Thermal Degradation Kinetics and pH-Rate Profiles of Iriflophenone 3,5-C-ß-d-diglucoside, Iriflophenone 3-C-ß-d-Glucoside and Mangiferin in Aquilaria crassna Leaf Extract.

The health benefits of the Aquilaria crassna Pierre ex Lecomte leaf extract (AE) make it very useful as an ingredient in food and pharmaceutical products. Iriflophenone 3,5-C-ß-d-diglucoside (1), iriflophenone 3-C-ß-d-glucoside (2) and mangiferin (3) are bioactive compounds of AE. We assessed the stability of AE by investigating the thermal degradation kinetics and shelf-life (t90%) of compounds 1, 2 and 3 using Arrhenius plot models and studied their pH-rate profiles. The results demonstrate that 1 and 2 were degraded, following a first-order kinetic reaction. The degradation of 3 followed first-order reaction kinetics when present in a solution and second-order reaction kinetics in the dried powder form of the extract. According to the first-order kinetic model, the predicted shelf-life (t90%) of the extract at 25 °C in dried form for compound 1 was 989 days with activation energy 129.86 kJ·mol-1, and for 2 it was 248 days with activation energy 110.57 kJ·mol-1, while in the extract solution, the predicted shelf-life of compounds 1-3 was 189, 13 and 75 days with activation energies 86.83, 51.49 and 65.28 kJ·mol-1, respectively. In addition, the pH-rate profiles of 1-3 indicated that they were stable in neutral to acidic environments.

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.

Characterization and Analysis of 2-(2-Phenylethyl)-chromone Derivatives from Agarwood (Aquilaria crassna) by Artificial Holing for Different Times.

A total of fifty-six chromones, including seven 5,6,7,8-tetrahydro-2-(2-phenylethyl)-chromones (THPECs), five 5,6-epoxy-2-(2-phenylethyl)chromones (EPECs), seven 5,6:7,8-diepoxy-2-(2-phenylethyl)chromones (DEPECs) and thirty-seven 2-(2-phenylethyl)chromones of the flidersia type (FTPECs), were characterized by HPLC/DAD/ESI/MS/MS in three agarwood samples (from Aquilaria crassna) induced by artificial holing with different holing times. The characteristic fragmentation behavior of DEPECs and EPECs, and the methods to distinguish these four types of chromones by MS analysis were described for the first time. In addition, it was found that the relative contents of DEPECs and EPECs were down-regulated, while the relative contents of THPECs and FTPECs were up-regulated for the samples from two, four and five years of the agarwood formation time. However, the relative contents of six most widespread and abundant FTPECs presented roughly upward based on the formation time. These results could be referenced to distinguish different agarwood samples collected from different formation time.

Datasets of chemical compounds in three different species of aquilaria using GC-MS coupled with GC-FID analysis.

Aquilaria oil, specifically agarwood oil, is esteemed for its unique fragrance and potential therapeutic qualities, primarily attributed to the presence of significant chemical compounds. These compounds play a vital role in shaping the quality and attributes of Aquilaria oil. The distinct aroma, characterized by intricate, woody, and multifaceted notes, originates directly from specific sesquiterpenes, with notable contributors like agarospirol defining this aromatic profile. The richness and complexity of the oil's scent are closely linked to the concentration and variety of noteworthy compounds within it. Oils containing a diverse range of sesquiterpenes are often considered superior, providing a more refined olfactory experience. This dataset presents a statistical analysis of the chemical compounds present in agarwood oil obtained through the hydrodistillation method from three distinct Aquilaria (A.) species: A. crassna, A. malaccensis, and A. subintegra. The analysis of these chemical compounds utilized Gas Chromatography-Mass Spectrometer (GC-MS) coupled with Gas Chromatography - Flame Ionization Detector (GC-FID). This study's data is crucial for highlighting compounds that contribute to the significance of agarwood oil as a valuable and versatile natural resource. This significance is emphasized by the oil's diverse applications and distinctive chemical composition.

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.

Analytical Methods and Bioassays for Cytotoxicity and Antidiabetic Properties of Aquilaria crassna Leaf Extracts in HepG2 Cells.

Aquilaria crassna is a herbal plant that has recently been reported to possess several biological activities. A. crassna leaf extracts have been demonstrated to have a glucose-lowering effect in animal models. However, it is unclear what phytochemical compounds mediate this antidiabetic property. Here, we describe analytical methods for identifying such compounds from dried leaves by differential extractions with ethanol, butanol, ethyl acetate, and water, respectively. The phytochemical compounds in each fraction were further identified by gas chromatography-mass spectrometry. The cytotoxicity of these fractions was tested against a HepG2 cell line, while the rate of glucose utilization was determined using glucose oxidase assay. Lastly, the inhibitory effect on suppression of hepatic glucose production in HepG2 cells was determined by quantitative real-time PCR of genes encoding pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1,6-bisphosphatase, glucose-6-phosphatase, and liver glycogen synthase.

Study of Aquilaria crassna Wood as an Antifungal Additive to Improve the Properties of Natural Rubber as Air-Dried Sheets.

Fungal growth on rubber sheets confers inferior properties and an unpleasant odor to raw natural rubber (NR) and products made from it, and it causes environmental concerns. The purpose of the present work was to investigate the effects of Aquilaria crassna wood (ACW) on the antifungal, physical and mechanical properties of NR as air-dried sheets (ADS) and ADS filled with ACW. The results show that the ACW-filled ADS had an increased Mooney viscosity, initial plasticity (PO), and high thermo-oxidation plasticity (i.e., high plasticity retention index PRI). Additionally, superior green strength was observed for the ACW-filled ADS over the ADS without additive because of chemical interactions between lignin and proteins in NR molecules eliciting greater gel formation. A significant inhibition of fungal growth on the NR products during storage over a long period (5 months) was observed for ACW-filled ADS. Thus, it can be concluded that ACW could be applied as an antifungal additive that reduces fungal growth. This is a practically important aspect for the rubber industry, as fungal growth tends to spoil and cause the loss of NR sheets during storage. Moreover, the ACW is active as an incense agent, reducing negative impacts from odors that fungi, on rubber surfaces, release. Therefore, these filled intermediate NR products provide added value through, an environmentally friendly approach, this is pleasant to customers.

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.

Extract of Aquilaria crassna leaves and mangiferin are vasodilators while showing no cytotoxicity.

The leaves of Aquilaria spp. promote "physiological balance", and are "cardiotonic and provide blood nourishment". In Asia, these leaves are increasingly consumed as tea and claimed to provide benefits to cardiovascular function, albeit without any scientific proof. Therefore, this study sought to evaluate the action of Aquilaria crassna leaf aqueous extract (AE) on vascular function and vascular smooth muscle cytotoxicity. AE and a main constituent, mangiferin were investigated for their vasorelaxation of rat mesenteric arteries and aortae in vitro. Acute cytotoxicity of AE (0.1-1000 µg/ml) and mangiferin (0.1-100 µM) on rat enzymatically isolated vascular smooth muscle cells was assayed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide. AE dilated rat mesenteric arteries (EC50∼107 µg/ml, Emax∼95%) more than aorta (EC50∼265 µg/ml, Emax∼76%, p < 0.05). AE-induced vasodilation in mesenteric artery was reduced by endothelial removal (EC50∼202 µg/ml, p < 0.05), incubation with endothelial nitric oxide synthase (eNOS) (100 µM, L-NAME) (EC50∼309 µg/ml, p < 0.05), and partly reduced by L-type Ca2+ channel blockade at higher concentrations. Likewise, mangiferin (1-100 µM) dilated the mesenteric artery more potently than the aorta. However, its maximum relaxation was less than with AE (41% in the mesenteric artery and <10% in the aorta). Isolated vascular smooth muscle cells incubated in AE or mangiferin for 1 h showed no cytotoxicity. Thus, AE is a vasorelaxant while being free of acute cytotoxicity towards vascular smooth muscle, thus potentially ameliorating human vascular dysfunction.

Dimeric 2-(2-phenylethyl)chromones from the agarwood of Aquilaria crassna in Laos.

Four new dimeric 2-(2-phenylethyl)chromones (1-4) were isolated from the agarwood of Aquilaria crassna in Laos. All structures were determined based on extensive spectroscopic methods including IR, UV, 1D and 2D NMR, ECD, and HRMS. The structures of compounds 1-3 were characterized by two C-O-C linkages between the two chromone moieties, while compound 4 featured one C-O-C linkage and one CC bond connecting with two chromone moieties. Compounds 1 and 3 showed weak cytotoxicity against human hepatocellular carcinoma BEL-7402 cell line with IC50 values of 44.68 and 42.10 µΜ.

LC-MS guided identification of dimeric 2-(2-phenylethyl)chromones and sesquiterpene-2-(2-phenylethyl)chromone conjugates from agarwood of Aquilaria crassna and their cytotoxicity.

Four previously unreported dimeric 2-(2-phenylethyl)chromones (1-4a) and three unprecedented sesquiterpene-2-(2-phenylethyl)chromone conjugates (5-7), comprising a sesquiterpenoid and a 5,6,7,8-tetrahydroxy-2-(2-phenylethyl)-5,6,7,8 -tetrahydro-4H-chromone moiety, as well as three known dimeric 2-(2-phenylethyl)chromones (4b, 8a, 8b) were identified from agarwood originating from Aquilaria crassna in Cambodia by LC-MS guided separation. Their structures were elucidated by extensive NMR techniques, HRESIMS and CD. All compounds were evaluated for their cytotoxicity against four human cancer cell lines. Compounds 6, 7, 8a, 8b displayed a range of cytotoxic activities with IC50 values in the rang 10.93-49.0 µM.

Dimeric sesquiterpenoid-4H-chromone derivatives from agarwood of Aquilaria crassna and their cytotoxicity.

Six previously undescribed uncommon ester-bonded dimeric compounds (aquilacrassnins A-F) containing a sesquiterpenoid and a 5,6,7,8-tetrahydroxy-2-(2-phenylethyl)-5,6,7,8-tetrahydro -4H-chromone units were isolated from the EtOAc extract of agarwood originating from Aquilaria crassna. Their structures were elucidated by spectroscopic (NMR, UV, IR, MS, and ECD) methods. All the compounds were tested for AChE inhibitory activity and cytotoxicity against K562, BEL-7402, SGC-7901, Hela, and A549 tumor cell lines. The results showed that aquilacrassnin A, B, and E exhibited weak cytotoxicity against the five tested cell lines, whereas all the compounds were inactive against AChE.

Four new bi-2-(2-phenylethyl)chromone derivatives of agarwood from Aquilaria crassna.

Four new bi-2-(2-phenylethyl)chromone derivatives, crassins A-D (1-4), were isolated from the EtOAc extract of agarwood originating from Aquilaria crassna. The structures including the absolute configurations of compounds were unambiguously elucidated by extensive spectroscopic methods (1D and 2D NMR, UV, ECD, IR, MS), and by comparison with the literature. The isolated compounds were tested for their acetylcholinesterase (AChE) and α-glucosidase inhibitory activities, as well as cytotoxic activities. All the compounds showed weak inhibitory activity against AChE, while compounds 3 and 4 also displayed weak cytotoxicity against human myeloid leukemia cell line (K562).

Three new sesquiterpenoids from agarwood of Aquilaria crassna.

Three new sesquiterpenoids (1-3), together with two known ones were isolated from the EtOAc extract of agarwood originating from Aquilaria crassna. The new compounds were elucidated on the basis of spectroscopic techniques (UV, IR, MS, 1D and 2D NMR). Compounds 1-5 were isolated from agarwood of A. crassna for the first time. In the acetylcholinesterase inhibition experiment of 2-5, compound 3 showed acetylcholinesterase inhibition activity (IR 42.9±0.6%). Compound 5 expressed antibacterial activities against Staphylococcus aureus and Ralstonia solanacearum with diameter of the inhibition zones of 12.35±0.11mm and 16.90±0.09mm, respectively.

Characterization of α-humulene synthases responsible for the production of sesquiterpenes induced by methyl jasmonate in Aquilaria cell culture.

The resinous portions of Aquilaria and Gyrinops plants are known as 'agarwood' and have a distinctive fragrance. To examine the biosynthesis of these fragrant compounds, we previously established cell cultures of Aquilaria crassna in which the production of three sesquiterpenes (α-guaiene, α-humulene, and δ-guaiene) could be induced by methyl jasmonate (MJ), and showed that cloned δ-guaiene synthase from MJ-treated cells is involved in the synthesis of these three compounds, although only very small amounts of α-humulene are produced. In the present study, cDNAs encoding α-humulene synthases were also isolated. Three putative sesquiterpene synthase clones (AcHS1-3) isolated from the MJ-treated cells had very similar amino acid sequences and shared 52 % identity with δ-guaiene synthases. The recombinant enzymes catalyzed the formation of α-humulene as a major product. Expression of transcripts of the α-humulene synthase and δ-guaiene synthase genes in cultured cells increased after treatment with MJ. These results revealed that these α-humulene and δ-guaiene synthases are involved in the synthesis of three sesquiterpenes induced by MJ treatment.

Antipyretic, analgesic and anti-oxidative activities of Aquilaria crassna leaves extract in rodents.

In Thailand, the leaves of Aquilaria crassna have been used traditionally for the treatments of various disorders, but without any scientific analysis. In this study, the antipyretic, analgesic, anti-inflammatory and anti-oxidative properties of A. crassna leaves extract were investigated at a wide dose range in rodents. Experimental animals were treated orally with an aqueous extract of Aquilaria crassna leaves (ACE). They were tested for antipyretic (Baker's yeast-induced fever in rats), analgesic (hot plate test in mice) and anti-inflammatory (carrageenan-induced paw edema in rats) activities. An anti-oxidative effect of ACE was evaluated by using the DPPH anti-oxidant assay. The results showed that, after 5 hours of yeast injection, 400 and 800 mg/kg ACE significantly reduced the rectal temperature of rats. Mice were found significantly less sensitive to heat at an oral dose of 800 mg/kg ACE, after 60 and 90 min. No anti-inflammatory activity of ACE at an 800 mg/kg dose could be observed in the rat paw assay. An anti-oxidative activity of ACE was observed with an IC (50)value of 47.18 µg/ ml. No behavioral or movement change could be observed in mice after oral administration of ACE (800 or 8,000 mg/kg) for seven consecutive days. Interestingly, from the second day of treatment, animals had a significant lower body weight at the 8,000 mg/kg dose of ACE compared to the control. No toxicity was identified and the results of this study state clearly that Aquilaria crassna leaves extracts possess antipyretic, analgesic and anti-oxidative properties without anti-inflammatory activity.