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Jerusalem artichoke (JA, Helianthus tuberosus L.) has been researched extensively due to its wide range of uses, but there are limited studies on its flowers. In this study, we report the first detailed phytochemical study on JA flowers, which yielded 21 compounds. Compound 4 was identified as a major water-soluble yellow pigment of JA flowers. In addition, the methanol extract of JA flowers and the isolates were evaluated for their antioxidant and α-glucosidase inhibitory activities. Among the tested compounds, compound 13 showed the strongest ABTS+ free radical scavenging activity with SC50 value of 2.30 ± 0.13 μg/mL, and compound 6 showed most potent α-glucosidase inhibitory activity with inhibition rate of 60.0% ± 10.3% at a concentration of 250 μg/mL. Results showed that methanol extract of JA flowers exhibited antioxidant and α-glucosidase inhibitory activities which could be attributed to its phenolic ingredients including chlorogenic acid derivatives, flavonoids and phenols.
A simple, precise, and rapid method was developed for the determination of four flavonoids, apigenin (AP), tricin (TR), luteolin (LU), and 4′-methoxy-tricin (MTR) in the Tibetan herbal medicine of Pyrethrum tatsienense by the high-performance liquid chromatographic technique coupled with photodiode array detection (DAD). A C18 reversed-phase column and a linear gradient elution system with acetonitrile-tetrahydrofuran-1% acetic acid as the mobile phase were employed. The method is validated in terms of the limit of detection (LOD), linearity, precision, and accuracy. The LODs were 48 ng/mL for AP, 75 ng/mL for TR, 88 ng/mL for LU, and 59 ng/mL for MTR, respectively. An excellent linear response was observed over the range specified for all analytes, as confirmed by the correlation coefficient with which from 0.9995 to 0.9999. The intraday RSDs ranged from 0.59 to 2.60%, and the interday RSDs were not higher than 0.05. The accuracy of the method was confirmed with an average recovery ranging from 95.9 to 100.0%. Since the extraction conditions can affect the extraction efficiency, nine different extracts of P. tatsienense were analyzed using different extraction solvents and extraction times. The contents of the four flavonoids in the extract of P. tatsienense were successfully determined within 18 min.
The traditional Tibetan medicine Oxytropis falcata Bunge, in the Leguminosae family, is widely used in the west area owing to its significant anti-inflammatory and analgesic activities. O. falcata is rich in flavonoids, which are the main secondary metabolites and key bioactive components of this plant. Up to now, 91 flavonoids have been isolated from O. falcata, including isoflavone, flavone, flavonone, flavonol, homoisoflavonoid, chalcone, dihydrochalcone, chalcone dimers, and pterocarpans. The flavonoids in O. falcata have good anti-inflammatory and analgesic activities, which are comparable to those of a positive drug control (indomethacin). Furthermore, these flavonoids exhibit antibacterial, antioxidant, antitumour, anti-cardiovascular disease, and haemostatic activities. However, to date, O. falcata has not been reviewed comprehensively. Herein, the main secondary metabolites, biosynthetic pathways, and bioactivities of O. falcata are discussed.
Asterothamnus centrali-asiaticus, a kind of characteristic shrub abundant in grassland and desert areas, has been used as forage fodder for camels and goats in Central Asia, and this plant also plays a critical role in the maintenance of desert grassland ecosystems as a result of its tolerance to poor soils and sand burial. However, its chemical composition has been rarely reported. In this study, phytochemical investigation of this pasturage was performed and three new triterpenoid saponins (1-3) were isolated together with nine known triterpenoid saponins (4-12) using preparative two-dimensional reversed-phase liquid chromatography/hydrophilic interaction chromatography (2D RPLC/HILIC). Their structures were elucidated via diverse spectroscopic analyses, including infrared (IR) spectrometry, high-resolution electrospray ionization mass spectrometry (HR-ESIMS), and one-dimensional (1D) and 2D nuclear magnetic resonance (NMR). All isolated triterpenoid saponins (1-12) were reported from this genus for the first time, and they were further evaluated for their cytotoxicity against four cancer cell lines (A549, HepG2, MGC-803, and MFC), which indicated that compound 11 showed potent cytotoxicity against the HepG2 cell line, with an IC50 value of 6.85 μg/mL.
A new isocoumarin, along with 10 known compounds, was isolated from the aerial parts of Aconitum gymnandrum. Their structures were elucidated by spectroscopic methods including extensive 1D and 2D NMR techniques. Among the known compounds, compound 11 was obtained as a natural product for the first time, which was previously reported as a synthetic product. In addition, compounds 1-5, 7 and 9 were tested for their cytotoxicity against four human cancer cell lines. The results showed that compounds 3, 4 and 7 displayed cytotoxicity against lung cancer A549 and gastric cancer MGC80, respectively, whereas 5 and 9 showed selective cytotoxicity against hepatocellular carcinoma HepG2.
A new flavonoid, along with 16 known ones, was separated from the aerial parts of Asterothamnus centrali-asiaticus. Their structures were elucidated by extensive spectroscopic methods, including 1D and 2D NMR techniques and HRESIMS. To confirm the structure of the new compound, computational prediction of its 13C chemical shifts was performed. All of the 17 flavonoids were reported from A. centrali-asiaticus for the first time. In addition, all flavonoids were evaluated for their antioxidant and α-glucosidase inhibitory activities. The results showed that 10 of them exhibited antioxidant activity. Meanwhile, four flavonoids displayed α-glucosidase inhibitory effect with IC50 values ranging from 38.9 to 299.7 μM.
A capillary zone electrophoresis method was developed for simultaneous determination of nine flavonoids, including two rare flavonols, in Tibetan medicine Anaphalis margaritacea. Baseline separation was performed at pH 9.6 with 25 mM Na(2)B(4)O(7) and 10 mM NaH(2)PO(4) buffer solution, 20 kV as driving voltage and 275 nm as detection wavelength. Repeatability tests showed that the R.S.D. of both intra- and inter-day migration times and peak areas were less than 5%. Recovery results ranged from 87.9% to 106.1%. Samples of A. margaritacea extracts were analyzed using the validated method, which is useful for its quality control.