A dual antibacterial mechanism involved in membrane disruption and DNA binding of 2R,3R-dihydromyricetin from pine needles of Cedrus deodara against Staphylococcus aureus

Cedrus deodara (Roxb. ex D.Don) G.Don: A review of traditional use, phytochemical composition and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Cedrus deodara (Roxb. ex D.Don) G.Don (Family: Pinaceae) is a medicinal tree traditionally important and well mentioned in traditional system of medicine of India, Pakistan, China, Korea etc. for its use in the management of skin diseases, microbial infections, joint disorders, asthma, kidney stones, ulcer, brain disorders and immunological disorders.

AIM AND OBJECTIVES

This review provides an insight into the information available regarding traditional uses, ethnobotany, phytochemistry and, pharmacological profiling of C. deodara crude extract, its isolated compounds and, fractions, to explore its potential for the development of novel therapeutic agents.

MATERIAL AND METHODS

Various databases including Scopus, Google Scholar, Science Direct, ACS, Wiley, Web of Science, Springer Link and, PubMed were used to collect all the appropriate information available in previously published literature related to this plant. Besides, other official electronic sources viz. Encyclopedia Britannica and Northern Regional Center, Botanical Survey of India, theplantlist.org. and relevant book chapters and books were also explored.

RESULTS

C. deodara is a popular medicinally active tree, traditionally used in the form of decoction, syrup, oil, powder, and extract alone or in combination with other herbs for the management of different ailments viz. asthma, ulcers, bone fractures, sprains rheumatism, boils, leprosy, etc. Phytochemical studies reported 105 chemical constituents from different parts of the plant, most of them belong to a class of terpenoids and flavonoids. Crude extracts, essential oils, fractions, and isolated compounds of C. deodara exhibited some important pharmacological activities including anticancer, antimicrobial, antifungal, analgesic, anti-inflammatory, neuroprotective, antidiabetic, antiurolithiatic, antiarthritic and, antiasthmatic.

CONCLUSION

Present article delivers in-depth information on botany, ethnopharmacology, phytochemistry, pharmacology, and toxicology. C. deodara has been in practice among indigenous people of India, Pakistan, Nepal, Korea, China, Nigeria and Russia and 28 different ethnicities for the management of approximately 40 diseases. Bioactive compounds particularly cedrin, himachalol, himachalene and atlantone are recognized as key constituents for observed pharmacological activities of C. deodara. However, further in-depth studies involving bio-guided fractionation, isolation, identification using advanced techniques to afford some new therapeutically active phytoconstituents in the management of different diseases. Preliminary pharmacological investigations on different extracts and fractions of C. deodara partially validated its traditional claims in different ailments such as skin diseases, asthma, neurological disorders, arthritis, microbial infections, gastric disturbances, and inflammation. However, immediate attempts are required to establish its mechanism of action, efficacy, dosage range, and safety in combating different pathological states.

Recent advances in research on vine tea, a potential and functional herbal tea with dihydromyricetin and myricetin as major bioactive compounds

Vine tea has been used as an herbal tea by several ethnic minorities for hundreds of years in China. Flavonoids, a kind of indispensable component in a variety of nutraceutical, pharmaceutical and cosmetic applications, are identified to be the major metabolites and bioactive ingredients in vine tea. Interestingly, vine tea exhibits a wide range of significant bioactivities including anti-oxidant, anti-inflammatory, anti-tumor, antidiabetic, neuroprotective and other activities, but no toxicity. These bioactivities, to some extent, enrich the understanding about the role of vine tea in disease prevention and therapy. The health benefits of vine tea, particularly dihydromyricetin and myricetin, are widely investigated. However, there is currently no comprehensive review available on vine tea. Therefore, this report summarizes the most recent studies investigating bioactive constituents, pharmacological effects and possible mechanisms of vine tea, which will provide a better understanding about the health benefits and preclinical assessment of novel application of vine tea.

PEGylated dihydromyricetin-loaded nanoliposomes coated with tea saponin inhibit bacterial oxidative respiration and energy metabolism

The biofilms produced by the aggregation of bacterial colonies are among the major obstacles of host immune system monitoring and antimicrobial treatment. Herein, we report PEGylated dihydromyricetin-loaded liposomes coated with tea saponin grafted on chitosan (TS/CTS@DMY-lips) as an efficient cationic antibacterial agent against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), which is supported by their deep penetration into bacterial biofilms and broad pH-stable release performance of dihydromyricetin (DMY). The successful construction of the drug delivery system relied on tea saponin grafted on chitosan (TS/CTS) via formatted ester bonds or amido bonds as a polyelectrolyte layer of PEGylated dihydromyricetin-loaded liposomes (DMY lips), which achieved controlled release of DMY in weak acidic and neutral physiological environments. The micromorphology of TS/CTS@DMY-lips was observed to resemble dendritic cells with an average size of 266.49 nm, and they had excellent encapsulation efficiency (41.93%), water-solubility and stability in aqueous solution. Besides, TS/CTS@DMY-lips displayed effective destruction of bacterial energy metabolism and cytoplasmic membranes, resulting in the deformation of the cell wall and leaking of cytoplasmic constituents. Compared to free DMY, DMY lips and chitosan-coated dihydromyricetin liposomes (CTS@DMY-lips), TS/CTS@DMY-lips has more thorough killing activity against E. coli and S. aureus, which is related to its excellent sustained release performance of DMY under the protection of the TS/CTS coating.

Potent in vitro synergistic antibacterial activity of natural amphiphilic Sapindoside A and B against Cutibacterium acnes with destructive effect on bacterial membrane

Sapindus saponins are obtained from the outer bark of Sapindus mukorossi Gaertn. (S. mukorossi), and they have become an interesting subject in the search for new anti-acne agents without resistance. This study aimed to screen the synergistic antibacterial combination from Sapindus saponins and investigated the synergistic antibacterial action via targeting the cell membrane of Cutibacterium acnes (C. acnes) to reduce the effective dose. The combination of Sapindoside A and B (S_AB) was obtained with synergistic activity against C. acnes. S_AB led to the leakage of ions and disturbed the membrane morphology of C. acnes. The spectral features of cell membrane composition showed obvious changes based on Raman spectroscopy, and changes in membrane protein microenvironment were also observed by fluorescence spectroscopy. Among the above results, the contribution of Sapindoside A was greater than that of Sapindoside B to the synergistic combination of S_AB. Furthermore, molecular docking demonstrated that Sapindoside A interacted with penicillin-binding protein 2, playing an important role in peptidoglycan synthesis for the cross wall, and showed a higher binding score than Sapindoside B, further indicating that the greater contribution in the synergistic action of S_AB on membrane proteins. Collectively, these results showed that the synergistic antibacterial action of S_AB against C. acnes could be achieved by attacking cell membrane, and Sapindoside A played a major role, suggesting that S_AB has the potential to be the natural anti-acne agent additive in the cosmetic industry.

Australian propolis ethanol extract exerts antibacterial activity against methicillin-resistant Staphylococcus aureus by mechanisms of disrupting cell structure, reversing resistance, and resisting biofilm

The antibacterial activity and mechanisms of Australian propolis ethanol extract (APEE) against methicillin-resistant Staphylococcus aureus (MRSA) were investigated herein. The diameter of inhibition zones (DIZ) of APEE was 19.7 mm, while the minimum inhibition concentration (MIC) and minimum bactericide concentration (MBC) of APEE were both 0.9 mg/mL against the tested strain of MRSA. Nucleic acid leakage and propidium iodide (PI) staining assays showed that APEE can stimulate the release of intracellular nucleic acids by disrupting the integrity of the cell wall and cytoplasmic membrane. Scanning electron microscopy (SEM) further confirmed that APEE could depress cellular activities via damaging the cell structure, including the cell wall and membrane. Western blot analysis and β-lactamase activity assay showed that APEE could inhibit the expression of PBP2a and reduce the activity of β-lactamase, suggesting that APEE is able to reverse the drug resistance of MRSA. XTT and crystal violet (CV) assays indicated that APEE had the capacity to prevent the formation of biofilms through decreasing cellular activities and biomass. Bacterial adhesion assay revealed that APEE could reduce the adhesive capacity of the strain, belonging to its antibiofilm mechanisms. Furthermore, nine main compounds of APEE were identified and quantified by HPLC-DAD/Q-TOF-MS. The results above all verified that the antibacterial activity of APEE against MRSA was mainly due to disrupting cell structure, reversing resistance, and resisting biofilm formation, which indicates that APEE is expected to be an efficient functional ingredient with great potential application in the field of medicine and food.

A Novel Antimicrobial Peptides From Pine Needles of Pinus densiflora Sieb. et Zucc. Against Foodborne Bacteria

Pine needles are used in several East Asian countries as food or traditional medicine. It contains functional components that exhibit a wide spectrum of pharmacological effects such as antioxidant, antimicrobial, anti-diabetic, and anti-inflammatory activities. We determined and characterized the novel antimicrobial peptides (AMPs) isolated from Pinus densiflora Sieb. et Zucc. The four active pine-needle (PN) peptides showed antimicrobial activity against foodborne bacteria with minimum inhibitory concentration (MIC) values within the range of 8-128 μg/ml. PN peptides showed no detectable hemolytic activity or cytotoxicity at the antimicrobial concentrations. The N-terminal amino acid sequence of the PN5 was identified using Edman degradation and Antimicrobial Peptide Database (APD) homology analysis showed that it was not identical to any other plant peptide. This suggests that PN5 can serve as an alternative therapeutic agent to be used in the food industry.

Antibacterial Effect of Dihydromyricetin on Specific Spoilage Organisms of Hybrid Grouper

This study aimed to investigate the mechanism of antibacterial activity level inhibition of dihydromyricetin (DMY) against specific spoilage bacteria of grouper. Firstly, the specific spoilage bacteria of grouper in the cold storage process are Pseudomonas antarctica (P. antarctica), which are selected by calculating the spoilage metabolite yield factor. It was determined that the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of DMY against grouper spoilage bacteria were 2.0 mg/mL and 6.4 mg/mL, respectively. DMY was added to the matrix of chitosan and sodium alginate, and DMY emulsions of different concentrations (0 MIC, 1 MIC, 2 MIC, 4 MIC) were prepared and characterized by differential calorimetry methods. Through analyzing cell permeability, enzyme activity, and images of the confocal laser scanning microscope (CLSM), we further studied the antibacterial mechanism of DMY emulsion on specific spoilage bacteria. The results showed that, with the increase of DMY concentration in the treatment group, the leakage of nucleic acid and protein increased significantly, the activity of ATPase and three critical enzymes in the Embden-Meyerhof-Parnas (EMP) pathway decreased significantly, and the activity of AKPase did not decrease significantly, . The metabolic activity and viability are reduced considerably. Analysis of the above results shows that DMY inhibits the growth and reproduction of P. antarctica by interfering with the metabolic activity of bacteria and destroying the function of bacterial cell membranes but has no inhibitory effect on the activity of AKPase. This study proves that DMY could be an effective and natural antibacterial agent against specific spoilage bacteria in aquatic products.

Self-Assembled Micelles Improve the Oral Bioavailability of Dihydromyricetin and Anti-Acute Alcoholism Activity

Dihydromyricetin (DMY) is highly effective in counteracting acute alcohol intoxication. However, its poor aqueous solubility and permeability lead to the low oral bioavailability and limit its clinic application. The aim of this work is to use Solutol®HS15 (HS 15) as surfactant to develop novel micelle to enhance the oral bioavailability of DMY by improving its solubility and permeability. The DMY-loaded Solutol®HS15 micelles (DMY-Ms) were prepared by the thin-film hydration method. The particle size of DMY-Ms was 13.97 ± 0.82 nm with an acceptable polydispersity index of 0.197 ± 0.015. Upon entrapped in micelles, the solubility of DMY in water was increased more than 25-fold. The DMY-Ms had better sustained release property than that of pure DMY. In single-pass intestinal perfusion models, the absorption rate constant (Ka) and permeability coefficient (Papp) of DMY-Ms were 5.5-fold and 3.0-fold than that of pure DMY, respectively. The relative bioavailability of the DMY-Ms (AUC_0-∞) was 205% compared with that of pure DMY (AUC_0-∞), indicating potential for clinical application. After administering DMY-Ms, there was much lower blood alcohol level and shorter duration of the loss of righting relax (LORR) in drunk animals compared with that treated by pure DMY. In addition, the oral administration of DMY-Ms greatly reduced oxidative stress, and significantly defended liver and gastric mucosa from alcoholic damages in mice with alcohol-induced tissue injury. Taken together, HS 15-based micelle system greatly improves the bioavailability of DMY and represents a promising strategy for the management of acute alcoholism. Graphical abstract.

Dihydromyricetin incorporated active films based on konjac glucomannan and gellan gum

Active composite films were developed by incorporating different concentration of dihydromyricetin (DMY) into konjac glucomannan (KGM)/gellan gum (GG) matrix. Physicochemical, mechanical, released behaviour, antioxidant and antimicrobial properties of composite films were investigated. The results from the Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) indicated that DMY which well-dispersed in the KGM/GG matrix interacted with matrix through hydrogen bonds. The obtained films presented predominant thermostability, good water resistance property, excellent ultraviolet light barrier ability and sustained controlled release behaviour. In particular, the incorporation of DMY remarkably enhanced the antioxidant and antimicrobial activities of the films. Overall, the fabricated KGM/GG-DMY composite films have a promising application in the fields of food packaging.

Synergistic effects of endolysin Lysqdvp001 and ε-poly-lysine in controlling Vibrio parahaemolyticus and its biofilms

The synergistic antibacterial effects between endolysin Lysqdvp001 and ε-poly-lysine (ε-PL) against Vibrio parahaemolyticus (V. parahaemolyticus) were investigated in this study. Lysqdvp001 combined with ε-PL exhibited a strong antibacterial synergism against V. parahaemolyticus. The combinations of Lysqdvp001 (≥60 U/mL) and ε-PL (≥0.2 mg/mL) dramatically decreased cell density of the bacterial suspensions at both 25 °C and 37 °C. Surface zeta potential increment and membrane hyperpolarization of V. parahaemolyticus were observed after treatment by ε-PL and its combination with Lysqdvp001. More β-lactamase and β-galactosidase were leaked from V. parahaemolyticus with combined treatment of Lysqdvp001 and ε-PL than from the bacteria treated with single Lysqdvp001 or ε-PL. Fluorescence and transmission electron microscope revealed that Lysqdvp001 and ε-PL synergistically induced the damage and morphological destruction of V. parahaemolyticus cells. When applying in Gadus macrocephalus, Penaeus orientalis and oyster, the two antimicrobials' cocktail allowed for 3.75, 4.16 and 2.50 log₁₀CFU/g reductions of V. parahaemolyticus, respectively. Besides, Lysqdvp001 in combination with ε-PL removed approximately 44%-68% of V. parahaemolyticus biofilms on polystyrene, glass and stainless steel surfaces. These results demonstrated that Lysqdvp001 and ε-PL might be used together for controlling V. parahaemolyticus and the bacterial biofilms in food industry.

Eco-Friendly and Facile Synthesis of Antioxidant, Antibacterial and Anticancer Dihydromyricetin-Mediated Silver Nanoparticles

Background

Dihydromyricetin (DMY), a natural flavonoid, has reportedly antibacterial, antioxidant, anticancer and other properties. In the present study, DMY was used as a reducing agent and stabilizer to synthesize silver nanoparticles (AgNPs), and the optimal conditions for its synthesis were studied. The DMY-AgNPs were investigated for their DPPH scavenging properties and their potential against human pathogenic and food-borne bacteria viz. Escherichia coli (E. coli), and Salmonella. In addition, DMY-AgNPs also showed excellent inhibitory effects on cancer Hela, HepG2 and MDA-MB-231 cell lines.

Methods

The dihydromyricetin-mediated AgNPs (DMY-AgNPs) were characterized by ultraviolet-visible spectrophotometer (UV-Vis spectra), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray powder diffraction (XRD). Antioxidant activity of DMY-AgNPs was determined by 1.1-diphenyl-2-picrylhydrazyl (DPPH) scavenging. The antibacterial activity was determined by 96-well plate (AGAR) gradient dilution, while anticancer potential was determined by MTT assay.

Results

The results showed that the dispersion of AgNPs had the maximum UV-visible absorption at about 410 nm. The synthesized nanoparticles were almost spherical. FTIR was used to identify functional groups that may lead to the transformation of metal ions into nanoparticles. The results showed that the prepared AgNPs were coated with biological molecules in the extraction solution. The biosynthesized DMY-AgNPs exhibited good antioxidant properties, at various concentrations (0.01-0.1mg/mL), the free radical scavenging rate was about 56-92%. Furthermore, DMY-AgNPs possessed good antibacterial properties against Escherichia coli (E. coli), and Salmonella at room temperature. The minimum inhibitory concentrations (MIC) were 10^-6 g/L, and 10^-4 g/L, respectively. The bioactivity of DMY-mediated AgNPs was studied using MTT assay against Hela, HepG2 and MDA-MB-231 cancer cell lines, and all showed good inhibitory effects.

Conclusion

The present study provides a green approach for the synthesis of DMY-AgNPs which exhibited stronger antioxidant, antibacterial and anticancer properties compared to the dihydromyricetin. DMY-AgNPs can serve as an economical, efficient, and effective antimicrobial material for its applications in food and pharmaceutical fields.

Mechanism and antibacterial activity of vine tea extract and dihydromyricetin against Staphylococcus aureus

Vine tea (Ampelopsis grossedentata) has been approved as a new food ingredient in 2013. Both vine tea extract (VTE) and its active ingredient, 2R, 3R-Dihydromyricetin (DMY), showed good antibacterial activity. The mechanism of VTE and DMY against Staphylococcus aureus were evaluated by morphology observation, cell membrane and wall assay, protein assay, and DNA assay in this study. The results of SEM and TEM revealed that the VTE and DMY changed the morphology of S. aureus. The leakage of AKPase and β-galactosidase in treated groups demonstrated that the membrane integrity of S. aureus was disrupted. Meanwhile, the results of protein assay showed that VTE and DMY inhibited the expression of total proteins, and decreased activities of a few energy metabolism enzymes, total ATPase. Moreover, spectral and competitive analysis revealed that VTE and DMY interacted with DNA by groove and intercalation binding. Finally, the suspension experiments of Chinese cabbage and barley showed that inhibitors had strong inhibitory effect on bacteria growth. Overall, the results suggested that VTE and DMY may be potential food preservatives for inhibiting pathogen.

iTRAQ-based quantitative proteomic analysis of synergistic antibacterial mechanism of phenyllactic acid and lactic acid against Bacillus cereus

Phenyllactic acid (PLA) as a phenolic acid by lactic acid (LA) bacteria shows enhanced antibacterial activity when coexisting with LA, while the antibacterial mechanism of PLA combined with LA was unknown. Hence, the antibacterial mechanism of PLA and LA was investigated against Bacillus cereus. Flow cytometry and TEM analysis demonstrated that single PLA and LA disrupted the membrane integrity and the morphology, while combined PLA and LA synergistically enhanced the damage. iTRAQ-based proteomic analysis suggested that PLA down-regulated kdpB and inhibited K⁺ transport, disturbed the function of ribosome and expression of competence genes; LA down-regulated periplasmic phosphorus-binding proteins and inhibited phosphorus transport, disturbed the function of ribosome, TCA cycle, as well as purine and pyrimidine metabolism; and combined PLA and LA inhibited K⁺ and phosphorus transport, and influenced the synthesis of purine and pyrimidine metabolism. The investigation could provide some insights into the application of PLA in food preservation.

An enhanced antibacterial nanoflowers AgPW@PDA@Nisin constructed from polyoxometalate and nisin

A new composite, AgPW@PDA@Nisin, with shell-core structure was successfully synthesized by a polydopamine (PDA) surfaced conjugated nisin (an antibacterial 34 amino acid polycyclic peptide) as shell and polyoxometalates (Ag₃PW₁₂O₄₀ = AgPW) as core. The composite was characterized by the zeta potential, scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction analysis (XRD), fourier transform infrared (FT-IR). The AgPW@PDA@Nisin showed flower hierarchical structure and potential antibacterial activity against S. aureus ATCC29213. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of it were 4 and 32 μg/mL. AgPW@PDA@Nisin nanoflowers-induced bacterial death bears the characteristic of cell morphology, membrane integrity and permeability changing, nucleotide leakage. It indicated that the AgPW@PDA@Nisin interfere with the cell membrane, resulting in antibacterial activity against S. aureus. The cytotoxicity of the nanoflowers was low on HDF-a (human dermal fibroblasts) cells. A new class of hybrid inorganic-organic nanoflowers based on polyoxometalates and nisin with enhanced antibacterial properties can be developed for food preservation.

GC-MS Phytochemical Profiling, Pharmacological Properties, and In Silico Studies of Chukrasia velutina Leaves: A Novel Source for Bioactive Agents

Chukrasia velutina is a local medicinal plant commonly known as chikrassy in Bangladesh, India, China, and other South Asian countries. The leaves, bark, and seeds are vastly used as herbal medicine for fever and diarrhea, and its leaves essential oils are used for antimicrobial purposes. In this study, we discuss the neuropsychiatric properties of C. velutina leaves through several animal models, quantitative and qualitative phytochemical analysis, and computational approaches. Neuropsychiatric effects were performed in rodents on the methanolic extract of C. velutina leaves (MECVL). Antidepressant, anxiolytic, and sedative effects experimented through these rodent models were used such as the force swimming test (FST), tail suspension test (TST), hole board test (HBT), elevated plus maze test (EPMT), light/dark box test (LDBT), open field test (OFT), and hole cross test (HCT). In these rodent models, 200 and 400 mg/kg doses were used which exhibited a significant result in the force swimming and tail suspension test (p < 0.001) for the antidepressant effect. In the anxiolytic study, the results were significant in the hole board, elevated plus maze, and light/dark box test (p < 0.001) for doses of 200 and 400 mg/kg. The result was also significant in the open field and hole cross test (p < 0.001) for sedative action in the sake of similar doses. Moreover, qualitative and quantitative studies were also performed through phytochemical screening and GC-MS analysis, and fifty-seven phytochemical compounds were found. These compounds were analyzed for pharmacokinetics properties using the SwissADME tool and from them, thirty-five compounds were considered for the molecular docking analysis. These phytoconstituents were docking against the human serotonin receptor, potassium channel receptor, and crystal structure of human beta-receptor, where eight of the compounds showed a good binding affinity towards the respective receptors considered to the reference standard drugs. After all of these analyses, it can be said that the secondary metabolite of C. velutina leaves (MECVL) could be a good source for inhibiting the neuropsychiatric disorders which were found on animal models as well as in computational studies.

Exploring the antibacterial mechanism of essential oils by membrane permeability, apoptosis and biofilm formation combination with proteomics analysis against methicillin-resistant staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the important causes of food poisoning and infectious diseases worldwide, it can produce a large number of virulence factors, enhance the colonization ability of the host so that it can quickly colonize and spread on the surface of the objects. Essential oil (EO) is one of the natural products with antimicrobial properties, can be used as an important source of antibacterial agent discovery, and has a broad development prospect. However, the unclear mechanisms of antibacterial action have become an obstacle to its further development and use. Hence, the objective of the present study was to reveal the antibacterial mechanism of EO from Amomum villosum Lour (A villosum Lour) against MRSA using label-free quantitative proteomics, investigate the effect of EO on the bacterial proteome, enzymatic activities and leakage of bacterial intracellular biomacromolecule. Proteomic analysis of MRSA in the presence of EO found that a total of 144 differential expressed proteins (DEPs) between the control and treatment group, in which 42 proteins were distinctly up-regulated and 102 proteins were down-regulated. Besides, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, determination of cell membrane permeability and apoptosis, scanning electron microscopy (SEM) observations, bacterial surface hydrophobicity, and biofilm formation measurement were performed. Collectively, the above results indicated that the cell membrane damage by EO leads to the loss of membrane integrity and causes leakage of intracellular macromolecular substances, inhibition of protein, and biofilm synthesis. These findings manifested that EO exerts antibacterial effect by multiple avenues and expands our understanding of the antibacterial mechanism, it has potential application value in food preservative and pharmaceutical industries.

Evaluation of the anti-cancer potential of Cedrus deodara total lignans by inducing apoptosis of A549 cells

BACKGROUND

Cedrus deodara (Roxb.) Loud (normally called as deodar), one out of four species in the genus Cedrus, exhibits widely biological activities. The Cedrus deodara total lignans from the pine needles (CTL) were extracted. The aim of the study was to investigate the anticancer potential of the CTL on A549 cell line.

METHODS

We extracted the CTL by ethanol and assessed the cytotoxicity by CCK-8 method. Cell cycle and apoptosis were detected by a FACS Verse Calibur flow cytometry.

RESULTS

The CTL were extracted by means of ethanol hot refluxing and the content of total lignans in CTL was about 55.77%. By the CCK-8 assays, CTL inhibited the growth of A549 cells in a dose-dependent fashion, with the IC50 values of 39.82 ± 1.74 μg/mL. CTL also inhibited the growth to a less extent in HeLa, HepG2, MKN28 and HT-29 cells.

CONCLUSION

At low doses, the CTL effectively inhibited the growth of A549 cells. By comparison of IC50 values, we found that A549 cells might be more sensitive to the treatment with CTL. In addition, CTL were also able to increase the population of A549 cells in G2/M phase and the percentage of apoptotic A549 cells. CTL may have therapeutic potential in lung adenocarcinoma cancer by regulating cell cycle and apoptosis.

Dihydromyricetin: A review on identification and quantification methods, biological activities, chemical stability, metabolism and approaches to enhance its bioavailability

BACKGROUND

Dihydromyricetin (DMY) is an important plant flavonoid, which has received great attention due to its health-benefiting activities, including antioxidant, antimicrobial, anti-inflammatory, anticancer, antidiabetic and neuroprotective activities. DMY capsules have been sold in US as a nutraceutical supplement to prevent alcoholic hangovers. The major disadvantage associated with DMY is its chemical instability and poor bioavailability caused by the combined effects of its low solubility and poor membrane permeability. This limits its practical use in the food and pharmaceutical fields.

SCOPE AND APPROACH

The present paper gives an overview of the current methods for the identification and quantification of DMY. Furthermore, recent findings regarding the main biological properties and chemical stability of DMY, the metabolism of DMY as well as different approaches to increase DMY bioavailability in both aqueous and lipid phases are discussed.

KEY FINDINGS AND CONCLUSIONS

Current trends on identification and quantification of DMY have been focused on spectral and chromatographic techniques. Many factors such as heat, pH, metal ions, could affect the chemical stability of DMY. Despite the diverse biological effects of DMY, DMY faces with the problem of poor bioavailability. Utilization of different delivery systems including solid dispersion, nanocapsule, microemuslion, cyclodextrin inclusion complexes, co-crystallization, phospholipid complexes, and chemical or enzymatic acylation has the potential to improve both the solubility and bioavailability. DMY digested in laboratory animals undergoes reduction, dehydroxylation, methylation, glucuronidation, and sulfation. Novel DMY delivery systems and basic pharmacokinetic studies of encapsulated DMY on higher animals and humans might be required in the future.

Synergy between dihydromyricetin intervention and irinotecan chemotherapy delays the progression of colon cancer in mouse models

Colorectal cancer (CRC) is the third highest cause of cancer-related death and the main option for prolonged survival is chemotherapeutic intervention. There is increasing interest in dietary intervention using natural agents to enhance the sensitivity of such invasive chemical treatment. In this study, the chemotherapeutic efficacy of dihydromyricetin (DMY) intervention on treatments involving irinotecan (CPT-11) or gemcitabine (GM) was evaluated in an AOM/DSS-induced colitis-associated colon cancer model and a Min (Apc Min/+) mice model. Our data showed that DMY could promote the CPT-11 effect both in the mouse model of AOM/DSS and Apc Min/+ cancer and had no influence on the GM effect. In AOM/DSS cancer, tumors were sensitive to 100 mg kg-1 DMY chemotherapy under 100 mg kg-1 or 200 mg kg-1 CPT-11. DMY-driven CPT-11 chemotherapy induced enhanced IgG levels and the reduction of Fusobacterium abundance in the gut. In the Min model, CPT-11 with 20 mg kg-1 DMY prevented tumor formation but not with 100 mg kg-1 DMY. Mechanically, chloride ion-dependent CFTR, CLCN4, and CLIC4 signaling are not involved in DMY mediated chemotherapeutic colon tumorigenesis. These results suggested that a suitable dose of DMY could act as a coadjuvant to CPT-11 chemotherapy.

Antibacterial Activity and Mode of Action of Dihydromyricetin from Ampelopsis grossedentata Leaves against Food-Borne Bacteria

Dihydromyricetin (DMY) has recently attracted increased interest due to its considerable health-promoting activities but there are few reports on its antibacterial activity and mechanism. In this paper, the activity and mechanisms of DMY from Ampelopsis grossedentata leaves against food-borne bacteria are investigated. Moreover, the effects of pH, thermal-processing, and metal ions on the antibacterial activity of DMY are also evaluated. The results show that DMY exhibits ideal antibacterial activity on five types of food-borne bacteria (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Salmonella paratyphi, and Pseudomonas aeruginosa). The activities of DMY against bacteria are extremely sensitive to pH, thermal-processing, and metal ions. The morphology of the tested bacteria is changed and damaged more seriously with the exposure time of DMY. Furthermore, the results of the oxidative respiratory metabolism assay and the integrity of the cell membrane and wall tests revealed that the death of bacteria caused by DMY might be due to lysis of the cell wall, leakage of intracellular ingredients, and inhibition of the tricarboxylic acid cycle (TCA) pathway.

Preparation of a nanoscale dihydromyricetin-phospholipid complex to improve the bioavailability: in vitro and in vivo evaluations

Dihydromyricetin (DMY), a flavanonol compound found as the most abundant and bioactive constituent in Ampelopsis grossedentata (Hand-Mazz) W.T. Wang, possesses numerous pharmacological activities, such as antioxidant, anti-inflammation, anticancer, anti-microbial, hypoglycemic and hypolipidemic effects, and so on. Recently, DMY shows a promising potential to develop as an agent for the prevention and treatment of Type 2 diabetes mellitus (T2DM). However, the low oral bioavailability of DMY was one of the special concerns to be resolved for its clinical applications. In this study, DMY phospholipid complex (DMY-HSPC COM) was prepared by the solvent evaporation technique and optimized with DMY combination ratio. Scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and Fourier transform infrared spectrophotometry (FT-IR) were carried to characterize the formation of DMY-HSPC COM. The particle size, zeta potential, drug loading and solubility of DMY-HSPC COM were further investigated. The phospholipid complex technology could significantly improve the solubility of DMY. Pharmacokinetic study results of DMY-HSPC COM in healthy SD rats and T2DM rats demonstrated that the oral bioavailability was significantly increased when compared with pure DMY as well, which could be attributed to the improvement of the aqueous solubility of the complex, absorption promotion and a probable decrease in intestinal and hepatic metabolism. In addition, when compared with healthy SD rats, pharmacokinetic parameters of pure DMY and DMY-HSPC COM showed significant difference in T2DM rats. Thus, phospholipid complex technology holds a promising potential for increasing the oral bioavailability of DMY.

Response of Arthrobacter QD 15-4 to dimethyl phthalate by regulating energy metabolism and ABC transporters

Ubiquitous dimethyl phthalate (DMP) has severely threatened environmental safety and the health of organisms. Therefore, it is necessary to degrade DMP, removing it from the environment. Microbiological degradation is an efficient and safe method for degrading DMP. In this study, the response of Arthrobacter QD 15-4 to DMP was investigated. The results showed that the growth of Arthrobacter QD 15-4 was not impacted by DMP and Arthrobacter QD 15-4 could degrade DMP. RNA-Seq and RT-qPCR results showed that DMP treatment caused some changes in the expression of key genes in Arthrobacter QD 15-4. The transcriptional expressions of pstSCAB and phoU were downregulated by DMP. The transcriptional expressions of potACD, gluBC, oppAB, pdhAB, aceAF, gltA were upregulated by DMP. The genes are mainly involved in regulating energy metabolism and ATP-binding cassette (ABC) transporters. The increasing of pyruvic acid and citrate in Arthrobacter QD 15-4 further supported the energy metabolism was improved by DMP. It was clearly shown that Arthrobacter QD 15-4 made response to dimethyl phthalate by regulating energy metabolism and ABC transporters.

Pathogen-Specific Polymeric Antimicrobials with Significant Membrane Disruption and Enhanced Photodynamic Damage To Inhibit Highly Opportunistic Bacteria

Highly pathogenic Gram-negative bacteria and their drug resistance are a severe public health threat with high mortality. Gram-negative bacteria are hard to kill due to the complex cell envelopes with low permeability and extra defense mechanisms. It is challenging to treat them with current strategies, mainly including antibiotics, peptides, polymers, and some hybrid materials, which still face the issue of drug resistance, limited antibacterial selectivity, and severe side effects. Together with precise bacteria targeting, synergistic therapeutic modalities, including physical membrane damage and photodynamic eradication, are promising to combat Gram-negative bacteria. Herein, pathogen-specific polymeric antimicrobials were formulated from amphiphilic block copolymers, poly(butyl methacrylate)- b-poly(2-(dimethylamino) ethyl methacrylate- co-eosin)- b-ubiquicidin, PBMA- b-P(DMAEMA- co-EoS)-UBI, in which pathogen-targeting peptide ubiquicidin (UBI) was tethered in the hydrophilic chain terminal, and Eosin-Y was copolymerized in the hydrophilic block. The micelles could selectively adhere to bacteria instead of mammalian cells, inserting into the bacteria membrane to induce physical membrane damage and out-diffusion of intracellular milieu. Furthermore, significant in situ generation of reactive oxygen species was observed upon light irradiation, achieving further photodynamic eradication. Broad-spectrum bacterial inhibition was demonstrated for the polymeric antimicrobials, especially highly opportunistic Gram-negative bacteria, such as Pseudomona aeruginosa ( P. aeruginosa) based on the synergy of physical destruction and photodynamic therapy, without detectable resistance. In vivo P. aeruginosa-infected knife injury model and burn model both proved good potency of bacteria eradication and promoted wound healing, which was comparable with commercial antibiotics, yet no risk of drug resistance. It is promising to hurdle the infection and resistance suffered from highly opportunistic bacteria.

Response of Pseudomonas fluorescens to dimethyl phthalate

Dimethyl phthalate (DMP) is a ubiquitous pollutant that is very harmful to organisms due to its mutagenicity, teratogenicity and carcinogenicity. Pseudomonas fluorescens (P. fluorescens) is one of the most important bacteria in the environment. In this study, the response of P. fluorescens to DMP was investigated. It was found that DMP greatly inhibited the growth and glucose utilization of P. fluorescens when the concentration of DMP was ranged from 20 to 40 mg/l. The surface hydrophobicity and membrane permeability of P. fluorescens were also increased by DMP. DMP could lead to the deformations of cell membrane and the mis-opening of membrane channels. RNA-Seq and RT-qPCR results showed that the expression of some genes in P. fluorescens were altered, including the genes involved in energy metabolism, ATP-binding cassette (ABC) transporting and two-component systems. Additionally, the productions of lactic acid and pyruvic acid were reduced and the activity of hexokinase was inhibited in P. fluorescens by DMP. Clearly, the results suggested that DMP contamination could alter the biological function of P. fluorescens in the environment.

Dihydromyricetin Inhibits Inflammation of Fibroblast-Like Synoviocytes through Regulation of Nuclear Factor-κB Signaling in Rats with Collagen-Induced Arthritis

Dihydromyricetin (DMY), the main flavonoid of Ampelopsis grossedentata, has potent anti-inflammatory activity. However, the effect of DMY on chronic autoimmune arthritis remains undefined. In this study, we investigated the therapeutic effects of DMY on collagen-induced arthritis (CIA). Wistar rats were immunized with bovine type II collagen to establish CIA and were then administered DMY intraperitoneally (5, 25, and 50 mg/kg) every other day for 5 weeks. Paw swelling, clinical scoring, and histologic analysis were assessed to determine the therapeutic effects of DMY on the development of arthritis in CIA rats. The results showed that treatment with DMY significantly reduced erythema and swelling in the paws of CIA rats. Pathologic analysis of the knee joints and peripheral blood cytokine assay results confirmed the antiarthritic effects of DMY on synovitis and inflammation. Fibroblast-like synoviocytes (FLSs) were isolated from the synovium of CIA rats and treated with 10 ng/ml interleukin (IL)-1β DMY significantly inhibited the proliferation, migration, and inflammation of IL-1β-induced FLSs, whereas it significantly increased IL-1β-induced FLS apoptosis in a dose-dependent manner (6.25-25 μM). Moreover, DMY suppressed phosphorylation of IκB kinase (IKK) and inhibitor of NF-κB α and subsequently reduced the IL-1β-induced nucleus translocation of NF-κB in FLSs. Through a molecular docking assay, we demonstrated that DMY could directly bind to the Thr9 and Asp88 residues in IKKα and the Asp95, Asn142, and Gln167 residues in IKKβ These findings demonstrate that DMY could alleviate inflammation in CIA rats and attenuate IL-1β-induced activities in FLSs through suppression of NF-κB signaling.

Recent Update on the Pharmacological Effects and Mechanisms of Dihydromyricetin

As the most abundant natural flavonoid in rattan tea, dihydromyricetin (DMY) has shown a wide range of pharmacological effects. In addition to the general characteristics of flavonoids, DMY has the effects of cardioprotection, anti-diabetes, hepatoprotection, neuroprotection, anti-tumor, and dermatoprotection. DMY was also applied for the treatment of bacterial infection, osteoporosis, asthma, kidney injury, nephrotoxicity and so on. These effects to some extent enrich the understanding about the role of DMY in disease prevention and therapy. However, to date, we still have no outlined knowledge about the detailed mechanism of DMY, which might be related to anti-oxidation and anti-inflammation. And the detailed mechanisms may be associated with several different molecules involved in cellular apoptosis, oxidative stress, and inflammation, such as AMP-activated protein kinase (AMPK), mitogen-activated protein kinase (MAPK), protein kinase B (Akt), nuclear factor-κB (NF-κB), nuclear factor E2-related factor 2 (Nrf2), ATP-binding cassette transporter A1 (ABCA1), peroxisome proliferator-activated receptor-γ (PPARγ) and so on. Here, we summarized the current pharmacological developments of DMY as well as possible mechanisms, aiming to push the understanding about the protective role of DMY as well as its preclinical assessment of novel application.

Antibacterial and Antibiofilm Effects of Zanthoxylum bungeanum Leaves against Staphylococcus aureus

Biofilm formation by Staphylococcus aureus on food contact surfaces is one of the most important issues for the food safety. The difficulties in controlling biofilms have driven the search for new antibacterial and antibiofilm agents from natural resources. The aims of the present study were to investigate the antibacterial and antibiofilm activities of the methanolic extract from Zanthoxylum bungeanum Maxim. leaves and identify the active compounds. By bioassay guide of inhibitory activity against S. aureus, four antibacterial compounds were separated from this extract and identified as neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid and 4- O-caffeoyl-2,3-dihydroxy-2- C-methylbutyric acid based on MS and NMR data analyses. The four compounds exhibited moderate antibacterial activity against S. aureus with minimum inhibitory concentration of 5 mg/mL. Moreover, a fraction consisted of the four compounds was subjected to antibiofilm assays against S. aureus. Crystal violet staining and XTT reduction assay demonstrated that this fraction showed an excellent inhibitory efficacy on the biomass and metabolic activity of S. aureus biofilm. Scanning electron microscopic observation displayed that this fraction induced severe morphological changes in the architecture of S. aureus biofilm, which further confirmed that it possessed a potent inhibitory activity on the biofilm formation of S. aureus. So, these results suggested that Z. bungeanum leaves could be used as an attractive and promising candidate for the development of natural antibacterial agent for controlling food-related bacterial biofilms.

Dihydromyricetin induces apoptosis in a human choriocarcinoma cell line

Choriocarcinoma is a malignant trophoblastic tumor. The development of novel drugs is required to reduce the toxicity of current multi-agent chemotherapy and to successfully treat chemoresistant cases of the disease. The purpose of the present study was to investigate the effect of dihydromyricetin (DMY) on the human choriocarcinoma cell line, JAr, to identify a novel drug for the treatment of choriocarcinoma. An MTT assay was performed to determine the effects of DMY at different concentrations and for different exposure durations. Flow cytometry and TUNEL assays were performed to detect apoptosis, and western blotting was utilized to investigate the underlying mechanism. The results revealed that DMY significantly inhibited JAr cell viability in a time- and dose-dependent manner. The flow cytometry and TUNEL assays demonstrated that DMY inhibited proliferation by inducing apoptosis. Further analysis by western blotting indicated that the protein expression level of BCL-2 associated X, associated protein increased, while the protein expression levels of BCL-2 and pro-caspase-3 decreased. These findings suggest that DMY induced apoptosis in human choriocarcinoma JAr cells, through a mitochondrially mediated apoptotic pathway.

Antioxidant and antimicrobial efficacy of a biflavonoid, amentoflavone from Nandina domestica in vitro and in minced chicken meat and apple juice food models

A biflavonoid, amentoflavone isolated from Nandina domestica and characterized by NMR spectral-data analyses was assessed for its antioxidant, and antibacterial potential in vitro and in food-model systems. Amentoflavone exhibited potent antioxidant ability (19.21-75.52%) on scavenging DPPH, ABTS, superoxide, and hydroxyl radicals. Fluorescent images confirmed bacterial membrane depolarization of both the tested pathogens Staphylococcus aureus and Escherichia coli, with a significant reduction in cell viabilities at their respective MIC of 62.5 and 125 µg/mL. Increasing rates of membrane permeability observed in 260 nm-absorbing material, potassium ion, extracellular ATP, and relative electrical conductivity assays confirmed antibacterial mechanistic role of amentoflavone as also evidenced by microscopic studies of SEM and TEM. There was a marked inhibitory effect of amentoflavone with a significant reduction in cell counts of S. aureus and E. coli in minced chicken and apple juice at 4 °C, thus suggesting its nutritional enhancing efficacy as a natural antioxidant and antimicrobial agent.

Antibacterial Effect of (2E,2E)-4,4-Trisulfanediylbis(but-2-enoic acid) against Staphylococcus aureus

A new highly active molecule, (2E, 2E)-4,4-trisulfanediylbis(but-2-enoic acid) (TSDB), was designed and synthesized through comparative molecular field analysis with the diallyl trisulfide structure of garlic. TSDB exerted a strong inhibitory effect against Staphylococcus aureus, with minimal inhibitory and minimal bactericidal concentrations of 16 and 128 μg/mL, respectively. TSDB destructed the integrity of the S. aureus cell membrane but weakly damaged the bacterial cell wall. TSDB also increased the conductivity and protein expression in microbial broth but minimally influenced the level of extracellular alkaline phosphatase. TSDB could be a novel food preservative.

Interactions of Dihydromyricetin, a Flavonoid from Vine Tea (Ampelopsis grossedentata) with Gut Microbiota

Dihydromyricetin (DMY) is the main bioactive constituent in vine tea (Ampelopsis grossedentata), which was predominantly distributed in the gastrointestinal tract and showed poor oral bioavailability. Our aim was to systematically investigate the interactions of DMY with gut microbiota. Through the metabolism study of DMY by fecal microflora in vitro, it was found that DMY could be metabolized into three metabolites by fecal microflora via reduction and dehydroxylation pathways, and the dehydroxylation metabolite was the dominant one. Meanwhile, in order to consider the influence of gut microbiota metabolism on the pharmacokinetics of DMY, the pharmacokinetics of DMY in control and pseudo-germ-free rats were compared. It was shown that area under the curve (AUC) could only slightly increase, however, peak concentration (C_max ) could significantly increase in the pseudo-germ-free rats compared with the control rats, which indicated the gut microbiota metabolism played an important role in the pharmacokinetics of DMY. In addition, the long-term influence of DMY on gut microbiota composition by using 16S rRNA pyrosequencing was further investigated. And it was found that DMY could markedly alter the richness and diversity of the gut microbiota and modulate the gut microbiota composition. The present findings will be helpful for the future development and clinical application of DMY.

PRACTICAL APPLICATION

The gut microbiota plays an important role in the pharmacokinetics of flavonoids. As well, the long-term supplements of flavonoids could alter the gut microbiota composition in turn. The study aims to clarify the mutual interaction of DMY with gut microbiota, which may lead to new information with respect to the mechanism study and clinical application of DMY.

Qualitative and quantitative assessment of DNA quality of frozen beef based on DNA yield, gel electrophoresis and PCR amplification and their correlations to beef quality

Freezing is a practical method for meat preservation but the quality of frozen meat can deteriorate with storage time. This research investigated the effect of frozen storage time (up to 66 months) on changes in DNA yield, purity and integrity in beef, and further analyzed the correlation between beef quality (moisture content, protein content, TVB-N value and pH value) and DNA quality in an attempt to establish a reliable, high-throughput method for meat quality control. Results showed that frozen storage time influenced the yield and integrity of DNA significantly (p < 0.05). The DNA yield decreased as frozen storage time increased due to DNA degradation. The half-life (t_1/2 = ln2/0.015) was calculated as 46 months. The DNA quality degraded dramatically with the increased storage time based on gel electrophoresis results. Polymerase chain reaction (PCR) products from both mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) were observed in all frozen beef samples. Using real-time PCR for quantitative assessment of DNA and meat quality revealed that correlations could be established successfully with mathematical models to evaluate frozen beef quality.

Anti-Phytopathogenic and Cytotoxic Activities of Crude Extracts and Secondary Metabolites of Marine-Derived Fungi

Thirty-one isolates belonging to eight genera in seven orders were identified from 141 strains that were isolated from several marine plants. Alternaria sp. and Fusarium sp. were found to be the predominant fungi. Evaluation of the anti-phytopathogenic bacterial and fungal activities, as well as the cytotoxicity of these 31 extracts, revealed that most of them displayed different levels of bioactivities. Due to their interesting bioactivities, two fungal strains—Fusarium equiseti (P18) and Alternaria sp. (P8)—were selected for chemical investigation and compounds 1–4 were obtained. The structure of 1 was elucidated by 1D and 2D NMR analysis, as well as high-resolution electrospray ionization mass spectroscopy (HRESIMS), and the absolute configuration of its stereogenic carbon (C-11) was established by comparison of the experimental and calculated electronic circular-dichroism (ECD) spectra. Moreover, alterperylenol (4) exhibited antibacterial activity against Clavibacter michiganensis with a minimum inhibitory concentration (MIC) of 1.95 μg/mL, which was 2-fold stronger than that of streptomycin sulfate. Additionally, an antibacterial mechanism study revealed that 4 caused membrane hyperpolarization without evidence of destruction of cell membrane integrity. Furthermore, stemphyperylenol (3) displayed potent antifungal activity against Pestallozzia theae and Alternaria brassicicola with MIC values equal to those of carbendazim. The cytotoxicity of 1 and 2 against human lung carcinoma (A-549), human cervical carcinoma (HeLa), and human hepatoma (HepG2) cell lines were also evaluated.

Antibacterial Effect of 2R,3R-dihydromyricetin on the Cellular Functions of Staphylococcus aureus

The C-3-OH, C-4 carbonyl oxygen and hydrogenation of C2=C3 bond on the C-ring of 2R,3R-dihydromyricetin (DMY) proved to be not necessary for the antibacterial activity against Staphylococcus aureus. DMY significantly decreased the intracellular ATP of S. aureus cells but had few effects on pH_in, proline oxidation, succinate dehydrogenase activity or malate dehydrogenase activity.

Modification of membrane properties and fatty acids biosynthesis-related genes in Escherichia coli and Staphylococcus aureus: Implications for the antibacterial mechanism of naringenin

In this work, modifications of cell membrane fluidity, fatty acid composition and fatty acid biosynthesis-associated genes of Escherichia coli ATCC 25922 (E. coli) and Staphylococcus aureus ATCC 6538 (S. aureus), during growth in the presence of naringenin (NAR), one of the natural antibacterial components in citrus plants, was investigated. Compared to E. coli, the growth of S. aureus was significantly inhibited by NAR in low concentrations. Combination of gas chromatography-mass spectrometry with fluorescence polarization analysis revealed that E. coli and S. aureus cells increased membrane fluidity by altering the composition of membrane fatty acids after exposure to NAR. For example, E. coli cells produced more unsaturated fatty acids (from 18.5% to 43.3%) at the expense of both cyclopropane and saturated fatty acids after growth in the concentrations of NAR from 0 to 2.20mM. For S. aureus grown with NAR at 0 to 1.47mM, the relative proportions of anteiso-branched chain fatty acids increased from 37.2% to 54.4%, whereas iso-branched and straight chain fatty acids decreased from 30.0% and 33.1% to 21.6% and 23.7%, respectively. Real time q-PCR analysis showed that NAR at higher concentrations induced a significant down-regulation of fatty acid biosynthesis-associated genes in the bacteria, with the exception of an increased expression of fabA gene. The minimum inhibitory concentration (MIC) of NAR against these two bacteria was determined, and both of bacteria underwent morphological changes after exposure to 1.0 and 2.0 MIC.

The Versatile Effects of Dihydromyricetin in Health

Dihydromyricetin is a flavonoid isolated from Ampelopsis grossedentata, which is traditionally used in China. Dihydromyricetin exhibits health-benefiting activities with minimum adverse effects. Dihydromyricetin has been demonstrated to show antioxidative, anti-inflammatory, anticancer, antimicrobial, cell death-mediating, and lipid and glucose metabolism-regulatory activities. Dihydromyricetin may scavenge ROS to protect against oxidative stress or potentiate ROS generation to counteract cancer cells selectively without any effects on normal cells. However, the low bioavailability of dihydromyricetin limits its potential applications. Recent research has gained positive and promising data. This review will discuss the versatile effects and clinical prospective of dihydromyricetin.

Dihydromyricetin ameliorates atherosclerosis in LDL receptor deficient mice

BACKGROUND AND AIMS

Dihydromyricetin, the most abundant flavonoid in Ampelopsis grossedentata, exerts numerous pharmacological activities, including anti-inflammatory, antioxidant, hepatoprotective, and lipid regulatory activities; however, its protective effect against atherosclerosis remains poorly understood. The aim of the present study was to evaluate the effects of dihydromyricetin on high fat diet (HFD)-induced atherosclerosis using LDL receptor deficient (LDLr^-/-) mice.

METHODS

Blood samples were collected for determination of serum lipid profiles, oxidized LDL (ox-LDL) and pro-inflammatory cytokines. Histology, hepatic lipid content, quantification of atherosclerosis, assessment of oxidative stress and inflammation were performed on liver and aorta samples by molecular biology methods. The effects of dihydromyricetin on ox-LDL-induced human umbilical vein endothelial cells (HUVECs) dysfunction and foam cell formation were further studied.

RESULTS

(1) Dihydromyricetin ameliorated hyperlipidemia, reduced serum ox-LDL, IL-6 and TNF-α levels in HFD-fed LDLr^-/- mice. Moreover, (2) dihydromyricetin suppressed hepatic lipid accumulation and increased protein expressions of PPARα, LXRα and ABCA1. (3) It inhibited atherosclerotic lesion formation and favoured features of plaque stability. (4) Dihydromyricetin prevented hepatic and aortic inflammation as evidenced by the reduced IL-6 and TNF-α mRNA expression; (5) it prevented hepatic and aortic oxidative stress by normalizing activities of antioxidant enzymes in the liver and suppressing reactive oxygen species generation and NOX2 protein expression in both liver and aorta; (6) it inhibited oxLDL-induced injury, monocytes adhesion and oxidative stress in HUVECs and (7) inhibited macrophage foam cell formation and enhanced cholesterol efflux.

CONCLUSIONS

These findings suggest that dihydromyricetin could reduce atherosclerosis via its pleiotropic effects, including improvement of endothelial dysfunction, inhibition of macrophage foam cell formation, amelioration of lipid profiles, anti-inflammatory action and anti-oxidative effect.

Membrane and genomic DNA dual-targeting of citrus flavonoid naringenin against Staphylococcus aureus

Naringenin exerts its antibacterial action by disruption of the cytoplasmic membrane and DNA targeting effects inStaphylococcus aureus.