TY  - BOOK
AU  - Galano, Ralph Dominic C.,
AU  - Japson, Angela B.,
AU  - Lague, Inah Krizia O.,
AU  - Makinano, Jyrah Mee T.,
AU  - Mondarte, Khylla Gayle,
AU  - Mopon, Matt Markel,
AU  - Marquianos, Lance,
AU  - Mose, Ma. Lucia Beatriz,
AU  - Ngo, Timothy Bryan,
AU  - Omictin, Jannie Lyka,
AU  - Ong, Cathelaine Diane,
AU  - Perilla, Isabela Louise,
AU  - Quimbo, Miguel Luis,
TI  - Anti-quorum sensing activity of Psidium guajava L. methanolic leaf extracts against Pseudomonas aeruginosa: an in vitro study 
PY  - 2026///.
CY  - Subangdaku, Mandaue City
PB  - University of Cebu - College of Medicine Foundation, Inc.
KW  - Bacterial infection
KW  - Antimicrobial resistance
KW  - Pseudomonas aeruginosa
KW  - Multidrug-resistant (MDR)
KW  - Hospital acquired infection
KW  - Anti-quorum sensing
KW  - Psidium guajava L
KW  - Drug resistant bacteria
N1  - Includes bibliographical references; Adult
N2  - "The emergence of multidrug-resistant Pseudomonas aeruginosa necessitates alternative antimicrobial strategies, such as quorum sensing (QS) inhibition, which targets virulence without exerting selective survival pressure. This study evaluated the anti-quorum sensing and antibiofilm activity of Psidium quajava L. methanolic leaf extracts against P. aeruginosa in vitro. Leaves collected from Medellin, Cebu, were extracted via methanolic maceration, yielding a 5.493% crude extract. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were determined using a resazurin-based microplate broth dilution assay. Anti-QS activity was quantitatively assessed by measuring biofilm inhibition at sub-inhibitory concentrations using a crystal violet assay, with cinnamaldehyde as the positive control. The extract exhibited poor direct antimicrobial activity, recording an MIC of 12.5 mg/mL and an MBC of >12.5 mg/mL. However, it demonstrated potent, dose-dependent antibiofilm efficacy. At the baseline MIC (12.5 mg/mL), the extract achieved a 96.93% biofilm inhibition rate, remaining significantly effective at 87.68% (6.25 mg/mL) and 73.20% (3.125 mg/mL). Welch's t-test revealed the extract performs comparably to the commercial standard, cinnamaldehyde ($p = 0.408$). Furthermore, Welch's ANOVA indicated maximum statistical efficacy was achieved at 6.25 mg/mL, with no significant difference in inhibition compared to the maximum dose. These findings establish that while P. guajava methanolic leaf extract possesses weak bactericidal effects, it is a highly capable anti-quorum sensing agent that effectively disrupts biofilm formation, offering a promising alternative therapeutic strategy against antibiotic-resistant infections." --Abstact
ER  -