In silico and in vitro studies of isolated constituents from Callistemon citrinus leaves: Anti-microbial potential and inhibition of iNOS activity

Authors: ABDELMALEK, ERENY - University Of Mississippi; ZULFIQAR, FAZILA - University Of Mississippi; ALBADRY, MOHAMED - University Of Mississippi; KHAN, SHABANA - University Of Mississippi; Meepagala, Kumudini; RAMADAN, MAHMOUD - Assuit University; DARWISH, FATEN - Assuit University; ASSAF, MAHMOUD - Assuit University; ROSS, SAMIR - University Of Mississippi

Submitted to: Phytochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2021
Publication Date: 4/9/2021
Citation: Abdelmalek, E.M., Zulfiqar, F., Albadry, M.A., Khan, S.I., Meepagala, K.M., Ramadan, M.A., Darwish, F.M., Assaf, M.H., Ross, S.A. 2021. In silico and in vitro studies of isolated constituents from Callistemon citrinus leaves: Anti-microbial potential and inhibition of iNOS activity. Phytochemistry. 185. https://doi.org/10.1016/j.phytochem.2021.112745.
DOI: https://doi.org/10.1016/j.phytochem.2021.112745

Interpretive Summary: Chemical investigation of the methanol extract of the leaves of Callistemon citrinus, also known as the bottle brush tree collected in Egypt, resulted in the isolation of five undescribed compounds, acylphloroglucinol derivatives some of which are known for antibacterial activity and four isomers of monoterpene gallate derivatives in addition to twenty nine known compounds including phloroglucinol derivatives, chromone-C-glycosides, triterpenes, flavonoids and gallates. Structure elucidation was achieved by means spectroscopic experiments as well as comparison with the published literature. All the isolated compounds were tested for their anti-inflammatory activity.

Technical Abstract: Callistemon citrinus, also widely known as “bottle brush tree” is a flowering plant of the Myrtaceae family, native to Australia, but widely found in various parts of the world, including South America and Asia’s subtropical and tropical regions. Chemical investigation of the methanol extract of the leaves of Callistemon citrinus collected from Egypt, resulted in the isolation of five previously unreported compounds, one acylphloroglucinol derivative and four isomers of monoterpene gallate derivatives in addition to twenty nine known compounds including phloroglucinol derivatives, chromone-C-glycosides, triterpenes, flavonoids and gallates. Structure elucidation was achieved by means of 1D and 2D NMR spectroscopic experiments, HRESIMS, optical rotation, as well as comparison with the literature. All the isolated compounds were tested for their anti-inflammatory activity.