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  • Kobe0065 australia L Family Leguminosae widely distributed i

    2022-05-13

    L. (Family Leguminosae) widely distributed in tropical and subtropical regions of the world. As a medicinal and edible plant, it is widely used in Asia, especially in China, Korea, Japan and India. It was first recorded in Shen Nong Ben Cao Jing (神农本草经), and was described having the effect of clearing heat and improving vision, moistening the intestines to relieving constipation. Modern pharmacological studies have shown that could relieve constipation, improve vision and exhibit effects such as antihypertensive, hypolipidemic, hepatoprotective, antioxidant and bacteriostatic., , , , The main chemical constituents of are anthraquinone, naphthalene and naphthalopyranone. In addition, it also contains flavonoids, sterols and polysaccharides., , Among them, anthraquinones, naphthalene and naphthopyran ketones are the main active ingredients for hepatoprotective, hypolipidemic and antimicrobial activities., , , Anthraquinones also have antioxidant effects,, while naphthalene and naphthopyran ketones have hypoglycemic effects. In order to find more active components in , we separated the small polar components (petroleum ether fraction) of , and obtained two new anthraquinone aglycones together with thirteen known compounds., , Type II diabetes is a syndrome characterized by relative insulin deficiency, insulin resistance and increased hepatic Kobe0065 australia output. One of the treatments for type II diabetes is to reduce postprandial blood sugar levels by inhibiting the activities of α-glucosidase., There are many synthetic α-glucosidase inhibitors on the market, such as Voglibose, Acarbose, Miglitol., However, it has also been reported that synthetic inhibitors may cause many side effect., Some natural -glucosidase inhibitors show low toxicity and side effects, and have certain potential for development. Many scholars have found ingredients that can inhibit the activities of -glucosidase from edible or medicinal plants. , It has been reported that has hypoglycemic effect, therefore, the inhibitory activity of -glucosidase of the constituents isolated from has been determined. The emergence and development of many diseases are closely related to the overproduction of reactive oxygen species (ROS) in human body, such as aging, cancer, Alzheimer’s disease, inflammation, as well as cardiovascular diseases., , Antioxidants can eliminate endogenous ROS produced by the aerobic metabolism of the human body, block damage caused by excessive free radicals to human cell membranes and macromolecules such as proteins and DNA. It is particularly important to find natural antioxidants with lower toxicity than synthetic antioxidants. So, we tested the antioxidant activities of these compounds isolated from by DPPH assay. The small polar parts of were extracted with petroleum ether. And this fraction was separated via column chromatography using organic solvents to obtain two new compounds, 8-hydroxy-1,2,6,7-tetramethoxy-3-methylanthraquinone () and 1,6,8-trihydroxy-2,7-dimethoxy-3-methylanthraquinone (), together with thirteen known compounds (), including ten anthraquinone aglycones, 7-methoxy obtusifolin (), chrysophanol (), physicon (), obtusifolin , chrysophanol 8-methyl ether (), obtusin (), chryso-obtusin (), aurantio-obtusin (), questin (), 2-acetyl physcion (); two naphthopyrone aglycones, rubrofusarin (),, toralactone (); one dianthrone aglycone, crisofanol-10,10′-biantrona () (). Their chemical structures were elucidated by H and C NMR, HMBC, HSQC and HR-ESI-MS data and by comparisons with previously reported data. Compound was isolated as a yellow powder (acetone), and its molecular formula was determined to be CHO by HR-ESI-MS (/ 359.1121 [M+H], calcd. for 359.1131). The H NMR spectrum of contained one hydroxy proton signal at 13.14 (1H, s), two aromatic proton signals at 7.94 (1H, s), 7.40 (1H, s), and five proton signals at 4.03 (3H, s), 4.02 (3H, s), 3.99(3H, s), 3.97(3H, s), 2.40(3H, s) were assigned to four methoxy and one methyl proton. The C NMR spectrum displayed 19 carbon signals, corresponding to two ketones ( 188.0, 181.6), twelve aromatic carbon atoms (from 103.3 to 158.3), four methoxy groups (from 56.5 to 61.4), and one methyl carbon atom ( 16.8). From the spectral and chromatographic data, it can be preliminarily inferred that the compound may be anthraquinones. Two isolated aromatic hydrogen signals, 7.94 and 7.40, were found to be correlated with the carbonyl signal 181.6 (C-10) by HMBC spectra, indicating that the two hydrogens were H-4 and H-5, respectively. Therefore, compound was identified as 1, 2, 3, 6, 7, 8-hexasubstituted anthraquinones. HMBC correlations between the methyl proton signal ( 2.40) and 158.3, 139.7, 126.3 and long-range correlations between the aromatic hydrogen signal ( 7.94) and 16.8, 158.3, 125.0 suggested a methyl group at C-3 and hydrogen signal ( 7.94) at H-4, so 7.40 at H-5. The location of hydroxyl group at C-8 was confirmed from the HMBC correlations between hydroxy proton signal ( 13.14) and 141.8, 156.8, 113.2 and correlations between H-5 ( 7.40) and 141.8, 113.2. The remaining four methoxy groups are attached to C-1, C-2, C-6 and C-7, respectively. Therefore, the compound is 8-hydroxy-1, 2, 6, 7-tetramethoxy-3-methylanthraquinone, which is a new compound (). According to the correlation spectra of HSQC and HMBC, the H NMR and C NMR signals of compound were assigned ().