Five 2-(2-Phenylethyl)chromones from Sodium Chloride-Elicited Aquilaria sinensis Cell Suspension Cultures

Salty treatment increased bioactive compounds accumulation during agarwood development in Aquilaria sinensis trees

To compare the bioactive compounds in agarwood induced by different methods in Aquilaria sinensis(Lour.) Gilg trees, a two dimensional thin layer chromatograph(2D-TLC) combined with effect directive analysis(EDA) was developed. Three antioxidants were found by 2D-TLC-DPPH and further identified as 2-(2-phenylethyl) chromones(PECs) with LC-MS/MS. The 3 antioxidants decreased along agarwood formation and their compositions in drilling induced agarwood differed with those in microbe culture induced agarwood. Further study showed NaCl treatment promoted antioxidants accumulation in agarwood induced by drilling or hot drilling. Hot drilling combined with salty stimulation was most efficient in some chemicals accumulation, which were identified as PECs with antioxidant, tyrosinase or β-glucosidase inhibiting activities by 2D-TLC-EDA-LC-MS/MS. This study provided a 2D-TLC-EDA-LC-MS/MS method for bioactive compounds screen and qualification of agarwood. Based on this method, non-conventional methods were found to accelerate the accumulation of some bioactive PECs in A. sinensis trees.

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.

Characteristic quality analysis for biologically induced agarwood columns in Aquilaria sinensis

Current artificial agarwood-inducing techniques yield low quality and quantities of agarwood. On account of unclear agarwood formation mechanism there's still no high-efficiency agarwood inducing method globally spread. In this study, a complete agarwood column was taken out of the live tree trunk at 6 months post-treatment by a novel agarwood-inducing method (Agar-Bit) in cultivated Aquilaria sinensis trees, and was first divided into 8 parts (A1-4, B1-4) involving agarwood layer (A part) and brown inner layer (B part) according to its color and length for analysis. These eight parts were analyzed microscope observation, 6 chromones' contents and characteristic chromatograms by HPLC (high performance liquid chromatography), GC-MS (gas chromatography-mass spectrometer) with to determine chemical changes. Other quality characteristics, TLC (thin-layer chromatography) and alcohol soluble extraction content, were also determined. Our results showed that resin changed with A to B part and microstructure changed with length. Six chromones in the eight parts varied with layers. Result of characteristic chromatograms showed that both A and B parts contained six characteristic peaks. Volatile component distributed mainly in A part, but important chromones were also detected in B parts. Results from TLC and alcohol soluble extraction content also showed that B part contained characteristic compounds of agarwood. In addition, some compounds in the essential oil detected by GC-MS in A part produced by Agar-Bit were similar to that found in natural agarwood, compounds in B parts were similar to BC agarwood, as were the results for the TLC and alcohol soluble extraction content. In conclusion, the chemical distribution obtained here from Agar-Bit could provide some clues to optimize high production and high efficiency stimulating method for whole tree full of resin in Aquilaria sinensis and to reveal the subtle agarwood formation mechanism throughout a whole trunk.

Chromone a Privileged Scaffold in Drug Discovery: Developments on the Synthesis and Bioactivity

Chromones are the class of secondary metabolites broadly occurred in the plant kingdom in a noticeable quantity. This rigid bicyclic system has been categorized "as privileged scaffolds in compounds" in medicinal chemistry. The wide biological responses made them an important moiety in a drug discovery program. This review provides updates on the various methods of synthesis of chromones and biological applications in medicinal chemistry. Various synthetic strategies for the construction of chromones include readily available phenols, salicylic acid and its derivatives, ynones, chalcones, enaminones, chalcones and 2-hydroxyarylalkylketones as starting materials. Synthesis of chromones by using metal, metal free, nanomaterials and different catalysts are included. Details of diverse biological activities such as anti-cancer agents, antimicrobial agents, anti-viral property, anti-inflammatory agents, antioxidants, Monoamine Oxidase-B (MAO-B) Inhibitors, anti-Alzheimer's agents, anti-diabetic agent, antihistaminic potential, antiplatelet agents of chromone derivatives are diecussed.

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.

Anti-inflammatory 5,6,7,8-tetrahydro-2-(2-phenylethyl)chromones from agarwood of Aquilaria sinensis

Four new 5,6,7,8-tetrahydro-2-(2-phenylethyl)chromones, aqulisinone A (1), (5S, 6R,7S,8S)-8-chloro-5,6,7-trihydroxy-2-[2-(4'-methoxyphenylethyl)]-5,6,7,8-tetrahydrochromone (2), (5S,6R,7S,8S)-8-chloro-5,6,7-trihydroxy-2-(2-phenylethyl)-5,6,7,8-tetrahydrochromone (3), (5S*,6R*,7R*,8S*)-8-chloro-5-ethoxy-6,7-dihydroxy-2-[2-(3'-hydroxy-4'-methoxy-phenylethyl)-5,6,7,8-tetrahydrochromone (4), and seven known analogues (5-11) were isolated from agarwood produced of Aquilaria sinensis. Among the new compounds, 4 is an artifact. The structures were elucidated using spectroscopic methods and by comparison with published NMR spectroscopic data. The absolute configurations of 1-3 were defined based on single-crystal X-ray diffraction and electronic circular dichroism (ECD) data. Compound 1 features a (5,5'')-carbon-carbon bond linkage connecting two 2-(2-phenylethyl)chromone monomeric units. All the new compounds were evaluated for their anti-inflammatory activities by inhibiting the lipopolysaccharide (LPS)-induced nitric oxide (NO) release in RAW264.7 cells, 2 with an IC₅₀ value of 3.46 μM.

A full solution for multi-component quantification-oriented quality assessment of herbal medicines, Chinese agarwood as a case

The quality of herbal medicines (HMs) is the prerequisite for their pronounced therapeutic outcomes in clinic, and multi-component (also known as quality markers, Q-markers) quantification has been widely emphasized as a viable means for quality evaluation. Because of the chemical diversity, the quality control practices are extensively dampened by four principal technical bottlenecks, including the lack of authentic compounds, large polarity span, extensive concentration range, and signal misrecognition for those potential Q-markers. An attempt to promote the potential of LC-MS/MS is made herein to cope with those obstacles and Chinese agarwood was employed as a case study. Firstly, a home-made fraction collector was introduced to automatically fragment the entire extract into a panel of fractions-of-interest. Secondly, quantitative ¹H-NMR was deployed to offset the LC-MS/MS potential towards in-depth chemical profiling each fraction, and those well-defined fractions were then pooled and combined with some accessible authentic compounds to generate the pseudo-mixed standard solution. Thirdly, serial improvements were conducted for LC-MS/MS measurements. Reversed phase LC and hydrophilic interaction LC were serially coupled in respond to the large polarity window, and online parameter optimization, response tailoring, as well as RRCEC (relative response vs. collision energy curve) matching were integrated in MS/MS domain to advance the quantitative confidences. Simultaneous determination was conducted for 26 components, in total, in Chinese agarwood after method validation. In particular, authentic compound-free quantification was achieved for eight 2-(2-phenylethyl)chromone derivatives. Above all, the strategy is a promising solution to completely tackle with the technical barriers toward Q-marker quantification-oriented quality control of Chinese agarwood, as well as other HMs.