Antibacterial,antifungal and cytotoxic activities of extracts from fish epidermis and epidermal mucus

Annual discards from the world fisheries are estimated to be approximately 20 million metric tonnes (25%) per year. The main objective of this work is to increase the utilisation of by-products (notably skin) from fish species in order to isolate new biologically active compounds. This study presents the results of a screening program for antifungal, antibacterial and cytotoxic activities in epidermal mucus and epidermis extracts of thirteen fish species that are commonly caught in North Atlantic waters and generate an important amount of fish waste. Antimicrobial assays used five Gram-positive bacteria five Gram-negative bacteria and five fungi. Of the 78 extracts tested, 15 showed antibacterial and/or antifungal activities. None of the aqueous fractions were active. One third of the active extracts were ethanolic fractions and three fourth of extracts were dichloromethane fractions. One third of the active fractions were of epidermal origin and the remaining came from mucus fractions. The high levels of inhibitory activity and no apparent toxicity against mouse fibroblasts of extracts of Pollachius virens (CH(3)CH(2)OH/epidermis), Labrus bergylta (CH(2)Cl(2)/mucus), Platichthys flesus (CH(3)CH(2)OH/mucus), Solea solea (CH(2)Cl(2)/mucus) and Scophtalamus rhombus (CH(2)Cl(2)/mucus) suggest they may have potential as novel active therapeutic agents.     

Antibacterial and antifungal activities of some trimethoprim salts

In this study, the antimicrobial activities of Trimethoprim (1), Trimethoprim + Maleic acid (2), Trimethoprim + Oxalic acid dihydrate (3), and Trimethoprim + trans-1,2-Cyclohexanedicarboxylic acid (4) were investigated for their in vitro growth inhibitory activity against human pathogenic as some bacteria and fungi. Substances were tested using the micro-broth dilution assay. The chemical agents showed the same activity against Escherichia coli, Pseudomonas aeruginosa, and Proteus vulgaris. Inhibitory activities of test chemicals against different Candida strains were determined to be widely moderate.     

Antibacterial and antifungal activities of isatin N-Mannich bases.

The antimicrobial and antifungal activities of 29 congeneric isatin N-Mannich bases were investigated by testing against standard test microorganisms and 21 pathogenic Gram-negative microorganisms. Considerable growth inhibition of Gram-negative bacteria and yeasts and slight inhibition of Gram-positive bacteria resulted when they were treated with the various N-Mannich bases of isatin and 5-nitroisatin, respectively.     

Antibacterial and antifungal activities of complexes of ruthenium (II).

Twenty ruthenium (II) complexes (1-5) were evaluated for their in vitro antibacterial and antifungal activity against Enterococcus faecalis (ATCC 29212), Staphylococcus aureus (ATCC 29213), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Candida albicans and Candida tropicalis. Compounds 1d, 1e, 1h, 1i and 1j showed more pronounced antimicrobial activity against Gram-positive bacteria and fungi as compared to the nitrogen donor ruthenium complexes; hydrophobic substituents were significantly more effective. None of the compounds 1-5 exhibited antimicrobial activity against the Gram-negative strains Escherichia coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 27853) with the concentrations ranging between 12.5 and 800 micrograms/ml.     

Antibacterial,antifungal and cytotoxic activities of salviasperanol isolated from Amorphophallus campanulatus

Salviasperanol, a diterpenoid isolated from Amorphophallus campanulatus (Roxb.) Bl. (Araceae) was studied for in vitro antibacterial, antifungal, and cytotoxic activities. The disc diffusion technique was used to determine in vitro antibacterial and antifungal activities. Cytotoxicity was determined against brine shrimp nauplii. In addition, minimal inhibitory concentration (MIC) was determined using serial dilution technique to determine antibacterial potency. The MIC values against these bacteria ranged from 8 to 64 μg/mL. The compound showed significant antibacterial activity against four Gram-positive bacteria (Bacillus subtilis, Bacillus megaterium, Staphylococcus aureus, Streptococcus β-haemolyticus) and six Gram-negative bacteria (Escherichia coli, Shigella dysenteriae, Shigella sonnei, Shigella flexneri, Pseudomonus aeruginosa, Salmonella typhi). The compound showed weak antifungal activity against a number of fungi. In the cytotoxicity determination, the LC₅₀ of the compound against brine shrimp nauplii was 8.02 μg/mL.     

Antibacterial, antifungal and cytotoxic activities of amblyone isolated from Amorphophallus campanulatus

Objective:

To assess the in vitro antibacterial, antifungal and cytotoxic activities of amblyone, a triterpenoid isolated from Amorphophallus campanulatus (Roxb).

Methods:

Disc diffusion technique was used for in vitro antibacterial and antifungal screening. Cytotoxicity was determined against brine shrimp nauplii. In addition, minimum inhibitory concentration (MIC) was determined using serial dilution technique to determine the antibacterial potency.

Results:

Large zones of inhibition were observed in disc diffusion antibacterial screening against four Gram-positive bacteria (Bacillus subtilis, Bacillus megaterium, Staphylococcus aureus and Streptococcus pyogenes) and six Gram-negative bacteria (Escherichia coli, Shigella dysenteriae, Shigella sonnei, Shigella flexneri, Pseudomonas aeruginosa and Salmonella typhi). The MIC values against these bacteria ranged from 8 to 64 μg/ml. In antifungal screening, the compound showed small zones of inhibition against Aspergillus flavus, Aspergillus niger and Rhizopus aryzae. Candida albicans was resistant against the compound. In the cytotoxicity determination, LC₅₀ of the compound against brine shrimp nauplii was 13.25 μg/ml.

Conclusions:

These results suggest that the compound has good antibacterial activity against the tested bacteria, moderate cytotoxicity against brine shrimp nauplii and insignificant antifungal activity against the tested fungi.     

Antibacterial, antifungal and antitumoral activities of 5-carbamoyloxy and 5-acyloxynaphthalene-1,8-carbolactones

Naphthalene-1,8 carbolactone derivatives have been investigated in order to compare their activities using antitumoral, antibacterial and antifungal tests in vitro. The effect of 5-substitution is the reduction of the toxicity and the suppression of the antibiotic activity. The best results were obtained with the ester series (5-acetoxy and 5-propionyloxy) on both antitumoral and antifungal tests.     

Antibacterial and antifungal properties of resveratrol

Resveratrol is a naturally occurring polyphenolic antioxidant that has received massive attention for its potential health benefits, including anticarcinogenesis, anti-aging and antimicrobial properties. The compound is well tolerated by humans and in recent years has been widely used as a nutraceutical. Its common use makes it interesting to investigate with respect to antimicrobial properties both as a single agent and in combination with conventional antibiotics. Resveratrol displays antimicrobial activity against a surprisingly wide range of bacterial, viral and fungal species. At subinhibitory concentrations, resveratrol can alter bacterial expression of virulence traits leading to reduced toxin production, inhibition of biofilm formation, reduced motility and interference with quorum sensing. In combination with conventional antibiotics, resveratrol enhances the activity of aminoglycosides against Staphylococcus aureus, whereas it antagonises the lethal activity of fluoroquinolones against S. aureus and Escherichia coli. Whilst the antimicrobial properties of the compound have been extensively studied in vitro, little is known about its efficacy in vivo. Nonetheless, following topical application resveratrol has alleviated acne lesions caused by the bacterium Propionibacterium acnes. There are currently no in vivo studies addressing its effect in combination with antibiotics, but recent research suggests that there may be a potential for enhancing the antimicrobial efficacy of certain existing antibiotic classes in combination with resveratrol. Given the difficulties associated with introducing new antimicrobial agents to the market, nutraceuticals such as resveratrol may prove to be interesting candidates when searching for solutions for the growing problem of antimicrobial resistance.     

Antibacterial activities of some selected plant extracts of local herbal medicines in Lahore-Pakistan

The antibacterial activity of methanol and acetone extracts of five plant extracts being utilized for the cure of different ailments in Pakistan was studied.The extracts of Curcuma zedoaria,Ipomea turpethum,Sphaeranthus indicus,Terminalia chebula and Tricholepis glaberrima were tested against seven different bacterial strains by well diffusion method and microdilution methods.The pattern of zone of inhibition varied with the plant extracts,the solvent used for extraction and organisms tested.Plant extracts(20 mg/mL) were used to evaluate antibacterial activities.The zone of inhibition exhibited by methanol extracts varied between 11 mm and 32 mm while those of acetone extracts varied between 9 mm and 25 mm respectively.The minimum inhibitory concentration(MIC) exhibited by methanol extracts ranged between(18.4-51.1) mg/mL.Overall methanolic extracts showed more activity than the acetone extracts against tested organisms except for S.indicus.The plants were also analyzed for their elemental composition using atomic absorption spectrophotometer to explore natural sources of essential elements that can be utilized for medicinal purposes.     

Antibacterial and antifungal properties of essential oils

In recent years there has been an increasing interest in the use of natural substances, and some questions concerning the safety of synthetic compounds have encouraged more detailed studies of plant resources. Essential oils, odorous and volatile products of plant secondary metabolism, have a wide application in folk medicine, food flavouring and preservation as well as in fragrance industries. The antimicrobial properties of essential oils have been known for many centuries. In recent years (1987-2001), a large number of essential oils and their constituents have been investigated for their antimicrobial properties against some bacteria and fungi in more than 500 reports. This paper reviews the classical methods commonly used for the evaluation of essential oils antibacterial and antifungal activities. The agar diffusion method (paper disc and well) and the dilution method (agar and liquid broth) as well as turbidimetric and impedimetric monitoring of microorganism growth in the presence of tested essential oils are described. Factors influencing the in vitro antimicrobial activity of essential oils and the mechanisms of essential oils action on microorganisms are reported. This paper gives an overview on the susceptibility of human and food-borne bacteria and fungi towards different essential oils and their constituents. Essential oils of spices and herbs (thyme, origanum, mint, cinnamon, salvia and clove) were found to possess the strongest antimicrobial properties among many tested.     

Light-mediated antifungal activity of Echinacea extracts

This study demonstrated that plant extracts containing acetylenic isobutylamides and polyacetylenes, previously reported as occurring in Echinacea, have phototoxic antimicrobial activity against fungi, including clinically relevant pathogenic fungi. Results show that hexane extracts of Echinacea variably inhibit growth of yeast strains of Saccharomyces cerevisiae, Candida shehata, C. kefyr, C. albicans, C. steatulytica and C. tropicalis under near UV irradiation (phototoxicity) and to a lower extent without irradiation (conventional antifungal activity). The presence of polyacetylenes and alkylamides in extracts of different organs was confirmed in Echinacea purpurea by HPLC in agreement with previously reported data in the literature, and was related to phototoxic activity. Two representative pure compounds, undeca-2E,4Z-diene-8,10-diynoic acid isobutylamide and dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamide, were isolated from Echinacea purpurea root extracts, and compared in a disk assay (5 micrograms/disk) with the highly conjugated trideca-1-ene-3,5,7,9,10-pentayne (previously isolated in our laboratory and found here in E. purpurea). Significant phototoxicity was demonstrated by pure trideca-1-ene-3,5,7,9,10-pentayne, while only minor phototoxicity was induced by the other two acetylenic compounds. Phototoxic activity of Echinacea spp. is primarily attributed to the ketoalkenes and ketoalkynes abundantly present in the roots.     

Antibacterial, antioxidant and cytotoxic activities of extracts of Conyza canadensis (L.) Cronquist growing in Tunisia

Antibacterial antioxidant and cytotoxic activities of petroleum ether, ethyl acetate and methanol extracts of Conyza Canadensis (L.) Cronquist were investigated. Antibacterial activity was evaluated using the agar diffusion and microwell dilution assays against four strains of bacteria. Antioxidant activity was measured by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and the cytotoxic activity was tested against Hep-2 cells (laryngeal carcinoma cell line) using methylene blue assays. Among tested extracts, the methanolic extract exhibited important antibacterial activity. It also showed good antioxidant activity with 50% inhibition concentration (IC₅₀) of 120 μg/ml. Cytotoxicity of extracts was time depend, increasing with exposure time and concentration. At 72 h of incubation, the ethyl acetate and petroleum ether extracts demonstrated effective cytotoxic activity against Hep-2 cells with IC₅₀ values of 45 and 50 μg/ml, respectively.     

Synthesis and antifungal activities of N-arylideneaminoimidazole derivatives

The synthesis and microbiological activities of 1-arylideneaminoimidazole derivatives are reported. Antimicrobial data show that some of the tested imidazoles exhibited an interesting activity on Candida albicans.     

Antibacterial and antifungal screening of newly synthesized benzimidazole-clubbed chalcone derivatives

Different derivatives of chalcone-possessing benzimidazole as a prime motif were synthesized by the authors by acid catalyzed aldol condensation reaction. The synthesis of the desired compounds was initiated by undertaking two parallel reactions: (i) synthesis of 2-mercaptobenzimidazole and (ii) synthesis of N-(4-acetylphenyl)-2-chloroacetamide from 4-aminoacetophenone. The two intermediates so prepared were condensed to yield 2-(1H-benzo[d]imidazol-2-ylthio)-N-(4-acetylphenyl)acetamide (II) using acetone as solvent and K₂CO₃ as a scavenger. The resultant product was further reacted with differently substituted aldehydes to produce the titled compounds using thionyl chloride (SOCl₂) in catalytic amount. The synthesized compounds were confirmed for their structure by means of various spectrometric techniques like IR, ¹H NMR, ¹³C NMR, Mass spectra, and Elemental analysis. Thus-obtained chalcone derivatives were tested for their antibacterial and antifungal activities and were reported in form of minimum inhibitory concentration values.     

Antibacterial and antifungal effects of essential oils from coniferous trees

Essential oils have potential biological effects, i.e., antibiotic, anticarcinogenic, and sedative effects during stress. In the present study, we investigated the antibacterial and antifungal effects of essential oils extracted from the coniferous species Pinus densiflora, Pinus koraiensis, and Chamaecyparis obtusa, because their biological activities have not been yet elucidated. The essential oils were quantified using gas chromatography and identified in gas chromatography-mass spectrometric analysis. Simultaneously, antibacterial and antifungal assays were performed using the essential oils distilled from the needles of coniferous trees. The major components and the percentage of each essential oil were: 19.33% beta-thujene in P. densiflora; 10.49% alpha-pinene in P. koraiensis; 10.88% bornyl acetate in C. obtusa. The essential oils from P. densiflora and C. obtusa have antibacterial effects, whereas essential oils from P. koraiensis and C. obtusa have antifungal effects. These results indicate that the essential oils from the three coniferous trees, which have mild antimicrobial properties, can inhibit the growth of gram-positive and gram-negative bacteria and fungi.