Bioactive pterocarpans from the root of Astragalus membranaceus var. mongholicus

Bioactive Phenylpropanoid Glycosides, Dimers, and Heterodimers from the Bark of Cinnamomum cassia (L.) J.Presl

Six new phenylpropanoid glycosides (1-6), two new phenylethanol glycosides (7 and 8), one new phenylmethanol glycoside (9), three new phenylpropanoid dimers (10-12), two new phenylpropanoid-flavan-3-ol heterodimers (13 and 14), and six known relevant compounds (15-20) were isolated and identified from the well-liked edible and medicinal substance (the bark of Cinnamomum cassia (L.) J.Presl). The structures of these isolates were determined by using spectroscopic analyses, chemical methods, and quantum chemical calculations. Notably, compounds 4-9 were rare apiuronyl-containing glycosides, and compounds 13 and 14 were heterodimers of phenylpropanoids and flavan-3-ols linked through C-9″-C-8 bonds. The antioxidant and α-glucosidase inhibitory activities of all isolates were evaluated. Compounds 10 and 12 exhibited DPPH radical scavenging capacities with IC50 values of 20.1 and 13.0 μM, respectively (vitamin C IC50 value of 14.3 μM). In the ORAC experiment, all these compounds exhibited different levels of capacity for scavenging free radicals, and compound 10 displayed extraordinary free radical scavenging capacity with the ORAC value of 6.42 ± 0.01 μM TE/μM (EGCG ORAC value of 1.54 ± 0.02 μM TE/μM). Compound 12 also showed significant α-glucosidase inhibitory activity with an IC50 of 56.3 μM (acarbose IC50 of 519.4 μM).

Progress on metabolites of Astragalus medicinal plants and a new factor affecting their formation: Biotransformation of endophytic fungi

It is generally believed that the main influencing factors of plant metabolism are genetic and environmental factors. However, the transformation and catalysis of metabolic intermediates by endophytic fungi have become a new factor and resource attracting attention in recent years. There are over 2000 precious plant species in the Astragalus genus. In the past decade, at least 303 high-value metabolites have been isolated from the Astragalus medicinal plants, including 124 saponins, 150 flavonoids, two alkaloids, six sterols, and over 20 other types of compounds. These medicinal plants contain abundant endophytic fungi with unique functions, and nearly 600 endophytic fungi with known identity have been detected, but only about 35 strains belonging to 13 genera have been isolated. Among them, at least four strains affiliated to Penicillium roseopurpureum, Alternaria eureka, Neosartorya hiratsukae, and Camarosporium laburnicola have demonstrated the ability to biotransform four saponin compounds from the Astragalus genus, resulting in the production of 66 new compounds, which have significantly enhanced our understanding of the formation of metabolites in plants of the Astragalus genus. They provide a scientific basis for improving the cultivation quality of Astragalus plants through the modification of dominant fungal endophytes or reshaping the endophytic fungal community. Additionally, they open up new avenues for the discovery of specialized, green, efficient, and sustainable biotransformation pathways for complex pharmaceutical intermediates.

Two new meroterpenoids from the bark of Cinnamomum cassia and their antioxidant activity

Two new (1 and 2) meroterpenoids were isolated from the bark of Cinnamomum cassia. Their structures were determined by spectroscopic analyses and chemical methods. Antioxidant activities of 1 and 2 were evaluated by the ORAC and DPPH radical scavenging assays, and the results revealed that compound 2 displayed oxygen radical absorbance capacity. The discovery of compounds 1 and 2 added new members of this kind of natural product.

High-Throughput Phytochemical Unscrambling of Flowers Originating from Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) P. K. Hsiao and Astragalus membranaceus (Fisch.) Bug. by Applying the Intagretive Plant Metabolomics Method Using UHPLC-Q-TOF-MS/MS

Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) P. K. Hsiao (MO) and Astragalus membranaceus (Fisch.) Bug. (ME) are two primary sources of the Astragalus herb, also known as "Huangqi" in China, which is widely applied to treat hypertension, glomerulonephritis, ischemic heart disease, and diabetes mellitus. As two different sources of the Astragalus herb, the chemical profiles of MO and ME may be different. Previous studies showed abundant differences in chemical composition between MO and ME. Therefore, the by-products of MO and ME, such as Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) P. K. Hsiao flower (MOF) and Astragalus membranaceus (Fisch.) Bug. flower (MEF), may have different phytochemical profiles. In this paper, a metabolomics method combined with ultra-high-performance liquid chromatography and electrospray ionization/quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS) was employed to analyze the components of MOF and MEF. Consequently, the results of principal component analysis (PCA) showed that MOF and MEF could be separated clearly. In total, 31 chemical markers differentiating MOF and MEF were successfully identified, including 22 flavonoids, 8 isoflavones and 1 benzopyran. Among them, the contents of 18 components, including Calycosin, Cyanidin-3-O-glucoside, Quercetin, Rutin, Kaempferol, Formononetin, Isomucronulatol and Prim-O-glucosylcimifugin in MEF, were significantly higher than in MOF. In turn, the contents of another 13 components, covering Biochanin A, Tectoridin, Isomucronulatol-7-O-glucoside, Liquiritin, Rhamnetin, etc., were lower in the MEF group than that in the MOF group. It is worth noting that flavonoids, especially flavonoid glycosides, were the primary active chemical ingredients in MOF and MEF. The 18 ingredients in MEF with a higher level carried out diverse activities, like anti-oxidant, anti-inflammatory, anti-bacterial and anti-tumor activities, which led us to speculate that MEF may have greater pharmacological effects and potential development prospects than MOF. The present results displayed that the contents of ingredients in the two different species of plants were radically different, and there was significant uniqueness to the components of MOF and MEF. Our study not only provides helpful chemical information for further quality assessment and active mechanism research of MOF and MEF but also offers scientific support for the resource utilization of MOF and MEF.

Radical Scavenging Capability and Mechanism of Three Isoflavonoids Extracted from Radix Astragali: A Theoretical Study

As a valuable traditional Chinese herbal medicine, Radix Astragali has attracted much attention due to its extensive pharmacological activities. In this study, density functional theory (DFT) was used thermodynamically and kinetically in detail to predict the antioxidant activity and reaction mechanisms involved in the free radical scavenging reactions of three representative isoflavonoids (formononetin, calycosin, and calycosin-7-glucoside) extracted from Radix Astragali. Three main mechanisms, including hydrogen atom transfer (HAT), proton transfer after electron transfer (SET-PT), and sequential proton loss electron transfer (SPLET) were examined by calculating the thermodynamic parameters. It was found that HAT is the predominant mechanism in the gas phase, while SPLET is supported in the solvent environment. The isoflavonoids' order of antioxidant activity was estimated as: calycosin > calycosin-7-glucoside > formononetin. For the calycosin compound, the result revealed the feasibility of double HAT mechanisms, which involve the formation of stable benzodioxazole with significantly reduced energy in the second H⁺/e^- reaction. In addition, the potential energy profiles and kinetic calculations show that the reaction of ^•OH into the 3'-OH site of calycosin has a lower energy barrier (7.2 kcal/mol) and higher rate constant (4.55 × 10⁹ M^-1 s^-1) compared with other reactions in the gas phase.

Spectroscopic analysis, kinetic mechanism, computational docking, and molecular dynamics of active metabolites from the aerial parts of Astragalus membranaceusBunge as tyrosinase inhibitors

A new isoflavane derivative (2), a new natural isoflavane (6), four new oleanane-type triterpenoid saponins (23, 25, 28, and 29), and twenty three known secondary metabolites (1, 3-5, 7-22, 24, 26, and 27) were isolated from the aerial parts of Astragalus membranaceus Bunge. The chemical structures of these compounds were elucidated through spectroscopic analysis and compared with those identified in previous studies. Tyrosinase inhibition ability of isolated compounds (1-29) was evaluated. Of these, compounds 3, 4, 6, and 14 exhibited inhibitory effects, with IC₅₀ values ranging from 24.6 to 59.2 μM. According to kinetic analysis, compounds 3 and 4 were non-competitive inhibitors of tyrosinase, whereas compounds 6 and 14 inhibited tyrosinase in uncompetitive and competitive modes, respectively. Molecular docking analysis identified that compounds 3, 4, and 6 could bind to allosteric sites and compound 14 could bind to the catalytic site of tyrosinase, which is consistent with the results of kinetic studies. Molecular dynamics behaviors of the active compounds in complex with tyrosinase were investigated via 60 ns simulation which demonstrated their high stability. These findings indicate that the aerial parts of A. membranaceus are a potential source of natural tyrosinase inhibitors.

A Review of The Application of Spectroscopy to Flavonoids from Medicine and Food Homology Materials

Medicinal and food homology materials are a group of drugs in herbal medicine that have nutritional value and can be used as functional food, with great potential for development and application. Flavonoids are one of the major groups of components in pharmaceutical and food materials that have been found to possess a variety of biological activities and pharmacological effects. More and more analytical techniques are being used in the study of flavonoid components of medicinal and food homology materials. Compared to traditional analytical methods, spectroscopic analysis has the advantages of being rapid, economical and free of chemical waste. It is therefore widely used for the identification and analysis of herbal components. This paper reviews the application of spectroscopic techniques in the study of flavonoid components in medicinal and food homology materials, including structure determination, content determination, quality identification, interaction studies, and the corresponding chemometrics. This review may provide some reference and assistance for future studies on the flavonoid composition of other medicinal and food homology materials.

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.