Lowest Minimum Inhibitory Concentration Value Research Articles

Development of Cyclometalated Iridium(III) Complexes of 2-Phenylbenzimidazole and Bipyridine Ligands for Selective Elimination of Gram-Positive Bacteria.

Herein, we have reported a series of cationic aggregation-induced emission (AIE) active iridium(III) complexes (Ir1-Ir5) of the type [Ir(C^N)2(N^N)]Cl, wherein C^N is a cyclometalating 2-phenylbenzimidazole ligand with varying alkyl chain lengths and N^N is a 2,2'-bipyridine ligand attached to bis-polyethylene glycol chains, for the treatment of bacterial infections. The AIE phenomenon of the complexes leveraged for detecting bacteria by fluorescence microscopy imaging that displayed a strong red emission in Gram-positive bacteria. The antibacterial activity of the complexes assessed against Gram-positive methicillin-sensitive S. aureus, methicillin-resistant S. aureus, E.faecium and E.faecalis and Gram-negative E. coli and P.aeruginosa bacteria of clinical interest. The complexes Ir2-Ir4 exerted potent antibacterial activity towards Gram-positive strains with low minimum inhibitory concentrations (MICs) values in the range of 1-9 μM, which is comparable to clinically approved antibiotic vancomycin. In contrast, these complexes were found to be inactive towards Gram-negative bacterial strains (MICs > 100 µM). The mechanism of antibacterial activity of the complexes implies that ROS generation, membrane depolarization and rupture are responsible for bacterial cell death. Further, the complexes Ir1-Ir3 were found to be low-toxic against human red blood cells and human embryonic kidney (HEK293) cells, indicating their potential for use as antibacterial agents.

Antimicrobial effects of eugenol-based micro- vs. nano-emulsions: Evaluation of shelf-life enhancement in Sikhye

This study investigated the antibacterial properties of micro-emulsions (MEs) and nano-emulsions (NEs) containing eugenol and rice bran oil to enhance the shelf life of Sikhye, a traditional Korean rice beverage. The emulsions were evaluated using the agar disk diffusion method and minimum inhibitory concentration (MIC) tests against Escherichia coli, Bacillus cereus, and Staphylococcus aureus. The results demonstrated that MEs exhibited larger inhibition zones and lower MIC values than NEs, indicating superior antibacterial activity. The application of these emulsions in Sikhye revealed that a higher eugenol content and larger droplet size effectively inhibited bacterial growth. The study also found that, while rice bran oil contributed to physical stability, it did not enhance the antimicrobial effect and, in some cases, promoted bacterial growth. Overall, these findings suggest that eugenol-rich MEs could serve as effective natural preservatives, improving the safety and shelf life of Sikhye and potentially other food products.

Extract from Psidium guineense Sw leaves: An alternative against resistant strains of Staphylococcus aureus

Psidium guineense SW., commonly known as sour guava, is used in traditional medicine to address diverse health issues, such as inflammation, infections, and gastrointestinal disorders. Although previous research has highlighted the antimicrobial properties of the root extract and the antioxidant potential of its fruits, information regarding the activities associated with the leaf extract is lacking. The aim of the study was to use the traditional knowledge of the biological properties of P. guineense and investigate its antimicrobial activity, mechanism of action, synergistic effects, and antivirulence activity against Staphylococcus aureus. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were determined for S. aureus, including antibiotic-resistant isolates. The synergy between the extract and antibiotics was evaluated. A growth curve was constructed for S. aureus treated with the extract. The anti-hemolytic activity was assessed by inhibiting hemolysis in human blood, and the inhibition of staphyloxanthin (STX) was examined. The extract effectively inhibited all strains with MIC and MBC values ranging from 256 to 512 µg/mL and 512 to 1024 µg/mL, respectively. Antimicrobial synergy experiments demonstrated the enhanced effectiveness of antibiotics, especially ciprofloxacin, when combined with the P. guineense extract, especially with ciprofloxacin, resulting in complete synergy against all S. aureus strains. In growth curve tests, the extract inhibited growth at MIC of 256 µg/mL within 8 h and significantly delayed it at MIC/2 (128 µg/mL) within 12 h. In antivirulence tests, the extract effectively reduced hemolysis and STX production by S. aureus at MIC and MIC/2, indicating its potential as an antimicrobial agent with antivirulence properties. The extract effectively inhibited S. aureus, including drug-resistant strains with low MIC and MBC values, exhibiting strong antimicrobial and synergistic properties with antibiotics. also In addition, the extract accelerated recovery by limiting bacterial growth and exhibiting antivirulence capabilities, reducing the severe symptoms of S. aureus infections.

Ethanolic cashew leaf extract: Antifungal activity and its application for shelf-life extension of dried salted tilapia fillets.

Ethanolic cashew leaf extract (ECLE) is rich in phenolic compounds with diverse bioactivities and can serve as a safe natural preservative. This study evaluated the antifungal activity and application of ECLE for shelf-life extension of dried salted tilapia fillets. Several extraction methods, antifungal activity, and application of ECLE in dried salted tilapia fillets were investigated. Ultrasonication followed by the Soxhlet extraction resulted in the highest yield (26.78%), total phenolic content (TPC), and total flavonoid content (TFC) (p<0.05). Conversely, the Soxhlet extraction method rendered lower yield (14.35%), TPC, and TFC (p<0.05). NaCl at high concentrations decreased both TPC and TFC in all ECLE samples, demonstrating the decomposition of those compounds induced by NaCl. ECLE obtained via the Soxhlet extraction method exhibited lower minimum inhibitory concentration (MIC) and minimum fungicidal concentration values than those prepared using other extraction methods. Thus, the former showed higher efficacy in inhibiting fungal growth and reducing mycelium growth than others (p<0.05), despite being less effective than potassium sorbate. At 4MIC, ECLE inhibited mycelium growth (56.83%-78.66%) and spore germination (87.5%-100%) after 72h and 10-16h of treatment, respectively. ECLE (4MIC) could inhibit the toxin production of fungi. For the challenge test, in which ECLE at 400 and 600mg/kg was added to dried salted tilapia fillet inoculated with Aspergillus flavus, fungal growth was retarded over 9 days of storage at 25±2°C (room temperature). Thus, ECEL could act as a natural food preservative to prevent fungal contamination. Toxin from fungi could be avoided, and the quality of dried salted fish was maintained. PRACTICAL APPLICATION: Cashew leaf extract rich in polyphenols can inhibit fungal proliferation, reduce mycelium expansion, prevent spore germination, and limit aflatoxin production. The extract canenhance the safety of dried salted fish, especially when contaminated with Aspergillus flavus in the humid atmosphere (80% relative humidity), particularly for small and medium enterprises. Nevertheless, this extract can also be applied in the fish processing industry, in which the synthetic antifungal agent could be replaced by the natural additive.

Recent increase in Candida auris frequency in the SENTRY surveillance program: antifungal activity and genotypic characterization.

We observed an increase in the frequency of Candida auris among invasive candidiasis isolates in the 2022 SENTRY Antifungal Surveillance Program compared to prior years: ≤0.1% before 2018, 0.4%-0.6% from 2018 to 2021, and 1.6% in 2022. C. auris isolates were collected in seven countries, but 28 (35.9%) isolates were recovered in the USA (five states; more common in New York, Texas, and New Jersey) and 26 (33.3%) in Panama. Greece and Turkey had 12 and 9 isolates, respectively. Overall, 82.1% of the isolates were resistant to fluconazole; 17.9% were resistant to amphotericin B; and 1.3% were resistant to caspofungin, anidulafungin, or micafungin (Centers for Disease Control and Prevention tentative resistance breakpoints). Rezafungin inhibited 96.2% of the isolates (Clinical and Laboratory Standards Institute susceptibility breakpoint). Pandrug resistance was not observed, but 17.9% of the isolates were resistant to fluconazole and amphotericin B. South Asian (Clade I) isolates were most common (n = 40, 51.3%); of these, 97.5% were resistant to fluconazole and 30.0% were resistant to amphotericin B. Thirty (38.5%) isolates belonged to the South American region (Clade IV), and 56.7% of those were resistant to fluconazole and 6.7% to amphotericin B. Seven isolates belonged to the South African Clade III and one to East Asian Clade II. Erg11 (Y132F, K143R, and F126L) and MRR1 (N647T) alterations were detected. One isolate that was resistant to all echinocandins carried an FKS R1354G alteration. Two isolates displayed elevated rezafungin minimum inhibitory concentration (MIC) values but low MIC values against other echinocandins and no FKS alterations. As C. auris is spreading globally, monitoring this species is prudent.

SPECIES IDENTIFICATION AND IN VITRO ANTIFUNGAL SUSCEPTIBILITY TESTING OF ASPERGILLUS ISOLATED FROM VARIOUS CLINICAL SAMPLES

Objectives: Aspergillus is ubiquitous mold species present in environment in the form of spores. Infection due to Aspergillus is uncommon in immunocompetent individuals unless they possess any abnormality or have undergone any treatment with corticosteroids. In immunocompromised individuals, infection by this fungus is common among people with prolonged neutropenia, transplants, and human immunodeficiency virus infection. The symptoms are diverse, ranging from allergic reactions to invasive aspergillosis and life-threatening complications. The aim of this study is to isolate and identify Aspergillus species obtained from various clinical specimens and perform antifungal susceptibility testing (AFST). Methods: A total of 200 isolates in which positive direct microscopic findings correlated well with culture growth for Aspergillus were included. Antifungal susceptibility was performed by micro broth dilution technique according to clinical laboratory standard institute M38-A2 guidelines. Results: Aspergillus flavus was found to be predominant species followed by Aspergillus fumigatus. AFST was performed, where all Aspergillus strains exhibited low minimum inhibitory concentration (MIC) and minimum effective concentration (MEC) values for most of antifungal drugs tested except for one strain of A. flavus, which exhibited high MIC for voriconazole and high MEC for caspofungin. Conclusion: Polyenes, azoles, and echinocandin resistance are emerging in many parts of the world. Therefore, continued application of AFST combined with morphological characterization for species identification is critical in detecting the emergence of resistance among various Aspergillus species to reduce mortality, morbidity, and overcome treatment failure.

Synergistic effects of Psidium guajava and procaine penicillin on MRSA, MSSA and E. faecalis

Background: Antibiotic resistance is a significant public health challenge, exacerbated by resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA).Aim: This study investigates the synergistic antibacterial effects of Psidium guajava aqueous extract combined with procaine penicillin against MRSA, methicillin-sensitive S. aureus (MSSA) and Enterococcus faecalis.Setting: In-vitro study conducted under controlled laboratory settings at the Mangosuthu University of Technology, Department of Biomedical Sciences, Kwa-Zulu Natal, South Africa.Methods: Psidium guajava leaves were collected and prepared according to the German Homeopathic Pharmacopoeia, while procaine penicillin was diluted for testing. The combination treatment was evaluated using the Kirby–Bauer Antimicrobial Sensitivity Test and Minimum Inhibitory Concentration (MIC) assays.Results: Results showed that the combination of P. guajava extract and procaine penicillin significantly enhanced the antibacterial activity against MRSA, as evidenced by larger zones of inhibition and lower MIC values compared to P. guajava extract and procaine penicillin on their own. However, no significant difference was observed against MSSA and E. faecalis.Conclusion: The findings suggest that P. guajava extract could potentiate the efficacy of procaine penicillin against MRSA, providing a potential alternative strategy to combat antibiotic-resistant bacteria.Contribution: The study revealed that P. guajava aqueous extract enhances the antibacterial efficacy of procaine penicillin specifically against MRSA, suggesting a potential alternative treatment strategy for antibiotic-resistant infections, validated through robust methods and highlighting the need for further research to understand the mechanisms and clinical applications.

Antibacterial synergistic effect of sea cucumber extract and kelulut honey combination

Natural products remain one of the major sources of new drug molecules today. The combination of sea cucumber extract with stingless bee honey holds great potential for health supplement. However, the specific results of the combination have yet to be determined. In this study, the antibacterial activity of kelulut honey and Phyllophorus spiculata sea cucumber extract samples individually and in combination were assessed with disk-diffusion assays and broth dilution method. Most of the samples exhibit small or absence of inhibitory activity using disk-diffusion assay method. Only kelulut honey sample with 100% concentration has a positive antagonism effect against Escherichia coli and Staphylococcus epidermidis. For the broth dilution method, Gram-positive bacteria were found to be more susceptible as compared to Gram-negative bacteria species, with lower minimum inhibitory concentration (MIC) value of kelulut honey, sea cucumber or combination sample. The growth of gram-positive S. epidermidis is inhibited by sea cucumber extract at MIC value of 0.031 mg/mL, kelulut honey at MIC value of 0.063 mg/ mL and combination sample at MIC value of 0.063 mg/mL, all of which are of lower MIC value as compared to E. coli inhibition. The absorbance at optical density (OD) 600nm wavelength was also measured to monitor the growth of bacteria in solution. From the results, broth dilution proves to be a more effective method to assess the antibacterial activity in the combination samples. Two combinations showed the best antibacterial synergy (OD600 value of 0.000) against both Gram-positive and Gram-negative bacteria, which were (1) ½ sea cucumber: ½ kelulut honey combination and (2) ¾ sea cucumber: ¼ kelulut honey combination. This preliminary evidence on their antibacterial synergistic activities is promising and shows possible commercialization potential.

Jellein-I-conjugated gold nanoparticles: Insights into the antibacterial, antibiofilm activities against MRSA, and anticancer properties

Antimicrobial peptides (AMPs) and their conjugation with nanoparticles hold promise for targeting Methicillin-resistant Staphylococcus aureus (MRSA). In this study, Jellein-I peptide, with a cysteine at the C-terminus, was conjugated to gold nanoparticles (GNPs) to enhance its antibacterial, antibiofilm, and anticancer activities. The GNPs were synthesized and then conjugated to Jellein-I, forming Jellein-I-Cys-GNPs. The nanoparticles were characterized using UV–visible spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), and Fourier transform infrared (FTIR) spectroscopy. UV–visible spectroscopy, DLS, and TEM confirmed the formation of GNPs with an average size of 5.5 nm. The UV–visible spectroscopy and FTIR results indicated the presence of peptide functional groups on the surface of the GNPs. To assess antibacterial activity, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays were performed against MRSA strains. The conjugated Jellein-I exhibited lower MIC and MBC values (94 μM) compared to the free peptide (512 μM) against both clinical and standard MRSA strains. Additionally, GNP-conjugated Jellein-I demonstrated antibiofilm activity, inhibiting and removing biofilms while reducing metabolic activity by more than 82 %, 44 %, and 72 %, respectively. Cell viability studies on rat dermal fibroblast (RDF) cells showed over 80 % viability across all treatment concentrations. Furthermore, a clonogenic assay on the metastatic melanoma cell line (A375) demonstrated that GNP-conjugated Jellein-I had significantly better anticancer effects than the free peptide, even at a concentration as low as 9 μM. Our findings suggest that the conjugation of Jellein-I-Cys to GNPs could be a promising formulation for enhancing the antibacterial, antibiofilm, and anticancer activities of peptides. Further in vivo studies may establish this new nanoformulation as a potential therapeutic candidate for MRSA infections and cancer treatment.

First Confirmed Description of Acremonium egyptiacum from Greece and Molecular Identification of Acremonium and Acremonium-like Clinical Isolates.

Acremonium and the recently separated acremonium-like genera, such as Sarocladium, are emerging causes of opportunistic disease in humans, mainly post-traumatic infections in immunocompetent hosts, but also invasive infections in immunocompromised patients, such as those undergoing transplantation. Acremonium egyptiacum has emerged as the major pathogenic Acremonium species in humans, implicated mainly in nail but also in disseminated and organ specific infections. In this first study of acremonium-like clinical isolates in Greece, 34 isolates were identified and typed by sequencing the internal transcribed spacer, and their antifungal susceptibility was determined by a modified CLSI standard M38 3rd Edition method for filamentous fungi. A. egyptiacum was the primary species (18 isolates) followed by Sarocladium kiliense (8), Acremonium charticola, Gliomastix polychroma, Proxiovicillium blochii, Sarocladium terricola, Sarocladium zeae, and Stanjemonium dichromosporum (all with one isolate). Two isolates, each with a novel ITS sequence, possibly represent undescribed species with an affinity to Emericellopsis. All three A. egyptiacum ITS barcode types described to date were identified, with 3 being the major type. Flutrimazole, lanoconazole, and luliconazole presented the lower minimum inhibitory concentration (MIC) values against A. egyptiacum, with a geometric mean (GM) MIC of 2.50, 1.92, and 1.57 μg/mL, respectively. Amphotericin B, itraconazole, posaconazole, voriconazole, terbinafine, amorolfine, and griseofulvin MICs were overall high (GM 12.79-29.49 μg/mL). An analysis of variance performed on absolute values showed that flutrimazole, lanoconazole, and luliconazole were equivalent and notably lower than those of all the other drugs tested against A. egyptiacum. Antifungal susceptibility of the three different A. egyptiacum genotypes was homogeneous. Overall, the high MICs recorded for all systemically administered drugs, and for some topical antifungals against the tested A. egyptiacum and other acremonium-like clinical isolates, justify the routine susceptibility testing of clinical isolates.

Evaluation of Antibacterial Activities of Clove Bud Oil and Extract on Bacterial Isolates from Dental Caries

Dental caries remains one of the most prevalent oral health issues worldwide, primarily caused by bacterial activity w ithin the oral cavity. This study investigates the antibacterial activities of clove oil bud against bacteria associated with dental caries. The clove buds were collected, identified, and processed for ethanol extraction of bioactive compounds. Also, 30 samples of dental caries were obtained using swab sticks and cultured on nutrient agar, MacConkey agar, and Mannitol salt agar, then incubated for 24 hours and identified using biochemical tests and molecular analysis. Qualitative and quantitative phytochemical analysis confirmed the presence of alkaloids (5.033%), saponins (3.50%), flavonoids (0.407%), phenols (0.4545%), tannins (5.227%), and glycosides (2.1285%) in the ethanol extract, while the clove oil contained saponins (8.70%) and a small amount of glycosides (0.0375%). The extracted compounds underwent Gas Chromatography-Mass Spectrometry (GC-MS) analysis, which identified key constituents such as eugenol, Caryophyllene oxide, and 9,12-Octadecadienoic acid. The characterization of the clove oil revealed a density of 0.86 g/cm³, viscosity of 113.59 mm²/s, refractive index of ≥36% Brix, saponification value of 39.19 mg KOH, iodine value of 21.488 g/ml, peroxide value of 13.4 mEq/kg, and a free fatty acid content of 1.37%. Biochemical tests on the bacterial isolates from dental caries samples identified several species, including Actinomyces spp., Streptococcus spp., Lactococcus spp., Lacticaseibacillus paracasei, Staphylococcus aureus strain CIB, Bifidobacterium spp., Veillonella spp., and Bacillus subtilis. Antimicrobial activity assay shows that clove oil exhibited significant inhibition of microbial growth at higher concentrations: B.subtilis had inhibition zones of 12 mm at 100 mg/ml, 6 mm at 50 mg/ml, and 2 mm at 25 mg/ml. Similarly, Lacticaseibacillus agile 1365 showed inhibition zones of 14 mm at 100 mg/ml, 8 mm at 50 mg/ml, and 3 mm at 25 mg/ml. S.aureus strain B3A22 had inhibition zones of 10 mm at 100 mg/ml and 6 mm at 50 mg/ml. In contrast, L. paracasei showed minimal inhibition, indicating lower susceptibility to clove oil. On the other hand, the result also illustrates that clove extract was more effective at lower concentrations compared to clove oil. B.subtilis had inhibition zones of 14 mm at 100 mg/ml, 8 mm at 50 mg/ml, and 5 mm at 25 mg/ml. L.paracasei demonstrated inhibition zones of 16 mm at 100 mg/ml, 11 mm at 50 mg/ml, and 8 mm at 25 mg/ml. S.aureus strain B3A22 had inhibition zones of 10 mm at 100 mg/ml and 6 mm at 50 mg/ml. The Minimum Inhibitory Concentration (MIC) of clove oil was found to be 25 mg/ml for B.subtilis, 100 mg/ml for L.paracasei, 25 mg/ml for L.agile 1365, and 25 mg/ml for both S.aureus strain CIB and strain B3A22 respectively. In comparison, clove extract demonstrated lower MIC values: 12.5 mg/ml for B.subtilis, 12.5 mg/ml for L.paracasei, 12.5 mg/ml for L.agile 1365, 25 mg/ml for S.aureus strain CIB, and 25 mg/ml for S.aureus strain B3A22. The Minimum Bactericidal Concentration (MBC) of clove oil was 50 mg/ml for B.subtilis, for L.paracasei, 25 mg/ml for L.agile 1365, 50 mg/ml for S.aureus strain CIB, and 100 mg/ml for S.aureus strain B3A22. In contrast, clove extract showed an MBC of 25 mg/ml for B.subtilis, 50 mg/ml for L.paracasei, 25 mg/ml for L.agile 1365, 50 mg/ml for S.aureus strain CIB, and 25 mg/ml for S.aureus strain B3A22. These results underscore the significant antibacterial activity of clove extract, particularly due to its higher potency at lower concentrations compared to clove oil, supporting its potential use in developing alternative treatments for dental caries.

Phosphorus-Nitrogen Compounds: Part 76. Design and Syntheses of Dispiro- and Trispiro(N/N)cyclotriphosphazenes: Conformational and Structural Analyses, Chirality, Electrochemical, Dye-Sensitized Solar Cells, and Bioactivity Studies.

The reactions of monospirocyclotriphosphazenes (1 and 2) with N-methyl-1,3-diaminopropane gave unsymmetrical cis-(3 and 5) and trans-(4 and 6) dispirocyclotriphosphazenes. Trans-cis-trans (tct) (7 and 11), cis-cis-cis (ccc) (8 and 12), trans-trans-cis (ttc) (9 and 13), and cis-trans-trans (ctt) (14) trispirocyclotriphosphazenes were obtained from the reactions of 3 and 5 and 4 and 6 with N-methyl-1,3-diaminopropane. cis-Dispirocyclotriphosphazenes (3 and 5) exist as "pseudomesoracemates", while trans-dispirocyclotriphosphazenes (4 and 6) are in "racemates". The existences of cis-3 and trans-4 as "pseudomesoracemate" and "racemate" were confirmed by 31P NMR spectra recorded by the addition of "chiral solvating agent (CSA)". X-ray crystallography proved that the absolute configurations of each enantiomer of cis-5 and trans-6 are SS' and RS'. Trispirocyclotriphosphazenes tct, ttc, ccc, and ctt exist as racemates, pseudomesoracemate, and meso forms. Furthermore, Hirshfeld surface analysis of the crystal structures of cis-5 and trans-6 revealed that the most significant contribution to crystal packing comes from H···H (58.2 and 57.6%, respectively). An oxidation-reduction wave was detected in the reversible cyclic voltammograms of the phosphazenes. The highest power conversion efficiency in dye-sensitized solar cell studies was obtained with cis-5. Additionally, trans-6 exhibited the lowest minimal inhibitory concentration value (78.1 μM) against Candida tropicalis, and it was observed to cleave pBR322 plasmid DNA.

Two Novel Hydrate Salts of Norfloxacin with Phenolic Acids and Their Physicochemical Properties.

Norfloxacin (NORF) is a broad-spectrum quinolone that is widely utilized for the treatment of various bacterial infections and is considered one of the most commonly used fluoroquinolone antibiotics. However, NORF's clinical utility is limited by its poor water solubility and relatively low oral bioavailability. This study presents an optimization and synergistic enhancement approach through salt/co-crystal, aiming to maximize the biopharmaceutical properties of NORF with the use of phenolic acid. Following this strategy, two new hydrate salts of NORF with phenolic acid, namely, NORF-3,5-DBA hydrate (salt 1) and NORF-VA hydrate (salt 2), were prepared and systematically confirmed. Two hydrate salts were produced by means of the slow evaporation crystallization method, and the structures were determined through single-crystal X-ray diffraction (SCXRD). Additionally, powder X-ray diffraction (PXRD), Fourier-transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and high-performance liquid chromatography (HPLC) were applied to analyze the features of the two salts. The experimental results indicated that the formation of the two salts could enhance the solubility and improve the release behavior of NORF. Interestingly, the physicochemical properties of NORF were significantly improved as a result, leading to an enhancement in its antibacterial activity. This was demonstrated by the enhanced inhibition of bacterial strains and the lower minimum inhibitory concentration values.

Exploring Cynara cardunculus L. by-products potential: Antioxidant and antimicrobial properties

Cynara cardunculus L. (cardoon), a perennial crop indigenous to the Mediterranean region, has gained recognition for its remarkable resilience to diverse weather conditions and its multifaceted applications across various industries, which includes the use of the flower as a vegetable rennet to produce some cheeses, as a source of biomass for energy, or its seed oil for human consumption, biodiesel, and animal feed. In some applications (e.g. biomass or seed production), when crop is harvested at the end of the growth cycle, the leaves remain as the main by-products, along with the flowers. In the context of a circular economy, the aim of this work was to undergone studies to determinate their biological properties (antioxidant and antimicrobial). Methanolic and ethanolic extracts of C. cardunculus L. (globe artichoke var. scolymus (L.) Fiori) and cultivated cardoon (var. altilis DC.)) leaves and flowers were characterised in terms of their polyphenol profile (total phenolic content (TPC), total flavonoid compounds (TFC), and ultra-high performance liquid chromatography coupled with time-of-flight mass spectrometry (UHPLC-ToF-MS)), antioxidant capacity (free radical DPPH inhibition system, β-carotene bleaching assay), and antimicrobial capacity (minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), antifungal). In addition, the cultivated cardoon leaves extracts were assessed before and after they were dried in an oven with forced air circulation to evaluate if this treatment affected their bioactive profile. Chlorogenic acid, apigenin, and luteolin were the most quantified of a total of sixteen compounds identified by UHPLC-ToF-MS. Cultivated cardoon dry leaf extract presented the best antioxidant capacity for both methanolic (EC50 = 0.8 mg/mL, antioxidant activity coefficient (AAC) = 279.67) and ethanolic (EC50 = 2.1 mg/mL, AAC = 448.06) extracts, compared to the cardoon flower extracts and the globe artichoke leaf extracts. Dried cultivated cardoon leaf extracts presented higher antioxidant capacity than fresh cultivated cardoon leaf extracts, but a greater number of polyphenolic compounds were identified in fresh cultivated cardoon leaf extract. The Gram-positive bacteria were more sensitive to the activity of both ethanolic and methanolic extracts than the Gram-negative and cultivated cardoon dry leaf ethanolic extract presented lower MIC and MBC values (125–2000 µg/mL) for most of the tested microorganisms, thus showing higher antimicrobial activity. As for the cultivated cardoon leaf extracts, the dried leaf extracts exhibited better antimicrobial activity, with lower MIC values, than the fresh leaf extracts. The extracts only demonstrated a slight inhibition against the fungi Aspergillus fumigatus. In conclusion, studies performed indicate that dried leaves maintain their biological activities compared to fresh leaves, and that flowers present significant biological activity which suggests the great potential of the by-products of this crop as a source of active compounds in different industrial applications (e.g. food industry).

Antimicrobial activity evaluation of combinations of essential oils, thymol and R-limonene against food-borne pathogens and spoilage agents

The application of essential oils has been shown to be an effective and sustainable alternative against the multiplication of spoilage and pathogenic microorganisms in food. The aim of this work was to study the antimicrobial activity effect of Cerrado Rosemary (Baccharis dracunculifolia DC.), Pepper Rosemary (Lippia sidoides Cham.), Mandarin (Citrus nobilis Lour.), Mexican Lime (Citrus aurantifolia Swingle) essential oils, and the thymol and R-limonene compounds against strains of Penicillium expansum, Pichia kudriavzevii, Salmonella Thypimurium and Staphylococcus aureus. The essential oils were characterized in terms of their chemical composition, the Minimum Inhibitory Concentration, and Minimum Bactericidal and Fungicidal Concentration; using the microdilution method in 96-well plates. In addition, effects from mixtures of the essential oils, and the isolated compounds in sub-inhibitory concentrations were performed. The Pepper Rosemary essential oil and thymol, separately, showed the lowest Minimum Inhibitory Concentration values against all the microorganisms evaluated, with the lowest ranging from 0.03 to 1.25 mg. mL−1 for P. expansum and 0.31–1.25 mg. mL−1 for S. Thypimurium. Mandarin and Mexican lime, have an enhanced antimicrobial effect when used in mixture. The R-limonene compound showed a synergistic additive effect when combined with the essential oils, against S. aureus strains only. The application of thymol and Lippia was able to reduce growth by 3 log10 for S. aureus and S. Typhimurium in 24 h. Therefore, the Pepper Rosemary essential oil, applied freely or in combination with the thymol compound, has greater potential for use as an antifungal and bactericidal agent, against the microorganisms evaluated.

Exploring Bioactive Compounds in Prosopis juliflora Extracts Through Comparative LC–MS Analysis

ABSTRACTThe current study was carried out to assess the alkaloid‐enriched constituents of Prosopis juliflora (Fabaceae) against bacterial blight of pomegranate. Utilising plant extracts for disease management offers an eco‐friendly approach. In vitro assessment of the minimum inhibitory concentration (MIC) for alkaloid‐enriched fractions from the leaves and inflorescence of P. juliflora revealed a 14 mm zone of inhibition, with the lowest MIC value being 30 mg/mL. Untargeted metabolomics analysis of alkaloid‐rich fractions (ARF) from four different tissues of P. juliflora, subjected to LC–MS for alkaloid identification, detected a total of 1489 peaks in positive mode and 240 peaks in negative mode. The highest peaks were detected in the leaves, where 47 metabolites and 9 alkaloids were identified. Ellipticine and ormosanine were found in relatively high concentrations across all four tissues, as indicated by their peak areas. The inflorescence had significantly high concentrations of sparteine, solanidine‐I and puberanidine compared with other parts. Additionally, acetylsolanine was more abundant in the inflorescence, while solasodine‐I was more prevalent in the leaves. A substantial amount of strictosidine was also found in the inflorescence.

Comprehensive phytochemical profiling and biological activities of Hodgsonia heteroclita subsp. indochinensis seed extracts

Hodgsonia heteroclita subsp. indochinensis, a member of the Cucurbitaceae family, is utilized in traditional medicinal remedies based on indigenous wisdom. This study aimed to comprehensively identify and analyze the bioactive phytoconstituents within H. heteroclita subsp. indochinensis seeds. Seeds were sequentially extracted with n-hexane, ethyl acetate, and methanol. Liquid chromatography-mass spectrometry analysis detected ferulic acid, salicylic acid, cucurbitacin E, stigmasterol glucoside, and β-sitosterol glucoside in all extracts. The total phenolic content in the HH(S)-EtOAc and HH(S)-MeOH was 14.22 ± 1.58 and 12.98 ± 1.03 mg gallic acid equivalent/g, respectively. Consequently, the HH(S)-EtOAc demonstrated antioxidant activity with an IC50 of 1.10 ± 0.28 mg/mL, while the HH(S)-MeOH displayed strong antioxidant potential with an IC50 of 0.04 ± 0.00 mg/mL according to an ABTS assay. Antibacterial evaluations of both the HH(S)-hexane and HH(S)-EtOAc revealed significant activity against Staphylococcus aureus (zone of inhibition (ZOI): 13.67 ± 2.31 and 11.67 ± 1.53 mm, respectively) but limited activity against Escherichia coli (ZOI: 7.33 ± 0.58 and 7.67 ± 0.58 mm, respectively). Additionally, the extracts exhibited low minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values, ranging from 62.50 to 250 mg/mL. The antiproliferative activity of seed extracts was assessed against two breast cancer cell lines (MCF-7 and MDA-MB-231), normal breast cells (MCF10A), and human embryonic kidney (HEK) 293T cells, through MTT and clonogenic assays. The results revealed IC50 values exceeding 400 μg/mL, indicating that the extracts are safe. Furthermore, all seed extracts (50 μg/mL) exhibited potent anti-inflammatory activity, evident by their substantial inhibition of nitric oxide production (p < 0.001) and inducible nitric oxide synthase (iNOS) gene expression (p < 0.05) in LPS-induced RAW264.7. These findings demonstrate the potential for H. heteroclita subsp. indochinensis seed extracts in the development of functional foods, nutraceuticals, and dietary supplements due to their diverse bioactive compounds and substantial biological activities, particularly their anti-inflammatory effects.

Preparation of self-preserving personal care cosmetic products using multifunctional ingredients and other cosmetic ingredients

The development of self-preserving personal care cosmetics represents a significant advancement in the cosmetics industry, offering safer and more natural alternatives to consumers. This study focused on the preparation of such formulations using multifunctional ingredients along with other cosmetic components. Five unique multifunctional ingredients (MFIs) were identified based on their antimicrobial properties: sodium coco PG-dimonium chloride phosphate, ricinoleic acid, palmitoleic acid, raspberry ketone, and sorbitan caprylate. Through meticulous experimentation, 150 combinations of MFIs were prepared and tested to understand their synergistic actions. From these trials, three synergistic antimicrobial compositions were determined: sodium coco PG-dimonium chloride phosphate: ricinoleic acid: raspberry ketone in the ratios 1:6.3:6.3 and 1:6.3:15.7. Sodium coco PG-dimonium chloride phosphate: palmitoleic acid: sorbitan caprylate at a ratio of 1:12.5:37.5. These synergistic compositions exhibited enhanced antimicrobial efficacy compared with their individual components, as evidenced by their lower Minimum Inhibitory Concentration values. Incorporating these formulations into three distinct personal care cosmetic products, including a color protection shampoo, body wash shower gel, and skin-lightening cream, the study further validated their effectiveness. A Preservation Challenge Test study revealed that all three antimicrobial compositions successfully preserved the cosmetic formulations for up to 28 days. This method of product preservation not only ensures consumer safety and stability but also reduces the need for potentially conventional preservatives. In conclusion, the appropriate use of multifunctional ingredients in combination with meticulous formulation techniques has led to the successful development of self-preserving personal care cosmetics. These formulations offer a promising avenue for the cosmetic industry, catering to the rising demand for natural, effective, and consumer-friendly cosmetic products.

Antibacterial characteristics and mechanistic insights of combined tea polyphenols, Nisin, and epsilon-polylysine against feline oral pathogens: a comprehensive transcriptomic and metabolomic analysis.

This study evaluates the antibacterial characteristics and mechanisms of combined tea polyphenols (TPs), Nisin, and ε-polylysine (PL) against Streptococcus canis, Streptococcus minor, Streptococcus mutans, and Actinomyces oris, common zoonotic pathogens in companion animals. Pathogenic strains were isolated from feline oral cavities and assessed using minimum inhibitory concentration (MIC) tests, inhibition zone assays, growth kinetics, and biofilm inhibition studies. Among single agents, PL exhibited the lowest MIC values against all four pathogens. TP showed significant resistance against S. minor, and Nisin against S. mutans. The combination treatment (Comb) of TP, Nisin, and PL in a ratio of 13:5:1 demonstrated broad-spectrum antibacterial activity, maintaining low MIC values, forming large inhibition zones, prolonging the bacterial lag phase, reducing growth rates, and inhibiting biofilm formation. RNA sequencing and metabolomic analysis indicated that TP, Nisin, and PL inhibited various membrane-bound carbohydrate-specific transferases through the phosphoenolpyruvate-dependent phosphotransferase system in S. canis, disrupting carbohydrate uptake. They also downregulated glycolysis and the citric acid cycle, inhibiting cellular energy metabolism. Additionally, they modulated the activities of peptidoglycan glycosyltransferases and d-alanyl-d-alanine carboxypeptidase, interfering with peptidoglycan cross-linking and bacterial cell wall stability. The Comb therapy significantly enhances antibacterial efficacy by targeting multiple bacterial pathways, offering potential applications in food and pharmaceutical antimicrobials.

GC–MS based metabolomic profiling of Aporosa cardiosperma (Gaertn.) Merr. leaf extracts and evaluating its therapeutic potential

Aporosa cardiosperma is a plant species majorly found in the Indian Western Ghats that belongs to the phyllanthaceae family with ethnobotanical importance. Using a Fourier Transform-Infrared Spectrometer (FT-IR) and Gas Chromatography-Mass Spectrometry (GC–MS) for evaluating leaf extracts of A. cardiosperma, significant functional groups and metabolite constituents were determined, and its total flavonoid, phenol, and tannin content were quantified. Further, its antibacterial efficacy was investigated against microorganisms that cause fish and human disease and are resistant to common antibiotics, including Staphylococcus aureus, Bacillus subtilis, Mycobacterium tuberculosis, Klebsiella pneumoniae, Aeromonas hydrophila, and Pseudomonas aeruginosa. Regarding the outcomes of GC–MS analysis, the primary metabolites in the A. cardiosperma leaf extracts were heneicosane (57.06%), silane (13.60%), 1-heptadecene (10.09%), 3-hexadecene (9.99%), and pentadecane (9.54%). In comparison to other solvents, methanolic extract of A. cardiosperma leaves had increased phenolic, flavonoid, and tannin content; these findings are consistent with in vitro antioxidant potential and obtained that the methanolic extract (100 µg/mL) exhibited the higher percentage of inhibition in DPPH (82.35%), FRAP (86.20%), metal chelating (72.32%), and ABTS (86.06%) antioxidant assays respectively. Similar findings were found regarding the antibacterial efficacy against pathogenic bacteria. Comparatively, to other extracts, methanolic extracts showed more significant antibacterial activity at a lower minimum inhibitory concentration (MIC) value (250 µg/mL), whilst ethyl acetate and hexane solvent extracts of A. cardiosperma leaves had higher MIC values 500 µg/mL and 1000 µg/mL respectively. The antimicrobial potential was validated by investigating bacterial growth through the extracts acquired MICs and sub-MICs range. Bacterial growth was completely inhibited at the determined MIC range. In conclusion, A. cardiosperma leaf extract's phytochemical fingerprint has been determined, and its potent antibacterial and antioxidant activities were discovered. These findings of the current study will pave the way for developing herbal treatments from A. cardiosperma for various fish and human diseases.