Antimicrobial Activity Of Extracts Research Articles

INVESTIGATION OF ANTIMICROBIAL AND ANTIVIRAL EFFECTS OF TÜRKIYE PROPOLIS WATER EXTRACTS: AN IN VITRO STUDY

Propolis is a natural bee product used as a therapeutic agent for centuries. Propolis extracts are natural resources that attract the attention of scientists looking for new components due to the insufficiency of existing drugs. In current study, antiviral and antimicrobial activity of propolis water extracts prepared from three different raw propolis samples collected from Northeast of Türkiye (Ardahan, Rize, and Trabzon) were investigated. The total flavonoid contents (TFC) and total phenolic content (TPC) of the extracts were measured. It was determined that TPC and TFC ranged from 5.87±0.36 to 20.47±1.46 mg GAE g-1, and 0.48±0.04 to 2.10±0.22 mg QUE g-1, respectively. The antimicrobial activity of the extracts against 14 microorganisms (Bacillus cereus ATCC14579, Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa ATCC 27853, Acinetobacter haemolyticus ATCC 19002, Escherichia coli ATCC 25922, Salmonella typhimurium ATCC 14028, Enterobacter aerogenes ATCC 13048, Mycobacterium smegmatis ATCC 607, Klebsiella pneumoniae ATCC 13883, Chromobacterium violaceum ATCC 12472, Candida parapsilosis ATCC 22019, and Candida albicans ATCC 10231) and their effect against the Pseudomonas aeruginosa biofilm were investigated. Additionally, anti-quorum sensing and anti-swarming activities of the extracts were tested. The antiviral activity of the extracts was examined against Herpes simplex virus type 1 (HSV-1) by MTT and qRT-PCR methods. The water extracts of propolis samples did not show antimicrobial, anti-swarming, anti-quorum sensing, and anti-viral activities. However, extracts were found to have strong anti-biofilm activities. The results show that aquatic propolis extracts can be evaluated in the treatment of biofilms.

"In vitro” antimicrobial activity of extracts from the leafy stems of Momordica charantia Linné (Cucurbitaceae) on some multi-resistant microbial strains

"In vitro” antimicrobial activity of extracts from the leafy stems of Momordica charantia Linné (Cucurbitaceae) on some multi-resistant microbial strains

The antioxidant and antimicrobial activity of ethanolic extract in roots, stems, and leaves of three commercial Cymbopogon species

BackgroundCymbopogon is a member of the family Poaceae and has been explored for its phytochemicals and bioactivities. Although the antimicrobial activities of Cymbopogon spp. extracts have been extensively studied, comprehensive analyses are required to identify promising compounds for the treatment of antimicrobial resistance. Therefore, this study investigated the antioxidant and antimicrobial properties of Cymbopogon spp. ethanolic extracts in every single organ.MethodsEthanolic extracts were obtained from three Indonesian commercial species of Cymbopogon spp., namely Cymbopogon citratus (L.) Rendle, Cymbopogon nardus (DC.) Spatf., and Cymbopogon winterianus Jowitt. The leaf, stem, and root extracts were evaluated via metabolite profiling using gas chromatography-mass spectrometry (GC–MS). In silico and in vitro analyses were used to evaluate the antioxidant and antimicrobial properties of the Cymbopogon spp. ethanolic extracts. In addition, bioactivity was measured using cytotoxicity assays. Antioxidant assays were performed using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azino-bis [3-ethylbenzothiazoline-6-sulfonic acid (ABTS) to determine toxicity to Huh7it-1 cells using a tetrazolium bromide (MTT) assay. Finally, the antimicrobial activity of these extracts was evaluated against Candida albicans, Bacillus subtilis, Staphylococcus aureus, and Escherichia coli using a well diffusion assay.ResultsGC–MS analysis revealed 53 metabolites. Of these, 2,5-bis(1,1-dimethylethyl)- phenol (27.87%), alpha-cadinol (26.76%), and 1,2-dimethoxy-4-(1-propenyl)-benzene (20.56%) were the predominant compounds. C. winterianus and C. nardus leaves exhibited the highest antioxidant activity against DPPH and ABTS, respectively. Contrastingly, the MTT assay showed low cytotoxicity. C. nardus leaf extract exhibited the highest antimicrobial activity against E. coli and S. aureus, whereas C. winterianus stem extract showed the highest activity against B. substilis. Furthermore, computational pathway analysis predicted that antimicrobial activity mechanisms were related to antioxidant activity.ConclusionsThese findings demonstrate that the leaves had strong antioxidant activity, whereas both the leaves and stems showed great antimicrobial activity. Furthermore, all Cymbopogon spp. ethanolic extracts showed low toxicity. These findings provide a foundation for future studies that assess the clinical safety of Cymbopogon spp. as novel drug candidates.

Antimicrobial, Cytotoxic and Phytochemical Analysis of Chloroform Extracts of Andrographis paniculata Root (Burm.F) and Parquetina nigrescens (Afzel) Aerial Part

The menace of antibiotic resistance especially multi-drug resistant bacteria is increasing in the clinical setting. Therefore, the study investigated antimicrobial activity and phytochemical constituents of chloroform extracts of Andrographis paniculata root (Burm.F.) and Parquetina nigrescens (Afzel) aerial part. The extracts were screened for cytotoxic activity using brine shrimp (Artemia salina) lethality bioassay. The antimicrobial activity of the extracts was tested against Citrobacter diversus, Klebsiella pneumoniae, Proteus vulgaris and Shigella sonnei using tetrazolium microtitre-plate method. Analysis of chemical components of the extracts was done on Agilent Technologies 7890A gas chromatograph system s. GC-MS analysis of A. paniculata root extract and P. nigrescens aerial part extracts revealed a total of 32 and 22 compounds, respectively. The major components identified in these two extracts were fatty acid esters, alkaloids and terpenes. The lowest MIC observed with A. paniculata extract was 6.25 μg/ml for Citrobacter diversus and 12.5 μg/ml for Klebsiella pneumoniae. The lowest MIC recorded for Parquetina nigrescens extract was 3.125 μg/ml for Citrobacter diversus, Shigella sonnei and Proteus vulgaris while it was 12.5 μg/ml for Klebsiella pneumoniae. The susceptibility was compared with a clinical antibiotic (0.02 μg/ml) which served as the positive control. P. nigrescens with LC50 of 89.75 ± 0.18 μg/ml showed higher lethal toxicity than A. paniculata with LC50 of 167.5 ± 0.21 μg/ml. The observed toxicity might be due to presence of fatty acids and alkaloids in the extracts. The extract of the plants investigated in our study showed promising antimicrobial activity. Dhaka Univ. J. Pharm. Sci. 23(1): 43-51, 2024 (June)

Antioxidant and antimicrobial activity of extracts from selected Mediterranean agro-food by-products, their mutual interaction and interaction with phenolic compounds

The by-products of Mediterranean agriculture that remain after the production of fruit wines, juices and extracts represent a large source of raw materials rich in phenolic compounds. As a contribution to the current state of knowledge, this study investigated the biological activity and phenolic composition of extracts obtained from blackberry, chokeberry and juniper by-products, as well as the interactions of the extracts in mixtures. The total phenolic content of the samples ranged from 44.42 to 250.28 mg gallic acid equivalents (GAE)/g dry extract, with the extracts from blackberry leaves and juniper needles being the highest. The highest concentration of phenolics detected by high performance liquid chromatography (HPLC) was also found in blackberry leaves (41.30 mg/g dry extract), with rutin dominating. The antioxidant activity of the samples, as measured by ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, ranged from 3.4 to 26.8 mM Trolox equivalents (TE), 15.8–58.4 mM TE and 80.1%–91.8%, respectively. Among the extract mixtures, the highest synergistic interaction was observed between blackberry leaves and juniper by-products extracts at 1:2 and 2:1 ratios. The antimicrobial activity of the extracts was tested against Gram-positive and Gram-negative foodborne pathogens and spoilage bacteria, with the lowest minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values against Staphylococcus aureus, Listeria innocua, Bacillus cereus, Campylobacter jejuni, Pseudomonas spp. and Shewanella spp. On the other hand, the antimicrobial activity of blackberry leaf extract in combination with selected phenolic compounds (vanillic acid, catechin, rutin and apigenin) showed no synergy against the tested microorganisms. Overall, the results suggest that the tested by-products extracts could be utilized for the production of natural antioxidants and antimicrobials for further use in the food industry.

Antioxidant and antimicrobial activities of <i>Cassia alata</i> (L.) Roxb. Leaves

Cassia alata is a plant of Caesalpiniaceae family used for the treatment of management infectious diseases. This work aimed at evaluating antioxidant and antimicrobial activities of hydroethanolic extract of Cassia alata leaves. The extract was obtained by the maceration of crude leaf powder (hydroethanolic 30:70). The phytochemical screening was focused on the detection of major chemical groups. The total flavonoids contents were studied using the aluminum chloride colorimetry method. The antioxidant capacity was carried out by the phosphomolybdate reduction method and by FRAP method. The antimicrobial activity of the extract was carried out by the diffusion method and the micro dilution. The extract showed the presence of phenolic compounds, flavonoids and reducing compounds. The concentration of total flavonoids of Cassia alata leaves was 70.91± 5.66 mg RE/g. The antioxidant activity by the phosphomolybdate reduction method and by the FRAP method were respectively 69.57 ± 4.83 mg AAE/g and 225.5 ± 17.32 mg FSE/g. The extract of Cassia alata has bactericidal action on Staphylococcus aureus ATCC 29213, Staphylococcus aureus SARM, Pseudomonas aeruginosa ATCC 27853 and Cutibacterium acnes ATCC 6919 and fungicidal action on Candida albicans ATCC 10231. This study shows that Cassia alata could be a source of a new antioxidant and antimicrobial agent.

Assessment of antimicrobial and anti-biofilm activities of lemongrass and bay leaf extracts on microorganisms from fermented cereal-based porridges in northern Benin

Lemongrass (Cymbopogon citratus) and bay leaf (Laurus nobilis) are condiments in food processing. This study aimed to assess the antimicrobial and anti-biofilm activities of lemongrass and bay leaf extract on the microorganisms isolated from cereal-based fermented porridges produced in northern Benin. The phytochemical components of lemongrass and bay leaf extracts were analyzed qualitatively using two solvents: water and alcohol. The antimicrobial activity of the extracts was tested using the solid media diffusion method, and the minimum concentration was determined using the microdilution method. The extracts were also evaluated for their ability to inhibit biofilm formation using qualitative assays. The two plants have different phytochemical profiles. Tannins, flavonoids, mucilage, and alkaloids were detected in both plants. Cyanogenic derivatives, O-heterosides, and genin-reduced O-heterosides were absent. L. nobilis contained anthocyanins, quinone derivatives, saponosides, reducing compounds, and free anthracenes, absent in C. citratus. The inhibition diameters ranged from 4.4 to 26.3, depending on the strains and extracts, and varied significantly. The MICs for Escherichia coli ranged from 4.5 mg/ml to 7 mg/ml, staphylococci from 3.75 mg/ml to 10 mg/ml, and lactic bacteria from 2.5 mg/ml to 4.44 mg/ml. The CMB varied between 8.125 mg/ml and 14 mg/ml for E. coli, 7.5 mg/ml to 20 mg/ml for staphylococci, and 6 mg/ml to 10 mg/ml for lactic bacteria. It is worth noting that staphylococci are the most biofilm-producing strains (80%), followed by E. coli (60%), and lactic bacteria produce less biofilm (30%). The findings of this research confirm the presence of a wide range of biological activities, including antibacterial and anti-biofilm, in the aqueous and ethanolic extracts of these two aromatic plants. Further research is required to identify and isolate the active components responsible for their medicinal properties and ascertain their operation mode.

An Endemic Species Nepeta phyllochlamys P. H. Davis: Composition of Essential Oil and Antimicrobial Activity of Extracts

This study investigates the composition of essential oil and biological activities of Nepeta phyllochlamys P. H. Davis, a local endemic species from the Lamiaceae family. Samples of N. phyllochlamys were collected from three populations, and essential oil components were compared among these populations. The main components identified in samples from three localities included caryophyllene oxide, δ-pinene, linalool, T-cadinol, α-pinene, and 14-nor-kadin-5-en-4-one (isomer A). Remarkably, the chemical content of the plant exhibited variations based on geographical regions. Although the plant showed limited antibacterial and anticandidal activities in tests, this research holds significant importance due to several factors. N. phyllochlamys is a local endemic species and part of the widely used Nepeta genus in traditional practices. Moreover, there is a scarcity of studies conducted on N. phyllochlamys, and to the best of our knowledge, no previous research has explored its phytochemical profile and antimicrobial properties. This article contributes valuable insights into the antimicrobial effects of N. phyllochlamys, shedding light on its chemical composition through the application of the GC-FID and GC-MS method.

Potential application of green extracts rich in phenolics for innovative functional foods: natural deep eutectic solvents as media for isolation of biocompounds from berries.

The health-promoting effects of berries have attracted attention due to the possible application of their extracts as functional ingredients in food products. Natural deep eutectic solvents (NADESs) are a new generation of environmentally friendly solvents for the extraction of natural products, and they are green alternatives to organic solvents, and they can improve the solubility, stability, and bioavailability of isolated biocompounds. In this study, an efficient eco-friendly method was used for the extraction of phenolic compounds from different berries: chokeberries, blueberries, and black goji berries with a range of eutectic solvents consisting of hydrogen bond acceptors (HBAs) such as choline chloride, L-proline, L-glycine, and L-lysine and hydrogen bond donors (HBDs) such as malic, citric, tartaric, lactic and succinic acids, glucose and glycerol. The obtained results indicated the ability of NADESs towards selective extraction of phenolics; the eutectic system choline chloride : malic acid showed selective extraction of anthocyanins, while choline chloride : glycerol and choline chloride : urea showed selectivity towards flavonoids and phenolic acids. The methodology for screening of the NADES extraction performance, which included chromatographic profiling via high-performance thin layer chromatography combined with chemometrics and spectrophotometric essays, allowed effective assessment of optimal eutectic solvents for isolation of different groups of phenolics. Great antioxidant and antimicrobial activities of extracts, along with the green nature of eutectic solvents, enable NADES berry extracts to be used as "green-labelled" functional foods or ingredients.

Antimicrobial activity of extracts from Ziziphus mauritiana (Rhamnaceae) bark, leaf and fruit against Staphylococcus isolated from fish

Antimicrobial activity of extracts from Ziziphus mauritiana (Rhamnaceae) bark, leaf and fruit against Staphylococcus isolated from fish

In vitro Bioactivity of Halophytic Plant Heliotropium curassavicum L. against Selected Pathogens

Heliotropium curassavicum L. was screened for antimicrobial activity against some plant and human pathogens. Plant parts of H. curassavicum, were collected from mangrove habitats of Chollangi, near Kakinada, Plant parts are dried and extracts were obtained successfully with hexane, chloroform, methanol and water, by using Soxhlet extraction apparatus. The antimicrobial activity of the plant extracts on the various test organisms, including multiple antibiotic resistant bacteria were investigated. Antimicrobial activity of the extracts was determined by the Well Diffusion Method. The results concluded that the leaf and stem extracts of H. curassavicum possess antibacterial, antifungal activities. There is a possibility of developing this plant as a source of antibacterial and antifungal agent and further investigations are necessary to identify the bioactive principles.

Bioassay-Guided Assessment of Antioxidative, Anti-Inflammatory and Antimicrobial Activities of Extracts from Medicinal Plants via High-Performance Thin-Layer Chromatography.

Natural products and their analogues have contributed significantly to treatment options, especially for anti-inflammatory and infectious diseases. Thus, the primary objective of this work was to compare the bioactivity profiles of selected medicinal plants that are historically used in folk medicine to treat inflammation and infections in the body. Chemical HPTLC fingerprinting was used to assess antioxidant, phenolic and flavonoid content, while bioassay-guided HPTLC was used to detect compounds with the highest antibacterial and anti-inflammatory activities. The results of this study showed that green tea leaf, walnut leaf, St. John's wort herb, wild thyme herb, European goldenrod herb, chamomile flower, and immortelle flower extracts were strong radical scavengers. Green tea and nettle extracts were the most active extracts against E. coli, while calendula flower extract showed significant potency against S. aureus. Furthermore, green tea, greater celandine, and fumitory extracts exhibited pronounced potential in suppressing COX-1 activity. The bioactive compounds from the green tea extract, as the most bioactive, were isolated by preparative thin-layer chromatography and characterized with their FTIR spectra. Although earlier studies have related green tea's anti-inflammatory properties to the presence of catechins, particularly epigallocatechin-3-gallate, the FTIR spectrum of the compound from the most intense bioactive zone showed the strongest anti-inflammatory activity can be attributed to amino acids and heterocyclic compounds. As expected, antibacterial activity in extracts was related to fatty acids and monoglycerides.

Anticancer and antimicrobial evaluation of extract from brown algae Hormophysa cuneiformis.

We investigated the antimicrobial and anticancer properties of an ethanol crude extract of Red Sea brown alga (Hormophysa cuneiformis) from Egypt. Extraction was achieved by mixing 100 g of sample powder with absolute ethanol, incubating at 37 °C overnight in a shaking incubator, and then collecting the extract. The extract's antimicrobial activity was tested using a well diffusion assay against the tested pathogens (Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Candida albicans) in comparison to commercial antibiotics. Anticancer activity was assessed using MTT assay on MCF-7, HepG-2, and HEP-2 cell lines. The anticancer mechanism of action against the HepG-2 cell line was investigated using cell cycle analysis, Annexin V, and antioxidant enzymes, in addition to transmission electron microscopy. GC-MS phytoconstituent profile of the extract was dominant with fatty acids. A broad antimicrobial effect against all the pathogenic isolates of E. coli, S. aureus, B. subtitles, and C. albicans was demonstrated, especially at the high concentration in comparison to commercial antibiotics. The extract could inhibit the growth of the tested cell lines. We observed the most significant effect on HepG-2 cells, and the concentration of the extract played a role in the level of inhibition (IC50 of 44.6 ± 0.6 µg/ml). The extract had negligible effects on Vero normal cell lines at the lower concentration, with slight toxicity (90.8% viability) at the highest concentration (500 µg/ml). At this same concentration, the extract caused 80-92% inhibition of the cancer cell lines. The extract appears to have demonstrated promising effects on cancer cells. It induces programmed cell death (apoptosis), arrests the cell cycle, and affects the oxidative/antioxidant balance within the cells, potentially leading to the suppression or elimination of cancer cells. These findings are encouraging and may have implications for cancer treatment or further research in this area. More action of extract was seen against bacteria than fungi, with a wide antibacterial impact against all of the tested isolates, notably at the high concentration in comparison to conventional antibiotics. According to the findings, H. cuneiformis may be a valuable source of chemicals that are both antimicrobial and anticancer.

Actividad antimicrobiana de extractos de ramas de Hedyosmum cuatrecazanum Occhioni (Chloranthaceae)

The genus Hedyosmum (Chloranthaceae) consists of 45 species. In Ecuador, this genus presents 16 endemic species of the high cloud forest and subpáramos of the country's south. The objective was to determine the antimicrobial activity of hexanic and ethanolic extracts from branches of Hedyosmum cuatrecazanum Occhioni., from the Ecuadorian Andes against microorganisms of clinical importance. The fresh branches of H. cuatrecazanum Occhioni. They were obtained from the natural forest of Jacarón, province of Chimborazo - Ecuador; they were dried (in an oven at 38ºC x 3 days) and then crushed. Plant material (200 gr) was placed in Erlenmeyer flasks (1000 mL with 500 mL) of Hexane or Ethanol, 72h (19oC+/-2). Subsequently, each extract was filtered and subjected to rotary evaporation (55°C), and stored at (4°C) in the dark. The antimicrobial activities of the extracts were studied by diffusion in agar and minimum inhibitory concentration, starting from dilutions with dimethyl sulfoxide. Both extracts showed activity against most Gram-negative bacteria, but only against the Gram-positive Staphylococcus aureus. Candida strains showed variable susceptibility to hexanic extracts but not to ethanolic ones. The studied extracts of Hedyosmum cuatrecazanum Occhioni., show variable antimicrobial potential against microorganisms of clinical importance. Keywords: Hedyosmum cuatrecazanum Occhioni, antibacterials, antifungals, extracts, minimum inhibitory concentration.

Nutritional, Antioxidant, Antimicrobial, and Anticholinesterase Properties of Phyllanthus emblica: A Study Supported by Spectroscopic and Computational Investigations.

Dietary fruits and vegetables play a vital role as food and drugs and are the main sources of antioxidant defences against degenerative diseases, such as brain dysfunctions, cardiovascular diseases, immune system deteriorations, and cancers, brought on by oxidative damage. Phyllanthus emblica is a significant herbal remedy used in conventional medicine to recover lost strength and power. In this research, the potential value of Phyllanthus emblica as a food and drug is researched. The total phenolic, total flavonoid, and total tannin contents as well as the nutritional value, vitamin C, vitamin E, and mineral contents of different organs of P. emblica were evaluated. The antioxidant and antimicrobial activities of extracts and fractions of different organs of P. emblica were determined. A total of eleven flavonoids, simple phenolic, tannin-related phenolic, and tannin molecules were isolated from a hydroalcoholic extract of the leaves and fruits. The structures were identified by spectroscopic data and comparison with the literature values as gallic acid (1), naringenin 7-O-(6″-O-galloyl)-β-D-glucopyranoside (2), 3,3'-di-O-methyl ellagic acid-4'-O-β-d-glucopyranoside (3), 1-O-galloyl glycerol (4), 1,6-di-O-galloyl-β-d-glucopyranoside (5), flavogallonic acid bislactone (6), corilagin (7), ethyl gallate (8), urolithin M5 (9), (E)-p-coumaroyl-1-O-β-d-glucopyranoside (10), and 1,2,4,6-tetra-O-galloyl-β-d-glucopyranoside (11). Among them, compounds 3 and 10 are first isolated from the plant. Molecular docking was performed to investigate the comparative interactions between positive controls (galantamine and donepezil) and selected compounds utilizing acetylcholinesterase (4EY7) as a target receptor. Results exhibited the potency of these compounds against the target receptor. In summary, P. emblica has a wealth of minerals, vitamins C and E, and polyphenolic phytochemicals that may work together to treat infectious disease, prevent and/or treat oxidative-damage-related illnesses including Alzheimer's disease.

Analysis of the main bioactive compounds from Ocimum basilicum for their antimicrobial and antioxidant activity.

The interest in bioactives especially from botanicals to treat vancomycin-resistant enterococcal (VRE) infections is increased. Many species of Ocimum have a long history in folk medicinal and food industries. Nevertheless, their bioactive compounds remain unexplored. This study is aimed to assess the antimicrobial and antioxidant activity of basil leaf extract prepared using ethanol, methanol, and water. The ethanol and methanol extract have all the phytochemicals (alkaloids, flavonoids, phenolic compounds, tannins, saponins, quinones, carbohydrates, and proteins) except steroids and terpenoids. In addition to steroids and terpenoids, tannin was also absent in the aqueous extract. Total phenolic and flavonoid content was high in ethanol and followed by methanol and aqueous extract. Similarly, ethanol and methanol extract showed strong antimicrobial activity against VRE and MTCC strains at a concentration of 20mg/mL than aqueous extract. Among the 10 indicators, Staphylococcus aureus is highly susceptible to ethanol extract at a concentration of 8mg/mL and followed by other MTCC strains. Vancomycin-resistant enterococci pathogens were inhibited at the minimum inhibitory concentration of 14, 16, and 20mg/mL of ethanol, methanol, and aqueous extract. Further, on the basis of determining the absorbing material (nucleic acid and protein) at 260nm and scanning electron microscopic, it was confirmed that the loss of cell membrane integrity and cell membrane damage were the effective mechanisms of plant extract antimicrobial activity. All three solvents have shown remarkable antioxidant activity. Gas chromatography-mass spectrometry analysis of basil leaves ethanol extract identified 19 compounds with various therapeutic and food applications.

Antimicrobial Activity of Psidium guajava Aqueous Extract against Sensitive and Resistant Bacterial Strains.

The inappropriate use of antimicrobials, along with environmental conditions, can lead to the emergence of resistant microorganisms. The use of phytopharmaceuticals and herbal medicines has a positive impact and represents a promising alternative. Psidium guajava extracts have been widely reported to have antimicrobial potential; however, studies reporting their activity against resistant bacterial strains are scarce. Because of the emerging resistance, the aim of this study was to analyze the antimicrobial capacity of the aqueous extract of guava leaves against wild-type and resistant bacterial strains. The aqueous extract obtained from the leaves of P. guajava was evaluated by HPLC for the content of total phenolics and tannins, antioxidant activity, and chemical composition. The antimicrobial activity of the extracts was analyzed by the disk diffusion and broth microdilution methods. The results of the chemical analysis of the extracts showed total phenolics content of 17.02 ± 6.87 mg/g of dry extract, total tannin content of 14.09 ± 1.20 mg of tannic acid equivalents/g of dry extract, and moderate antioxidant capacity with an EC50 value of 140 µg/mL. Flavonoids are the major compounds (rutin, hesperidin, and quercetin), followed by phenolic acids. Disk diffusion test results showed the presence of inhibition halos for Gram-positive bacteria (Staphylococcus aureus, sensitive and resistant; Staphylococcus pseudintermedius, sensitive and resistant; and Streptococcus spp., beta-hemolytic), while for Gram-negative bacteria (Escherichia coli, sensitive and resistant), there was no inhibition in the tested concentration range. The Minimal Inhibitory Concentration was 6.8 mg/mL for all Gram-positive strains evaluated. The present study demonstrated the antimicrobial activity of the aqueous extract of P. guajava against sensitive and resistant Gram-positive bacteria. The better antimicrobial activity found in the present study compared with previously reported activity should be highlighted and may be related to the higher concentration of total phenolics present in the tested extract. Moreover, the content of tannins found suggests a species with high quality that produces tannins. These new findings suggest an innovative profile regarding therapeutic resources that can be adopted to combat resistant microbial strains.

GC-MS profile and antimicrobial activities of extracts from root of Senna occidentalis Linn.

Abstract We considered the extraction of plant materials from Senna occidentalis root, and its fractionation monitored by bioassay towards isolating its bioactive principles. Pulverized root sample of Senna occidentalis (fam. leguminaceae) was extracted with methanol using a maceration method. The crude methanol extract (MSo) 6.06 g was partitioned into petroleum ether and ethyl acetate to yield their respective fractions viz: petroleum ether fraction (1.20 g), ethyl acetate fraction (1.86 g) and methanol fraction (2.92 g). The crude methanol extract was analyzed using phytochemical screening, infrared spectroscopy, and gas chromatography/mass spectrometry while the fractions were examined for antimicrobial properties. Phytochemical screening indicated the presence of tannins, phenolics, alkaloids, flavonoids, saponins, cardiac glycosides, phlobatannin, and absence of steroids. The infrared spectrum revealed a broad absorption band at 3437.26 cm-1 due to O-H symmetric stretch in polymeric alcohols, and absorption frequency of 1640.51cm-1 of moderate intensity due to C=O stretch. Enols are easily identified by the broad H-bonded O-H stretch absorption and low C=O stretch frequency as in β-keto enolic esters and phenol acetates, -CO-O-C=C-, (1690-1650 cm-1). Gas chromatography/mass spectrometry identified the presence of ten compounds including n-hexadecanoic acid (23.76%), linoleic acid (1.64%), E-9-tetradecenoic acid (4.88%), octadecanoic acid, 2-(2 hydroxyethoxy) ethyl ester (6.24%) and E-2-octadecadecen-1-ol (13.74%). Similar broad spectrum antimicrobial activities were manifested by methanol and ethyl acetate fractions. Escherichia coli and Bacillus cereus were the most susceptible with the highest zone of inhibition of 30 mm and 28 mm respectively at minimum inhibition concentration of 1.35 x103 μg/ml. The methanol fraction has the highest potency against the tested pathogens whereas the petroleum ether fraction exhibited activity only on gram negative pathogens. The antimicrobial activities observed in these fractions suggest the presence of active chemical components in the crude methanol root extract of Senna occidentalis thus provides a potential source of novel antimicrobial agents. Further work is however, required to isolate and characterize these bioactive principles.

Antimicrobial activity, cytotoxicity, and qualitative phytochemical composition of aqueous and methanolic leaf extracts of Physalis peruviana L. (Solanaceae)

Background: The high morbidity and mortality associated with microbial infections and the ineffectiveness of conventional antibiotics due to inappropriate use and resistance warrant alternative stratagems. Aim: We investigated the antimicrobial, cytotoxicity, and qualitative phytochemical composition of the aqueous and methanolic leaf extracts of Physalis peruviana L. (Solanaceae) based on its ethnomedicinal information. Methods: The antimicrobial activity of the extracts was investigated using the disk diffusion technique. The brine shrimp lethality assay method was used to determine the cytotoxicity of the study extracts on brine shrimp nauplii. Qualitative phytochemistry of the study extracts was performed using standard procedures. Results: The two extracts did not possess antimicrobial activity against P. aeruginosa and were either inactive or slightly inactive against the other microbes at concentrations of ≤ 50 µg/ml. Notably, the aqueous extract exhibited high to very high activities against E. coli and S. aureus and very high to remarkable activities against B. cereus. The methanolic extract showed remarkable activity at concentrations of ≥200 µg/ml against E. coli, moderate to very high against S. aureus, high to very high against B. cereus, and moderate to high against C. albicans. The aqueous extract's minimum inhibitory concentrations (MICs) were 50 μg/ml (E. coli and B. cereus), 100 μg/ml (S. aureus), and 200 μg/ml (C. albicans). The minimum bactericidal concentration concentrations (MBCs) of the aqueous extract were 100 μg/ml (E. coli and B. cereus), 200 μg/ml (S. aureus), while the minimum fungicidal concentration (MFC) for C. albicans was 400 μg/ml. The MICs of the methanolic extract were 25 μg/ml for E. coli, S. aureus, and B. cereus and 100 μg/ml for C. albicans, and the MBCs were 100 μg/ml for E. coli, S. aureus, and B. cereus, and the MFC for C. albicans was 200 μg/ml. The aqueous was non-toxic, while the methanolic extract was slightly toxic to brine shrimp nauplii, indicating their relative safety. Various phytochemicals were detected in the study extracts, depicting broad pharmacologic activity, including antimicrobial activity. Conclusion: The aqueous and methanolic leaf extracts of P. peruviana may serve as a source of efficacious and safe novel antimicrobial agents upon further evaluation.

Extraction and optimization of phenolic compounds from butterbur plant (Petasites hybridus) by ultrasound-assisted extraction and determination of antioxidant and antimicrobial activity of butterbur extracts

Butterbur (Petasites hybridus), which is a perennial herb native to Europe, Asia and North America, is used as food in the Black Sea region of Turkey. In this study, it was aimed to identify the natural microflora of the root, stem and leaf parts of the butterbur plant, to optimize the extraction of phenolic compounds in these parts by ultrasound-assisted extraction (UAE) using the response surface methodology (RSM), and to determine the antioxidant and antimicrobial activities of these extracts. For this purpose, the effects of temperature (30–70 °C), extraction time (30–60 min) and ethanol concentration (0–70%) on total phenolic compounds (TPC) of phenolic extracts obtained from the butterbur plant parts were determined. As a result of the extractions carried out at optimum conditions, TPC (4.73, 0.64 and 3.78 μg GAE/mg extract), ABTS (17.57, 7.57 and 12.84 µg TE/mg extract), DPPH (2.51, 1.84 and 2.27 µg TE/mg extract) and FRAP (3.64, 2.95 and 3.14 µg TE/mg extract) values of the extracts obtained from root, stem and leaf were determined. Antimicrobial activity of the root, stem and leaf extracts were investigated on Escherichia coli O157:H7, Salmonella Typhimurium, Bacillus cereus, Staphylococcus aureus, Lactobacillus plantarum and Lactobacillus brevis microorganisms by the 96-well microtiter plate method and also disc diffusion method. Minimum inhibition concentration (MIC) values of the extracts ranged between 0.39 and 87.50 mg/mL for all extracts and all tested microorganisms, while inhibition zone diameters ranged between 6.05 and 20.30 mm. In conclusion, extracts obtained from the butterbur plant can extend the shelf life of food products due to their antimicrobial activities.