Antibacterial effects of afzelin isolated from Cornus macrophylla on Pseudomonas aeruginosa, a leading cause of illness in immunocompromised individuals

Antibacterial and Antioxidant Activities of Flavonoids, Phenolic and Flavonoid Glycosides from Gouania longispicata Leaves

The leaves of Gouania longispicata Engl. (GLE) have been traditionally used to treat more than forty ailments in Uganda, including stomachache, lung and skin cancers, syphilis, toothache, and allergies. In this study, pure compounds were isolated from the methanolic extract of GLE leaves and their structures elucidated using ultraviolet visible spectroscopy, liquid chromatography–tandem mass spectrometry, high performance liquid chromatography, and 1D and 2D NMR techniques. The antibacterial and antioxidant activities of the compounds were assessed using the broth dilution and DPPH assays, respectively. Two known flavonoid glycosides (kaempferol-3-O-α-rhamnopyranoside and rutin), a phenolic glycoside (4,6-dihydroxy-3-methylacetophenone-2-O-β-D-glucopyranoside), and flavonoids (kaempferol and quercetin) were characterized. This is the first time that the kaempferol derivative, the acetophenone as well as free forms of quercetin, kaempferol, and rutin, are being reported in GLE and the Gouania genus. The compounds exhibited antibacterial activity against Streptococcus pneumoniae and Escherichia coli with minimum inhibitory concentrations between 16 µg/mL and 125 µg/mL. The radical scavenging activities recorded half-minimum inhibitory concentrations (IC50) ranging from 18.6 ± 1.30 µg/mL to 28.1 ± 0.09 µg/mL. The IC50 of kaempferol and quercetin were not significantly different from that of ascorbic acid (p > 0.05), highlighting their potential as natural antioxidant agents. These results lend credence to the use of GLE leaves in herbal treatment of microbial infections and oxidative stress-mediated ailments.

Antibacterial Activity of Glycosylated Flavonoids Isolated from Ocotea notata Leaves

Research into natural products has led to the discovery of new drugs. This work shows relevant data on the antibacterial activity of Ocotea notata leaves. Dichloromethane fraction (DF) from leaves of O. notata showed antibacterial activity at the concentration of 512 μg/mL against strains of Staphylococcus. The DF was fractionated to investigate bioactive compounds and yielded six subfractions (DF1-DF6). The DF3, DF5, and DF6 showed bacteriostatic activity, and DF4 showed bactericidal activity at the concentration of 2048 μg/mL and additive effect when combined with the antibiotic oxacillin. The flavonoids miquelianin (1), isoquercitrin (2), reynoutrin (3), guaijaverin (4), and afzelin (5) were isolated from the DF4 and characterized via NMR and HPLC-DAD-MS/MS analyses. Flavonoids 1-5, especially reynoutrin (3), seem to be responsible for the DF4 antibacterial activity. Reynoutrin showed activity against Staphylococcus epidermidis ATCC 12228 and S. aureus methicillin-resistant ATCC 33591. This is the first report regarding the reynoutrin antibacterial activity and the first description of the flavonoid guaijaverin for O. notata.

α-Glucosidase inhibitory flavonol glycosides from Cyclocarya paliurus (Batalin) Iljinskaja and their kinetics characteristics

Seven previously undescribed flavonol glycosides including four rare flavonol glycoside cyclodimers, dicyclopaliosides A-C (1-3) with truxinate type and dicyclopalioside D (4) with truxillate type, as well as three kaempferol glycoside derivatives cyclopaliosides A-C (5-7), were obtained from the leaves of Cyclocarya paliurus. Their structures were elucidated by extensive spectroscopic methods and chemical analyses. All compounds were evaluated for their inhibitory α-glucosidase activities. Among them, compounds 1-4 display strong inhibitory activities with IC50 values of 82.76 ± 1.41, 62.70 ± 4.00, 443.35 ± 16.48, and 6.31 ± 0.88 nM, respectively, while compounds 5-7 showed moderate activities with IC50 values of 4.91 ± 0.75, 3.64 ± 0.68, and 5.32 ± 0.53 μΜ, respectively. The structure-activity relationship analysis assumed that the cyclobutane cores likely contribute to the enhancement of α-glucosidase inhibitory activities of dimers. Also, the interaction mechanism between flavonol glycoside dimers and α-glucosidase were explored by the enzyme kinetic assay, indicating that compounds 1-3 exhibited mixed-type inhibition, while 4 showed uncompetitive inhibition. Additionally, the active compounds have also undergone molecular docking evaluation.

Effects of kaempherol-3-rhamnoside on metabolic enzymes and AMPK in the liver tissue of STZ-induced diabetes in mice

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by persistent hyperglycemia. It involves disturbances in carbohydrate, fat, and protein metabolism due to defects in insulin secretion, insulin action, or both. Novel therapeutic approaches are continuously being explored to enhance metabolic control and prevent complications associated with the disease. This study investigates the therapeutic potential of kaempherol-3-rhamnoside, a flavonoid, in managing diabetes by modulating the AMP-activated protein kinase (AMPK) pathway and improving metabolic enzyme activities in streptozotocin (STZ) -induced diabetic mice. Diabetic mice were treated with varying doses of kaempherol-3-rhamnoside and/or insulin over a 28-day period. Glycolytic and gluconeogenesis enzyme activities in the liver, fasting blood glucose levels, serum insulin levels, lipid profiles and oxidative stress markers were assessed. Treatment with kaempherol-3-rhamnoside significantly improved glycolytic enzyme activities, reduced fasting blood glucose, and enhanced insulin levels compared to diabetic controls. The compound also normalized lipid profiles and reduced oxidative stress in the liver, suggesting its potential in reversing diabetic dyslipidemia and oxidative damage. Furthermore, kaempherol-3-rhamnoside activated the AMPK pathway, indicating a mechanism through which it could exert its effects. Kaempherol-3-rhamnoside exhibits promising antidiabetic properties, potentially through AMPK pathway activation and metabolic enzyme modulation. These findings support its potential use as an adjunct therapy for diabetes management. Further clinical studies are warranted to validate these results in human subjects.

Flavonoid Composition and Antioxidant Activity of Tragia volubilis L. Methanolic Extract

Several species from the genus Tragia L. in the family Euphorbiaceae are part of the ethnomedicine of traditional cultures, and have a variety of uses. Tragia volubilis L. is a species spread through tropical America and Africa with several ethnomedical uses, particularly for wound healing and reproductive issues. In this study, we assess the phytochemical composition and antioxidant activity of the methanolic extract of the aerial parts of T. volubilis collected in southern Ecuador. The phytochemical screening of the extract shows the preliminary presence of carbohydrates, alkaloids, flavonoids, and tannins. The extract shows an Antioxidant Activity Index of 1.14, interpreted as strong antioxidant activity. Four flavonoid compounds were isolated through chromatographic procedures and identified through NMR spectroscopy: avicularin, quercitrin, afzelin, and amentoflavone. The biological activity of these compounds matches the ethnopharmacological uses of the species. This is the first phytochemical study of T. volubilis and supports its traditional medicinal uses.

Metabolic profiling of Chimonanthus grammatus via UHPLC-HRMS-MS with computer-assisted structure elucidation and its antimicrobial activity

Chimonanthus grammatus is used as Hakka traditional herb to treat cold, flu, etc. So far, the phytochemistry and antimicrobial compounds have not been well investigated. In this study, the orbitrap-ion trap MS was used to characterize its metabolites, combined with a computer-assisted structure elucidation method, and the antimicrobial activities were assessed by a broth dilution method against 21 human pathogens, as well as the bioassay-guided purification work to clarify its main antimicrobial compounds. A total of 83 compounds were identified with their fragmentation patterns, including terpenoids, coumarins, flavonoids, organic acids, alkaloids, and others. The plant extracts can strongly inhibit the growth of three Gram-positive and four Gram-negative bacteria, and nine active compounds were bioassay-guided isolated, including homalomenol C, jasmonic acid, isofraxidin, quercitrin, stigmasta-7,22-diene-3β,5α,6α-triol, quercetin, 4-hydroxy-1,10-secocadin-5-ene-1,10-dione, kaempferol, and E-4-(4,8-dimethylnona-3,7-dienyl)furan-2(5H)-one. Among them, isofraxidin, kaempferol, and quercitrin showed significant activity against planktonic Staphylococcus aureus (IC50 = 13.51, 18.08 and 15.86 µg/ml). Moreover, their antibiofilm activities of S. aureus (BIC50 = 15.43, 17.31, 18.86 µg/ml; BEC50 = 45.86, ≥62.50, and 57.62 µg/ml) are higher than ciprofloxacin. The results demonstrated that the isolated antimicrobial compounds played the key role of this herb in combating microbes and provided benefits for its development and quality control, and the computer-assisted structure elucidation method was a powerful tool for chemical analysis, especially for distinguishing isomers with similar structures, which can be used for other complex samples.

Loranthus tanakae Franch. & Sav. Suppresses Inflammatory Response in Cigarette Smoke Condensate Exposed Bronchial Epithelial Cells and Mice

Loranthus tanakae Franch. & Sav. found in China, Japan, and Korea is traditionally used for managing arthritis and respiratory diseases. In this study, we analyzed the components of L. tanakae 70% ethanol extract (LTE) and investigated the therapeutic effects of LTE on pulmonary inflammation using cells exposed to cigarette smoke condensate (CSC) and lipopolysaccharide (LPS) in vitro and in vivo in mice and performed a network analysis between components and genes based on a public database. We detected quercitrin, afzelin, rhamnetin 3-rhamnoside, and rhamnocitrin 3-rhamnoside in LTE, which induced a significant reduction in inflammatory mediators including interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α and inflammatory cells in CSC exposed H292 cells and in mice, accompanied by a reduction in inflammatory cell infiltration into lung tissue. In addition, LTE increased translocation into the nuclei of nuclear factor erythroid-2-related factor 2 (Nrf2). By contrast, the activation of nuclear factor (NF)-κB, induced by CSC exposure, decreased after LTE application. These results were consistent with the network pharmacological analysis. In conclusion, LTE effectively attenuated pulmonary inflammation caused by CSC+LPS exposure, which was closely involved in the enhancement of Nrf2 expression and suppression of NF-κB activation. Therefore, LTE may be a potential treatment option for pulmonary inflammatory diseases including chronic obstructive pulmonary disease (COPD).

Insights into the Antibacterial Activity of Prolactin-Inducible Protein against the Standard and Environmental MDR Bacterial Strains

Background: Prolactin inducible protein (PIP) is a small secretary glycoprotein present in most biological fluids and contributes to various cellular functions, including cell growth, fertility, antitumor, and antifungal activities. Objectives: The present study evaluated the antibacterial activities of recombinant PIP against multiple broad-spectrum MDR bacterial strains. Methods: The PIP gene was cloned, expressed and purified using affinity chromatography. Disk diffusion, broth microdilution, and growth kinetic assays were used to determine the antibacterial activities of PIP. Results: Disk diffusion assay showed that PIP has a minimum and maximum zone of inhibition against E. coli and P. aeruginosa, respectively, compared to the reference drug ampicillin. Furthermore, growth kinetics studies also suggested that PIP significantly inhibited the growth of E. coli and P. aeruginosa. The minimum inhibitory concentration of PIP was 32 µg/mL for E. coli (443), a standard bacterial strain, and 64 µg/mL for Bacillus sp. (LG1), an environmental multidrug-resistant (MDR) strain. The synergistic studies of PIP with ampicillin showed better efficacies towards selected bacterial strains having MDR properties. Conclusion: Our findings suggest that PIP has a broad range of antibacterial activities with important implications in alleviating MDR problems.

Kaempferol 3-Rhamnoside on Glutamate Release from Rat Cerebrocortical Nerve Terminals Involves P/Q-Type Ca2+ Channel and Ca2+/Calmodulin-Dependent Protein Kinase II-Dependent Pathway Suppression

Excess synaptic glutamate release has pathological consequences, and the inhibition of glutamate release is crucial for neuroprotection. Kaempferol 3-rhamnoside (KR) is a flavonoid isolated from Schima superba with neuroprotective properties, and its effecton the release of glutamate from rat cerebrocortical nerve terminals was investigated. KR produced a concentration-dependent inhibition of 4-aminopyridine (4-AP)-evoked glutamate release with half-maximal inhibitory concentration value of 17 µM. The inhibition of glutamate release by KR was completely abolished by the omission of external Ca²⁺ or the depletion of glutamate in synaptic vesicles, and it was unaffected by blocking carrier-mediated release. In addition, KR reduced the 4-AP-evoked increase in Ca²⁺ concentration, while it did not affect 4-AP-evoked membrane potential depolarization. The application of selective antagonists of voltage-dependent Ca²⁺ channels revealed that the KR-mediated inhibition of glutamate release involved the suppression of P/Q-type Ca²⁺ channel activity. Furthermore, the inhibition of release was abolished by the calmodulin antagonist, W7, and Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) inhibitor, KN62, but not by the protein kinase A (PKA) inhibitor, H89, or the protein kinase C (PKC) inhibitor, GF109203X. We also found that KR reduced the 4-AP-induced increase in phosphorylation of CaMKII and its substrate synapsin I. Thus, the effect of KR on evoked glutamate release is likely linked to a decrease in P/Q-type Ca²⁺ channel activity, as well as to the consequent reduction in the CaMKII/synapsin I pathway.

Digalloyl Glycoside: A Potential Inhibitor of Trypanosomal PFK from Euphorbia abyssinica J.F. Gmel

Human African trypanosomiasis is an endemic infectious disease caused by Trypanosoma brucei via the bite of tsetse-fly. Most of the drugs used for the treatment, e.g., Suramin, have shown several problems, including the high level of toxicity. Accordingly, the discovery of anti-trypanosomal drugs from natural sources has become an urgent requirement. In our previous study on the anti-trypanosomal potential of Euphorbia species, Euphorbia abyssinica displayed significant anti-trypanosomal activity. Therefore, a phytochemical investigation of the methanolic extract of E. abyssinica was carried out. Twelve compounds, including two triterpenes (1, 2); one sterol-glucoside (4); three ellagic acid derivatives (3, 9, 11); three gallic acid derivatives (5, 6, 10); and three flavonoids (7, 8, 12), were isolated. The structures of isolated compounds were determined through different spectroscopic techniques. Compound (10) was obtained for the first time from genus Euphorbia while all other compounds except compound (4), were firstly reported in E. abyssinica. Consequently, an in silico study was used to estimate the anti-trypanosomal activity of the isolated compounds. Several compounds displayed interesting activity where 1,6-di-O-galloyl-d-glucose (10) appeared as the most potent inhibitor of trypanosomal phosphofructokinase (PFK). Moreover, molecular dynamics (MD) simulations and ADMET calculations were performed for 1,6-di-O-galloyl-d-glucose. In conclusion, 1,6-di-O-galloyl-d-glucose revealed high binding free energy as well as desirable molecular dynamics and pharmacokinetic properties; therefore, it could be suggested for further in vitro and in vivo studies for trypanosomiasis.

Plant-Derived Compounds as Promising Therapeutics for Vitiligo

Vitiligo is the most common depigmenting disorder characterized by white patches in the skin. The pathogenetic origin of vitiligo revolves around autoimmune destruction of melanocytes in which, for instance, oxidative stress is responsible for melanocyte molecular, organelle dysfunction and melanocyte specific antigen exposure as well as melanocyte cell death and thus serves as an important contributor for vitiligo progression. In recent years, natural products have shown a wide range of pharmacological bioactivities against many skin diseases, and this review focuses on the effects and mechanisms of natural compounds against vitiligo models. It is showed that some natural compounds such as flavonoids, phenols, glycosides and coumarins have a protective role in melanocytes and thereby arrest the depigmentation, and, additionally, Nrf2/HO-1, MAPK, JAK/STAT, cAMP/PKA, and Wnt/β-catenin signaling pathways were reported to be implicated in these protective effects. This review discusses the great potential of plant derived natural products as anti-vitiligo agents, as well as the future directions to explore.

Novel dTDP-l-Rhamnose Synthetic Enzymes (RmlABCD) From Saccharothrix syringae CGMCC 4.1716 for One-Pot Four-Enzyme Synthesis of dTDP-l-Rhamnose

Deoxythymidine diphospho-l-rhamnose (dTDP-l-rhamnose) is used by prokaryotic rhamnosyltransferases as the glycosyl donor for the synthesis of rhamnose-containing polysaccharides and compounds that have potential in pharmaceutical development, so its efficient synthesis has attracted much attention. In this study, we successfully cloned four putative dTDP-l-rhamnose synthesis genes Ss-rmlABCD from Saccharothrix syringae CGMCC 4.1716 and expressed them in Escherichia coli. The recombinant enzymes, Ss-RmlA (glucose-1-phosphate thymidylyltransferase), Ss-RmlB (dTDP-d-glucose 4,6-dehydratase), Ss-RmlC (dTDP-4-keto-6-deoxy-glucose 3,5-epimerase), and Ss-RmlD (dTDP-4-keto-rhamnose reductase), were confirmed to catalyze the sequential formation of dTDP-l-rhamnose from deoxythymidine triphosphate (dTTP) and glucose-1-phosphate (Glc-1-P). Ss-RmlA showed maximal enzyme activity at 37°C and pH 9.0 with 2.5mMMg2+, and the K m and k cat values for dTTP and Glc-1-P were 49.56μM and 5.39s-1, and 117.30μM and 3.46s-1, respectively. Ss-RmlA was promiscuous in the substrate choice and it could use three nucleoside triphosphates (dTTP, dUTP, and UTP) and three sugar-1-Ps (Glc-1-P, GlcNH2-1-P, and GlcN3-1-P) to form nine sugar nucleotides (dTDP-GlcNH2, dTDP-GlcN3, UDP-Glc, UDP-GlcNH2, UDP-GlcN3, dUDP-Glc, dUDP-GlcNH2, and dUDP-GlcN3). Ss-RmlB showed maximal enzyme activity at 50°C and pH 7.5 with 0.02mM NAD+, and the K m and k cat values for dTDP-glucose were 98.60μM and 11.2s-1, respectively. A one-pot four-enzyme reaction system was developed by simultaneously mixing all of the substrates, reagents, and four enzymes Ss-RmlABCD in one pot for the synthesis of dTDP-l-rhamnose and dUDP-l-rhamnose with the maximal yield of 65% and 46%, respectively, under the optimal conditions. dUDP-l-rhamnose was a novel nucleotide-activated rhamnose reported for the first time.

Concurrent Pseudomonas Periorbital Necrotizing Fasciitis and Endophthalmitis: A Case Report and Literature Review

(1) Background: Necrotizing fasciitis (NF) is an infection involving the superficial fascia and subcutaneous tissue. Endophthalmitis is an infection within the ocular ball. Herein we report a rare case of concurrent periorbital NF and endophthalmitis, caused by Pseudomonas aeruginosa (PA). We also conducted a literature review related to periorbital PA skin and soft-tissue infections. (2) Case presentation: A 62-year-old male had left upper eyelid swelling and redness; orbital cellulitis was diagnosed. During eyelid debridement, NF with the involvement of the upper Müller’s muscle and levator muscle was noted. The infection soon progressed to scleral ulcers and endophthalmitis. The eye developed phthisis bulbi, despite treatment with intravitreal antibiotics. (3) Conclusions: Immunocompromised individuals are more likely than immunocompetent hosts to be infected by PA. Although periorbital NF is uncommon due to the rich blood supply in the area, the possibility of PA infection should be considered in concurrent periorbital soft-tissue infection and endophthalmitis.

Characterization of bitter compounds in native and hybrid American hazelnuts

The main objective of this study was to identify compounds that contribute to the bitter taste attributes of American hazelnuts (C. americana) and derived hybrids. Sensory-guided Prep-LC fractionation analysis selected four compounds as bitter that were further identified by MS and NMR as carpinontriol B, 2-(3-hydroxy-2-oxoindolin-3-yl)acetic acid 3-O-6'-galactopyranosyl-2″-(2″oxoindolin-3″yl) acetate, giffonin-2-O-[(α-d-glucopyranosyl)-6'-O-(3-hydroxy-3-methylglutaric acid) and Afzelin, termed compounds 1-4, respectively. The concentrations of compounds 1, 2, 3, and 4 were determined across 88 American hybrid hazelnut genotypes and reported to be present at levels above their bitter threshold values in 94, 75, 25, and 0% of the samples, respectively. Moreover, the concentrations of compounds 1 and 3 were significantly higher for nuts dehusked prior to drying during post-harvest handling, which is expected to result in a higher perceived bitter intensity.

Central administration of afzelin extracted from Ribes fasciculatum improves cognitive and memory function in a mouse model of dementia

Neurodegenerative disorders are characterized by the decline of cognitive function and the progressive loss of memory. The dysfunctions of the cognitive and memory system are closely related to the decreases in brain-derived neurotrophic factor (BDNF) and cAMP response element-binding protein (CREB) signalings. Ribes fasciculatum, a medicinal plant grown in diverse countries, has been reported to pharmacological effects for autoimmune diseases and aging recently. Here we found that afzelin is a major compound in Ribes fasciculatum. To further examine its neuroprotective effect, the afzelin (100 ng/µl, three times a week) was administered into the third ventricle of the hypothalamus of C57BL/6 mice for one month and scopolamine was injected (i.p.) to these mice to impair cognition and memory before each behavior experiment. The electrophysiology to measure long-term potentiation and behavior tests for cognitive and memory functions were performed followed by investigating related molecular signaling pathways. Chronic administration of afzelin into the brain ameliorated synaptic plasticity and cognitive/memory behaviors in mice given scopolamine. Studies of mice's hippocampi revealed that the response of afzelin was accountable for the restoration of the cholinergic systems and molecular signal transduction via CREB-BDNF pathways. In conclusion, the central administration of afzelin leads to improved neurocognitive and neuroprotective effects on synaptic plasticity and behaviors partly through the increase in CREB-BDNF signaling.

Cornus macrophylla, the Antibacterial Activity of Organic Leaf Extracts and the Characterization of the More Lipophilic Components by GC/MS

In the present study, the antibacterial activity of Cornus macrophylla was examined. Organic solvent extracts of leaves were prepared using methanol, n-hexane, chloroform, and ethyl acetate. Antibacterial activity was examined by using a 100 mg/mL extract concentration. Penicillin was kept as a positive control while dimethyl sulfoxide was taken as a negative control. Methanolic extract exhibited a 21.5, 36.3, 25.3, and 23.7 mm inhibition zone diameter (IZD); n-hexane showed a 33, 40, 32.8, and 28.7 mm IZD; chloroform showed a 18.8, 29, 22.3, and 21.6 mm IZD; and ethyl acetate showed a 23.5, 30.2, 30, and 22.3 mm IZD against Erwinia carotovora, Pseudomonas syringae, Ralstonia solanacearum, and Xanthomonas axonopodis, respectively. The n-hexane extract revealed high antibacterial activity against all bacterial species as compared with methanolic, chloroform, and ethyl acetate extract. Gas Chromatography Mass Spectrometry (GC/MS) analysis of n-hexane extract depicted the presence of 55 compounds. Out of these compounds, one compound, identified as α-amyrin (Mol. wt = 426), exhibited the maximum peak area (32.64%), followed by A'-Neogammacer-22(29)-en-3-ol, acetate, (3.beta.,21.beta.)- (Mol. wt = 468) and β-amyrin (Mol. wt = 426) having peak areas of 25.97 and 6.77%, respectively. It was concluded that the antibacterial activity observed during the present investigation may be due to these compounds.

Flavonoid Glycosides from Heracleum pastinaca Fenzl

OBJECTIVES

The objective was to isolate and characterize the secondary metabolites of Heracleum pastinaca, which has not been previously investigated.

MATERIALS AND METHODS

Conventional chromatographic procedures were carried out for isolation of the compounds. The structures of the compounds were elucidated by extensive 1D and 2D nuclear magnetic resonance spectroscopic analysis in combination with mass spectrometry experiments and comparison with the relevant literature data.

RESULTS

This first phytochemical investigation on all parts of H. pastinaca Fenzl led to the isolation and identification of seven known flavonoid glycosides: isoquercetin (1), rutin (2), afzelin (3), astragalin (4), isorhamnetin 3-O-glucoside (5), nicotiflorin (6), and narcissoside (7).

CONCLUSION

This is the first report on the isolation of these flavonoid glycosides from H. pastinaca and compounds 3, 5, 6, and 7 from the genus Heracleum.

Afzelin suppresses proinflammatory responses in particulate matter-exposed human keratinocytes

Particulate matter (PM), a widespread airborne contaminant, is a complex mixture of solid and liquid particles suspended in the air. Recent studies have demonstrated that PM induces oxidative stress and inflammatory reactions, and may cause certain skin diseases. Afzelin is a flavonoid isolated from Thesium chinense Turcz, which has anti‑inflammatory, anticancer and antibacterial properties. Therefore, the present study aimed to investigate if afzelin affected inflammatory responses in human keratinocytes exposed to PM. HaCaT cells were treated with PM (25 µg/cm2) in the presence or absence of afzelin (200 µM). Here, standard reference material 1649b was used as PM. Cell viability was assessed using the water‑soluble tetrazolium salt‑1 assay. The generation of reactive oxygen species (ROS) was measured using the dichloro‑dihydro‑​fluorescein diacetate assay. Gene and protein expression were investigated using reverse transcription‑quantitative polymerase chain reaction and western blot analysis, respectively. Levels of secreted inflammatory cytokines were measured using ELISA. The results suggested that afzelin inhibited PM‑induced proinflammatory cytokine mRNA expression and protein secretion in HaCaT cells. In addition, afzelin suppressed PM‑induced intracellular ROS generation, and p38 mitogen‑activated protein kinase and transcription factor activator protein‑1 component c‑Fos and c‑Jun activation. The results indicated that afzelin exerts anti‑inflammatory and antioxidant effects in PM‑exposed HaCaT. Afzelin may have potential for preventing PM‑induced inflammatory skin diseases.

Effects of Toona sinensis Leaf Extract and Its Chemical Constituents on Xanthine Oxidase Activity and Serum Uric Acid Levels in Potassium Oxonate-Induced Hyperuricemic Rats

Toona sinensis leaf is used as a seasonal vegetable in Korea. A 70% ethanol extract of these leaves exhibited potent xanthine oxidase (XO) inhibition, with a 50% inhibitory concentration (IC₅₀) of 78.4 µM. To investigate the compounds responsible for this effect, bioassay-guided purification led to the isolation of five constituents, identified as quercetin-3-O-rutinoside, quercetin-3-O-β-d-glucopyranoside, 1,2,3,4,6-penta-O-galloyl-β-d-glucopyranose (compound 3), quercetin-3-O-α-l-rhamnopyranoside, and kaempferol-3-O-α-l-rhamnopyranoside. Compound 3 showed the most potent inhibition of XO, with an IC₅₀ of 2.8 µM. This was similar to that of allopurinol (IC₅₀ = 2.3 µM), which is used clinically to treat hyperuricemia. Kinetic analyses found that compound 3 was a reversible noncompetitive XO inhibitor. In vivo, the T. sinensis leaf extract (300 mg/kg), or compound 3 (40 mg/kg), significantly decreased serum uric acid levels in rats with potassium oxonate-induced hyperuricemia. Furthermore, ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry analysis identified a high level of compound 3 in the leaf extract. These findings suggest that T. sinensis leaves could be developed to produce nutraceutical preparations.

Deep eutectic solvents used as extraction solvent for the determination of flavonoids from Camellia oleifera flowers by high-performance liquid chromatography

INTRODUCTION

Camellia oleifera flowers are rich in flavonoids, but there has been little attention on their application. A simple and reliable method for determining the content of flavonoids in C. oleifera flowers would be very helpful for the utilisation of agriculture resources.

OBJECTIVE

To develop an efficient analytical method for the determination of flavonoids in C. oleifera flowers by high-performance liquid chromatography-ultraviolet (HPLC-UV) detection.

METHODOLOGY

Preparing an environmentally-friendly and effective solvent - deep eutectic solvents (DESs) - for compound extraction. Then investigating the influential factors of ultrasound-assisted extraction with DESs by the Box-Behnken design combined with response surface methodology.

RESULTS

DES-5 synthesised with choline chloride and lactic acid (1:2) acquired excellent extractability for four flavonoids (quercetin 3-O-rhamnoside, kaempferol 3-O-rhamnoside and their aglycones) with different polarity. The proposed method, which could simultaneously determine four flavonoids with HPLC-UV detection for the first time, displays satisfactory recovery yields and high precision with inter-day relative standard deviation lower than 5.80%.

CONCLUSION

DESs could be promising solvents for efficiently and selectively extracting bioactive compounds from plant materials, and the analytical method for flavonoids of C. oleifera flowers could provide reference value for its application and be used in other plant resources.

A regiospecific rhamnosyltransferase from Epimedium pseudowushanense catalyzes the 3-O-rhamnosylation of prenylflavonols

A novel rhamnosyltransferase and a UDP-rhamnose synthase were characterized and applied to the biosynthesis of bioactive prenylflavonol rhamnosides.

Cannabidiol upregulates melanogenesis through CB1 dependent pathway by activating p38 MAPK and p42/44 MAPK

Melanogenesis plays a critical role in the protection of skin against external stresses such as ultraviolet irradiation and oxidative stressors. This study was aimed to investigate the effects of cannabidiol on melanogenesis and its mechanisms of action in human epidermal melanocytes. We found that cannabidiol increased both melanin content and tyrosinase activity. The mRNA levels of microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein (TRP) 1, and TRP2 were increased following cannabidiol treatment. Likewise, cannabidiol increased the protein levels of MITF, TRP 1, TRP 2, and tyrosinase. Mechanistically, we found that cannabidiol regulated melanogenesis by upregulating MITF through phosphorylation of p38 mitogen-activated protein kinase (MAPK) and p42/44 MAPK, independent of cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) signaling. In addition, the melanogenic effect of cannabidiol was found to be mediated by cannabinoid CB₁ receptor, not by CB₂ receptor. Taken together, these findings indicate that cannabidiol-induced melanogenesis is cannabinoid CB₁ receptor-dependent, and cannabidiol induces melanogenesis through increasing MITF gene expression which is mediated by activation of p38 MAPK and p42/44 MAPK. Our results suggest that cannabidiol might be useful as a protective agent against external stresses.

Melanocyte-protective effect of afzelin is mediated by the Nrf2-ARE signalling pathway via GSK-3β inactivation

Vitiligo is an acquired condition characterized by depigmented, cutaneous lesions that result from the death of pigment-producing cells, melanocytes. The occurrence of oxidative stress has been proposed as a pathogenetic mechanism for melanocyte degeneration in vitiligo. Therefore, in this study, we investigated the cytoprotective effects of afzelin against oxidative stress and its mechanism of action in human epidermal melanocytes. We found that afzelin significantly inhibited hydrogen peroxide-induced cell death, cellular reactive oxygen species production and lipid peroxidation in melanocytes. In an antioxidant response element (ARE)-luciferase reporter assay, afzelin increased ARE-luciferase reporter activity in a concentration-dependent manner. Consistently, the expression of antioxidant genes, including NF-E2-related factor 2 (Nrf2), haem oxygenase-1 (HO-1) and catalase, was enhanced by afzelin treatment. Nuclear translocation of Nrf2 also increased in response to afzelin treatment. In addition, the phosphorylation of glycogen synthase kinase-3β (GSK-3β) was induced by afzelin treatment. The enhancement of HO-1 gene expression by afzelin treatment was reduced by Nrf2-siRNA expression. Furthermore, we found that the expression of Nrf2-siRNA significantly attenuated the cytoprotective effect of afzelin against hydrogen peroxide. These data suggest that the cytoprotective effects of afzelin against hydrogen peroxide may be mediated by Nrf2-ARE signalling via GSK-3β inactivation. Our data suggest the novel use of afzelin for the prevention of oxidative stress-induced damage in melanocytes and its potential as a therapeutic agent for vitiligo.

Chemical Composition and Antioxidant Activity of Cirsium vulgare Inflorescences

The chemical composition of Cirsium vulgare flower heads was examined. Petrol and chloroform extracts of this plant material were analyzed by GC-MS for the presence of fatty acids, phytosterols, and triterpenes. Diethyl ether, ethyl acetate, and butanol fractions of the methanolic extract were subjected to multistep chromatographic separations, and as a result, fourteen flavonoids were obtained (1–14). All compounds were isolated from this morphological part for the first time and eleven from the plant. Among the identified components were four aglycones, eight glycosides, and two glycoside esters, derivatives of apigenin, luteolin, kaemferol, and quercetin. One of them was a rarely occurring compound apigenin 7- O-β-(6″-butyl)-glucuronide) (14). Total flavonoid content and antioxidant activity were determined in the various fractions of methanolic extract.

Antibacterial activities of the methanol extract, fractions and compounds from Elaeophorbia drupifera (Thonn.) Stapf. (Euphorbiaceae)

Background

Elaeophorbia drupifera (Thonn.) Stapf. (Euphorbiaceae) is used in Cameroonian folk medicine to treat several ailments including bacterial-related diseases such as skin infections. In this study, the methanol extract from the leaves (EDL), fractions (EDLa-d), sub-fractions EDLc1-7 and EDLc31-35 as well as isolated compounds were tested for their antimicrobial activities against a panel of Gram-negative and Gram-positive bacteria including multidrug resistant (MDR) phenotypes.

Methods

The broth microdilution method was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the above samples; column chromatography was used for the fractionation and purification of the leaves extract whilst the chemical structures of compounds were determined using spectroscopic techniques.

Results

Phytochemical investigation lead to the isolation of a mixture (1:3) of stigmasterol and β-sitosterol (1 + 2), euphol (3), sitosterol-O-β-_D-xylopyranoside (4), 3,3′,4′-tri-O-methylellagic acid (5), a mixture (1:1) of afzelin and quercetin-3-O-β-_D-xylopyranoside (6 + 7), 3,3′,4′-tri-O-methylellagic acid 4-O-β-_D-glucopyranoside (8), ellagic acid-4-O-β-xylopyranoside-3,3′,4′-trimethyl ether (9) from EDLc. Crude extract and fractions displayed selective activities with MIC values ranged from 32 to 1024 μg/mL for EDL against 84.9% of the 33 tested bacteria, 93.9% for EDLc, 69.7% for EDLb, 33.4% for EDLa and 0.03% for EDLd. MIC values ranged from 16 to 1024 μg/mL were obtained with EDLc3 and EDLc4 on all tested bacteria meanwhile other sub-fractions displayed selective activities. MIC value of 32 μg/mL was obtained with fractions EDLa against Escherichia coli AG100, EDLc against Enterobacer aerogenes ATCC13048 and EA298. For sub-fractions obtained from EDLc, the lowest MIC value of 16 μg/mL was recorded with EDLc3 against Staphylococcus aureus MRSA11. A corresponding value of 8 μg/mL against Providencia stuartii NAE16 was recorded with EDLc33 obtained from further fractionation of EDLc3. EDLc3 had MIC values below 100 μg/mL against all tested bacteria. Compound 5 as well as the mixture (1:1) of 6 and 7 inhibited the growth of all the tested bacteria with MICs ranged from 64 to 256 μg/mL.

Conclusion

Elaeophorbia drupifera is a potential source of phytomedicine to tackle MDR bacteria. Sub-fraction EDLc3 was more active than all isolated compounds and deserves further investigations to develop natural drug to combat Gram-negative, Gram-positive bacteria and otherwise MDR phenotypes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1509-y) contains supplementary material, which is available to authorized users.

Afzelin ameliorates D-galactosamine and lipopolysaccharide-induced fulminant hepatic failure by modulating mitochondrial quality control and dynamics

BACKGROUND AND PURPOSE

Fulminant hepatic failure (FHF) is a fatal clinical syndrome that results in excessive inflammation and hepatocyte death. Mitochondrial dysfunction is considered to be a possible mechanism of FHF. Afzelin, a flavonol glycoside found in Houttuynia cordata Thunberg, has anti-inflammatory and antioxidant properties. The present study elucidated the cytoprotective mechanisms of afzelin against D-galactosamine (GalN)/LPS induced FHF, particularly focusing on mitochondrial quality control and dynamics.

EXPERIMENTAL APPROACH

Mice were administered afzelin i.p. 1 h before receiving GalN (800 mg·kg^-1 )/LPS (40 μg·kg^-1 ), and they were then killed 5 h after GalN/LPS treatment.

KEY RESULTS

Afzelin improved the survival rate and reduced the serum levels of alanine aminotransferase and pro-inflammatory cytokines in GalN/LPS-treated mice. Afzelin attenuated the mitochondrial damage, as indicated by diminished mitochondrial swelling and mitochondrial glutamate dehydrogenase activity in GalN/LPS-treated mice. Afzelin enhanced mitochondrial biogenesis, as indicated by increased levels of PPAR-γ coactivator 1α, nuclear respiratory factor 1 and mitochondrial transcription factor A. Afzelin also decreased the level of mitophagy-related proteins, parkin and PTEN-induced putative kinase 1. Furthermore, while GalN/LPS significantly increased the level of fission-related protein, dynamin-related protein 1, and decreased the level of fusion-related protein, mitofusin 2; these effects were attenuated by afzelin.

CONCLUSIONS AND IMPLICATIONS

Our findings demonstrated that afzelin protects against GalN/LPS-induced liver injury by enhancing mitochondrial biogenesis, suppressing excessive mitophagy and balancing mitochondrial dynamics.

Chemical Constituents of Muehlenbeckia tamnifolia (Kunth) Meisn (Polygonaceae) and Its In Vitro α-Amilase and α-Glucosidase Inhibitory Activities

The phytochemical investigation of Muehlenbeckia tamnifolia, collected in Loja-Ecuador, led to the isolation of nine known compounds identified as: lupeol acetate (1); cis-p-coumaric acid (2); lupeol (3); β-sitosterol (4) trans-p-coumaric acid (5); linoleic acid (6) (+)-catechin (7); afzelin (8) and quercitrin (9). The structures of the isolated compounds were determined based on analysis of NMR and MS data, as well as comparison with the literature. The hypoglycemic activity of crude extracts and isolated compounds was assessed by the ability to inhibit α-amylase and α-glucosidase enzymes. The hexane extract showed weak inhibitory activity on α-amylase, with an IC₅₀ value of 625 µg·mL⁻¹, while the other extracts and isolated compounds were inactive at the maximum dose tested. The results on α-glucosidase showed more favorable effects; the hexanic and methanolic extracts exhibited a strong inhibitory activity with IC₅₀ values of 48.22 µg·mL⁻¹ and 19.22 µg·mL⁻¹, respectively. Four of the nine isolated compounds exhibited strong inhibitory activity with IC₅₀ values below 8 µM, much higher than acarbose (377 uM). Linoleic acid was the most potent compound (IC₅₀ = 0.42 µM) followed by afzelin, (+)-catechin and quercitrin.

Chemical constituents from Cordia alliodora and C. colloccoca (Boraginaceae) and their biological activities

Two new natural products, 5-O-[β-D-apiofuranosyl-(1→6)-β-d-glucopyranosyl]-1-isoindolinone (1) as well as N-(2E)-3-[(2S,3R)-2-(4-hydroxy-3-methoxyphenyl)-3-(hydroxymethyl)-7-methoxy-2,3-dihydro-1-benzofuran-5-yl]acryloylglycine (2), along with four known compounds (3-6), were isolated from the methanolic extract of Cordia alliodora root bark. Furthermore, the methanolic extract of Cordia colloccoca leaves, afforded the known flavonoids afzelin (7) and quercitrin (8). The isolated secondary metabolites were assayed for their antimicrobial activities against a panel of 6g positive and negative bacteria and three human pathogenic fungi. Moreover, their antiproliferative effect was also evaluated in vitro against the human non-small-cell bronchopulmonary carcinoma line NSCLC-N6, the epidermoid lung cancer cell line A549 as well as the normal human skin fibroblast cell line (AG01523).

Metabolite fingerprinting, pathway analyses, and bioactivity correlations for plant species belonging to the Cornaceae, Fabaceae, and Rosaceae families

A multi-parallel approach gauging the mass spectrometry-based metabolite fingerprinting coupled with bioactivity and pathway evaluations could serve as an efficacious tool for inferring plant taxonomic orders. Thirty-four species from three plant families, namely Cornaceae (7), Fabaceae (9), and Rosaceae (18) were subjected to metabolite profiling using gas chromatography-time-of-flight-mass spectrometry (GC-TOF-MS) and ultrahigh performance liquid chromatography-linear trap quadrupole-ion trap-mass spectrometry (UHPLC-LTQ-IT-MS/MS), followed by multivariate analyses to determine the metabolites characteristic of these families. The partial least squares discriminant analysis (PLS-DA) revealed the distinct clustering pattern of metabolites for each family. The pathway analysis further highlighted the relatively higher proportions of flavonols and ellagitannins in the Cornaceae family than in the other two families. Higher levels of phenolic acids and flavan-3-ols were observed among species from the Rosaceae family, while amino acids, flavones, and isoflavones were more abundant among the Fabaceae family members. The antioxidant activities of plant extracts were measured using ABTS, DPPH, and FRAP assays, and indicated that extracts from the Rosaceae family had the highest activity, followed by those from Cornaceae and Fabaceae. The correlation map analysis positively links the proportional concentration of metabolites with their relative antioxidant activities, particularly in Cornaceae and Rosaceae. This work highlights the pre-eminence of the multi-parallel approach involving metabolite profiling and bioactivity evaluations coupled with metabolic pathways as an efficient methodology for the evaluation of plant phylogenies.

Assessment of the antibacterial, cytotoxic and mutagenic potential of the phenolic-rich hydroalcoholic extract from Copaifera trapezifolia Hayne leaves

Copaifera trapezifolia Hayne occurs in the Atlantic Rainforest, which is considered one of the most important and endangered tropical forests on the planet. Although literature works have described many Copaifera spp., their biological activities remain little known. In the present study, we aimed to evaluate (1) the potential of the hydroalcoholic extract from C. trapezifolia leaves (CTE) to act against the causative agents of tooth decay and apical periodontitis and (2) the cytotoxicity and mutagenicity of CTE to ensure that it is safe for subsequent application. Concerning the tested bacteria, the MIC and the minimum bactericidal concentration of CTE varied between 100 and 400 µg ml-1. The time-kill assay conducted at a CTE concentration of 100 µg ml-1 evidenced bactericidal activity against Porphyromonas gingivalis (ATCC 33277) and Peptostreptococcus micros (clinical isolate) within 72 h. CTE at 200 µg ml-1 inhibited Porphyromonas gingivalis and Peptostreptococcus micros biofilm formation by at least 50 %. A combination of CTE with chlorhexidine dichlorohydrate did not prompt any synergistic effects. The colony-forming assay conducted on V79 cells showed that CTE was cytotoxic at concentrations above 156 µg ml-1. CTE exerted mutagenic effect on V79 cells, but the micronucleus test conducted on Swiss mice and the Ames test did not reveal any mutagenicity. Therefore, the use of standardized and safe extracts could be an important strategy to develop novel oral care products with antibacterial action. These extracts could also serve as a source of compounds for the discovery of new promising biomolecules.

Afzelin positively regulates melanogenesis through the p38 MAPK pathway

Melanogenesis refers to synthesis of the skin pigment melanin, which plays a critical role in the protection of skin against ultraviolet irradiation and oxidative stressors. We investigated the effects of afzelin on melanogenesis and its mechanisms of action in human epidermal melanocytes. In this study, we found that afzelin increased both melanin content and tyrosinase activity in a concentration-dependent manner. While the mRNA levels of microphthalmia-associated transcription factor (MITF), tyrosinase, and tyrosinase-related protein (TRP)-1 increased following afzelin treatment, the mRNA levels of TRP-2 were not affected by afzelin. Likewise, afzelin increased the protein levels of MITF, TRP-1, and tyrosinase but not TRP-2. Mechanistically, we found that afzelin regulated melanogenesis by upregulating MITF through phosphorylation of p38 mitogen-activated protein kinase (MAPK), independent of cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) signaling. Taken together, these findings indicate that the promotion of melanogenesis by afzelin occurs through increased MITF gene expression, which is mediated by activation of p38 MAPK, and suggest that afzelin may be useful as a protective agent against ultraviolet irradiation.

Therapeutic Potential of Polyphenols from Epilobium Angustifolium (Fireweed)

Epilobium angustifolium is a medicinal plant used around the world in traditional medicine for the treatment of many disorders and ailments. Experimental studies have demonstrated that Epilobium extracts possess a broad range of pharmacological and therapeutic effects, including antioxidant, anti-proliferative, anti-inflammatory, antibacterial, and anti-aging properties. Flavonoids and ellagitannins, such as oenothein B, are among the compounds considered to be the primary biologically active components in Epilobium extracts. In this review, we focus on the biological properties and the potential clinical usefulness of oenothein B, flavonoids, and other polyphenols derived from E. angustifolium. Understanding the biochemical properties and therapeutic effects of polyphenols present in E. angustifolium extracts will benefit further development of therapeutic treatments from this plant. Copyright © 2016 John Wiley & Sons, Ltd.

Phytochemical Profile of the Aerial Parts of Sedum sediforme and Anti-inflammatory Activity of Myricitrin

The aim of this study was to investigate the phytochemical profile of the methanol extract of the aerial parts of Sedum sediforme and to identify its secondary metabolites. By means of chromatographic separation and enrichment of compounds, HPLC-ESI-MS, HRMS, 1D-, 2D- NMR and/or comparison with reference compounds, three triterpenes, two sterols, ten flavonoids and twelve phenolic compounds were identified, together with two new compounds, i.e. (2 R*, 3 R*)-5,7-dihydroxy-2,3-dimethyl-4-chromanone-7- O-ß-D-glucoside (27) and butan-2- O-rutinoside (28). Out of the 29 identified secondary metabolites, 18 are described as ingredients of S. sediforme herein for the first time. Furthermore, myricitrin, one of the major constituents, was tested for its ability to inhibit different enzymes within the arachidonic acid cascade in order to determine its anti-inflammatory properties. Whereas there was only either weak or no inhibition of the microsomal prostaglandin E2 synthase-1 (mPGES-1) and the soluble epoxide hydrolase (sEH), myricitrin showed strong inhibition of 5-lipoxygenase (5-LO), with an IC50 of 7.8 ± 0.2 μM.