Antimicrobial activity of natural products from the flora of Northern Ontario, Canada

Can Gentisic Acid Serve as a High-Performance Antioxidant with Lower Toxicity for a Promising New Topical Application?

Gentisic acid (2,5-dihydroxybenzoic acid) is primarily found naturally in plants and has demonstrated a significant range of biological activities; however, its efficacy and safety as a topical application ingredient are not yet well established. Thus, the compound's potential antioxidant and antimicrobial properties were evaluated for efficacy, while the cytotoxicity was evaluated for safety. The antioxidant activity, measured by the DPPH kinetic method, showed an Efficiency Concentration (EC50) of 0.09 with an antioxidant reducing power (ARP) of 11.1. The minimum inhibitory concentration (MIC) against Staphylococcus aureus was 4.15 mg/mL, Escherichia coli was 4.00 mg/mL, Candida albicans was 3.00 mg/mL, and Cutibacterium acnes was 3.60 mg/mL, and the MIC for C. acnes has remained unpublished until now. The substance showed low cytotoxicity by the neutral red uptake (NRU) methodology against HaCat, HDFa, and HepG2 cells at concentrations of up to 10.0, 7.3, and 4.0 mM, respectively, also representing unpublished data. This evidence demonstrates gentisic acid as a promising active substance for skin topical application in the cosmetic or pharmaceutical industry.

Gut Microbiome Composition Is Associated With Future Onset of Crohn's Disease in Healthy First-Degree Relatives

BACKGROUND & AIMS

The cause of Crohn's disease (CD) is unknown, but the current hypothesis is that microbial or environmental factors induce gut inflammation in genetically susceptible individuals, leading to chronic intestinal inflammation. Case-control studies of patients with CD have cataloged alterations in the gut microbiome composition; however, these studies fail to distinguish whether the altered gut microbiome composition is associated with initiation of CD or is the result of inflammation or drug treatment.

METHODS

In this prospective cohort study, 3483 healthy first-degree relatives (FDRs) of patients with CD were recruited to identify the gut microbiome composition that precedes the onset of CD and to what extent this composition predicts the risk of developing CD. We applied a machine learning approach to the analysis of the gut microbiome composition (based on 16S ribosomal RNA sequencing) to define a microbial signature that associates with future development of CD. The performance of the model was assessed in an independent validation cohort.

RESULTS

In the validation cohort, the microbiome risk score (MRS) model yielded a hazard ratio of 2.24 (95% confidence interval, 1.03-4.84; P = .04), using the median of the MRS from the discovery cohort as the threshold. The MRS demonstrated a temporal validity by capturing individuals that developed CD up to 5 years before disease onset (area under the curve > 0.65). The 5 most important taxa contributing to the MRS included Ruminococcus torques, Blautia, Colidextribacter, an uncultured genus-level group from Oscillospiraceae, and Roseburia.

CONCLUSION

This study is the first to demonstrate that gut microbiome composition is associated with future onset of CD and suggests that gut microbiome is a contributor in the pathogenesis of CD.

Synergistic Activity of Thymol with Commercial Antibiotics against Critical and High WHO Priority Pathogenic Bacteria

The use of synergistic combinations between natural compounds and commercial antibiotics may be a good strategy to fight against microbial resistance, with fewer side effects on human, animal and environmental, health. The antimicrobial capacity of four compounds of plant origin (thymol and gallic, salicylic and gentisic acids) was analysed against 14 pathogenic bacteria. Thymol showed the best antimicrobial activity, with MICs ranging from 125 µg/mL (for Acinetobacter baumannii, Pasteurella aerogenes, and Salmonella typhimurium) to 250 µg/mL (for Bacillus subtilis, Klebsiella aerogenes, Klebsiella pneumoniae, Serratia marcescens, Staphylococcus aureus, and Streptococcus agalactiae). Combinations of thymol with eight widely used antibiotics were studied to identify combinations with synergistic effects. Thymol showed synergistic activity with chloramphenicol against A. baumannii (critical priority by the WHO), with streptomycin and gentamicin against Staphylococcus aureus (high priority by the WHO), and with streptomycin against Streptococcus agalactiae, decreasing the MICs of these antibiotics by 75% to 87.5%. The kinetics of these synergies indicated that thymol alone at the synergy concentration had almost no effect on the maximum achievable population density and very little effect on the growth rate. However, in combination with antibiotics at the same concentration, it completely inhibited growth, confirming its role in facilitating the action of the antibiotic. The time-kill curves indicated that all the combinations with synergistic effects were mainly bactericidal.

Bioassay-Guided Isolation of Antimicrobial Components and LC/QToF Profile of Plumeria obtusa: Potential for the Treatment of Antimicrobial Resistance

The methanolic fraction (M-F) of the total extract (TE) of Plumeria obtusa L. aerial parts showed promising antibacterial effects against the MDR (multidrug-resistant) gram-negative pathogens Klebsiella pneumoniae and Escherichia coli O157:H7 [Shiga toxin-producing E. coli (STEC)]. In addition, M-F had a synergistic effect (in combination with vancomycin) against the MDR gram-positive strains MRSA (methicillin-resistant Staphylococcus aureus) and Bacillus cereus. After treating the K. pneumoniae- and STEC-infected mice with M-F (25 mg/kg, i.p.), the level of IgM and TNF-α was decreased and the severity of pathological lesions were reduced better than that observed after administration of gentamycin (33 mg/kg, i.p.). Thirty-seven compounds including 10 plumeria-type iridoids and 18 phenolics, 7 quinoline derivatives, 1 amino acid, and 1 fatty acid were identified in TE using LC/ESI-QToF. Furthermore, five compounds; kaempferol 3-O-rutinoside (M1), quercetin 3-O-rutinoside (M2), glochiflavanoside B (M3), plumieride (M4), and 13-O-caffeoylplumieride (M5) were isolated from M-F. M5 was active against K. pneumoniae (MIC of 64 μg/mL) and STEC (MIC of 32 μg/mL). These findings suggested that M-F and M5 are promising antimicrobial natural products for combating MDR K. pneumoniae and STEC nosocomial infections.

A systematic review of antibacterial activity of polyphenolic extract from date palm (Phoenix dactylifera L.) kernel

Background: Emergence of antibiotic-resistant bacteria makes exploration of natural antibacterial products imperative. Like other fruit processing industry by-products, date kernels, a waste from date processing industry is rich in its extractable polyphenols. The rich polyphenolic content suggests that date kernel extracts (DKE) can be a cost-effective source of antimicrobial agents, however, their antibacterial activity is poorly understood. Hence, a systematic review of available literature to establish DKE's antibacterial activity is warranted. Methods: A systematic PRISMA approach was employed, and relevant studies were identified using defined keywords from Google Scholar, Scopus, PubMed, and Web of Science databases. The search results were screened based on predefined eligibility criteria and data extraction, organization, pooling, and descriptive statistical analyses of original research records conducted. Results: A total of 888 published records were retrieved from databases. Preliminary screening by applying specific eligibility criteria reduced records to 96 which after full text screening further decreased to 14 records. Escherichia coli and Staphylococcus aureus were the most studied organisms. Results indicate moderate to highly active effect shown by the less polar solvent based DKE's against Gram-positive and by the aqueous based DKE's against Gram-negative bacteria. The review confirms antibacterial activity of DKE against both Gram-positive and -negative bacteria. Heterogeneity in reported polyphenolic content and antibacterial activity are due to differences in cultivars, extraction methods, test methods, model organisms, etc. Use of standardized protocols for isolation, characterization, testing of DKE's active polyphenols to elucidate its antibacterial activity is recommended to establish the clinical efficacy of natural antibacterial compounds from DKE. Conclusion: This review outlines the current knowledge regarding antibacterial activity of polyphenolic DKE, identifying gaps in information and provides key recommendations for future research directions.

Fraxinol Stimulates Melanogenesis in B16F10 Mouse Melanoma Cells through CREB/MITF Signaling

Melanin pigment produced in melanocytes plays a protective role against ultraviolet radiation. Selective destruction of melanocytes causes chronic depigmentation conditions such as vitiligo, for which there are very few specific medical treatments. Here, we found that fraxinol, a natural coumarin from Fraxinus plants, effectively stimulated melanogenesis. Treatment of B16-F10 cells with fraxinol increased the melanin content and tyrosinase activity in a concentration-dependent manner without causing cytotoxicity. Additionally, fraxinol enhanced the mRNA expression of melanogenic enzymes such as tyrosinase, tyrosinase-related protein-1, and tyrosinase-related protein-2. Fraxinol also increased the expression of microphthalmia-associated transcription factor at both mRNA and protein levels. Fraxinol upregulated the phosphorylation of cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB). Furthermore, H89, a cAMP-dependent protein kinase A inhibitor, decreased fraxinol-induced CREB phosphorylation and microphthalmia-associated transcription factor expression and significantly attenuated the fraxinol-induced melanin content and intracellular tyrosinase activity. These results suggest that fraxinol enhances melanogenesis via a protein kinase A-mediated mechanism, which may be useful for developing potent melanogenesis stimulators.

Design, synthesis and characterization of lysozyme-gentisic acid dual-functional conjugates with antibacterial/antioxidant activities

Both microbiological and chemical food spoilages remain to be the major challenges in the food industry's efforts to combat food waste and loss because of the lack of high efficacy food preservatives. In this study, dual-functional conjugates that simultaneously suppress both lipid oxidation and microorganism growth are fabricated by covalently conjugating natural antioxidant gentisic acid (GA) on native antibacterial lysozyme (Lys). The mixing ratio of Lys and GA determines the particle size, morphology, antioxidant activity, and antimicrobial performance of the ensuing conjugates. With more of GA being grafted, a drastic decrease in the net surface charge with the concomitant occurrence of aggregations are observed in the conjugates. The maximum antioxidant activity and antibacterial performance of the conjugates is achieved when Lys:GA molar ratio is 1:112. The findings could guide the rational design of future functional food ingredients that combine multiple natural bioactive compounds to effectively intervene food waste and loss.

Design of Oleanolic Acid-based Hybrid Compounds as Potential Pharmaceutical Scaffolds

Background:

Infectious diseases, as well as cancer, are the leading causes of death worldwide. Drug resistance usually results in their treatment requiring a combination of two or more drugs.

Objective:

Oleanolic-based hybrid compounds were prepared via esterification and characterized using FTIR, NMR and LC-MS. In vitro antibacterial and in vitro cytotoxicity studies were performed.

Method:

Oleanolic acid was hybridized with selected known pharmaceutical scaffolds via the carboxylic acid functionality in order to develop therapeutics with increased biological activity. Antibacterial activity was determined using the micro-dilution assay against selected Gram-positive and Gram-negative bacteria and cytotoxicity using the sulforhodamine B assay.

Results:

Compound 8 displayed potent antibacterial effect against five strains of bacteria, such as Bacillus subtilis, Staphylococcus aureus, Proteus vulgaris, Klebsiella oxytoca, and Escherichia coli, with MIC values of 1.25, 0.078, 0.078, 1.25, 1.25 mg/mL when compared to the control, oleanolic acid (MIC = 2.5 mg/mL). Furthermore, in vitro cytotoxicity, as determined using the SRB assay, against selected cancer cells revealed that compound 7 was the most cytotoxic on MDA, DU145, and MCF-7 cell lines with IC50 values of 69.87 ± 1.04, 73.2 ± 1.08, and 85.27 ± 1.02 μg/mL, respectively, compared to oleanolic acid with an IC50 > 200 μg/mL.

Conclusion:

Hybridization of oleanolic acid was successful, and further development of these potential antibacterial compounds with reduced cytotoxicity is therefore warranted.

Natural Compounds With Antimicrobial and Antiviral Effect and Nanocarriers Used for Their Transportation

Due to the increasing prevalence of life-threatening bacterial, fungal and viral infections and the ability of these human pathogens to develop resistance to current treatment strategies, there is a great need to find and develop new compunds to combat them. These molecules must have low toxicity, specific activity and high bioavailability. The most suitable compounds for this task are usually derived from natural sources (animal, plant or even microbial). In this review article, the latest and most promising natural compounds used to combat bacteria, filamentous fungi and viruses are presented and evaluated. These include plant extracts, essential oils, small antimicrobial peptides of animal origin, bacteriocins and various groups of plant compounds (triterpenoids; alkaloids; phenols; flavonoids) with antimicrobial and antiviral activity. Data are presented on the inhibitory activity of each natural antimicrobial substance and on the putative mechanism of action against bacterial and fungal strains. The results show that among the bioactive compounds studied, triterpenoids have significant inhibitory activity against coronaviruses, but flavonoids have also been shown to inhibit SARS-COV-2. The last chapter is devoted to nanocarriers used to improve stability, bioavailability, cellular uptake/internalization, pharmacokinetic profile and reduce toxicity of natural compunds. There are a number of nanocarriers such as liposomes, drug delivery microemulsion systems, nanocapsules, solid lipid nanoparticles, polymeric micelles, dendrimers, etc. However, some of the recent studies have focused on the incorporation of natural substances with antimicrobial/antiviral activity into polymeric nanoparticles, niosomes and silver nanoparticles (which have been shown to have intrinsic antimicrobial activity). The natural antimicrobials isolated from animals and microorganisms have been shown to have good inhibitory effect on a range of pathogens, however the plants remain the most prolific source. Even if the majority of the studies for the biological activity evaluation are in silico or in vitro, their internalization in the optimum nanocarriers represents the future of “green therapeutics” as shown by some of the recent work in the field.

Chemical, antioxidant and cytotoxic profile of hydroalcoholic extracts of plants from Southern Brazil and their activity against pathogenic fungi isolated from dogs and cats with sensitivity and resistance to conventional antifungals

We aimed to evaluate the chemical, antioxidant, cytotoxic, and antifungal activities of hydroalcoholic extracts of native plants from Southern Brazil: Schinus terebinthifolia (SCH), Persicaria hydropiperoides (PER), Eugenia uniflora (EUG) and Equisetum hyemale (EQU). Ethyl gallate, quercetin, and quinic acid were prevalent compounds identified by LC-MS. For total phenolic/flavonoid contents and the antioxidant potential against ABTS/DPPH radicals, the ascending order was EQU < PER < EUG < SCH. All extracts were low cytotoxic and kept a high Vero cell viability (>75%) at concentrations up to 12.5 mg/mL (MTT assay). By M38-A2/M27-A3 (CLSI) against 68 clinical isolates of animals and strains of Malassezia pachydermatis, Sporothrix brasiliensis, Microsporum canis, Microsporum gypseum and Trichophyton mentagrophytes, all extracts (MIC/MFC ≤3.13-100 mg/mL) were active, except EUG. SCH inhibited and killed S. brasiliensis (MIC/MFC_50/90 3.12-12.5 mg/mL) and dermatophytes (MIC/MFC 6.25-25 mg/mL) resistant to ketoconazole and itraconazole. These findings support the promising use of the selected plant extracts as antifungal agents.

In vitro and in vivo investigation of polypharmacology of propolis extract as anticancer, antibacterial, anti-inflammatory, and chemical properties

Numerous compounds derived from natural sources such as microbes, plants, and insects have proven to be safe, efficacious, and cost-effective therapeutics for human diseases. This study examined the bioactivities of propolis, a structural sealant and antibacterial/antifungal agent produced by honey bees. Chinese propolis was extracted in methanol or hexane. Propolis significantly reduced the numbers of viable cancer cells when applied as a methanol extract (IC50 values in μg/mL for the indicated cell line: MDA-MB-231, 74.12; LoVo, 74.12; HepG2, 77.74; MCF7, 95.10; A549, 114.84) or a hexane extract (MDA-MB-231, 52.11; LoVo, 45.9; HepG2, 52.11; MCF7, 78.01; A549, 67.90). Hexane extract also induced apoptosis of HepG2 cells according to activated caspase-3/7 expression assays (17.6 ± 2.9% at 150 μg/mL and 89.2 ± 1.9% at 300 μg/mL vs 3.4 ± 0.4% in vehicle control), suppressed the growth of Candida albicans and multiple multidrug-resistant and nonresistant Gram-positive bacteria, and inhibited croton oil-induced skin inflammation when applied as topical treatment. GC-MS identified hexadecanoic acid methyl ester as a major constituent (33.6%). Propolis hexane extract has potential anticancer, antimicrobial, and anti-inflammatory activities.

A review on phyto-pharmacology of Oxalis corniculata

Oxalis corniculata (Oxalidaceae) is a small decumbent and delicate appearing medicinal herb flourishing in warm temperate and tropical domains such as Pakistan and India. Main bioactive chemical constituents of Oxalis plant include several alkaloids, flavonoids, terpenoids, cardiac glycosides, saponins, phlobatannins along with steroids. Due to its polyphenolic, glycosides and flavonoid profile, it is proved to be protective in numerous ailments and exhibit various biological activities such as anti-fungal, anti-cancer, anti-oxidant, anti-bacterial, anti-diabetic, and cardioprotective. Moreover, bioactive phytochemicals from this plant possess significant wound healing potential. Our current effort intends to emphasize on the immense significance of this plant species, which have not been the subject matter of clinical trials and effective pharmacological studies, even though its favored usage has been stated. This review proposes that Oxalis corniculata possess potential for the cure of various diseases, however, further researches on isolation and characterization of bioactive compounds along with pre-clinical trials are compulsory to figure out its pharmacological applications.

Banana plant as a source of valuable antimicrobial compounds and its current applications in the food sector

Bananas (Musaceae) are one of the world's most common fruit crops and the oldest medicinal plants that are used to treat a variety of infections. There has been recent interest in elucidating the efficiency of the naturally active ingredients, particularly the antimicrobials, in this plant. This review begins with a short background of the banana plant and its cultivars as well as a brief description of its parts. Different experimental tests of the antimicrobial effects and the responsible bioactive compounds of the banana part extracts are then elaborated. A variety of recent and evolving applications of banana parts in the development of functional bakery, dairy, beverage, and meat products as a wheat substitute, fiber/prebiotic source, fat/sucrose substitute, and natural antioxidant are also discussed. Finally, the recent challenges and opportunities presented by different banana parts in creating bio-packaging materials and bactericidal nanoparticles are addressed. This plant contains a variety of antimicrobial substances, including dopamine, gentisic acid, ferulic acid, lupeol, and 3-carene. However, few studies have been conducted on its use as a bio-preservative in food products; it should also be seen as a natural source of both antimicrobial and antioxidant agents. It offers a potentially simple eco-friendly alternative to antibacterial and fungicidal agents rather than chemicals. Low cost, reliable methods for purifying these compounds from banana waste could be useful for food storage and creating more value-added bio-packaging products for perishable food goods.

Selenium Nanoparticles as Candidates for Antibacterial Substitutes and Supplements against Multidrug-Resistant Bacteria

In recent years, multidrug-resistant (MDR) bacteria have increased rapidly, representing a major threat to human health. This problem has created an urgent need to identify alternatives for the treatment of MDR bacteria. The aim of this study was to identify the antibacterial activity of selenium nanoparticles (SeNPs) and selenium nanowires (SeNWs) against MDR bacteria and assess the potential synergistic effects when combined with a conventional antibiotic (linezolid). SeNPs and SeNWs were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), zeta potential, and UV-visible analysis. The antibacterial effects of SeNPs and SeNWs were confirmed by the macro-dilution minimum inhibitory concentration (MIC) test. SeNPs showed MIC values against methicillin-sensitive S. aureus (MSSA), methicillin-resistant S. aureus (MRSA), vancomycin-resistant S. aureus (VRSA), and vancomycin-resistant enterococci (VRE) at concentrations of 20, 80, 320, and >320 μg/mL, respectively. On the other hand, SeNWs showed a MIC value of >320 μg/mL against all tested bacteria. Therefore, MSSA, MRSA, and VRSA were selected for the bacteria to be tested, and SeNPs were selected as the antimicrobial agent for the following experiments. In the time-kill assay, SeNPs at a concentration of 4X MIC (80 and 320 μg/mL) showed bactericidal effects against MSSA and MRSA, respectively. At a concentration of 2X MIC (40 and 160 μg/mL), SeNPs showed bacteriostatic effects against MSSA and bactericidal effects against MRSA, respectively. In the synergy test, SeNPs showed a synergistic effect with linezolid (LZD) through protein degradation against MSSA and MRSA. In conclusion, these results suggest that SeNPs can be candidates for antibacterial substitutes and supplements against MDR bacteria for topical use, such as dressings. However, for use in clinical situations, additional experiments such as toxicity and synergistic mechanism tests of SeNPs are needed.

4-Ethoxybenzoic acid inhibits Staphylococcus aureus biofilm formation and potentiates biofilm sensitivity to vancomycin

The adverse health effects of Staphylococcus aureus biofilm infections coupled with an increased global prevalence of antibiotic resistance highlight the need for novel anti-pathogenic, anti-biofilm compounds. The authors recently determined that ethyl-4-ethoxybenzoic acid (EEB) had anti-pathogenic, anti-biofilm activity. Based on this finding, a structure-activity analysis was undertaken to identify more effective compounds. Microtitre crystal violet assays followed by plate counts were conducted to measure the dose-dependent anti-biofilm and antimicrobial activities of 13 phenolic compounds related to EEB. By displaying these characteristics on a two-component plot, 4-ethoxybenzoic acid (4EB) and methyl gallate were identified as two anti-pathogenic, anti-biofilm compounds of interest. To characterize their mechanisms of activity, their effects on cell hydrophobicity, hemolysis activity, membrane integrity, extracellular polymeric substance production and vancomycin sensitivity were examined. Both 4EB and methyl gallate inhibited up to 87% of biofilm formation with minimal impact on the viability of stationary-phase cells or bacterial growth. Combination treatments of 4EB and vancomycin decreased the viability of biofilm-dwelling cells by up to 85% compared with vancomycin alone, indicating a synergistic effect. Methyl gallate did not potentiate vancomycin. 4EB decreased the percentage of hydrophobic cells in culture from 78% to 49%, indicating that 4EB may prevent biofilm formation by altering cell membrane hydrophobicity. These findings suggest that 4EB has potential as an anti-pathogenic, anti-biofilm agent for the prevention of S. aureus biofilms, or as a treatment for established biofilms when combined with antibiotics.

Novel effective antibacterial small-molecules against Staphylococcus and Enterococcus strains

Background: Resistance developments against established antibiotics are an emerging problem for antibacterial therapies. Novel antibiotics are urgently needed. Materials & methods: We developed novel small-molecule antibacterials which are easily accessible in a simple one-pot synthesis. The central cyclopentaindole core is substituted with two indole residues. Various indole and cyclopentane substituents have been introduced. Additionally, first indole substituted propene compounds as ring-open variants of the cyclopentaindoles have been yielded and evaluated as antibacterials against Staphylococcus aureus and Enterococcus strains. Results: Most effective compounds have been those with a bromo cyclopentane and a chloro indole substitution. First lead compounds were identified with promising activities similar to that observed in vitro for last resort antibiotics, so that the novel compounds enriche the pool of perspective small-molecule antibacterial drug candidates.

Comparative Studies of Fraxinus Species from Korea Using Microscopic Characterization, Phytochemical Analysis, and Anti-Lipase Enzyme Activity

Fraxinus species belongs to the Oleaceae family, commonly known as Ash tree, and has been utilized as a folk medicine with various medicinal properties, including anti-obesity activity. The goal of the present study was to establish quality control parameters using microscopic characterization, phytochemical differentiation, and anti-lipase activity evaluation of five Fraxinus plants in Korea. Microscopic evaluation of the lower surface, petiole, and midrib of leaves, and stem bark showed discriminative anatomical characteristics, such as the stomatal index of the lower leaf surface; the number of sclerenchyma cells, and the diameter of parenchyma cells in the petiole and midrib; and the cork cell size and fiber frequency in the stem bark. Phytochemical analysis using high-performance liquid chromatography revealed the significant variation in the chemical profiles of the 12 major secondary metabolites among the samples. The orthogonal projections to latent structure-discrimination analysis efficiently differentiated each group belonging to each Fraxinus plant with the anatomical and quantification data. F. rhynchophylla and ligstroside showed the most potent anti-lipase activity among the plants and the 12 major metabolites, respectively. These findings could serve as the scientific criteria for the appropriate identification and establishment of standards for the use of Fraxinus species as medicinal plants.

Phytochemical Diversity and Pharmacological Properties of Rhus coriaria

Rhus coriaria L. (Anacardiaceae), sumac, is a common condiment, appetizer and souring agent in the Mediterranean region that has a long history in traditional medicine. R. coriaria has been prescribed for the treatment of many ailments including diarrhea, ulcer, hemorrhoids, hemorrhage, wound healing, hematemesis, and eye ailments like ophthalmia and conjunctivitis. The plant is also used as diuresis, antimicrobial, abortifacient and as a stomach tonic. Sumac is known to be rich in different classes of phytochemicals including tannins, polyphenols, flavonoids, organic acids and essential oils and continues to be a hot topic for extensive research work designed for revealing its phytochemical constituents and evaluating its bioactive properties. This review summarizes the recent phytochemical and diverse bioactivity studies on R. coriaria, especially those concerned with antitumor, antioxidant, hypoglycemic, antimicrobial, and anti-inflammatory studies.

In Vitro Antibacterial and Antiproliferative Potential of Echinops lanceolatus Mattf. (Asteraceae) and Identification of Potential Bioactive Compounds

Many species belonging to the genus Echinops are widely used in traditional medicine to treat infectious diseases and cancers. The present study aimed to evaluate the antibacterial and antiproliferative properties of Echinops lanceolatus Mattf. (Asteraceae). The activity of the methanolic extract and subsequent partition fractions was investigated against drug-resistant bacteria (Gram-negative and Gram-positive) and human tumor cell lines using broth microdilution and sulforhodamine B (SRB) assay, respectively. Our findings revealed weak to moderate antibacterial activities of tested extracts, with the recorded minimal inhibitory concentrations ranging from 256 to 1024 µg/mL. The ethyl acetate fraction (EL-EA) was found to be the most effective. Likewise, that fraction displayed strong antiproliferative potential with recorded IC50 of 8.27 µg/mL and 28.27 µg/mL on A549 and HeLa cells, respectively. An analysis based on the ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) of the EL-EA fraction allowed the identification of 32 compounds, of which quinic acid and derivatives, cinnamic acid derivatives, dihydrokaempferol, naringenin-7-O-glucoside, apigenin-7-O-d-glucoside, naringin, apigenin, rhoifolin, coniferyl aldehyde, and secoisolariciresinol are well-known compounds of biological importance. This study is first to report on the biological activity and phytochemical profile of E. lanceolatus. We provide a baseline to consider E. lanceolatus as a valuable source of anti-infective and antiproliferative agents.

Antimicrobial activity and chemical composition of white birch (Betula papyrifera Marshall) bark extracts

Extracts from white birch have been reported to possess antimicrobial properties, but no study has linked the chemical composition of bark extract with antimicrobial activity. This study aimed to identify white birch (Betula papyrifera Marshall) bark extracts with antimicrobial activity and elucidate its composition. In order to obtain the highest extraction yield, bark residues >3 mm were retained for extraction. A total of 10 extraction solvents were used to determine the extraction yield of each of them. Methanol and ethanol solvents extracted a greater proportion of molecules. When tested on eight microorganism species, the water extract proved to have the best antimicrobial potential followed by the methanol extract. The water extract inhibited all microorganisms at low concentration with minimal inhibitory concentration between 0.83 and 1.67 mg/ml. Using ultraperformance liquid chromatography coupled to a time-of-flight quadrupole mass spectrometer, several molecules that have already been studied for their antimicrobial properties were identified in water and methanol extracts. Catechol was identified as one of the dominant components in white birch bark water extract, and its antimicrobial activity has already been demonstrated, suggesting that catechol could be one of the main components contributing to the antimicrobial activity of this extract. Thus, extractives from forestry wastes have potential for new applications to valorize these residues.

El-Ansary D. Mammillaria Species-Polyphenols Studies and Anti-Cancer, Anti-Oxidant, and Anti-Bacterial Activities

Discovering new natural resources of polyphenols is the aim of many recent studies in the field of natural product research. This study tentatively investigated the polyphenols profile of the stems of seven Mammillaria species (M. rhodantha, M. spinosissima, M. hahniana, M. crucigera, M. candida, M. albilanata, and M. muehlenpfordtii) using high performance liquid chromatography with DAD detector (HPLC-DAD) method. Furthermore, the anti-cancer, anti-oxidant, and anti-bacterial potentials of these extracts as well as major identified phenols were explored. The HPLC-DAD study confirmed the availability of six phenolic acids, including gentisic acid, chlorogenic acid, caffeic acid, protocatechuic acid, sinapic acid, and p-hydroxybenzoic acid. The dominant compounds were: gentisic acid in M. rhodantha and M. spinosissima; chlorogenic acid in M. muehlenpfordtii, M. crucigera, and M. rhodantha; and caffeic acid in M. rhodantha, M. crucigera, and M. spinosissima. Stems of Mammillaria sp. showed antiproliferative effects against HeLa, MCF-7, and Jurkat cells. In HeLa and MCF-7 cells, the best antiproliferative activities were found in the treatments with M. rhodantha, M. spinosissima, and M. muehlenpfordtii. The apoptotic assay of M. rhodantha, M. spinosissima, and M. muehlenpfordtii showed accumulation of necrotic cells in the early and late apoptotic phase. M. rhodantha, M. spinosissima, and M. muehlenpfordtii showed the highest anti-oxidant activities using 2,2-diphenyl-1-picrylhydrazyl (DPPH), β-carotene bleaching, and ferric reducing anti-oxidant power (FRAP) assays. M. rhodantha was the best source of antioxidants. Mammillaria sp. showed moderate anti-bacterial effects against bacteria and the highest effects were found using the extracts of M. rhodantha, M. spinosissima, M. crucigera and M. muehlenpfordtii against most bacteria. The anti-bacterial activities were attributed to other phenolic compounds (e.g., chlorogenic acid) than gentisic acid, which was not active against most bacteria. Mammillaria sp. could be considered to be an important natural source of phenolic acids with anti-cancer, anti-bacterial, and anti-oxidant activities.

A review on gentisic acid as a plant derived phenolic acid and metabolite of aspirin: Comprehensive pharmacology, toxicology, and some pharmaceutical aspects

Beneficial therapeutic effects of phenolic acids have been proven in various research projects including in vivo and in vitro studies. Gentisic acid (GA) is a phenolic acid that has been associated with useful effects on human health, such as antiinflammatory, antigenotoxic, hepatoprotective, neuroprotective, antimicrobial, and especially antioxidant activities. It is an important metabolite of aspirin and also widely distributed in plants as a secondary plant product such as Gentiana spp., Citrus spp., Vitis vinifera, Pterocarpus santalinus, Helianthus tuberosus, Hibiscus rosa-sinensis, Olea europaea, and Sesamum indicum and in fruits such as avocados, batoko plum, kiwi fruits, apple, bitter melon, black berries, pears, and some mushrooms. This study was undertaken to review the pharmacological effects, pharmacokinetic properties as well as toxicity and pharmaceutical applications of GA.

Antibacterial Activity and Mechanism of Action of Aspidinol Against Multi-Drug-Resistant Methicillin-Resistant Staphylococcus aureus

This study aimed at investigating the antibacterial activity of aspidinol, an extract from Dryopteris fragrans (L.) Schott, against methicillin-resistant Staphylococcus aureus (MRSA). MRSA isolates were treated with aspidinol to determine the differential expression of genes and associated pathways following the drug treatment. Aspidinol displayed significant anti-MRSA activity, both in vivo (minimum inhibitory concentration = 2 μg/mL) and in vitro, and achieved an antibacterial effect comparable to that of vancomycin. In the lethal septicemic mouse study, a dose of 50 mg/kg of either aspidinol or vancomycin provided significant protection from mortality. In the non-lethal septicemic mouse study, aspidinol and vancomycin produced a significant reduction in mean bacterial load in murine organs, including the spleen, lung, and liver. After treatment with aspidinol, we found through RNA-seq and RT-PCR experiments that the inhibition of the formation of ribosomes was the primary S. aureus cell-killing mechanism, and the inhibition of amino acid synthesis and the reduction of virulence factors might play a secondary role.

Fraxinus: A Plant with Versatile Pharmacological and Biological Activities

Fraxinus, a member of the Oleaceae family, commonly known as ash tree is found in northeast Asia, north America, east and western France, China, northern areas of Pakistan, India, and Afghanistan. Chemical constituents of Fraxinus plant include various secoiridoids, phenylethanoids, flavonoids, coumarins, and lignans; therefore, it is considered as a plant with versatile biological and pharmacological activities. Its tremendous range of pharmacotherapeutic properties has been well documented including anticancer, anti-inflammatory, antioxidant, antimicrobial, and neuroprotective. In addition, its bioactive phytochemicals and secondary metabolites can be effectively used in cosmetic industry and as a competent antiaging agent. Fraxinus presents pharmacological effectiveness by targeting the novel targets in several pathological conditions, which provide a spacious therapeutic time window. Our aim is to update the scientific research community with recent endeavors with specifically highlighting the mechanism of action in different diseases. This potentially efficacious pharmacological drug candidate should be used for new drug discovery in future. This review suggests that this plant has extremely important medicinal utilization but further supporting studies and scientific experimentations are mandatory to determine its specific intracellular targets and site of action to completely figure out its pharmacological applications.

Sinapic Acid Affects Phenolic and Trichothecene Profiles of F. culmorum and F. graminearum Sensu Stricto

Plant-derived compounds for reducing the mycotoxin load in food and feed have become a rapidly developing research field of importance for plant breeding efforts and in the search for natural fungicides. In this study, toxigenic strains of Fusarium culmorum and F. graminearum sensu stricto were exposed to sinapic acid on solid YES media at levels close to those reported in wheat bran. Fusaria produced phenolic acids, whose accumulation was decreased by exogenous sinapic acid. Strains exposed to the lowest doses of sinapic acid showed more efficient reduction of phenolic acid production than fungi kept at higher concentrations of this compound. Fungi reduced exogenous sinapic acid, leading to the formation of syringic aldehyde. Treatment with sinapic acid led to a dramatic accumulation of its parent compound ferulic acid, presumably due to inhibition of the further conversion of this phenolic compound. Exogenous sinapic acid decreased the production of trichothecenes by fungi. Higher doses of sinapic acid resulted in more efficient reduction of mycotoxin accumulation in the media. Gene expression studies of Tri genes responsible for trichothecene biosynthesis (Tri4, Tri5 and Tri10) proved that the inhibition of mycotoxin production by sinapic acid occurred at the transcriptional level. Fusaria respond to sinapic acid by stimulation of ergosterol biosynthesis.

Comparison of the XTT and resazurin assays for quantification of the metabolic activity of Staphylococcus aureus biofilm

We assessed whether resazurin was as efficient as XTT in the measurement of the metabolic activity of 209 clinical Staphylococcus aureus biofilm using an vitro model comparing the percentage of formazan and resorufin. The overall categorical agreement was 61.2% (r=0.024), which means that resazurin can not substitute XTT.

Natural product HTP screening for antibacterial (E.coli 0157:H7) and anti-inflammatory agents in (LPS from E. coli O111:B4) activated macrophages and microglial cells; focus on sepsis

Background

Acute systemic inflammatory response syndrome arising from infection can lead to multiple organ failure and death, with greater susceptibility occurring in immunocompromised individuals. Moreover, sub-acute chronic inflammation is a contributor to the pathology of diverse degenerative diseases (Parkinson’s disease, Alzheimer’s disease and arthritis). Given the known limitations in Western medicine to treat a broad range of inflammatory related illness as well as the emergence of antibiotic resistance, there is a renewed interest in complementary and alternative medicines (CAMs) to achieve these means.

Methods

A high throughput (HTP) screening of >1400 commonly sold natural products (bulk herbs, cooking spices, teas, leaves, supplement components, nutraceutical food components, fruit and vegetables, rinds, seeds, polyphenolics etc.) was conducted to elucidate anti-inflammatory substances in lipopolysaccharide (LPS) (E. coli serotype O111:B4) monocytes: RAW 264.7 macrophages [peripheral], BV-2 microglia [brain]) relative to hydrocortisone, dexamethasone and L-N6-(1Iminoethyl)lysine (L-NIL). HTP evaluation was also carried out for lethal kill curves against E.coli 0157:H7 1x10⁶ CFU/mL relative to penicillin. Validation studies were performed to assess cytokine profiling using antibody arrays. Findings were corroborated by independent ELISAs and NO2–/iNOS expression quantified using the Griess Reagent and immunocytochemistry, respectively. For robust screening, we developed an in-vitro efficacy paradigm to ensure anti-inflammatory parameters were observed independent of cytotoxicity. This caution was taken given that many plants exert tumoricidal and anti-inflammatory effects at close range through similar signaling pathways, which could lead to false positives.

Results

The data show that activated BV-2 microglia cells (+ LPS 1μg/ml) release >10-fold greater IL-6, MIP1/2, RANTES and nitric oxide (NO2–), where RAW 264.7 macrophages (+ LPS 1μg/ml) produced > 10-fold rise in sTNFR2, MCP-1, IL-6, GCSF, RANTES and NO2–. Data validation studies establish hydrocortisone and dexamethasone as suppressing multiple pro-inflammatory processes, where L-NIL suppressed NO2–, but had no effect on iNOS expression or IL-6. The screening results demonstrate relative few valid hits with anti-inflammatory effects at < 250μg/ml for the following: Bay Leaf (Laurus nobilis), Elecampagne Root (Inula helenium), Tansy (Tanacetum vulgare),Yerba (Eriodictyon californicum) and Centipeda (Centipeda minima), Ashwagandha (Withania somnifera), Feverfew (Tanacetum parthenium), Rosemary (Rosmarinus officinalis), Turmeric Root (Curcuma Longa), Osha Root (Ligusticum porteri), Green Tea (Camellia sinensis) and constituents: cardamonin, apigenin, quercetin, biochanin A, eupatorin, (-)-epigallocatechin gallate (EGCG) and butein. Natural products lethal against [E. coli 0157:H7] where the LC₅₀ < 100 μg/ml included bioactive silver hydrosol-Argentyn 23, green tea (its constituents EGCG > Polyphenon 60 > (-)-Gallocatechin > Epicatechin > (+)-Catechin), Grapeseed Extract (Vitis vinifera), Chinese Gallnut (its constituents gallic acid > caffeic acid) and gallic acid containing plants such as Babul Chall Bark (Acacia Arabica), Arjun (Terminalia Arjuna) and Bayberry Root Bark (Morella Cerifera).

Conclusions

These findings emphasize and validate the previous work of others and identify the most effective CAM anti-inflammatory, antibacterial compounds using these models. Future work will be required to evaluate potential combination strategies for long-term use to prevent chronic inflammation and possibly lower the risk of sepsis in immunocompromised at risk populations.

Antibacterial Activities and Antibacterial Mechanism of Polygonum cuspidatum Extracts against Nosocomial Drug-Resistant Pathogens

Recently, drug resistance due to the extensive abuse and over-use of antibiotics has become an increasingly serious problem, making the development of alternative antibiotics a very urgent issue. In this study, the Chinese herbal medicine, Polygonum cuspidatum, was extracted with 95% ethanol and the crude extracts were further purified by partition based on solvent polarity. The antimicrobial activities of the extracts and fractions were determined by the disk diffusion and minimum inhibitory concentration (MIC) methods. The results showed that the ethyl ether fraction (EE) of the ethanol extracts possesses a broader antimicrobial spectrum and greater antimicrobial activity against all of the tested clinical drug-resistant isolates, with a range of MIC values between 0.1–3.5 mg/mL. The active extract showed complete inhibition of pathogen growth and did not induce resistance to the active components. In addition, according to scanning electron microscope observations, EE resulted in greater cell morphological changes by degrading and disrupting the cell wall and cytoplasmic membrane, whereby ultimately this cell membrane integrity damage led to cell death. In conclusion, the EE extracts from Polygonum cuspidatum may provide a promising antimicrobial agent for therapeutic applications against nosocomial drug-resistant bacteria.