Antidepressant abietane diterpenoids from Chinese eaglewood

Solid-Phase Microextraction/Gas Chromatography-Time-of-Flight Mass Spectrometry Approach Combined with Network Pharmacology Analysis to Evaluate the Quality of Agarwood from Different Regions against Anxiety Disorder

Agarwood (Aquilaria malaccensis Lam.) is a resinous material from different geographical locations. The current evaluation of agarwood quality is usually based on its physical properties and chemical compounds, yet only a few studies have linked agarwood quality with its anxiolytic effect, as indicated by characteristic compounds. In this study, using solid-phase microextraction/gas chromatography-time-of-flight mass spectrometry (SPME/GC-TOFMS) and multivariate analysis, we found 116 significantly different compounds in agarwood samples from four locations in Southeast Asia with regard to their quality. Brunei and Nha Trang agarwood had abundant sesquiterpenoids, exhibiting notable pharmacological efficacy in relieving anxiety. Malaysian and Irian agarwood had abundant alcohols and aldehydes, qualifying them as high-quality spices. Compound-target-disease network and pathway enrichment analysis were further employed to predict 79 gene targets and 20 pathways associated with the anxiolytic effects based on the 62 sesquiterpenoids. The correlated relationships among the sesquiterpenoids and targets suggest that agarwood treats anxiety via multiple compounds acting on multiple targets. Varying levels of sesquiterpenes across agarwood groups might lead to differences in the anxiolytic effects via signaling pathways, such as neurotransmitter- and hormone-regulated pathways. Our study originally evaluates agarwood quality and its anxiolytic effect by linking the characteristic compounds to potential gene targets and pathways.

Chemical constituents from Abies chensiensis and their antifungal activity

One new (1) and six known cycloartane triterpenoids (2-7), along with seven reported abietane diterpenoids (8-14), were isolated from the bark of the branches of Abies chensiensis, of which compounds 2-14 were also received for the first time from the genus of Abies. Structural elucidation of all the compounds was carried out by extensive spectroscopic analyses. Additionally, the antifungal activity of isolated compounds 2-13 was evaluated by inhibiting the growth of fungal mycelium. Among them, compounds 8 and 10 demonstrated obvious inhibitory activity against plant pathogens Fusarium avenaceum and Bipolaris sorokiniana.

Agarwood essential oil inhalation exerts antianxiety and antidepressant effects via the regulation of Glu/GABA system homeostasis

Depression and anxiety are common diseases that endanger the physical and mental health of individuals. Agarwood incense inhalation has been used as a traditional Chinese medicine for relaxation and to improve sleep for centuries. In a previous study by the authors it was demonstrated that agarwood essential oil (AEO) injection exerted anxiolytic and antidepressant effects. Therefore the present study further investigated the anxiolytic and antidepressant effects of AEO inhalation on anxiolytic mice induced by M-chlorophenylpiperazine and depressive mice induced by chronic unpredictable mild stress. The results demonstrated that AEO exerted a significant anxiolytic effect, whereby autonomous movements were inhibited during the light dark exploration test and open field test. Furthermore, the tail suspension test and the forced swimming test demonstrated that AEO also exerted an antidepressant effect, whereby the immobility times were decreased. Moreover, AEO was determined to increase the levels of 5-hydroxytryptamine, γ-aminobutyric acid (GABA) A receptor (GABA_A) and glutamate (Glu) in anxiolytic mice and inhibit the levels of GABA_A and Glu in depressive mice. Further investigations into how AEO affected the Glu/GABA system demonstrated that AEO markedly increased the protein expression levels of GABA transaminase (GABAT), glutamate metabotropic receptor 5 (GRM5), glutamate ionotropic receptor AMPA type subunit 1 (GluR1) and vesicular glutamate transporter 1 (VGluT1). Furthermore, AEO reduced the expression levels of GABAT, glutamate ionotropic receptor NMDA type subunit 2B and GRM5, and enhanced the expression levels of GluR1 and VGluT1. These results demonstrated that AEO potentially possesses antianxiety and antidepressant properties. The present study determined that the mechanism was related to the regulation of Glu/GABA neurotransmitter system homeostasis.

Diterpenes from Pinus kesiya var. langbianensis (A.Chev.) Gaussen ex Bui (Pinaceae) and their protective effects in LPS-treated BEAS-2B cells

Eight previously undescribed diterpenoids, rosins A-H, and nine known diterpenoids were isolated from the resin from Pinus kesiya var. langbianensis (A.Chev.) Gaussen ex Bui (Pinaceae) extracted with 95% ethanol. Their structures were determined by nuclear magnetic resonance spectroscopy, mass spectrometry, J-based configuration analysis (JBCA), NOESY spectra, calculated NMR chemical shifts and electronic circular dichroic (ECD) spectra. All compounds were evaluated for their protective effects in LPS-treated human normal lung epithelial cells (BEAS-2B), and the cell viability was significantly increased after treatment with compounds 5, 10, 12, or 15 at a concentration of 10 μM.

Agarwood-The Fragrant Molecules of a Wounded Tree

Agarwood, popularly known as oudh or gaharu, is a fragrant resinous wood of high commercial value, traded worldwide and primarily used for its distinctive fragrance in incense, perfumes, and medicine. This fragrant wood is created when Aquilaria trees are wounded and infected by fungi, producing resin as a defense mechanism. The depletion of natural agarwood caused by overharvesting amidst increasing demand has caused this fragrant defensive resin of endangered Aquilaria to become a rare and valuable commodity. Given that instances of natural infection are quite low, artificial induction, including biological inoculation, is being conducted to induce agarwood formation. A long-term investigation could unravel insights contributing toward Aquilaria being sustainably cultivated. This review will look at the different methods of induction, including physical, chemical, and biological, and compare the production, yield, and quality of such treatments with naturally formed agarwood. Pharmaceutical properties and medicinal benefits of fragrance-associated compounds such as chromones and terpenoids are also discussed.

Aquilaria Species (Thymelaeaceae) Distribution, Volatile and Non-Volatile Phytochemicals, Pharmacological Uses, Agarwood Grading System, and Induction Methods

Agarwood is a highly valuable fragrant wood of Aquilaria spp. (Thymelaeaceae) which has been widely utilized in traditional medicine, religious rites, and cultural activities. This study summarizes a review on the identification of Aquilaria cultivars, volatile and non-volatile phytochemicals, pharmacological uses, and agarwood grading system to determine its quality, and different agarwood induction methods. Due to the highly demanding and depleted natural resources, the research on agarwood is still insufficient, and it has broad research and development prospects in many industries. However, due to the significant scientific nature of agarwood application, developing high-quality products and drugs from agarwood have become highly important, while no one has discussed in detail the phytochemicals uses and provided a summary until now. The main phytochemicals of agarwood include terpenoids, dominated by sesquiterpenes. For centuries, terpenoids have been used in traditional Chinese medicine and have been shown to possess various pharmacological properties, including bacteriostatic, antibacterial, sedation, analgesia, anti-inflammation, anti-asthmatic, hypoglycemic, antidepressant, and many others. Alongside biological activity screening, phytochemical advances and pharmacological research have also made certain progress. Therefore, this review discusses the research progress of agarwood in recent years and provides a reference basis for further study of Aquilaria plants and agarwood.

Diterpenoids with Aromatase Inhibitory Activity from the Rhizomes of Kaempferia elegans

Investigation of bioactive compounds from the rhizomes of Kaempferia elegans led to the isolation and characterization of ten new diterpenoids, namely, five 12,13-seco-diterpenoids named elegansins A-E (1-5) and five new abietanes, elegansols A-E (6-10), together with seven known diterpenoids (11-17). The structure elucidation of the new compounds was achieved by HRESIMS, NMR, and ECD spectroscopic analysis. Compounds (1-5) are the first examples of 12,13-seco-diterpenoid-type compounds representing a decalin fused dihydropyran skeleton. Plausible biosynthetic pathways for compounds 1-5 are proposed. Aromatase inhibitory activities of all compounds were evaluated, and abieta-8,11,13-trien-11-ol (16) was found to be the most potent aromatase inhibitor with an IC₅₀ value of 3.7 μM.

Neuroprotective compounds from the resinous heartwood of Aquilaria sinensis

Six undescribed compounds, including three sesquiterpenoids [(4S,5S,7S,8S,11R)-7-hydroxyguai-1(10)-en-8,12-olide, aquilarisinone, and 2Z,7(13),9E-humulatrien-12-ol-5-one], one diphenylpentanone [1-(2-hydroxyphenyl)-5-phenylpentan-3-one], and two 2-(2-phenylethyl)chromones (6-epiagarotetrol and triepoxyhexahydrochromone A), along with 15 known compounds, were isolated from the resinous heartwood of Aquilaria sinensis (Thymelaeaceae). Their structures were determined by mass (MS) and nuclear magnetic resonance (NMR) spectroscopic data. The absolute configuration of (4S,5S,7S,8S,11R)-7-hydroxyguai-1(10)-en-8,12-olide was confirmed by X-ray diffraction analysis, and the configurations of (4S,7S,8S,10R,11R)-7,10-epoxyguai-1(5)-en-8,12-olide, aquilarisinone, 6-epiagarotetrol, and triepoxyhexahydrochromone A were confirmed by electronic circular dichroism (ECD) calculations. The neuroprotective activities of the compounds were evaluated using models of BACE1 inhibition and PC12 cells with corticosterone- and 1-methyl-4-phenylpyridine ion (MPP⁺)-induced damage. At concentrations of 1, 2, and 5 μM, triepoxyhexahydrochromone A, (+)-(7R,10R)-selina-4,11(13)-diene-12,15-dial, (-)-(5R,7R,10R)-12,15-dioxo-α-selinene, and (+)-(1R,4S,5R)-1β-hydroxyeremophila-7(11),9-dien-8-one exerted significant protective effects (p < 0.01) on PC12 cell injury induced by corticosterone, while triepoxyhexahydrochromone A and (-)-(5R,7R,10R)-12,15-dioxo-α-selinene exerted significant protective effects (p < 0.01) on MPP⁺-induced PC12 cell injury at concentrations of 1, 2, and 5 μM. No compounds produced significant inhibitory effects on BACE1, with inhibition rates of less than 20% observed at a concentration of 20 μM.

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.

The protective effects of Aquilariae Lignum Resinatum extract on 5-Fuorouracil-induced intestinal mucositis in mice

BACKGROUND

Aquilariae Lignum Resinatum as a traditional Chinese medicine is used in prescription for treatment of gastrointestinal diseases. Phytochemical investigations show that there are many anti-ulcer and anti-inflammatory ingredients in A. agallocha methanol extract (AEE). However, scarce data is available about the constituents absorbed into the blood, activity and mechanisms of AEE on intestinal mucositis.

HYPOTHESIS/PURPOSE

To analyze the bioactive constituents of AEE absorbed in the blood, and further explore the potential mechanisms of the protection against chemotherapy-induced intestinal mucositis.

METHODS

The serum pharmacochemistry using UHPLC-Q-TOF/MS was performed to screen the bioactive compounds of AEE absorbed in serum. The intestinal mucositis was induced by 5-Fuorouracil (5-Fu) and treated with AEE. The severity of intestinal mucositis was evaluated based on body weight, food-intake and diarrhea. Furthermore, the mechanism of AEE was investigated involved in the pathogenesis of mucositis on repairing injury of intestinal mucosa, immune functions, and inflammatory response.

RESULTS

Altogether, 11 components were identified or tentatively characterized in dosed plasma. In pharmacodynamics study, intestinal mucositis caused by 5-Fu was effectively attenuated after AEE treatment. AEE treatment improved food-intake and injury of the intestinal mucosa, relieved body weight loss and severe diarrhea through up-regulating expression of proliferating cell nuclear antigen (PCNA) and inhibiting the levels of cyclooxygenase-2 (COX-2) and tumor necrosis factor-α (TNF-α) in ileum segments.

CONCLUSIONS

AEE protected against 5-Fu-induced intestinal mucositis (IM) in mice through mechanisms that involved in promoting the enterocyte proliferative activity, maintaining the integrity of tight junction proteins, inhibiting oxidative stress and ameliorating the inflammatory disturbances. Accordingly, A. agallocha may be a promising therapeutic candidate used for the prevention of IM during cancer chemotherapy.

Aquilariaenes A-H, eight new diterpenoids from Chinese eaglewood

Aquilariaenes A-H (1-8), eight new diterpenoids and nor-diterpenoids (1-8) belonging to abietane or pimarane, were isolated from the petroleum ether extract of Chinese eaglewood. Their structures were elucidated on the basis of extensive spectroscopic methods including HRESIMS, IR, 1D and 2D NMR spectroscopic data analyses. Antidepressant activities of isolates for in vitro inhibition of serotonin and norepinephrine reuptake in rat brain synaptosomes were evaluated.

Agarwood Essential Oil Ameliorates Restrain Stress-Induced Anxiety and Depression by Inhibiting HPA Axis Hyperactivity

In our previous investigation, we found that agarwood essential oil (AEO) has a sedative-hypnotic effect. Sedative-hypnotic drugs usually have an anxiolytic effect, where concomitant anxiety and depression are a common comorbidity. Therefore, this study further investigated the anxiolytic and antidepressant effects of AEO using a series of animal behavior tests on a restraint stress-induced mice model. The elevated plus maze (EPM) test, the light dark exploration (LDE) test, and the open field (OF) test demonstrated that AEO has a significant anxiolytic effect. Simultaneously, the tail suspension (TS) test and the forced swimming (FS) test illuminated that AEO has an antidepressant effect with the immobility time decreased. Stress can cause cytokine and nitric oxide (NO) elevation, and further lead to hypothalamic-pituitary-adrenal (HPA) axis hyperactivity. AEO was shown to dose-dependently inhibit the levels of cytokines, including interleukin 1α (IL-1α), IL-1β, and IL-6 in serum, significantly decrease the mRNA level of neural nitric oxide synthase (nNOS) in the cerebral cortex and hippocampus, and inhibit the nNOS protein level in the hippocampus. Concomitant measurements of the HPA axis upstream regulator corticotropin releasing factor (CRF) and its receptor CRFR found that AEO significantly decreases the gene expression of CRF, and significantly inhibits the gene transcription and protein expression of CRFR in the cerebral cortex and hippocampus. Additionally, AEO dose-dependently reduces the concentrations of adrenocorticotropic hormone (ACTH) and corticosterone (CORT) downstream of the HPA axis, as measured by ELISA kits. These results together demonstrate that AEO exerts anxiolytic and antidepressant effects which are related to the inhibition of CRF and hyperactivity of the HPA axis.

Catalytic, Tunable, One-Step Bismuth(III) Triflate Reaction with Alcohols: Dehydration Versus Dimerization

Bi(OTf)₃·xH₂O is a powerful catalyst for the dehydration of tertiary alcohols into alkenes in apolar solvents. The reaction proceeds smoothly and selectively, with amounts as low as 0.01 mol % catalyst, in yields up to 93%. Moreover, in polar solvents, Bi(OTf)₃·xH₂O (0.1-1 mol %) selectively catalyzes the dimerization of the alcohols instead, forming new C-C bonds, in yields up to 96%. This mild, efficient, economic, and eco-friendly method is applicable across different chemical classes and amenable to several functional groups.

Chemical Constituents and Pharmacological Activity of Agarwood and Aquilaria Plants

Agarwood, a highly precious non-timber fragrant wood of Aquilaria spp. (Thymelaeaceae), has been widely used in traditional medicine, religious rites, and cultural activities. Due to the inflated demanding and depleted natural resources, the yields of agarwood collected from the wild are shrinking, and the price is constantly rising, which restricts agarwood scientific research and wide application. With the sustainable planting and management of agarwood applied, and especially the artificial-inducing methods being used in China and Southeast Asian countries, agarwood yields are increasing, and the price is becoming more reasonable. Under this condition, illuminating the scientific nature of traditional agarwood application and developing new products and drugs from agarwood have become vitally important. Recently, the phytochemical investigations have achieved fruitful results, and more than 300 compounds have been isolated, including numerous new compounds that might be the characteristic constituents with physiological action. However, no one has focused on the new compounds and presented a summary until now. Alongside phytochemical advances, bioactivity screening and pharmacological investigation have also made a certain progress. Therefore, this review discussed the new compounds isolated after 2010, and summarized the pharmacological progress on agarwood and Aquilaria plants.

Review: Secondary Metabolites of Aquilaria, a Thymelaeaceae Genus

Background:

Aquilaria, a genus belonging to the Thymelaeaceae, produces fragrant resinous agarwood, also known as eaglewood, which has been used as incense since old times. The intense fra-grance is the result of the presence of a wide variety of secondary metabolites.

Objective:

This genus was reported contained sesquiterpenes, chromones, flavonoids, benzophenones, diterpenoids, triterpenoids, and lignans.

Conclusion:

Here, we review the different secondary metabolites that have been identified in Aquilaria to show their diversity and to allow comparison with other Thymelaeaceae genera.

Diterpenoids from Croton crassifolius include a novel skeleton possibly generated via an intramolecular [2+2]-photocycloaddition reaction

Five previously undescribed terpenoids (cracrosons D-H), including three clerodane diterpenoids, together with 16 known diterpenoids were isolated from Croton crassifolius (Euphorbiaceae). Cracroson D features a previously undescribed carbon skeleton with an unprecedented cyclobutane ring. Their structures, including their absolute configurations, were elucidated using spectroscopic and single-crystal X-ray diffraction analyses along with CD calculations. A plausible biogenetic pathway for cracroson D is also proposed, which was supported by the experimental results. Additionally, all of the compounds were evaluated in vitro for cytotoxicity against T24 and A549 cells using the CCK-8 method.

Aquilanols A and B, Macrocyclic Humulene-Type Sesquiterpenoids from the Agarwood of Aquilaria malaccensis

Four new and five known sesquiterpenoids were isolated from the agarwood of Aquilaria malaccensis. Aquilanols A and B (1 and 2) have an unprecedented macrocyclic humulene structure with a bicyclic 7/10 ring system. Compound 2 was obtained as a scalemic mixture that was resolved by HPLC analysis using a chiral column. Their structures were deduced based on spectroscopic data analysis, and the absolute configurations were unambiguously determined by X-ray crystallographic data and ECD spectroscopic analysis. A putative biosynthetic pathway of these sesquiterpenoids is proposed.

Pseudo-Natural Products, Some Artefacts Formed during the Isolation of Terpenoids

The formation of artefacts during the isolation, purification and characterisation of terpenoids is reviewed.

Antiallergic Phorbol Ester from the Seeds of Aquilaria malaccensis

The Aquilaria malaccensis (Thymelaeaceae) tree is a source of precious fragrant resin, called agarwood, which is widely used in traditional medicines in East Asia against diseases such as asthma. In our continuous search for active natural products, A. malaccensis seeds ethanolic extract demonstrated antiallergic effect with an IC₅₀ value less than 1 µg/mL. Therefore, the present research aimed to purify and identify the antiallergic principle of A. malaccensis through a bioactivity-guided fractionation approach. We found that phorbol ester-rich fraction was responsible for the antiallergic activity of A. malaccensis seeds. One new active phorbol ester, 12-O-(2Z,4E,6E)-tetradeca-2,4,6-trienoylphorbol-13-acetate, aquimavitalin (1) was isolated. The structure of 1 was assigned by means of 1D and 2D NMR data and high-resolution mass spectrometry (HR-MS). Aquimavitalin (1) showed strong inhibitory activity in A23187- and antigen-induced degranulation assay with IC₅₀ values of 1.7 and 11 nM, respectively, with a therapeutic index up to 71,000. The antiallergic activities of A. malaccensis seeds and aquimavitalin (1) have never been revealed before. The results indicated that A. malaccensis seeds and the pure compound have the potential for use in the treatment of allergy.

Three New Sesquiterpenoids and One New Sesquiterpenoid Derivative from Chinese Eaglewood

Three new sesquiterpenoids (1-3) and one new sesquiterpenoid derivative (4), along with three known sesquiterpenoids (5-7), were isolated from the 95% ethanolic extract of Chinese eaglewood [Aquilaria sinensis (Lour.) Gilg]. The structures of these compounds were elucidated through extensive analysis of spectroscopic data including IR, NMR, HRESIMS, and X-ray diffraction experiments. In addition, the above new compounds were detected for their bioactivities against LPS-induced NO production in RAW 264.7 cells. Among them, compound 2 exhibited obvious anti-inflammatory activity with an IC50 value of 8.1 μM.

Bioactive Diterpenoids from the Leaves of Callicarpa macrophylla

A phytochemical investigation of the leaves of Callicarpa macrophylla led to the isolation of five new diterpenoids (1-5), macrophypenes A-E, and nine known analogues (6-14). The structures of 1-5 were established on the basis of extensive analysis of NMR spectroscopic data, X-ray diffraction data, and experimental and calculated electronic circular dichroism spectra. Compound 1 is a spiroditerpenoid with a novel skeleton, and compound 5 is a rare ent-abietane diterpenoid possessing a peroxide bridge. Compounds 1, 5-7, and 11-14 stimulate nerve growth factor mediated neurite outgrowth from PC12 cells.

Aromatic abietane diterpenoids: their biological activity and synthesis

In this study, the biological properties of abietane-type diterpenoids with an aromatic C ring are reviewed. The review contains about 160 references.

Diterpenoids of terrestrial origin

This review covers the isolation and chemistry of diterpenoids from terrestrial as opposed to marine sources and includes labdanes, clerodanes, pimaranes, abietanes, kauranes, gibberellins, cembranes and their cyclization products. The literature from January to December 2013 is reviewed.

Chemical constituents of Abies nukiangensis

During a survey on chemical constituents of Abies nukiangensis, seven previously unreported compounds, including six triterpenes (1-6) and one phenol (7) were isolated and characterized, together with 37 known miscellaneous chemical constituents. The structures of compounds 1-7 were established mainly by extensive analysis of the 1D and 2D NMR, as well as HRMS data. The absolute configurations of compounds 1 and 8 were confirmed unambiguously by the Cu-Kα X-ray crystallography. Compounds 3 and 8-10 showed significant anti-hepatitis C virus effects with EC50 values of 3.73, 2.67, 1.33 and 2.25μM, respectively.

Synthesis of a dicyano abietane, a key intermediate for the anti-inflammatory agent TBE-31

The synthesis of dicyano abietane 11, a potential precursor to the biologically active tricyclic bis-cyano enone 6 (TBE-31), was accomplished in eight steps from epoxide 13. The synthesis features a Lewis acid promoted stereoselective cyclization of epoxide 13 to generate the tricyclic ring system 12 in one step.