Antimicrobial Activity of Psidium guajava Aqueous Extract against Sensitive and Resistant Bacterial Strains

Comprehensive assessment of the antidiarrheal properties of polyphenols from Psidium cattleianum Sabine's aerial parts

ETHNOPHARMACOLOGICAL RELEVANCE

Diarrhea is associated with high morbidity and mortality rates in developing countries and is ranked the second leading cause of infant mortality worldwide. Psidium cattleianum Sabine leaves have been traditionally used as an anti-diarrheal remedy, however, no scientific study has thoroughly investigated its anti-diarrheal potential.

AIM OF THE STUDY

To unravel the polyphenolic profile and explore the antidiarrheal potential of the defatted aqueous methanol extract (DAME) of Psidium cattleianum Sabine aerial parts through in vivo and in vitro experiments, alongside an inclusive in-silico analysis.

MATERIALS AND METHODS

The major polyphenolic compounds were purified and identified using chromatographic and spectroscopic techniques. The antidiarrheal activity was assessed using castor oil-induced diarrhea, gastrointestinal motility test, and castor oil-induced enteropooling in vivo models. Bacterial strains associated with diarrhea were used for the in vitro study. Molecular docking was investigated using Autodock Vina and OpenBabel tools. Moreover molecular dynamics study was performed using GROMACS, PyMOL and Bio3D package in R Studio.

RESULTS

Twelve polyphenols were isolated for the first time from the aerial parts of the Egyptian Psidium cattleianum Sabine and identified as; castalagin (1), rutin (2), kaempferol 3-O-β-D-rutinoside (3), guaijaverin (4), avicularin (5), quercetin 3-O-β-(3'-O-galloylxylopyranoside (6), verbascoside (7), quercetrin (8), gallic acid (9), methyl gallate (10), quercetin (11) and kaempferol (12). DAME (200, 400, and 800 mg/kg) significantly delayed the diarrheal onset by 1.5, 1.8, and 2.3 folds, respectively. The diarrheal inhibition percentage was 63.47, 82.69, and 92.31, respectively. The content of intestinal transit decreased by 27.38 %, 45.11 %, and 50.06 %. The Antidiarrheal index was 43.28, 66.74, and 84.22. E. coli, S. enterica, L. monocytogenes, and S. aureus demonstrated sensitivity to DAME, exhibiting inhibition zones (IZ) ranging from 10 to 25 mm. The docking conclusion shows that all identified polyphenols bind to the Kappa Opioid Receptor (KOR) and Beta-ketoacyl-acyl carrier protein synthase III (FabH), with promising results that confirm the credibility of the biological findings. Then, we selected the top-ranked phytocompounds verbascoside (7) based on their highest binding affinity scores for KOR and FabH -10.33 and -8.91 (Kcal/mol), respectively. Furthermore, 200 ns MD simulations performed on the KOR and FabH ligand-protein complexes, computed RMSD, RMSF, RG, PCA, DCCM, and free energy landscape (FEL), revealed stable conformations of the ligand-protein interactions throughout the simulations. These findings support that DAME is a promising alternative for managing diarrheal and bacterial infections related to gastrointestinal disorders. Our future direction is to formulate the extract in a suitable dosage form and implement clinical studies, while scaling up the in silico active phenolics for detailed mechanistic study is a promising approach.

Costa M, Avelar-Gonzalez FJ, Moreno-Flores AC, Vazquez-Pedroza E, Arreola-Guerra JM, González-Gámez M. Guava Leaf Extract Exhibits Antimicrobial Activity in Extensively Drug-Resistant (XDR) Acinetobacter baumannii

Currently, a global health crisis is being caused by microbial resistance, in which Acinetobacter baumannii plays a crucial role, being considered the highest-priority microorganism by the World Health Organization (WHO) for discovering new antibiotics. As a result, phytochemicals have emerged as a potential alternative to combat resistant strains, since they can exert antimicrobial activity through various mechanisms and, at the same time, represent a more natural and safe option. This study analyzes the antimicrobial effects of guava leaf extract in ten clinical isolates of extensively drug-resistant (XDR) A. baumannii, using the agar diffusion technique and the microdilution method to determine the minimum inhibitory concentrations (MICs). Additionally, possible improvements in antimicrobial activity after the purification of polyphenolic compounds and potential synergy with the antibiotic gentamicin are examined in this research. Moreover, the effect of the plant extract in cell line A549 derived from lung tissue was also evaluated. The extract exhibited antimicrobial activity against all the strains studied, and the purification of polyphenols along with the combination with gentamicin improved the extract activity. The presence of the plant extract induced morphological changes in the lung cells after 24 h of exposure. Therefore, Psidium guajava L. leaf extract is a potential antimicrobial agent.

Unravelling Post-harvest Ripening Metabolomics of a New White Variety Guava Fruit (Cv Arka Mridula) with Special Emphasis on Phenolics and Corresponding Antioxidants

The phenolic, antioxidant and metabolic profiling of a new white variety guava fruit Arka Mridula (AM) was performed during its storage at the room temperature (28 ± 2 °C). The comparative profiles were generated at three ripening stages (pre-ripe, ripe and over-ripe) of the fruit. Generally, a steady decrease of the phenolic and antioxidant content from the pre-ripe to the ripe stage and a subsequent increase from the ripe to over-ripe stage was observed. Further, a powerful correlation between the phenolic content and antioxidant principles was noted through the principal component analysis. We could identify 53  compounds for the hydro-methanolic fruit extract through LC and GC-MS aided metabolic analysis, and the identified compounds were dominated by phenolics (~ 44%). The statistical analysis revealed that phytochemicals catechin, myricitrin, myricetin, kaempferol glycosides and n-hexadecanoic acid contributed significantly towards the ripening process of AM, during the storage. The present study is expected to provide important insight into the ripening biochemistry of AM. Subsequently, it may help in the future development of metabolically stable guava cultivars with extended post-harvest shelf life.

Antimicrobial Strategies Proposed for the Treatment of S. pseudintermedius and Other Dermato-Pathogenic Staphylococcus spp. in Companion Animals: A Narrative Review

The treatment of dermato-pathogenic Staphylococcus spp., particularly Staphylococcus pseudintermedius, in companion animals presents significant challenges due to rising antimicrobial resistance. This review explores innovative strategies to combat these infections. We examined novel antimicrobials and the repurposing of existing drugs to enhance their efficacy against resistant strains. Additionally, we evaluate the potential of natural products, nanomaterials, and skin antiseptics as alternative treatments. The review also investigates the use of antimicrobial peptides and bacteriophages, highlighting their targeted action against staphylococcal pathogens. Furthermore, the role of adjuvants in antibiotic treatments, such as antimicrobial resistance breakers, is discussed, emphasizing their ability to enhance therapeutic outcomes. Our analysis underscores the importance of a multifaceted approach in developing effective antimicrobial strategies for companion animals, aiming to mitigate resistance and improve clinical management of staphylococcal skin infections.

Nutritional Composition, Mineral Profiling, In Vitro Antioxidant, Antibacterial and Enzyme Inhibitory Properties of Selected Indian Guava Cultivars Leaf Extract

Psidium guajava L. is a small evergreen tree known for its magnificent medicinal and nutritional value. This study aimed to evaluate the nutritional profile and in vitro pharmacological potentialities of the different leaf extracts of four cultivars of Psidium guajava namely Surka chitti, Allahabad safeda, Karela, and Lucknow-49. The standard procedures of the Association of Official Analytical Chemists (AOAC) were followed to carry out the nutritional analysis and all of the cultivars recorded the presence of elements at a nominal range. The highest presence of phenols (125.77 mg GAE/g) and flavonoids (92.38 mg QE/g) in the methanolic leaf extract of the Karela cultivar was recorded. A wide range of minerals such as sodium, phosphorus, magnesium, zinc, and boron were recorded with a higher percentage in the Karela cultivar of Psidium guajava. In the enzyme inhibitory assays, Allahabad safeda showed potential inhibition with an IC50 of 113.31 ± 1.07, 98.2 ± 0.66 and 95.73 ± 0.39 μg/mL in α-amylase, α-glucosidase, and tyrosinase inhibition assays, respectively. The strong antioxidant effect was established by Lucknow-49 (IC50 of 74.43 ± 1.86 μg/mL) and Allahabad safeda (IC50 of 78.93 ± 0.46 μg/mL) for ABTS and DPPH assays, respectively. The ethyl acetate and methanolic leaf extracts of the Allahabad safeda cultivar showed better inhibition against Pseudomonas aeruginosa with an MIC of 14.84 and 28.69 µg/mL, respectively. A decent mean zone of inhibition was recorded in methanolic leaf extract that ranged from 21-25 mm in diameter against the tested bacterial strains (Proteus vulgaris, Bacillus subtilis, and P. aeruginosa). This is the first scientific report on the comparative and comprehensive analysis of indigenous guava cultivars to evidently shortlist the elite cultivars with enriched dietary nutrition and biological activities.