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ABSTRACT Persea americana Mill., Lauraceae, commonly known as the avocado, is native to tropical and subtropical regions, including Brazil. From the leaves of P. americana, one previously undescribed flavonol glycoside (1) together with ten known flavonoids (2-11), four megastigmane glycosides (12-15) and two lignans (16-17) were isolated. Their structures were determined by extensive spectroscopic methods including 1D- and 2D-nuclear magnetic resonance and mass spectrometry data. This is the first investigation that reports megastigmane glycoside and lignan classes within the genus Persea. All the isolated compounds have been assessed through the cell survival of larval zebrafish following neomycin-induced damage and the cell viability of a House Ear Institute-Organ of Corti 1 mouse auditory cell line. Among the tested compounds, juglanin (2) and (+)-lyoniresinol (16) showed significant cell regeneration in neomycin-damaged hair cell without cellular toxicity.
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Chemical investigation of the plant Tristemma hirtum P. Beauv (Melastomataceae) resulted to the isolation of a new flavonol glycoside named quercetin-7-O-α-D-arabinofuranoside (1), together with nine known compounds including 3′-hexadecanoyl-2′-(9aZ)-tetradecanoyl-glycerol 1′-O-[β-D-galactopyranosyl-(1″ → 6″)-α-D-galactopyranoside] (2), arjunolic acid (3), β-sitosterol-3-O-β-D-glucopyranoside (4), terminolic acid (5), quercetin (6), asiatic acid (7), maslinic acid (8), 1β-O-galloylpedunculagin (9) and 6-hydroxyapigenin 7-O-β-D-glucopyranoside (10) from the methanol extract using normal and reversed phase column chromatography. The structures of these compounds were determined by comprehensive interpretation of their spectral data mainly including 1D- 2D-NMR (¹H-¹H COSY, HSQC, and HMBC) spectroscopic and ESI-TOF-MS mass spectrometric analysis.
Subject(s)
Chromatography , Melastomataceae , Methanol , Plants , QuercetinABSTRACT
Objective: Kalanchoe hybrida (Crassulaceae) is naturalized throughout all the island of Taiwan in China. The preliminary bioassay-guided fractionation of the crude extract of K. hybrida exhibited that the chloroform and n-butanol fractions possessed potent cytotoxicity against MCF-7, NCI-H460, and SF-268 tumor cell lines at 50 µg/mL concentration. Therefore, K. hybrida was selected as a target and the chemical constituents from the chloroform and n-butanol fractions of the crude extracts of K. hybrida were identified. The potential constituents were examined for their cytotoxicity against the tumor cell lines. Methods: A combination of conventional chromatographic techniques was performed on the crude extract of K. hybrida. The chemical structures of the purified constituents were identified on the basis of spectroscopic and spectrometric analysis. Results: The purification results had led to the characterization of totally 37 compounds. The isolated compounds 1, 2, and 4–12 were examined for their cytotoxicity in vitro, and bufadienolides 4–8 and flavonol glycoside 11 displayed significant cytotoxicity towards all the tested tumor cell lines among these tested compounds. Conclusion: The results indicated that these principles should be responsible for the bioactivity of corresponding partial fractions. The potential constituents could be further investigated to explore the new natural lead drugs.
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Flavonol glycoside is in clinical trials for treatment of hyperlipidemia. An accurate and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous determination of flavonol glycoside (M0), aglycone (M1) and glucuronide conjugate (M2) in rat plasma. d6-Flavonol glycoside was used as internal standard (IS). After extraction from the plasma by protein precipitation, the analytes and internal standard were separated on a XDB C18 column (50 mm×4.6 mm, 1.8 μm) using a gradient elution procedure. The mobile phase consisted of methanol and water (0.2% formic acid) at a flow rate of 0.6 mL·min−1. The total run time was 4.5 min. Positive electrospray ionization was performed using multiple reaction monitoring (MRM) with transitions of m/z 461.3 → m/z 299.1 for M0, m/z 299.1 → m/z 283.1 for M1, m/z 475.0 → m/z 299.1 for M2, and m/z 467.3 → m/z 305.1 for d6-flavonol glycoside. The method was validated and successfully applied to the pharmacokinetics study of flavonol glycoside in SD rats which were given flavonol glycoside (30 mg·kg−1) by gavage. The Cmaxof M0 is (341 ±106) ng·mL−1 and AUC0−t is (1 960 ±725) h·ng·mL−1, while the Cmaxof M2 is (1 720 ±843) ng·mL−1and AUC0−t is (8 510 ±2 920) h·ng·mL−1. The results suggest that flavonol glycoside existed mainly in the form of M0 and M2 in rats. After flavonol glycoside being hydrolyzed by the intestinal flora, it was absorbed in the form of aglycone and further metabolized to M2 after the first-pass effect. In this paper, the main metabolites of flavonol glycoside in rat plasma were determined for the first time, which provided a basis for the design of clinical pharmacokinetic experiment.
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The study aimed to identify the chemical constituents of Leucaeana leucocephala leaves and evaluate the antioxidant and antimicrobial activities of the extract and compounds. An acylated flavanol glycoside, quercetin - 3-O-(2''-trans-p-coumaryl)-α-rhamnopyranosyl-(1'''→6'')-β-glucopyranoside (1) in addition to quercetin-3-O-α- rhamnopyranosyl-(1'''→2'')-β–glucopyranoside (2), quercetin-7-O-α–rhamnopyranosyl-(1'''→2'')-β-glucopyrano side(3), quercetin-3-O-α- rhamnopyranoside(4), quercetin-3-O-β–glucopyranoside (5), isovitexin( 6), vitexin (7) and quercetin (8) were isolated for the first time from the Leucaeana leucocephala. The antioxidant activity of the extract and the isolated compounds 1, 3 & 4 were evaluated by Reducing Power, FRAP, DPPH, Metal chelating and ABTS assays. Compound (3) recorded the highest antioxidant activity in comparison with the extract and other compounds. The extract and compound 1, 2, 3 and 5 were studied for their antimicrobial activity. Both the extract and compound 1 have significant activity against gm-ve bacteria, moderate to gm +ve and Candida and inactive towards fungi. The structures of compounds were elucidated on the basis of spectral analysis. L. leucocephala possess good antioxidant, antibacterial properties and could serve as free radical inhibitors or scavengers, acting possibly as primary antioxidants and have to be investigated for antiinflammatory and anticancer activities.
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Objective: To study the chemical constituents of flavonoid glycosides in the extract from Ginkgo biloba leaves used for injection. Methods: The constituents of flavonoid glycosides in the 70% ethanol extract from G. biloba leaves were isolated and purified by chromatography over silica gel, MCI, ODS, Sephadex LH-20 columns and RP-HPLC. The structures were identified on the basis of physicochemical properties and spectral data analyses. Results: Sixteen compounds were isolated and identified as 5, 7-dihydroxyl-4'-methoxylflavonol-3-O-rutinoside (1), quercetin-3-O-(2″, 6″-α-L-dirhamnopyranosyl)-β-D-glucoside (2), quercetin- 3-O-[2″-(6‴-p-coumaroyl)-β-D-glucopyranosyl] -α-L-rhamnopyranosyl-7-O-β-D-glucoside (3), isorhamnetin-3-O-(2″, 6″-α-L-dirhamnopyranosyl)-β-D-glucoside (4), rutin (5), luteolin-7-O-β-D-glucoside (6), quercetin-3-O-β-D-glucoside (7), quercetin- 3-O-(2″-β-D-glucopyranosyl)-α-L-rhamnoside (8), kaempferol-3-O-rutinoside (9), quercetin-3-O-α-L-rhamnoside (10), isorhamnetin-3-O-rutinoside (11), apigenin-7-O-β-D-glucoside (12), syringetin-3-O-rutinoside (13), kaempferol-3-O-(2″- β-D-glucopyranosyl)-α-L-rhamnoside (14), quercetin-3-O-α-L-rhamnopyranosyl-2″- (6‴-p-coumaroyl)-β-D-glucoside (15), and kaempferol-3-O-α-L-rhamnopyranosyl-2″- (6‴-p-coumaroyl)-β-D-glucoside (16). Conclusion: UPLC-PDA shows that all the compounds are flavonoid glycosides in the leaves of G. biloba and are marked in the extract and injection. Compound 1 is isolated from this plant for the first time, named flavonol glycoside K.