Special Issue "Antimicrobial Activity of Higher Plants"

A special issue of Antibiotics (ISSN 2079-6382). This special issue belongs to the section "Plant-Derived Antibiotics".

Deadline for manuscript submissions: closed (30 June 2020).

Special Issue Editor

Special Issue Information

Dear Colleagues,

Humans have used higher plants to treat infections and diseases for millennia, and much of the world’s population continues to rely on plant-based medicines for treatment of infections. In developed countries, antibiotics and immunization have largely replaced plant-based antimicrobials. However, antibiotic resistance is increasing in many pathogenic microbial species, making currently used antibiotics less effective. In addition, there is an ever-increasing threat of emerging infectious diseases as humans encroach more into less inhabited areas, congregate in higher densities in population centers, and more closely associate with domesticated animals, as well as alterations in global climate and weather patterns. There is a chronic need to find alternative sources of antimicrobial agents, and higher plants still represent a large opportunity for discovery of new anti-infectious agents. We invite timely reviews and original research articles on antimicrobial activities of higher plants and antimicrobial phytochemicals derived from plants.

Prof. William N. Setzer
Guest Editor

Manuscript Submission Information

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Keywords

  • ethnopharmacology
  • phytochemistry
  • natural product drug discovery
  • antibacterial
  • antifungal
  • antiviral

Published Papers (5 papers)

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Research

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Article
Synthesis and Evaluation of the Antibacterial Activities of 13-Substituted Berberine Derivatives
Antibiotics 2020, 9(7), 381; https://doi.org/10.3390/antibiotics9070381 - 06 Jul 2020
Cited by 3 | Viewed by 944
Abstract
The biological activities of berberine, a natural plant molecule, are known to be affected by structural modifications, mostly at position 9 and/or 13. A series of new 13-substituted berberine derivatives were synthesized and evaluated in term of antimicrobial activity using various microorganisms associated [...] Read more.
The biological activities of berberine, a natural plant molecule, are known to be affected by structural modifications, mostly at position 9 and/or 13. A series of new 13-substituted berberine derivatives were synthesized and evaluated in term of antimicrobial activity using various microorganisms associated to human diseases. Contrarily to the original molecule berberine, several derivatives were found strongly active in microbial sensitivity tests against Mycobacterium, Candida albicans and Gram-positive bacteria, including naïve or resistant Bacillus cereus, Staphylococcus aureus and Streptococcus pyogenes with minimal inhibitory concentration (MIC) of 3.12 to 6.25 µM. Among the various Gram-negative strains tested, berberine’s derivatives were only found active on Helicobacter pylori and Vibrio alginolyticus (MIC values of 1.5–3.12 µM). Cytotoxicity assays performed on human cells showed that the antimicrobial berberine derivatives caused low toxicity resulting in good therapeutic index values. In addition, a mechanistic approach demonstrated that, contrarily to already known berberine derivatives causing either membrane permeabilization, DNA fragmentation or interacting with FtsZ protein, active derivatives described in this study act through inhibition of the synthesis of peptidoglycan or RNA. Overall, this study shows that these new berberine derivatives can be considered as potent and safe anti-bacterial agents active on human pathogenic microorganisms, including ones resistant to conventional antibiotics. Full article
(This article belongs to the Special Issue Antimicrobial Activity of Higher Plants)
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Article
Potential Anti-Tuberculosis Activity of the Extracts and Their Active Components of Anogeissus leiocarpa (DC.) Guill. and Perr. with Special Emphasis on Polyphenols
Antibiotics 2020, 9(7), 364; https://doi.org/10.3390/antibiotics9070364 - 29 Jun 2020
Cited by 2 | Viewed by 795
Abstract
In Sudanese traditional medicine, decoctions of the stem bark of Anogeissus leiocarpa are used for the treatment of tuberculosis (TB). However, this plant has not been investigated before for its antimycobacterial effects. Our screening results show, for the first time, that many extracts [...] Read more.
In Sudanese traditional medicine, decoctions of the stem bark of Anogeissus leiocarpa are used for the treatment of tuberculosis (TB). However, this plant has not been investigated before for its antimycobacterial effects. Our screening results show, for the first time, that many extracts of various parts of A. leiocarpa exhibit growth inhibitory activity against Mycobacterium smegmatis. Minimum inhibitory concentration (MIC) values ranged between 625 and 5000 µg/mL, with an ethyl acetate extract of the root showing the lowest MIC value. The good antimycobacterial effects of the root part could be due to its high concentration of ellagic acid derivatives, ellagitannins, and flavonoids. Thin layer chromatography (TLC) fractionation resulted in some fractions with better activity than the starting point crude methanol extract (MIC 2500 µg/mL). Those fractions with the lowest MIC values contained a high number of antioxidant compounds. Fractions 3 and 4 (MIC 1500 and 1000 µg/mL, respectively) contained high concentrations of di-methyl ellagic acid ([M-H] 329.0318). Fraction 6 (MIC 2000 µg/mL) contained a lower concentration of di-methyl ellagic acid and was not as growth inhibitory as fractions 3 and 4. Moreover, in fraction 3, an acetylated ellagic acid derivative ([M-H] 343.0477) and di-methyl-ellagic acid xyloside ([M-H] 461.0739) were tentatively characterized. Di-methyl ellagic acid xyloside was also present in fraction 4 and could strongly contribute to the antimycobacterial effect of this fraction. Additionally, protocatechuic acid ([M-H] at m/z 153.0196) was present in fraction 4. Our antimycobacterial results obtained from this research justify the use of A. leiocarpa in Sudanese folk medicine against cough related to TB. Roots, stem bark, and leaves of A. leiocarpa are sources for new potent anti-TB drug lead compounds. Full article
(This article belongs to the Special Issue Antimicrobial Activity of Higher Plants)
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Article
The Pharmaceutical Ability of Pistacia lentiscus L. Leaves Essential Oil Against Periodontal Bacteria and Candida sp. and Its Anti-Inflammatory Potential
Antibiotics 2020, 9(6), 281; https://doi.org/10.3390/antibiotics9060281 - 26 May 2020
Cited by 3 | Viewed by 1917
Abstract
Background: Given the increasing request for natural pharmacological molecules, this study assessed the antimicrobial capacity of Pistacia lentiscus L. essential oil (PLL-EO) obtained from the leaves of wild plants growing in North Sardinia (Italy) toward a wide range of periodontal bacteria and Candida, [...] Read more.
Background: Given the increasing request for natural pharmacological molecules, this study assessed the antimicrobial capacity of Pistacia lentiscus L. essential oil (PLL-EO) obtained from the leaves of wild plants growing in North Sardinia (Italy) toward a wide range of periodontal bacteria and Candida, including laboratory and clinical isolates sp., together with its anti-inflammatory activity and safety. Methods: PLL-EO was screened by gas chromatography/mass spectrometry. The minimal inhibitory concentration (MIC) was determined. The anti-inflammatory activity was measured by cyclooxygenase (COX-1/2) and lipoxygenase (LOX) inhibition, while the antioxidant capacity was determined electro-chemically and by the MTT assay. The WST-1 assay was used to ascertain cytotoxicity toward four lines of oral cells. Results: According to the concentrations of terpens, PLL-EO is a pharmacologically-active phytocomplex. MICs against periodontal bacteria ranged between 3.13 and 12.5 µg/ml, while against Candida sp. they were between 6.25 and 12.5 µg/mL. Oxidation by COX-1/2 and LOX was inhibited by 80% and 20% µg/mL of the oil, respectively. Antioxidant activity seemed negligible, and no cytotoxicity arose. Conclusions: PLL-EO exhibits a broad-spectrum activity against periodontal bacteria and Candida, with an interesting dual inhibitory capacity toward COX-2 and LOX inflammatory enzymes, and without side effects against oral cells. Full article
(This article belongs to the Special Issue Antimicrobial Activity of Higher Plants)
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Article
A Comparative Study of the in Vitro Antimicrobial and Synergistic Effect of Essential Oils from Laurus nobilis L. and Prunus armeniaca L. from Morocco with Antimicrobial Drugs: New Approach for Health Promoting Products
Antibiotics 2020, 9(4), 140; https://doi.org/10.3390/antibiotics9040140 - 25 Mar 2020
Cited by 7 | Viewed by 1407
Abstract
Laurus nobilis L. (laurel, Lauraceae) and Prunus armeniaca L. (apricot, Rosaceae) are important industrial crops and display significant biological properties, including antimicrobial activity. In this work, essential oils (EOs) prepared from the leaves of both species from Morocco were evaluated for the first [...] Read more.
Laurus nobilis L. (laurel, Lauraceae) and Prunus armeniaca L. (apricot, Rosaceae) are important industrial crops and display significant biological properties, including antimicrobial activity. In this work, essential oils (EOs) prepared from the leaves of both species from Morocco were evaluated for the first time for possible synergistic in vitro antibacterial and antifungal effects with some conventional antimicrobial drugs, namely fluconazole, ciprofloxacin and vancomycin. Samples were further evaluated for chemical composition by gas chromatography–mass spectrometry (GC-MS). The main volatile compounds detected in L. nobilis were eucalyptol (40.85%), α-terpinyl acetate (12.64%) and methyl eugenol (8.72%), while P. armeniaca was dominated essentially by (Z)-phytol (27.18%), pentacosane (15.11%), nonacosane (8.76%) and benzaldehyde (7.25%). Regarding antimicrobial activity, both EOs inhibited significantly all the microorganisms tested. The EO from L. nobilis had the highest activity, with minimal inhibitory concentrations (MICs) ranging from 1.39 to 22.2 mg/mL for bacteria and between 2.77 and 5.55 mg/mL for yeasts. Conversely, the combination of the studied EOs with ciprofloxacin, vancomycin and fluconazol resulted in a noteworthy decrease in their individual MICs. In fact, of the 32 interactions tested, 23 (71.87%) demonstrated total synergism and 9 (28.12%) a partial synergistic interaction. The EO from L. nobilis exhibited the highest synergistic effect with all the antibiotics used, with fractional inhibitory concentration (FIC) index values in the range of 0.266 to 0.75 for bacteria, and between 0.258 and 0.266 for yeast. The synergistic interaction between the studied EOs and standard antibiotics may constitute promising anti-infective agents useful for treating diseases induced by antibiotic-resistant pathogens. Full article
(This article belongs to the Special Issue Antimicrobial Activity of Higher Plants)

Review

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Review
Cannabinoids-Promising Antimicrobial Drugs or Intoxicants with Benefits?
Antibiotics 2020, 9(6), 297; https://doi.org/10.3390/antibiotics9060297 - 02 Jun 2020
Cited by 5 | Viewed by 1894
Abstract
Novel antimicrobial drugs are urgently needed to counteract the increasing occurrence of bacterial resistance. Extracts of Cannabis sativa have been used for the treatment of several diseases since ancient times. However, its phytocannabinoid constituents are predominantly associated with psychotropic effects and medical applications [...] Read more.
Novel antimicrobial drugs are urgently needed to counteract the increasing occurrence of bacterial resistance. Extracts of Cannabis sativa have been used for the treatment of several diseases since ancient times. However, its phytocannabinoid constituents are predominantly associated with psychotropic effects and medical applications far beyond the treatment of infections. It has been demonstrated that several cannabinoids show potent antimicrobial activity against primarily Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA). As first in vivo efficacy has been demonstrated recently, it is time to discuss whether cannabinoids are promising antimicrobial drug candidates or overhyped intoxicants with benefits. Full article
(This article belongs to the Special Issue Antimicrobial Activity of Higher Plants)
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