Enzymatic properties and immobilization of a thermostable prenyltransferase from Aspergillus fumigatiaffinis for the production of prenylated naringenin.

Prenyltransferases catalyze the synthesis of prenylated flavonoids, providing these with greater lipid solubility, biological activity, and availability. In this study, a thermostable prenyltransferase (AfPT) from Aspergillus fumigatiaffinis was cloned and expressed in Escherichia coli. By optimizing induction conditions, the expression level of AfPT reached 39.3 mU/mL, which was approximately 200 % of that before optimization. Additionally, we determined the enzymatic properties of AfPT. Subsequently, AfPT was immobilized on carboxymethyl cellulose magnetic nanoparticles (CMN) at a maximum load of 0.6 mg/mg. Optimal activity of CMN-AfPT was achieved at pH 8.0 and 55 °C. Thermostability assays showed that the residual activity of CMN-AfPT was greater than 50 % after incubation at 55 °C for 4 h. Km and Vmax of CMN-AfPT for naringenin were 0.082 mM and 5.57 nmol/min/mg, respectively. The Kcat/Km ratio of CMN-AfPT was higher than that of AfPT. Residual prenyltransferase activity of CMN-AfPT remained higher than 70 % even after 30 days of storage. Further, CMN-AfPT retained 68 % of its original activity after 10 cycles of reuse. Compared with free AfPT, CMN-AfPT showed higher catalytic efficiency, thermostability, metal ion tolerance, substrate affinity, storage stability, and reusability. Our study presents a thermostable prenyltransferase and its immobilized form for the production of prenylated flavonoids in vitro.

Flavonoids From the Aerial Parts of Sophora tonkinensis and Their Potential Anti-Inflammatory Activities.

Four undescribed prenylated flavonoids, sophoratones A-D (1-4), and 17 known flavonoids, were obtained from the aerial parts of Sophora tonkinensis. Their structures with absolute configurations were elucidated by detailed interpretation of NMR spectroscopy, mass spectrometry, and ECD calculations. Meanwhile, the ability of these compounds to inhibit the release of nitric oxide (NO) by a lipopolysaccharide induced mouse in RAW 264.7 cells was assayed. The results indicated that some compounds exhibited clear inhibitory effects, with IC50 ranging from 19.91±1.08 to 35.72±2.92 µM. These results suggest that prenylated flavonoids from the aerial parts of S. tonkinensis could potentially be used as a latent source of anti-inflammatory agents.

Mechanistic study of the antibacterial potential of the prenylated flavonoid auriculasin against Escherichia coli.

Bacterial resistance is spreading in an alarming manner, outpacing the rate of development of new antibacterial agents and surging the need for effective alternatives. Prenylated flavonoids are a promising class of natural antibiotics with reported activity against a wide range of resistant pathogens. Here, a large library of natural flavonoids (1718 structures) was virtually screened for potential candidates inhibiting the B-subunit of gyrase (Gyr-B). Twenty-eight candidates, predominated by prenylated flavonoids, appeared as promising hits. Six of them were selected for further in vitro antibacterial and Gyr-B enzyme inhibitory activities. Auriculasin is presented as the most potent antibacterial candidate, with a MIC ranging from 2 to 4 µg/ml against two clinically isolated multidrug-resistant Escherichia coli strains. Mechanistic antibacterial analysis revealed auriculasin inhibitory activity towards the Gyr-B enzyme on the micromolar scale (IC50 = 0.38 ± 0.15 µM). Gyr-B interaction was further detailed by conducting an isothermal titration calorimetric experiment, which revealed a competitive inhibition with a high affinity for the Gyr-B active site, achieved mostly through enthalpic interactions (ΔGbinding = -10.69 kcal/mol). Molecular modeling and physics-based simulations demonstrated the molecule's manner of fitting inside the Gyr-B active site, indicating a very potential nucleus for the future generation of more potent derivatives. To conclude, prenylated flavonoids are interesting antibacterial candidates with anti-Gyr-B mechanism of action that can be obtained from a plant-derived flavonoid.

Chemical Constituents of Macaranga occidentalis, Antimicrobial and Chemophenetic Studies.

Medicinal plants are known as sources of potential antimicrobial compounds belonging to different classes. The aim of the present work was to evaluate the antimicrobial potential of the crude extract, fractions, and some isolated secondary metabolites from the leaves of Macaranga occidentalis, a Cameroonian medicinal plant traditionally used for the treatment of microbial infections. Repeated column chromatography of the ethyl acetate and n-butanol fractions led to the isolation of seventeen previously known compounds (1-17), among which three steroids (1-3), one triterpene (4), four flavonoids (5-8), two stilbenoids (9 and 10) four ellagic acid derivatives (11-14), one geraniinic acid derivative (15), one coumarine (16), and one glyceride (17). Their structures were elucidated mainly by means of extensive spectroscopic and spectrometric (1D and 2D NMR and, MS) analysis and comparison with the published data. The crude extract, fractions, and isolated compounds were all screened for their antimicrobial activity. None of the natural compounds was active against Candida strains. However, the crude extract, fractions, and compounds showed varying levels of antibacterial properties against at least one of the tested bacterial strains, with minimal inhibitory concentrations (MICs) ranging from 250 to 1000 µg/mL. The n-butanol (n-BuOH) fraction was the most active against Escherichia coli ATCC 25922, with an MIC value of 250 µg/mL. Among the isolated compounds, schweinfurthin B (10) exhibited the best activity against Staphylococcus aureus NR 46003 with a MIC value of 62.5 µg/mL. In addition, schweinfurthin O (9) and isomacarangin (6) also exhibited moderate activity against the same strain with a MIC value of 125 µg/mL. Therefore, pharmacomodulation was performed on compound 6 and three new semisynthetic derivatives (6a-c) were prepared by allylation and acetylation reactions and screened for their in vitro antimicrobial activity. None of the semisynthetic derivatives showed antimicrobial activity against the same tested strains. The chemophenetic significance of the isolated compounds is also discussed in this paper.

Prenylated Flavonoids in Topical Infections and Wound Healing.

The review presents prenylated flavonoids as potential therapeutic agents for the treatment of topical skin infections and wounds, as they can restore the balance in the wound microenvironment. A thorough two-stage search of scientific papers published between 2000 and 2022 was conducted, with independent assessment of results by two reviewers. The main criteria were an MIC (minimum inhibitory concentration) of up to 32 µg/mL, a microdilution/macrodilution broth method according to CLSI (Clinical and Laboratory Standards Institute) or EUCAST (European Committee on Antimicrobial Susceptibility Testing), pathogens responsible for skin infections, and additional antioxidant, anti-inflammatory, and low cytotoxic effects. A total of 127 structurally diverse flavonoids showed promising antimicrobial activity against pathogens affecting wound healing, predominantly Staphylococcus aureus strains, but only artocarpin, diplacone, isobavachalcone, licochalcone A, sophoraflavanone G, and xanthohumol showed multiple activity, including antimicrobial, antioxidant, and anti-inflammatory along with low cytotoxicity important for wound healing. Although prenylated flavonoids appear to be promising in wound therapy of humans, and also animals, their activity was measured only in vitro and in vivo. Future studies are, therefore, needed to establish rational dosing according to MIC and MBC (minimum bactericidal concentration) values, test potential toxicity to human cells, measure healing kinetics, and consider formulation in smart drug release systems and/or delivery technologies to increase their bioavailability.

Exploration of Antimicrobial Ingredients in Psoralea corylifolia L. Seed and Related Mechanism against Methicillin-Resistant Staphylococcus aureus.

With the abuse of antibiotics, bacterial antibiotic resistance is becoming a major public healthcare issue. Natural plants, especially traditional Chinese herbal medicines, which have antibacterial activity, are important sources for discovering potential bacteriostatic agents. This study aimed to develop a fast and reliable method for screening out antimicrobial compounds targeting the MRSA membrane from Psoralea corylifolia Linn. seed. A UPLC-MS/MS method was applied to identify the prenylated flavonoids in major fractions from the extracts of Psoralea corylifolia Linn. seed. The broth microdilution method was used to determine the minimum inhibitory concentrations (MICs) of different fractions and compounds. The morphological and ultrastructural changes of MRSA were determined by scanning electron microscopy (SEM). The membrane-targeting mechanism of the active ingredients was explored by membrane integrity assays, membrane fluidity assays, membrane potential assays, ATP, and ROS determination. We identified eight prenylated flavonoids in Psoralea corylifolia Linn. seed. The antibacterial activity and mechanism studies showed that this type of compound has a unique destructive effect on MRSA cell membranes and does not result in drug resistance. The results revealed that prenylated flavonoids in Psoralea corylifolia Linn. seeds are promising candidates for the development of novel antibiotic agents to combat MRSA-associated infections.

Prenylated Flavonoids with Potential Antimicrobial Activity: Synthesis, Biological Activity, and In Silico Study.

Prenylated flavonoids are an important class of naturally occurring flavonoids with important biological activity, but their low abundance in nature limits their application in medicines. Here, we showed the hemisynthesis and the determination of various biological activities of seven prenylated flavonoids, named 7-13, with an emphasis on antimicrobial ones. Compounds 9, 11, and 12 showed inhibitory activity against human pathogenic fungi. Compounds 11, 12 (flavanones) and 13 (isoflavone) were the most active against clinical isolated Staphylococcus aureus MRSA, showing that structural requirements as prenylation at position C-6 or C-8 and OH at positions C-5, 7, and 4' are key to the antibacterial activity. The combination of 11 or 12 with commercial antibiotics synergistically enhanced the antibacterial activity of vancomycin, ciprofloxacin, and methicillin in a factor of 10 to 100 times against drug-resistant bacteria. Compound 11 combined with ciprofloxacin was able to decrease the levels of ROS generated by ciprofloxacin. According to docking results of S enantiomer of 11 with ATP-binding cassette transporter showed the most favorable binding energy; however, more studies are needed to support this result.

Elucidating the Glucokinase Activating Potentials of Naturally Occurring Prenylated Flavonoids: An Explicit Computational Approach.

Glucokinase activators are considered as new therapeutic arsenals that bind to the allosteric activator sites of glucokinase enzymes, thereby maximizing its catalytic rate and increasing its affinity to glucose. This study was designed to identify potent glucokinase activators from prenylated flavonoids isolated from medicinal plants using molecular docking, molecular dynamics simulation, density functional theory, and ADMET analysis. Virtual screening was carried out on glucokinase enzymes using 221 naturally occurring prenylated flavonoids, followed by molecular dynamics simulation (100 ns), density functional theory (B3LYP model), and ADMET (admeSar 2 online server) studies. The result obtained from the virtual screening with the glucokinase revealed arcommunol B (-10.1 kcal/mol), kuwanon S (-9.6 kcal/mol), manuifolin H (-9.5 kcal/mol), and kuwanon F (-9.4 kcal/mol) as the top-ranked molecules. Additionally, the molecular dynamics simulation and MM/GBSA calculations showed that the hit molecules were stable at the active site of the glucokinase enzyme. Furthermore, the DFT and ADMET studies revealed the hit molecules as potential glucokinase activators and drug-like candidates. Our findings suggested further evaluation of the top-ranked prenylated flavonoids for their in vitro and in vivo glucokinase activating potentials.

Prenylated chromones and flavonoids from Artocarpus heterophyllus with their potential antiproliferative and anti-inflammatory activities.

Two new prenylated chromones, artoheterophines A (1) and B (2), five known prenylated chromones (3-7), as well as five known biogenetically related prenylated flavonoids (8-12) were isolated and characterized from the stems and leaves of A. heterophyllus. Their chemical structures were unambiguously determined through comprehensive spectral data analyses. The antiproliferative and anti-inflammatory effects of all these isolated prenylated chromones and flavonoids were evaluated in vitro. As a result, compounds 1-12 showed notable inhibitory effects against various human cancer cell lines with IC50 values ranging from 0.36 ± 0.02 to 22.09 ± 0.16 µM. Meanwhile, compounds 1-12 exhibited significant inhibitory activities on nitric oxide (NO) production holding IC50 values in the range of 0.48 ± 0.05-19.87 ± 0.21 µM. These research results suggest that the isolation and characterization of these prenylated chromones (1-7) and flavonoids (8-12) holding significant antiproliferative and anti-inflammatory activities could be significant to the discovery and development of new natural anti-tumor and anti-inflammatory drugs. The findings also provides a phytochemical evidence for further development and utilization of the stems and leaves of A. heterophyllus in health and pharmaceutical products.

Promising Antioxidant Activity of Erythrina Genus: An Alternative Treatment for Inflammatory Pain?

The negative impact that oxidative stress has on health is currently known. The complex mechanism of free radicals initiates a series of chain reactions that contribute to the evolution or development of different degenerative disorders. Likewise, these disorders are usually accompanied by inflammatory processes and, therefore, pain. In this sense, reactive oxygen species (ROS) have been shown to promote the nociceptive process, but effective treatment of pain and inflammation still represents a challenge. Over time, it has been learned that there is no single way to relieve pain, and as long as there are no other alternatives, the trend will continue to apply multidisciplinary management, such as promote the traditional use of the Erythrina genus to manage pain and inflammation. In this sense, the Erythrina genus produces a wide range of secondary metabolites, including flavanones, isoflavones, isoflavones, and pterocarpans; these compounds are characterized by their antioxidant activity. Phenolic compounds have demonstrated their ability to suppress pro-oxidants and inhibit inflammatory signaling pathways such as MAPK, AP1, and NFκB. Although there is preclinical evidence supporting its use, the pharmacological effect mechanisms are not entirely clear. Nowadays, there is a fast advancement in knowledge of the disciplines related to drug discovery, but most of nature's medicinal potential has not yet been harnessed. This review analyzes the decisive role that the Erythrina genus could play in managing inflammatory pain mediated by its compounds and its uses as an antioxidant.

Beer Phenolic Composition of Simple Phenols, Prenylated Flavonoids and Alkylresorcinols.

Beer is a fermented beverage with beneficial phenolic compounds and is widely consumed worldwide. The current study aimed to describe the content of three families of phenolic compounds with relevant biological activities: prenylated flavonoids (from hops), simple phenolic alcohols (from fermentation) and alkylresorcinols (from cereals) in a large sample of beers (n = 45). The prenylated flavonoids analyzed were xanthohumol, isoxanthohumol, 6- and 8-prenylnaringenin. The total prenylated flavonoids present in beer ranged from 0.0 to 9.5 mg/L. The simple phenolic alcohols analyzed were tyrosol and hydroxytyrosol, ranging from 0.2 to 44.4 and 0.0 to 0.1 mg/L, respectively. Our study describes, for the first time, the presence of low amounts of alkylresorcinols in beer, in concentrations ranging from 0.02 to 11.0 µg/L. The results in non-alcoholic beer and the differences observed in the phenolic composition among different beer types and styles highlight the importance of the starting materials and the brewing process (especially fermentation) on the final phenolic composition of beer. In conclusion, beer represents a source of phenolic compounds in the diet that could act synergistically, triggering beneficial health effects in the context of its moderate consumption.

Plant Milking Technology-An Innovative and Sustainable Process to Produce Highly Active Extracts from Plant Roots.

We have used an original technology (Plant Milking Technology) based on aeroponic cultivation of plants associated with the gentle recovery of active ingredients from roots. Extraction of bioactive molecules was achieved by soaking the roots, still attached to the living plants, into a nontoxic solvent for a 2 h period. This nondestructive recovery process allows using the same root biomass for successive harvesting dates, in a recyclable way. We have applied this technology to Morus alba L. (mulberry tree), an emblematic tree of the Traditional Chinese Medicine (TCM). Trees were aeroponically grown in large-scale devices (100 m2) and were submitted to nitrogen deprivation to increase the content in active molecules (prenylated flavonoids). The Plant Milking technology applied to Morus alba L. allowed to produce an extract enriched in prenylated compounds (18-fold increase when compared to commercial root extract). Prenylated flavonoids (moracenin A and B, kuwanon C, wittiorumin F, morusin) presented a high affinity for the aged-associated collagenase enzyme, which was confirmed by activity inhibition. In accordance, M. alba extract presents efficient properties to regulate the skin matrisome, which is critical during skin aging. The benefits have been especially confirmed in vivo on wrinkle reduction, in a clinical study that involved aged women. Plant Milking technology is an optimal solution to produce active ingredients from plant roots, including trees, that meet both customer expectations around sustainability, as well as the need for an efficient production system for biotechnologists.

Absolute configuration and anti-cancer effect of prenylated flavonoids and flavonostilbenes from Sophora pachycarpa: Possible involvement of Wnt signaling pathway.

A new prenylated flavonostilbene, namely, alopecurone P together with three known compounds sophoraflavanone G, 2-(4-hydroxyphenyl)-2,3-dihydrobenzo[b]furan-3,4,6-triol and alopecurone J were characterized from the roots of Sophora pachycarpa. The absolute configuration of alopecurones J and P were characterized by comparison of experimental electronic circular dichroism (ECD) spectroscopy and simulated data using time-dependent density functional theory (TDDFT) for possible stereoisomers. The cytotoxic properties of isolated compounds have also been evaluated on two breast cancer cell lines (MCF-7 and MDA-MB-231) and normal cell line (NIH/3T3) using AlamarBlue®, flowcytometry and western blot assays. Alopecurone J and P showed cytotoxic effect on MCF-7 cell line through Wnt signaling pathway. It seems that the presence of lavandulyl substitution in C-8 position of flavanone structure increased the cytotoxic effect.

Prenylated flavonoid-enriched fraction from Maclura tinctoria shows biological activity against Staphylococcus aureus and protects Galleria mellonella larvae from bacterial infection.

BACKGROUND: The Atlantic Forest biome extends along the entire Brazilian coast and is home to approximately 20,000 plant species, many of which are endemic; it is considered one of the hotspot regions of the planet. Several of these species are sources of natural products with biological activities that are still unknown. In this study, we evaluated the antimicrobial activity of 90 extracts derived from native Atlantic Forest tree species against Staphylococcus aureus, an important human and veterinary pathogen. METHODS: Extracts from native Atlantic Forest tree species were evaluated for their antimicrobial activity against S. aureus by in vitro standard methods. Phytochemical fractionation of the extract from Maclura tinctoria was performed by liquid-liquid partitioning. LC-DAD-ESI-MS was used for identification of constituents in the most active fraction. Damage of cells and alterations in the permeability of cell membrane were determined by atomic force microscopy (AFM) and crystal violet uptake assay, respectively. In vivo antimicrobial activity was evaluated using Galleria mellonella larvae infected with S. aureus with survival data collected using the Kaplan-Meier method. RESULTS: Among the organic or aqueous extracts tested here, 26 showed biological activity. Eight species showed relevant results, with a minimum inhibitory concentration (MIC) below 1 mg/mL. Antibacterial activity was registered for three species for the first time. An organic extract from Maclura tinctoria leaves showed the lowest MIC (0.08 mg/mL). Fractionation of this extract by liquid-liquid partitioning led to obtaining fraction 11FO d with a MIC of 0.04 mg/mL. This fraction showed strong activity against veterinary S. aureus isolates and contributed to the increased survival of Galleria mellonella larvae infected with S. aureus ATCC 29213. The bacterial surface was not altered by the presence of 11FO d, and no cell membrane damage was detected. The LC-DAD-ESI/MS analyses identified prenylated flavonoids as the major constituents responsible for the antibacterial activity of this active extract. CONCLUSION: A fraction enriched in prenylated isoflavones and flavanones from M. tinctoria showed in vitro and in vivo efficacy as antistaphylococcal agents. These findings justify the need for further research to elucidate the mechanisms of action of these compounds.

Biologically active prenylated flavonoids from the genus Sophora and their structure-activity relationship-A review.

The genus Sophora (Fabaceae) has been used in traditional medicine for years. Prenylated flavonoids are one of the constituents of Sophora species that play important roles in their biological properties. Different classes of prenylated flavonoids are produced by Sophora spp. including prenylated flavonol (e.g., sophoflavescenol), prenylated flavanone (e.g., sophoraflavanone G), prenylated flavonostilbene (e.g., alopecurones A and B), and prenylated chalcone (kuraridin). Prenylated flavonoids have a more lipophilic structure, which leads to its high affinity to the cell membranes and enhancement of the biological activity, which includes cytotoxicity, antibacterial, anti-inflammatory, and estrogenic activities. However, it is reported that prenylation decreases the plasma absorption but increases the tissue accumulation. The presence of the prenyl or lavandulyl groups on C8 position of flavonoids plays an important role in the biological activity. It seems that prenylated flavonoids have the potential to be developed as new drugs or supplements for human health.

Prenylated flavonoid-standardized extract from seeds of Psoralea corylifolia L. activated fat browning in high-fat diet-induced obese mice.

We investigated the effects of the prenylated flavonoid-standardized extract (PFE) from the seeds of Psoralea corylifolia L. on countering obesity, which increases energy expenditure and stimulates thermogenesis in subcutaneous white adipose tissue (sWAT) and brown adipose tissue (BAT). For 12 weeks, C57BL/6 mice were fed a controlled high-fat diet (HFD) or HFDs with 0.2% or 0.5% w/w PFE. In vitro, the differentiation of 3 T3-L1 cells was used to elicit thermogenesis in the presence of PFE. PFE obviously reduced body weight and fat mass in a dose-dependent manner, increased energy expenditure, improved insulin sensitivity, and prevented hepatic steatosis by increasing lipid oxidation and secretion in HFD-fed mice. Moreover, PFE induced clear browning in sWAT, significantly increased phosphorylation of AMPKα1/2 and p38, increased BAT activity and the differentiation of 3 T3-L1 by increasing the expression of uncoupling protein 1 and other thermogenic genes. Our study showed that PFE prevented obesity by increasing browning and activating thermogenic genes in sWAT and BAT, improving glucose homeostasis, and protecting hepatic steatosis.

Characterization and Identification of Prenylated Flavonoids from Artocarpus heterophyllus Lam. Roots by Quadrupole Time-Of-Flight and Linear Trap Quadrupole Orbitrap Mass Spectrometry.

In this study, a combination of quadrupole time-of-flight mass spectrometry (Q-TOF-MS) and linear trap quadrupole orbitrap mass spectrometry (LTQ-Orbitrap-MS) was performed to investigate the fragmentation behaviors of prenylated flavonoids (PFs) from Artocarpus plants. Fifteen PFs were selected as the model molecules and divided into five types (groups A-E) according to their structural characteristics in terms of the position and existing form of prenyl substitution in the flavone skeleton. The LTQ-Orbitrap-MSn spectra of the [M - H]- ions for these compounds provided a wealth of structural information on the five different types of compounds. The main fragmentation pathways of group A were the ortho effect and retro Diels-Alder (RDA), and common losses of C4H10, CO, and CO2. The compounds in group B easily lose C6H12, forming a stable structure of a 1,4-dienyl group, unlike those in group A. The fragmentation pathway for group C is characterized by obvious 1,4A-, 1,4B- cracking of the C ring. The diagnostic fragmentation for group D is obvious RDA cracking of the C ring and the successive loss of CH3 and H2O in the LTQ-Orbitrap-MSn spectra. Fragmentation with successive loss of CO or CO2, ·CH3, and CH4 in the LTQ-Orbitrap-MSn spectra formed the characteristics of group E. The summarized fragmentation rules were successfully exploited to identify PFs from Artocarpus heterophyllus, a well-known Artocarpus plant, which led to the identification of a total of 47 PFs in this plant.

The Influence of 6-Prenylnaringenin and Selected Non-prenylated Flavonoids on the Activity of Kv1.3 Channels in Human Jurkat T Cells.

The influence of a prenylated flavonoid-6-prenylnaringenin (6-PR) and selected non-prenylated flavonoids: acacetin, chrysin, baicalein, wogonin, and luteolin on the activity of voltage-gated potassium channels Kv1.3 was investigated in human leukemic Jurkat T cells. Electrophysiological measurements were accompanied by studies on the cytotoxic effect of the examined compounds on Jurkat T cells. Electrophysiological studies were performed using the whole-cell patch-clamp technique. Cell viability was determined using the MTT assay. 6-PR inhibited Kv1.3 channels in Jurkat T cells in a concentration-dependent manner. The estimated value of the half-blocking concentration (EC50) was about 5.76 µM. Among non-prenylated flavonoids, acacetin and chrysin inhibited Kv1.3 channels in Jurkat T cells when applied at the concentration of 30 µM, whereas baicalein, wogonin, and luteolin were ineffective at this concentration. The inhibitory effects of acacetin and chrysin on Kv1.3 channels were significantly less potent than the inhibition caused by 6-PR. All tested compounds inhibited growth of Jurkat T cells in a concentration-dependent manner. Wogonin and chrysin were the most cytotoxic flavonoids tested, whereas baicalein and 6-PR were the least cytotoxic compounds. In accordance to our hypothesis the prenylated flavonoid (6-PR) was much more effective inhibitor of Kv1.3 channels than non-prenylated compounds selected for this study. The inhibition of Kv1.3 channels by 6-PR, acacetin, and chrysin was not related to cytotoxicity of these compounds. The channels' inhibition might be involved in anti-proliferative and pro-apoptotic effects of 6-PR, acacetin and chrysin observed in cancer cell lines expressing these channels.

Prenylated Flavonoids from Roots of Glycyrrhiza uralensis Induce Differentiation of B16-F10 Melanoma Cells.

Roots of Glycyrrhiza uralensis have been used as herbal medicine and natural sweetener. By activity-guided phytochemical investigation of the extracts from G.uralensis root, ten flavonoids, namely GF-1⁻GF-10, of which five were prenylated flavonoids, were found to show antiproliferative effects in melanoma B16-F10 cells. Three of the prenylated flavonoids, namely GF-1, GF-4 and GF-9, significantly induced the differentiation of B16-F10 cells; the inductions included increase of tyrosinase activity, tyrosinase protein, and melanin content. In GF-1 and GF-9 induced melanoma differentiation, the phosphorylation of p38 MAPK (mitogen activated potein kinase) was identified; while GF-4 could trigger the phosphorylation of PI3K/AKT (phosphatidylinositol 3-kinase/Protein Kinase B) signaling. However, application of GF-6 to the melanoma cells did not induce differentiation; but which promoted cell apoptotic signaling, i.e., increase levels of cleaved-PRAP, cleaved-caspase 3, and cleaved-caspase 9. These results suggested that different types of prenylated flavonoids from G.uralensis might have potential anticancer effects against melanoma cells by acting through different signaling pathways.

Anti-Inflammatory, Anti-Diabetic, and Anti-Alzheimer's Effects of Prenylated Flavonoids from Okinawa Propolis: An Investigation by Experimental and Computational Studies.

Okinawa propolis (OP) and its major ingredients were reported to have anti-cancer effects and lifespan-extending effects on Caenorhabditis elegans through inactivation of the oncogenic kinase, p21-activated kinase 1 (PAK1). Herein, five prenylated flavonoids from OP, nymphaeol-A (NA), nymphaeol-B (NB), nymphaeol-C (NC), isonymphaeol-B (INB), and 3'-geranyl-naringenin (GN), were evaluated for their anti-inflammatory, anti-diabetic, and anti-Alzheimer's effects using in vitro techniques. They showed significant anti-inflammatory effects through inhibition of albumin denaturation (half maximal inhibitory concentration (IC50) values of 0.26⁻1.02 µM), nitrite accumulation (IC50 values of 2.4⁻7.0 µM), and cyclooxygenase-2 (COX-2) activity (IC50 values of 11.74⁻24.03 µM). They also strongly suppressed in vitro α-glucosidase enzyme activity with IC50 values of 3.77⁻5.66 µM. However, only INB and NA inhibited acetylcholinesterase significantly compared to the standard drug donepezil, with IC50 values of 7.23 and 7.77 µM, respectively. Molecular docking results indicated that OP compounds have good binding affinity to the α-glucosidase and acetylcholinesterase proteins, making non-bonded interactions with their active residues and surrounding allosteric residues. In addition, none of the compounds violated Lipinski's rule of five and showed notable toxicity parameters. Density functional theory (DFT)-based global reactivity descriptors demonstrated their high reactive nature along with the kinetic stability. In conclusion, this combined study suggests that OP components might be beneficial in the treatment of inflammation, type 2 diabetes mellitus, and Alzheimer's disease.