Berrin Özçelik

Cytotoxicity, antiviral and antimicrobial activities of alkaloids, flavonoids, and phenolic acids

Objective: Some natural products consisting of the alkaloids yohimbine and vincamine (indole-type), scopolamine and atropine (tropane-type), colchicine (tropolone-type), allantoin (imidazolidine-type), trigonelline (pyridine-type) as well as octopamine, synephrine, and capsaicin (exocyclic amine-type); the flavonoid derivatives quercetin, apigenin, genistein, naringin, silymarin, and silibinin; and the phenolic acids namely gallic acid, caffeic acid, chlorogenic acid, and quinic acid, were tested for their in vitro antiviral, antibacterial, and antifungal activities and cytotoxicity. Materials and methods: Antiviral activity of the compounds was tested against DNA virus herpes simplex type 1 and RNA virus parainfluenza (type-3). Cytotoxicity of the compounds was determined using Madin-Darby bovine kidney and Vero cell lines, and their cytopathogenic effects were expressed as maximum non-toxic concentration. Antibacterial activity was assayed against following bacteria and their isolated strains: Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Klebsiella pneumoniae, Acinetobacter baumannii, Staphylococcus aureus, Enterococcus faecalis, and Bacillus subtilis, although they were screened by microdilution method against two fungi: Candida albicans and Candida parapsilosis. Results: Atropine and gallic acid showed potent antiviral effect at the therapeutic range of 0.8–0.05 µg ml−1, whilst all of the compounds exerted robust antibacterial effect. Conclusion: Antiviral and antimicrobial effects of the compounds tested herein may constitute a preliminary step for further relevant studies to identify the mechanism of action.

Antiviral and antimicrobial assessment of some selected flavonoids

Abstract In the current study, the results of antibacterial, antifungal, and antiviral activity tests of four flavonoid derivatives, scandenone (1), tiliroside (2), quercetin-3,7-O-α-ʟ-dirhamnoside (3), and kaempferol-3,7-O-α-ʟ-dirhamnoside (4), are presented. Antibacterial and antifungal activities of these compounds were tested against Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Klebsiella pneumoniae, Acinetobacter baumannii, Staphylococcus aureus, Bacillus subtilis, and Enterococcus faecalis, as well as the fungus Candida albicans by a microdilution method. On the other hand, both DNA virus Herpes simplex (HSV) and RNA virus Parainfluenza-3 (PI-3) were employed for antiviral assessment of the compounds using Madin- Darby bovine kidney and Vero cell lines. According to our data, all of the compounds tested were found to be quite active against S. aureus and E. faecalis with MIC values of 0.5 μg/ml, followed by E. coli (2 μg/ml), K. pneumoniae (4 μg/ml), A. baumannii (8 μg/ml), and B. subtilis (8 μg/ml), while they inhibited C. albicans at 1 μg/ml as potent as ketoconazole. However, only compound 3 displayed an antiviral effect towards PI-3 in the range of 8- 32 μg/ml of inhibitory concentration for cytopathogenic effect (CPE).

A study of cytotoxicity of novel chlorokojic acid derivatives with their antimicrobial and antiviral activities.

A series of 6-chloromethyl-3-hydroxy-2-substituted 4H-pyran-4-one derivatives were synthesized and tested for their antimicrobial and antiviral activities. Mannich base derivatives were prepared through the reaction of substituted piperazine or piperidine derivatives on chlorokojic acid and formaline. The structures of the synthesized compounds were confirmed by IR, (1)H and (13)C NMR, ESI-MS, and elemental analysis. According to the activity studies, compounds 2-7 (MIC: 1-2 microg/mL) were found to be highly active against Bacillus subtilis and Staphylococcus aureus, while compounds 3, 5 and 6 showed significant activity against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii. Also, compounds 2-7 were more remarkably active against Candida albicans and Candida parapsilosis (MIC: 4-8 microg/mL). Additionally, compound 2 was the most active one against RNA virus PI-3.

Antiviral and Antimicrobial Profiles of Selected Isoquinoline Alkaloids from Fumaria and Corydalis Species

In the current study, 33 isoquinoline alkaloids belonging to protopine-, benzylisoquinoline-, benzophenanthridine-, spirobenzylisoquinoline-, phthalideisoquinoline-, aporphine-, protoberberine-, cularine-, and isoquinolone-types as well as 7 derivatives of them obtained from some Fumaria and Corydalis species growing in Turkey have been evaluated for their in vitro antiviral and antimicrobial activities. Both DNA virus Herpes simplex (HSV) and RNA virus Parainfluenza (PI-3) were employed for antiviral assessment of the compounds using Madine- Darby bovine kidney and Vero cell lines and their maximum non-toxic concentrations (MNTC) and cytopathogenic effects (CPE) were determined using acyclovir and oseltamivir as the references. Antibacterial and antifungal activities of the alkaloids were tested against Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Klebsiella pneumoniae, Acinetobacter baumannii, Staphylococcus aureus, Bacillus subtilis, and Candida albicans by the microdilution method and compared to ampicilline, ofloxacine, and ketocanazole as the references. The alkaloids did not present any notable antibacterial effect, while they had significant antifungal activity at 8 μg/ml concentration. On the other hand, the alkaloids were found to have selective inhibition against the PI-3 virus ranging between 0.5 and 64 μg/ml as minimum and maximum CPE inhibitory concentrations, whereas they were completely inactive towards HSV.

Inhibitory effects of various essential oils and individual components against extended-spectrum beta-lactamase (ESBL) produced by Klebsiella pneumoniae and their chemical compositions.

In the current study, in vitro inhibitory activity of several essential oils obtained from the cultivated plants, Foeniculum vulgare, Mentha piperita and M. spicata, Ocimum basilicum, Origanum majorana, O. onites, O. vulgare, Satureja cuneifolia, and a number of individual essential oil components of terpene and aromatic types were screened against 10 isolated strains of Klebsiella pneumoniae producing extended-spectrum beta-lactamase (ESBL) enzyme, which makes this microorganism quite resistant against the antibiotics: trimetoprime-sulfametoksazol, sulbactam-ampicilin, clavulonate-amoxicilin, ceftriaxon, cefepime, imipenem, ceftazidime, tobramicine, gentamisine, ofloxacin, and ciprofloksasin. All of the essential oils and the components exerted a remarkable inhibition ranging between 32 and 64 μg/mL against all of these strains as strong as the references (ampicilin and oflaxocin) inhibiting at 32 μg/mL. Besides, chemical compositions of the essential oils were elucidated by gas chromatography-mass spectrometry (GC-MS). The essential oils and the pure components widely found in essential oils screened herein have shown remarkable inhibition against ESBL-producing K. pneumoniae strains, which leads to the suggestion that they may be used as food preservatives for this purpose. Practical Application:  The essential oils obtained from Foeniculum vulgare, Mentha piperita and M. spicata, O.cimum basilicum, Origanum majorana, O. onites, O. vulgare, and Satureja cuneifolia as well as common essential oil components have shown notable inhibitory effects against 10 isolated strains of Klebsiella pneumoniae producing extended-spectrum beta-lactamase (ESBL) enzyme and they might be used as food preservative or ingredient.

Synthesis and antimicrobial activity of 1,4-diaryl-2-azetidinones.

Cycloaddition of substituted 4,4-benzylidene-anilines to in situ prepared dichloroketenes in the presence of dichloroacetyl chloride and triethylamine affords a variety of 2-azetidinones. All the compounds were characterized by IR and 1H NMR. Their antimicrobial activity, against Gram(+) and Gram(-) bacteria and fungi, was tested.

Antibacterial effect of silver-zeolite containing root-canal filling material.

The aim of this study was to determine the in vitro antibacterial effect of two experimental glass ionomer cements (GICs) on Streptococcus milleri, Staphylococcus aureus, and Enterococcus faecalis after 24 and 48 h incubation by using the agar diffusion inhibitory test. Silver zeolite (SZ) was added at 0.2 and 2% mass fraction concentration to GIC (Endion). The control group was Endion with no SZ. Each of them were prepared to uniform size using a custom-made Teflon mold, and the GIC materials were prepared to form disks (n = 5 per group). The effect of these materials on the growth of three bacteria associated with endodontic infections was determined using the agar diffusion inhibitory test. The amounts of silver ion release from these materials were measured with atomic absorption spectrophotometry at 10 min, 24- and 48-h periods. The pH of samples was measured with a pH-meter at 10 min, 24- and 48-h periods. After the incubation period, the agar plates were evaluated and the degrees of bacterial inhibition were measured in millimeters. A comparison of the mean of the test materials was statistically different in each group of specimens (p < 0.05). Between the two tested materials 2% SZ containing GIC showed the largest zone of inhibition on the agar plates of all the tested strains (p < 0.05). The most inhibition in bacterial growth occurred in E. faecalis. Adding 2% SZ to GIC resulted in a significant increase in the silver release into deionized water. This study demonstrated that GIC had an inhibitory affect on Streptococcus milleri, Staphylococcus aureus, and Enterococcus faecalis and that adding SZ increases that affect proportional to its concentration.

Antimicrobial Activities of Plants from the Apicaceae

The aim of this study was to examine the antimicrobial activities of ethanol extracts of five plants containing furanocoumarins. Antimicrobial activities of ethanol extracts of Astrodaucus orientalis (L.) Drude, Bifora radians Bieb., Conium maculatum L., Crithmum maritimum L., Daucus carota L., and standard furanocoumarins (umbelliferone, xanthotoxin, and bergapten) were tested against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, and Candida albicans using a microdilution method. The minimum inhibition dilution (MID) values of the extracts were determined. Astrodaucus orientalis showed the highest antibacterial activity.

Assessment of antimicrobial, insecticidal and genotoxic effects of Melia azedarach L. (chinaberry) naturalized in Anatolia.

In this study, antibacterial, antifungal, insecticidal and genotoxic activities of the fruit and leaf extracts of Melia azedarach of Turkish origin were evaluated for the first time. The antimicrobial activity was assessed against Gram (+) and ( − ) bacteria, four Candida species and three dermatophytic fungus (Trichophyton rubrum, Epidermophyton floccosum and Microsporum gypseum). The insecticidal activity of the methanolic fruit extract was performed against the larvae of Aedes aegpyti, Culex pipiens and Culex quinquefasciatus. The genotoxicity of this extract was evaluated against Drosophila melanogaster by somatic mutation and recombination test. The extracts showed higher antibacterial effect against Gram ( − ) strains (16–32 μg ml− 1 of minimal inhibition concentration, MIC), while the leaf extracts were more effective on Candida albicans (32 μg ml− 1 of MIC). The extracts did not exhibit insecticidal activity and genotoxicity. Total phenol and flavonoid contents of the extracts were determined spectrophotometrically, and the ethyl acetate extract of the leaves was the richest in total flavonoids.

Antimicrobial effect of the extracts from Hypericum perforatum against oral bacteria and biofilm formation

Abstract Context: One traditional medicines, Hypericum perforatum L. (Hypericaceae), possesses several beneficial effects against depression, ulcers, dyspepsia, abdominal pains, burns, bacterial infections, migraine headaches, and sciatica. Objective: The present study investigates the antimicrobial activity of the ethanol extract (HP-EtOH) of H. perforatum and its sub-extracts, namely n-hexane (HP-hexane), chloroform (HP-CHCl3), ethyl acetate (HP-EtOAc), n-butanol (HP-n-BuOH), and water (HP-H2O) extracts, against Streptococcus mutans, S. sobrinus, Lactobacillus plantarum, and Enterococcus faecalis. Materials and methods: For the evaluation of the antimicrobial activity, flowering aerial parts of H. perforatum were extracted with EtOH and then this extract was fractionated to obtain five sub-extracts in different polarities. Antimicrobial activities of HP-EtOH and its sub-extracts against Streptococcus mutans, S. sobrinus, L. plantarum, and E. faecalis were assessed by using colorimetric micro-well dilution at concentration ranges of 64–0.5 μg/ml as well as resazurin microplate and modified microtiter-plate assays between the ranges of 100 and 0.78125 μg/ml. Results: According to the results of the present study, HP-H2O sub-extract displayed strong antibacterial activity (MIC values 8 μg/mL) against S. sobrinus and L. plantarum, and exerted moderate activity against S. mutans and E. faecalis at 32 and 16 μg/mL concentrations, respectively. Other sub-extracts also demonstrated antimicrobial activity against S. sobrinus at a concentration of 16 μg/mL. HP-EtOAc and HP-n-BuOH showed antimicrobial activity against L. plantarum and HP-EtOAc and HP-H2O were also active against E. faecalis at the same concentrations (16 μg/mL). Conclusion: According to the results, we suggest that H. perforatum could be employed as a natural antibacterial agent in oral care products.