Reproducibility challenges in the search for antibacterial compounds from nature

Masota, Nelson E.; Vogg, Gerd; Ohlsen, Knut; Holzgrabe, Ulrike

doi:10.1371/journal.pone.0255437

Cited by 11 publications

(8 citation statements)

References 49 publications

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“…According to the CLSI and EUCAST guidelines, disk diffusion assays are considered the gold standard for evaluating antimicrobial activity. However, in the case of natural extracts, there is no adequate method in all cases, so the decision must consider, among other aspects, the extract’s polarity and complexity, the available equipment, and the possibility of automation [ 233 ]. The emergent methodologies to assess the antimicrobial activity of natural extracts include isothermal microcalorimetry (IMC) and mass spectrometry.…”

Section: Antimicrobial Activitymentioning

confidence: 99%

Evaluation of Biological Activity of Natural Compounds: Current Trends and Methods

et al. 2022

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Natural compounds have diverse structures and are present in different forms of life. Metabolites such as tannins, anthocyanins, and alkaloids, among others, serve as a defense mechanism in live organisms and are undoubtedly compounds of interest for the food, cosmetic, and pharmaceutical industries. Plants, bacteria, and insects represent sources of biomolecules with diverse activities, which are in many cases poorly studied. To use these molecules for different applications, it is essential to know their structure, concentrations, and biological activity potential. In vitro techniques that evaluate the biological activity of the molecules of interest have been developed since the 1950s. Currently, different methodologies have emerged to overcome some of the limitations of these traditional techniques, mainly via reductions in time and costs. These emerging technologies continue to appear due to the urgent need to expand the analysis capacity of a growing number of reported biomolecules. This review presents an updated summary of the conventional and relevant methods to evaluate the natural compounds’ biological activity in vitro.

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Section: Antimicrobial Activitymentioning

confidence: 99%

Evaluation of Biological Activity of Natural Compounds: Current Trends and Methods

et al. 2022

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“…This is mostly due to the complexity of a majority of crude plant mixtures, posing difficulty in the hunt for compounds exhibiting the activities of interest. The choice of acetone as an extractant was guided by previously reported antibacterial activities of Paeonia broteoli leaf extracts obtained from multiple solvents with varying polarities [ 17 , 38 ]. Other findings have shown the type and molecular weight of galloylglucoses recovered during extraction to be highly dependent on the nature of the extractant used.…”

Section: Discussionmentioning

confidence: 99%

“…Our previous efforts in the search for antibacterial compounds from numerous plants revealed antibacterial activity of crude acetone leaf extract of P. officinalis against E. coli and K. pneumoniae [ 17 ]. Here, we report the isolation, purification, and characterization of four galloylglucoses from the leaves of P. officinalis and their antibacterial activities against 2 reference and 13 multidrug-resistant (MDR) strains of E. coli and K. pneumoniae .…”

Section: Introductionmentioning

confidence: 99%

Isolation and Characterization of Galloylglucoses Effective against Multidrug-Resistant Strains of Escherichia coli and Klebsiella pneumoniae

et al. 2022

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The search for new antibiotics against multidrug-resistant (MDR), Gram-negative bacteria is crucial with respect to filling the antibiotics development pipeline, which is subject to a critical shortage of novel molecules. Screening of natural products is a promising approach for identifying antimicrobial compounds hosting a higher degree of novelty. Here, we report the isolation and characterization of four galloylglucoses active against different MDR strains of Escherichia coli and Klebsiella pneumoniae. A crude acetone extract was prepared from Paeonia officinalis Linnaeus leaves, and bioautography-guided isolation of active compounds from the extract was performed by liquid–liquid extraction, as well as open column, flash, and preparative chromatographic methods. Isolated active compounds were characterized and elucidated by a combination of spectroscopic and spectrometric techniques. In vitro antimicrobial susceptibility testing was carried out on E. coli and K. pneumoniae using 2 reference strains and 13 strains hosting a wide range of MDR phenotypes. Furthermore, in vivo antibacterial activities were assessed using Galleria mellonella larvae, and compounds 1,2,3,4,6-penta-O-galloyl-β-d-glucose, 3-O-digalloyl-1,2,4,6-tetra-O-galloyl-β-d-glucose, 6-O-digalloyl-1,2,3,4-tetra-O-galloyl-β-d-glucose, and 3,6-bis-O-digalloyl-1,2,4-tri-O-galloyl-β-d-glucose were isolated and characterized. They showed minimum inhibitory concentration (MIC) values in the range of 2–256 µg/mL across tested bacterial strains. These findings have added to the number of known galloylglucoses from P. officinalis and highlight their potential against MDR Gram-negative bacteria.

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“…This complicates collation of published results as an organism's sensitivity to antibacterial agent varies between different isolates of even the same microbial species (Eloff, 2019). Furthermore, lower susceptibilities of clinical isolates of bacteria have been reported to plant extracts as compared to those with known resistance phenotypes (Ullah et al, 2016;Masota et al, 2021). Among all the included studies, false positives due to aspecific cytotoxicity was ruled out by testing against an array of test organisms.…”

Section: Study Characteristics and Variationsmentioning

confidence: 99%

A systematic review of antibacterial activity of polyphenolic extract from date palm (Phoenix dactylifera L.) kernel

Bhaskaracharya

Stathopoulos

2023

Front. Pharmacol.

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Background: Emergence of antibiotic-resistant bacteria makes exploration of natural antibacterial products imperative. Like other fruit processing industry by-products, date kernels, a waste from date processing industry is rich in its extractable polyphenols. The rich polyphenolic content suggests that date kernel extracts (DKE) can be a cost-effective source of antimicrobial agents, however, their antibacterial activity is poorly understood. Hence, a systematic review of available literature to establish DKE’s antibacterial activity is warranted.Methods: A systematic PRISMA approach was employed, and relevant studies were identified using defined keywords from Google Scholar, Scopus, PubMed, and Web of Science databases. The search results were screened based on predefined eligibility criteria and data extraction, organization, pooling, and descriptive statistical analyses of original research records conducted.Results: A total of 888 published records were retrieved from databases. Preliminary screening by applying specific eligibility criteria reduced records to 96 which after full text screening further decreased to 14 records. Escherichia coli and Staphylococcus aureus were the most studied organisms. Results indicate moderate to highly active effect shown by the less polar solvent based DKE’s against Gram-positive and by the aqueous based DKE’s against Gram-negative bacteria. The review confirms antibacterial activity of DKE against both Gram-positive and -negative bacteria. Heterogeneity in reported polyphenolic content and antibacterial activity are due to differences in cultivars, extraction methods, test methods, model organisms, etc. Use of standardized protocols for isolation, characterization, testing of DKE’s active polyphenols to elucidate its antibacterial activity is recommended to establish the clinical efficacy of natural antibacterial compounds from DKE.Conclusion: This review outlines the current knowledge regarding antibacterial activity of polyphenolic DKE, identifying gaps in information and provides key recommendations for future research directions.

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Reproducibility challenges in the search for antibacterial compounds from nature

Cited by 11 publications

References 49 publications

Evaluation of Biological Activity of Natural Compounds: Current Trends and Methods

Evaluation of Biological Activity of Natural Compounds: Current Trends and Methods

Isolation and Characterization of Galloylglucoses Effective against Multidrug-Resistant Strains of Escherichia coli and Klebsiella pneumoniae

A systematic review of antibacterial activity of polyphenolic extract from date palm (Phoenix dactylifera L.) kernel

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