Jingya Cao

A chemical study on Chenopodium quinoa Willd. bran identified four new triterpene saponins (1-4) and 12 known analogues (5-16). The structures were determined through extensive spectroscopic analysis. Compounds 1 and 2 were identified as rare dodecandralol triterpenoid saponins, marking their first discovery in C. quinoa. Compounds 1-16 were evaluated for α-glucosidase inhibitory activity, with queretaroic acid 28-O-β-d-glucopyranosyl ester (QA, IC₅₀ = 42.3 ± 4.1 μM) showing potent inhibitory activity in a mixed-type manner. Surface plasmon resonance (SPR) and Fourier transform infrared (FT-IR) assays confirmed QA's strong binding affinity to α-glucosidase. Molecular docking and dynamics simulations revealed QA interacts with the enzyme primarily via hydrogen bonding and hydrophobic contacts, resulting in conformational changes and inhibition activity of α-glucosidase. Additionally, QA strongly suppressed postprandial hyperglycemia in diabetes mellitus (DM) mice in vivo. These findings establish C. quinoa bran as a source of quinoa saponins with potential for hypoglycemic drug development.

Three pairs of novel enantiomeric 8-O-4′ type neolignans (1a/1b–3a/3b), together with seven known analogues (4–10), were isolated from the whole plants of Saussurea medusa. Their structures were elucidated by extensive spectroscopic data analysis and electric circular dichroism (ECD) calculations after chiral separations. All compounds were obtained from S. medusa for the first time, and compounds 1–3 and 5–10 had never been obtained from the genus Saussurea previously. The anti-inflammatory activities of the compounds were evaluated by determining their inhibitory activities on the production of NO and inducible nitric oxide synthase (iNOS) expression in LPS-stimulated RAW 264.7 cells. Compounds (+)-1a, (−)-1b and 5–7 inhibited NO production and had IC₅₀ values ranging from 14.3 ± 1.6 to 41.4 ± 3.1 μM. Compound 7 induced a dose-dependent reduction in the expression of iNOS in LPS-treated RAW 264.7 cells. Molecular docking experiments showed that all active compounds exhibited excellent docking scores (<−7.0 kcal/mol) with iNOS. Therefore, compounds (+)-1a, (−)-1b and 5–7 isolated from the whole plants of S. medusa may have therapeutic potential in inflammatory diseases.

The present study extracted total saponins from quinoa husks with pressurized hot water extraction and optimized the extraction conditions. The response surface methodology (RSM) with a Box–Behnken design (BBD) was employed to investigate the effects of extraction flow rate, extraction temperature and extraction time on the extraction yield of total saponins. A maximal yield of 23.06 mg/g was obtained at conditions of 2 mL/min, 210 °C and 50 min. The constituents of the extracts were analyzed by liquid chromatography–mass spectrometry (LC-MS). A total of twenty-three compounds were identified, including five flavonoids, seventeen triterpenoid saponins and a phenolic acid. Moreover, we performed an in vitro assay for the α-glucosidase activity and found a stronger inhibitory effect of the quinoa husk extracts than acarbose, suggesting its potential to be developed into functional products with hypoglycemic effect. Finally, our molecular docking analyses indicated triterpenoid saponins as the main bioactive components.

Free radicals, including 1,1-diphenyl-2-picrylhydrazyl, mediate oxidative stress to cause many chronic diseases (including cardiovascular diseases, diabetes and cancer). The extract of traditional Tibetan medicine Lepidium latifolium L. (L. latifolium) was reported to have free radical inhibition ability. Therefore, a system method was established to separate the ethanol extract of L. latifolium to prepare two main antioxidant compounds. First of all, silica gel and a medium-pressure liquid chromatography tower were used for pre-treatment of the ethanol extract of L. latifolium to obtain the main antioxidant active component fraction 4 through online high-performance liquid chromatography-1,1-diphenyl-2-picrylhydrazyl (HPLC-DPPH) assay. Then, fraction 4-1 was obtained by one-dimensional preparation using Megres C18 chromatographic column, and two active compounds with IC₅₀ values 59.9 and 71.3 μg/mL were obtained by two-dimensional preparation using Click XIon chromatographic column. Through the study of the chemical components and separation methods of L. latifolium, the combination of HPLC-DPPH assay and two-dimensional preparative liquid chromatography was realized, providing a reference for the separation of active compounds from L. latifolium.