The pyran ring isopentene group: an overlooked antimicrobial active group in prenylated flavonoids

Abstract

Prenylated flavonoids show antibacterial activity towards Staphylococcus aureus (S. aureus). Previous studies have suggested that the prenyl side-chain is an important active group for antimicrobial activity. However, prenylated flavonoids also often contain a pyran ring isopentene group. Few studies have explored the contribution of the pyran ring isopentene group to antibacterial activity. In this study, the antibacterial activities of structurally related flavonoid compounds from mulberry root bark were studied by detecting the minimum inhibitory concentration (MIC) and colony counting. These flavonoid compounds all exhibited antibacterial activities against S. aureus ATCC6538, S. aureus ATCC25923 and methicillin-resistant S. aureus (MRSA) ATCC43300 with MIC values of 7.3–248.2 μmol/L, 7.3–330.9 μmol/L, and 7.3–330.9 μmol/L, respectively. Structure-activity relationship analyses demonstrated that the pyran ring isopentene group plays an important role in antibacterial activity. Thus, the pyran ring isopentene group is an overlooked antimicrobial active group in prenylated flavonoids.

GRAPHICAL ABSTRACT

Keywords:

• Mulberry root bark
• prenylated flavonoids
• antibacterial activity
• pyran ring isopentane groups
• prenyl side-chains

Disclosure statement

No potential competing interest was reported by the authors.

Additional information

Funding

This work was supported by Foundation of Research and Development Plan in Key Fields of Guangdong Province (2020B020225005), Natural Science Foundation of Guangdong Province (2020A1515011026, 2018A0303130016), Guangdong Basic and Applied Basic Research Foundation (2019B1515210018), Agricultural Competitive Industry Discipline Team Building Project of Guangdong Academy of Agricultural Sciences (202119TD), Excellent Doctors’ Foundation of Guangdong Academy of Agricultural Sciences (R2021YJ-YB1002), Independent Research and Development Projects of Maoming Laboratory (2021ZZ004) and Guangdong Provincial Special Fund for Modern Agriculture Industry Technology Innovation Teams (2021KJ124).