Optimization of flavanones extraction by modulating differential solvent densities and centrifuge temperatures

Biological Activities and Solubilization Methodologies of Naringin

Naringin (NG), a natural flavanone glycoside, possesses a multitude of pharmacological properties, encompassing anti-inflammatory, sedative, antioxidant, anticancer, anti-osteoporosis, and lipid-lowering functions, and serves as a facilitator for the absorption of other drugs. Despite these powerful qualities, NG's limited solubility and bioavailability primarily undermine its therapeutic potential. Consequently, innovative solubilization methodologies have received considerable attention, propelling a surge of scholarly investigation in this arena. Among the most promising solutions is the enhancement of NG's solubility and physiological activity without compromising its inherent active structure, therefore enabling the formulation of non-toxic and benign human body preparations. This article delivers a comprehensive overview of NG and its physiological activities, particularly emphasizing the impacts of structural modification, solid dispersions (SDs), inclusion compound, polymeric micelle, liposomes, and nanoparticles on NG solubilization. By synthesizing current research, this research elucidates the bioavailability of NG, broadens its clinical applicability, and paves the way for further exploration and expansion of its application spectrum.

An optimized solvent extraction and characterization of unidentified flavonoid glucuronide derivatives from spinach by UHPLC-HR-QTOF-MS

A rapid, sensitive analytical method using ultra-high-pressure liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-HR-QTOF-MS) was developed for the identification and quantification of flavonoids from spinach. The extraction efficiency of flavonoids was evaluated by different solvents such as acetone, ethanol, methanol, acetone: water (70:30), ethanol: water (70:30) and methanol: water (70:30). Flavonoid identification was achieved by UV spectra, high resolution accurate mass and their fragmentation pattern. The precursor and product ions were recorded by both broadband collision ion dissociation (bbCID) and multiple reaction monitoring (MRM) techniques. Different collision energies (5, 10, 15, 20, 40, and 70 eV) were optimized to obtain the mass spectra of flavonoids in positive and negative ionization modes. For the first time, five minor flavonoid glucuronide derivatives were identified in spinach. MRM and bbCID provided glucuronide fingerprint ions at m/z 175.0278 and m/z 113.0257 respectively in negative ionization mode. The quantification of identified flavonoids was achieved by 5,3',4'-trihydroxy-3-methoxy-6:7-methylen-dioxyflavone-4'-β-D-glucuronide which was purified by semi-preparatory HPLC. The purity of the isolated compound was confirmed by NMR analysis. The identified 5,3',4'-trihydroxy-3-methoxy-6:7-methylen-dioxyflavone-4'-β-D-(2'-O-feurloyl-glucuronide) was the prominent flavonoid and the level was significantly higher in the acetone fraction (2.95 ± 0.16 µg/g FW). This study demonstrates the systematic identification of potential bioactive compounds especially glucuronide derivatives from spinach.

Rapid ultra-high-performance liquid chromatography/quadrupole time-of-flight tandem mass spectrometry and selected reaction monitoring strategy for the identification and quantification of minor spinacetin derivatives in spinach

RATIONALE

Spinach is green leafy vegetable which is a rich source of flavonoids, phenolic acids, carotenoids, and vitamins A, C and E. It contains unique flavonoids which have significant anticarcinogenic, antiinflammatory and free radical scavenging activities. The present study reports the systematic identification and quantification of novel flavonoids by ultra-high-performance liquid chromatography with quadrupole time-of-flight tandem mass spectrometry (UHPLC/HR-QTOFMS).

METHODS

An ultrasonication technique was used for the extraction of flavonoids from spinach. A rapid and reliable analytical method was established for the identification of flavonoids from methanolic extract. Flavonoids were characterized by their ultraviolet (UV) spectra, high-resolution accurate masses and MS/MS fragmentation pathways obtained using electrospray ionization (ESI). Furthermore, precursor ions from the intact molecule, and the resulting product ions, were monitored by selected reaction monitoring (SRM) with different collision energies in positive and negative ion mode.

RESULTS

For the first time, five minor spinacetin derivatives were identified under optimized SRM and broadband collision-induced dissociation (+bbCID) conditions. Fragmentation pathways were proposed for spectra obtained in ESI positive ion mode. The use of HR-QTOFMS and SRM allowed us to differentiate between molecules with the same nominal mass. The identified spinacetin derivatives were found to be acylated with ferulic and coumaric acids.

CONCLUSIONS

UHPLC interfaced with HR-QTOFMS in combination with SRM provides a rapid, reliable and highly sensitive method for the identification of flavonoids, and potentially other bioactive compounds, in a complex matrix.

Optimized method for the quantification of pyruvic acid in onions by microplate reader and confirmation by high resolution mass spectra

The present study describes the rapid microplate method to determine pyruvic acid content in different varieties of onions. Onion juice was treated with 2,4-dinitrophenylhydrazine to obtain hydrazone, which was further treated with potassium hydroxide to get stable colored complex. The stability of potassium complex was enhanced up to two hours and the structures of hydrazones were confirmed by LC-MS for the first time. The developed method was optimized by testing different bases, acids with varying concentrations of dinitrophenyl hydrazine to get stable color and results were comparable to developed method. Repeatability and precision showed <9% relative standard deviation. Moreover, sweet onion juice was stored for four weeks at different temperatures for the stability; the pyruvate remained stable at all temperatures except at 25°C. Thus, the developed method has good potential to determine of pungency in large number of onions in a short time using minimal amount of reagents.

Modulation of flavanone and furocoumarin levels in grapefruits (Citrus paradisi Macfad.) by production and storage conditions

Grapefruits grown under organic or conventional systems were analyzed for 6,7-dihydroxybergamottin (DHB) and flavanones using HPLC, and DPPH activity and ORAC using a micro-plate reader. Grapefruits harvested in November 2008 (E-1) and February 2010 (E-2) were stored at room temperature (RT) and 9 °C for four weeks. Higher levels of DHB were observed in conventional grapefruits during the second (4.7 ± 0.2 μg/g), third (1.5 ± 0.2 μg/g) and fourth (2.5 ± 0.2 μg/g) week of storage at room temperature in E2. Among flavonoids analyzed, narirutin (666.7 ± 33.9 μg/g), neohesperidin (17.5 ± 1.3 μg/g), didymin (75.5 ± 5.6 μg/g) and poncirin (130.8 ± 10.4 μg/g) levels were significantly higher (P⩽0.05) in organic grapefruits over conventional grapefruits at harvest and storage in E-1. Although DPPH levels were moderately correlated with grapefruit flavanone content, variability in the individual flavanone activity was pronounced, resulting in non-significant differences in antioxidant activity between organic and conventional grapefruits.