Eucalyptus Oils Phytochemical Composition in Correlation with Their Newly Explored Anti-SARS-CoV-2 Potential: in Vitro and in Silico Approaches

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the latest arisen contagious respiratory pathogen related to the global outbreak of atypical pneumonia pandemic (COVID-19). The essential oils (EOs) of Eucalyptus camaldulensis, E. ficifolia F. Muell., E. citriodora Hook, E. globulus Labill, E. sideroxylon Cunn. ex Woolls, and E. torquata Luehm. were investigated for its antiviral activity against SARS-CoV-2. The EOs phytochemical composition was determined using GC/MS analysis. Correlation with the explored antiviral activity was also studied using multi-variate data analysis and Pearson's correlation. The antiviral MTT and cytopathic effect inhibition assays revealed very potent and promising anti SARS-CoV-2 potential for E. citriodora EO (IC50 = 0.00019 µg/mL and SI = 26.27). The multivariate analysis revealed α-pinene, α-terpinyl acetate, globulol, γ -terpinene, and pinocarvone were the main biomarkers for E. citriodora oil. Pearson's correlation revealed that globulol is the top positively correlated compound in E. citriodora oil to its newly explored potent anti SARS-CoV-2 potential. A molecular simulation was performed on globulol via docking in the main active sites of both SARS-CoV-2 viral main protease (Mpro) and spike protein (S). In silico predictive ADMET study was also developed to investigate the pharmacokinetic profile and predict globulol toxicity. The obtained in silico, in vitro and Pearson's correlation results were aligned showing promising SARS-CoV-2 inhibitory activity of E. citriodora and globulol. This study is a first record for E. citriodora EO as a novel lead exhibiting potent in vitro, and in silico anti SARS-CoV-2 potential and suggesting its component globulol as a promising candidate for further extensive in silico, in vitro and in vivo anti-COVID studies.

Therapeutic effects of Stemmoside C against Salmonella enterica serotype typhimurium infected BALB/c mice

Salmonella is a Gram-negative bacterium that causes gastrointestinal diseases in 20 to 40 million people globally. Stemmoside C is a steroidal glycoside isolated from Argel, although its antibacterial and antibiofilm properties have not been studied. The antibacterial activity of Stemmoside C against Salmonella enterica was revealed, where MIC of the compound was 16 μg/mL (0.15 µM). Biofilm-associated Stemmoside C treatment destroyed S. typhi cells and reduced viable S. typhi numbers below detectable levels. When compared to Stemmoside C or Ciprofluxacin-treated mice, infected BALB/c mice had a greater death rate and a larger bacterial blood burden. The protective effects of orally administered Stemmoside C at dose of 25 and 50 mg/kg b.wt. against bacterial infection was associated with reduction in the levels of inflammatory cytokines (IFN-γ, Il-1β, IL-2, IL-6, MPO, and TNF-α) and elevation of anti-inflammatory cytokine (IL-10 and IL-12) in serum. Where, Stemmoside C at dose of 50 mg/kg b.wt. regulated the levels almost as normal control group and demonstrated apparently normal intestinal sections. It also resulted in a decrease in the number of viable S. typhi retrieved from feces. Stemmoside C is a promising drug for the treatment or prevention of S. typhimurium infection.

Curcumin clarithromycin nano-form a promising agent to fight Helicobacter pylori infections

Helicobacter pylori (H. pylori) is the main cause of gastric diseases. However, the traditional antibiotic treatment of H. pylori is limited due to increased antibiotic resistance, low efficacy, and low drug concentration in the stomach. This study developed a Nano-emulsion system with ability to carry Curcumin and Clarithromycin to protect them against stomach acidity and increase their efficacy against H. pylori. We used oil in water emulsion system to prepare a novel Curcumin Clarithromycin Nano-Emulsion (Cur-CLR-NE). The nano-emulsion was validated by dynamic light scattering (DLS) technique, zeta potential; transmission electron microscopy (mean particle size 48 nm), UV-visible scanning and Fourier transform infrared spectroscopy (FT-IR). The in vitro assay of Cur-CLR-NE against H. pylori was evaluated by minimum inhibitory concentration (12.5 to 6.26 µg/mL), minimum bactericidal concentration (MBC) and anti-biofilm that showed a higher inhibitory effect of Cur-CLR-NE in compere with, free curcumin and clarithromycin against H. pylori. The in vivo results indicated that Cur-CLR-NE showed higher H. pylori clearance effect than free clarithromycin or curcumin under the same administration frequency and the same dose regimen. Histological analysis clearly showed that curcumin is highly effective in repairing damaged tissue. In addition, a potent synergistic effect was obvious between clarithromycin and curcumin in nano-emulsion system. The inflammation, superficial damage, the symptoms of gastritis including erosion in the mouse gastric mucosa, necrosis of the gastric epithelium gastric glands and interstitial oedema of tunica muscularis were observed in the positive control infected mice and absent from treated mice with Cur-CLR-NE.

Natural compounds as possible anti-SARS-CoV-2 therapeutic agents: an in-vitro and in-silico study

WHO declared severe acute respiratory syndrome coronavirus-2' (SARS-CoV-2) was global health emergency since 2020. In our study eighteen natural compounds were investigated for possible anti-SARS-CoV-2 potential, where the most potent natural compounds were ursolic acid and dioscin with IC50 value of 4.49 µg/mL and 7.11 µg/mL, respectively. Hesperidin, catechin, diosmin, isorhamnetin-3-O-glucoside and hyperoside showed medium antiviral activity with IC50 value of 20.87, 22.57, 38.92, 39.62 and 47.10 µg/mL, respectively. Molecular modelling studies including docking study and predictive ADME study were performed on all tested molecules. Their binding energies after docking were calculated and their orientations at the active sites of both SARS-CoV-2 main protease (Mpro) and spike (S) receptors were visualised and compared to the downloaded ligands. Also, the predictive ADME studies showed good pharmacokinetic properties of most of the tested compounds. The obtained in silico results obtained confirmed that many of the tested compounds are promising SARS-CoV-2 inhibitors.

Prevalence and In Vivo Assessment of Virulence in Shiga Toxin-Producing Escherichia coli Clinical Isolates from Greater Cairo Area

Background: Shiga toxin-producing Escherichia coli (STEC) has been identified as an important etiologic agent of human disease in Egypt. Aims: To investigate the occurrence and describe the characterization as well as prevalence of STEC in Greater Cairo hospitals as well as molecular characterization of virulence and resistance genes. Methods: Four hundred seventy E. coli clinical isolates were collected from eight hospitals and analyzed by genotypic and phenotypic methods for STEC, followed by histopathological examination and scoring of different organs lesions. Results: The highest proportion of isolates was from urine (151 isolates), whereas the lowest was from splenic drain (3 isolates). In tandem, when serogrouping was performed, 15 serogroups were obtained where the most prevalent was O157 and the least prevalent was O151. All isolates were positive when screened for identity gene gad A, while only typable strains were screened for seven virulence genes stx1 (gene encoding Shiga toxin 1), stx2 (gene encoding Shiga toxin 2), tsh (gene encoding thermostable hemagglutinin), eaeA (gene encoding intimin), invE (gene encoding invasion protein), aggR (gene encoding aggregative adherence transcriptional regulator), and astA (aspartate transaminase) where the prevalence was 48%, 30%, 50%, 57%, 7.5%, 12%, and 58%, respectively. Of 254 typable isolates, 152 were STEC carrying stx1 or stx2 genes or both. Conclusions: Relying on in vivo comparison between different E. coli pathotypes via histopathological examination of different organs, E. coli pathotypes could be divided into mild virulent, moderate virulent, and high virulent strains. Statistical analysis revealed significant correlation between different serogroups and presence of virulence genes.

9-Methoxyellipticine: Antibacterial Bioactive Compound Isolated from Ochrosia elliptica Labill. Roots

Antibacterial resistance bears a major threat to human health worldwide, causing about 1.2 million deaths per year. It is noteworthy that carbazole derivatives have shown a potential antibacterial activity, for example, 9-methoxyellipticine, which was isolated from Ochrosia elliptica Labill. roots (Apocynaceae) in the present study. An in vitro screening of the antibacterial activity of 9-methoxyellipticine was investigated against four multidrug-resistant (MDR) Klebsiella pneumoniae and Shiga toxin-producing Escherichia coli (STEC O157) as Gram-negative bacteria, in addition to Methicillin-resistant Staphylococcus aureus (MRSA) with Bacillus cereus as Gram-positive bacteria. The compound had significant antibacterial activity against the two Gram-negative isolates and lower activity against the Gram-positive ones. The synergistic use of 9-methoxyellipticine and antibiotics was successfully effective in reducing the MDR microorganisms. Lung pneumonia and kidney infection mice models were used to investigate the compound's efficacy in vivo for the first time. Noteworthy reductions in K. pneumoniae and STEC shedding and the colonization were observed, with a reduction in pro-inflammatory factors and immunoglobulin levels. Other related lesions such as inflammatory cell infiltration, alveolar interstitial congestion, and edema were noticed to occur, lessened to different limits. The anti-STEC and anti-K. pneumoniae activities of 9-methoxyellipticine were revealed, providing a new alternative against MDR nosocomial infections.

Luteolin 4′-Neohesperidoside Inhibits Clinically Isolated Resistant Bacteria In Vitro and In Vivo

Multidrug resistance (MDR) pathogens are usually associated with higher morbidity and mortality rates. Flavonoids are good candidates for the development of new potential antimicrobials. This research investigated whether luteolin 4′-neohesperidoside (L4N) has antibacterial and synergistic activities against four antibiotic-resistant pathogens: methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae, fosA-positive shiga toxin producing the Escherichia coli serogroup O111 (STEC O111), and Bacillus cereus. In vitro antimicrobial susceptibility testing revealed highly potent anti-MRSA (MIC of 106.66 ± 6.95 µg/mL), anti-K. pneumoniae (MIC of 53.33 ± 8.47 µg/mL) and anti-STEC O111 (MIC of 26.66 ± 5.23 µg/mL) activities. Significant synergistic combination was clearly noted in the case of gentamycin (GEN) against Gram-negative bacteria. In the case of B. cereus, the combination of vancomycin (VAN) with L4N could efficiently inhibit bacterial growth, despite the pathogen being VAN-resistant (MIC of 213.33 ± 7.9 µg/mL). In vivo evaluation of L4N showed significant decreases in K. pneumoniae and STEC shedding and colonization. Treatment could significantly diminish the levels of pro-inflammatory markers, tumor necrosis factor-alpha (TNF-α), and immunoglobulin (IgM). Additionally, the renal and pulmonary lesions were remarkably enhanced, with a significant decrease in the bacterial loads in the tissues. Finally, this study presents L4N as a potent substitute for traditional antibiotics with anti-STEC O111 and anti-K. pneumoniae potential, a finding which is reported here for the first time.

Bioassay-Guided Isolation of Antimicrobial Components and LC/QToF Profile of Plumeria obtusa: Potential for the Treatment of Antimicrobial Resistance

The methanolic fraction (M-F) of the total extract (TE) of Plumeria obtusa L. aerial parts showed promising antibacterial effects against the MDR (multidrug-resistant) gram-negative pathogens Klebsiella pneumoniae and Escherichia coli O157:H7 [Shiga toxin-producing E. coli (STEC)]. In addition, M-F had a synergistic effect (in combination with vancomycin) against the MDR gram-positive strains MRSA (methicillin-resistant Staphylococcus aureus) and Bacillus cereus. After treating the K. pneumoniae- and STEC-infected mice with M-F (25 mg/kg, i.p.), the level of IgM and TNF-α was decreased and the severity of pathological lesions were reduced better than that observed after administration of gentamycin (33 mg/kg, i.p.). Thirty-seven compounds including 10 plumeria-type iridoids and 18 phenolics, 7 quinoline derivatives, 1 amino acid, and 1 fatty acid were identified in TE using LC/ESI-QToF. Furthermore, five compounds; kaempferol 3-O-rutinoside (M1), quercetin 3-O-rutinoside (M2), glochiflavanoside B (M3), plumieride (M4), and 13-O-caffeoylplumieride (M5) were isolated from M-F. M5 was active against K. pneumoniae (MIC of 64 μg/mL) and STEC (MIC of 32 μg/mL). These findings suggested that M-F and M5 are promising antimicrobial natural products for combating MDR K. pneumoniae and STEC nosocomial infections.

A Study on Multidrug-Resistant Escherichia coli Clinical Isolates from Different Hospitals in Greater Cairo

The biological fitness cost of antibiotic resistance is a key parameter in determining the rate of appearance and spread of antibiotic-resistant bacteria in Egypt. Our study aimed to investigate the prevalence of antibiotic resistance among Escherichia coli clinical isolates from Greater Cairo area hospitals. A total of 537 clinical isolates were recovered from samples of urine, diarrheal specimen, pus, wound culture, gastric wound, blood, drain culture, sputum, high vaginal swab, abscess, amniotic fluid, ventilator, burn swab, splenic drain culture, and unknown site of infection during different seasons. All isolates were subjected to phenotypic and genotypic susceptibility testing for colistin, nitrofurantoin, fosfomycin, and trimethoprim, quinolones, and β-lactam resistance. Our results revealed that 42.7% of the isolates harbored at least one resistance encoding gene, 10% harboring 2, 0.6% harboring 3, and 0.85% harboring 4 resistance-encoding genes. PCR reported the prevalence of resistance genes as follows: bla-SHV 13.4%, mcr-1 0.6%, qnr-A 23.8%, fos-A 1.06%, nfs-A 3.6%, and dfr-A 25.5%. We reported that three isolates carried the mcr-1 gene encoding colistin resistance from three different hospitals. Upon performing sequencing and phylogenetic analysis on the three positive mcr-1 isolates (MT890587, MT890588, and MT890589), the three isolates showed 100% identity with themselves, with some strains from Egypt and Japan, and 99.9% identity with an isolate from China.