Antioxidant, Antimicrobial, and Antibiofilm properties of Opuntia stricta and Vachellia erioloba, and chemical characterization of volatile compounds

Vachellia erioloba, commonly known as Acacia erioloba belongs to the family Fabaceae and is native to Namibia, Botswana, and South Africa. The plant is used traditionally to treat ear infections, headaches, and toothaches. Opuntia stricta belongs to the family Cactaceae and is found in Namibia. The plant is used in the management of diseases such as diabetes, obesity, and cancer. This study was designed to investigate the antioxidant, antimicrobial, antibiofilm activity, and chemical characterization of V. erioloba and O. stricta. The radical scavenging capacity of extracts was estimated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the reducing power was determined using ferric reducing power assay. Moreover, the antimicrobial activities of the extracts of these medicinal plants were tested against Staphylococcus aureus, Streptococcus mutans, Escherichia coli, and Candida albicans. On the other hand, antibiofilm activity was determined against Staphylococcus aureus. The phytochemical analysis of V. erioloba and O. stricta was done using qualitative and quantitative phytochemical analysis. Moreover, the characterization of the volatile constituents was done for the seed extract of V. erioloba. Furthermore, chemical characterization of the volatile constituents of the extract was performed using gas chromatography-mass spectrometry (GC–MS). The radical scavenging assay revealed IC50 values of 1.973 ± 0.012 and 972.0 ± 22.3 μg/mL for the seed pods and seed of V. erioloba, respectively, while the IC50 values for the extracts of O. stricta were 53.74 ± 0.18, 153.8 ± 0.9, 258.7 ± 0.7, and IC50 ˃ 1000 μg/mL for the seeds, flowers, fruits, and leaves of O. stricta, respectively. In addition, the reducing power of both V. erioloba and O. stricta extracts increased as the concentration of the extracts increased, which confirmed the presence of antioxidants in the extracts. The antimicrobial assay revealed that the various extracts of V. erioloba and O. stricta ii exhibited moderate antimicrobial activity with inhibition zones (IZ) ranging from 0 to 12 mm. Moreover, the MIC obtained from this study ranged from ≤ 0.63 to 10 mg/mL. The biofilm inhibition demonstrated BIC50 values of V. erioloba and O. stricta extracts ranged from ˂ 0.08 to 0.498 ± 0.017 mg/mL. Moreover, biofilm eradication revealed BEC50 values ranged from < 0.08 to 0.172 ± 0.008 mg/mL. The GC-MS analysis of V. erioloba seed extracts revealed the presence of phytosterols, acids, esters, α- tocopherol and α-amyrin, which comprises a number of known bioactive compounds. The results from this study show that V. erioloba and O. stricta extracts possess antioxidant, antimicrobial, and antibiofilm properties, making these plants good potential sources of antioxidants and antimicrobial agents. The findings of this study support the traditional uses of V. erioloba and O. stricta.

Grantor dc:publisher

University of Namibia

Year dc:date.issued

2023

Author dc:creator

• Jackson, Junias Natangwe

Advisor dc:contributor.advisor

• Kapewangolo, Petrina

• Traditional uses
• Biofilm inhibition
• Biofilm eradication
• 2-diphenyl-1- picrylhydrazyl (DPPH)
• Gas chromatography-mass spectrometry (GC–MS)
• Namibia
• University of Namibia

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/11070/3965

OAI identifier oai:identifier

oai:repository.unam.edu.na:11070/3965