Plant products as antimicrobial agents

Screening Evaluation of Antiproliferative, Antimicrobial and Antioxidant Activity of Lichen Extracts and Secondary Metabolites In Vitro

Lichen metabolites represent a wide range of substances with a variety of biological effects. The present study was designed to analyze the potential antiproliferative, antimicrobial and antioxidative effects of several extracts from lichens (Pseudevernia furfuracea, Lobaria pulmonaria, Cetraria islandica, Evernia prunastri, Stereocaulon tomentosum, Xanthoria elegans and Umbilicaria hirsuta) and their secondary metabolites (atranorin, physodic acid, evernic acid and gyrophoric acid). The crude extract, as well as the isolated metabolites, showed potent antiproliferative, cytotoxic activity on a broad range of cancer cell lines in 2D (monolayer) and 3D (spheroid) models. Furthermore, antioxidant (2,2-diphenyl-1-picryl-hydrazylhydrate (DPPH) and in vitro antimicrobial activities were assessed. Data showed that the lichen extracts, as well as the compounds present, possessed biological potential in the studied assays. It was also observed that the extracts were more efficient and their major compounds showed strong effects as antiproliferative, antioxidant and antibacterial agents. Moreover, we demonstrated the 2D and 3D models' importance to drug discovery for further in vivo studies. Despite the fact that lichen compounds have been neglected by the scientific community for long periods, nowadays they are objects of investigation based on their promising effects.

Dietary Supplementation with Botanical Blends Modified Intestinal Microbiota and Metabolomics of Weaned Pigs Experimentally Infected with Enterotoxigenic Escherichia coli

The objective of this study was to investigate supplementation of botanical blends (BB) comprised of 0.3% capsicum oleoresin and 12% garlic oil on gut microbiota and metabolomic profiles in serum and ileal mucosa of Escherichia coli infected pigs. Sixty weaned pigs were assigned to one of five treatments: negative control (CON-), positive control (CON+), dietary supplementation of 100 ppm BB1, 50 or 100 ppm BB2. All pigs, except CON-, were orally inoculated with 10¹⁰ CFU F18 ETEC/3-mL dose for 3 consecutive days after 7 d adaption. Feces, ileal digesta and cecal content were collected for 16S rRNA amplicon sequencing. Serum and ileal mucosa underwent primary metabolomics analysis. Supplementing 100 ppm BB1 increased (p < 0.05) relative abundances of Enterobacteriaceae and Escherichia-Shigella in ileum, and the relative abundances of Bacteroidota and Prevotellaceae in cecum than CON+ on d 5 post-inoculation (PI). Supplementing 100 ppm BB2 upregulated serum pinitol on d 4 PI and serum cholesterol and aminomalonic acids on d 21 PI, while supplementing 50 ppm BB2 reduced asparagine in ileal mucosa on d 5 PI than CON+. Supplementation with botanical blends modulated ileal and cecal microbiota and serum metabolomics profiles in weaned pigs under Escherichia coli challenge.

Antimicrobial Compounds in Food Packaging

This review presents current knowledge on antimicrobial agents that are already used in the food packaging industry. At the beginning, innovative ways of food packaging were discussed, including how smart packaging differs from active packaging, and what functions they perform. Next, the focus was on one of the groups of bioactive components that are used in these packaging, namely antimicrobial agents. Among the antimicrobial agents, we selected those that have already been used in packaging and that promise to be used elsewhere, e.g., in the production of antimicrobial biomaterials. Main groups of antimicrobial agents (i.e., metals and metal oxides, organic acids, antimicrobial peptides and bacteriocins, antimicrobial agents of plant origin, enzymes, lactoferrin, chitosan, allyl isothiocyanate, the reuterin system and bacteriophages) that are incorporated or combined with various types of packaging materials to extend the shelf life of food are described. The further development of perspectives and setting of new research directions were also presented.

Bioactive compounds as an alternative for the sugarcane industry: Towards an integrative approach

Here, a comprehensive review of sugarcane industrialization and its relationship with bioactive compounds (BCs) detected in various products and by-products generated during its processing is presented. Furthermore, it is discussed how these compounds have revealed important antioxidant, antineoplastic, antidiabetic, and antimicrobial activities. From this bibliographic research highlights the significance of two types of BCs of natural origin (phenolic compounds (PCs) and terpenoids) and a group of compounds synthesized during industrial transformation processes (Maillard reaction products (MRPs)). It was found that most of the studies about the BCs from sugarcane have been conducted by identifying, isolating, and analyzing ones or a few compounds at a specific period, this being a conventional approach. However, given the complexity of the synthesis processes of all these BCs and the biological activities they can manifest in a specific biological context, novel approaches are needed to address these analyses holistically. To overcome this challenge, integrating massive and multiscale methods, such as omics sciences, seems necessary to enrich these studies. This work is intended to contribute to the state of the art that could support future research about the exploration, characterization, or evaluation of different bioactive molecules from sugarcane and its derivatives.

Inhibitory Activity of Saussurea costus Extract against Bacteria, Candida, Herpes, and SARS-CoV-2

Medicinal herbs have long been utilized to treat various diseases or to relieve the symptoms of some ailments for extended periods. The present investigation demonstrates the phytochemical profile, molecular docking, anti-Candida activity, and anti-viral activity of the Saussurea costus acetic acid extract. GC-MS analysis of the extract revealed the presence of 69 chemical compounds. The chemical compounds were alkaloids (4%), terpenoids (79%), phenolic compounds (4%), hydrocarbons (7%), and sterols (6%). Molecular docking was used to study the inhibitory activity of 69 identified compounds against SARS-CoV-2. In total, 12 out of 69 compounds were found to have active properties exhibiting SARS-CoV-2 inhibition. The binding scores of these molecules were significantly low, ranging from -7.8 to -5.6 kcal/mol. The interaction of oxatricyclo [20.8.0.0(7,16)] triaconta-1(22),7(16),9,13,23,29-hexaene with the active site is more efficient. Furthermore, the extract exhibited significant antimicrobial activity (in vitro) against Candida albicans, which was the most susceptible microorganism, followed by Bacillus cereus, Salmonella enterica, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, respectively. On the other hand, its antiviral activity was evaluated against HSV-1 and SARS-CoV-2, and the results showed a significant positive influence against HSV-1 (EC₅₀ = 82.6 g/mL; CC₅₀ = 162.9 g/mL; selectivity index = 1.9). In spite of this, no impact could be observed in terms of inhibiting the entry of SARS-CoV-2 in vitro.

Potent Inhibitory Activity of Natural Product Anaephene B and Analogues against Leishmania tarentolae In Vitro

In this study, a specific alkylphenol natural product, anaephene B, and its unique synthesized derivatives were tested for their inhibitory effect on the protozoan parasite Leishmania tarentolae. In a series of cell viability tests and enzyme assays, these test compounds have produced interesting results with regard to their antibiotic effect, showing similar potency against L. tarentolae as they do against drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA). All compounds tested in this study have shown the ability to completely inhibit our model system, L. tarentolae, in vitro. This study helps increase our understanding of the structure-activity relationship (SAR) between anaephene B and its analogues for a new class of potential pharmaceuticals for the treatment of Leishmania infections.

Plants from a semi-arid environment as a source of phytochemicals against Fusarium crown and foot rot in zucchini

Fusarium crown and foot rot, caused by F. solani f. sp. cucurbitae, are major fungal diseases affecting zucchini and other cucurbits. Despite the efficacy of synthetic fungicides, their health and environmental hazards have highlighted the urgent need for safer alternatives, such as phytochemical-based biocides. Owing to the upregulation of the plant secondary metabolism under stressful conditions, bioprospecting in harsh environments could reveal ore plants for bioactive metabolites. In this study, thirteen wild plants were collected from their natural habitat in a semiarid environment (Yanbu, Saudi Arabia) and extracted to obtain phenolics rich extracts. Total polyphenols, flavonoids, antioxidant capacities and the antifungal activities of the extracts against a pathogenic isolate of F. solani were assessed. Fusarium solani was isolated from infected zucchini and characterized by scanning electron microscopy. Hierarchical clustering analysis of the phytochemical screening and in vitro bioactivity revealed that Rosmarinus officinalis, Pulicaria crispa, Achillea falcata and Haloxylon salicornicum were the richest in polyphenols and the most powerful against F. solani. Further, the extracts of these four plants significantly decreased the disease incidence in zucchini, where P. crispa was the premier. Interestingly, results of transmission electron microscopy revealed that extract of P. crispa, as a representative of the powerful group, induced ultrastructural disorders in fungal cells. Therefore, this study suggests the use of R. officinalis, P. crispa, A. falcata and H. salicornicum grown in semi-arid environments as ore plants to develop phytochemical-based biocides against Fusarium crown and foot rot.

Antimicrobial potential of the Mayan medicine plant Matayba oppositifolia (A. Rich.) Britton against antibiotic-resistant priority pathogens

ETHNOPHARMACOLOGICAL RELEVANCE

The bark of Matayba oppositifolia (A. Rich.) Britton (commonly known as "huaya" or "palo huacax") is commonly utilized in traditional Mayan medicine for treating diarrhea and for canker and other sores.

AIM OF THE STUDY

The aim of this study was to investigate the in-vitro antimicrobial activity of M. oppositifolia bark extracts against drug-susceptible and -resistant ESKAPE-E pathogens. In addition, the phytochemical composition of the best antibacterial extract was analyzed.

MATERIALS AND METHODS

The bark extracts were prepared with different solvents, including water, n-hexane, ethyl acetate and methanol. These were tested against ESKAPE-E (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp., including Escherichia coli) strains using Resazurin Microtiter Assay. In addition, the composition of the most active extract was analyzed by GC-MS.

RESULTS

The aqueous and organic bark extracts showed activity on drug-susceptible and -resistant ESKAPE-E microbes (MIC = 1000-31.25 μg/mL). The n-hexane bark extract was more active against the superbugs carbapenem-resistant K. pneumoniae (MIC = 500-31.25 μg/mL) and A. baumannii (MIC = 250-125 μg/mL). The GC-MS analysis of this extract allowed the identification of 12 phytochemicals as the potential antibacterial compounds. The major compounds identified were palmitic acid (1), friedelan-3-one (2) and 7-dehydrodiosgenin (3).

CONCLUSION

The present study reveals the strong in-vitro antibacterial activity of the n-hexane extract from the bark of M. oppositifolia and demonstrates the potential of natural products as a source of antibacterial compounds or phytomedicines that are specifically effective against drug-resistant ESKAPE-E bugs. Additionally, our investigation contributes to the ethnopharmacological knowledge and reappraisal of Mayan medicinal flora, as well as supports the traditional use of the bark of the medicinal plant M. oppositifolia for the treatment of infectious diseases.

Valorization of Bioactive Compounds from Two Underutilized Wild Fruits by Microencapsulation in Order to Formulate Value-Added Food Products

Currently, microencapsulation has become a viable method of nutrient delivery for the food industry. This work microencapsulated the bioactive compounds extracted from two neglected species (Balanites aegyptiaca and Ziziphus mauritiana) by freeze-drying. A combination of wall materials (whey protein and pectin; soy protein and maltodextrin) was chosen to prepare the microcapsules. The phytochemical and physicochemical characterization of the microcapsules was then carried out. The encapsulation yield ranged from 82.77% to 96.05% for Balanites and Ziziphus, respectively, whereas the efficiency was 76.18 ± 1.39% and 80.93 ± 1.71%. The stimulated in vitro gastrointestinal test showed that encapsulation increased the bioavailability of the bioactive compounds. The total carotenoids were the most bioavailable compounds with 85.89 ± 0.06% for Ziziphus and 70.46 ± 1.10% for Balanites, followed by total flavonoids for Zizyphus with 63.27 ± 1.56%. Furthermore, regardless of species or wavelengths, the HPLC analysis resulted in the identification of 17 bioactive metabolites. The predominant one was epicatechin, whose level ranged from 231.52 ± 5.06 to 250.99 ± 3.72 mg/100 g DW in Ziziphus and 91.80 ± 3.85 to 116.40 ± 4.09 mg/100 g DW in Balanites. In estimating the enzyme inhibition and antioxidant power, both studied fruits showed antidiabetic, inflammatory, and antioxidant effects. These findings suggest that natural bioactive compounds are abundant in the fruits of Z. mauritiana and B. aegyptiaca and could be a valuable source for the food and pharmaceutical industries.

Marine bioactive compounds as antibiofilm agent: a metabolomic approach

The ocean is a treasure trove of both living and nonliving creatures, harboring incredibly diverse group of organisms. A plethora of marine sourced bioactive compounds are discovered over the past few decades, many of which are found to show antibiofilm activity. These are of immense clinical significance since the formation of microbial biofilm is associated with the development of high antibiotic resistance. Biofilms are also responsible to bring about problems associated with industries. In fact, the toilets and wash-basins also show degradation due to development of biofilm on their surfaces. Antimicrobial resistance exhibited by the biofilm can be a potent threat not only for the health care unit along with industries and daily utilities. Various recent studies have shown that the marine members of various kingdom are capable of producing antibiofilm compounds. Many such compounds are with unique structural features and metabolomics approaches are essential to study such large sets of metabolites. Associating holobiome metabolomics with analysis of their chemical attribute may bring new insights on their antibiofilm effect and their applicability as a substitute for conventional antibiotics. The application of computer-aided drug design/discovery (CADD) techniques including neural network approaches and structured-based virtual screening, ligand-based virtual screening in combination with experimental validation techniques may help in the identification of these molecules and evaluation of their drug like properties.

Evaluation of antibacterial, antioxidant, and anti-inflammatory properties of GC/MS characterized methanol leaf extract of Terminalia superba (Combretaceae, Engl. & Diels)

Background

Terminalia superba is a well-known medicinal plant used in folk medicine for the management of various diseases and swelling. Validation of its efficacy in standardized scientific models is lacking. This gap needs to be filled as a way of enhancing modern drug discovery. The aim is to evaluate the antibacterial, antioxidant, and anti-inflammatory properties of T. superba in known and established models. Also, to establish and possibly correlate the established activity with the phytochemicals identified using GC/MS and qualitative methods.

Results

The result showed a dose-dependent percentage inhibition of DPPH, HO•, and Fe3+ reducing activity. The antibacterial activity showed dose-dependent significant (p < 0.05) inhibition against all the organisms used. The anti-inflammatory activity of METS was confirmed in the carrageenan model with significant (p < 0.05) inhibition of paw volume when compared to control while significantly decreasing (p < 0.05) weight of xylene-induced ear. For instance, after 6 h, there was  a reduction of 42%, 33%, and 22% for diclofenac, 200 mg, and 100 mg, respectively, as against 4% in control. The significant (p < 0.05) increase in MDA was attenuated by the treatment with METS dose dependently. Phytochemical assay and GC/MS characterization showed that alkaloids, saponins, phenols, quinone, tannins, coumarins, proteins, flavonoids, and amino acids were dominant with fatty acids accounting for 53%. Others are esters (23%), organic compounds (12%), alkanes (9%), and carboxylic acids (3%).

Conclusions

T. superba possesses antioxidant, antibacterial, and anti-inflammatory properties which are believed to arise from the secondary metabolites observed in the GC–MS characterization.

Graphical Abstract

Antimicrobial Activities of Ganoderma mbrekobenum Strain EGDA (Agaricomycetes) from Egypt

Ganoderma is a well-known genus of medicinal mushrooms. The biological activity of the fruiting bodies of G. mbrekobenum (previously identified as Ganoderma sp. EGDA, (AC: LN774971) is scarcely studied. The microorganisms including bacteria and fungi were chosen for screening of the antimicrobial activity produced by G. mbrekobenum strain EGDA. The bioactive compounds were extracted from aqueous, petroleum ether, chloroform, ethyl acetate, and methanol extracts. The higher antibacterial activity produced by methanol extract was against Bacillus subtilis and B. cereus (14.13 ± 0.12 mm, 13.03 ± 0.12 mm, respectively). Water fraction showed antibacterial effect against most of the test bacterial strains. The highest antifungal activity produced by methanol extract was against Fusarium oxysporum I and F. oxysporum f. sp. lycopersici (16.37 ± 0.03 mm 15.67 ± 0.19 mm, respectively). Gas chromatography/mass spectrometry analysis of the separated fractions revealed the identification of 46 compounds.

Feasibility of the crude extracts of Amorphophallus paeoniifolius and Colocasia esculenta as intracanal medicaments in endodontic therapy in comparison to the 940 nm diode laser: An in vitro antimicrobial study

Background/purpose

The elimination and debridement of intracanal bacteria are credited with long-term effectiveness in endodontic therapy. This study aimed to compare the antimicrobial efficacies of Amorphophallus paeoniifolius (Suran), Colocasia esculenta (Aravi) crude extracts as intracanal medicaments with calcium hydroxide (CH), 2% chlorhexidine (CHX) gel, and 940 nm diode laser.

Materials and methods

Fifty-eight intact, single-root, extracted human mandibular premolar teeth were prepared. The samples were sterilized, transferred into microcentrifuge tubes, and inoculated with E. faecalis. The samples were placed in an incubator for three weeks to allow the biofilm to grow. Then the samples were randomly divided into five experimental groups (n = 10), disinfected with Suran, Aravi crude extracts, CH, 2% CHX gel, and a 940 nm diode laser. The negative control group (n = 4) and the positive control group (n = 4). Then the samples were observed under light and scanning electron microscopy to monitor the E. faecalis biofilm. The sampling method was carried out in paper point (intracanal) and Peeso bur (intradentinal). Later the number of colony-forming units was counted and analyzed.

Results

Colony-forming units were significantly reduced in the 2% CHX gel in both sampling methods, while Suran showed lower colony-forming units compared to Aravi and CH. The differences between experimental groups were not statistically significant (P > 0.05) in both sampling methods.

Conclusion

This study showed that the application of Suran and Aravi crude extracts as intracanal medicaments leads to a significant reduction in the number of bacterial colonies compared to CH, 2% CHX gel, and 940 nm diode laser.

Antibacterial Activity Against Multidrug-Resistant Clinical Isolates of Nine Plants from Chencha, Southern Ethiopia

Background

The diminishing efficacy of antibiotics currently in use and the emergence of multidrug-resistant bacteria pose a grave threat to public health worldwide. Hence, new classes of antimicrobials are urgently required, and the search is continuing.

Methods

Nine plants were chosen for the current work, which are collected from the highlands of Chencha, Ethiopia. Plant extracts containing secondary metabolites in various organic solvents were checked for antibacterial activity against type culture bacterial pathogens and MDR clinical isolates. The broth dilution technique was used to evaluate the minimum inhibitory and minimum bactericidal concentrations of highly active plant extracts, and time-kill kinetic and cytotoxic assays were performed using the most active plant extract.

Results

Two plants (C. asiatica and S. marianum) were highly active against ATCC isolates. The EtOAc extract of C. asiatica produced the highest zone of inhibition ranging between 18.2±0.8-20.7±0.7 and 16.1±0.4-19.2±1.4 mm against Gram-positive and Gram-negative bacteria, respectively. The EtOH extract of S. marianum displayed zones of inhibition in the range of 19.9±1.4-20.5±0.7 mm against the type culture bacteria. The EtOAc extract of C. asiatica effectively curbed the growth of six MDR clinical isolates. The MIC values of C. asiatica against the Gram-negative bacteria tested were 2.5 mg/mL, whereas the corresponding MBC values were 5 mg/mL in each case. The MIC and MBC values were the lowest in the case of Gram-positive bacteria, ie, 0.65 and 1.25 mg/mL, respectively. A time-kill assay showed the inhibition of MRSA at 4 × MIC and 8 × MIC within 2 hours of incubation. The 24 h LD₅₀ values of C. asiatica and S. marianum corresponding to Artemia salina were 3.05 and 2.75 mg/mL, respectively.

Conclusion

Overall results substantiate the inclusion of C. asiatica and S. marianum as antibacterial agents in traditional medicines.

Insight into the phytochemical profile and antimicrobial activities of Amomum subulatum and Amomum xanthioides: an in vitro and in silico study

Introduction

Medicinal plants have been considered as potential source of therapeutics or as starting materials in drugs formulation.

Methods

The current study aims to shed light on the therapeutic potential of the Amomum subulatom and Amomum xanthioides Fruits by analyzing the phytochemical composition of their seeds and fruits using gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) techniques to determine the presence of bioactive components such as flavonoids, phenols, vitamins, steroids, and essential oils.

Results and Discussion

The protein content is usually higher than the total lipids in both species except the fruit of A. subulatum which contain more lipids than proteins. The total protein contents for A. subulatum were 235.03 ± 21.49 and 227.49 ± 25.82 mg/g dry weight while for A. xanthioides were 201.9 ± 37.79 and 294.99 ± 37.93 mg/g dry weight for seeds and fruit, respectively. The Carvacrol levels in A. subulatum is 20 times higher than that in A. xanthioides. Lower levels of α-Thujene, Phyllanderenes, Ascaridole, and Pinocarvone were also observed in both species. According to DPPH (2,2-diphenylpicrylhydrazyl) assay, seed the extract of A. subulatum exhibited the highest antioxidant activity (78.26±9.27 %) followed by the seed extract of A. xanthioides (68.21±2.56 %). Similarly, FRAP (Ferric Reducing Antioxidant Power) assay showed that the highest antioxidant activity was exhibited by the seed extract of the two species; 20.14±1.11 and 21.18±1.04 µmol trolox g-1 DW for A. subulatum and A. xanthioides, respectively. In terms of anti-lipid peroxidation, relatively higher values were obtained for the fruit extract of A. subulatum (6.08±0.35) and the seed extract of A. xanthioides (6.11±0.55). Ethanolic seed extracts of A. subulatum had the highest efficiency against four Gram-negative bacterial species which causes serious human diseases, namely Pseudomonas aeruginosa, Proteus vulgaris, Enterobacter aerogenes, and Salmonella typhimurium. In addition, P. aeruginosa was also inhibited by the fruit extract of both A. subulatum and A. xanthioides. For the seed extract of A. xanthioides, large inhibition zones were formed against P. vulgaris and the fungus Candida albicans. Finally, we have in silico explored the mode of action of these plants by performing detailed molecular modeling studies and showed that the antimicrobial activities of these plants could be attributed to the high binding affinity of their bioactive compounds to bind to the active sites of the sterol 14-alpha demethylase and the transcriptional regulator MvfR.

Conclusion

These findings demonstrate the two species extracts possess high biological activities and therapeutical values, which increases their potential value in a number of therapeutic applications.

Targeting dormant phenotype acquired mycobacteria using natural products by exploring its important targets: In vitro and in silico studies

The dormant phenotype of Mycobacterium tuberculosis that develops during infection poses a major challenge in disease treatment, since these bacilli show tolerance to front-line drugs. An in vitro hypoxia dormancy model was established, which produced phenotypically dormant Mycobacterium smegmatis after prolonged incubation under conditions of low oxygen, low pH, and nutrient limitation. Bacilli in this model displayed the classical dormancy characters, including loss of acid fastness, altered morphology, and, most importantly, tolerance to front-line drugs. The dormant form of M. smegmatis was treated with drugs and phytomolecules. Three phytomolecules exhibited activity against dormant bacilli, as shown by lack of regrowth in solid and liquid media. Further investigation of dormancy-active hits was carried out using in silico approaches to understand the druggable targets of these phytomolecules in dormant bacilli. For this study, molecular docking, molecular dynamics simulations (MDS), and molecular mechanics-generalized born solvent accessibility (MM-GBSA)-based binding energy (ΔG_bind) calculations were performed. Five different targets, namely, isocitrate lyase (ICL), GMP synthase, LuxR, DosR, and serine/threonine protein kinase (STPK), from M. smegmatis and M. tuberculosis were studied in details. DosR and STPK were found to be the common targets in both the species that were more prone to the phytomolecules. The standard DosR inhibitor, HC104A, showed a lower dock score and binding energy of -4.27 and -34.50 kcal/mol, respectively, compared to the natural products under study. The phytomolecule, icariin, showed better docking score (dock score = -5.92 kcal/mol with and binding energy ΔG_bind= -52.96 kcal/mol) with DosR compared to known DosR inhibitor, HC104A (dock score = -4.27 kcal/mol and binding energy ΔG_bind = -34.50 kcal/mol). Similarly, the known STPK inhibitor MRCT67127 showed a lower dock score and binding energy of -4.25 and -29.43 kcal/mol, respectively, compared to the phytomolecule, icariin (dock score = -5.74 kcal/mol and ΔG_bind= -43.41 kcal/mol). These compounds might ultimately lead to new therapeutics or may be useful as adjuvants to the first-line drugs to reduce the lengthy anti-TB therapy in the future.

Large-Scale Transposon Mutagenesis Reveals Type III Secretion Effector HopR1 Is a Major Virulence Factor in Pseudomonas syringae pv. actinidiae

Bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae (Psa) is a serious threat to kiwifruit production worldwide. Four biovars (Psa biovar 1; Psa1, Psa biovar 3; Psa3, Psa biovar 5; Psa5, and Psa biovar 6; Psa6) were reported in Japan, and virulent Psa3 strains spread rapidly to kiwifruit production areas worldwide. Therefore, there is an urgent need to develop critical management strategies for bacterial canker based on dissecting the dynamic interactions between Psa and kiwifruit. To investigate the molecular mechanism of Psa3 infection, we developed a rapid and reliable high-throughput flood-inoculation method using kiwifruit seedlings. Using this inoculation method, we screened 3000 Psa3 transposon insertion mutants and identified 91 reduced virulence mutants and characterized the transposon insertion sites in these mutants. We identified seven type III secretion system mutants, and four type III secretion effectors mutants including hopR1. Mature kiwifruit leaves spray-inoculated with the hopR1 mutant showed significantly reduced virulence compared to Psa3 wild-type, indicating that HopR1 has a critical role in Psa3 virulence. Deletion mutants of hopR1 in Psa1, Psa3, Psa5, and Psa6 revealed that the type III secretion effector HopR1 is a major virulence factor in these biovars. Moreover, hopR1 mutants of Psa3 failed to reopen stomata on kiwifruit leaves, suggesting that HopR1 facilitates Psa entry through stomata into plants. Furthermore, defense related genes were highly expressed in kiwifruit plants inoculated with hopR1 mutant compared to Psa wild-type, indicating that HopR1 suppresses defense-related genes of kiwifruit. These results suggest that HopR1 universally contributes to virulence in all Psa biovars by overcoming not only stomatal-based defense, but also apoplastic defense.

An Assessment of the In Vitro Models and Clinical Trials Related to the Antimicrobial Activities of Phytochemicals

An increased number antibiotic-resistant bacteria have emerged with the rise in antibiotic use worldwide. As such, there has been a growing interest in investigating novel antibiotics against antibiotic-resistant bacteria. Due to the extensive history of using plants for medicinal purposes, scientists and medical professionals have turned to plants as potential alternatives to common antibiotic treatments. Unlike other antibiotics in use, plant-based antibiotics have the innate ability to eliminate a broad spectrum of microorganisms through phytochemical defenses, including compounds such as alkaloids, organosulfur compounds, phenols, coumarins, and terpenes. In recent years, these antimicrobial compounds have been refined through extraction methods and tested against antibiotic-resistant strains of Gram-negative and Gram-positive bacteria. The results of the experiments demonstrated that plant extracts successfully inhibited bacteria independently or in combination with other antimicrobial products. In this review, we examine the use of plant-based antibiotics for their utilization against antibiotic-resistant bacterial infections. In addition, we examine recent clinical trials utilizing phytochemicals for the treatment of several microbial infections.

Bioassay-guided isolation and characterization of lead antimicrobial compounds from Acacia hydaspica plant extract

Acacia hydaspica possesses varied pharmacological attributes. We aimed to examine the antimicrobial potential and isolate the active antimicrobial metabolites. The plant extract was fractionated and the antimicrobial activity of the crude extract, fractions and compounds was tested by agar well diffusion and agar tube dilution and broth dilution methods. Bacterial strains selected for bioactivity testing were Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii while selected strains from kingdom fungi were Candida albicans, Cryptococcus neoformans, Fusarium solani and Aspergillus. The active compounds were isolated from Acacia hydaspica by bioassay-guided fractionation and identified by nuclear magnetic resonance and spectroscopic techniques. S. aureus cell surface proteins, Autolysins (Atl), Clumping factor A (ClfA), and Fibronectin Binding Proteins (FnBP), were molecularly docked with Catechin 3-O-gallate (CG) and Methyl gallate (MG) and binding energy and molecular interactions between the proteins and compounds were analyzed. Ethyl acetate (AHE) and Butanol (AHB) fractions of A. hydaspica were the most active fractions against tested microbial strains. Therefore, both were subjected to bioassay-directed fractionation which led to the isolation of one pure active antimicrobial AHE and one active pure compound from AHB fraction besides active enriched isolates. Methyl-gallate (MG) and catechin-3-gallate (CG) are active compounds extracted from AHE and AHB fractions respectively. In antibacterial testing MG significantly inhibited the growth of E. coli (MIC₅₀ = 21.5 µg/ml), B. subtilus (MIC₅₀ = 23 µg/ml) and S. aureus (MIC₅₀ = 39.1 µg/ml) while moderate to low activity was noticed against other tested bacterial strains. Antifungal testing reveals that MG showed potent antifungal activity against F. solani (MIC₅₀ = 33.9 µg/ml) and A. niger (MIC₅₀ = 41.5 µg/ml) while lower antifungal activity was seen in other tested strains. AHB fractions and pure compound (CG) showed specific antibacterial activity against S. aureus only (MIC₅₀ = 10.1 µg/ml) while compound and enriched fractions showed moderate to no activity against other bacterial and fungal strains respectively. Molecular docking analysis revealed that CG interacted more strongly with the cell surface proteins than MG. Among these proteins, CG made a stronger complex with ClfA (binding affinity - 9.7) with nine hydrophobic interactions and five hydrogen bonds. Methyl gallate (MG) and catechin 3-O-gallate (CG) are the major antimicrobial compound from A. hydaspica that inhibit the growth of specific microbes. The occurrence of MG and CG endorse the traditional antimicrobial applicability of A. hydaspica, and it can be a legitimate alternative to control specific microbial infections.

Synthesis and Fabrication of a Betulin-Containing Polyolefin Electrospun Fibrous Mat for Antibacterial Applications

Biocompounds play a significant role in the area of renewable polymers in terms of sustainability, as they can be employed or converted into monomers for polymerization in a manner similar to many petroleum-derived monomers. In this work, betulin, a plant-derived triterpene with antibacterial and antiviral properties, was converted to two kinds of α,ω-diene derivatives with different methylene spacer lengths between the olefin and the ester group via an esterification reaction. Polyolefins were subsequently made by acyclic diene metathesis (ADMET) polymerization of betulin-based α,ω-diene. The polymer consists of rigid betulin and flexible unsaturated aliphatic segments, which was confirmed by NMR spectroscopy and gel permeation chromatography (GPC). The influence of different parameters including temperature, catalysts, and catalyst loading on ADMET polymerization was investigated. These polyolefins with high molar mass (up to 20.0 kg/mol) were obtained in an elevated yield (≥95%). Thermal analysis of these (co)polymers showed excellent thermal stability (up to 360 °C) and tunable glass transition temperatures depending on the nature of betulin and alkene segments. To evaluate the antimicrobial potential of betulin-containing polymers, the fabrication of polyolefin fibrous mats (ca. 400 nm diameter) via the electrospinning technique was successfully achieved. Their morphology and hydrophobicity were studied by scanning electron microscopy (SEM) and water contact angle analyses. The fibrous mats possessed broad-spectrum antibacterial property, providing a feasible strategy to design betulin-based polymeric fibers for many applications in the biomedical field.

Chemical Profile and Skin-Beneficial Activities of the Petal Extracts of Paeonia tenuifolia L. from Serbia

Without being aware of its chemical makeup, many ancient societies have used Steppe peony in their traditional medicine. Given that modern phytopreparation intended for use on human skin requires, above all, knowledge of its chemical composition, the goal of this study was to make a screening of the composition of aqueous and methanolic extracts of the petals of P. tenuifolia L. and to examine them for various skin-beneficial properties. The extracts were prepared by maceration, ultrasound-assisted, and microwave-assisted extraction procedures. The chemical profiling was conducted by the use of UHPLC-LTQ-OrbiTrap MS and UHPLC/MS, and spectrophotometric methods for the determination of total polyphenol and total flavonoid contents. The biological activities entailed antioxidant ABTS, DPPH, CUPRAC (Cupric Ion Reducing Antioxidant Capacity), and FRAP (Ferric Reducing Antioxidant Power) assays, antimicrobial (antibacterial and antifungal) and antibiofilm activities, cytotoxicity, wound healing potential, as well as the adhesion and invasion of Staphylococcus lugdunensis. The results showed that the petals are rich in phenolic acids and flavonoids, which are commonly associated with numerous biological activities. The aqueous extracts were more efficient in the majority of the bioactivity assays then the methanolic ones, whereas the optimal extraction method varied between the assays. This study is the first step towards the safe use of the aqueous extracts of P. tenuifolia petals for therapeutic skin treatments.

Mineral contents, antimicrobial profile, acute and chronic toxicity of the aqueous extract of Moroccan Thymus vulgaris in rodents

Moroccan flora is rich in plants used in traditional medicine, but the further scientific investigation is necessary. The aim of the research was to evaluate the nutritional content and antimicrobial activity of Moroccan Thymus vulgaris, as well as its possible acute and chronic toxicological effects on rodents. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to determine the mineral content. The antimicrobial activity was determined using a well-diffusion test, a minimum inhibitory concentration (MIC), and a minimum bactericidal/fungicidal concentration (MBC/MFC) assay. Acute and chronic toxicity studies were conducted in vivo on mice and rats, respectively. Following that, haematological, serum-biochemistry, and histological investigations were performed. Moroccan Thyme was shown to be a source of numerous minerals which are necessary for health promotion. All antimicrobial testing, disc diffusion, MIC, and MBC tests revealed that thyme had potent antibacterial activity against all microorganisms tested. Staphylococcus aureus was the most susceptible bacterium, followed by Salmonella enterica and Escherichia coli. Additionally, thyme exhibited great antifungal efficacy against Candida albicans. The acute toxicity results indicated that the aqueous extract of T. vulgaris is almost non-toxic when taken orally. According to the chronic toxicity study, the extract is generally safe when taken orally over an extended period of time. The biochemical and haematological characteristics of the serum and blood were within acceptable limits, and histological examination revealed no abnormalities. In conclusion, the findings of this investigation, confirm the antimicrobial efficacy of the aqueous extract of Moroccan T. vulgaris and its safety for experimental animals.

Antibacterial and antibiotic-potentiation activity of the constituents from aerial part of Donella welwitshii (Sapotaceae) against multidrug resistant phenotypes

Background

The rise of multidrug-resistant (MDR) bacteria is a real public health problem worldwide and is responsible for the increase in hospital infections. Donella welwitschii is a liana or shrub belonging to the family Sapotaceae and traditionally used to cure coughs.

Objective

This study was conducted with the objective to validate the medicinal properties of this plant, the aerial part was studied for its phytochemical composition using column and PTLC chromatography and exploring its antibacterial and antibiotic-modifying activity as well as those of its phytochemicals.

Methods

The structures of the compounds were elucidated from their physical and spectroscopic data in conjunction with literature. The antibacterial activity of the isolated metabolites was performed toward a panel of MDR Gram negative and Gram-positive bacteria. The broth micro-dilution method was used to determine antibacterial activities, efflux pump effect using the efflux pump inhibitor (EPI) (phenylalanine-arginine-ß-naphthylamide (PAβN)), as well as the modulating activity of antibiotics. Monitoring the acidification of the bacterial growth medium was used to study the effects of the samples on the bacterial proton-ATPase pumps and cellular ATP production.

Results

Eleven compounds were isolated including pentacyclic triterpenes, C-glucosyl benzophenones. With a MIC value < 10 μg/mL, diospyric acid (7) significantly inhibited the growth of Escherichia coli AG102, Enterobacter aerogenes ATCC13048, Klebsiella pneumoniae KP55, Providencia stuartii NEA16 and Staphylococcus aureus MRSA3. 28-hydroxy-β-amyrin (8) significantly impaired the growth of Enterobacter aerogenes EA27, Klebsiella pneumoniae ATCC11296 and Staphylococcus aureus MRSA6; and oleanolic acid (9) strongly impaired the growth of Escherichia coli AG 102, Enterobacter aerogenes EA27 and Providencia stuartii PS2636. Diospyric acid (7) and 28-hydroxy-β-amyrin (8) induced perturbation of H⁺-ATPase pump and inhibition of the cellular ATP production. Moreover, at MIC/2 and MIC/4, compounds 7, 8, and 9 strongly improved the antibacterial activity of norfloxacin, ciprofloxacin and doxycycline with antibiotic-modulating factors ranging between 2 and 64.

Conclusion

The overall results of the current work demonstrate that diospyric acid (7), 28-hydroxy-β-amyrin (8) and oleanolic acid (9) are the major bioactive constituents of Donella welwitschia towards Gram-negative bacteria expressing MDR phenotypes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03673-3.

Potential Use of African Botanicals and Other Compounds in the Treatment of Methicillin-Resistant Staphylococcus aureus Infections

Infections caused by the group of Staphylococcus bacteria are commonly called Staph infections, and over 30 types of Staphylococcal bacteria exist with Staphylococcus aureus causing about 90% of the infections from the genus. Staphylococcus aureus (S. aureus) is a major cause of both hospital- and community-acquired infections with major concern arising from its strain of species that is resistant to many antibiotics. One of such strain is the Methicillin-resistant Staphylococcus aureus (MRSA) that has been described to be a resistance to methicillin drugs. Another is glycopeptides-resistant emerging from the increased use of glycopeptides drugs. This continuous emergence and spread of new resistant strains of S. aureus is a major challenge which makes the search for novel anti-resistant agents imperative. The development of vaccines from natural and synthetic products is some of the measures being proposed for the protection against the infections. Also, the development of monoclonal or polyclonal antibodies for passive immunization is sought for, and attentions with regard to arriving at successful trials have been directed back to medicinal plant research as an alternative. This review discusses the treatment strategies of MRSA, the antibacterial property of various medicinal plants, and the influence of their active compounds on methicillin-resistant S. aureus (MRSA), as well as to recommend the path to future research in this area.

Identification and Characterization of a Bacteriocin from the Newly Isolated Bacillus subtilis HD15 with Inhibitory Effects against Bacillus cereus

Natural antimicrobial substances are needed as alternatives to synthetic antimicrobials to protect against foodborne pathogens. In this study, a bacteriocin-producing bacterium, Bacillus subtilis HD15, was isolated from doenjang, a traditional Korean fermented soybean paste. We sequenced the complete genome of B. subtilis HD15. This genome size was 4,173,431 bp with a G + C content of of 43.58%, 4,305 genes, and 4,222 protein-coding genes with predicted functions, including a subtilosin A gene cluster. The bacteriocin was purified by ammonium sulfate precipitation, Diethylaminoethanol-Sepharose chromatography, and Sephacryl gel filtration, with 12.4-fold purification and 26.2% yield, respectively. The purified protein had a molecular weight of 3.6 kDa. The N-terminal amino acid sequence showed the highest similarity to Bacillus subtilis 168 subtilosin A (78%) but only 68% similarity to B. tequilensis subtilosin proteins, indicating that the antimicrobial substance isolated from B. subtilis HD15 is a novel bacteriocin related to subtilosin A. The purified protein from B. subtilis HD15 exhibited high antimicrobial activity against Listeria monocytogenes and Bacillus cereus. It showed stable activity in the range 0-70°C and pH 2-10 and was completely inhibited by protease, proteinase K, and pronase E treatment, suggesting that it is a proteinaceous substance. These findings support the potential industrial applications of the novel bacteriocin purified from B. subtilis HD15.

Antibacterial Screening of Isoespintanol, an Aromatic Monoterpene Isolated from Oxandra xylopioides Diels

The incidence of nosocomial infections, as well as the high mortality and drug resistance expressed by nosocomial pathogens, especially in immunocompromised patients, poses significant medical challenges. Currently, the efficacy of plant compounds with antimicrobial potential has been reported as a promising alternative therapy to traditional methods. Isoespintanol (ISO) is a monoterpene with high biological activity. Using the broth microdilution method, the antibacterial activity of ISO was examined in 90 clinical isolates, which included 14 different species: (Escherichia coli (38), Pseudomonas aeruginosa (12), Klebsiella pneumoniae (13), Acinetobacter baumannii (3), Proteus mirabilis (7), Staphylococcus epidermidis (3), Staphylococcus aureus (5), Enterococcus faecium (1), Enterococcus faecalis (1), Stenotrophomonas maltophilia (2), Citrobacter koseri (2), Serratia marcescens (1), Aeromonas hydrophila (1), and Providencia rettgeri (1). MIC90 minimum inhibitory concentration values ranged from 694.3 to 916.5 µg/mL and MIC50 values from 154.2 to 457.3 µg/mL. The eradication of mature biofilms in P. aeruginosa after 1 h of exposure to ISO was between 6.6 and 77.4%, being higher in all cases than the percentage of biofilm eradication in cells treated with ciprofloxacin, which was between 4.3 and 67.5%. ISO has antibacterial and antibiofilm potential against nosocomial bacteria and could serve as an adjuvant in the control of these pathogens.

Synergistic activity of pomegranate rind extract and Zn (II) against Candida albicans under planktonic and biofilm conditions, and a mechanistic insight based upon intracellular ROS induction

Candida albicans (C. albicans) is an opportunistic pathogen, which causes superficial infection and can lead to mortal systemic infections, especially in immunocompromised patients. The incidence of C. albicans infections is increasing and there are a limited number of antifungal drugs used in treatment. Therefore, there is an urgent need for new and alternative antifungal drugs. Pomegranate rind extract (PRE) is known for its broad-spectrum antimicrobial activities, including against C. albicans and recently, PRE and Zn (II) have been shown to induce synergistic antimicrobial activity against various microbes. In this study, the inhibitory activities of PRE, Zn (II) and PRE in combination with Zn (II) were evaluated against C. albicans. Antifungal activities of PRE and Zn (II) were evaluated using conventional microdilution methods and the interaction between these compounds was assessed by in vitro checkerboard and time kill assays in planktonic cultures. The anti-biofilm activities of PRE, Zn (II) and PRE in combination with Zn (II) were assessed using confocal laser scanning microscopy, with quantitative analysis of biofilm biomass and mean thickness analysed using COMSTAT2 analysis. In addition, antimicrobial interactions between PRE and Zn (II) were assayed in terms reactive oxygen species (ROS) production by C. albicans. PRE and Zn (II) showed a potent antifungal activity against C. albicans, with MIC values of 4 mg/mL and 1.8 mg/mL, respectively. PRE and Zn (II) in combination exerted a synergistic antifungal effect, as confirmed by the checkerboard and time kill assays. PRE, Zn (II) and PRE and Zn (II) in combination gave rise to significant reductions in biofilm biomass, although only PRE caused a significant reduction in mean biofilm thickness. The PRE and Zn (II) in combination caused the highest levels of ROS production by C. albicans, in both planktonic and biofilm forms. The induction of excess ROS accumulation in C. albicans may help explain the synergistic activity of PRE and Zn (II) in combination against C. albicans in both planktonic and biofilm forms. Moreover, the data support the potential of the PRE and Zn (II) combination as a novel potential anti-Candida therapeutic system.

Novel Polyhydroquinoline-Hydrazide-Linked Schiff's Base Derivatives: Multistep Synthesis, Antimicrobial, and Calcium-Channel-Blocking Activities

Polyhydroquinoline (PHQ) are the unsymmetrical Hantzsch derivatives of 1,4-dihydropyridines with several biological applications. In this work, twenty-five (3-27) new Schiff's base derivatives of polyhydroquinoline hydrazide were synthesized in excellent to good yields by a multi-component reaction. The structures of the synthesized products (1-27) were deduced with the help of spectroscopic techniques, such as 1H-, 13C -NMR, and HR-ESI-MS. The synthesized products (1-27) were tested for their antibacterial and in vitro calcium -channel-blocking (CCB) potentials using the agar-well diffusion method, and isolated rat aortic ring preparations, respectively. Among the series, sixteen compounds were found to inhibit the growth of Escherichia coli and Enterococcus faecalis. Among them, compound 17 was observed to be the most potent one at a dose 2 µg/mL, with an 18 mm zone of inhibition against both bacteria when it was compared with the standard drug amoxicillin. Eight compounds showed CCB activity of variable potency; in particular, compound 27 was more potent, with an EC50 value of 0.7 (0.3-1.1) µg/mL, indicating their CCB effect.

Bioactive Compounds from Elderberry: Extraction, Health Benefits, and Food Applications

Elderberries are appreciated for their antioxidant properties. Sambucus nigra L. is an extremely abundant plant in the wild flora of Romania, but it is underutilized. Elderberry is used in modern and traditional medicine due to the complex chemical composition of the fruit. The content of phenolic compounds is high (516–8974 mg/100 g DW), of which the most abundant are anthocyanins. Phenolic compounds are known for their beneficial effects on the body. Numerous studies have demonstrated the antioxidant capacity, antibacterial, antiviral, antidiabetic, and anticancer properties of the fruit. It is considered that most of the therapeutic properties of elderberries can be correlated with the antioxidant activity they have. S. nigra fruits are also used in the food industry. Some studies have shown that the therapeutic properties of elderberries can also be found in the products obtained from them. Therefore, this review aimed to describe the chemical composition of elderberries and products obtained from them, the positive effects on the body, and the methods by which the bioactive compounds can be extracted from the fruits and analyzed. This manuscript is useful for extraction optimization and characterization in order to valorize new functional foods, food supplements, and also in new pharmaceutical products.

Fusarium oxysporum infection-induced formation of agarwood (FOIFA): A rapid and efficient method for inducing the production of high quality agarwood

Agarwood, a non-wood product from the endangered Aquilaria and Gyrinops tress, is highly prized for its use in fragrances and medicines. The special formation process of agarwood is closely related to external injury and fungal infection. In this study, we demonstrate that infection of Aquilaria sinensis by Fusarium oxysporum, a soilborne fungus that causes vascular wilt diseases in diverse plants, induces agarwood formation. Based on these findings, an efficient method, termed F. oxysporum infection-induced formation of agarwood (FOIFA), was developed for the rapid production of quality agarwood. The agarwood formed in response to F. oxysporum infection was similar in structure and chemical composition to wild agarwood according to TLC (Thin-layer chromatography), HPLC (high performance liquid chromatography), and GC-MS (gas chromatography-mass spectrometry) analyses, except that the contents of alcohol-soluble extract, chromones, and essential oils (mainly sesquiterpenes) were higher in the formed agarwood.

Transcriptional and biochemical profiling of defense enzymes in Citrus sinensis during salicylic acid and cinnamon mediated suppression of green and blue mold

Green and blue mold of citrus are threatening diseases that continuously inflict economic post-harvest loss. The suppressive effect of salicylic (SA) and Cinnamomum verum (CV) on green and blue mold of sweet oranges was investigated in this study. Among five tested plant extracts methanolic extract of Cinnamon caused the highest colony growth inhibition of P. digitatum and P. italicum in an in vitro antifungal assay. The methanolic extract of Cinnamon in combination with SA showed the lowest disease incidence and severity of green and blue mold on citrus fruit without affecting the fruit quality. Transcriptional profiling of defense enzymes revealed that the polyphenol oxidase (PPO), phenylalanine ammonia-lyase (PAL), and peroxidase (POD) genes were upregulated in fruit treated with CV, SA, and their combination compared to the control. The treatment SA+CV caused the highest upsurge in PPO, POD, and PAL gene expression than the control. Furthermore, the biochemical quantification of PPO, POD and PAL also revealed a similar pattern of activity. The present findings unravel the fact that the escalation in the activity of tested defense enzymes is possibly associated with the reduced incidence of blue and green molds. In conclusion, the study unveils the promising suppressive potential of SA+CV against green and blue mold by regulating the expression of PPO, POD, and PAL genes. Therefore, these treatments can find a role as safer alternatives to chemicals in the management of post-harvest green and blue mold.

Influence of Altitudes and Development Stages on the Chemical Composition, Antioxidant, and Antimicrobial Capacity of the Wild Andean Blueberry (Vaccinium floribundum Kunth)

The chemical composition and biological capacities of berries depend on environmental parameters, maturity, and location. The Andean blueberry (Vaccinium floribundum Kunth), also known as mortiño, presents a unique combination of several phytochemicals, which play a synergistic role in its characterization as a functional food. We aimed to expose the possible variations that exist in the profile of the phenolic compounds as well as the antioxidant and antimicrobial capacity of the wild Andean blueberry with respect to three ripeness stages and two different altitudes. We found that polyphenols are the predominant compounds in the berry during the early ripeness stage and are the main bioactive compounds that give rise to the antioxidant capacity and inhibition effect on the growth of gram-positive and gram-negative bacteria. Moreover, the accumulation of ascorbic acid, free amino acids, and anthocyanins increases as the ripening process progresses, and they were the main bioactive compounds in the ripe berry. The latter compounds influence the production of the typical bluish or reddish coloration of ripe blueberries. In addition, it was determined that environmental conditions at high altitudes could have a positive influence in all cases. Overall, our data provide evidence regarding the high functional value of the wild Andean blueberry.

Phytochemical Variability, In Vitro and In Vivo Biological Investigations, and In Silico Antibacterial Mechanisms of Mentha piperita Essential Oils Collected from Two Different Regions in Morocco

The objective of this work is to explore the phytochemical profile of Mentha piperita essential oils (MPEO) collected from two different Moroccan regions using gas chromatography-mass spectrophotometer (GC-MS) and to investigate their antioxidant, anti-inflammatory, antidiabetic and, antimicrobial effects using in vivo and in vitro assays. The chemical constituent of MPEO from the Azrou zone is dominated by carvone (70.25%), while MPEO from the Ouazzane zone is rich in Menthol (43.32%) and Menthone (29.4%). MPEO from Ouezzane showed higher antioxidant activity than EO from Azrou. Nevertheless, EO from Ouezzane considerably inhibited 5-Lipoxygenase (IC50 = 11.64 ± 0.02 µg/mL) compared to EO from Azro (IC50 = 23.84 ± 0.03 µg/mL). Both EOs from Azrou and Ouazzane inhibited the α-amylase activity in vitro, with IC50 values of 131.62 ± 0.01 µg/mL and 91.64 ± 0.03 µg/mL, respectively. The EOs were also tested for minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The discdiffusion test revealed that MPEOs from both regions have significant antibacterial efficacy, and MPEOs from the north region showed the highest effect. The gram-positive bacteria were the most susceptible organisms. The MIC concentrations were in the range of 0.05 to 6.25 mg/mL, and the MBC concentrations were within 0.05-25.0 mg/mL. The MBC/MIC index indicated that MPEO has strong bactericidal effects.

Deciphering environmental factors and defense response of rice genotypes against sheath blight disease

Sheath blight (ShB) is one of the most serious diseases in rice, leading to severe yield losses globally. In our study, we evaluated a total of 63 rice genotypes for resistance against sheath blight disease by artificial inoculation over two seasons under field conditions and studied the weather parameters associated with disease incidence. Based on two years of testing, 23 genotypes were found moderately resistant, 38 were moderately susceptible, and 2 exhibited a susceptible reaction to sheath blight disease. Among the specific four genotypes (IC283139, IC283041, IC283038, and IC283023) of the moderately resistant group exhibited less disease reaction in comparison with check variety Tetep. Further, the correlation of percent disease index (PDI) with weather parameters revealed negative associations between PDI and maximum temperature, minimum temperature, low rainfall and the positive association with maximum relative humidity (RH) suggest that very low temperature or high precipitation might have a negative impact on pathogen establishment. In addition, the sheath blight-linked SSRs were assessed using distance and model-based approaches, results of both the models revealed that genotypes distinguished the resistant population from the susceptible one. From the output of two years of principal component analysis, two genotypes from each group of moderately resistant, moderately susceptible and susceptible were studied for their biochemical reaction against the sheath blight pathogen. The biochemical study revealed that the accumulation of defense and antioxidant enzymes, namely, polyphenol oxidase, peroxidase, total phenol, phenylalanine ammonia-lyase, catalase, and superoxide dismutase, were higher in moderately resistant genotypes, but was observed to be lower in moderately susceptible and susceptible genotypes. The statistical analysis revealed the enzyme activities (defense and antioxidant) exhibited a strong negative correlation with area under the disease progress curve (AUDPC) and influence of weather parameter RH. This demonstrates that the environment factor RH plays a major role in imparting the resistance mechanism by decreasing the enzymes activities and increasing PDI. This study found that the identified novel resistant genotype (IC283139) with purple stem base demonstrated improved resistance against sheath blight infection through a defense response and the use of antioxidant machinery.

Can polyphenolic surface modifications prevent fungal colonization of titanium dental implants?

Oral biofilms can be a major health problem causing infections and chronic inflammation of mucosal tissue. While much effort is put in the investigation of bacteria in biofilms, the role of fungi is often neglected, despite Candida albicans playing a key role in the formation of multispecies oral biofilms. With the rise of antibiotic resistance, new strategies to reduce microbial growth need to be found. Therefore, plant derived polyphenolic molecules have been suggested to reduce both adhesion and growth of pathogenic bacteria and fungi. In this study, we investigated the use of polyphenolic coatings to reduce adhesion and biofilm formation of C. albicans BWP17 on titanium implants. Tannic acid and pyrogallol coatings altered the hydrophobic and charge properties of titanium surfaces, and both compounds were gradually released as active molecules over time. Despite such effects, we found no significant inhibition on growth and biofilm formation of C. Albicans, indicating that the release of active molecules from the coatings did not reach relevant inhibitory concentrations. However, a potential antibiofilm effect was observed by the pH-dependent disassembly of the polyphenolic layer, which caused the biofilm to detach. Hence, further efforts are required to create tailored implant surfaces, which sustainably reduce microbial growth and adhesion.

Water-soluble saponins accumulate in drought-stressed switchgrass and may inhibit yeast growth during bioethanol production

BACKGROUND

Developing economically viable pathways to produce renewable energy has become an important research theme in recent years. Lignocellulosic biomass is a promising feedstock that can be converted into second-generation biofuels and bioproducts. Global warming has adversely affected climate change causing many environmental changes that have impacted earth surface temperature and rainfall patterns. Recent research has shown that environmental growth conditions altered the composition of drought-stressed switchgrass and directly influenced the extent of biomass conversion to fuels by completely inhibiting yeast growth during fermentation. Our goal in this project was to find a way to overcome the microbial inhibition and characterize specific compounds that led to this inhibition. Additionally, we also determined if these microbial inhibitors were plant-generated compounds, by-products of the pretreatment process, or a combination of both.

RESULTS

Switchgrass harvested in drought (2012) and non-drought (2010) years were pretreated using Ammonia Fiber Expansion (AFEX). Untreated and AFEX processed samples were then extracted using solvents (i.e., water, ethanol, and ethyl acetate) to selectively remove potential inhibitory compounds and determine whether pretreatment affects the inhibition. High solids loading enzymatic hydrolysis was performed on all samples, followed by fermentation using engineered Saccharomyces cerevisiae. Fermentation rate, cell growth, sugar consumption, and ethanol production were used to evaluate fermentation performance. We found that water extraction of drought-year switchgrass before AFEX pretreatment reduced the inhibition of yeast fermentation. The extracts were analyzed using liquid chromatography-mass spectrometry (LC-MS) to detect compounds enriched in the extracted fractions. Saponins, a class of plant-generated triterpene or steroidal glycosides, were found to be significantly more abundant in the water extracts from drought-year (inhibitory) switchgrass. The inhibitory nature of the saponins in switchgrass hydrolysate was validated by spiking commercially available saponin standard (protodioscin) in non-inhibitory switchgrass hydrolysate harvested in normal year.

CONCLUSIONS

Adding a water extraction step prior to AFEX-pretreatment of drought-stressed switchgrass effectively overcame inhibition of yeast growth during bioethanol production. Saponins appear to be generated by the plant as a response to drought as they were significantly more abundant in the drought-stressed switchgrass water extracts and may contribute toward yeast inhibition in drought-stressed switchgrass hydrolysates.

Chemical Composition, Antibacterial, Antifungal and Antidiabetic Activities of Ethanolic Extracts of Opuntia dillenii Fruits Collected from Morocco

Opuntia dillenii (Ker Gawl.) Haw. belongs to the Cactaceae family and is native to the arid and semi-arid regions of Mexico and the southern United States. O. dillenii are now used as medicinal plants in various countries. In this study, we investigated the chemical composition of ethanolic extracts obtained from seeds, juice, and peel of O. dillenii fruits collected from Morocco, and we evaluated their antibacterial, antifungal, and antidiabetic activities. Phytochemical screening revealed high quantities of polyphenols (193.73 ± 81.44 to 341.12 ± 78.90 gallic acid eq [g/100 g dry weight]) in the extracts. The major phenolic compounds determined by HPLC were gallic acid, vanillic acid, and syringic acid. Regarding flavonoids, quercetin 3-O-β-D-glucoside and kaempferol were the predominant molecules. Juice extracts showed weak to moderate antibacterial activity against the bacteria species Listeria monocytogenes, Escherichia coli, and Salmonella braenderup. All tested extracts displayed a significant inhibitory effect on α-glucosidase and α-amylase activities in vitro, with the peel extracts showing the greatest inhibitory effects. Together, these findings suggest that O. dillenii fruits are a promising source for the isolation of novel compounds with antibacterial or antidiabetic activities. For the most abundant phytochemicals identified in O. dillenii peel ethanolic extract, molecular docking simulations against human pancreatic α-amylase enzyme were performed. These indicated the presence of bioactive compounds in the extract with a better potential to decrease the enzyme activity than the commercial drug acarbose.

Chemical Composition and Antioxidant, Antimicrobial, and Anti-Inflammatory Properties of Origanum compactum Benth Essential Oils from Two Regions: In Vitro and In Vivo Evidence and In Silico Molecular Investigations

The purposes of this investigatory study were to determine the chemical composition of the essential oils (EOs) of Origanum compactum from two Moroccan regions (Boulemane and Taounate), as well as the evaluation of their biological effects. Determining EOs' chemical composition was performed by a gas chromatography-mass spectrophotometer (GC-MS). The antioxidant activity of EOs was evaluated using free radical scavenging ability (DPPH method), fluorescence recovery after photobleaching (FRAP), and lipid peroxidation inhibition assays. The anti-inflammatory effect was assessed in vitro using the 5-lipoxygenase (5-LOX) inhibition test and in vivo using the carrageenan-induced paw edema model. Finally, the antibacterial effect was evaluated against several strains using the disk-diffusion assay and the micro-dilution method. The chemical constituent of O. compactum EO (OCEO) from the Boulemane zone is dominated by carvacrol (45.80%), thymol (18.86%), and α-pinene (13.43%). However, OCEO from the Taounate zone is rich in 3-carene (19.56%), thymol (12.98%), and o-cymene (11.16%). OCEO from Taounate showed higher antioxidant activity than EO from Boulemane. Nevertheless, EO from Boulemane considerably inhibited 5-LOX (IC50 = 0.68 ± 0.02 µg/mL) compared to EO from Taounate (IC50 = 1.33 ± 0.01 µg/mL). A similar result was obtained for tyrosinase inhibition with Boulemane EO and Taounate EO, which gave IC50s of 27.51 ± 0.03 μg/mL and 41.83 ± 0.01 μg/mL, respectively. The in vivo anti-inflammatory test showed promising effects; both EOs inhibit and reduce inflammation in mice. For antibacterial activity, both EOs were found to be significantly active against all strains tested in the disk-diffusion test, but O. compactum EO from the Boulemane region showed the highest activity. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) for O. compactum EO from the Boulemane region ranged from 0.06 to 0.25% (v/v) and from 0.15 to 0.21% (v/v) for O. compactum from the Taounate region. The MBC/MIC index revealed that both EOs exhibited remarkable bactericidal effects.

Hyphaene thebaica (Areceaeae) as a Promising Functional Food: Extraction, Analytical Techniques, Bioactivity, Food, and Industrial Applications

Hyphaene thebaica, also known as doum, is a wild plant growing in Egypt, Sudan, and other African countries. It is usually used to prepare nutritive diets, tasty beverages, and other food products. This review aimed to highlight the phytochemical composition of the doum plant using NMR, GC–MS, HPLC, and UPLC/Qtof/MS. The reported active constituents are also described, with flavonoids, phenolic acids, and saponins being the most dominant components. Extraction methods, both conventional and non-conventional, and their existing parameters were summarized. The in vitro and in vivo studies on the extracts and active constituents were also reported. We focused on different applications of doum in functional food products, animal feeding systems, and pharmaceutical applications. Doum is considered a promising dietary and therapeutic candidate to be applied on a wider scale. Proteomic analysis of doum and clinical assessment are still lacking and warrant further investigations in the future.

Antifungal potential of isoespintanol extracted from Oxandra xylopioides diels (Annonaceae) against intrahospital isolations of Candida SPP

The aim of this study was to evaluate the antifungal activity of isoespintanol (ISO) extracted from Oxandra xylopioides Diels (Annonaceae) against clinical isolates of Candida spp. Isoespintanol was obtained from the petroleum benzine extract of the leaves and was identified by nuclear magnetic resonance (NMR) and mass spectrometry (MS). For antifungal activity experiments, the broth microdilution method was used. The results show an inhibitory effect against Candida spp., with minimum inhibitory concentration (MIC) values between 450.4-503.3 μg/mL. Furthermore, the inhibitory effect of ISO against fungal biofilms is highlighted, even in some cases, greater than the effect shown by amphotericin B (AFB) and in others, where AFB showed no effect. Assays with fluorescent staining with acridine orange (AO) and ethidium bromide (EB), transmission electron microscopy (TEM), Evans blue, measurement of extracellular pH and leakage of intracellular material, evidenced damage at the level of fungal membranes and general cell damage, when cells were exposed to ISO, compared to untreated cells. The results of this research, serve as the basis for future studies in the establishment of the mechanisms of antifungal action of ISO, which could serve as an adjunct in the treatment of infections by these yeasts.

Anti-quorum sensing and biofilm inhibitory effect of some medicinal plants against gram-negative bacterial pathogens: in vitro and in silico investigations

Multidrug resistance (MDR) in pathogenic bacteria have become a major clinical issue. Quorum sensing regulated bacterial virulence is a promising key drug target for MDR infections. Therefore, the aim of the present work was to assess the anti-quorum sensing properties of selected medicinal plants against bacterial pathogens as well in silico interaction of selected bioactive phytocompounds with QS and biofilm-associated proteins. Based on the ethnopharmacological usage, 18 plants were selected using methanolic extract against Chromobacterium violaceum 12472. The most active extract (Acacia nilotica) was fractionated in increasing polarity solvents (n-hexane, chloroform and ethyl acetate) and tested for anti-QS activity. The most active fraction i.e. ethyl acetate fraction was evaluated for their activity at sub-MICs against QS-associated virulence factors of Pseudomonas aeruginosa PAO1 and Serretia marcescens MTCC 97. Microtiter plate assay and light microscopy was used to determine inhibition of biofilm. Phytochemicals of the ethyl acetate fraction were analysed by GC/MS and LC/MS. Phytocompounds were docked with QS (LasI, LasR, CviR, and rhlR) and biofilm proteins (PilY1 and PilT) using Auto dock vina. The MIC of ethyl acetate fraction determined was 250, 500, and 1000 μg/ml against C. violaceum 12472, P. aeruginosa PAO1, and S. marcescens MTCC97 respectively. At sub-MICs QS regulated virulence factors production and inhibited biofilms broadly (more than 50 percent). GC/MS detected the major bioactive compound benzoic acid, 3,4,5-trihydroxy-, methyl ester (61.24 %) and LC-MS detected Retronecine for the first time in A. nilotica pods. In silico, dehydroabietic acid occupied the same cavity as its antagonist in the CviR ligand binding domain. Also, betulin and epicatechin gallate interact with biofilm proteins PilY1 and PilT, preventing biofilm formation. The findings suggest that the phytochemicals of A. nilotica pod could be exploited as an anti-QS agent against Gram-negative pathogens. To discover therapeutic efficacy of standardised bioactive extract/phytochemicals must be tested under in vivo condition.