Antimicrobial activity and cytotoxicity of the ethanol extract, fractions and eight compounds isolated from Eriosema robustum (Fabaceae)

Optimizing Bothropstoxin-I-Derived Peptides: Exploring the Antibacterial Potential of p-BthW

Antimicrobial peptides are an emerging class of antibiotics that present a series of advantageous characteristics such as wide structural variety, broad spectrum of activity, and low propensity to select for resistance. They are found in all classes of life as defense molecules. A group of peptides derived from the protein Bothropstoxin-I has been previously studied as an alternative treatment against multi-drug-resistant bacteria. The peptide p-BthTX-I (sequence: KKYRYHLKPFCKK) and its homodimer, linked by disulfide oxidation through the residues of Cys11 and the serum degradation product [sequence: (KKYRYHLKPFC)2], were evaluated and showed similar antimicrobial activity. In this study, we synthesized an analogue of p-BthTX-I that uses the strategy of Fmoc-Lys(Fmoc)-OH in the C-terminal region for dimerization and tryptophan for all aromatic amino acids to provide better membrane interactions. This analogue, named p-BthW, displayed potent antibacterial activity at lower concentrations and maintained the same hemolytic levels as the original molecule. Our assessment revealed that p-BthW has a quick in vitro bactericidal action and prolonged post-antibiotic effect, comparable to the action of polymyxin B. The mode of action of p-BthW seems to rely not only on membrane depolarization but also on necrosis-like effects, especially in Gram-negative bacteria. Overall, the remarkable results regarding the propensity to develop resistance reaffirmed the great potential of the developed molecule.

Anti Gram-Positive Bacteria Activity of Synthetic Quaternary Ammonium Lipid and Its Precursor Phosphonium Salt

Organic ammonium and phosphonium salts exert excellent antimicrobial effects by interacting lethally with bacterial membranes. Particularly, quaternary ammonium lipids have demonstrated efficiency both as gene vectors and antibacterial agents. Here, aiming at finding new antibacterial devices belonging to both classes, we prepared a water-soluble quaternary ammonium lipid (6) and a phosphonium salt (1) by designing a synthetic path where 1 would be an intermediate to achieve 6. All synthesized compounds were characterized by Fourier-transform infrared spectroscopy and Nuclear Magnetic Resonance. Additionally, potentiometric titrations of NH3+ groups 1 and 6 were performed to further confirm their structure by determining their experimental molecular weight. The antibacterial activities of 1 and 6 were assessed first against a selection of multi-drug-resistant clinical isolates of both Gram-positive and Gram-negative species, observing remarkable antibacterial activity of both compounds against Gram-positive isolates of Enterococcus and Staphylococcus genus. Further investigations on a wider variety of strains of these species confirmed the remarkable antibacterial effects of 1 and 6 (MICs = 4-16 and 4-64 µg/mL, respectively), while 24 h-time-killing experiments carried out with 1 on different S. aureus isolates evidenced a bacteriostatic behavior. Moreover, both compounds 1 and 6, at the lower MIC concentration, did not show significant cytotoxic effects when exposed to HepG2 human hepatic cell lines, paving the way for their potential clinical application.

Synthesis and Characterization of Paclitaxel-Loaded Silver Nanoparticles: Evaluation of Cytotoxic Effects and Antimicrobial Activity

Carrier system therapies based on combining cancer drugs with nanoparticles have been reported to control tumor growth and significantly reduce the side effects of cancer drugs. We thought that paclitaxel-loaded silver nanoparticles (AgNPs-PTX) were the right carrier to target cancer cells. We also carried out antimicrobial activity experiments as systems formed with nanoparticles have been shown to have antimicrobial activity. In our study, we used easy-to-synthesize and low-cost silver nanoparticles (AgNPs) with biocatalytic and photocatalytic advantages as drug carriers. We investigated the antiproliferative activities of silver nanoparticles synthesized by adding paclitaxel on MCF-7 (breast adenocarcinoma cell line), A549 (lung carcinoma cell line), C6 (brain glioma cell line) cells, and healthy WI-38 (fibroblast normal cell line) cell lines and their antimicrobial activities on 10 different microorganisms. The synthesized AgNPs and AgNPs-PTX were characterized by dynamic light scattering (DLS), scanning transmission electron microscopy, UV-visible spectroscopy, Fourier transform infrared spectroscopy, and X-ray spectroscopy. The nanoparticles were spherical in shape, with AgNPs ranging in size from 2.32 to 5.6 nm and AgNPs-PTXs from 24.36 to 58.77 nm. AgNPs demonstrated well stability of -47.3 mV, and AgNPs-PTX showed good stability of -25.4 mV. The antiproliferative effects of the synthesized nanoparticles were determined by XTT (tetrazolium dye; 2,3-bis-(2-methoxy-4-nitro-5-sulfenyl)-(2H)-tetrazolium-5-carboxanilide), and the proapoptotic effects were determined by annexin V/propidium iodide (PI) staining. The effect of AgNPs-PTX was more effective, and anticancer activity was higher than PTX in all cell lines. When selectivity indices were calculated, AgNPs-PTX was more selective in the A549 cell line (SI value 6.53 μg/mL). AgNPs-PTX was determined to increase apoptosis cells by inducing DNA fragmentation. To determine the antimicrobial activity, the MIC (minimum inhibitory concentration) test was performed using 8 different bacteria and 2 different fungi. Seven of the 10 microorganisms tested exhibited high antimicrobial activity according to the MIC ≤100 μg/mL standard, reaching MIC values below 100 μg/mL and 100 μg/mL for both AgNPs and AgNPs-PTX compared to reference sources. Compared to standard antibiotics, AgNPs-PTX was highly effective against 4 microorganisms.

Exploring the antiviral potential of justicidin B and four glycosylated lignans from Phyllanthus brasiliensis against Zika virus: A promising pharmacological approach

BACKGROUND

Zika virus (ZIKV) is an emerging arbovirus that in recent years has been associated with cases of severe neurological disorders, such as microcephaly in newborns and Guillain-Barré syndrome in adults. As there is no vaccine or treatment, the search for new therapeutic targets is of great relevance. In this sense, plants are extremely rich sources for the discovery of new bioactive compounds and the species Phyllanthus brasiliensis (native to the Amazon region) remains unexplored.

PURPOSE

To investigate the potential antiviral activity of compounds isolated from P. brasiliensis leaves against ZIKV infection.

METHODS

In vitro antiviral assays were performed with justicidin B (a lignan) and four glycosylated lignans (tuberculatin, phyllanthostatin A, 5-O-β-d-glucopyranosyljusticidin B, and cleistanthin B) against ZIKV in Vero cells. MTT colorimetric assay was used to assess cell viability and plaque forming unit assay to quantify viral load. In addition, for justicidin B, tests were performed to investigate the mechanism of action (virucidal, adsorption, internalization, post-infection).

RESULTS

The isolated compounds showed potent anti-ZIKV activities and high selectivity indexes. Moreover, justicidin B, tuberculatin, and phyllanthostatin A completely reduced the viral load in at least one of the concentrations evaluated. Among them, justicidin B stood out as the main active, and further investigation revealed that justicidin B exerts its antiviral effect during post-infection stages, resulting in a remarkable 99.9 % reduction in viral load when treatment was initiated 24 h after infection.

CONCLUSION

Our findings suggest that justicidin B inhibits endosomal internalization and acidification, effectively interrupting the viral multiplication cycle. Therefore, the findings shed light on the promising potential of isolated compounds isolated from P. brasiliensis, especially justicidin B, which could contribute to the drug development and treatments for Zika virus infections.

Bioprospecting the potential of metabolites from a Saharan saline soil strain Nocardiopsis dassonvillei GSBS4

Saharan soil samples collected in El-Oued province have been investigated for actinobacteria as a valuable source for the production of bioactive metabolites. A total of 273 isolates were obtained and subjected to antagonistic activity tests against human pathogenic germs. A strain with a broad-spectrum antimicrobial activity was selected and identified as Nocardiopsis dassonvillei GSBS4, with high sequence similarities to N. dassonvillei subsp. dassonvilleiT X97886.1 (99%) based on polyphasic taxonomy approach and 16S ribosomal ribonucleic acid gene sequence analysis. The GSBS4 ethyl acetate crude extract showed strong antibacterial activity towards pathogenic bacteria and Candida albicans. It inhibited biofilm formation by Staphylococcus aureus and methicillin-resistant S. aureus with minimum inhibitory concentrations estimated at 0.144 and 1.15 mg·mL-1 , respectively. A 44% biofilm reduction was obtained for S. aureus and 61% for Pseudomonas aeruginosa. Furthermore, phenols composition of the crude extract showed a significant dose-dependent antioxidant activity by α-diphenyl-β-picrylhydrazyl (57.21%) and 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (64.29%) radicals scavenging assays. Although no inhibition was obtained on human coronavirus human coronavirus (HCoV) 229E and on model enterovirus (poliovirus 1) infection, a dose-dependent increase in cell viability of HCoV 229E-infected cells was noticed as the viability increased from 21% to 37%. Bioassay-guided fractionation of the crude extract gave a fraction showing antibacterial activity, which was analyzed by liquid chromatography-electrospray mass spectrometric technique, providing structural features on a major purple metabolite.

Exploring the potential of Crotalaria juncea flower extracts as a source of antioxidants, antimicrobials, and cytoprotective agents for biomedical applications

Plants provide an unlimited source of bioactive compounds, possessing tremendous applications in the pharmaceutical industry. In the search for sources of antioxidants and antimicrobial agents against human pathogens, ethanol extracts of Crotalaria juncea flowers (CJ flower extract) were evaluated. The highest total phenolic (5.65 μg GAE/ml) and flavonoid (0.43 μg QE/ml) contents were observed in the 100 μg/ml CJ flower extract. To assess antioxidant activity, three in vitro antioxidant tests were employed: DPPH radical-scavenging, ABTS+ radical-scavenging, and hydroxyl radical-scavenging assay. The CJ flower extract demonstrated significant (P < 0.05) antioxidant activity, dependent on the percentage of solvent extraction and the specific assays utilized. The highest antioxidant activity was obtained with 100% ethanol extraction and using the hydroxyl radical-scavenging assay (56.63%). Antimicrobial activity was assessed against six human pathogens, including the fungi Microsporum gypseum and five Gram-positive bacteria (Propionibacterium acnes, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, and Streptococcus mutans), as well as one Gram-negative bacterium (Escherichia coli ). The CJ flower extract inhibited the growth of both fungal and bacterial pathogens. The cytotoxicity of the CJ flower extract was measured using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and the highest concentration of the extract (100 μg/ml) did not affect L929 cell viability. Moreover, the CJ flower extract demonstrated the ability to suppress H2O2-induced toxicity in L929 cells. Overall, the CJ flower extract has potential as an alternative source for exploring new antioxidants, antimicrobial agents, and cytoprotectants that could prove valuable for biomedical applications.

Facile fabrication of Nishamalaki churna mediated silver nanoparticles with antibacterial application

Antimicrobial resistance (AMR) is one of the most serious threats to today's healthcare system. The prime factor behind increasing AMR is the formation of complex bacterial biofilms which acts as the protective shield between the bacterial cell and the antimicrobial drugs. Among various nanoformulations, green synthesized metallic silver nanoparticles are currently gaining research focus in safely breaking bacterial biofilms due to the inherent antimicrobial property of silver. In the current work, the aqueous extract of the ayurvedic formulation Nishamalaki churna is used to exhibit one pot green synthesis of silver nanoparticles. The physicochemical characteristics of Nishamalaki churna extract mediated AgNPs were evaluated using various analytical techniques, like UV-Visible spectrophotometer, FT-IR spectroscopy, SEM, XRD, DLS-Zeta potential analyzer etc. The synthesized spherical AgNPs were well formed within the size range of 30 nm to 80 nm. Furthermore, the synthesized AgNPs showed potent antibacterial effects against two primary AMR-causing bacterial species like Staphylococcus aureus and Pseudomonas aeruginosa with the successful destruction of their biofilm formation. Additionally, these AgNPs have shown profound antioxidant and anti-inflammatory activities as desirable add-on effects required by a prospective antibacterial agent.

Identification of Flavone Derivative Displaying a 4'-Aminophenoxy Moiety as Potential Selective Anticancer Agent in NSCLC Tumor Cells

Five heterocyclic derivatives were synthesized by functionalization of a flavone nucleus with an aminophenoxy moiety. Their cytotoxicity was investigated in vitro in two models of human non-small cell lung cancer (NSCLC) cells (A549 and NCI-H1975) by using MTT assay and the results compared to those obtained in healthy fibroblasts as a non-malignant cell model. One of the aminophenoxy flavone derivatives (APF-1) was found to be effective at low micromolar concentrations in both lung cancer cell lines with a higher selective index (SI). Flow cytometric analyses showed that APF-1 induced apoptosis and cell cycle arrest in the G2/M phase through the up-regulation of p21 expression. Therefore, the aminophenoxy flavone-based compounds may be promising cancer-selective agents and could serve as a base for further research into the design of flavone-based anticancer drugs.

Antimicrobial Activity of an Fmoc-Plantaricin 149 Derivative Peptide against Multidrug-Resistant Bacteria

Antimicrobial resistance poses a major threat to public health. Given the paucity of novel antimicrobials to treat resistant infections, the emergence of multidrug-resistant bacteria renewed interest in antimicrobial peptides as potential therapeutics. This study designed a new analog of the antimicrobial peptide Plantaricin 149 (Pln149-PEP20) based on previous Fmoc-peptides. The minimal inhibitory concentrations of Pln149-PEP20 were determined for 60 bacteria of different species and resistance profiles, ranging from 1 mg/L to 128 mg/L for Gram-positive bacteria and 16 to 512 mg/L for Gram-negative. Furthermore, Pln149-PEP20 demonstrated excellent bactericidal activity within one hour. To determine the propensity to develop resistance to Pln149-PEP20, a directed-evolution in vitro experiment was performed. Whole-genome sequencing of selected mutants with increased MICs and wild-type isolates revealed that most mutations were concentrated in genes associated with membrane metabolism, indicating the most likely target of Pln149-PEP20. Synchrotron radiation circular dichroism showed how this molecule disturbs the membranes, suggesting a carpet mode of interaction. Membrane depolarization and transmission electron microscopy assays supported these two hypotheses, although a secondary intracellular mechanism of action is possible. The molecule studied in this research has the potential to be used as a novel antimicrobial therapy, although further modifications and optimization remain possible.

Biological activities of different plant species belonging to the Asteraceae family

Achillea biebersteinii and Anthemis tinctoria, which are widely distributed species of the Asteraceae family, are used in folk medicine in the form of herbal tea or extract in the treatment of many diseases. The aim of this study was to investigate the chemical content, antimicrobial, antioxidant, enzyme inhibitor activities and cytotoxic effects of 80% ethanol extract of these two species and make a comparative analysis. In accordance with the data obtained, the major component of A. biebersteinii was determined as Cyclododecane (14.47%), while that of A. tinctoria was determined as Phytol (23.15%). A. biebersteinii, which showed moderate activity in terms of antimicrobial activity, produced more active inhibition than A. tinctoria did. Both plants showed high levels of antioxidant activity. The total phenol and total flavonoid contents of A. tinctoria were higher than those of A. biebersteinii. It was determined that there was no significant activity when the extracts were compared with galanthamine, which is the reference drug in terms of enzyme inhibitory activity. When the in vitro anticancer activity of human breast cancer cell line was examined, it was determined that A. tinctoria had a cytotoxic effect at high concentrations (IC50;0.82mg/mL), and A. biebersteinii showed strong cytotoxicity at all concentrations (IC50;&lt;0.0625mg/mL). These two plants of the same family were evaluated in terms of many different biological parameters and it was revealed that A. biebersteinii was more active than A. tinctoria. However, in vivo studies are needed to determine whether these plants can be used as phytotherapeutic agents.

Phytochemical profiling, antimicrobial, and antioxidant activities of hydroethanolic extracts of prickly pear ( Opuntia ficus indica ) fruit and pulp

Phenolic compounds in prickly pear [Opuntia ficus indica (L.) Mill.] are known to contribute to the antioxidant and antimicrobial activities of the prickly pear. The present study aimed to evaluate the antioxidants and in vitro antimicrobial potential in the hydroethanolic extracts of different parts (fruit, cladode, and pulp) of prickly pear. Different polyphenolic compounds were analyzed by using high-performance liquid chromatography. The results indicated that cladode possessed a higher quantity of phenolics compared with that observed in fruit and pulp. The most important phenolic compound in high quantity was gallic acid (66.19 μg/g) in cladode. The 100% aqueous extract of cladode exhibited the highest antioxidant (92%) and antimicrobial activities against Salmonella typhi (3.40 mg/ml), Helicobacter pylori (1.37 mg/ml), Escherichia coli (1.41 mg/ml), and Staphylococcus aureus (1.41 mg/ml). Principal component analysis (PCA) indicated that antioxidant activity and minimum inhibitory concentration (MIC) responses had a significant negative correlation with each other. Overall, the current results provided basic data for choosing prickly pear cladode with high antioxidant capacity for the development and consumption of antioxidant-based alternative medicines and value addition of formulated foods.

Bioactive Azadirachta indica and Melia azedarach leaves extracts with anti-SARS-CoV-2 and antibacterial activities

The leaves of Azadirachta indica L. and Melia azedarach L., belonging to Meliaceae family, have been shown to have medicinal benefits and are extensively employed in traditional folk medicine. Herein, HPLC analysis of the ethyl acetate fraction of the total methanolic extract emphasized the enrichment of both A. indica L., and M. azedarach L. leaves extracts with phenolic and flavonoids composites, respectively. Besides, 4 limonoids and 2 flavonoids were isolated using column chromatography. By assessing the in vitro antiviral activities of both total leaves extracts against Severe Acute Respiratory Syndrome Corona virus 2 (SARS-CoV-2), it was found that A. indica L. and M. azedarach L. have robust anti-SARS-CoV-2 activities at low half-maximal inhibitory concentrations (IC50) of 8.451 and 6.922 μg/mL, respectively. Due to the high safety of A. indica L. and M. azedarach L. extracts with half-maximal cytotoxic concentrations (CC50) of 446.2 and 351.4 μg/ml, respectively, both displayed extraordinary selectivity indices (SI>50). A. indica L. and M. azedarach L. leaves extracts could induce antibacterial activities against both Gram-negative and positive bacterial strains. The minimal inhibitory concentrations of A. indica L. and M. azedarach L. leaves extracts varied from 25 to 100 mg/mL within 30 min contact time towards the tested bacteria. Our findings confirm the broad-spectrum medicinal value of A. indica L. and M. azedarach L. leaves extracts. Finally, additional in vivo investigations are highly recommended to confirm the anti-COVID-19 and antimicrobial activities of both plant extracts.

Antimycobacterial activity and molecular docking of methanolic extracts and compounds of marine fungi from Saldanha and False Bays, South Africa

The number and diversity of drugs in the tuberculosis (TB) drug development process has increased over the years, yet the attrition rate remains very high, signaling the need for continued research in drug discovery. In this study, crude secondary metabolites from marine fungi associated with ascidians collected from Saldanha and False Bays (South Africa) were investigated for antimycobacterial activity. Isolation of fungi was performed by sectioning thin inner-tissues of ascidians and spreading them over potato dextrose agar (PDA). Solid state fermentation of fungal isolates on PDA was then performed for 28 days to allow production of secondary metabolites. Afterwards, PDA cultures were dried and solid-liquid extraction using methanol was performed to extract fungal metabolites. Profiling of metabolites was performed using untargeted liquid chromatography quadrupole time-of-flight tandem mass spectrometry (LC-QTOF-MS/MS). The broth microdilution method was used to determine antimycobacterial activity against Mycobacterium smegmatis mc²155 and Mycobacterium tuberculosis H37Rv, while in silico flexible docking was performed on selected target proteins from M. tuberculosis. A total of 16 ascidians were sampled and 46 fungi were isolated. Only 32 fungal isolates were sequenced, and their sequences submitted to GenBank to obtain accession numbers. Metabolite profiling of 6 selected fungal extracts resulted in the identification of 65 metabolites. The most interesting extract was that of Clonostachys rogersoniana MGK33 which inhibited Mycobacterium smegmatis mc²155 and Mycobacterium tuberculosis H37Rv growth with minimum inhibitory concentrations (MICs) of 0.125 and 0.2 mg/mL, respectively. These results were in accordance with those from in silico molecular docking studies which showed that bionectin F produced by C. rogersoniana MGK33 is a potential inhibitor of M. tuberculosis β-ketoacyl-acyl carrier protein reductase (MabA, PDB ID = 1UZN), with the docking score observed as -11.17 kcal/mol. These findings provided evidence to conclude that metabolites from marine-derived fungi are potential sources of bioactive metabolites with antimycobacterial activity. Even though in silico studies showed that bionectin F is a potent inhibitor of an essential enzyme, MabA, the results should be validated by performing purification of bionectin F from C. rogersoniana MGK33 and in vitro assays against MabA and whole cells (M. tuberculosis).

Antifungal Agents in Wood Protection—A Review

The biodegradation of wood and wood products caused by fungi is recognized as one of the most significant problems worldwide. To extend the service life of wood products, wood is treated with preservatives, often with inorganic compounds or synthetic pesticides that have a negative impact on the environment. Therefore, the development of new, environmentally friendly wood preservatives is being carried out in research centers around the world. The search for natural, plant, or animal derivatives as well as obtaining synthetic compounds that will be safe for humans and do not pollute the environment, while at the same time present biological activity is crucial in terms of environmental protection. The review paper presents information in the literature on the substances and chemical compounds of natural origin (plant and animal derivatives) and synthetic compounds with a low environmental impact, showing antifungal properties, used in research on the ecological protection of wood. The review includes literature reports on the potential application of various antifungal agents including plant extracts, alkaloids, essential oils and their components, propolis extract, chitosan, ionic liquids, silicon compounds, and nanoparticles as well as their combinations.

Health Benefits and Pharmacological Properties of Stigmasterol

Stigmasterol is an unsaturated phytosterol belonging to the class of tetracyclic triterpenes. It is one of the most common plant sterols, found in a variety of natural sources, including vegetable fats or oils from many plants. Currently, stigmasterol has been examined via in vitro and in vivo assays and molecular docking for its various biological activities on different metabolic disorders. The findings indicate potent pharmacological effects such as anticancer, anti-osteoarthritis, anti-inflammatory, anti-diabetic, immunomodulatory, antiparasitic, antifungal, antibacterial, antioxidant, and neuroprotective properties. Indeed, stigmasterol from plants and algae is a promising molecule in the development of drugs for cancer therapy by triggering intracellular signaling pathways in numerous cancers. It acts on the Akt/mTOR and JAK/STAT pathways in ovarian and gastric cancers. In addition, stigmasterol markedly disrupted angiogenesis in human cholangiocarcinoma by tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor receptor-2 (VEGFR-2) signaling down-regulation. The association of stigmasterol and sorafenib promoted caspase-3 activity and down-regulated levels of the anti-apoptotic protein Bcl-2 in breast cancer. Antioxidant activities ensuring lipid peroxidation and DNA damage lowering conferred to stigmasterol chemoprotective activities in skin cancer. Reactive oxygen species (ROS) regulation also contributes to the neuroprotective effects of stigmasterol, as well as dopamine depletion and acetylcholinesterase inhibition. The anti-inflammatory properties of phytosterols involve the production of anti-inflammatory cytokines, the decrease in inflammatory mediator release, and the inhibition of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Stigmasterol exerts anti-diabetic effects by reducing fasting glucose, serum insulin levels, and oral glucose tolerance. Other findings showed the antiparasitic activities of this molecule against certain strains of parasites such as Trypanosoma congolense (in vivo) and on promastigotes and amastigotes of the Leishmania major (in vitro). Some stigmasterol-rich plants were able to inhibit Candida albicans, virusei, and tropicalis at low doses. Accordingly, this review outlines key insights into the pharmacological abilities of stigmasterol and the specific mechanisms of action underlying some of these effects. Additionally, further investigation regarding pharmacodynamics, pharmacokinetics, and toxicology is recommended.

Evaluation of the inhibitory efficacy of quaternary ammonium compounds on in vitro growth of Theileria equi parasite in MASP culture

Equine piroplasmosis has become a global problem of the equine husbandry sector. Haemoprotozoans evolved very quickly and developed resistance against most of the current available drugs. Phospholipid membrane synthesis by choline kinase enzyme is vital for propagation of intra-erythrocytic protozoa parasites. This pathway was targeted in the present study. Quaternary ammonium salts (QAS) and their analogues act against choline and hamper the biosynthesis process for phosphatidylcholine. We analysed anti-T. equi activity of three QAS - decamethonium bromide (DMB), decyl trimethyl ammonium bromide (DTAB) and dodecyl trimethyl ammonium bromide (DDTAB). Theileria equi parasites in vitro treated with different concentrations of DMB, DDTAB and DTAB. Drug treated T. equi failed to multiply further in the viability test. The IC₅₀ value of DMB, DDTAB and DTAB for growth inhibition of T. equi was 14.0 μM, 469.51 nM and 558.40 nM, respectively. DMB, DDTAB and DTAB treated T. equi parasites were observed to be devoid of internal structures, showing pyknotic and degenerative appearances. Various concentration of DMB, DDTAB and DTAB were analysed for their cytotoxicity and haemolytic activity on horse's PBMCs and RBCs. DMB was less than 10% cytotoxic to PBMCs, while DDTAB and DTAB were 40%-50% cytotoxic at 1000 μM concentrations. The respective CC₅₀ values were 7202.96 μM, 1026.26 μM and 1263.95 μM. DMB and DTAB showed least haemolytic activity (<3%); whereas DDTAB was more haemolytic to RBCs at highest concentration of 2000 μM. The respective CC₅₀ values of these drugs were 224495.3 μM, and 39101.35 μM; 713.54 μM. Specific selective index for DMB, DDTAB and DTAB values with respect to host's PBMC and RBC cells, were 514.50, 2185.81, 2263.52 and 16035.38, 1519.75, 70023.91, respectively. These data indicated its non-toxicity to host's cells and selective potential of anti-T. equi in vitro activity.

Effect of herbal compounds on coronavirus; a systematic review and meta-analysis

BACKGROUND

The new coronavirus (COVID-19) has been transmitted exponentially. Numerous studies have been performed in recent years that have shown the inhibitory effect of plant extracts or plant-derived compounds on the coronavirus family. In this study, we want to use systematic review and meta-analysis to answer the question, which herbal compound has been more effective?

MAIN BODY

The present study is based on the guidelines for conducting meta-analyzes. An extensive search was conducted in the electronic database, and based on the inclusion and exclusion criteria, articles were selected and data screening was done. Quality control of articles was performed. Data analysis was carried out in STATA software.

CONCLUSION

Due to the variety of study methods, definitive conclusions are not possible. However, in this study, we attempted to gather all the available evidence on the effect of plant compounds on SARS-COV-2 to be used for the development and use of promising antiviral agents against this virus and other coronaviruses. Trypthantrin, Sambucus extract, S. cusia extract, Boceprevir and Indigole B, dioica agglutinin urtica had a good effect on reducing the virus titer. Also among the compounds that had the greatest effect on virus inhibition, Saikosaponins B2, SaikosaponinsD, SaikosaponinsA and Phillyrin, had an acceptable selectivity index greater than 10. Andrographolide showed the highest selectivity index on SARS-COV-2. Our study confirmed insufficient data to support alkaloid compounds against SARS-COV-2, and the small number of studies that used alkaloid compounds was a limitation. It is recommended to investigate the effect of more alkaloid compounds against Corona virus.

In vitro antibacterial and cytotoxic effects of Euphorbia grandicornis Blanc chemical constituents

BACKGROUND

Euphorbia grandicornis is widely utilized in traditional medicine for the treatment of microbial infections including sexually transmitted diseases such as syphilis, gonorrhoea and for healing of wounds.

OBJECTIVE

The aim of this work was to isolate and evaluate the antibacterial and anticancer activities of Euphorbia grandicornis chemical constituents.

METHODS

Chemical constituents were isolated and identified using various spectroscopic techniques such as IR, MS, and NMR. The single point growth inhibitory potential of the compounds was determined using a 96-well plate based assay.

RESULTS

The CH₂Cl₂ crude extracts exhibited potent antibacterial activity against Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 6538 with percentage growth of 94.90 ± 4.24 and 29.47 ± 4.89 respectively. Hence, the CH₂Cl₂ crude extract was further subjected to column chromatography which resulted in the isolation of methyl 2,5-dihydroxybenzoate (1), n-octyl benzoate (2), friedelanol (3), and germanicol (4) and identification of compounds 12-24 for the first time in the species based on the LC-MS/MS spectroscopic data. The purified compounds (1-4), and previously reported compounds (5-11) were evaluated for antibacterial activities against S. aureus and E. coli, as well as the cytotoxicity effects against HeLa cells. Of the purified compounds, methyl 2,5-dihydroxybenzoate (1), was the most active against E.coli and S. aureus with a percentage growth of 19.12 ± 0.65 and 23.32 ± 0.23 respectively. β-amyrin (6), and β-sitosterol (8), were active against S. aureus with percentage growth of 27.17 ± 0.07, and 47.79 ± 2.99 respectively.

CONCLUSION

The results obtained from this study indicate that E. grandicornis, is a rich source of chemical constituents that may provide new lead compounds for the development of antibacterial agents.

Pyrazole-Based Water-Soluble Dendrimer Nanoparticles as a Potential New Agent against Staphylococci

Although the antimicrobial potency of the pyrazole nucleus is widely reported, the antimicrobial effects of the 2-(4-bromo-3,5-diphenyl-pyrazol-1-yl)-ethanol (BBB4), found to be active against several other conditions, have never been investigated. Considering the worldwide need for new antimicrobial agents, we thought it noteworthy to assess the minimum inhibitory concentration (MICs) of BBB4 but, due to its scarce water-solubility, unequivocal determinations were tricky. To obtain more reliable MICs and to obtain a substance also potentially applicable in vivo, we recently prepared water-soluble, BBB4-loaded dendrimer nanoparticles (BBB4-G4K NPs), which proved to have physicochemical properties suitable for clinical application. Here, with the aim of developing a new antibacterial agent based on BBB4, the BBB4-G4K NPs were tested on several strains of different species of the Staphylococcus genus. Very low MICs (1.5–3.0 µM), 15.5–124.3-fold lower than those of the free BBB4, were observed against several isolates of S. aureus and S. epidermidis, the most pathogenic species of this genus, regardless of their resistance patterns to antibiotics. Aiming at hypothesizing a clinical use of BBB4-G4K NPs for staphylococcal skin infections, cytotoxicity experiments on human keratinocytes were performed; it was found that the nano-manipulated BBB4 released from BBB4-G4K NPs (LD₅₀ 138.6 µM) was 2.5-fold less cytotoxic than the untreated BBB4 (55.9 µM). Due to its physicochemical and biological properties, BBB4-G4K NPs could be considered as a promising novel therapeutic option against the very frequent staphylococcal skin infections.

Efficacy of Ursolic Acid-Enriched Water-Soluble and Not Cytotoxic Nanoparticles against Enterococci

Ursolic acid (UA), a pentacyclic triterpenoid acid found in many medicinal plants and aromas, is known for its antibacterial effects against multi-drug-resistant (MDR) Gram-positive bacteria, which seriously threaten human health. Unfortunately, UA water-insolubility, low bioavailability, and systemic toxicity limit the possibilities of its application in vivo. Consequently, the beneficial activities of UA observed in vitro lose their potential clinical relevance unless water-soluble, not cytotoxic UA formulations are developed. With a nano-technologic approach, we have recently prepared water-soluble UA-loaded dendrimer nanoparticles (UA-G4K NPs) non-cytotoxic on HeLa cells, with promising physicochemical properties for their clinical applications. In this work, with the aim of developing a new antibacterial agent based on UA, UA-G4K has been tested on different strains of the Enterococcus genus, including marine isolates, toward which UA-G4K has shown minimum inhibitory concentrations (MICs) very low (0.5-4.3 µM), regardless of their resistance to antibiotics. Time-kill experiments, in addition to confirming the previously reported bactericidal activity of UA against E. faecium, also established it for UA-G4K. Furthermore, cytotoxicity experiments on human keratinocytes revealed that nanomanipulation of UA significantly reduced the cytotoxicity of UA, providing UA-G4K NPs with very high LD₅₀ (96.4 µM) and selectivity indices, which were in the range 22.4-192.8, depending on the enterococcal strain tested. Due to its physicochemical and biological properties, UA-G4K could be seriously evaluated as a novel oral-administrable therapeutic option for tackling difficult-to-treat enterococcal infections.

Bactericidal Activity of Non-Cytotoxic Cationic Nanoparticles against Clinically and Environmentally Relevant Pseudomonas spp. Isolates

Difficult-to-treat bacterial infections caused by resistant human and plant pathogens severely afflict hospitals, and concern the agri-food sectors. Bacteria from the Pseudomonadaceae family, such as P. aeruginosa, P. putida, P. fluorescens, and P. straminea, can be responsible for severe nosocomial infections in humans. P. fragi is the major cause of dairy and meat spoilage, while P. syringae can infect a wide range of economically important plant species, including tobacco, kiwi, and tomato. Therefore, a cationic water-soluble lysine dendrimer (G5-PDK) was tested on several species of Pseudomonas genus. Interestingly, G5-PDK demonstrated variable minimum inhibitory concentrations (MICs), depending on their pigment production, on Pseudomonas aeruginosa (1.6-> 6.4 µM), MICs = 3.2-6.4 µM on P. putida clinical isolates producing pyoverdine, and very low MICs (0.2-1.6 µM) on strains that produced non-pigmented colonies. Time-kill experiments established the rapid bactericidal activity of G5-PDK. In the cytotoxicity experiments on human keratinocytes, after 4 h of treatment with G5-PDK at concentrations 16-500 × MIC, more than 80% of viable cells were observed, and after 24 h, the selectivity indices were maintained above the maximum value reported as acceptable. Due to its proven bactericidal potency and low cytotoxicity, G5-PDK should be seriously considered to counteract clinically and environmentally relevant Pseudomonas isolates.

The Genus Eriosema (Fabaceae): From the Ethnopharmacology to an Evidence-Based Phytotherapeutic Perspective?

The genus Eriosema (Fabaceae) includes approximately 150 species widely distributed across tropical and subtropical regions of the world (Africa, Neotropics, Asia and Australia). Throughout these regions, several species are used since centuries in different traditional medicinal systems, while others are used as food or food supplement. The present review attempts to critically summarize current information concerning the uses, phytochemistry and pharmacology of the Eriosema genus and to evaluate the therapeutic potential. The information published in English and French (up to September 2020) on ethnopharmacology or traditional uses, chemistry, pharmacology and toxicology of Eriosema genus was collected from electronic databases [SciFinder, PubMed, Google, Google Scholar, Scopus, Web of Science, Prelude Medicinal Plants—http://www.ethnopharmacologia.org/recherche-dans-prelude/?plant, The Plant List (http://www.theplantlist.org/), POWO (http://powo.science.kew.org/) and IUCN Red List Categories (https://www.iucnredlist.org/)], conference proceedings, books, M.Sc. and Ph.D. dissertations. The information retrieved on the ethnomedicinal indications of Eriosema genus allowed to list 25 species (∼16.6% of the genus). The majority of uses is recorded from Africa. Phytochemical analyses of 8 species led to the identification and/or isolation of 107 compounds, with flavonoids (69.2%), chromones (7.5%) and benzoic acid derivatives (3.7%) as the main chemical classes. Pharmacological investigations with crude extracts and isolated compounds showed a broad range of activities including aphrodisiac, estrogenic, anti-osteoporosis, hypolipidemic, anti-diabetic, anti-diarrheal, anti-microbial, anti-oxidant, anthelmintic, anti-cancer, and acetylcholinesterase inhibitory activities. Despite the low number of Eriosema species tested, there is convincing evidence in vitro and in vivo studies validating some traditional and ethnobotanical uses. However, the utility of several of the described uses has not yet been confirmed in pharmacological studies. Reviewed data could serve as a reference tool and preliminary information for advanced research on Eriosema species.

Ethnobotany and the Role of Plant Natural Products in Antibiotic Drug Discovery

The crisis of antibiotic resistance necessitates creative and innovative approaches, from chemical identification and analysis to the assessment of bioactivity. Plant natural products (NPs) represent a promising source of antibacterial lead compounds that could help fill the drug discovery pipeline in response to the growing antibiotic resistance crisis. The major strength of plant NPs lies in their rich and unique chemodiversity, their worldwide distribution and ease of access, their various antibacterial modes of action, and the proven clinical effectiveness of plant extracts from which they are isolated. While many studies have tried to summarize NPs with antibacterial activities, a comprehensive review with rigorous selection criteria has never been performed. In this work, the literature from 2012 to 2019 was systematically reviewed to highlight plant-derived compounds with antibacterial activity by focusing on their growth inhibitory activity. A total of 459 compounds are included in this Review, of which 50.8% are phenolic derivatives, 26.6% are terpenoids, 5.7% are alkaloids, and 17% are classified as other metabolites. A selection of 183 compounds is further discussed regarding their antibacterial activity, biosynthesis, structure-activity relationship, mechanism of action, and potential as antibiotics. Emerging trends in the field of antibacterial drug discovery from plants are also discussed. This Review brings to the forefront key findings on the antibacterial potential of plant NPs for consideration in future antibiotic discovery and development efforts.

Antimicrobial activity of polyphenolic compounds from Spirulina against food-borne bacterial pathogens

Food-borne drug-resistant bacteria have adverse impacts on both food manufacturers and consumers. Disillusionment with the efficacy of current preservatives and antibiotics for controlling food-borne pathogens, especially drug-resistant bacteria, has led to a search for safer alternatives from natural sources. Spirulina have been recognized as a food supplement, natural colorant, and enriched source of bioactive secondary metabolites. The main objectives of this study were to isolate polyphenolic compounds from Spirulina and analyze their antibacterial potential against drug-resistant food-borne bacterial pathogens. We found that fraction B of methanol extract contained a high quantity of polyphenols exhibiting broad spectrum antimicrobial effects against drug-resistant food-borne bacterial pathogens. Potential secondary metabolites, such as benzophenone, dihydro-methyl-phenylacridine, carbanilic acid, dinitrobenzoate, propanediamine, isoquinoline, piperidin, oxazolidin, and pyrrolidine, were identified by gas chromatography and mass spectrophotometry (GCMS). These metabolites are active against both gram-positive and gram-negative pathogens. Our work suggests that phenolic compounds from Spirulina provide a natural and sustainable source of food preservatives for future use.

Antibacterial and cytotoxic prenylated dihydrochalcones from Eriosema montanum

Two new prenylated dihydrochalcones (1,2) and eighteen known secondary metabolites (3-20) were isolated from the CH₂Cl₂-MeOH (1:1) extracts of the roots, the stem bark and the leaves of Eriosema montanum Baker f. (Leguminosae). The structures of the isolated compounds were characterized by NMR, IR, and UV spectroscopic and mass spectrometric analyses. The structures of compounds 5, 10, 11 and 13 were confirmed by single crystal X-ray diffraction. The antibacterial activity of the crude extracts and the isolated constituents were established against Gram-positive and Gram-negative bacteria. Among the tested compounds, 1-4 and 10 showed strong activity against the Gram-positive bacterium Bacillus subtilis with minimum inhibitory concentration (MIC) ranging from 3.1 to 8.9 μM, as did the leaf crude extract with an MIC of 3.0 μg/mL. None of the crude extracts nor the isolated compounds were active against Escherichia coli. Compounds 1, 3 and 4 showed higher cytotoxicity, evaluated against the human breast cancer cell line MCF-7, with EC₅₀ of 7.0, 18.0 and 18.0 μM, respectively. These findings contribute to the phytochemical understanding of the genus Eriosema, and highlight the pharmaceutical potential of prenylated dihydrochalcones.

Inhibitory effect of Newtonia extracts and myricetin-3-o-rhamnoside (myricitrin) on bacterial biofilm formation

BACKGROUND

Diarrhoea is a major health issue in both humans and animals and may be caused by bacterial, viral and fungal infections. Previous studies highlighted excellent activity of Newtonia buchananii and N. hildebrandtii leaf extracts against bacterial and fungal organisms related to diarrhoea-causing pathogens. The aim of this study was to isolate the compound(s) responsible for antimicrobial activity and to investigate efficacy of the extracts and purified compound against bacterial biofilms.

METHODS

The acetone extract of N. buchananii leaf powder was separated by solvent-solvent partitioning into eight fractions, followed by bioassay-guided fractionation for isolation of antimicrobial compounds. Antibacterial activity testing was performed using a broth microdilution assay. The cytotoxicity was evaluated against Vero cells using a colorimetric MTT assay. A crystal violet method was employed to test the inhibitory effect of acetone, methanol: dichloromethane and water (cold and hot) extracts of N. buchananii and N. hildebrandtii leaves and the purified compound on biofilm formation of Pseudomonas aeruginosa, Escherichia coli, Salmonella Typhimurium, Enterococcus faecalis, Staphylococcus aureus and Bacillus cereus.

RESULTS

Myricetin-3-o-rhamnoside (myricitrin) was isolated for the first time from N. buchananii. Myricitrin was active against B. cereus, E. coli and S. aureus (MIC = 62.5 μg/ml in all cases). Additionally, myricitrin had relatively low cytotoxicity with IC₅₀ = 104 μg/ml. Extracts of both plant species had stronger biofilm inhibitory activity against Gram-positive than Gram-negative bacteria. The most sensitive bacterial strains were E. faecalis and S. aureus. The cold and hot water leaf extracts of N. buchananii had antibacterial activity and were relatively non-cytotoxic with selectivity index values of 1.98-11.44.

CONCLUSIONS

The purified compound, myricitrin, contributed to the activity of N. buchananii but it is likely that synergistic effects play a role in the antibacterial and antibiofilm efficacy of the plant extract. The cold and hot water leaf extracts of N. buchananii may be developed as potential antibacterial and antibiofilm agents in the natural treatment of gastrointestinal disorders including diarrhoea in both human and veterinary medicine.

Antimicrobial flavonoids as a potential substitute for overcoming antimicrobial resistance

BACKGROUND

Infectious diseases are the leading cause of death in 21^st century due to antimicrobial resistance and scarcity of new molecules to undertake rising infections. There could be a multiple reasons behind antimicrobial resistance whether it is increased drug metabolism or bacterial endotoxins. The demand of effective medication is increasing day by day to treat microbial infections and combat antimicrobial resistance. In recent years most of the synthetic antimicrobials developed resistance so natural products could provide better options to fulfill this demand. There has been increasing interest in the research on flavonoids because various flavonoids were found to be effective against pathogenic microorganisms.

OBJECTIVE

The objective of this article will be to explore antimicrobial activity of flavonoids with special focus on their possible mechanism of action.

METHODS

The article reviewed recent literature related to flavonoids with antimicrobial activity, which were isolated from various sources and the compounds showing fairly good activity against tested microbial species were discussed.

RESULTS

By throughout literature review it has been found that flavonoids show antimicrobial effect by inhibiting virulence factors, efflux pump, biofilm formation, membrane disruption, cell envelop synthesis, nucleic acid synthesis, and bacterial motility inhibition.

CONCLUSION

Most of the antimicrobial drugs available now a days are ineffective due to development of resistance to them. Flavonoids have the potential to overcome this emerging crisis as this class of natural products showed the antimicrobial activity by different mechanisms than those of conventional drugs, so flavonoid could be an effective treatment of pathogenic infections.

Validation of in-vitro bioassay methods: Application in herbal drug research

This present review described the validation method of in-vitro bioassay for its application in herbal drug research. Seven sequencing steps that can be taken for performing a valid bioassay include: literature survey, sample stability evaluation, Biosystem performance testing, Sample performance evaluation, determination of 50% effective concentration or cytotoxic concentrations, selective index evaluation, and determination of accurate relative potency of sample. Detailed methods and acceptance criteria for each step are described herein. Method calculations of the relative potency of sample using European Pharmacopeia 10.0, 5.3 (2020) were recommended instead of using United States Pharmacopeia 42 (2019). For having reliable data and conclusions, all methods (chemical and bioassay) need to be first validated before any data collection. Absence of any validation method may results in incorrect conclusions and bias.

The Inhibitory Effect of Plant Extracts on Growth of the Foodborne Pathogen, Listeria monocytogenes

Listeria monocytogenes is a foodborne pathogen responsible for about 1600 illnesses each year in the United States (US) and about 2500 confirmed invasive human cases in European Union (EU) countries. Several technologies and antimicrobials are applied to control the presence of L. monocytogenes in food. Among these, the use of natural antimicrobials is preferred by consumers. This is due to their ability to inhibit the growth of foodborne pathogens but not prompt negative safety concerns. Among natural antimicrobials, plant extracts are used to inactivate L. monocytogenes. However, there is a large amount of these types of extracts, and their active compounds remain unexplored. The aim of this study was to evaluate the antibacterial activity against L. monocytogenes of about 800 plant extracts derived from plants native to different countries worldwide. The minimal inhibitory concentrations (MICs) were determined, and scanning electron microscopy (SEM) was used to verify how the plant extracts affected L. monocytogenes at the microscopic level. Results showed that 12 of the plant extracts had inhibitory activity against L. monocytogenes. Future applications of this study could include the use of these plant extracts as new preservatives to reduce the risk of growth of pathogens and contamination in the food industry from L. monocytogenes.

Chemical constituents of the leaves of Anthonotha macrophylla (Leguminosae)

The present study deals with the isolation and the characterization of the chemical constituents from the leaves of Anthonotha macrophylla (Leguminosae). Using various chromatographic techniques (TLC, CC, HPLC), the methanolic extract of the leaves of Anthonotha macrophylla yielded one new alkaloid (1) as well as six known compounds amongst which an alkane (2), isolated for the first time from a natural product, an ester of fatty acid (3), two isocoumarines (4-5), a sterol (6) and a disaccharide (7). Their structures were elucidated using spectroscopic technics including extensive 1-D and 2-D NMR, HR-SM experiments.

Anti-Fungal Efficacy and Mechanisms of Flavonoids

The prevalence of fungal infections is growing at an alarming pace and the pathogenesis is still not clearly understood. Recurrence of these fungal diseases is often due to their evolutionary avoidance of antifungal resistance. The development of suitable novel antimicrobial agents for fungal diseases continues to be a major problem in the current clinical field. Hence, it is urgently necessary to develop surrogate agents that are more effective than conventional available drugs. Among the remarkable innovations from earlier investigations on natural-drugs, flavonoids are a group of plant-derived substances capable of promoting many valuable effects on humans. The identification of flavonoids with possible antifungal effects at small concentrations or in synergistic combinations could help to overcome this problem. A combination of flavonoids with available drugs is an excellent approach to reduce the side effects and toxicity. This review focuses on various naturally occurring flavonoids and their antifungal activities, modes of action, and synergetic use in combination with conventional drugs.

Toxoflavin Produced by Burkholderia gladioli from Lycoris aurea Is a New Broad-Spectrum Fungicide

Fungal infections not only cause extensive agricultural damage but also result in serious diseases in the immunodeficient populations of human beings. Moreover, the increasing emergence of drug resistance has led to a decrease in the efficacy of current antifungals. Thus, screening of new antifungal agents is imperative in the fight against antifungal drug resistance. In this study, we show that an endophytic bacterium, Burkholderia gladioli HDXY-02, isolated from the medicinal plant Lycoris aurea, showed broad-spectrum antifungal activity against plant and human fungal pathogens. An antifungal ability assay indicated that the bioactive component was produced from strain HDXY-02 having an extracellular secreted component with a molecular weight lower than 1,000 Da. In addition, we found that this new antifungal could be produced effectively by liquid fermentation of HDXY-02. Furthermore, the purified component contributing to the antifungal activity was identified to be toxoflavin, a yellow compound possessing a pyrimido[5,4-e][1,2,4]triazine ring. In vitro bioactivity studies demonstrated that purified toxoflavin from B. gladioli HDXY-02 cultures had a significant antifungal activity against the human fungal pathogen Aspergillus fumigatus, resulting in abolished germination of conidia. More importantly, the growth inhibition by toxoflavin was observed in both wild-type and drug-resistant mutants (cyp51A and non-cyp51A) of A. fumigatus Finally, an optimized protocol for the large-scale production of toxoflavin (1,533 mg/liter) has been developed. Taken together, our findings provide a promising biosynthetic resource for producing a new antifungal reagent, toxoflavin, from isolates of the endophytic bacterium B. gladioli IMPORTANCE Human fungal infections are a growing problem associated with increased morbidity and mortality. Moreover, a growing number of antifungal-resistant fungal isolates have been reported over the past decade. Thus, the need for novel antifungal agents is imperative. In this study, we show that an endophytic bacterium, Burkholderia gladioli, isolated from the medicinal plant Lycoris aurea, is able to abundantly secrete a compound, toxoflavin, which has a strong fungicidal activity not only against plant fungal pathogens but also against human fungal pathogens Aspergillus fumigatus and Candida albicans, Cryptococcus neoformans, and the model filamentous fungus Aspergillus nidulans More importantly, toxoflavin also displays an efficacious inhibitory effect against azole antifungal-resistant mutants of A. fumigatus Consequently, our findings provide a promising approach to abundantly produce toxoflavin, which has novel broad-spectrum antifungal activity, especially against those currently problematic drug-resistant isolates.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2013-2014

This review is the eighth update of the original article published in 1999 on the application of Matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2014. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly- saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 37:353-491, 2018.

Recent advances on topical antimicrobials for skin and soft tissue infections and their safety concerns

Antimicrobial resistance of disease-related microorganisms is considered a worldwide prevalent and serious issue which increases the failure of treatment outcomes and leads to high mortality. Considering that the increased resistance to systemic antimicrobial therapy often needs of the use of more toxic agents, topical antimicrobial therapy emerges as an attractive route for the treatment of infectious diseases. The topical antimicrobial therapy is based on the absorption of high drug doses in a readily accessible skin surface, resulting in a reduction of microbial proliferation at infected skin sites. Topical antimicrobials retain the following features: (a) they are able to escape the enzymatic degradation and rapid clearance in the gastrointestinal tract or the first-pass metabolism during oral administration; (b) alleviate the physical discomfort related to intravenous injection; (c) reduce possible adverse effects and drug interactions of systemic administrations; (d) increase patient compliance and convenience; and (e) reduce the treatment costs. Novel antimicrobials for topical application have been widely exploited to control the emergence of drug-resistant microorganisms. This review provides a description of antimicrobial resistance, common microorganisms causing skin and soft tissue infections, topical delivery route of antimicrobials, safety concerns of topical antimicrobials, recent advances, challenges and future prospective in topical antimicrobial development.

Chemical composition and pharmacological activities of Pisum sativum

BACKGROUND

Consumption of vegetables has been proven to be effective in the prevention of different diseases. Traditionally edible aerial part of Pisum sativum L. subsp. sativum (Fabaceae) is used to treat diabetes, heart diseases and as blood purifier. Present study was aimed to explore the traditional use of aerial parts of P. sativum as a source of antidiabetic agent. In addition, antioxidant activity and chemical composition was carried out.

METHODS

Total polyphenol content was spectrophotometrically determined using Folin Chiocalteu's reagent while the flavonoids by aluminum chloride colorimetric assay. Identification of compounds of the extract was made through HPLC and LCMS. Antihyperglycemic activity was assessed by oral glucose tolerance test in mice. Antioxidant activity was determined by DPPH free radical scavenging and reducing power assay.

RESULTS

Total polyphenol and total flavonoids content were found to be 51.23 mg gallic acid equivalent and 30.88 mg quercetin equivalent per gram of dried plant extract respectively. Ellagic acid and p-coumeric acid were detected through HPLC. A total of eight compounds including naringenin, β-sitosterol were indentified through LCMS. In OGTT, extract (200 mg/kg bw) showed a 30.24% decrease (P< 0.05) in blood glucose levels at 30 min compared to the normal control. The extract showed IC50 value of 158.52 μg/mL in DPPH scavenging assay and also showed comparable reducing power.

CONCLUSION

Along with other compounds ellagic acid and β-sitosterol present in the extract may be responsible for its antioxidant as well as antihyperglycemic activities. Altogether these results rationalize the use of this vegetable in traditional medicine.

The antibacterial activity of extracts of nine plant species with good activity against Escherichia coli against five other bacteria and cytotoxicity of extracts

Background

The development of antibiotic resistant bacteria stems from a number of factors, including inappropriate use of antibiotics in human and animal health and their prolonged use as growth promoters at sub-clinical doses in poultry and livestock production. We were interested in investigating plants that could be useful in protecting humans or animals against diarrhoea. We decided to work on extracts of nine plant species with good activity against Escherichia coli based on earlier work in the Phytomedicine Programme. Leaves of nine medicinal plant species with high antibacterial activity against Escherichia coli were extracted with acetone and their minimal inhibitory concentration (MIC) values determined using a microplate serial dilution technique against Gram-positive (Staphylococcus aureus, Enterococcus faecalis and Bacillus cereus) and Gram-negative (Escherichia coli, Salmonella Typhimurium and Pseudomonas aeruginosa) bacteria. Bioautography was used to determine the number of bioactive compounds in each extract. In vitro safety of the extracts was determined using the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide reduction assay on Vero cells.

Results

The extracts were active against all the pathogens with average MICs ranging from 0.02 to 0.52 mg/ml. As expected E. coli was relatively sensitive, while E. faecalis and S. Typhimurium were more resistant to the extracts (average MICs of 0.28 mg/ml and 0.22 mg/ml respectively). Cremaspora triflora and Maesa lanceolata leaf extracts had higher activity than the other extracts against Gram-positive and Gram-negative pathogens with mean MICs of 0.07 mg/ml and 0.09 mg/ml respectively. Extracts of Maesa lanceolata and Hypericum roeperianum had the highest total antibacterial activity (TAA) at 1417 and 963 ml/g respectively. All extracts with the exception of that of Maesa lanceolata, Elaeodendron croceum and Calpurnia aurea had relatively low cytotoxicity with LC₅₀ > 20 μg/ml. Cremaspora triflora had the best selectivity index (SI) against S. aureus and E. coli of 2.87 and 1.15 respectively. Hypericum roeperianum had a SI of 1.10 against B. cereus. Bioautography revealed 1–6 visible antimicrobial compounds that were generally non-polar.

Conclusions

There was a weak positive, but statistically non-significant correlation between the potency of the extracts and their cytotoxicity (R = 0.45, ρ > 0.05). The activity of the extracts on the test bacteria was in some cases not correlated with cytotoxicity, as shown by selectivity indices >1. This means that cellular toxicity was probably not due to compounds with antibacterial activity. Some of the extracts had a good potential for therapeutic use against the bacterial pathogens or for application in treating diarhoea. It does not appear that activity against E. coli is a good predictor of activity against Gram-negative rather than Gram-positive bacteria. Further investigation is in progress on C. triflora and H. roeperianum, both of which had promising activities and potential safety based on cytotoxicity.

Review of flavonoids: A diverse group of natural compounds with anti-Candida albicans activity in vitro

Flavonoids are a subdivision of polyphenols, a versatile class of natural compounds that represent secondary metabolites from higher plants and are abundant in human diet. Various protective effects of flavonoids have been reported, including antimicrobial and antifungal activities. Due to the nature of oral candidiasis and the increased use of antifungal agents, several drug-resistant strains have emerged making it impractical to rely on one standard therapeutic regime. The aim of this review is to summarize the antifungal activity of some examples of the major subclasses of flavonoids in pure extract forms against C. albicans in vitro, as reported in literature over the past 10 years (2004-2015). In addition, this review outlines the potential mechanism of actions of flavonoids studied in vitro, which may contribute to a better understanding of flavonoids as multi-targets agents in the treatment and/or prevention of oral candidiasis in clinical settings.

Rare phenolic structures found in the aerial parts of Eriosema laurentii De Wild

Recent pharmacological and toxicological investigations of Eriosema laurentii (Leguminosae) have underlined the plausibility of the use of this plant in traditional African medicine. A very complex pattern of phenolic compounds was detected in the tested extracts. Based on these preceding results a detailed phytochemical study was performed and resulted in the isolation and identification of eleven compounds. All are reported in this plant for the first time and four of those are previously undescribed secondary metabolites: 3,4',6,8-tetrahydroxyflavanone-7-C-glucoside and 3,4',6,8-tetrahydroxyflavone-7-C-glucoside with an extremely rare substitution pattern as well as 1-[2,4-dihydroxy-3-(2-hydroxy-3-methylbut-3-en-1-yl)phenyl]-3-phenylpropan-1-one and 1-[2,4-dihydroxy-3-(2-hydroxy-3-methylbut-3-en-1-yl)phenyl]-3-(4-methoxyphenyl)-propan-1-one. Their structures were elucidated unambiguously by extensive MS- and NMR-experiments.

A Novel Ellagic Acid Derivative from Desbordesia glaucescens

One novel ellagic acid derivative, desglauside (1), was isolated from the leaves of Desbordesia glaucescens together with three known compounds [3 ’,4′-di-O-methylellagic acid (2), oleanolic acid (3) and β-sitosterol-3-O-β-D-glucopyranoside (4)]. Their structures were elucidated on the basis of NMR spectroscopic and MS analysis, and by comparison with related published data. The crude extract, fractions and isolated compounds showed no activity against four yeast strains [Candida albicans (ATCC 9002), C. parapsilopsis (ATCC22019), C. tropicalis (ATCC750), Cryptococcus neoformans (IP95026) and one isolate of Candida guilliermondii].

CHEMICAL CHARACTERIZATION AND EVALUATION OF ANTIBACTERIAL, ANTIFUNGAL, ANTIMYCOBACTERIAL, AND CYTOTOXIC ACTIVITIES OF Talinum paniculatum

In this study, the bioactivity of Talinum paniculatum was evaluated, a plant widely used in folk medicine. The extract from the T. paniculatum leaves (LE) was obtained by percolation with ethanol-water and then subjecting it to liquid-liquid partitions, yielding hexane (HX), ethyl acetate (EtOAc), butanol (BuOH), and aqueous (Aq) fractions. Screening for antimicrobial activity of the LE and its fractions was evaluated in vitro through broth microdilution method, against thirteen pathogenic and non-pathogenic microorganisms, and the antimycobacterial activity was performed through agar diffusion assay. The cytotoxic concentrations (CC90) for LE, HX, and EtOAc were obtained on BHK-21 cells by using MTT reduction assay. The LE showed activity against Serratia marcescens and Staphylococcus aureus, with Minimum Inhibitory Concentration (MIC) values of 250 and 500 µg/mL, respectively. Furthermore, HX demonstrated outstanding activity against Micrococcus luteus and Candida albicans with a MIC of 31.2 µg/mL in both cases. The MIC for EtOAc also was 31.2 µg/mL against Escherichia coli. Conversely, BuOH and Aq were inactive against all tested microorganisms and LE proved inactive against Mycobacterium tuberculosis and Mycobacterium bovis as well. Campesterol, stigmasterol, and sitosterol were the proposed structures as main compounds present in the EF and HX/EtOAc fractions, evidenced by mass spectrometry. Therefore, LE, HX, and EtOAc from T. paniculatum showed potential as possible sources of antimicrobial compounds, mainly HX, for presenting low toxicity on BHK-21 cells with excellent Selectivity Index (SI = CC90/MIC) of 17.72 against C. albicans.