Peter Cavazos

Publication Date

7-16-2021

Document Type

Thesis

Degree Name

Master of Science in Biology (MS)

Committee Member

Mendez, Monica O.

Committee Member

Eversole, Cord

Committee Member

Addo-Mensah, Alfred K.

Abstract

The emergence and spread of antibiotic resistance, as well as the evolution of new strains are of great concern to the global health community. The search for novel agents to combat the rapid evolution of bacterial pathogens becomes ever more important as current methods are proving ineffective. In the present study, the different solvent extracts (acetone, methanol, and acetic acid) of Acacia berlandieri and Acacia rigidula (leaves) were evaluated for phytochemical analysis, antimicrobial and antioxidant activities. Plant leaves of Acacia rigidula and Acacia berlandieri were sequentially extracted using acetone, methanol and acetic acid that were then subjected to susceptibility testing against nine microorganisms. A qualitative phytochemical study was conducted to determine secondary metabolites of plant extracts. Extracts were analyzed using nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), and ultraviolet-visible spectroscopy (UV-Vis) to identify different substances within a test sample. Antioxidant activity was determined in Acacia rigidula using the FTC method. Results: This study provided evidence of antimicrobial activity from the crude extracts of both species, with an activity higher from the leaves of species A. rigidula. Among the nine microorganisms, two gram-negative (Providencia alcalifaciens and Yersinia enterocolitica) and two gram-positive (Staphylococcus aureus and Enterococcus faecalis) bacteria were susceptible. Qualitative phytochemical testing revealed important secondary metabolites: phenols, flavonoids, saponins, terpenoids and tannins. Each of which have been shown to possess antimicrobial properties and exert different modes of action. NMR, IR, and UV-Vis spectroscopy revealed the basic structures within our unknown samples that are commonly found in flavonoids, saponins, and tannins, reinforcing the results of phytochemical testing. Results revealed antioxidant activity within selected A. rigidula extracts. Analysis of the leaves extracts of A. berlandieri and A. rigidula have revealed the presence of medicinally valued bioactive components. This study confirmed the efficacy of selected plant extracts as natural antimicrobials and suggest the possibility of employing them in drugs for the treatment of infectious diseases caused by the test organisms.

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