Correlation between Antibacterial Activity and Free-Radical Scavenging: In-Vitro Evaluation of Polar/Non-Polar Extracts from 25 Plants
Date
2020-01-15
Authors
Rayan, Mahmoud
Abu-Farich, Baheer
Basha, Walid
Rayan, Anwar
Abu-Lafi, Saleh
Journal Title
Journal ISSN
Volume Title
Publisher
MDPI
Abstract
Objectives: The current study aimed to measure the antioxidant and antibacterial activities
of 25 wild Palestinian edible plants, which were subjected to extraction by polar and non-polar solvents.
Correlations between free radical scavenging activity and antibacterial activity of the extracts were
assessed for both polar and non-polar fractions. Materials: Twenty-five wild edible plant species that
are frequently consumed by people in Palestine (mainly in a rural area) were examined. Among them,
10 plant species were among those with the highest mean cultural importance values, according to
an ethnobotanical survey that was conducted in the West Bank, Palestine, a few years ago. Method:
The protocol of the DPPH assay for testing free-radical scavenging was utilized for determining EC50
values, while microdilution tests were conducted to determine the 50% inhibitory concentration (IC50)
of the extracts for the microorganism Staphylococcus mutans. Results and Discussion: Eight extracts
(non-polar fractions) were found to possess an antibacterial IC50 of less than 20 ppm, such as
Foeniculum vulgare, Salvia palaestinafruticose, Micromeria fruticose, Trigonella foenum-graecum, Cichorium
pumilum jacq, Salvia hierosolymitana boiss, Ruta chalepensis, and Chrysanthemum coronarium. The polar
fractions possess higher antioxidant activity, while non-polar fraction possess higher antibacterial
activity. Looking at all the results together can deceive and lead to the conclusion that there is no
correlation between antibacterial activity against S. mutans and free radical scavenging (R2 equals
0.0538). However, in-depth analysis revealed that non-polar plant extracts with an EC50 of free radical
scavenging 100 ppm have a four-fold order of enrichment toward more activity against S. mutans.
These findings are of high importance for screening projects. A four-fold order of enrichment
could save plenty of time and many in screening projects. The antibacterial active extracts marked
by low-medium free radical scavenging might act through a mechanism of action other than that
of highly active, free radical scavenging extracts. Conclusion: The screening of antioxidant and
antimicrobial activity performed on 25 selected wild plant extracts revealed a satisfactory free radical
scavenging and antimicrobial potential that could be of value in the management of oxidative stress.
Further studies are recommended to explore novel and highly active natural antibacterial products.
Description
Keywords
radical scavenging activity , antioxidant , oxidative stress , wild edible plant , natural product