In Silico, Chemical Profiling and In Vitro Analysis of Ethanolic Preparation of Hydrocotyle Asiatica Q and 6C Against Staphylococcus aureus

LC-QTOF-MS Chemical Characterization, Cytotoxicity, and Antimicrobial Activity of Blue Geopropolis: An Emerging Type of Brazilian Propolis

Background/Objectives: This study characterized blue geopropolis from Melipona quadrifasciata quadrifasciata (southern Brazil) by comparing its chemical composition, cytotoxicity, antimicrobial activity, and coloration mechanisms directly against green and red Apis mellifera propolis under identical experimental conditions. Methods: Ethanolic extracts of blue geopropolis, green, and red propolis were prepared, followed by hexane and chloroform fractionation. Chemical composition was analyzed by LC-qTOF-MS. Cytotoxicity was assessed in L929 fibroblasts, and antimicrobial activity was determined by minimum inhibitory concentration (MIC) assays against bacterial and fungal strains. The blue coloration was investigated using NaOH and FeCl3 treatments to evaluate the possible involvement of phenolic–iron complexes. Results: Fifty-nine compounds were identified across the three samples, revealing several shared phenolic constituents as well as distinctive chemical features. None of the extracts showed activity against Gram-negative bacteria, including Escherichia coli and Pseudomonas aeruginosa (MIC > 1000 µg/mL). In contrast, activity was observed against Gram-positive bacteria, with MIC values ranging from 20.8 to 1000 µg/mL. Among the samples tested, blue geopropolis showed the strongest activity against Gram-positive bacteria. Blue geopropolis exhibited no significant activity against Candida albicans or Candida parapsilosis (MFC > 1000 µg/mL) but showed variable activity against Sporothrix spp. The colorimetric assay indicated that phenolic–iron complexation may contribute to the blue color. Conclusions: Despite its distinct entomological origin, blue geopropolis shared chemical traits with green and red propolis while demonstrating superior Gram-positive antibacterial activity, a higher selectivity index, and potential antifungal applications against Sporothrix spp., highlighting its promise for biotechnological and pharmacological use.

In Vitro Evaluation of Ocimum gratissimum Leaf (Scent Leaf) Extracts Against Selected Clinical Multidrug-Resistant Bacterial Isolates

The rise in multidrug-resistant (MDR) pathogens has made the search for alternative sources of antimicrobial agents a global priority.  This study investigated the phytochemical constituents, antioxidant capacity, and antibacterial activities of aqueous and ethanol leaf extracts of O. gratissimum against selected MDR clinical bacterial isolates (Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Klebsiella pneumoniae).  Phytochemical constituents and total antioxidant capacity of O. gratissimum were determined using standard laboratory procedures.  Antibacterial activity was assessed by the agar well diffusion method at concentrations ranging from 12.5 to 200 mg/mL, while minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using broth dilution techniques.  Data were expressed as mean ± standard deviation (SD), and statistical analysis was performed using one-way analysis of variance (ANOVA) at p < 0.05.  The ethanol extract produced a higher extraction yield (17.88%) than the aqueous extract (13.66%) and contained significantly greater amounts of phytochemicals (p < 0.05) and exhibited higher antioxidant capacity (240.53 ± 3.12 µg/mL) than the aqueous extract (228.19 ± 2.84 µg/mL) (p = 0.018).  Both extracts showed concentration-dependent antibacterial activity, although the ethanolic extract produced significantly larger inhibition zones ( p < 0.001).  Both extracts had an MIC of 25 mg/mL, while the ethanolic extract exhibited MBC values between 50-100 mg/mL.  These findings support the traditional therapeutic use of the plant and suggest its potential as a natural source of antimicrobial agents.  Further studies involving advanced phytochemical characterization, toxicity evaluation, and in vivo validation are recommended to support future pharmaceutical applications.

In vitro and in silico Investigation of Bioactive Compounds from Arcangelisia flava (L.) Merr. as Potential Antibacterial Agents

The growing threat of antibiotic resistance has prompted the hunt for new antibacterial medicines derived from natural sources. This work examined four compounds isolated from Arcangelisia flava (L.) Merr. roots: palmatine (1), fibraurin (2), β-sitosterol (3), and daucosterol (4). Both in vitro and in silico methods were used to assess their antibacterial properties. The antibacterial activity was assessed against Staphylococcus aureus, Bacillus subtilis, Vibrio alginolyticus, and Salmonella typhimurium using the broth microdilution method, which determined the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Palmatine (1) and fibraurin (2) had modest action against Gram-positive bacteria, with MIC values of 37.5 µg/mL. However, β-sitosterol (3) and daucosterol (4) showed lesser inhibition. Docking against bacterial protein targets (PDB IDs: 2ZDQ and 1HNJ) found palmatine (1) had the highest binding affinity (−7.7980 and −7.5464 kcal/mol, respectively), generating numerous hydrogen bonds and hydrophobic interactions. Pharmacophore analysis identified critical structural features - aromatic rings and hydrogen bond donors/acceptors - that are linked to the observed antibacterial activities. Palmatine (1) and fibraurin (2) met drug-likeness criteria, but β-sitosterol (3) and daucosterol (4) had limited absorption and potential for toxicity. Overall, (1) and fibraurin (2) are intriguing lead candidates for antibacterial drug development, requiring additional in vivo testing and structural tweaking to improve efficacy.

Chemical Profiling and Therapeutic Investigations on Grewia gamblei J.R. Drumm for Potential Antioxidant and Anti-inflammatory Applications: An in vitro and in silico Approach

LC-QTOF-MS metabolic profiling and anti-MRSA activity of Asparagus officinalis L. spear methanolic extract in a skin infection mouse model

Asparagus officinalis L. spears offer substantial potential as a functional food due to their rich nutritional profile and bioactive compounds. The emergence and spread of multidrug-resistant (MDR) pathogens, particularly in low- and medium-income countries, have necessitated extensive research and concerted efforts to combat infections. Novel One Health approaches are being sought to swiftly identify antibiotics that retain efficacy against these MDR pathogens. In this study, we evaluated the antibacterial activity of the methanolic extract of A. officinalis L. spears against Staphylococcus aureus USA300 (MARSA USA300); a MDR bacterium in vitro and in vivo. The methanolic extract demonstrated significant in vitro inhibition of the biofilm formation (IC50 value of 3.415 mg mL−1) and enhanced biofilm detachment (EC50 value of 1.573 mg mL−1) against MRSA. Additionally, topical treatment of MRSA USA300-infected BALB/C mice open lesion with the extract (50 mg mL−1 in 25% DMSO, once for three days) significantly reduced the bacterial count by 2.877 and 2.583 logs lower than that of the negative control). LC-QTOF/MS tentatively identified 99 compounds in the methanolic extract of A. officinalis spears. The findings obtained here demonstrate the potential of A. officinalis L. spears for pharmaceutical, agricultural, and food industry applications.

Chemical profile and bacterial potential of Psidium cattleyanum leaf extract against multidrug-resistant Staphylococcus aureus.

The increasing prevalence of multidrug-resistant (MDR) Staphylococcus aureus represents a major challenge for global public health and highlights the urgent need for new antimicrobial strategies. In this context, plant-derived compounds have emerged as promising sources of bioactive molecules with antimicrobial and antivirulence potential. The present study investigated the phytochemical profile and antimicrobial properties of a hydroalcoholic leaf extract of Psidium cattleyanum against reference and multidrug-resistant S. aureus strains. Phytochemical analyses revealed the presence of bioactive metabolites, particularly flavonoids and ellagic acid derivatives. Antimicrobial activity was evaluated through minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays, as well as growth curve analysis. The extract inhibited all tested strains, with MIC values ranging from 128 to 256 µg/mL and MBC values between 256 and 512 µg/mL. Additionally, the extract significantly reduced important virulence factors of S. aureus, including hemolytic activity and staphyloxanthin production. Synergistic interactions were also observed when the extract was combined with ciprofloxacin or gentamicin, markedly enhancing the antibacterial activity of both antibiotics. These findings indicate that P. cattleyanum contains bioactive compounds capable of inhibiting bacterial growth and attenuating virulence mechanisms in S. aureus, highlighting its potential as a source of natural agents for the development of alternative or adjunctive antimicrobial therapies against resistant pathogens.