Preparation and Antioxidant Activities of Phenylethanoids from Dracocephalum heterophyllum

Teucrium montanum L.-Unrecognized Source of Phenylethanoid Glycosides: Green Extraction Approach and Elucidation of Phenolic Compounds via NMR and UHPLC-HR MS/MS

Health-oriented preferences, a demand for innovative food concepts, and technological advances have greatly influenced changes in the food industry and led to remarkable development of the functional food market. Incorporating herbal extracts as a rich source of bioactive compounds (BC) could be an effective solution to meet the high demand of consumers in terms of expanding the high-quality range of functional foods. The aim of this study is the valorization of the bioactive potential of T. montanum L., an understudied Mediterranean plant species, and the in-depth elucidation of a polyphenolic profile with a UHPLC-HR MS/MS and NMR analysis. The total phenolic content (TPC) and antioxidant capacity (AC) were determined on heat-assisted (HAE), microwave-assisted (MAE) and subcritical water (SWE) extracts. In terms of antioxidant capacity, SWE extracts showed the most notable potential (ABTS: 0.402-0.547 mmol eq Trolox g-1 dw, DPPH: 0.336-0.427 mmol eq Trolox g-1 dw). 12 phenolic compounds were identified in the samples of T. montanum from six microlocations in Croatia, including nine phenylethanoid glycosides (PGs) with total yields of 30.36-68.06 mg g-1 dw and 25.88-58.88 mg g-1 dw in HAE and MAE extracts, respectively. Echinacoside, teupolioside, stachysoside A, and poliumoside were the most abundant compounds HAE and MAE extracts, making T. montanum an emerging source of PGs.

Recent Advances in Analysis of Food and Beverages

In this section, we summarize the characteristics of the published papers according to different typologies [...]

Efficient Production of Antioxidants from Rape Pollen via a Chromatographic Strategy

Rape pollen has always been considered as a research hotspot in health foods and pharmaceuticals due to its abundance of natural active ingredients. In this work, a compound with antioxidant activity was directly isolated from the methanol extract of rape pollen using a two-step procedure, under the supervision of online HPLC−1,1-diphenyl-2-picrylhydrazyl (HPLC-DPPH) detection. Firstly, online HPLC−DPPH detection was used to identify the active peaks in the methanol extract of rape pollen, and then the methanol extract was pretreated via medium-pressure liquid chromatography (MPLC) to obtain the target fraction 3 (Fr3). Fr3 was further purified using HPLC to finally obtain the target fraction 3-1, which was identified as kaempferol 3,4′-di-O-β-D-glucopyranoside through NMR and mass spectrometry. To further explore the free radical scavenging activity of this compound, its DPPH scavenging ability was determined, and two proteins related to the antioxidant pathway were used for molecular docking. The results revealed that the chromatographic strategy used in this study was efficient and reliable in separating high−purity antioxidants from rape pollen. A strategy such as this, meanwhile, also holds promise for qualitatively identifying and specifically isolating active compounds from other natural products.

Medium- and High-Pressure Integrated Chromatographic Strategies for the Isolation and Purification of Free Radical Inhibitors from Dracocephalum heterophyllum

Dracocephalum heterophyllum has been reported as a traditional Tibetan medicine with diverse therapeutic benefits for the effective treatment of various diseases. However, only a few reports on its free radical inhibitors are limited due to its complex chemical composition and difficult isolation and purification processes. In this study, five free radical inhibitors are isolated by an integrated chromatographic method from Dracocephalum heterophyllum, followed by an investigation of the in vitro antioxidant activity utilizing 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Medium-pressure liquid chromatography was used for the pretreatment of the crude extract of Dracocephalum heterophyllum and targeted separation and purification of the free radical inhibitors using high-pressure liquid chromatography; the antioxidant peaks are recognized by the separation and purification process in combination with an online HPLC-DPPH system. Five free radical inhibitors with purity higher than 95% were obtained, namely xanthotoxol, 5-hydroxy-8-methoxypsoralen, luteolin, methyl rosmarinate, and ethyl rosmarinate. Finally, DPPH assays are performed, and their IC50 values for isolated compounds are 250.39 ± 13.32 μM, 26.91 ± 1.93 μM, 66.87 ± 14.33 μM, 21.99 ± 3.17 μM, and 36.96 ± 1.72 μM, respectively. This method is effective in isolating free radical inhibitors from Dracocephalum heterophyllum, and it has the potential to be adopted for the isolation of antioxidants from other plants of medicinal value as well.

Integrated chromatographic approach for the discovery of gingerol antioxidants from Dracocephalum heterophyllum and their potential targets

As a traditional Tibetan medicine, Dracocephalum heterophyllum has many benefits, but due to the complicated procedures of separation and purification of its chemical constituents, there are few reports on gingerols. In this study, four antioxidative gingerols were isolated from Dracocephalum heterophyllum by an integrated chromatographic approach. Antioxidant activity was then determined by in vitro experiments and its potential targets of action were investigated. First, the extract was pretreated using silica gel, MCI GEL®CHP20P, and diol and spherical medium pressure columns, while the antioxidant peaks were identified using an online HPLC-1,1-diphenyl-2-picrylhydrazyl system. Then, the antioxidant peaks were directionally separated and purified by high pressure liquid chromatography to obtain four gingerols with a purity higher than 95%, namely 5-methoxy-6-gingerol, 6-shogaol, 6-paradol, and diacetoxy-6-gingerdiol. Finally, 1,1-diphenyl-2-picrylhydrazyl assays and cellular antioxidant experiments were carried out, and molecular docking was used to explore potential antioxidant targets. The isolated gingerols upregulated the activity of antioxidant enzymes, including superoxide dismutase (SOD), heme oxygenase-1 (HO-1) and NADPH oxidase 2 (NOX2), while they had little effect on the activity of nadph:quinone oxidoreductase-1 (NQO1). This method can efficiently prepare and isolate antioxidative gingerols from Dracocephalum heterophyllum, and it can be extended to isolate antioxidants from other natural products.

The Isolation and Preparation of Samwinol from Dracocephalum heterophyllum and Prevention on Aβ25-35-Induced Neuroinflammation in PC-12 Cells

Dracocephalum heterophyllum (D. heterophyllum) is a traditional Chinese Tibetan medicine that has been used for the treatment of lymphitis, hepatitis, and bronchitis. However, only a few selected chemical components are currently obtained from D. heterophyllum, which limits its further pharmacological applications. In this study, we have obtained samwinol from D. heterophyllum by medium- and high-pressure liquid chromatography separation for the first time. Thereafter, we investigated the protective actions of samwinol against amyloid beta protein fragment 25-35 (Aβ_25-35) induced neurotoxicity in cultured rat pheochromocytoma PC-12 cells and explored its underlying mechanisms of action. The results indicated that samwinol could increase cell viability and inhibit the production of reactive oxygen species (ROS) and mitochondria-derived ROS, as assessed by MTT assay, Giemsa staining, and flow cytometry assay. Through Western blot analysis, it was found that samwinol substantially inhibited the phosphorylation of ERK(1/2) and promoted the expression of HO-1 and Nrf2. The data obtained from molecular docking were also consistent with the above conclusions. All of these results showed that samwinol from D. heterophyllum can display significant anti-neuroinflammatory and antioxidant activities in vitro, which are associated with the suppression of ERK/AKT phosphorylation and the activation of the Nrf2/HO-1 signaling pathway. In the future, additional in-depth mechanism studies will be carried out to provide more evidence for the potential of samwinol in the treatment of Alzheimer's disease.