Source Of Natural Antimicrobial Compounds Research Articles

Identification of a New Compound (4-Fluoro-2-Trifluoromethyl Imidazole) Extracted from a New Halophilic Bacillus aquimaris Strain Persiangulf TA2 Isolated from the Northern Persian Gulf with Broad-Spectrum Antimicrobial Effect.

The unique ecosystem of the Persian Gulf has made it a rich source of natural antimicrobial compounds produced by various microorganisms, especially bacteria, which can be used in the treatment of infectious diseases, especially those of drug-resistant microbes. This study aimed to identify antimicrobial compounds in the bacteria isolated from the northern region of the Persian Gulf in Abadan (Chavibdeh port), Iran, for the first time. Sampling was performed in the fall on November 15, 2019, from 10 different stations (water and sediment samples). The secondary metabolites of all isolates were extracted, and their antimicrobial effects were investigated. 16S ribosomal ribonucleic acid sequencing was used for the identification of the strains that showed the best inhibition against selected pathogens, and growth conditions were optimized for them. A fermentation medium in a volume of 5000 mL was prepared to produce the antimicrobial compound by the superior strain. The extracted antimicrobial compounds were identified using the gas chromatography-mass spectrometry technique. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for the superior strain. The effects of salinity, pH, and temperature on the production of antimicrobial compounds were determined by measuring the inhibitory region (mm) of methicillin-resistant Staphylococcus aureus (MRSA). Four new strains with antimicrobial properties (i.e., Halomonas sp. strain Persiangulf TA1, Bacillus aquimaris strain Persiangulf TA2, Salinicoccus roseus strain Persiangulf TA4, and Exiguobacterium profundum strain Persiangulf TA9) were identified. The optimum growth temperatures were determined at 37-30, 37, and 40 °C for TA1 and TA2, TA4, and TA9 strains, respectively. The optimum pH values for the four strains were 7, 6-7, 7.5, and 6.5-7.5, respectively. The optimal salt concentrations for the four strains were 15%, 2.5-5%, 7.5%, and 5%, respectively. The ethyl acetate extract of strain Persiangulf TA2 showed extensive antimicrobial activity against human pathogens (75%) and MRSA. The most abundant compound identified in TA2 extract was the new compound 4-fluoro-2-trifluoromethyl imidazole. The MBC and MIC for the ethyl acetate extract of strain TA2 were 20 and 5 mg. mL-1 (Staphylococcus aureus), 40 and 20 mg. mL-1 (MRSA, Escherichia coli, and Enterococcus faecalis), 40 and 10 mg. mL-1 Acinetobacter baumannii), and 80 and 40 mg. mL-1 (Staphylococcus epidermidis, Shigella sp., Bacillus cereus, and Klebsiella pneumoniae), respectively. The optimal conditions for antibiotic production by TA2 strain were 5% salt concentration, pH of 7, and temperature of 35 °C. Newly detected natural compounds in TA2 strain due to superior antimicrobial activity even against MRSA strain can be clinically valuable in pharmacy and treatment.

Antimicrobial Activity against Foodborne Pathogens and Antioxidant Activity of Plant Leaves Traditionally Used as Food Packaging.

In accordance with Thai wisdom, indigenous plant leaves have been used as food packaging to preserve freshness. Many studies have demonstrated that both antioxidant and antimicrobial activities contribute to protecting food from spoilage. Hence, the ethanolic extracts of leaves from selected plants traditionally used as food packaging, including Nelumbo nucifera (1), Cocos nucifera (2), Nypa fruticans (3), Nepenthes mirabilis (4), Dendrocalamus asper (5), Cephalostachyum pergracile (6), Musa balbisiana (7), and Piper sarmentosum (8), were investigated to determine whether they have antioxidant and antimicrobial activities against spoilage microorganisms and foodborne pathogens that might be beneficial for food quality. Extracts 1-4 exhibited high phenolic content at 82.18-115.15 mg GAE/g and high antioxidant capacity on DPPH, FRAP and SRSA assay at 14.71-34.28 μg/mL, 342.92-551.38 μmol Fe2+/g, and 11.19-38.97 μg/mL, respectively, while leaf extracts 5-8 showed lower phenolic content at 34.43-50.08 mg GAE/g and lower antioxidant capacity on DPPH, FRAP, and SRSA at 46.70-142.16 μg/mL, 54.57-191.78 μmol Fe2+/g, and 69.05->120 μg/mL, respectively. Extracts 1-4 possessed antimicrobial activities against food-relevant bacteria, including Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, and Escherichia coli. Only N. mirabilis extract (4) showed antimicrobial activities against Salmonella enterica subsp. enterica serovar Abony and Candida albicans. Extracts 5-8 showed slight antimicrobial activities against B. cereus and E. coli. As the growth and activity of microorganisms are the main cause of food spoilage, N. fruticans (3) was selected for bioassay-guided isolation to obtain 3-O-caffeoyl shikimic acid (I), isoorientin (II) and isovitexin (III), which are responsible for its antimicrobial activity against foodborne pathogens. N. fruticans was identified as a new source of natural antimicrobial compounds I-III, among which 3-O-caffeoyl shikimic acid was proven to show antimicrobial activity for the first time. These findings support the use of leaves for wrapping food and protecting food against oxidation and foodborne pathogens through their antioxidant and antimicrobial activities, respectively. Thus, leaves could be used as a natural packaging material and natural preservative.

Antibacterial potential of leaf and fruit of citrus extract (Citrus aurantifolia) against klebsiella oxytoca

Antimicrobial agents play a crucial role in decreasing the impact of infectious diseases worldwide. Many medicinal plants have been identified as rich sources of natural antimicrobial compounds that can be used as an alternative to traditional treatments for bacterial infections. Indonesia, particularly in the Aceh region, has a warm and humid climate that supports a diverse range of plants that have medicinal properties. One example is the lime (Citrus aurantifolia) which can be used for medicinal purposes.This study aimed to determine the inhibitory effects of leaves and fruit extracts of lime on the growth of Klebsiella oxytoca.The method used was an experimental method with a post-test only control group design. The results showed that both types of extracts contain flavonoid, alkaloid, and saponin compounds. However, triterpenoids were only found in the fruit extract, and steroids were only found in the leaf extract. The antimicrobial test of lime fruit and leaf extracts against Klebsiellaoxytoca bacteria showed that both types of extracts were able to inhibit the growth of the test bacteria at all concentrations.

Antimicrobial, Antibiofilm, and Antioxidant Properties of Boletus edulis and Neoboletus luridiformis Against Multidrug-Resistant ESKAPE Pathogens.

Multidrug-resistant ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) has become the most recurrent global cause of skin and soft-tissue infections, belonging to the WHO priority pathogens list. Successful therapy remains challenging and entails the assessment of novel and successful antibiotics. In this study, mushrooms are considered a valuable and unique source of natural antimicrobial compounds. Therefore, this study aimed to evaluate the antimicrobial and antibiofilm properties of Boletus edulis (B. edulis) and Neoboletus luridiformis (N. luridiformis) aqueous and methanolic extracts against ESKAPE isolates from clinical wound infections. Disk diffusion and microdilution methods were used to assess the antimicrobial activity. Phytochemical characterization was achieved by analysis of total phenols, orthodiphenols content, and antioxidant activity as well as by high-performance liquid chromatography-diode array detector (HPLC-DAD). Human foreskin fibroblasts-1 (HFF-1) cell viability was performed by the MTT assay. Aqueous and methanolic extracts of B. edulis and N. luridiformis showed antimicrobial and antibiofilm properties against multidrug-resistant bacteria, although with different efficacy rates. The results showed that there is a convincing relation between the content of phenolic compounds, antioxidant activity, and antimicrobial activity suggesting that the presence of phenolic compounds may explain the biological effects. HPLC analysis revealed high levels of protocatechuic acid, homogentisic acid, pyrogallol, gallic acid, p-catechin, and dihydroxybenzoic acid in the aqueous extract of B. edulis, explaining the highest antimicrobial and antibiofilm properties. Importantly, the mushrooms extracts were non-cytotoxic at all the tested concentrations. Overall, the tested mushrooms extracts are good candidates to further explore its use in the prevention of wound infection, particularly by multidrug-resistant pathogens.

Antimicrobial Activity of Clerodendrum paniculatum L. n-Hexane and Water Fraction Against Pseudomonas aerugonisa and MRSA

There are many medicinal plants that have been recognized as sources of natural antimicrobial compounds that are used as potentially effective alternatives in the treatment of bacteria. Clerodendrum has been investigated for its antimicrobial activity in some bacteria. The aim of this study is to determine antimicrobial activity of n-hexane and water fraction of pagoda (Clerodendrum paniculatum) leaves against Pseudomonas aeruginosa and Metichilin Resistant Staphylococcus Aureus (MRSA). The antimicrobial activity of the isolated compound was performed by disc diffusion method. N-hexane fraction of Clerodendrum paniculatum have antimicrobial activity to Pseudomonas aeruginosa with inhibition 9.43±0.057; 8.76±0.057; 8.17±0.115; 7.03±0.057 and to MRSA 6.07±0.057; 6.03±0.057; 6.03±0.115; 6.03±0.057 in concentration 300 ppm, 200 ppm, 100 ppm and 50 ppm. Water fraction of Clerodendrum paniculatum have antimicrobial activity to Pseudomonas aeruginosa with inhibition 9.13±0.057; 8.30±0.100; 7.86±0.057; 6.53±0.057 and to MRSA 8.50±0.100; 7.73±0.057; 6.87±0.057; 6.4 ±0.057 in concentration 300 ppm, 200 ppm, 100 ppm and 50 ppm. Based on these results, it was concluded that the n-hexane and water fraction of pagoda (Clerodendrum paniculatum) is potent as an antimicrobial of Pseudomonas aeruginosa.Keywords: Antimicrobial, Clerodendrum paniculatum, fraction, n-hexane, water

Isolation and Characterization of Fish-Gut Bacillus spp. as Source of Natural Antimicrobial Compounds to Fight Aquaculture Bacterial Diseases.

Aquaculture is responsible for more than 50% of global seafood consumption. Bacterial diseases are a major constraint to this sector and associated with misuse of antibiotics, pose serious threats to public health. Fish-symbionts, co-inhabitants of fish pathogens, might be a promising source of natural antimicrobial compounds (NACs) alternative to antibiotics, limiting bacterial diseases occurrence in aquafarms. In particular, sporeforming Bacillus spp. are known for their probiotic potential and production of NACs antagonistic of bacterial pathogens and are abundant in aquaculture fish guts. Harnessing the fish-gut microbial community potential, 172 sporeforming strains producing NACs were isolated from economically important aquaculture fish species, namely European seabass, gilthead seabream, and white seabream. We demonstrated that they possess anti-growth, anti-biofilm, or anti-quorum-sensing activities, to control bacterial infections and 52% of these isolates effectively antagonized important fish pathogens, including Aeromonas hydrophila, A. salmonicida, A. bivalvium, A. veronii, Vibrio anguillarum, V. harveyi, V. parahaemolyticus, V. vulnificus, Photobacterium damselae, Tenacibaculum maritimum, Edwardsiela tarda, and Shigella sonnei. By in vitro quantification of sporeformers' capacity to suppress growth and biofilm formation of fish pathogens, and by assessing their potential to interfere with pathogens communication, we identified three promising candidates to become probiotics or source of bioactive molecules to be used in aquaculture against bacterial aquaculture diseases.

Bacillus spp. as source of Natural Antimicrobial Compounds to control aquaculture bacterial fish pathogens

Bacillus spp. as source of Natural Antimicrobial Compounds to control aquaculture bacterial fish pathogens

Antimicrobial activities, toxicity and phenolic composition of Asphodeline anatolica E. Tuzlaci leaf extracts from Turkey

The antimicrobial activity of acetone, methanol and aqueous extracts of Asphodeline anatolica E. Tuzlaci leaves was evaluated against American type culture collection, food and clinical isolates (Listeria monocytogenes and Staphylococcus aureus including methicillin-resistant strains-MRSA). Biofilm formation, toxicity and characterisation of the polyphenolic content were analysed. The acetone extract demonstrated a higher antibacterial activity against S. aureus including MRSA strains, L. monocytogenes and Pseudomonas aeruginosa than against other extracts. No effect was observed in biofilm formation. The extracts resulted non-toxic against Artemia salina Leach. The phytochemical screening of extracts indicated that they mainly contained six polyphenols identified as catechin 3-O-gallate, protocatechuic acid, diosmin, rutin, cirsimaritin and kaempferol glucoside. This study is the first report on antimicrobial activity and phenolic content of A. anatolica and contributes to enrich the literature data on the biological properties of this plant. A. anatolica leaves have a potential as source of natural antimicrobial compounds.

Characterisation of antimicrobial extracts from dandelion root (Taraxacum officinale) using LC-SPE-NMR.

Plant extracts have traditionally been used as sources of natural antimicrobial compounds, although in many cases, the compounds responsible for their antimicrobial efficacy have not been identified. In this study, crude and dialysed extracts from dandelion root (Taraxacum officinale) were evaluated for their antimicrobial properties against Gram positive and Gram negative bacterial strains. The methanol hydrophobic crude extract (DRE3) demonstrated the strongest inhibition of microbial growth against Staphylococcus aureus, methicillin-resistant S. aureus and Bacillus cereus strains. Normal phase (NP) fractionation of DRE3 resulted in two fractions (NPF4 and NPF5) with enhanced antimicrobial activity. Further NP fractionation of NPF4 resulted in two fractions (NPF403 and NPF406) with increased antimicrobial activity. Further isolation and characterisation of compounds in NPF406 using liquid chromatography solid phase extraction nuclear magnetic resonance LC-SPE-NMR resulted in the identification of 9-hydroxyoctadecatrienoic acid and 9-hydroxyoctadecadienoic acid, while the phenolic compounds vanillin, coniferaldehyde and p-methoxyphenylglyoxylic acid were also identified respectively. The molecular mass of these compounds was confirmed by LC mass spectroscopy (MS)/MS. In summary, the antimicrobial efficacy of dandelion root extracts demonstrated in this study support the use of dandelion root as a source of natural antimicrobial compounds.

Phytochemical Studies and Antimicrobial Screening of Non/Less-Polar Fraction of Psoralea corylifolia by Using GC-MS

Psoralea corylifolia is a well-known medicinal plant, traditionally used against several diseased conditions. The present study was conducted to investigate the phytochemical composition and antimicrobial activity of P. corylifolia seeds. Non/less-polar fraction of methanolic seed extract was subjected to gas chromatography-mass spectrometry (GC-MS) for phytochemical analysis. A total of fourteen compounds were identified which include aromatic, sesquiterpenes, furocoumarins, sterols, fatty acid and their methyl esters. The predominant compounds were epoxycaryophyllene (3), isopsoralen (6), psoralen (7) and bakuchiol (9). Identification of these compounds was also strongly supported by Kovat’s Retention Indices. Furthermore, the n-hexane soluble fraction showed significant antimicrobial activity against several bacterial strains. P. corylifolia seeds represented a unique chemical composition with considerable antimicrobial activity which not only validates their traditional medicinal uses but also indicates their potential as a source of natural antimicrobial compounds.

Antibacterial activity and cytotoxicity of stem bark of two common plants of Bangladesh

Aim: The emergence and spread of antimicrobial resistance is a growing problem in both developing and developed countries and threatens to become a global crisis. In recent years, attempts have been made to investigate indigenous medicines used against infectious diseases, to help in developing safer antimicrobial and anticancer drugs. As part of the further advancement of this research arena, an attempt has been made to study the stem barks of Carica papaya Linn. (C. papaya; family: Caricaceae) and Tamarindus indica Linn. (T. indica; family: Fabaceae), two common plants of Bangladesh. The petroleum-ether, chloroform, and ethyl acetate extracts of the stem bark of both plants were investigated for their antibacterial activity and cytotoxicity. Materials and Methods: The antibacterial activity was evaluated using the disk diffusion method. Cytotoxicity was determined against brine shrimp nauplii. In addition, the minimum inhibitory concentration (MIC) was determined using the serial dilution technique to evaluate antibacterial potency. Results: All crude extracts of T. indica and the chloroform extract of C. papaya appeared very potent in terms of both zones of inhibition and spectrum of activity. However, all the extractives were also subjected to brine shrimp lethality bioassay for preliminary cytotoxicity evaluation. Here, the chloroform extract of C. papaya revealed the strongest cytotoxicity, LC 50 of 10.46 μg/mL. Conclusion: The stem barks of both C. papaya and T. indica show broad-spectrum antibacterial activity and may be potential sources of natural antimicrobial compounds and anticancer agents to be used in the treatment of various infectious diseases caused by resistant microorganisms and of cancer, respectively.

Antimicrobial screening of Plectranthus madagascariensis Benth. extracts

Medicinal plants have been recognized as interesting sources of natural antimicrobial compounds which may lead to new therapeutic agents. Plectranthus species are known for the occurrence of abietane diterpenoids with significant biological activity such as antimicrobial properties. [1 – 2]. Thus, it is important to screen and identify their diterpenes as potential anti-infective agents. The aim of this work was to screen the antimicrobial activity of several P. madagascariensis Benth. extracts. Several methanolic and acetonic extracts have been prepared using maceration, supercritical fluid and ultrasonic methods. All the extracts were evaluated against a panel of Gram positive (Bacillus subtillis, Mycobacterium smegmatis, Staphylococcus epidermidis, S. aureus, MRSA, MRSA “wild type”, Enterococcus faecalis and VRE) and Gram negative bacteria (Klebsiella pneumonia, Pseudomonas aeruginosa and Escherichia coli,) and yeast strains (Candida albicans and Saccharomyces cerevisiae), using the well diffusion test and the microdilution method [3]. The ultrasonic acetone extract showed the highest antimicrobial activity against B. subtillis, S. epidermidis, S. aureus and E. faecalis (MIC values of 0.98 µg.mL-1 to 3.91 µg.mL-1; including resistant MRSA and VRE strains); K. pneumonia and M. smegmatis (MIC values of < 0.49 µg.mL-1 – 31.25 µg.mL-1). Moreover, the chromatographic profile of the ultrasonic acetone extract was carried out by HPLC-DAD, using several standard compounds that were previously isolated from Plectranthus spp. [2]. The known antimicrobial rosmarinic acid and 7α-acetoxy-6β-hydroxyroyleanone were identified as the major compounds. The P. madagascariensis species seems to be a good starting vegetal material for the isolation of lead antimicrobial drugs to further being chemically modified. This study will be pursued and a bioguided fractionation and subsequent isolation of the bioactive compounds will be performed.

Chemical Composition and Antimicrobial Activity ofDaucus aureusEssential Oils from Algeria

The volatile components of Algerian Daucus aureus Desf. were investigated using a combination of analytical techniques. Analyses of essential oils obtained by hydrodistillation from the aerial parts and roots of the plant were performed using capillary GC/RI and GC/MS analysis. Seventy-one compounds were identified, constituting 90.2–96.0% of the total essential oils,. The main components from the aerial parts of the plants were germacrene D (11.3–67.2%), followed by caryophyllene oxide (0.9–9.5%), spathulenol (0.6–8.4%), ( Z)-α-santalol (1.4–6.5%), viridiflorol (0.9–5.8%), cadin-4-en-7-ol (1.5–5.6%), and τ-cadinol (1.2–5.2%). The main components of the essential oils obtained from the roots of the plant were ( Z)-α-santalol (14.1%), caryophyllene oxide (10.6%), spathulenol (9.8%), nonadecane (6.8%), and tetradecanoic acid (5.2%). The intraspecies variations of the chemical compositions of the essential oils from the aerial parts of D. aureus from 14 Algerian sample locations were investigated using statistical analysis. Essential oil samples were clustered into two groups according to their chemical compositions. This chemical variability could be attributed to growing conditions and environmental factors. The essential oils exhibited an interesting antimicrobial effect against the microorganisms tested, with MIC values in the range of 0.125–4.6 mg/mL. It is suggested that the essential oils from D. aureus may be a new potential source of natural antimicrobial compounds that could be applied in the pharmaceutical and food industries.