Chemical constituents of Psidium guajava leaves and their antibacterial activity. - GreenMedInfo Summary
Chemical constituents of Psidium guajava leaves and their antibacterial activity.
Phytochemistry. 2021 Jun ;186:112746. Epub 2021 Mar 31. PMID: 33799191
Seven undescribed compounds, namely (+)-psiflavanone A, (-)-psiflavanone A, (+)-psiflavanone B, (-)-psiflavanone B, (+)-psiketide, (-)-psiketide, and psidinone, were isolated and chirally separated from the 95%-ethanol extract of Psidium guajava leaves. (+)/(-)-Psiflavanone A and (+)/(-)-psiflavanone B are two pairs of rare enantiomeric C-benzoylated flavanones isolated from the title plant for the first time. (+)/(-)-Psiketide are a pair of enantiomeric aromatic polyketides, and psidinone is the first example of a Cphenanthrenediquinone with an angle-type 6/6/6 tricyclic skeleton. Their structures were identified by extensive analysis of HRESIMS, UV, IR, NMR, and calculated electronic circular dichroism (ECD) data. Particularly, the structures of (+)-psiflavanone A, (-)-psiflavanone A, (+)-psiflavanone B, and psidinone were further confirmed by X-ray diffraction. Psidinone exhibited antibacterial activity against Staphylococcus aureus, Staphylococcus epidermidis, and Mycobacterium Smegmatis mc155, with minimum inhibitory concentrations (MICs) of 16, 8, and 0.5 μM, respectively. These results not only highlight the chemical diversity and biological activity of P. guajava but are also expected to pave way for its further expansion to other applications in future.