Abstract
Overproduction of reactive species and microbial resistance to the existent antibiotics are still great health challenges. The current study aimed to evaluate the antioxidant and antimicrobial activities of Pterygota alata leaves extracts, in addition to isolation and identification of their chemical constituents. In vitro antioxidant activity was explored using 2,2'-diphenyl-1-picrylhydrazyl radical scavenging assay (DPPH), whereas the in vitro antimicrobial activity was evaluated using the disc agar plate method. Chemical constituents of the leaves extracts were isolated through column chromatography, and then identified using 1H, 13C-NMR and IR spectroscopic tools. In the DPPH assay; the half maximal inhibitory concentration (IC50) value of the total extract was 72.4 ± 1.4 µg/ ml, relative to 11.2 ± 0.6 µg/ ml of the standard ascorbic acid. On the other hand; the antimicrobial results revealed that the ethyl acetate extract showed the strongest inhibitory potential against most of the tested microbes with inhibition zones of 16.8- 22.8 mm, followed by petroleum ether with inhibition zones between 13.4- 19.6 mm, and n-BuOH with inhibition zones ranging from 14.9-19.3 mm. These results were compared with the standard antibiotics such as; Amphatricin β, Ampicillin, and Gentamycin. Furthermore; chromatographic isolation of the different solvents extracts resulted in the isolation of five phytoconstituents, their chemical structures were assigned as; β-sitosterol (1), apigenin-7-β-D-glycoside (2), gallic acid (3), luteolin-7-β-D-glucoside (4), and 4'-methoxy myricetin-3-β-D-glucoside (5). Current findings suggested that leaf extracts of P. alata could be used for the development of natural drugs; to treat microbial infections and reactive oxygen species (ROS) associated disorders.
Highlights
Reactive oxygen species (ROS) and\ or reactive nitrogen species (RNS) are highly energetic molecules carrying single electrons able to penetrate cells and tissues
The assay was based on the decrease in absorption of the diphenyl-1-picrylhydrazyl radical scavenging assay (DPPH) solution after addition of the antioxidant measured at 515 nm
Numerous plant extracts belonging to different species were screened for their phytochemical constituents, which contributed to their demonstrated bioactivities such as; antioxidant, antimicrobial and cytotoxic activities (Ghareeb et al, 2015a, b; Ghareeb et al, 2016; Ghareeb et al, 2017; Hamed et al, 2017a, b; Madkour et al, 2017; Saad, 2017a, b)
Summary
Reactive oxygen species (ROS) and\ or reactive nitrogen species (RNS) are highly energetic molecules carrying single electrons able to penetrate cells and tissues. Over-production of these reactive species led to the generation of a highly risk phenomenon known as oxidative stress. This phenomenon was accompanied by several health disorders such as; inflammations and cancer diseases. Br. is a large deciduous tree known as Budah coconut tree This plant was distributed in Asia especially in China; Vietnam, India, Philippines and Myanmar (Lin et al, 2010). From the biological point of view; P. alata showed numerous biological activities such as; antioxidant (Jahan et al, 2014); anti-hyperglycemic (El-Sherei et al, 2018); and anti-oxidative stress (El-Sherei et al, 2018). ; the current study aimed to investigate the chemical profile of P. alata, and to explore its in vitro antimicrobial and antioxidant potentials
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