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Abstract
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Recently, the emergence and spread of pathogenic bacterial resistance to many synthetic
antibiotics have been increasing throughout the world. This phenomenon is of great concern
and there is a need to find new compounds as an appropriate alternative to antibiotics. In this
regard, natural antibiotics derived from medicinal plants, some of which have been used in
traditional medicine for centuries and have competitive effects compared to some commercial
antibiotics, can be studied as alternatives [1-2]. In this study, the antibacterial and antioxidant
activities as well as total phenol and flavonoid contents were assayed in the ethanolic extracts
obtained by ultrasound-assisted extraction method (UAE) from Terminalia chebula, Rosa
canina, and Nigella sativa. The ethanolic extracts were screened against two gram-negative
(Escherichia coli ATCC25922 and Pseudomonas aeruginosa ATCC27853( and two gram-
positive (Bacillus cereus ATCC11778 and Bacillus subtilis ATCC6633) bacteria with the disk
diffusion method. The highest antibacterial potentiality was exhibited by the ethanolic extract
of N. sativa against E. coli (16.5 mm). The ethanolic extracts were assessed for their
antioxidant activity using DPPH radical scavenging assay. According to the results, the
highest antioxidant activity related to T. chebula with the percentage inhibitory of 80.66%.
Also, ethanolic extract of T. chebula (140.53 mg GAE/ g plant) showed the highest phenolic
content. The highest amount of total flavonoid content was observed in N. sativa extract
(11.88 mg QE/g plant). So, T. chebula can be used in food, medicine, and cosmetic industries.
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