. were carried out, as well as the bioactivities of the main compounds nootkatone and valencene. From PE and C fractions of the fruits, and PE fraction of the leaves, 95.80%, 59.30%, and 82.11% of the chemical constituents respectively were identified by GC-MS. Among these identified compounds, nootkatone was the main compound in all of three fractions, while valencene was the second main compound in the PE fractions of the fruits and leaves. The bioactivities results showed that all of the fractions and the major compound nootkatone showed tyrosinase inhibitory, as well as inhibitory effect on NO production in LPS-stimulated RAW264.7 cells. While valencene only presented inhibitory activity on NO production in RAW264.7 cells. The critical genes involved in nootkatone biosynthesis in A. oxyphylla were identified from the public transcriptome datasets, and protein sequences were preliminarily analyzed. Our studies develop the usage of the unpolar fractions of A. oxyphylla, especially its leaves as the waste during its production, and meanwhile provide the gene resources for nootkatone biosynthesis.

Sesquiterpenoids and bibenzyl derivative from Dendrobium hercoglossum.

Three new sesquiterpenoids, dendrohercoglin A - C (1-3), and one new bibenzyl derivative, dendronbiline D (4), together with nine known sesquiterpenoids (5-13) were isolated from Dendrobium hercoglossum. The structures of the new compounds were elucidated by extensive spectroscopic analysis as well as NMR and ECD calculations. All the compounds were evaluated for their neuroprotective and anti-inflammatory activities. Compounds 2 and 3 increased the H2O2-damaged SH-SY5Y cell viabilities from 43.3% to 58.6% and 68.4%, respectively. Compound 4 exhibited pronounced anti-inflammatory activity with IC50 value of 9.5 ± 0.45 µM which was superior to the reference compound quercetin (IC50: 15.7 ± 0.89 µM).

Two new anti-inflammatory trachylobane diterpenoids from Euphorbia atoto.

Two new rare trachylobane euphoratones A-B (1-2), together with five known diterpenoids (compounds 3-7), were isolated from the aerial parts of Euphorbia atoto. Their structures were unambiguously elucidated through HRESIMS, 1D and 2D NMR spectral analysis. Compounds 1, 3, 4 and 7 showed weak anti-inflammatory activities (IC50 77.49 ± 6.34, 41.61 ± 14.49, 16.00 ± 1.71 and 33.41 ± 4.52 µM, respectively), compared to the positive control quercetin (IC50 15.23 ± 0.65 µM).

Evaluating the Antioxidant Properties of the Leaves and Stems of Alpinia oxyphylla In Vitro and Its Growth-Promoting, Muscle Composition Change, and Antioxidative Stress Function on Juvenile Litopenaeus vannamei.

Alpinia oxyphylla is a homology of medicine and food. This study aims to investigate the dominant chemical composition and explore the antioxidant properties of the ethanol extract of the leaves and stems of A. oxyphylla (AOE) on juvenile shrimp, Litopenaeus vannamei. An in vitro test showed that AOE and its dominant chemical composition procyanidin B-2 (1) and epicatechin (2) presented DPPH and ABTS radical scavenging activities. A shrimp feeding supplement experiment revealed that shrimp growth parameters and muscle composition were improved significantly when fed with a 200 mg/Kg AOE additive. Meanwhile, the activities of antioxidant enzymes (CAT, GSH-Px, SOD, and T-AOC) in serum and the liver and the expression of related genes (LvMn-SOD, LvCAT, LvproPo, and LvGSH-Px) were enhanced with various degrees in different AOE additive groups while the content of MDA was significantly decreased. Moreover, the antioxidative effect of AOE additive groups on shrimp was also observed in an acute ammonia nitrogen stress test.

Anti-inflammatory and α-glucosidase inhibitory constituents from Dendrobium nobile Lindl.

Four new compounds ((±)-1-3), including one pair of enantiomers ((±)-1), along with 11 known bibenzyls (4-14) were isolated from Dendrobium nobile. The structures of the new compounds were elucidated by spectroscopic methods including 1D and 2D NMR as well as HRESIMS. The configurations of (±)-1 were established via the electronic circular dichroism (ECD) calculations. Compounds (+)-1 and 13 displayed pronounced α-glucosidase inhibitory activities with IC50 values of 16.7 ± 2.3 and 13.4 ± 0.2 µM, respectively, which were comparable to that of genistein (IC50, 8.54 ± 0.69 µM). Kinetic studies revealed that (+)-1 and 13 were non-competitive inhibitors against α-glucosidase and molecular docking simulations illuminated their interactions with α-glucosidase. All the isolates were also evaluated for their anti-inflammatory activities. Compounds 4, 5, and 11 exhibited superior inhibition activity with IC50 values ranging from 9.2 to 13.8 µM to that of quercetin (IC50, 16.3 ± 1.1 µM).

Cytotoxic steroids from the stems of Strophanthus divaricatus.

Phytochemical investigation on the stems of Strophanthus divaricatus led to the isolation of four undescribed cardiac glycosides and one undescribed C21 pregnane, together with eleven known steroids. Their structures were elucidated by a comprehensive analysis of HRESIMS, 1D and 2D NMR spectra. The absolute configuration of 16 was determined by comparison of the experimental and computed ECD spectra. Compounds 1-13 and 15 displayed potent to significant cytotoxicity against human cancer cell lines K562, SGC-7901, A549 and HeLa with IC50 values of 0.02-16.08, 0.04-23.13, 0.06-22.31 and 0.06-15.13 µM, respectively.

Dimeric 2-(2-phenethyl)chromones from agarwood of Aquilaria filaria.

Four new 2-(2-phenethyl)chromone dimers (1-4) were isolated from EtOAc extract of agarwood originating from Aquilaria filaria from Philippines. Their structures were elucidated by spectroscopic analysis (1D and 2D NMR, and HRESIMS) and comparison of the experimental and computed ECD curves. Compounds 1-4 exhibited inhibition of nitric oxide production in lipopolysaccharide-stimulated RAW264.7 cells with IC50 values in the range from 33.94 to 57.53 µM.

Triterpenoids as bivalent and dual inhibitors of acetylcholinesterase/butyrylcholinesterase from the fruiting bodies of Inonotus obliquus.

Inonotus obliquus, an edible and medicinal mushroom parasitic on birches, has been used in human diet and for traditional therapies in the high latitude regions of Europe and Asia for a long time. Our phytochemical study of this fungus led to the identification of fourteen triterpenoids including four undescribed ones, and two pairs of undescribed phenolic enantiomers. The undescribed compounds were elucidated by extensive spectroscopic analysis including 1D and 2D NMR and HRESIMS, quantum chemical NMR and ECD calculations, as well as single-crystal X-ray diffraction analysis. Bioassays revealed that eight compounds showed dual inhibition against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) with IC50 values ranging from 2.40 ± 0.05 to 28.72 ± 0.46 µM, while 3ß-hydroxy-lanosra-8,24-dien-21-al and trametenolic acid only presented BuChE inhibitory activities with IC50 values of 22.21 ± 1.01 and 7.68 ± 0.13 µM, respectively. In the kinetic studies, the most active three compounds acted as non-competitive inhibitors for both cholinesterases. Furthermore, molecular docking simulations revealed that three compounds demonstrated dual-sites bounding to AChE/BuChE. These triterpenoids emerged as bivalent and dual inhibitors of AChE/BuChE and could be effective drug candidates to prevent and treat Alzheimer's disease in the future.

LC-MS-guided isolation of 2-(2-phenylethyl)chromone dimers from red soil agarwood of Aquilaria crassna.

Six new 2-(2-phenylethyl)chromone dimers (1-6) were isolated from ethyl ether extract of red soil agarwood of Aquilaria crassna from Vietnam by LC-MS-guided fractionation procedure. Their structures were unambiguously elucidated based on HRESIMS, 1D and 2D NMR spectra. The absolute configuration of 2-(2-phenylethyl)chromone dimers was determined by comparison of the experimental and computed ECD spectra. Compound 6 displayed cytotoxicity against the human myeloid leukemia cell line (K562) with an IC50 value of 39.49 µM.

New 2-(2-Phenylethyl)chromone derivatives from agarwood originating from Aquilaria sinensis.

Two new dimeric 2-(2-phenylethyl)chromones, aquilasinenones L and M (1 and 2), and one new monomer analogue, 5S, 6 R, 7S, 8 R-tetrahydroxy-[2-(3-methoxy-4-hydroxyphenyl)ethyl]- 5,6,7,8-tetrahydrochromone (3), together with two known compounds, were isolated from the artificial agarwood originating from Aquilaria sinensis. Compound 1 was the first structure found with C8-O-C4"' linkage among 2-(2-phenylethyl)chromone dimers. Their structures were unambiguously elucidated based on 1 D and 2 D NMR spectroscopy, as well as by comparison with the literature. The absolute configuration was determined by ECD calculation. None of the compounds exhibited acetylcholinesterase inhibitory activity.

Phenolic compounds from the sclerotia of Inonotus obliquus.

Three phenolic compounds (±1 and 2) including a pair of new enantiomers were isolated from the sclerotia of Inonotus obliquus. Their structures were assigned by extensive spectroscopic analyses. All the compounds were evaluated for the neuroprotective activity against oxidative damage on human neuroblastoma SH-SY5Y cells induced by H2O2. Compound 2 showed remarkable neuroprotective effect and significantly improved the cell viability of SH-SY5Y cells treated by H2O2.

A new picrotoxane-type sesquiterpene from Dendrobium nobile Lindl.

A picrotoxane-type sesquiterpene, dendroterpene E (1), together with five benzene derivatives (2-6), were isolated from the stems of Dendrobium nobile Lindl. Their structures were elucidated by spectroscopic analysis and X-ray diffraction analysis. Compound 1 was a new picrotoxane-type sesquiterpene with a C-9/C-1/O/C-11 oxetane ring, which was first encountered in this type of compounds. Compounds 1-3 exhibited inhibitory activities against α-glycosidase.

Genome-wide identification and expression analysis of terpene synthase gene family in Aquilaria sinensis.

Agarwood is the resinous portion of Aquilaria trees, and has been widely used as medicine and incense. Sesquiterpenes are the main chemical characteristic constituents of agarwood. Terpene synthase (TPS) is a critical enzyme responsible for biosynthesis of sesquiterpene compounds. However, limited information is available on genome-wide identification and characterization of the TPS family in Aquilaria trees. In this study, TPS gene family was identified and characterized in Aquilaria sinensis by bioinformatics methods. The expression of those genes was analyzed by RNA-seq and quantitative real-time PCR. Transcription factors regulating TPS gene expression were identified by yeast one-hybrid and dual-luciferase assay. In total, 26 AsTPS genes (AsTPS1-AsTPS26) were identified, which were classified into five subgroups. Many putative cis-elements putatively involved in stresses and phytohormones (especially jasmonic acid) were identified in the promoter regions of AsTPSs, suggesting that AsTPSs genes may be regulated by stresses and jasmonic acid. Expression analysis revealed seven TPS genes encoding sesquiterpene synthetases were induced by wounding and methyl jasmonic acid (MeJA), which may be related to sesquiterpene biosynthesis. By yeast one-hybrid screening, a ERF transcription factor AsERF1 was identified to interact with the AsTPS1 promoter. Subcellular localization analysis indicated AsERF1 was a nucleus-localized protein. Transient transfection of AsERF1 in leaves of Nicotiana benthamiana significantly enhanced the promoter activation of AsTPS1, suggesting AsERF1 may participate in sesquiterpene biosynthesis by regulating AsTPS1 expression. These data generated in this study provide a foundation for future studies on functional roles and regulation mechanisms of AsTPS in sesquiterpene biosynthesis and agarwood formation.

The Characteristic Fragrant Sesquiterpenes and 2-(2-Phenylethyl)chromones in Wild and Cultivated "Qi-Nan" Agarwood.

Recently, cultivated "Qi-Nan" (CQN) agarwood has emerged as a new high-quality agarwood in the agarwood market owing to its similar characteristics, such as high content of resin and richness in two 2-(2-phenylethyl)chromone derivatives, 2-(2-phenylethyl)chromone (59) and 2-[2-(4-methoxyphenyl)ethyl]chromone (60), to the wild harvested "Qi-Nan" (WQN) agarwood. In this study, we compared the chemical constituents and fragrant components of two types of WQN agarwood from A. agallocha Roxb. and A. sinensis, respectively, with CQN agarwood and ordinary agarwood varieties. Additionally, we analyzed different samples of WQN agarwood and CQN agarwood by GC-MS, which revealed several noteworthy differences between WQN and CQN agarwood. The chemical diversity of WQN was greater than that of CQN agarwood. The content of (59) and (60) was higher in CQN agarwood than in WQN agarwood. For the sesquiterpenes, the richness and diversity of sesquiterpenes in WQN agarwood, particularly guaiane and agarofuran sesquiterpenes, were higher than those in CQN. Moreover, guaiane-furans sesquiterpenes were only detected by GC-MS in WQN agarwood of A. sinensis and could be a chemical marker for the WQN agarwood of A. sinensis. In addition, we summarized the odor descriptions of the constituents and established the correlation of scents and chemical constituents in the agarwood.

Two new 2-phenylethylchromones from artificial agarwood by holing method.

Two new 2-(2-phenylethyl)chromone derivatives (1-2) were isolated from the ethyl acetate extract of artificial agarwood induced by holing method originating from Aquilaria sinensis (Lour.) Gilg, and they were isolated from this genus for the first time. The structures of these two new compounds were elucidated by extensive spectroscopic analyses, including UV, IR, one- and two-dimensional NMR and HRESIMS measurements. Bioassay tests of these two new compounds showed compounds 1 and 2 had weak inhibitory activity against acetylcholinesterase at a concentration of 50.0 µg/ml.

Three new dimeric 2-(2-phenylethyl)chromones from artificial agarwood of Aquilaria sinensis.

Three new dimeric 2-(2-phenylethyl)chromones crassin I ∼ K (1-3), together with one known analogue (4), were isolated from the artificial holing agarwood originating from Aquilaria sinensis. Their structures including the absolute configuration were elucidated by spectroscopic techniques (UV, IR, 1D and 2D NMR, ECD), and HRESIMS analysis, as well as by comparison with the literature data. Compounds 1 and 2 exhibited weak acetylcholinesterase inhibitory activity.

A new ergostane derivative from the leaves of Heynea trijuga Roxburgh.

During the course of searching for structurally interesting and bioactive compounds, a further chemical investigation of the leaves of Heynea trijuga Roxburgh was performed, which led to the isolation of a new ergostane derivative, named 3ß, 4ß, 20S-trihydroxyergosta-5, 24(28)-dien-16-one (1), together with five known sterides (3ß, 23S)-ergosta-5, 24(28)-diene-3, 23-diol (2), ergosta-5, 24(28)-diene-3ß-diol (3), stigmast-5-ene-3ß, 7α-diol (4), sitoindoside I (5) and stigmast-3ß, 5α, 6ß-triol (6). The structure of the new compound was elucidated using a combination of 1 D, 2 D NMR techniques and HR-EI-MS analyses. All the compounds were evaluated for cytotoxic activity against tumor cell line BEL-7402 by MTT method.

Three new 5,6,7,8-tetrahydro-2-(2-phenylethyl)chromones and one new dimeric 2-(2-phenylethyl)chromone from agarwood of Aquilaria crassna Pierre ex Lecomte in Laos.

Three new 5,6,7,8-tetrahydro-2-(2-phenylethyl)chromones and one new dimeric 2-(2-phenylethyl)chromone were isolated from the agarwood of Aquilaria crassna Pierre ex Lecomte in Laos. The structures of the isolates were elucidated by spectroscopic methods, and their configurations were determined via ROESY correlations, 3 J H-H coupling constants analyses, comparisons of chemical shifts and specific rotations with known compounds, and ECD calculation in the case of 1. Compounds 1-4 were evaluated for their cytotoxicity. Compounds 1 and 2 exhibited weak cytotoxicity toward HeLa cell line (IC50: 49.8 ± 1.2 µM) and K562 cell line (IC50: 42.66 ± 0.47 µM), respectively.