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.

Zizaane-Type Sesquiterpenoids and Their Rearranged Derivatives from Agarwood of an Aquilaria Plant.

Nine new sesquiterpenoids (1-9) were isolated from ethyl ether extract of agarwood originated from Aquilaria sp., including three novel sesquiterpenoids (1-3) derived from zizaane, together with six zizaane-type sesquiterpenoids (4-9). All structures were unambiguously elucidated based on 1D and 2D NMR spectra as well as by HRESIMS data. The absolute configuration of sesquiterpenoids was determined by comparison of the experimental and computed ECD spectra. In vitro anti-inflammatory assessment showed that compound 9 exhibited inhibition of NO production in LPS-stimulated RAW264.7 cells with an IC50 value of 62.22 ± 1.27 µM.

Two new sesquiterpenoids from agarwood originated from Aquilaria sp.

Two new sesquiterpenoids (1 and 2), together with two known sesquiterpenoids (3 and 4), were isolated from agarwood originated from Aquilaria sp. Their structures were elucidated by extensive spectroscopic methods including 1D and 2D NMR, IR, HRESIMS, and comparison with the literatures. All compounds were evaluated for cytotoxicity against five human cancer cell lines, but none of them displayed significant activity. [Formula: see text].

Sesquiterpenoids and 2-(2-phenylethyl)chromones respectively acting as α-glucosidase and tyrosinase inhibitors from agarwood of an Aquilaria plant.

The ethyl ether extract of agarwood from an Aquilaria plant afforded six new sesquiterpenoids, Agarozizanol A - F (1-6), together with four known sesquiterpenoids and six known 2-(2-phenylethyl)chromones. Their structures were elucidated via detailed spectroscopic analysis, X-ray diffraction, and comparisons with the published data. All the isolates were evaluated for the α-glucosidase and tyrosinase inhibitory activities in vitro. Compounds 5, 7, 8, and 10 showed significant inhibition of α-glucosidase with IC50 values ranging between 112.3 ± 4.5 and 524.5 ± 2.7 µM (acarbose, 743. 4 ± 3.3 µM). Compounds 13 and 14 exhibited tyrosinase inhibitory effect with IC50 values of 89.0 ± 1.7 and 51.5 ± 0.6 µM, respectively (kojic acid, 46.1 ± 1.3). In the kinetic studies, compounds 5 and 14 were found to be uncompetitive inhibitors for α-glucosidase and mixed type inhibitors for tyrosinase, respectively. Furthermore, molecular docking simulations revealed the binding sites and interactions of the most active compounds with α-glucosidase and tyrosinase.

Three New 2-(2-Phenylethyl)chromone Derivatives of Agarwood Originated from Gyrinops salicifolia.

Two new 2-(2-phenylethyl)chromone derivatives (1⁻2), comprising 5,6,7,8-tetrahydro-2-(2-phenylethyl)chromone and benzylacetone moieties, together with one new 2-(2-phenylethenyl)chromone (3) were isolated from the ethyl acetate extraction of agarwood originated from Gyrinops salicifolia Ridl. All structures were unambiguously elucidated on the basis of 1D and 2D NMR spectra as well as by HRESIMS data. All isolated compounds were tested for acetylcholinesterase (AChE) inhibitory activity and cytotoxic activity against human myeloid leukemia cell line (K562). However, none of the compounds displayed AChE inhibitory activity at a concentration of 50 µg mL-1 or cytotoxic activity against K562 cell line.

[Study on sesquiterpenes from agarwood originating from Gyrinops salicifolia].

Two sesquiterpenes were isolated from the agarwood originating from Gyrinops salicifolia with various chromatographic techniques, and their structures were determined as 12-hydroxy-dihydrocyperolone(1) and(rel)-4ß,5ß,7ß-eremophil-9-en-12,8α-olide(2), through a combined analysis of physicochemical properties and spectroscopic evidence. Compound 1 was a new compound. Compound 2 showed cytotoxicities against K562 and BEL-7401 cell lines, with IC_(50) values of(17.85±0.04) and(21.82±0.07) mg·L~(-1), respectively [taxol as positive control, with IC_(50) values of(1.97±0.11) and(6.31±0.08) mg·L~(-1)].

Two new 2-(2-Hydroxy-2-phenylethyl)chromens from agarwood originating from Aquilaria crassna.

Two new 2-(2-hydroxy-2-phenylethyl)chromones (1‒2), along with three known 2-(2-phenylethyl)chromones (3‒5), were isolated from the agarwood originating from Aquilaria crassna Pierre ex Lecomte. Their structures were determined by the spectroscopic methods including 1D and 2D NMR analysis and comparison with reported data in the literature. All the compounds were isolated from agarwood of A. crassna for the first time. Compounds 1 and 2 exhibited inhibitory activity against acetylcholinesterase (AChE) with 17.4 ± 0.6 and 15.8 ± 0.7%, respectively, at a concentration of 50 µg/ml. Besides, Compound 3 expressed antibacterial activities against Ralstonia solanacearum with diameter of the inhibition zone of 6.80 ± 0.08 mm at a concentration of 10 mg/ml.

Monitoring the Chemical Profile in Agarwood Formation within One Year and Speculating on the Biosynthesis of 2-(2-Phenylethyl)Chromones.

Agarwood is highly valued for its uses as incense, perfume, and medicine. However, systematic analyses of dynamic changes of secondary metabolites during the process of agarwood formation have not yet been reported. In this study, agarwood was produced by transfusing the agarwood inducer into the trunk of Aquilaria sinensis, and changing patterns of chemical constituents, especially 2-(2-phenylethyl)chromones (PECs), in wood samples collected from the 1st to 12th month, were analyzed by GC-EI-MS and UPLC-ESI-MS/MS methods. Aromatic compounds, steroids, fatty acids/esters, sesquiterpenoids, and PECs were detected by GC-MS, in which PECs were the major constituents. Following this, UPLC-MS was used for further comprehensive analysis of PECs, from which we found that 2-(2-phenylethyl)chromones of flindersia type (FTPECs) were the most abundant, while PECs with epoxidated chromone moiety were detected with limited numbers and relatively low content. Speculation on the formation of major FTPECs was fully elucidated in our context. The key step of FTPECs biosynthesis is possibly catalyzed by type III polyketide synthases (PKSs) which condensate dihydro-cinnamoyl-CoA analogues and malonyl-CoA with 2-hydroxy-benzoyl-CoA to produce 2-(2-phenyethyl)chromone scaffold, or with 2,5-dihydroxybenzoyl-CoA to form FTPECS with 6-hydroxy group, which may serve as precursors for further reactions catalyzed by hydroxylase or O-methyltransferase (OMT) to produce FTPECs with diverse substitution patterns. It is the first report that systematically analyzed dynamic changes of secondary metabolites during the process of agarwood formation and fully discussed the biosynthetic pathway of PECs.

A new 2-(2-phenylethyl)chromone glycoside in Chinese agarwood "Qi-Nan" from Aquilaria sinensis.

A new 2-(2-phenylethyl)chromone glycoside, 2-[2-(4-glucosyloxy-3-methoxyphenyl)ethyl]chromone (1), was isolated from the high-quality Chinese agarwood "Qi-Nan" originating from Aquilaria sinensis (Lour.) Glig. The structure including the absolute configuration of the sugar moiety was elucidated by spectroscopic techniques (UV, IR, 1D and 2D NMR), MS analysis, PMP-labeling HPLC analysis methods, as well as comparison with literature data. To the best of our knowledge, it is the first time that chromone glycoside was discovered in agarwood, or even in the whole Aquilaria plants.

[A new sesquiterpene from Chinese agarwood induced by artificial holing].

In order to study the chemical constituents of n-butanol fraction of ethanol extract from Chinese agarwood induced by artificial holing, various chromatographic techniques were carried out to isolate compounds, and the structures of compounds were determined through a combined analysis of physicochemical properties and spectroscopic evidence. Seven compounds were obtained and identified as selina-3,11-dien-9,15-diol (1), aquilarone D (2), 5α,6ß,7α,8ß-tetrahydroxy-2-[2-(2-hydroxyphenyl)ethyl]-5,6,7,8-tetrahydrochromone (3), 6,7-dimethoxy-2-[2-(4-methoxyphenyl)ethyl]chromone (4), syringin (5), methyl (Z)-p-coumarate (6), and 4'-methoxycinnamic acid (7), among which compound 1 was a new compound and compounds 5-7 were isolated from agarwood for the first time. The bioactivity assay results concluded that compounds 6 and 7 showed certain nematicidal activity against Panagrellus redivivus, and compounds 4, 6 and 7 exhibited cytotoxicity against BEL-7402, SGC-7901 and A549 carcinoma cell lines.

Sesquiterpenoids from Chinese Agarwood Induced by Artificial Holing.

Two new sesquiterpenoids, 3-oxo-7-hydroxylholosericin A (1) and 1,5;8,12-diepoxy-guaia-12-one (2), together with seven known sesquiterpenoids 3-9, were isolated from Chinese agarwood induced by artificial holing originating from Aquilaria sinensis (Lour.) Gilg. Their structures were identified by spectroscopic techniques (UV, IR, 1D and 2D NMR) and MS analyses. The absolute configuration of compound 1 was determined by comparison of its measured CD curve with that of calculated data for 1 and ent-1. The NMR data of 3 were reported in this study for the first time. Compounds 1, 2, 4-6, together with the EtOAc extract showed moderate inhibitory activities against acetylcholinesterase, and compounds 4-6, 8 exhibited antibacterial activities against Staphylococcus aureus or Ralstonia solanacearum.

2-(2-Phenylethyl)chromone Derivatives of Agarwood Originating from Gyrinops salicifolia.

Three new2-(2-phenylethyl)chromone derivatives (1-3) and a new2-(2-phenylethenyl)chromone derivative (4), together with two known 2-(2-phenylethyl)chromone derivatives (5-6), were isolated from agarwood originating from Gyrinops salicifolia Ridl. The structures of compounds 1-4 were elucidated by comprehensive spectroscopic techniques (UV, IR, 1D and 2D-NMR) and MS analysis, as well as by comparison with the literature. Compounds 1, 2, and 5 showed moderate cytotoxicity against human tumor K562, BEL-7402, and SGC-7901 cell lines with IC50 values of 5.76 to 20.1 µM.

Two new terpenoids from the stems of Manihot esculenta.

A new eremophilane sesquiterpene, sporogen AO-2 (1), and a new beyerane diterpene, thecacorin C (2), together with two known compounds, longifoamide-B (3) and methylcholestane-3ß,5α,6ß-triol (4), were isolated from the stems of Manihot esculenta. The structures of the two new compounds were determined by spectroscopic techniques (UV, IR, MS, 1D, and 2D NMR). Antimicrobial assay showed that compound 3 possessed modest inhibitory effects on Saphylococcus aureus and methicillin-resistant S.aureus, diameters of inhibition zones of which were 7.5 and 8.0 mm, respectively. Compound 4 possessed modest inhibitory effect on S. aureus, the diameter of inhibition zone of which was 6.8 mm.

A new apotirucallane-type triterpenoid from Atalantia buxifolia.

A new triterpenoid (1) with apotirucallane skeleton was isolated from the ethanol extract of the roots of Atalantia buxifolia (Poir.) Oliv. The complete structural assignment of the new compound was elucidated by a combination of 1D, 2D NMR (HMQC, HMBC, COSY, and NOESY), and HR-ESI-MS analysis. Moreover, this new compound was evaluated in vitro for its cytotoxic, antimicrobial and enzymes inhibitory activities.

Monoterpenoid coumarins from the peels of Clausena lansium.

A phytochemical investigation on the peels of Clausena lansium (Lour.) Skeels led to the isolation of two new monoterpenoid coumarins, named clauslactone V (1) and clauslactone W (2), together with three known analogues (3-5). Their structures were elucidated by spectroscopic techniques (UV, IR, MS, 1D and 2D NMR). All the compounds were evaluated for hypoglycemic activity, and compounds 1-5 showed α-glucosidase inhibitory activity in vitro.

A new 2-(2-phenylethyl)chromone derivative in Chinese agarwood 'Qi-Nan' from Aquilaria sinensis.

Phytochemical analysis of the high quality Chinese agarwood 'Qi-Nan' originating from Aquilaria sinensis (Lour.) Glig led to the isolation of a new 2-(2-phenylethyl)chromone derivative, qinanones G (1), and four known 2-(2-phenylethyl)chromones (2-5). Their structures were elucidated by spectroscopic techniques (UV, IR, 1D and 2D NMR) and MS analyses. The NMR data of chromones 1-3 were first reported, and chromones 2 and 3 showed weak inhibitory activity against acetylcholinesterase.

Carbazole alkaloids from the peels of Clausena lansium.

A new carbazole alkaloid, claulansine K (1), together with six known carbazole alkaloids (2-7), was isolated from the peels of Clausena lansium (Lour.) Skeels. The new compound was elucidated using a combination of 1D and 2D NMR (HMQC, HMBC, COSY, and ROESY) techniques, and HR-EI-MS analyses. Compound 1 showed in vitro α-glucosidase inhibitory activity with the IC50 value of 0.11 mM. Compound 2 exhibited moderate antibacterial activity against Staphylococcus aureus with the diameter of inhibition zone of 14.2 mm.

Three new phenolic compounds from Dalbergia odorifera.

Three new phenolic compounds (1-3) were isolated from the heartwood of Dalbergia odorifera T. Chen. (Leguminosae). Their structures were established based on spectroscopic methods including 1D and 2D NMR (HSQC, COSY, HMBC and ROESY). Compound 2 exhibited cytotoxicity against BEL-7402 tumor cell lines.

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.

2-(2-phenylethyl)chromone derivatives in Chinese agarwood "Qi-Nan" from Aquilaria sinensis.

Five new 2-(2-phenylethyl)chromone derivatives, qinanones A-E (1-5), together with eight known 2-(2-phenylethyl)chromone derivatives (6-13), were isolated from the Et2O extract of high-quality Chinese agarwood "Qi-Nan" originating from Aquilaria sinensis. The structures of the new 2-(2-phenylethyl)chromones were elucidated by spectroscopic techniques (UV, IR, 1D and 2D NMR) and MS analyses. In the bioassay for acetylcholinesterase inhibitors, compounds 1-6, 10, and 12 exhibited weak inhibitory activities (inhibition percentage ranged from 10 % to 24 % at the concentration of 50 µg/mL). Compared with other agarwoods, "Qi-Nan" was different in containing 2-(2-phenylethyl)chromones with unsubstituted chromone rings.