In vitro efficacy of bioactive extracts of 15 medicinal plants against ESβL-producing multidrug-resistant enteric bacteria

The Occurrence, Uses, Biosynthetic Pathway, and Biotechnological Production of Plumbagin, a Potent Antitumor Naphthoquinone

Plumbagin is an important naphthoquinone with potent anticancer properties besides multitudinous uses in healthcare. It is produced in a limited number of species and families but mostly in the roots of Plumbaginaceae family members. The biosynthetic pathway and the genes that regulate plumbagin synthesis are not completely known, but details of these are being revealed. Several species, including Plumbago, Drosera, and others, are being uprooted for the extraction of plumbagin by pharmaceutical industries, leading to the destruction of natural habitats. The pharmaceutical industry is therefore facing an acute shortage of plant material. This necessitates enhancing the accumulation of plumbagin using suspensions and hairy roots to meet market demands. Many factors, such as the aggregate size of the inoculum, stability of the culture, and the sequential effects of elicitors, immobilization, and permeabilization, have been demonstrated to act synergistically and markedly augment plumbagin accumulation. Hairy root cultures can be used for the large-scale production, growth, and plumbagin accumulation, and the exploration of their efficacy is now imperative. The secretion of compounds into the spent medium and their in situ adsorption via resin has remarkable potential, but this has not been thoroughly exploited. Improvements in the quality of biomass, selection of cell lines, and production of plumbagin in bioreactors have thus far been sporadic, and these parameters need to be further exploited. In this review, we report the advances made relating to the importance of stable cell line selection for the accumulation of compounds in long-term cultures, hairy root cultures for the accumulation of plumbagin, and its semicontinuous production via total cell recycling in different types of bioreactors. Such advances might pave the way for industrial exploitation. The steps in the biosynthetic pathway that are currently understood might also aid us in isolating the relevant genes in order to examine the effects of their overexpression or heterologous downregulation or to edit the genome using CRISPR-Cas9 technology in order to enhance the accumulation of plumbagin. Its potential as an anticancer molecule and its mode of action have been amply demonstrated, but plumbagin has not been exploited in clinics due to its insolubility in water and its highly lipophilic nature. Plumbagin-loaded nanoemulsions, plumbagin-silver, or albumin nanoparticle formulations can overcome these problems relating to its solubility and are currently being tried to improve its bioavailability and antiproliferative activities, as discussed in the current paper.

Phytochemical screening, UPLC analysis, evaluation of synergistic antioxidant and antibacterial efficacy of three medicinal plants used in Kinshasa, D.R. Congo

Plant extracts are used worldwide due to their biologically active compounds, which support food preservation and help combat various diseases through their antimicrobial and antioxidant properties. In the capital city of the Democratic Republic of the Congo, an ethnobotanical survey revealed the use of Dysphania ambrosioides (L.) Mosyakin & Clemants, Ocimum gratissimum L. and Tetradenia riparia (Hochst.) Codd, often in combination, for treating oral microbial diseases. While these plants have been widely studied individually; their combined potential has not been investigated. The present research aims to explore the phytochemical composition, the synergistic antimicrobial, and antioxidant potential of different extracts from these three mentioned plants. Phytochemical composition of the decocted and percolated extracts from the three plants was determined using qualitative analysis and the ultra-performance liquid chromatography quadrupole time of flight tandem mass spectrometry (UPLC-QTOF-MS). Antimicrobial activity was assessed using the broth dilution method, while antioxidant activity was evaluated using the DPPH method. For the antimicrobial studies, the decocted and percolated extracts were tested against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Qualitative phytochemical analysis revealed the presence of alkaloids, saponins, flavonoids, iridoids, and anthraquinones in all the plant extracts. The methanolic extract of T. riparia exhibited the highest phenolic content (299.146 ± 0.143 mg GAE/g extract), while O. gratissimum had the highest flavonoid content (138.256 ± 0.277 mg QE/g extract). UPLC analysis identified several metabolites in the plant extracts including rosmarinic acid, cirsimaritin, xanthomicrol and kaempferol derivatives. Rosmarinic acid was consistently identified across all the plant extract combinations, while other flavonoids such as apigenin 7-glycosides, kaempferitin and luteolin 7-O-glucoside, were detected in specific plant extract combinations. The decocted plant extracts exhibited higher antioxidant activity than the percolated extracts, with O. gratissimum showing the highest antioxidant activity (11.744 ± 0.584 µg/mL), followed by T. riparia (12.916 ± 0.972 µg/mL). The extract combinations from O. gratissimum and T. riparia demonstrated synergistic antioxidant activity (CI = 0.57). Amongst all extracts, the highest antibacterial activity was observed in the decocted extracts of O. gratissimum and T. riparia against S. aureus (MIC = 500 µg/mL), with their combination showing additive antibacterial activity (FICI = 1). The aim of this study was primarily to evaluate the combinatory potential of these three plants as reliable sources of antimicrobials and antioxidants for the treatment of various microbial diseases in the future. The study provides evidence of the synergistic antioxidant and antibacterial potential of O. gratissimum and T. riparia. These results suggest that these plant extracts are promising sources of natural antimicrobial and antioxidant agents, with potential application in the pharmaceutical and food industries for combating several infectious diseases.

Antimicrobial Activity of Tea and Agarwood Leaf Extracts Against Multidrug-Resistant Microbes

Emerging multidrug-resistant (MDR) strains are the main challenges to the progression of new drug discovery. To diminish infectious disease-causing pathogens, new antibiotics are required while the drying pipeline of potent antibiotics is adding to the severity. Plant secondary metabolites or phytochemicals including alkaloids, phenols, flavonoids, and terpenes have successfully demonstrated their inhibitory potential against the drug-resistant pathogens. In quest of potential phytochemicals, we selected tea (Camellia sinensis) and agarwood (Aquilaria malaccensis) leaves for antimicrobial activity. Fresh tea leaves were collected in three varieties, namely, BT-6, BT-7, and BT-8, including green tea (nonfermented tea), black tea (fully fermented tea), and agarwood leaves collected from Sylhet region of Bangladesh. This study is aimed at analyzing the phytochemical constituency and antimicrobial activity of tea and agarwood leaf extracts and analyzing if there is a combined effect or synergistic activity against multidrug-resistant pathogens. The antimicrobial activity of tea and agarwood leaf extracts was analyzed against MDR pathogenic bacteria and fungus. Qualitative and quantitative phytochemical constituency profiling of these six leaf extracts was evaluated, and preliminary screening exhibited that most of the leaves contained diverse groups of metabolites (alkaloids, tannin, flavonoids, glycosides, saponins, etc.). The highest amounts of TPC (total phenolic content) (110.16 ± 0.48 μg/mg) were found in BT-7 in ethanol extracts, and BT-8 in methanol extracts possessed the highest (128.1 ± 0.43 μg/mg) TFC (total flavonoid content). Notably, green tea showed remarkable results in TPC and TFC. In antioxidant scavenging activity, BT-7 and green tea showed significant IC50 values which were 13.23 and 20.75 mg/mL, respectively. In antimicrobial assays, both 50 μL of each tea and agarwood leaf extract antimicrobial activities were examined against 50 μL of each bacterial and fungal culture. In synergistic activity, 50 μL of each type of leaf extracts was poured over the commercial antibiotics to evaluate their synergism, additive, or antagonism activity against the multidrug-resistant pathogens. In the antimicrobial activity test, green tea showed a maximum diameter (22.0 ± 1.1 mm) zone of inhibition against Klebsiella pneumoniae whereas BT-8 showed 22.0 ± 2.5 mm against Pseudomonas aeruginosa. Indeed, fresh tea BT-6 and BT-7 both showed remarkable zone of inhibition against the selected microbes including Gram-negative and Gram-positive bacteria. Besides, leaf extract also showed antimicrobial activity against pathogenic fungus Mucor circinelloides. Aiming to increase antibiotic resistance efficacy, synergistic activities were evaluated among leaf extracts and antibiotics against the selected pathogens where synergism, antagonism, and additive results were noted. Combination of BT-8 extracts with antibiotics (ceftiofur) showed the highest synergism nearly 36 mm of the zone of inhibition against Escherichia coli. Additionally, green tea with gentamicin and erythromycin also showed remarkable synergism 35 and 33 mm against Mucor circinelloides and E. coli, respectively. Tea and agarwood leaves grown in Bangladesh possess high antioxidant activity, promising antibacterial and antifungal activity, thus might provide a potential source for drug discovery.

Bioactivity screening and molecular identification of Anchusa milleri L. sunflower crud extract for antioxidant, antiviral, antimicrobial, and anticancer properties

The current study evaluates hot water A. milleri sunflower extracts at 40 °C temperature (AMSE40) for their antibacterial, anti-biofilm, antiviral and anticancer activities. AMSE40 exhibited excellent antioxidant activity with an IC50 of 1.17 mg/mL (ascorbic acid) and was found to be rich in phytochemical compounds such as alkaloids, flavonoids, phenolics, saponins, and tannins, with concentrations of 1.23%, 351.60 mg/g, 152.50 mg/g, 0.98%, and 146.35 mg/g, respectively. AMSE40 showed strong antibacterial and anti-biofilm activity against four multidrug-resistant isolates, comprising E. faecalis, S. aureus, P. aeruginosa, and K. pneumonia with minimum bactericidal concentrations (25 mg/mL) and minimum inhibitory concentrations (12.5 mg/mL) for all isolates. The AMSE40 (62.5 µg/mL) showed antiviral efficacy against CoxB4 (9.1%) and HSV-1 (34.4%). Additionally, AMSE40 induced DNA fragmentation in liver cell lines, indicating cell death. The cytotoxic concentration of AMSE40 had a mild impact on Vero (283.2 µg) and HepG2 cells (76.4 µg). A. milleri has the potential to serve as a natural and eco-friendly source for innovative pharmaceutical and medical applications.

Screening of antimicrobial activity of Ilex paraguariensis St. Hil. leaf extracts against carbapenemase-producing bacteria

I. paraguariensis St. Hil. is a south American species of agronomic interest with studies supporting its medicinal properties. As the investigation of active ingredients with antimicrobial effect from medicinal plants is a suitable approach to the current antibacterial resistance problem, the aim of the present study was to determine the antibacterial activity of yerba mate ethanolic extracts against carbapenemase-producing gram-negative bacteria (reference strains and clinical isolates). Extracts showed antibacterial activity against Klebsiella pneumoniae ATCC® BAA-2342™ (KPC producing), Providencia rettgeri (NDM producing), Pseudomonas aeruginosa (MBL producing) and P. aeruginosa (VIM producing) at the concentrations tested. The Minimal-Inhibitory-Concentration and Minimal-Bactericidal-Concentration values ranged between 1 and 32 mg.ml-1 for the reference strains, and between 0.125 and 1 mg.ml-1 for the clinical isolates. The MBC/MIC index characterized the extracts as bactericidal. The combinations of commercial antibiotics and extracts showed a synergistic action on the reference strains studied. The lethal concentration 50 obtained using the Artemia salina toxicity assay were higher than 1 mg.ml-1 for all the extracts, indicating a low toxicity. The in vitro activity and low toxicity suggest that ethanolic I. paraguariensis leaf extracts constitute an outstanding source for new antibacterial compounds, and further studies should be carried out to understand their mechanism of action.

Antibacterial activity and phytochemical screening of traditional medicinal plants most preferred for treating infectious diseases in Habru District, North Wollo Zone, Amhara Region, Ethiopia

Ethiopia's healthcare system relies on traditional medicinal practices that use medicinal plants to treat human and livestock ailments. However, the lack of empirical validation regarding the efficacy of these treatments against specific infectious diseases necessitates rigorous scientific investigations. The objective of this study was to investigate the antibacterial activity and phytochemical screening on five selected medicinal plant species, namely Solanum somalense Franchet., Verbascum sinaiticum Benth., Rumex nervosus Vahl, Withania somnifera (L.) Dunal and Calpurnia aurea (Ait.) Benth. The plants were first identified jointly with local informants and later considering mainly their high informant consensus and fidelity level values for their efficacy in treating infectious diseases in the area. Ethanol and aqueous extracts were prepared from the plant materials, and their antibacterial activities were evaluated against standard bacterial strains, representing both gram-positive and gram-negative types. To assess the antibacterial activity of the extracts, the minimum inhibitory concentration (MIC) was determined using the broth dilution method. Additionally, phytochemical screening was performed using standard qualitative tests to identify various secondary metabolites. The results indicated antibacterial efficacy in the ethanol extracts of S. somalense, W. somnifera, and C. aurea against particular bacterial strains (S. somalense against S. agalactiae with MIC of 1.5 mg/mL; W. somnifera against S. aureus and E. coli, with MIC of 2 mg/mL; C. aurea against E. coli and K. pneumoniae, with MICs of 3 mg/mL and 3.5 mg/mL, respectively). The results of the phytochemical screening indicated the presence of steroids, alkaloids, flavonoids, saponins, and terpenoids. The selected medicinal plants demonstrated promising antibacterial activity against certain bacterial strains. The current findings support the long-standing claim of the traditional medical system of the study area for their continued use of these plants in their treatment of infectious diseases. Further investigation is required to isolate the responsible active compounds and characterize the constituents and description of their antibacterial effect for possible use in areas where these infectious diseases are major health problems.

Artemisia brevifolia Wall. Ex DC Enhances Cefixime Susceptibility by Reforming Antimicrobial Resistance

(1) Background: A possible solution to antimicrobial resistance (AMR) is synergism with plants like Artemisia brevifolia Wall. ex DC. (2) Methods: Phytochemical quantification of extracts (n-hexane (NH), ethyl acetate (EA), methanol (M), and aqueous (Aq)) was performed using RP-HPLC and chromogenic assays. Extracts were screened against resistant clinical isolates via disc diffusion, broth dilution, the checkerboard method, time-kill, and protein quantification assays. (3) Results: M extract had the maximum phenolic (15.98 ± 0.1 μg GAE/mgE) and flavonoid contents (9.93 ± 0.5 μg QE/mgE). RP-HPLC displayed the maximum polyphenols in the M extract. Secondary metabolite determination showed M extract to have the highest glycosides, alkaloids, and tannins. Preliminary resistance profiling indicated that selected isolates were resistant to cefixime (MIC 20-40 µg/mL). Extracts showed moderate antibacterial activity (MIC 60-100 µg/mL). The checkerboard method revealed a total synergy between EA extract and cefixime with 10-fold reductions in cefixime dose against resistant P. aeruginosa and MRSA. Moreover, A. brevifolia extracts potentiated the antibacterial effect of cefixime after 6 and 9 h. The synergistic combination was non- to slightly hemolytic and could inhibit bacterial protein in addition to cefixime disrupting the cell wall, thus making it difficult for bacteria to survive. (4) Conclusion: A. brevifolia in combination with cefixime has the potential to inhibit AMR.

Major phenolic compounds, antioxidant, antimicrobial, and cytotoxic activities of Selinum carvifolia (L.) collected from different altitudes in India

Antibiotic resistance poses a serious threat to public health, raising the number of diseases in the community. Recent research has shown that plant-derived phenolic compounds have strong antimicrobial, antifungal, and cytotoxic properties against a variety of microorganisms and work as great antioxidants in such treatments. The goal of the current work is to evaluate the anticancerous, antibacterial, antifungal, antioxidant, and cytotoxicity activities in the extracts of the different plant parts (leaves, stems, and roots) of S. carvifolia (L.) L. This is a medicinally important plant and has been used for different kinds of diseases and ailments such as hysteria and seizures. The phenolic compounds from the different plant parts were analyzed using HPLC and the following were found to be present: chlorogenic acid, gallic acid, rutin, syringic acid, vanillic acid, cinnamic acid, caffeic acid, and protocatechuic acid. Gallic acid was found to have the highest concentration (13.93 mg/g), while chlorogenic acid (0.25 mg/g) had the lowest. The maximum TPC value, which ranged from 33.79 to 57.95 mg GAE/g dry extract weight, was found in the stem. Root extract with 9.4 mg RE/g had the greatest TFC level. In the leaf and stem extracts, the RSC ranged from 0.747 mg/mL to 0.734 mg/1 mL GE/g dry extract weight, respectively. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to measure in vitro antioxidant activity. In a concentration-dependent way, promising antioxidant activity was reported. Moreover, 3,5-dinitrosalicylic acid (DNSA) and the Folin-Ciocalteu phenol reagent technique were used to determine reducing sugar content and total phenolic content, respectively. Antibacterial activity against eight strains (MIC: 250-1,000 μg/mL) was analyzed, and the stem extract exhibited maximum activity. Antifungal activity was also assessed, and potent activity was reported especially in the extract obtained from the stem. Cytotoxicity was evaluated using an MTT assay in the A549 cell line, where different doses (0.0625, 0.125, 0.25, 0.5, and 1 mg/mL) of leaf, root, and stem extracts were used. Treatment with these extracts reduced the cell viability, indicating that S. carvifolia may possess anticancer potential, which can be of great therapeutic value.

A comprehensive review on traditional uses, phytochemistry and pharmacological properties of Paeonia emodi Wall. ex Royle: current landscape and future perspectives

Paeonia emodi Wall. ex Royle is commonly known as Himalayan paeony has great importance as a food and medicine. The practice of Paeonia emodi Wall. ex Royle is very ancient and it is conventionally used for a wide range of illnesses in the folk system of medicine because of its wide beneficial phytochemical profile. The main purpose of the current review was the synthesis of recent data on botany, ethnopharmacology, phytochemistry and potential pharmacological mechanisms of action of Paeonia emodi Wall. ex Royle, thus offering new prospects for the development of new adjuvant natural therapies. Using scientific databases such as PubMed/MedLine, Scopus, Web of Science, ScienceDirect, Google Scholar, Springer, and Wiley, a comprehensive literature search was performed for Paeonia emodi Wall. ex Royle. For searching, we used the next MeSH terms: "Biological Product/isolation and purification", "Biological Products/pharmacology", "Drug Discovery/methods", "Ethnopharmacology, Medicine", "Traditional/methods", "Paeonia/chemistry", "Plant Extracts/pharmacology", "Phytochemicals/chemistry", "Phytochemicals/pharmacology", "Plants, Medicinal". The results of the most recent studies were analyzed and the most important data were summarized in tables and figures. Phytochemical research of Paeonia emodi Wall. ex Royle has led to the isolation of triterpenes, monoterpenes, phenolic acids, fatty acids, organic compounds, steroids, free radicals and some other classes of primary metabolites. In addition, diverse pharmacological activities like antibacterial, antifungal, anticoagulant, airway relaxant lipoxygenase and beta-glucuronidase inhibiting activity, radical scavenging activity, phytotoxic and insecticidal activities have been reported for Paeonia emodi Wall. ex Royle. Different bioactive compounds of Paeonia emodi Wall. ex Royle has proven their therapeutic potential in modern pharmacological and biomedical research to cure numerous gastrointestinal and nervous disorders. In future, further in vitro and in vivo therapeutic studies are required to identify new mechanisms of action, pharmacokinetics studies, and new pharmaceutical formulations for target transport and possible interaction with allopathic drugs. Also, new research regarding quality evaluation, toxicity and safety data in humans is needed.

Phytochemistry and Pharmacology of Medicinal Plants Used by the Tenggerese Society in Java Island of Indonesia

The archipelagic country of Indonesia is inhabited by 300 ethnic groups, including the indigenous people of Tengger. Based on the reported list of medicinal plants used by the Tengger community, we have reviewed each of them for their phytochemical constituents and pharmacological activities. Out of a total of 41 medicinal plants used by the Tengerrese people, 33 species were studied for their phytochemical and pharmacological properties. More than 554 phytochemicals with diverse molecular structures belonging to different chemical classes including flavonoids, terpenoids, saponins and volatiles were identified from these studied 34 medicinal plants. Many of these medicinal plants and their compounds have been tested for various pharmacological activities including anti-inflammatory, antimicrobial, wound healing, headache, antimalarial and hypertension. Five popularly used medicinal plants by the healers were Garcinia mangostana, Apium graveolens, Cayratia clematidea, Drymocallis arguta and Elaeocarpus longifolius. Only A. graviolens were previously studied, with the outcomes supporting the pharmacological claims to treat hypertension. Few unexplored medicinal plants are Physalis lagascae, Piper amplum, Rosa tomentosa and Tagetes tenuifolia, and they present great potential for biodiscovery and drug lead identification.

The Antimicrobial Potential of the Neem Tree Azadirachta indica

Azadirachta indica (A. Juss), also known as the neem tree, has been used for millennia as a traditional remedy for a multitude of human ailments. Also recognized around the world as a broad-spectrum pesticide and fertilizer, neem has applications in agriculture and beyond. Currently, the extensive antimicrobial activities of A. indica are being explored through research in the fields of dentistry, food safety, bacteriology, mycology, virology, and parasitology. Herein, some of the most recent studies that demonstrate the potential of neem as a previously untapped source of novel therapeutics are summarized as they relate to the aforementioned research topics. Additionally, the capacity of neem extracts and compounds to act against drug-resistant and biofilm-forming organisms, both of which represent large groups of pathogens for which there are limited treatment options, are highlighted. Updated information on the phytochemistry and safety of neem-derived products are discussed as well. Although there is a growing body of exciting evidence that supports the use of A. indica as an antimicrobial, additional studies are clearly needed to determine the specific mechanisms of action, clinical efficacy, and in vivo safety of neem as a treatment for human pathogens of interest. Moreover, the various ongoing studies and the diverse properties of neem discussed herein may serve as a guide for the discovery of new antimicrobials that may exist in other herbal panaceas across the globe.

Interference of quorum sensing regulated bacterial virulence factors and biofilms by Plumbago zeylanica extract

There has been tremendous spread of antimicrobial resistance globally, mainly due to the excessive and unnecessary use of antibiotics, making the situation alarming. This has created a need for the development of alternative strategies to selectively target the bacterial pathogenicity without exerting selection pressure for the development of antimicrobial resistance. Targeting quorum sensing (QS)-mediated virulence and biofilms by nontoxic natural products is gaining importance as new control strategy to combat the virulence and biofilms of pathogenic bacteria. In this study, the crude extract of Plumbago zeylanica was fractioned in different solvents using liquid-liquid partitioning to obtain the most bioactive fraction. The inhibitory effect of the bioactive extract of P. zeylanica on QS at sub-minimum inhibitory concentrations (MICs) was studied against Chromobacterium violaceum 12472, Pseudomonas aeruginosa PAO1, and Serratia marcescens MTCC 97. Biofilm inhibition was studied using microtiter plate assay, scanning electron microscopy, and confocal laser scanning microscopy. Major phytocompounds detected were cinnamaldehyde dimethyl acetal, plumbagin, asarone, 4-chromanol, phthalic acid, palmitic acid, ergost-5-en-3-ol, stigmasterol, and β-sitosterol. The violacein production in C. violaceum 12472 was reduced by >80% in the presence of P. zeylanica hexane fraction (PZHF; 200 μg/ml). The most active PZHF inhibited QS-mediated virulence factors of P. aeruginosa PAO1 such as pyocyanin, pyoverdin, rhamnolipid production, motility, etc., significantly at sub-MICs. Similarly, PZHF showed 59 to 76% inhibition of biofilm formation of above test pathogens. The findings revealed that active fraction of P. zeylanica was effective against the QS-regulated functions and biofilms development of Gram -ve pathogenic bacteria.

Optimized microwave-assisted extraction of polyphenols and tannins from Syzygium cumini (L.) Skeels leaves through an experimental design coupled to a desirability approach

The present study consisted in optimizing the extractive method of polyphenols and total tannins of leaves of Syzygium cumini (L) Skeels assisted by microwaves to potentiate the antimicrobial activity of the dried extract of S. cumini against sensitive and resistant strains. A Box-Behnken design that consisted of 27 experimental runs coupled with a desirability function for multiple response optimization was employed to optimize the total polyphenols content and total tannins content. Antimicrobial sensitivity tests were evaluated by obtaining the minimum inhibitory concentration, minimum fungicidal concentration and minimum bactericidal concentration in 96-well petri dishes. The optimal extraction conditions were found to be 8 min of extraction, under 300 w of microwave power, using a 1:34 g/mL solid/solvent ratio and 38% of ethanol concentration as extraction solvent. The parameter with the greatest influence in the extraction was primarily the time, followed by the potency and proportion solid/solvent. This yielded a total polyphenol content of 87.37 ± 1.85 mg TAE g-1ext and a total tannin content of 79.68 ± 1.64 mg TAE g-1 ext. All tested microorganisms were sensitive to the extract, evidencing the effectiveness of the extraction method optimization.

Candida albicans Biofilm Inhibition by Ethnobotanicals and Ethnobotanically-Synthesized Gold Nanoparticles

The virulence and drug resistance of globally prevalent Candida albicans has presented complications toward its control while advances in effective antivirulence drugs remain critical. Emerging methods are now being evaluated to facilitate development of novel therapeutic approaches against this pathogen. This study focuses on the biofilm formation inhibition of ethnobotanical crude extracts and the use of nanotechnology through the ethnobotanically-synthesized gold nanoparticles to control C. albicans. Control on biofilm formation was compared using crude extracts (CEs) and biologically synthesized gold nanoparticles (CEs + AuNPs). Significantly lower biofilm formation was exhibited in thirteen (13) CEs and fourteen (14) CEs + AuNPs. Biofilm-linked genes Bcr1 and HSP90 expression were consequently downregulated. Higher biofilm inhibition activity was noted in some CEs + AuNPs compared to its counterpart CEs. This study emphasizes the biofilm inhibition activity of ethnobotanicals and the use of nanoparticles to enhance delivery of compounds, and points to its prospects for developing anti-pathogenic drugs without evolving resistance.

Antibacterial, antifungal and antioxidant activities of whole plant chemical constituents of Rumex abyssinicus

Background

Antibiotic resistance has contributed to the burden of infectious diseases both in the hospital and community setting, and represents a great threat to public health. Previous studies have revealed the role of reactive oxygen species as intermediate mediators of tissue damage, following antibiotherapies, indicating the need of associating antioxidants to these treatments. Therefore, the present work was designed to study the antibacterial, antifungal and antioxidant activities of extracts and compounds from Rumex abyssinicus Jacq. (Polygonaceae), as well as to investigate the antibacterial mechanisms of action of the most effective agents.

Methods

The plant extracts were prepared by maceration in organic solvents followed by column chromatography of the EtOAc fraction and purification of different fractions which led to the isolation and characterization of pure compounds. The antimicrobial activities of the extracts/compounds and their combinations with ciprofloxacin and fluconazole were evaluated using the broth microdilution method by determining the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC). The effects of the extracts on the bacterial cell membrane and microbial respiratory chain dehydrogenase enzyme activity were determined by spectrophotometric methods. Antioxidant activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and gallic acid equivalent antioxidant capacity (GAEAC) assays.

Results

Chrysophanol (1), physcion (2), Ergosta-6,22-diene-3,5,8-triol (3), emodin (4), 6-hydroxyemodin (citreorosein) (5), chrysophanein (6) and physcionin (7) were isolated from EtOAc fraction of R. abyssinicus and displayed different degrees of antimicrobial activities (MIC = 8–256 μg/mL). The MeOH extract and compounds 2 and 4 exhibited synergistic effects with ciprofloxacin and fluconazole. Compounds 1, 2 and the combined mixture of 6 + 7 displayed the highest antioxidant activity (GAEAC = 83.38–106.03 μg/mL).

Conclusion

R. abyssinicus is a potential source of antibacterial, antifungal and antioxidant agents. The antibacterial mechanisms of action of the MeOH extract and compound 2 are due to disruption of the cytoplasmic membrane and inhibition of the microbial respiratory chain dehydrogenase enzyme activity. To the best of our knowledge, this is the first report of test samples and ciprofloxacin / fluconazole association against MDR strains. The observed activity of the isolated compounds against bacteria and fungi including MDR strains deserves further exploration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03325-y.

Antibacterial Activity and Time-kill Assay of Terminalia catappa L. and Nigella sativa L. against Selected Human Pathogenic Bacteria

The current investigation aims to test the susceptibility of human pathogenic clinical isolates and MTCC strains to leaf and seed extracts of Terminalia catappa and Nigella sativa. Disc diffusion assay, micro dilution assay and minimum Bactericidal Concentration investigated the susceptibility of bacteria to the test extracts. The active extract was subjected to phytochemical screening, separation of the phytochemicals by Thin Layer Chromatography, bioactivity guided assay and Time- kill assay. Acetone and methanol extracts of T.catappa revealed, significant inhibition of clinical origin Staphylococcus aureus followed by Proteus vulgaris and the MTCC strains Staphylococcus aureus, Salmonella typhi, Pseudomonas aeroginosa and Bacillus subtilis. Nigella sativa inhibited the growth of clinical origin Staph.aureus and MTCC strain of Staph.aureus, Salmonella typhi and B.subtilis. Minimum inhibitory concentration for all the test bacteria was reported in the range of 5000μg/ml to 9 μg/ml in T. catappa extract. Most sensitive being the clinical isolate Staph. aureus and Proteus vulgaris. The bactericidal concentration for the test bacteria was found to be between 5000μg/ml and 625μg/ml. Phyto-chemical analysis of leaf extracts of T. catappa found to have dominated by polyphenols (Terpenoids, steroids, flavonoids, flavones, saponins and tannins) and N.sativa extracts recorded the presence of alkaloids, proteins and oils and fats. TLC profiling of the acetone extract revealed many antibacterial active bands. Bands having Retention factor 0.47 and 0.52 were active against the test bacteria. Time kill assay of the acetone extract of T. catappa were carried out for the first time. The extract exhibited dose dependent bactericidal and bacteriostatic activity against the clinical isolates.

Antimicrobial and Anti-Biofilm Activities of Citrus sinensis and Moringa oleifera Against the Pathogenic Pseudomonas aeruginosa and Staphylococcus aureus

Context The plant Moringa oleifera Lam (Moringaceae), generally termed as drumstick tree, and Citrus sinensis Linn (Rutaceae) fruit have the ability to treat multiple human infections. A biofilm is none other than a complicated microbial community whose nature is greatly resistant to antimicrobial elements. The development of biofilms in abiotic and biotic surfaces has a connection with higher levels of mortality and morbidity. Along with that, it is regarded as a vital element of bacterial pathogenicity. Aim The present study evaluated the inhibitory effect and anti-biofilm activity of Moringa oleifera (M. oleifera) and Citrus sinensis (C. sinensis) extracts against those of pathogenic Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) . Materials and methods Two plant materials were collected from the local market of Tabuk city and two human pathogenic microbial strains were used in the study: S. aureus and P. aeruginosa. Further, a series of morphological, physiological, and conventional biochemical tests were performed to identify the selected microorganisms. In addition to this, the study conducted the following tests: antibiotic sensitivity test, extended-spectrum β-lactamase (ESβL), and methicillin-resistant Staphylococcus aureus (MRSA) production, biofilm formation in 96-well microtiter plates, minimum inhibitory concentration (MIC) determination, the effect of sub-MICs of C. sinensis extract and M. oleifera extract on the viability of test bacteria, and finally, measurement of the inhibition of biofilm. Results A remarkable result of the research is that the peel extract of C. sinensisand the flesh extract of M. oleifera efficiently inhibited biofilm formation by the addition of sub-inhibitory concentrations of (1/16 x MIC - 1/2 x MIC) MRSA and ESBL, respectively. P. aeruginosa shows high resistance to piperacillin (85.0%). Similarly, the resistance of MRSA was also high (65%) against gentamycin and amikacin antibiotics. Regarding ESBL, 12 (60%) isolates showed confirmed positive and 45% of S. aureus showed MRSA activity. On observing the 12 ESβL-positive P. aeruginosa, it was found that five strains (PS1, PS4, PS6, PS8, and PS11) have formed strong biofilm, methicillin-resistant S. aureus while four strains showed strong biofilm activity (SA2, SA4, SA5, and SA8). The MIC of C. sinensis extract and M. oleifera extract against strong biofilm producers had a range of 50-2000 µg/ml concentration after overnight incubation. The study results revealed that the antibiofilm activity comparatively showed the extract of M. oleifera was better than C. sinensisagainst the mixed culture (PS1+SA8, PS6+SA2, and PS8+SA4). Hence, it is recommended to use M. oleifera as an option to monitor the development of microbial biofilms or as a model for looking for better medicines. Conclusion The presence of antimicrobial activity found in M. oleifera and C. sinensis extracts offers convincing evidence of their likely action as antimicrobial metabolites against the studied microorganism. Anti-biofilm assay findings have shown that M. oleifera and C. sinensis extracts have effectively blocked MRSA and ESBL development in the biofilm matrix.

Phytochemical conjugation as a potential semisynthetic approach toward reactive and reuse of obsolete sulfonamides against pathogenic bacteria

The emergence and reemergence of multidrug-resistant (MDR) bacteria and mycobacteria in community and hospital periphery have directly enhanced the hospitalization costs, morbidity and mortality, globally. The appearance of MDR pathogens, the currently used antibiotics, remains insufficient, and the development of potent antibacterial(s) is merely slow. Thus, the development of active antibacterials is the call of the day. The sulfonamides class of antibacterials was the most successful synthesized drug in the 19th century. Mechanically, sulfonamides were targeting bacterial folic acid biosynthesis and today, those are obsolete or clinically inactive. Nevertheless, the magic sulfonamide pharmacophore has been used continuously in several mainstream antibacterial, antidiabetic, antiviral drugs. Concomitantly, thousands of phytochemicals with antimicrobial potencies have been recorded and were commanded as alternate antibacterials toward control of MDR pathogens. However, none/very few isolated phytochemicals have gone up to the pure-drug stage due to the lack of the desired drug-likeness values and the required pharmacokinetic properties. Thus, chemical modification of parent drug remains as the versatile approach in antibacterial drug development. Improvement of clinically inactive sulfa drugs with suitable phytochemicals to develop active, low-toxic drug molecules followed by medicinal chemistry could be prudent. This review highlights such "sulfonamide-phytochemical" hybrid drug development research works for utilizing inactive sulfonamides and phytochemicals; the ingenious cost-effective and resource-saving hybrid drug concept could be a new trend in current antibacterial drug discovery to reactive the obsolete antibacterials.

Natural therapeutics for urinary tract infections-a review

Background

The recurrence of the urinary tract infections (UTI), following the antibiotic treatments suggests the pathogen’s resistance to conventional antibiotics. This calls for the exploration of an alternative therapy.

Main body

The anti-uropathogenic and bactericidal activity of many plant extracts was reported by many researchers, which involves only preliminary antibacterial studies using different basic techniques like disk diffusion, agar well diffusion, or minimum inhibitory concentration (MIC) of the crude plant extracts, but reports on the specific action of the phytoconstituents against uropathogens are limited. Vaccinium macrocarpon Aiton (cranberry) is the best-studied home remedy for UTI. Some evidences suggest that proanthocyanins present in cranberry, prevent bacteria from adhering to the walls of the urinary tract, subsequently blocking the further steps of uropathogenesis. Probiotics such as Lactobacillus and Bifidobacterium are beneficial microorganisms that may act by the competitive exclusion principle to defend against infections in the urogenital tracts. Reports on potential vaccine agents and antibodies targeting the different toxins and effecter proteins are still obscure except uropathogenic E. coli.

Conclusion

This review highlights some of the medicinal herbs used by aborigines to prevent or treat acute or chronic urinary tract infections, botanicals with established urobactericidal activity, clinical trials undertaken to compare the efficacy of cranberry products in UTI prevention, and other natural therapeutics reported for UTI.

Antibacterial Mechanism of Vanillic Acid on Physiological, Morphological, and Biofilm Properties of Carbapenem-Resistant Enterobacter hormaechei

ABSTRACT

Many studies have evaluated the antimicrobial activity of natural products against various microorganisms, but to our knowledge there have been no studies of the possible use of natural products for their antimicrobial activity against Enterobacter hormaechei. In this study, we investigated vanillic acid (VA) for its antimicrobial activities and its modes of action against carbapenem-resistant E. hormaechei (CREH). The MIC of VA against CREH was determined by the agar diffusion method. The antibacterial action of VA against CREH was elucidated by measuring variations in intracellular ATP concentration, intracellular pH, membrane potential, and cell morphology. Moreover, the efficacy of VA against biofilm formation and VA damage to CREH cells embedded in biofilms were further explored. Our results show that VA was effective against CREH with a MIC of 0.8 mg/mL. VA could rupture the cell membrane integrity of CREH, as measured by a decrease of intracellular ATP, pH, and membrane potential, along with distinctive alternations in cell morphology. In addition, VA exerted a remarkable inhibitory effect on the biofilm formation of CREH and also killed CREH cells within biofilms. These findings show that VA has a potent antibacterial and antibiofilm activity against CREH and, hence, has the potential to be used clinically as a novel candidate agent to treat CREH infections and in the food industry as a food preservative and surface disinfectant.

HIGHLIGHTS

Antibacterial activity of Syzygium aromaticum (clove) against uropathogens producing ESBL, MBL, and AmpC beta-lactamase: Are we close to getting a new antibacterial agent?

Introduction

The present study was done to access the antibacterial activity of clove (Syzygium aromaticum) against extended-spectrum beta-lactamase (ESBL), metallo-beta-lactamase (MBL), and AmpC beta-lactamase-producing gram-negative bacteria causing urinary tract infection.

Methods

A total of 221 gram-negative uropathogens were isolated and screened for beta-lactamase (ESBL, MBL, and AmpC) production and further tested against ethanolic extract of clove (S. aromaticum) for its antibacterial activity.

Results

Clove was effective against all gram-negative isolates but the best antibacterial activity was shown against Proteus species with 19 mm zone of inhibition, 0.39 mg/ml minimum inhibitory concentration (MIC) and 0.19 mg/ml minimum bactericidal concentration (MBC).

Conclusions

Clove extract showed different antibacterial potential against all gram-negative uropathogens. Clove activity for particular strain was found to be similar between isolates producing beta-lactamase and non beta-lactamase.

Evaluation of antimicrobial activity of chondrillasterol isolated from Vernonia adoensis (Asteraceae)

BACKGROUND

Bacteria have developed resistance to most of the current antibiotics. There is evidence suggesting that plant-derived compounds have a potential for interacting with biological processes. One of the plants commonly used in African ethnomedicine is Vernonia adoensis from the Asteraceae family. The leaves of the plant have been reported to have antimicrobial activity. Hence, the aim of this study was to isolate the bioactive compounds from the leaf extract and evaluate their antibacterial activity on Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa. In addition, the effect of the isolated compound on biofilms of P. aeruginosa was determined.

METHODS

Isolation of phytochemicals from the leaves of V. adoensis was done using column chromatography. Preparative TLC was used to further isolate mixed compounds in the fractions. Nuclear magnetic resonance spectroscopy and mass spectrometry was used to identify the isolated pure compounds. The broth microdilution assay was carried out to evaluate the antibacterial activity of the isolated compound on P. aeruginosa, S. aureus and K. pneumoniae. Crystal violet staining technique was used to evaluate the effect of the isolated compound on biofilms of P. aeruginosa.

RESULTS

The compound isolated from V. adoensis was identified as chondrillasterol. Chondrillasterol exhibited 25, 38 and 65% inhibition of growth on S. aureus, K. pneumoniae and P. aeruginosa respectively. At 1.6 μg/mL chondrillasterol completely disrupted mature biofilm of P. aeruginosa while at 100 μg/mL the compound completely inhibited formation of biofilms of the bacteria.

CONCLUSION

Chondrillasterol isolated from V. adoensis has antibacterial properties against S. aureus, K. pneumoniae and P. aeruginosa. The compound also has biofilm inhibition and disruption activity against P. aeruginosa biofilms. Thus, the active phytochemical could be a useful template for the development of new antimicrobial agents with both antibacterial and antibiofilm activity.

Review on antibacterial activity of Himalayan medicinal plants traditionally used to treat pneumonia and tuberculosis

Objectives

The main objective of this review was to collect scattered literature on ethnomedicinal plants used to treat pneumonia and tuberculosis in the Himalayan region and their in-vitro validation against bacterial pathogens.

Key findings

Current review contains information on ethnomedicines of total 137 plants from Himalaya region. Out of these, 59 plants have been studied in vitro against bacteria while seven plants extracts have been checked for their toxicological effects. The most commonly used plant families for pneumonia and tuberculosis therapy in the study region were Asteraceae, Bignoniaceae and Fabaceae (seven plants in each); of these, Curcuma longa L., Punica granatum L. and Justicia adhatoda L. carried the most inhibiting potential against Staphylococcus aureus and Streptococcus pneumoniae while that of Acalypha indica L. against Mycobacterium tuberculosis. Different compounds such as ascorbic acid, curcumin, vasicine, piperine, quercetin, myricetin and gallic acid being reportedly isolated from these plants possess antibacterial potential.

Summary

Himalayan region has variety of ethnomedicinal plants used against pneumonia and tuberculosis; however, studies on in-vivo activity, toxicology and mechanism of action are very limited. Hence, detailed investigation on these aspects needs to be carried out for the development of novel antibacterial drugs from the studied plant species.

Prevalence of Dermatophytosis and Antifungal Activity of Ethanolic Crude Leaf Extract of Tetradenia riparia against Dermatophytes Isolated from Patients Attending Kampala International University Teaching Hospital, Uganda

Dermatophyte infections are a global health problem but neglected in Uganda. This work aimed at determining prevalence of dermatophytosis and antifungal activity of ethanolic crude leaf extract of Tetradenia riparia against dermatophytes isolated from patients attending Kampala International University Teaching Hospital (KIU-TH), Uganda. A total of 100 samples of skin and nail scrapings were collected and processed using standard microscopy (KOH) and cultural methods. T. riparia leaves were collected and processed with 95% ethanol using standard extraction method. The crude leaves ethanolic extract was tested against three dermatophytes: Trichophyton tonsurans, T. mentagrophyte, and Microsporum audouinii using modified agar well diffusion method. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of the ethanolic leaves crude extract were also determined using broth tube dilution and culture, respectively. Out of 100 samples collected, 49 (49%, 95%CI: 0.3930-0.5876) were found positive for microscopy. The prevalence of dermatophytosis was significantly (p=0.001) associated with age groups of participants with higher infection among those aged 11-20 and 21-30 years with 75.0% each. Out of the 49 that were positive by microscopy, 28 (57.15%, 95% CI: 0.1987-0.3739) were positive by culture. Thirty-one (31) fungal isolates were obtained which included both dermatophyte and non-dermatophyte fungi. T. verrucosum had highest distribution 6 (19.35%) among dermatophytes species while Aspergillus spp. were found to have highest distribution 7 (22.58%) among non-dermatophyte species. The result of the antidermatophytic test showed that T. riparia ethanolic crude leaves extract had activity against tested dermatophytes at 1 g/ml. MIC and MFC of the crude extract of T. riparia against tested dermatophytes ranged from 62.5 to 250 mg/ml and 125 to 500 mg/ml, respectively. The findings of this study reported the presence of dermatophytes causing dermatophytosis among patients attending KIU-TH. The results of the current study showed that T. riparia leaves ethanolic crude extract has antidermatophytic activity against tested dermatophytes.

In vitro Antioxidant, Antibacterial Activities and HPLC-TOF/MS Analysis of Anvillea radiata (Asteraceae) Extracts

Background:

Algeria has a particular geographical position with a wide band of very varied vegetation including the aromatic and medicinal plants. These plants are able to produce much diversified natural compounds, which can be very useful health care and treatment of diseases.

Objective:

This study was carried out to evaluate the antioxidant capacity and antibacterial activity of Anvillea radiata (Asteraceae) extracts, one of the medicinal plants used as food and in folk medicine in Algeria.

Methods:

The extraction was carried on the aerial part by methanol and water to give Met.E and Aq.E. The ABTS and DPPH free radicals-scavenging tests are used to evaluate the antioxidant activity of extracts. Moreover, the antibacterial activity was evaluated using disc diffusion method. Finally, the extracts were subject to the phytochemical analysis using the HPLC-TOF/MS equipment.

Results:

The Met.E showed the highest amount of total phenolic and flavonoids content (266.12 µg EAG/mg E and 50.83 µg EQ/mg E, respectively). The results of the antioxidant activity revealed that the Met.E showed a good scavenging activity against ABTS and DPPH free radical with EC50=0.067 mg/ml and EC50=0.33 mg/ml, respectively. Moreover, the A. radiata extracts present a highest antibacterial activity against M. luteus NRRL B-4375, B. subtilis NRRL NRS-744 and S. aureus ATCC 25923, with inhibition zone ranging from 18 to 23 mm to Met.E and 12-18 mm to the Aq.E. In addition, the Met.E of A. radiata showed a better MIC against S. aureus, M. luteus and B. subtilis (MIC= 6.25, 25 and 25 µg/ml, respectively). The HPLC-TOF/MS analysis of Met.E reveals the presence of two major compounds, rutin and fumaric acid, when Aq.E contains the syringic acid as a major compound.

Conclusion:

The data of our study reported that the Met.E extract of A. radiata had a considerable antioxidant capacity and antibacterial effect, which may be due to their richness by phenolic compounds such as rutin and fumaric acid.

Three new diphenyl ether derivatives from the fermentation products of an endophytic fungus Phomopsis fukushii

Three new diphenyl ethers (1-3), together with four known isopentylated diphenyl ethers derivatives (4-7), were isolated from the fermentation products of an endophytic fungus Phomopsis fukushii. Their structures were elucidated by spectroscopic methods, including extensive 1D and 2D NMR techniques. Compounds 1-3 were evaluated for their anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) activity. The results revealed that compounds 1 and 2 showed strong inhibitions with inhibition zone diameters (IZD) of 20.2 ± 2.5 mm and 17.9 ± 2.2 mm, respectively. Compound 3 also showed good inhibition with IZD 15.2 ± 1.8 mm. The IZD data of compound 1 is close to that of positive control with IZD 21.9 ± 2.1 mm.

Insights of antidiabetic, anti-inflammatory and hepatoprotective properties of antimicrobial secondary metabolites of corm extract from Caladium x hortulanum

Medicinal plants have therapeutic potential and are used worldwide to treat various diseases. In this study, the corm of Caladium x hortulanum was extracted with various solvents and implied the availability of phytochemicals such as flavonoids, alkaloids, tannins, steroids, phenols, glycosides, saponins and terpenoids. The solvent extracts of the corm showed antibacterial and antifungal activity with the growth inhibition zone ranged 0-24 mm. The isolation of phytochemicals was carried out using gel column chromatography, Thin Layer Chromatography followed by High Performance Liquid Chromatography. Gas Chromatography and Mass Spectrophotometry analysis was used to determine the phytochemicals. The corm extract showed potent antidiabetic activity on Hep G2 cell lines and CCl4 induced toxicity was elucidated. This possessed antiinflammatory property on murine monocyclic macrophage cell line RAW 264.7 showed 45.85 ± 1.8% inhibition of cyclooxygenase activity. The corm extract showed hepatoprotective activity. The CCl4 incorporated Hep G2 cells showed 19.629 ± 1.5% viability, whereas viability increased as 78.82 ± 1.9% at 100 µg/ml of extract.

Evaluation of the antiviral activities of Bacharis dracunculifolia and quercetin on Equid herpesvirus 1 in a murine model

Equid herpesvirus 1 (EHV-1) is a pathogen of high economic importance in equine breeding operations around the world. EHV-1 infection causes respiratory, neurologic and reproductive disease. The absence of an efficient therapy has caught the attention of the scientific community and the therapeutic activities of natural products with its antivirals effects might be effective for the disease's treatment. Herein it was evaluated the prophylactic and therapeutic potential of quercetin and ethanolic extracts of Bacharis dracunculifolia formulations compared to Penciclovir® in an in vivo EHV-1 infection model. Six to seven-week-old female C57BL/6 mice were randomly organized into fifteen groups with six animals each. Ex-1 represents the treatment post-challenge groups to assess morbidity, mortality and weight variation. Ex-2 represents the animals that received treatment for 5 days post-challenge for lesion evaluation. In Ex-3 animals were treated prior to viral challenge to assess morbidity, mortality and weight variation. All mice in the treatment groups were challenged by intranasal inoculation of 3.0 × 10⁵ TCID₅₀ EHV-1. The quercetin and B. dracunculifolia treatment decreased morbimortality in post-challenge treatment (Ex-1) and EHV-1 related lesions (Ex-2). Treatment prior to viral challenge (Ex-3) did not show any significant results. Based on the results of the present study, both tested formulations are promising antiviral agents for the treatment of EHV-1 infection.

Interspecies Anticancer and Antimicrobial Activities of Genus Solanum and Estimation of Rutin by Validated UPLC-PDA Method

Solanaceae is one of the highly diverse plant families of which Solanum is the largest genera (1700 species) containing several pharmacological properties like anticancer and antimicrobial. This motivated us to explore the anticancer (against HepG2, HEK-293, and MCF-7 cells) and antimicrobial (against S. aureus, E. coli, P. aeruginosa, and C. albicans) properties of S. schimperianum, S. villosum, S. coagulans, S. glabratum, S. incanum, and S. nigrum along with rutin estimation by UPLC-PDA method. Of the studied Solanum extracts, S. nigrum exhibited significant cytotoxic property against HepG2 (IC50: 20.4 μg/mL) and MCF-7 (IC50: 30.1 μg/mL); S. coagulans showed toxicity against HepG2 (IC50: 28.4 μg/mL) and HEK-293 cells (IC50: 25.7 μg/mL) compared to 5-Fluorouracil (standard). Compared to these, extracts of S. coagulans and S. glabratum exhibited relatively high antimicrobial potency (MIC: 0.4-1.6 mg/mL). Nonetheless, all Solanum extracts significantly reduced the biofilm against PAO1-strain. Rutin was detected in all extracts with the highest content (53.79 μg/mg) in S. coagulans that supported its strong antimicrobial and anticancer properties. Molecular docking analysis showing strong binding of rutin with human DNA and proteins (DNA Topoisomerase IIα and E. coli DNA gyrase B) supported the anticancer and antimicrobial activities of Solanum species.

Broad‐spectrum inhibitory effect of green synthesised silver nanoparticles from Withania somnifera (L.) on microbial growth, biofilm and respiration: a putative mechanistic approach

Multi‐drug resistance in pathogenic bacteria has created immense clinical problem globally. To address these, there is need to develop new therapeutic strategies to combat bacterial infections. Silver nanoparticles (AgNPs) might prove to be next generation nano‐antibiotics. However, improved efficacy and broad‐spectrum activity is still needed to be evaluated and understood. The authors have synthesised AgNPs from Withania somnifera (WS) by green process and characterised. The effect of WS‐AgNPs on growth kinetics, biofilm inhibition as well as eradication of preformed biofilms on both gram‐positive and gram‐negative pathogenic bacteria was evaluated. The authors have demonstrated the inhibitory effect on bacterial respiration and disruption of membrane permeability and integrity. It was found that WS‐AgNPs inhibited growth of pathogenic bacteria even at 16 µg/ml. At sub‐minimum inhibitory concentration concentration, there was approximately 50% inhibition in biofilm formation which was further validated by light and electron microscopy. WS‐AgNPs also eradicated the performed biofilms by varying levels at elevated concentration. The bacterial respiration was also significantly inhibited. Interaction of WS‐AgNPs with test pathogen caused the disruption of cell membrane leading to leakage of cellular content. The production of intracellular reactive oxygen species reveals that WS‐AgNPs exerted oxidative stress inside bacterial cell causing microbial growth inhibition and disrupting cellular functions.

Comparative anticancer and antimicrobial activity of aerial parts of Acacia salicina, Acacia laeta, Acacia hamulosa and Acacia tortilis grown in Saudi Arabia

The standardized ethanol extract (EE) of aerial parts of four Acacia species [A. salicina (ASEE), A. laeta (ALEE), A. hamulosa (AHEE), and A. tortilis (ATEE)] were examined in order to compare their cytotoxic and antimicrobial activities. All the extracts were standardized by UPLC- PDA method using rutin as standard compound. The extracts ALEE, AHEE and ATEE were found to contain rutin along with several other phytoconstituents while rutin was absent in ASEE. All the extracts showed varying level of antimicrobial activity with zone of inhibition ranged from 11 to 21 mm against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. The ALEE and ATEE showed relatively high antimicrobial potency (MIC = 0.2 to 1.6 mg mL⁻¹) in comparison to other extracts. All the extracts were found to reduce the biofilm of P. aeruginosa PAO1 strain significantly in comparison to the untreated control. The cytotoxic property of ASEE, ALEE, AHEE, ATEE were evaluated against HepG2 (Liver), HEK-293 (Kidney), MCF-7 (Breast) and MDA-MB 231 (Breast) cancer cells. Of these, ALEE, AHEE and ATEE exhibited moderate cytotoxic property against human liver carcinoma cells (HepG2; IC50 = 46.2, 39.2 and 42.3 μg mL⁻¹, respectively) and breast cancer cell lines (MCF-7; IC50 = 57.2, 55.3 and 65.7 μg mL⁻¹, respectively). The ATEE and ALEE showed moderate cytotoxicity against HEK-293 (kidney) cells with IC50 = 49.1 and 53.5 μg mL⁻¹, respectively. Since, Acacia species (A. laeta and A. hamulosa) contains numerous polyphenols which might prove to be highly cytotoxic and antimicrobial agents, we suggest that these species can be further subjected to the isolation of more cytotoxic and antimicrobial compounds.

TLC Bioautography-guided Isolation and Antimicrobial, Antifungal Effects of 12 Alkaloids from Hylomecon japonica Roots§

Hylomecon japonica (Thunb.) Prantl. is a Chinese medicinal plant whose active components and their antimicrobial mechanism was studied by TLC bioautography-guided isolation and identification of 12 alkaloids and their antimicrobial activities evaluated using the standard broth microdilution method. The benzophenanthridine isoquinoline alkaloids showed the strongest inhibitory activity against Gram-positive bacteria. Analysis of conductivity changes and observation of TEM images revealed that the antimicrobial mechanism involved cell integrity damage and cell division arrest.

Inhibition of pro-inflammatory enzymes by medicinal plants from the Argentinean highlands (Puna)

ETHNOPHARMACOLOGICAL RELEVANCE

Human groups in the Argentinean Andes highlands (Puna) selected native plants as anti-inflammatory agents. The indications of use are mainly to relieve pain, as infusions, ethanolic extracts or plasters.

AIM OF THE STUDY

The objective of the study was to assess the effect of hydroalcoholic extracts from native highland plants as anti-inflammatory agents according to the traditional indications of use. The chemical profile of the three most active species was analyzed by HPLC-ESI-MS to get an insight into the constituents and the effects observed according to the ethnopharmacological information.

MATERIALS AND METHODS

Hydroalcoholic extracts from 13 Argentinean Puna plants used as anti-inflammatory were evaluated as inhibitors of the pro-inflammatory enzymes phospholipase A₂ (sPLA₂), lipoxygenase (LOX), hyaluronidase, and for their capacity to stabilize red blood cells membrane. In addition, the extracts were evaluated to determine their reducing power, iron chelating capacity and ABTS^•+ radical scavenging effect. The chemical profiles of the most active species were analyzed by HPLC-ESI-MS.

RESULTS

Among the species investigated, Ephedra multiflora was the most active as LOX inhibitor (IC₅₀:132µg/mL), by reducing the non-heme iron group and by scavenging radicals. The IC₅₀ values of the reference compounds caffeic acid and naproxen were 57.0 and 14.0µg/mL, respectively. Parastrephia lucida showed the highest sPLA₂ inhibitory effect (63% of inhibition at 200µg/mL). Under the same experimental conditions, the IC₅₀ of the reference compound acetylsalicylic acid was 65±1µg/mL. Tessaria absinthioides exhibited the best inhibition towards hyaluronidase with an IC₅₀ of 93.2±4.3µg/mL. Under the same experimental conditions, the reference compounds quercetin and indomethacin presented IC₅₀ values of 340.0±17.0 and 502.0±10.0µg/mL, respectively. Among the most active species, 13 compounds were tentatively identified by HPLC-ESI-MS in E. multiflora and P. lucida, and 12 compounds in T. absinthioides. The constituents included caffeoyl- and feruloylquinic acid derivatives, flavonoids, simple phenolics and sesquiterpene glycosides.

CONCLUSIONS

Six out of the 13 species investigated showed a moderate to strong effect towards the enzyme sPLA₂ (>40% inhibition at 200µg/mL) while three species presented a strong activity against LOX with IC₅₀<250µg/mL and three were very active against hyaluronidase. Most of the crude drug extracts were able to stabilize the red blood cells membrane, preventing their lysis. The compounds identified in the extracts explain, at least in part, the activity found in the samples. The effect observed for the most active species supports their traditional use as anti-inflammatory agents. However, more studies should be undertaken to disclose the potential of the Puna plants as anti-inflammatory crude drugs.

Burdock (Arctium lappa) Leaf Extracts Increase the In Vitro Antimicrobial Efficacy of Common Antibiotics on Gram-positive and Gram-negative Bacteria

This work aimed to study the potential effects of four Arctii folium extracts, 5 mg gallic [GAE] acid equivalents per 1 mL sample, on six antibiotics (Ampicillin/AM, Tetracycline/TE, Ciprofloxacin/CIP, Sulfamethoxazole-Trimethoprim/SXT, Chloramphenicol/C and Gentamicin/CN) tested on four Gram-positive (Staphylococcus aureus ATCC 6538, Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, and Staphylococcus epidermidis ATCC 12228) and five Gram-negative (Proteus mirabilis ATCC 29245, Escherichia coli ATCC 35218, E. coli ATCC 11229, E. coli ATCC 8739, and Bacillus cereus ATCC 11778) bacteria. Arctii folium extracts were the whole ethanol extract/W and subsequent ethyl acetate/EA, aqueous/AQ, and chloroform/CHL fractions. Chemical qualitative analysis (HPTLC method) emphasized five main polyphenol compounds in Arctii folium polar extracts: chlorogenic acid (Rf≈0.52/0.55) and its isomer, 1,5-di-O-caffeoylquinic acid (Rf≈0.90/0.92), plus cynarin (Rf≈0.77), hyperoside (Rf≈0.68/0.64) and isoquercitrin (Rf≈0.69/0.71). Microbiological screening indicated Arctii folium polar extracts (AQ and W) efficacy on S. epidermidis ATCC 12228; the MIC values were in the range of common antibiotics, being 32 and 128 μg GAE per mL sample respectively. The unpredictable effects (stimulatory or inhibitory) of Arctii folium extracts in combination with typical antibiotics as well as a potential use of the whole ethanol extract/W for restoring the antimicrobial potency of susceptible antibiotics have also been evidenced.

Leaf Extracts of Mangifera indica L. Inhibit Quorum Sensing - Regulated Production of Virulence Factors and Biofilm in Test Bacteria

Quorum sensing (QS) is a global gene regulatory mechanism in bacteria for various traits including virulence factors. Disabling QS system with anti-infective agent is considered as a potential strategy to prevent bacterial infection. Mangifera indica L. (mango) has been shown to possess various biological activities including anti-QS. This study investigates the efficacy of leaf extracts on QS-regulated virulence factors and biofilm formation in Gram negative pathogens. Mango leaf (ML) extract was tested for QS inhibition and QS-regulated virulence factors using various indicator strains. It was further correlated with the biofilm inhibition and confirmed by electron microscopy. Phytochemical analysis was carried out using ultra performance liquid chromatography (UPLC) and gas chromatography–mass spectrometry (GC-MS) analysis. In vitro evaluation of anti-QS activity of ML extracts against Chromobacterium violaceum revealed promising dose-dependent interference in violacein production, by methanol extract. QS inhibitory activity is also demonstrated by reduction in elastase (76%), total protease (56%), pyocyanin (89%), chitinase (55%), exopolysaccharide production (58%) and swarming motility (74%) in Pseudomonas aeruginosa PAO1 at 800 μg/ml concentration. Biofilm formation by P. aeruginosa PAO1 and Aeromonas hydrophila WAF38 was reduced considerably (36–82%) over control. The inhibition of biofilm was also observed by scanning electron microscopy. Moreover, ML extracts significantly reduced mortality of Caenorhabditis elegans pre-infected with PAO1 at the tested concentration. Phytochemical analysis of active extracts revealed very high content of phenolics in methanol extract and a total of 14 compounds were detected by GC-MS and UPLC. These findings suggest that phytochemicals from the ML could provide bioactive anti-infective and needs further investigation to isolate and uncover their therapeutic efficacy.

INVESTIGATION OF ANTIHEMOLYTIC, XANTHINE OXIDASE INHIBITION, ANTIOXIDANT AND ANTIMICROBIAL PROPERTIES OF SALVIA VERBENACA L. AERIAL PART EXTRACTS

BACKGROUND

In this study, Salvia verbenaca L. aerial part extracts (SVEs): were screened for their antihemolytic, xanthine oxidase (XO) inhibition, antioxidant and antimicrobial activities.

MATERIAL AND METHODS

To investigate SVEs antihemolytic activity, the 2,2,-azobis (2-amidinopropane) dihydrochloride (AAPH) was used to induce erythrocyte oxidative hemolysis. In XO inhibition test, xanthine was used as substrate and cytochrome c for generating superoxide anions. The antioxidant activity of SVEs was examined by means of reducing power, DPPH free radical scavenging and iron chelating assays. In addition, SVEs were tested for their antimicrobial effects by evaluating antibacterial and antifungal activities.

RESULTS

Ethyl acetate extract (EAE) contains the highest amount of total polyphenols and flavonoids (661.78 ± 4.00 mg GAE / g E) and (28.81 ± 0.38 mg QE / g E) respectively. In antihemolytic test EAE was the most active extract with an HT₅₀ value of 165 min. SVEs gave significant inhibitory effects on XO, especially the chloroform extract (ChE) with IC₅₀ value of 0.0088 ± 0.000 mg/ml. EAE was the most active extract in reducing power essay (EC₅₀: 0.0047 ± 0.000 mg/ml) and in DPPH radical scavenging essay (IC₅₀: 0.0086 ± 0.000 mg/ml). Finally, the EAE has inhibited the growth of nine bacterial strains with inhibition zone diameters of (12 to 16 mm), but no activities have found against fungal strains.

CONCLUSION

S. verbenaca could be considered as a potential source of natural antihemolytic, enzyme modulator, antioxidant and antibacterial agents.

Thin Layer Chromatography-Bioautography and Gas Chromatography-Mass Spectrometry of Antimicrobial Leaf Extracts from Philippine Piper betle L. against Multidrug-Resistant Bacteria

This study isolated and identified the antimicrobial compounds of Philippine Piper betle L. leaf ethanol extracts by thin layer chromatography- (TLC-) bioautography and gas chromatography-mass spectrometry (GC-MS). Initially, TLC separation of the leaf ethanol extracts provided a maximum of eight compounds with R_f values of 0.92, 0.86, 0.76, 0.53, 0.40, 0.25, 0.13, and 0.013, best visualized when inspected under UV 366 nm. Agar-overlay bioautography of the isolated compounds demonstrated two spots with R_f values of 0.86 and 0.13 showing inhibitory activities against two Gram-positive multidrug-resistant (MDR) bacteria, namely, methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus. The compound with an R_f value of 0.86 also possessed inhibitory activity against Gram-negative MDR bacteria, namely, carbapenem-resistant Enterobacteriaceae-Klebsiella pneumoniae and metallo-β-lactamase-producing Acinetobacter baumannii. GC-MS was performed to identify the semivolatile and volatile compounds present in the leaf ethanol extracts. Six compounds were identified, four of which are new compounds that have not been mentioned in the medical literature. The chemical compounds isolated include ethyl diazoacetate, tris(trifluoromethyl)phosphine, heptafluorobutyrate, 3-fluoro-2-propynenitrite, 4-(2-propenyl)phenol, and eugenol. The results of this study could lead to the development of novel therapeutic agents capable of dealing with specific diseases that either have weakened reaction or are currently not responsive to existing drugs.

New Perspectives on the Use of Phytochemicals as an Emergent Strategy to Control Bacterial Infections Including Biofilms

The majority of current infectious diseases are almost untreatable by conventional antibiotic therapy given the advent of multidrug-resistant bacteria. The degree of severity and the persistence of infections are worsened when microorganisms form biofilms. Therefore, efforts are being applied to develop new drugs not as vulnerable as the current ones to bacterial resistance mechanisms, and also able to target bacteria in biofilms. Natural products, especially those obtained from plants, have proven to be outstanding compounds with unique properties, making them perfect candidates for these much-needed therapeutics. This review presents the current knowledge on the potentialities of plant products as antibiotic adjuvants to restore the therapeutic activity of drugs. Further, the difficulties associated with the use of the existing antibiotics in the treatment of biofilm-related infections are described. To counteract the biofilm resistance problems, innovative strategies are suggested based on literature data. Among the proposed strategies, the use of phytochemicals to inhibit or eradicate biofilms is highlighted. An overview on the use of phytochemicals to interfere with bacterial quorum sensing (QS) signaling pathways and underlying phenotypes is provided. The use of phytochemicals as chelating agents and efflux pump inhibitors is also reviewed.

Large Scale Screening of Ethnomedicinal Plants for Identification of Potential Antibacterial Compounds

The global burden of bacterial infections is very high and has been exacerbated by increasing resistance to multiple antibiotics. Antibiotic resistance leads to failed treatment of infections, which can ultimately lead to death. To overcome antibiotic resistance, it is necessary to identify new antibacterial agents. In this study, a total of 662 plant extracts (diverse parts) from 222 plant species (82 families, 177 genera) were screened for antibacterial activity using the agar cup plate method. The aqueous and methanolic extracts were prepared from diverse plant parts and screened against eight bacterial (two Gram-positive and six Gram-negative) species, most of which are involved in common infections with multiple antibiotic resistance. The methanolic extracts of several plants were shown to have zones of inhibition ≥ 12 mm against both Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration was calculated only with methanolic extracts of selected plants, those showed zone of inhibition ≥ 12 mm against both Gram-positive and Gram-negative bacteria. Several extracts had minimum inhibitory concentration ≤ 1 mg/mL. Specifically Adhatoda vasica, Ageratum conyzoides, Alangium salvifolium, Alpinia galanga, Andrographis paniculata, Anogeissus latifolia, Annona squamosa, A. reticulate, Azadirachta indica, Buchanania lanzan, Cassia fistula, Celastrus paniculatus, Centella asiatica, Clausena excavate, Cleome viscosa, Cleistanthus collinus, Clerodendrum indicum, Croton roxburghii, Diospyros melanoxylon, Eleutherine bulbosa, Erycibe paniculata, Eryngium foetidum, Garcinia cowa, Helicteres isora, Hemidesmus indicus, Holarrhena antidysenterica, Lannea coromandelica, Millettia extensa, Mimusops elengi, Nyctanthes arbor-tristis, Oroxylum indicum, Paederia foetida, Pterospermum acerifolium, Punica granatum, Semecarpus anacardium, Spondias pinnata, Terminalia alata and Vitex negundo were shown to have significant antimicrobial activity. The species listed here were shown to have anti-infective activity against both Gram-positive and Gram-negative bacteria. These results may serve as a guide for selecting plant species that could yield the highest probability of finding promising compounds responsible for the antibacterial activities against a broad spectrum of bacterial species. Further investigation of the phytochemicals from these plants will help to identify the lead compounds for drug discovery.

Inhibitory effect and enzymatic analysis of E-cinnamaldehyde against sclerotinia carrot rot

This study was conducted to determine the inhibitory effect of E-cinnamaldehyde (EC) against causal agent of storage carrot rot, Sclerotinia sclerotiorum, under in vivo and in vitro conditions. Based on the results, EC was able to completely inhibit mycelial growth of three isolates (P>0.05) in both volatile and contact phases after 6days at the concentrations 200μl and 1μl/ml, respectively. In addition, EC at concentrations 1 and 10μl/ml completely inhibited carpogenic germination of three isolates. The results of in vivo trials showed that EC at the concentration of 10μl/ml was able to control the disease caused by isolates 1 and 3. However the disease caused by isolate 2 was inhibited with the concentration of 20μl/ml. In enzyme analyses, the activity of polyphenoloxidase and peroxidase did not change in the inoculated carrots after application of EC. Furthermore, the level of phenylalanine ammonia lyase decreased. These results indicated that EC does not have any potential to be considered as resistance inducers against sclerotinia carrot rot.

Epilobi Hirsuti Herba Extracts Influence the In Vitro Activity of Common Antibiotics on Standard Bacteria

Epilobium genus has been confirmed as an effective source of natural antimicrobials. However, the influence of Epilobi hirsuti herba derived products on usual antibiotics activity has not been studied. In this study, several standardized Epilobi hirsuti herba extracts (EHE) were evaluated in order to asses their potential effects on usual antibiotics tested on standard Gram-positive and Gram-negative bacterial strains in vitro. The results emphasized that the bacterial strains ranged from sensitive (MIC values between 50–200 μg GAE mL-1) (S. epidermidis ATCC 12228) to very resistant (E. coli strains), E. faecalis ATCC 29212 being practically immune to EHE. In terms of synergistic interaction, Tetracycline and Ampicillin combinations lead to the most important stimulatory effects, the diameters of the inhibition zone being even 60% bigger compared to the antibiotic alone. Synergistic effects between myricetin(galloyl) derivates and Tetracycline were also revealed on P. aeruginosa and E. coli strains. Together, it clearly demonstrated not only EHE’s own antimicrobial properties, but also their capacity to influence the antimicrobial potency of some common antibiotics. These results could be useful for the area of herbal medicines and as potential candidates in managing microbial resistance, but also for physicians and pharmacists using combined antibacterial therapy.

Synergistic photothermal antimicrobial therapy using graphene oxide/polymer composite layer-by-layer thin films

Simple and highly-efficient synergistic antimicrobial coatings based on graphene oxide, which could be coated on any substrate irrespective of shape.