Flavonoid compounds and antibacterial mechanisms of different parts of white guava (Psidium guajava L. cv. Pearl)

Abstract

The flavonoid compositions, extracted from leaves, peel and flesh of white guava (Psidium guajava L. cv. Pearl), were identified and quantified by UPLC-ESI-QTOF-MS, HPLC-ESI-MS/MS and HPLC. The main components of three extracts all were quercetin-glycosides, but the proportion and content of quercetin-hexoside and quercetin-pentoside in each extract were different. Based on the measurements of MIC, MBC value and time killing curve, it emerged that 3 flavonoid extracts of white guava had good antibacterial effects on four pathogenic bacteria. White guava leaves flavonoids (WGLF) concentrations of 5.00 mg/mL and 0.625 mg/mL could change the micro-morphology of Escherichia coli and Staphylococcus aureus. It suggested that the antibacterial mechanism of WGLF on gram-positive and gram-negative bacteria was to destroy the structure and function of the cell membrane. It is indicated that the flavonoid extracts from white guava is a potential natural antimicrobial agent.

Graphical abstract

KEYWORDS:

• Psidium guajava L.
• flavonoid compounds
• UPLC-ESI-QTOF-MS
• HPLC-ESI-MS/MS
• antibacterial activity
• antibacterial mechanism

Disclosure statement

No conflict of interest exists regarding the submission of this manuscript, and the manuscript was approved by all authors for publication.

Additional information

Funding

This research was supported by Science and Technology Planning Project of Guangdong Province, China, under Grant [number 201604020138].