Antioxidant and antifungal activities in vitro of essential oils and extracts of twelve Algerian species of Thymus against some mycotoxigenic Aspergillus genera

The aim of the study was to determine the phenolic and flavonoid content of essential oils (EOs), chloroform and ethanolic extracts of 12 Algerian Thymus species and evaluate their antioxidant and antifungal activities. EOs (1.73 ± 0.30–15.00 ± 1.24 μg/mg), chloroform extracts (33.8 ± 2.42–160.93 ± 3.88 μg/mg) and ethanol extracts (27.01 ± 3.56 –148.46 ± 4.40 μg/mg) showed considerable phenolic content. Flavonoids values of chloroform extracts ranged between 3.39± 0.17 and 20.27 ± 0.29 μg/ml while ethanolic extracts values ranged between 2.81 ± 0.11 and 26.64 ± 0.18 μg/mg. Results of DPPH showed that EOs, chloroform and ethanolic extracts exhibited strong radical scavenging activity (IC50 = 21.75 ± 6.54–338.22 ± 2.99 μg/ml, 22.91 ± 5.59–90.93 ± 1.36 μg/ml, and 33.51 ± 5.72–103.80 ± 4.54 μg/ml, respectively). Inhibition of β-carotene bleaching was potentially performed by all EOs (66.48 ± 2.41–94.06 ± 2.68 %), chloroform extracts (68.98± 1.58–95.30± 1.99%), and ethanolic extracts (62.15 ± 2.51–92.36± 1.15%). The antifungal activity of EOs and extracts was tested using the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). The EOs (0.1 ± 0.00 mg/ mL – 1.06 ± 0.46 mg/mL), chloroform (0.1 ± 0.00 mg/ mL –1.06 ± 0.46 mg/mL) and ethanol (0.1 ± 0.00 mg /mL–1.6 ± 0.00 mg/mL) showed remarkable antifungal activity against mycotoxigenic Aspergillus genera. The MFC of EOs (1.0 ± 0.34 mg/mL and > 4.8 mg/mL) , chloroform (0.26 ± 0.11 mg/mL and > 1.6 mg/mL) and ethanol (0.2 ± 0.00 mg/mL and > 1.6 mg/mL) were fungicidal in nature higher than MICs. The findings of the study indicated that Thymus spp. EOs and extracts could be used as natural alternatives for food industry.

Novel Antifungal Dimers from the Roots of Taiwania cryptomerioides

Five new dimer compounds, namely Taiwaniacryptodimers A‒E (1–5), were isolated from the methanol extract of the roots of Taiwania cryptomerioides. Their structures were established by mean of spectroscopic analysis and comparison of NMR data with those of known analogues. Their antifungal activities were also evaluated. Our results indicated that metabolites 1, 2, 4, and 5 displayed moderate antifungal activities against Aspergillus niger, Penicillium italicum, Candida albicans, and Saccharomyces cerevisiae.

Characteristics of biological control and mechanisms of Pseudomonas chlororaphis zm-1 against peanut stem rot

Background Peanut stem rot is a serious plant disease that causes great economic losses. At present, there are no effective measures to prevent or control the occurrence of this plant disease. Biological control is one of the most promising plant disease control measures. In this study, Pseudomonas chlororaphis subsp. aurantiaca strain zm-1, a bacterial strain with potential biocontrol properties isolated by our team from the rhizosphere soil of Anemarrhena asphodeloides, was studied to control this plant disease. Methods We prepared extracts of Pseudomonas chloroaphis zm-1 extracellular antibacterial compounds (PECEs), determined their antifungal activities by confrontation assay, and identified their components by UPLC-MS/MS. The gene knockout strains were constructed by homologous recombination, and the biocontrol efficacy of P. chlororaphis zm-1 and its mutant strains were evaluated by pot experiments under greenhouse conditions and plot experiments, respectively. Results P. chlororaphis zm-1 could produce extracellular antifungal substances and inhibit the growth of Sclerotium rolfsii, the main pathogenic fungus causing peanut stem rot. The components of PECEs identified by UPLC-MS/MS showed that three kinds of phenazine compounds, i.e., 1-hydroxyphenazine, phenazine-1-carboxylic acid (PCA), and the core phenazine, were the principal components. In particular, 1-hydroxyphenazine produced by P. chlororaphis zm-1 showed antifungal activities against S. rolfsii, but 2-hydroxyphenazine did not. This is quite different with the previously reported. The extracellular compounds of two mutant strains, ΔphzH and ΔphzE, was analysed and showed that ΔphzE did not produce any phenazine compounds, and ΔphzH no longer produced 1-hydroxyphenazine but could still produce PCA and phenazine. Furthermore, the antagonistic ability of ΔphzH declined, and that of ΔphzE was almost completely abolished. According to the results of pot experiments under greenhouse conditions, the biocontrol efficacy of ΔphzH dramatically declined to 47.21% compared with that of wild-type P. chlororaphis zm-1 (75.63%). Moreover, ΔphzE almost completely lost its ability to inhibit S. rolfsii (its biocontrol efficacy was reduced to 6.19%). The results of the larger plot experiments were also consistent with these results. Conclusions P. chlororaphis zm-1 has the potential to prevent and control peanut stem rot disease. Phenazines produced and secreted by P. chlororaphis zm-1 play a key role in the control of peanut stem rot caused by S. rolfsii. These findings provide a new idea for the effective prevention and treatment of peanut stem rot.

Antibacterial and Antifungal Activities of Rumex Confertus Willd

The leaves and roots of Rumex confertus Willd were tested in vitro for antibacterial and fungal activity in the fractions of gasoline, chloroform, ethyl acetate and butanol. As a result, it was found that the leaves of the Rumex confertus Willd plant, chloroform and ethyl acetate fractions of the root part have antibacterial activity against fungi and gram-positive bacteria. Keywords: Rumex confertus Willd, fractions, extracts, antibacterial, antifungal

Antimicrobial Activity of Polyphenols and Natural Polyphenolic Extracts on Clinical Isolates

Antibiotic resistance is a growing global problem that affects people, animals, the environment, and the economy. Many clinically relevant bacteria have become resistant to antibiotics, and this fact is emerging as one of the major threats to public health. The lack of new antibiotics, which is due to their time-consuming and costly development, exacerbates the problem. Therefore, it is necessary to identify new antimicrobial agents to treat bacterial and fungal infections. Plant extracts, which are valuable sources of bioactive compounds, mainly polyphenols, play an important role as a new strategy to combat pathogenic microorganisms. There is an extensive body of supporting evidence for the potent antibacterial and antifungal activities of polyphenols. Furthermore, some polyphenols show a synergistic effect when combined with antibiotics and antifungals, suggesting a promising alternative for therapeutic strategies against antibiotic resistance. However, only a few articles are found when searching the antibacterial or antifungal activities of polyphenols employing clinical isolates. Hence, this review focuses on the antimicrobial activity of polyphenols and extracts rich in polyphenols on clinical isolates, organized according to the World Health Organization priority pathogens classification.

Effect of Extraction Methods on Polyphenols, Flavonoids, Mineral Elements, and Biological Activities of Essential Oil and Extracts of Mentha pulegium L.

Our study evaluated the in vitro antioxidant properties, antibacterial and antifungal activities, anti-inflammatory properties, and chemical composition of the essential oils (EOs), total phenol, and total flavonoid of wild Mentha pulegium L. This study also determined the mineral (nutritional and toxic) elements in the plant. The EOs were extracted using three techniques—hydro distillation (HD), steam distillation (SD), and microwave-assisted distillation (MAD)—and were analyzed using chromatography coupled with flame ionization (GC-FID) and gas chromatography attached with mass spectrometry detector (GC-MS). The antioxidant effects of the EOs were tested with 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), while the antibacterial and antifungal activities of the EO and methanolic extract were tested using Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. Twenty-six compounds were identified in the essential oil, representing 97.73% of the total oil, with 0.202% yield. The major components were pulegone (74.81%), menthone (13.01%) and piperitone (3.82%). Twenty-one elements, including macro- and micro-elements (Ba, Br, Ca, Cl, Co, Cr, Cs, Eu, Fe, K, Mg, Mn, Mo, Na, Rb, Sb, Sc, Sr, Th, U and Zn), were detected using neutron activation analysis (INAA) and inductively coupled plasma optical emission spectrometry (ICP-OES), with the concentration of mineral element close to the FAO recommendation. The results show that the EOs and extracts from Mentha pulegium L. had significant antimicrobial activities against the microorganisms, including five human pathogenic bacteria, one yeast (Candida albicans), and one phytopathogenic fungi. The in vivo anti-inflammatory activities of the leaf extracts were confirmed. The results indicate that the EOs and extracts from Mentha pulegium L. have promising applications in the pharmaceutical industries, clinical applications, and in medical research.

Biochemical Composition, Antimicrobial and Antifungal Activities Assessment of the Fermented Medicinal Plants Extract Using Lactic Acid Bacteria

To prevent foodborne diseases and extend shelf-life, antimicrobial agents may be used in food to inhibit the growth of undesired microorganisms. The present study was aimed to determine the antimicrobial and antifungal activities of the fermented medicinal plants extract using Lactobacillus acidophilus ATCC 4356. The fermentation kinetic parameters, biochemical composition and the volatile compounds of the fermented plant extract was assessed. The results showed that, the fermented plants beverage exhibited high content in polyphenols, flavonoids, and tannins (152.7 mg AGE/ L; 93.6 mg RE/ L; and 62.1mg CE/ L, respectively) to compare with the extract without fermentation. The GC-MS headspace analyses showed the presence of twenty-four interesting volatile compounds. The richness of the fermented plants extracts of polyphenols content and the bioactive compound such as Eucalyptol, Camphene, α-Phellandrene, α-Terpinene improve their biological activity. In addition, the fermented plants extract exhibited a high antimicrobial potential against resistance pathogenic bacteria and fungi determined by different methods. The maximum inhibition showed in the fermented plants beverage against Escherichia coli 25922/3, Pseudomonas aeruginosa 27853 ATCC, Staphylococcus aureus 29213 ATCC, Enterococcus aerogenes 13048 ATCC, Phytophthora infestans P3 4/91 R+, Phytophthora infestans P4 20/01 R, Phytophthora infestans (GL-1). The obtained results support the hypothesis of using whey as a functional ingredient to improve food preservation. The bioprocesses of fermentation technology enhance antimicrobial and antifungal activities which could be used in different industrial applications.

Novel Structural Hybrids of Pyrrole and Thiazole Moieties: Synthesis and Evaluation of Antibacterial and Antifungal Activities

One of the best ways to design new biocidal agents is synthesizing hybrid molecules by combining two or more bioactive moieties in a single molecular scaffold. So, new series of pyrroles bearing a thiazole moiety were synthesized using 1-methyl-1H-pyrrole-2-carbaldehyde thiosemicarbazones 1a–c. Cyclization of thiosemicarbazone derivatives 1a–c with ethyl chloroacetate, ethyl 2-chloropropanoate, chloroacetone and phenacyl bromide afforded the corresponding thiazolidin-4-ones 2a–c, 5-methylthiazolidin-4-ones 3a–c, 4-methyl-2,3-dihydrothiazoles 4a–c, and 4-phenyl-2,3-dihydrothiazoles 5a–c, respectively. The antimicrobial activity of the new thiazole derivatives was evaluated.

Microwave-Assisted Synthesis of Lactose Acetates with Antimicrobial, Cytotoxic, and Antiviral Properties

The task of this study was to perform the "green" synthesis of lactose octaacetate through microwave irradiation and to establish their biological activities. Lactose ester was prepared after microwave-assisted esterification of lactose with acetic anhydride (yield 85-90 %). Lactose octaacetate was characterized by a high degree of acetylation (DS 3.2-3.7). The lactose esters' structure was elucidated by infrared spectroscopy and nuclear magnetic resonance spectroscopy. Lactose octaacetate showed better antifungal activities than antibacterial activities. It possessed slight to moderate antifungal activities against Aspergillus niger ATCC 1015, Penicillium sp., Rhizopus sp., Fusarium moniliforme ATCC 38932. Lactose acetates demonstrated low cytotoxicity against three cell lines: Madin-Darby bovine kidney (MDBK) cells, human epithelial type 2 (HEp-2), and Madin-Darby canine kidney (MDCK) cells. This is the first report for antiviral activity of lactose acetates against herpes simplex virus type 1 (HSV-1), influenza virus A/Panama/2007/99/H3N2 - (IAV/H3N2), PV-1 and Coxsackievirus B1. It was found that this compound showed activity with SI = 2.4 only against PV-1, but against HSV-1, IAV/H3N2, and Coxsackievirus B1 was inactive. The current study demonstrated the applications of lactose acetates as antimicrobial and antiviral substances in food, pharmaceutical, agricultural and cosmetic preparations.