Polymethoxyflavones: an updated review on pharmacological properties and underlying molecular mechanisms

Mechanistic Insights into Polyphenols-mediated Squalene Epoxidase Inhibition: Computational Models and Experimental Validation for Targeting Cholesterol Biosynthesis

Squalene epoxidase is a key enzyme in sterol biosynthesis, particularly in cholesterol metabolism. Its inhibition has emerged as a promising therapeutic strategy for metabolic disorders, hypercholesterolemia, and certain infections. Herein, we investigated the SQLE inhibitory potential of six polyphenolic compounds, identified through in silico virtual screening of a large natural phenolic library and selected for high predicted binding affinity and structural diversity. Molecular docking demonstrated strong interactions between these candidates and SQLE, with curcumin exhibiting the highest binding affinity (-10.1 kcal/mol). Molecular dynamics simulations confirmed stable interactions for all compounds, highlighting curcumin, piceatannol, and pterostilbene as particularly favorable. Their strong binding free energies were further supported by MM/PBSA calculations (-36.62 ± 4.17, -31.32 ± 3.77, and -32.01 ± 1.34 kcal/mol, respectively), corroborated by free energy landscape analysis. ADMET profiling revealed diverse pharmacokinetic properties among the six polyphenolics. In vitro testing confirmed curcumin as the most potent inhibitor (IC50 = 1.88 ± 0.21 µM), with piceatannol (2.55 ± 0.30 µM) and pterostilbene (2.69 ± 0.11 µM) following closely. Enzyme kinetics demonstrated that these three compounds act as competitive inhibitors targeting the enzyme's active site. Collectively, these findings highlight the combined power of computational and experimental approaches for identifying novel SQLE inhibitors.

Streamlined and green chromatographic approach for the determination of oxygen heterocyclic compounds in foodstuffs via miniaturised extraction

A great number of plants, principally belonging to Apiaceae and Rutaceae families, contain oxygen heterocyclic compounds (OHCs), namely coumarins, furanocoumarins and polymethoxyflavones. Coumarin and its derivatives are widely exploited as therapeutic agents but also as flavouring agents in foods. Among all the OHCs, the content of coumarin is the only one strictly regulated in foods. The aim of this research was to investigate the amount of coumarin and other thirty-five OHCs in thirty foods flavoured with cinnamon, Citrus and carrot products to monitor the daily intake of OHCs by food. The primary objective of this study was to assess the potential for a greener approach to miniaturise the extraction procedure, thereby reducing the amount of solvents used and the time required. Liquid chromatography coupled with triple-quadrupole mass spectrometry detector was the approach of choice to determine the amount of OHCs in the samples of our interest.

Antimicrobial Potential of Polyphenols: Mechanisms of Action and Microbial Responses-A Narrative Review

Polyphenols (PPs) are recognized as bioactive compounds and antimicrobial agents, playing a critical role in enhancing food safety, preservation, and extending shelf life. The antimicrobial effectiveness of PPs has different molecular and biological reasons, predominantly linked to their hydroxyl groups and electron delocalization, which interact with microbial cell membranes, proteins, and organelles. These interactions may reduce the efficiency of metabolic pathways, cause destructive damage to the cell membrane, or they may harm the proteins and nucleic acids of the foodborne bacteria. Moreover, PPs exhibit a distinctive ability to form complexes with metal ions, further amplifying their antimicrobial activity. This narrative review explores the complex and multifaceted interactions between PPs and foodborne pathogens, underlying the correlation of their chemical structures and mechanisms of action. Such insights shed light on the potential of PPs as innovative natural preservatives within food systems, presenting an eco-friendly and sustainable alternative to synthetic additives.

Polymethoxylated flavone variations and in vitro biological activities of locally cultivated Citrus varieties in China

Citrus peels are rich in polymethoxylated flavones (PMFs), which have beneficial health and pharmacological properties. In this study, the profiles, variations, and biological activities of PMFs in the peel extracts of 27 Citrus varieties (eight species) native to China were investigated. UPLC-QTOF-MS/MS analysis revealed that mandarin accumulated more diversity and higher detectable PMF contents. Wangcangzhoupigan (ZPG) possessed the highest antioxidant capacity. Gailiangcheng (GLC) and Bingtangcheng (BTC), sweet oranges showed excellent inhibitory effects against pancreatic lipase and α-glucosidase, respectively. Most citrus extracts effectively inhibited the production of ROS and pro-inflammatory cytokines, while increasing the accumulation of anti-inflammatory cytokines. In addition, Limeng (LM), Cupig-oushigan (GSG), and Yanxiwanlu (YXWL) showed anti-proliferative effects against DU145 and PC3 cancer cells. This study provides a comprehensive PMF profile and biological activities of various citrus species and will benefit future functional citrus breeding practices aimed at designing plants rich in total or specific PMFs for health benefits.

Bioassay-guided isolation and structure elucidation of anti-mycobacterium tuberculosis compounds from Galatella grimmii (Regel & Schmalh.) Sennikov

BACKGROUND

Galatella is a genus in the family Asteraceae, represented by 35-45 species. Considering the high effectiveness of the ethyl acetate (EtOAc) fraction of G. grimmii against Mycobacterium tuberculosis (MIC = 0.5 µg/mL), a bioassay-directed fractionation of this extract was carried out.

METHODS

The methanolic extract of the aerial parts of G. grimmii was obtained using maceration, then it was suspended in water and partitioned with petroleum ether, dichloromethane (CH2Cl2), EtOAc, and n-butanol (n-BuOH), successively. The most potent fraction (EtOAc), was selected for further isolation by Sephadex LH-20 and semi-preparative HPLC to obtain active compounds.

RESULTS

Fractionation of the EtOAc solvent fraction resulted in the characterization of five compounds, among them, compounds 1 and 2 showed the highest anti-mycobacterial effects with MICs of 0.062 and 1.00 µg/mL against H37Rv M. tuberculosis, respectively, which were higher than those of rifampin (MIC of 1.25 µg/mL) and isoniazid (MIC of 0.31 µg/mL), as positive controls. Also, compound 1 ​​inhibited all tested strains of drug-resistant Mycobacterium (MDR and XDR). Notably, the isolated compounds have been reported for the first time from G. grimmii.

CONCLUSION

Due to the potent anti-mycobacterial effect of isolated compounds from G. grimmii, this study could pave the way for developing a novel class of natural anti-tuberculosis compounds.

Extraction and Chromatographic Approaches for Coumarin, Furocoumarin, and Polymethoxyflavone Characterization in Foods

Oxygen heterocyclic compounds play a beneficial role in plants, and their presence in foods, such as Citrus fruits, cinnamon, carrots, and parsley, has been documented in recent years. Published research articles reported several extractions and chromatographic techniques for their determination. The aim of this review was to take into consideration the research articles published from 2016 to 2024 in which the authors developed extraction and chromatographic analysis methods of oxygen heterocyclic compounds in foods. The objective of this review was to assist researchers in choosing the best approach for their future work by identifying all the possible approaches to characterize coumarins, furocoumarins, and polymethoxyflavones in foodstuffs.

Effects of Citrus depressa Hayata juice on high-fat diet-induced obesity in HBV transgenic mice

The present study investigated the potential anti-obesity properties of Citrus depressa Hayata (CDH) juice in HBV transgenic mice, as well as the impact of fermentation on the effectiveness of the juice. The results revealed that fermentation increased the levels of polyphenols and hesperidin in CDH juice. The animal study demonstrated that both juices were effective in mitigating the weight gain induced by a high-fat diet by correcting metabolic parameter imbalances, reducing hepatic lipid accumulation, and reversing hepatic immune suppression. Furthermore, fermented juice exhibited superior efficacy in managing body weight and inhibiting the expansion of white adipose tissue (WAT). Fermented juice significantly enhanced adiponectin production and PPARγ expression in WAT, while also reducing hypertrophy. This study offers valuable insights into the potential role of CDH juices in combating obesity associated with high fat consumption and underscores the promise of CDH juice as a functional beverage.

Hydroxylated Tetramethoxyflavone Affects Intestinal Cell Permeability and Inhibits Cytochrome P450 Enzymes

Tetramethoxyflavones (TMFs) found in the Citrus genus have garnered considerable interest from food scientists and the health food industry because of their promising biological properties. Nonetheless, there are currently limited data available regarding the effectiveness and bioavailability of "hydroxylated TMFs", which are flavones known for their potential in disease prevention through dietary means. This study aims to provide insights into the chemical and biological properties of hydroxylated TMF and evaluates its effects on intestinal cell permeability and cytochrome P450 (CYP) inhibition. Liquid chromatography-mass spectrometry (LC-MS) and microsomes analyze the TMFs and hydroxylated TMFs, elucidating cell penetration and metabolic inhibition potential. 3H7-TMF shows the fastest (1-h) transport efficiency in intestinal cells. The Caco-2 cell model exhibits significant transport and absorption efficiency. Dissolved hydroxyl-TMF with hydrophilicity possibly permeates the gut. 3H7-TMF has higher transport efficiency (46%) 3H6-TMF (39%). IC50 values of TMFs (78-TMF, 57-TMF, 3H7-TMF, 3H6-TMF) against CYP enzymes (CYP1A2, CYP2D6, CYP2C9, CYP2C19, CYP3A4) range from 0.15 to 108 μM, indicating potent inhibition. Hydroxyl groups enhance TMF hydrophilicity and membrane permeability. TMFs display varied inhibitory effects due to hydroxyl and methoxy hindrance. This study underscores the strong CYP inhibitory capabilities in these TMFs, implying potential food-drug interactions if used in medicines or supplements. These findings can also help with food nutrition improvement and pharma food developments through innovative approaches for Citrus waste valorization.