Lemon myrtle (Backhousia citriodora) (hereinafter referred to as LM), which is native to Australia, is widely used in tea and cooking for its lemon-like aroma. There are many products on the market that utilize its antibacterial properties. Among the components of essential oil (hereinafter referred to as EO) extracted from LM leaves and stems, citral accounts for 90-97%, but LM leaves are also rich in polyphenols that are rarely contained in EO, and have not only conventional aromatic and antibacterial effects, but also antiviral, antioxidant, anti-inflammatory, anti-disease prevention, and other effects on humans. We developed a method for extracting an antibacterial and antiviral agent that does not contain citral and is mainly composed of flavonoid glycosides such as hyperoside and myricitrin. We have discovered a method to simultaneously exhibit suppressive effects on Pseudomonas, Klebsiella pneumoniae, and influenza virus.