Medicinal properties of Saudi Arabian flora extracts

Yonbawi, Ahmed 2022. Medicinal properties of Saudi Arabian flora extracts. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Infectious diseases account for increasing levels of mortality around the world. When microorganisms overcome epithelia barriers and immunological bodily defensive mechanisms of the skin, they can cause soft-tissue infections (SSTIs). This project explores the medicinal properties of five plants indigenous to the western region of Saudi Arabia, with a history of folkloric use: Aizoon canariense L. (Aizoaceae), Citrullus colocynthis (L.) Schrad. (Cucurbitaceae), Maerua crassifolia Forssk. (Capparaceae), Rhazya stricta Decne. (Apocynaceae), and Tribulus macropterus Boiss. (Zygophyllaceae), focusing on treating SSTIs and chronic wounds. An additional aim was to identify compounds to treat infections by following a bio-guided fractionation approach. Following a field trip, the target plants were collected and identified before undergoing methanolic extraction to yield approximately 200g of residual material. Initially, these extracts were evaluated for their effect on immortalized human skin keratinocytes (HaCaT) cell line proliferation, migration, and cytotoxicity through MTT, scratch wound, and flow cytometry. Confocal microscopy (CLSM) was utilized to confirm the morphology and viability of the cells. Antioxidant effects were determined using the acellular 1,1-Diphenyl-2-picrylhydrazyl (DPPH) method, and a cell-based method was utilized to measure a reactive oxygen species (ROS) level, namely hydrogen peroxide level (H₂O₂) in cell culture settings (ROS-Glo H₂O₂ assay). Antimicrobial properties were investigated by well diffusion, broth microdilution, and direct bio-autographic methods. The ability of medicinal plants to inhibit and eradicate bacterial biofilm was investigated by crystal violet and Live/Dead microbial viability method using CLSM. Plants that exhibited interesting antimicrobial activities were subjected to bioguided fractionation with liquid-liquid partitioning and column chromatography to identify and isolate active compounds. The anti-inflammatory effects of plant extracts were evaluated by utilising LPS-stimulated HaCaT cells to determine effects on expression of a panel of inflammatory mediators. Results indicated that C. colocynthis possesses cytotoxic activity with significant inhibition of proliferation and migration of human skin keratinocytes. On the other hand, M. crassifolia promoted the wound healing potential of HaCaT by stimulating the proliferation and migration. A. canariense and T. macropterus demonstrated antimicrobial activity against Gram-positive strains in planktonic and biofilm conditions. R. stricta demonstrated broadspectrum antimicrobial properties in planktonic and biofilm conditions against Gram-positive and negative bacterial species associated with SSTIs. The free radical scavenging data showed that both R. stricta and M. crassifolia gave the highest capacity for scavenging the DPPH radical with an IC50 of 335 and 448 μg/mL, respectively. In addition, R. stricta showed the highest H₂O₂ scavenging activity in the cell-based antioxidant method. Bio-guided fractionating of A. canariense and R. stricta successfully isolated γ-linolenic acid and v vincadifformine; further antimicrobial investigation with broth microdilution assay revealed these two compounds' contribution to the antimicrobial activity of the whole plant extract. However, this approach failed to identify and isolate the antimicrobial compounds detected via direct bio-autographic assay in T. macropterus. The anti-inflammatory investigation revealed that a number of plant extracts can decrease the protein levels of several inflammatory mediators. Finally, our study supports some of the documented ethnobotanical uses.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Pharmacy
Subjects:	Q Science > Q Science (General)
Date of First Compliant Deposit:	28 February 2023
Last Modified:	28 Feb 2023 11:42
URI:	https://orca.cardiff.ac.uk/id/eprint/157384

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