New Flavones, a 2-(2-Phenylethyl)-4H-chromen-4-one Derivative, and Anti-Inflammatory Constituents from the Stem Barks of Aquilaria sinensis

Identification of O-Methyltransferases Potentially Contributing to the Structural Diversity of 2-(2-Phenylethyl)chromones in Agarwood

2-(2-Phenylethyl)chromones (PECs) are the primary constituents responsible for the promising pharmacological activities and unique fragrance of agarwood. However, the O-methyltransferases (OMTs) involved in the formation of diverse methylated PECs have not been reported. In this study, we identified one Mg2+-dependent caffeoyl-CoA-OMT subfamily enzyme (AsOMT1) and three caffeic acid-OMT subfamily enzymes (AsOMT2-4) from NaCl-treated Aquilaria sinensis calli. AsOMT1 not only converts caffeoyl-CoA to feruloyl-CoA but also performs nonregioselective methylation at either the 6-OH or 7-OH position of 6,7-dihydroxy-PEC. On the other hand, AsOMT2-4 preferentially utilizes PECs as substrates to produce structurally diverse methylated PECs. Additionally, AsOMT2-4 also accepts nonPEC-type substrates such as caffeic acid and apigenin to generate methylated products. Protein structure prediction and site-directed mutagenesis revealed that residues of L313 and I318 in AsOMT3, as well as S292 and F313 in AsOMT4 determine the distinct regioselectivity of these two OMTs toward apigenin. These findings provide important biochemical evidence of the remarkable structural diversity of PECs in agarwood.

Comparative Analysis of Metabolome and Transcriptome in Different Tissue Sites of Aquilaria sinensis (Lour.) Gilg

The resinous stem of Aquilaria sinensis (Lour.) Gilg is the sole legally authorized source of agarwood in China. However, whether other tissue parts can be potential substitutes for agarwood requires further investigation. In this study, we conducted metabolic analysis and transcriptome sequencing of six distinct tissues (root, stem, leaf, seed, husk, and callus) of A. sinensis to investigate the variations in metabolite distribution characteristics and transcriptome data across different tissues. A total of 331 differential metabolites were identified by chromatography-mass spectrometry (GC-MS), of which 22.96% were terpenoids. The differentially expressed genes (DEGs) in RNA sequencing were enriched in sesquiterpene synthesis via the mevalonate pathway. The present study establishes a solid foundation for exploring potential alternatives to agarwood.

From Plant to Chemistry: Sources of Antinociceptive Non-Opioid Active Principles for Medicinal Chemistry and Drug Design

Pain is associated with many health problems and a reduced quality of life and has been a common reason for seeking medical attention. Several therapeutics are available on the market, although side effects, physical dependence, and abuse limit their use. As the process of pain transmission and modulation is regulated by different peripheral and central mechanisms and neurotransmitters, medicinal chemistry continues to study novel ligands and innovative approaches. Among them, natural products are known to be a rich source of lead compounds for drug discovery due to their chemical structural variety and different analgesic mechanisms. Numerous studies suggested that some chemicals from medicinal plants could be alternative options for pain relief and management. Previously, we conducted a literature search aimed at identifying natural products interacting either directly or indirectly with opioid receptors. In this review, instead, we have made an excursus including active ingredients derived from plants whose mechanism of action appears from the literature to be other than the modulation of the opioid system. These substances could, either by themselves or through synthetic and/or semi-synthetic derivatives, be investigated in order to improve their pharmacokinetic characteristics and could represent a valid alternative to the opioid approach to pain therapy. They could also be the basis for the study of new mechanisms of action in the approach to this complex and disabling pathology.

Discovery of anti-inflammatory natural flavonoids: Diverse scaffolds and promising leads for drug discovery

Natural products have been utilized for medicinal purposes for millennia, endowing them with a rich source of chemical scaffolds and pharmacological leads for drug discovery. Among the vast array of natural products, flavonoids represent a prominent class, renowned for their diverse biological activities and promising therapeutic advantages. Notably, their anti-inflammatory properties have positioned them as promising lead compounds for developing novel drugs combating various inflammatory diseases. This review presents a comprehensive overview of flavonoids, highlighting their manifold anti-inflammatory activities and elucidating the underlying pathways in mediating inflammation. Furthermore, this review encompasses systematical classification of flavonoids, related anti-inflammatory targets, involved in vitro and in vivo test models, and detailed statistical analysis. We hope this review will provide researchers engaged in active natural products and anti-inflammatory drug discovery with practical information and potential leads.

Investigating the potential anti-inflammatory mechanism of benzophenone compounds from the leaves of Aquilaria sinensis (Lour.) Gilg based on network pharmacology and molecular docking strategies

BACKGROUND

Aquilaria sinensis (Lour.) Gilg (ASG) has been used as traditional medicine for centuries. However, the active ingredients from leaves and their anti-inflammatory mechanism are rarely reported. The network pharmacology and molecular docking strategies were applied to explore the potential mechanisms of Benzophenone compounds from the leaves of ASG (BLASG) against inflammation.

METHODS

BLASG-related targets were obtained from the SwissTargetPrediction and PharmMapper databases. Inflammation-associated targets were retrieved from GeneGards, DisGeNET, and CTD databases. Cytoscape software was used to draw a network diagram of BLASG and its corresponding targets. DAVID database was applied for enrichment analyses. A protein-protein interaction (PPI) network was constructed to identify the hub targets of BLASG. Molecular docking analyses were performed by AutoDockTools 1.5.6. Moreover, we used ELISA and qRT-PCR assays to validate the anti-inflammatory effects of BLASG by cell experiments.

RESULTS

Four BLASG were extracted from ASG, and corresponding 225 potential targets were identified. PPI network analysis indicated that SRC, PIK3R1, AKT1, and other targets were the core therapeutic targets. Enrichment analyses revealed that the effects of BLASG are regulated by targets associated with apoptosis and inflammation-related pathways. In addition, molecular docking revealed that BLASG combined well with PI3K and AKT1. Furthermore, BLASG significantly decreased the inflammatory cytokines levels and down-regulated PIK3R1 and AKT1 gene expression in RAW264.7 cells.

CONCLUSION

Our study predicted the potential targets and pathways of BLASG against inflammation, which offered a promising strategy to reveal the therapeutic mechanism of natural active components in the treatment of diseases.

Comprehensive Comparisons between Grafted Kynam Agarwood and Normal Agarwood on Traits, Composition, and In Vitro Activation of AMPK

Agarwood, a highly valuable resin/wood combination with diverse pharmacological activities but scarce supply, has a long history of being used as a medicine in several medical systems. Grafted Kynam agarwood (GKA) has been cultivated successfully recently and has the qualities meeting the definition of premium Kynam agarwood. However, there are few comprehensive comparisons between GKA and normal agarwood in terms of traits, global composition, and activity, and some key issues for GKA to be adopted into the traditional Chinese medical (TCM) system have not been elaborated. The two types of agarwood samples were evaluated in terms of trait characteristics, physicochemical indicators, key component groups, and global compositional profile. Furthermore, a molecular docking was performed to investigate the active ingredients. In vitro activity assays were performed to evaluate the activation of adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) by GKA and normal agarwood. The results revealed that, overall, the traits, microscopic characteristics, chemical composition types, and bioactivity between GKA and normal agarwood were similar. The main differences were the content of resin (ethanolic extract content), the content of key component groups, and the composition of the different parent structural groups of 2-(2-phenethyl) chromones (PECs). The contents of total PEC and ethanol extract content of GKA were significantly higher than those of normal agarwood. The MS-based high-throughput analysis revealed that GKA has higher concentrations of sesquiterpenes and flindersia-type 2-(2-phenylethyl) chromones (FTPECs) (m/z 250-312) than normal agarwood. Molecular docking revealed that parent structural groups of FTPECs activated multiple signaling pathways, including the AMPK pathway, suggesting that FTPECs are major active components in GKA. The aim of this paper is to describe the intrinsic reasons for GKA as a high-quality agarwood and a potential source for novel drug development. We combined high-throughput mass spectrometry and multivariate statistical analysis to infer the different components of the two types of agarwood. Then we combined virtual screening and in vitro activity to construct a component/pharmacodynamic relationship to explore the causes of the activity differences between agarwood with different levels of quality and to identify potentially valuable lead compounds. This strategy can also be used for the comprehensive study of other TCMs with different qualities.

Sakuranetin and its therapeutic potentials - a comprehensive review

Sakuranetin (SKN), a naturally derived 7-O-methylated flavonoid, was first identified in the bark of the cherry tree (Prunus spp.) as an aglycone of sakuranin and then purified from the bark of Prunus puddum. It was later reported in many other plants including Artemisia campestris, Boesenbergia pandurata, Baccharis spp., Betula spp., Juglans spp., and Rhus spp. In plants, it functions as a phytoalexin synthesized from its precursor naringenin and is the only known phenolic phytoalexin in rice, which is released in response to different abiotic and biotic stresses such as UV-irradiation, jasmonic acid, cupric chloride, L-methionine, and the phytotoxin coronatine. Till date, SKN has been widely reported for its diverse pharmacological benefits including antioxidant, anti-inflammatory, antimycobacterial, antiviral, antifungal, antileishmanial, antitrypanosomal, glucose uptake stimulation, neuroprotective, antimelanogenic, and antitumor properties. Its pharmacokinetics and toxicological properties have been poorly understood, thus warranting further evaluation together with exploring other pharmacological properties such as antidiabetic, neuroprotective, and antinociceptive effects. Besides, in vivo studies or clinical investigations can be done for proving its effects as antioxidant and anti-inflammatory, antimelanogenic, and antitumor agent. This review summarizes all the reported investigations with SKN for its health-beneficial roles and can be used as a guideline for future studies.

Chemical and Bioactivity Diversity of 2-(2-Phenylethyl)chromones in Agarwood: A Review

2-(2-Phenylethyl)chromone derivatives are regarded as key components in agarwood. An oxygen-containing heterocycle with a benzoannelated γ-pyrone moiety form the bioactive core of 2-(2-phenylethyl)chromones. With different substituents and positions, 2-(2-phenylethyl)chromone derivatives exhibit diverse biological properties, such as antioxidant, antimicrobial, neuroprotective, anti-inflammatory, and acetylcholinesterase inhibitory activities. In this review, we summarized the studies (from January 1976 to September 2021) on phytochemistry, bioactivity and quality control of 2-(2-phenylethyl)chromones. These studies aimed to clarify the chemical specificity, diversity and structure-activity relationship of 2-(2-phenylethyl)chromones. In addition, we assumed that diverse factors such as tree species, induction methods and formation time contribute to the chemical diversity of 2-(2-phenylethyl)chromones. Furthermore, this review contends that different types of 2-(2-phenylethyl)chromones should be utilized in the quality control methods of agarwood.

The structure characteristics, biosynthesis and health benefits of naturally occurring rare flavonoids

Rare flavonoids, a special subclass of naturally occurring flavonoids with diverse structures including pterocarpans, aurones, neoflavonoids, homoisoflavones, diphenylpropanes, rotenoids and 2-phenylethyl-chromones. They are mainly found in legumes with numerous health benefits. Rare flavonoids are regarded as minor flavonoids due to their very limited abundance in nature. This review gives an overview of the natural occurrences of rare flavonoids from previous literatures. Recent findings on the biosynthesis of rare flavonoids have been updated by describing their structural characteristics and classifications. Recent findings on the health benefits of rare flavonoids have also been compiled and discussed. Natural rare flavonoids with various characteristics from different subclasses from plant-based food sources are stated. They show a wide range of health benefits, including antibacterial, anticancer, anti-osteoporosis and antiviral activities. Studies reviewed suggest that rare flavonoids possessing different skeletons demonstrate different characteristic bioactivities by discussing their mechanism of actions and structure-activity relationships. Besides, recent advances on the biosynthesis of rare flavonoids, such as pterocarpans, rotenoids and aurones are well-known, while the biosynthesis of other subclasses remain unknown. The perspectives and further applications of rare flavonoids using metabolic engineering strategies also be expected.

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.

Flavonoids as inhibitors of human neutrophil elastase

Elastase is a proteolytic enzyme belonging to the family of hydrolases produced by human neutrophils, monocytes, macrophages, and endothelial cells. Human neutrophil elastase is known to play multiple roles in the human body, but an increase in its activity may cause a variety of diseases. Elastase inhibitors may prevent the development of psoriasis, chronic kidney disease, respiratory disorders (including COVID-19), immune disorders, and even cancers. Among polyphenolic compounds, some flavonoids and their derivatives, which are mostly found in herbal plants, have been revealed to influence elastase release and its action on human cells. This review focuses on elastase inhibitors that have been discovered from natural sources and are biochemically characterised as flavonoids. The inhibitory activity on elastase is a characteristic of flavonoid aglycones and their glycoside and methylated, acetylated and hydroxylated derivatives. The presented analysis of structure-activity relationship (SAR) enables the determination of the chemical groups responsible for evoking an inhibitory effect on elastase. Further study especially of the in vivo efficacy and safety of the described natural compounds is of interest in order to gain better understanding of their health-promoting potential.

Natural products in agarwood and Aquilaria plants: chemistry, biological activities and biosynthesis

Covering: Up to the end of 2019.Agarwood is a resinous portion of Aquilaria trees, which is formed in response to environmental stress factors such as physical injury or microbial attack. It is very sought-after among the natural incenses, as well as for its medicinal properties in traditional Chinese and Ayurvedic medicine. Interestingly, the chemical constituents of agarwood and healthy Aquilaria trees are quite different. Sesquiterpenes and 2-(2-phenethyl)chromones with diverse scaffolds commonly accumulate in agarwood. Similar structures have rarely been reported from the original trees that mainly contain flavonoids, benzophenones, xanthones, lignans, simple phenolic compounds, megastigmanes, diterpenoids, triterpenoids, steroids, alkaloids, etc. This review summarizes the chemical constituents and biological activities both in agarwood and Aquilaria trees, and their biosynthesis is discussed in order to give a comprehensive overview of the research progress on agarwood.

Metabolite Profiling of Aquilaria malaccensis Leaf Extract Using Liquid Chromatography-Q-TOF-Mass Spectrometry and Investigation of Its Potential Antilipoxygenase Activity In-Vitro

The Aquilaria malaccensis species of the genus Aquilaria is an abundant source of agarwood resin and many bioactive phytochemicals. Recent data regarding the chemical constituents and biological activities of Aquilaria leaves led us to attempt to qualitatively profile the metabolites of Aquilaria malaccensis leaves from a healthy, noninoculated tree through phytochemical screening, GC-MS, and LC/Q-TOF-MS. The present work is also the first to report the antilipoxygenase activity of A. malaccensis leaves from healthy noninoculated tree and investigate its toxicity on oral mucosal cells. A total of 53 compounds were tentatively identified in the extract, some of which have been described in literature as exhibiting anti-inflammatory activity. A number of compounds were identified for the first time in the extract of A. malaccensis leaf, including quercetin, quercetin-O-hexoside, kaempferol-O-dirhamnoside, isorhamnetin-O-hexoside, syringetin-O-hexoside, myricetin, tetrahydroxyflavanone, hesperetin, sissotrin, and lupeol. The antilipoxygenase assay was used to determine the lipoxygenase (LOX) inhibitory potential of the extract, while a WST-1 assay was conducted to investigate the effect of the extract on oral epithelial cells (OEC). The extract implied moderate anti-LOX activity with IC50 value of 71.6 µg/mL. Meanwhile, the cell viability of OEC ranged between 92.55% (10 µg/mL)–76.06% ± (100 µg/mL) upon treatment, indicating some potential toxicity risks. The results attained encourage future studies of the isolation of bioactive compounds from Aquilaria malaccensis leaves, as well as further investigation on the anti-inflammatory mechanisms and toxicity associated with their use.

Acute and Subchronic Oral Toxicity of Fermented Green Tea with Aquilariae Lignum in Rodents

Green tea is generally considered safe, but there have been concerns regarding side effects relating to the main component, catechins, especially hepatotoxicities. We have previously shown beneficial effects of fermented green tea with Aquilariae Lignum (fGT) via an oral route in diabetic and obese models. Thus, the toxicological safety of fGT was assessed at limited oral doses for a rodent. Mice or rats of both genders were orally administered distilled water as a control and fGT at 2.0, 1.0, and 0.5 g/kg. There were no mortalities or gross abnormalities in the fGT groups for 2 weeks following the single oral dose in mice. No fGT-relevant abnormalities were found in postmortem and histopathological examinations, suggesting LD₅₀ of fGT at more than 2.0 g/kg with no specific target organs. There were also no fGT-relevant mortalities or abnormal signs in the repeated oral dose for 13 weeks in rats. In the fGT groups, no body weight changes or daily metabolic changes were found, and hematological and serum biochemical ranges were normal. The postmortem and histopathological examinations revealed few fGT-related abnormalities in most of the organs including the liver, although slight lymphoid cell hyperplasia in the lymph node was observed in a few rats with fGT at 2.0 g/kg. This may be secondary to increased immune response to the highest dose because there were no histopathological lesions or organ weight changes. It suggests nontoxic safety of fGT at up to 2.0 g/kg, which provides useful information for clinical use.

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.

Agarwood Induction: Current Developments and Future Perspectives

Agarwood is a resinous part of the non-timber Aquilaria tree, which is a highly valuable product for medicine and fragrance purposes. To protect the endangered Aquilaria species, mass plantation of Aquilaria trees has become a sustainable way in Asian countries to obtain the highly valuable agarwood. As only physiologically triggered Aquilaria tree can produce agarwood, effective induction methods are long sought in the agarwood industry. In this paper, we attempt to provide an overview for the past efforts toward the understanding of agarwood formation, the evolvement of induction methods and their further development prospects by integrating it with high-throughput omics approaches.

Pilloin, A Flavonoid Isolated from Aquilaria sinensis, Exhibits Anti-Inflammatory Activity In Vitro and In Vivo

Flavonoids, widely present in medicinal plants and fruits, are known to exhibit multiple pharmacological activities. In this study, we isolated a flavonoid compound, pilloin, from Aquilaria sinensis and investigated its anti-inflammatory activity in bacterial lipopolysaccharide-induced RAW 264.7 macrophages and septic mice. Pilloin inhibited NF-κB activation and reduced the phosphorylation of IκB in LPS-stimulated macrophages. Moreover, pilloin significantly suppressed the production of pro-inflammatory molecules, such as TNF-α, IL-6, COX-2 and iNOS, in LPS-treated RAW 264.7 macrophages. Additionally, pilloin suppressed LPS-induced morphological alterations, phagocytic activity and ROS elevation in RAW 264.7 macrophages. The mitogen-activated protein kinase-mediated signalling pathways (including JNK, ERK, p38) were also inhibited by pilloin. Furthermore, pilloin reduced serum levels of TNF-α (from 123.3 ± 7 to 46.6 ± 5.4 ng/mL) and IL-6 levels (from 1.4 ± 0.1 to 0.7 ± 0.1 ng/mL) in multiple organs of LPS-induced septic mice (liver: from 71.8 ± 3.2 to 36.7 ± 4.3; lung: from 118.6 ± 10.6 to 75.8 ± 11.9; spleen: from 185.9 ± 23.4 to 109.6 ± 18.4; kidney: from 160.3 ± 11.8 to 75 ± 10.8 pg/mL). In summary, our results demonstrate the anti-inflammatory potential of pilloin and reveal its underlying molecular mechanism of action.

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.

2-(2-Phenylethyl)-4H-chromen-4-one Derivatives from the Resinous Wood of Aquilaria sinensis with Anti-Inflammatory Effects in LPS-Induced Macrophages

The resinous wood of Aquilaria sinensis, known as agarwood (Chen Xiang in Chinese), is traditionally used for the treatment of abdominal pain, vomiting, circulatory disorders, and dyspnea. Four new 2-(2-phenylethyl)-4H-chromen-4-one derivatives, namely 7-methoxy-2-[2-(4′-hydroxy-phenyl)ethyl]chromone (1), 7-hydroxy-2-[2-(4′-methoxyphenyl)ethyl]chromone (2), 5,6-dihydroxy- 2-[2-(3′-hydroxy-4′-methoxyphenyl)ethyl]chromone (3), and 6-hydroxy-5-methoxy-2-(2-phenyl-ethyl)chromone (4), have been isolated from the resinous wood of A. sinensis, together with nine known compounds. The structures of these compounds were determined through spectroscopic and MS analyses. Among the isolated compounds, neopetasan, 7-methoxy-2-(2-phenylethyl)-chromone, 6,7-dimethoxy-2-(2-phenylethyl)chromone, and 6,7-dimethoxy-2-[2-(4′-methoxy-phenyl)ethyl]chromone inhibited NF-κB activation in LPS-stimulated RAW 264.7 macrophages with relative luciferase activity values of 0.55 ± 0.09, 0.54 ± 0.03, 0.31 ± 0.05, and 0.38 ± 0.14, respectively, versus that of vehicle control (1.03 ± 0.02). In addition, 5,6-dihydroxy-2-[2-(3′-hydroxy-4′-methoxyphenyl)ethyl]chromone, 7-methoxy-2-(2-phenylethyl)chromone, 7-dimethoxy-2-(2-phenylethyl)chromone, and 6,7-dimethoxy-2-[2-(4′-methoxyphenyl)ethyl]chromone could suppress LPS-induced NO production in RAW 264.7 cells and did not induce cytotoxicity against RAW 264.7 cells after 24-h treatment.

The ethanol extract of Aquilariae Lignum ameliorates hippocampal oxidative stress in a repeated restraint stress mouse model

Background

Chronic stress contributes to the development of brain disorders, such as neurodegenerative and psychiatric diseases. Oxidative damage is well known as a causative factor for pathogenic process in brain tissues. The aim of this study is to evaluate the neuroprotective effect of a 30% ethanol extract of Aquilariae Lignum (ALE) in repeated stress-induced hippocampal oxidative injury.

Methods

Fifty BALB/c male mice (12 weeks old) were randomly divided into five groups (n = 10). For 11 consecutive days, each group was orally administered with distilled water, ALE (20 or 80 mg/kg) or N-acetylcysteine (NAC; 100 mg/kg), and then all mice (except unstressed group) were subjected to restraint stress for 6 h. On the final day, brain tissues and sera were isolated, and stress hormones and hippocampal oxidative alterations were examined. We also treated lipopolysaccharide (LPS, 1 μg/mL)-stimulated BV2 microglial cells with ALE (1 and 5 μg/mL) or NAC (10 μM) to investigate the pharmacological mechanism.

Results

Restraint stress considerably increased the serum levels of corticosterone and adrenaline and the hippocampal levels of reactive oxygen species (ROS), nitric oxide (NO), and malondialdehyde (MDA). ALE administration significantly attenuated the above abnormalities. ALE also significantly normalized the stress-induced activation of astrocytes and microglial cells in the hippocampus as well as the elevation of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β). The in vitro assay outcome supplemented ALE could dramatically block NF-κB activation in microglia. The anti-oxidative stress effects of ALE were supported by the results of antioxidant components, 4-hydroxynonenal (4-HNE), NADPH oxidase 2 (NOX2), inducible nitric oxide synthase (iNOS) and NFE2L2 (Nrf2) in the hippocampal tissues.

Conclusions

We firstly demonstrated the neuroprotective potentials of A. Lignum against hippocampal oxidative injury in repeated restraint stress. The corresponding mechanisms might involve modulations in the release of ROS, pro-inflammatory cytokines and stress hormones.

New 2-(2-Phenylethyl)chromone Derivatives and Inhibitors of Phosphodiesterase (PDE) 3A from Agarwood

The MeOH extract of agarwood showed inhibitory activity against phosphodiesterase (PDE) 3A. Fractionation of the extract led to the isolation of two new 2-(2-phenylethyl)chromones, 6,8-dihydroxy-2-[2-(4′-methoxyphenyl)ethyl]chromone (6), and 6,7-dihydroxy-2-(2-phenylethyl)chromone (8), together with six known compounds. All isolated compounds were tested for their PDE 3A inhibitory activity using fluorescence polarization method. Compound 7 showed PDE 3 A inhibitory activity with IC50 of 4.83 μM.