Shweta, Gangasa (2021) Antiamoebic potential of Malaysian seaweeds based natural products and their conjugated nanoparticles. Masters thesis, Sunway University.
Full text not available from this repository.Abstract
Acanthamoeba spp. causes infections in the humans mainly Acanthamoeba keratitis (AK) and granulomatous amoebic encephalitis (GAE). Currently, the treatment options are limited and highly toxic as per the recommended dosages. The current available therapeutic drugs are either ineffective against one or both stages in the life cycle of Acanthamoeba which are trophozoite and cyst or have high host cells cytotoxicity. Therefore, there is an urgent need to develop cheaper and effective antimicrobial agents from natural resources, having fewer side effects, minimal or no toxicity and which can cross blood brain barrier. In recent development, various natural products from plant origin have been mainly used for treatment of infectious diseases as the bioactive metabolites from these products have shown antiacanthamoebic activity. Recently, researchers have been using nanoparticles as a drug carrier to improve the efficacy where in recent studies drugs loaded with silver nanoparticles have exhibited great antiacanthamoebic potential in vitro. Nowadays, research on natural products from marine environment have showcased potent antibacterial, antifungal, and antiprotozoal activity. One such natural products from marine life are the seaweeds which produce many secondary metabolites in the aid to protect themselves from environmental stress. The bioactive components of seaweeds possess a variety of polysaccharides, fatty acids, tannins, alkaloids, terpenoids, pigments, lectins and halogenated compounds which have potent antimicrobial properties. However, seaweeds have not been much harnessed for their potential antiacanthamoebic properties. In this study, we have focused on multiple Malaysian cultivated seaweeds, belonging to the red and brown algae family namely, Kappaphycus alvarezii, Kappaphycus malesianus, Sargassum polycystum and Turbinaria spp. The crude extraction was carried out using two organic solvents namely ethanol and methanol. The crude extracts were subjected to liquid chromatography and mass spectroscopy to identify the bioactive metabolites like Fucoxanthin, C16 Sphingonine, Dulciol B, Xestoaminol C, Oleamide, Prosphonine, Stigmatellin Y, Lucidumol A, 2-Hydroxyhexadecanoic acid etc. Further, the crude extracts were conjugated with silver nanoparticles to enhance the efficacy of the extracts. Later, the synthesized silver nanoparticles were characterized by UV-vis spectrophotometry, Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and particle sizer. Extracts conjugated with silver nanoparticles (AgNPs) showed the surface plasmon resonance band at 418 and 408 nm for K. alaverezii ethanol extracts and methanol, 416 and 411 nm for K. malesianus ethanol and methanol extracts respectively, whereas for brown algae the peaks were observed at 418 and 416 nm for S. polycystum ethanol and methanol extracts, 417 and 418 nm for Turbinaria spp. ethanol and methanol extracts which denotes to the successful formation of extract conjugated AgNPs. FTIR results revealed the presence of many functional groups which might be responsible for the interaction and stabilization of the extract-nanoconjugates. The TEM results exhibited spherical shape of the nanoparticles and did not show any agglomeration of the particles. The anti-Acanthamoeba assays revealed that the extracts conjugated with AgNPs have reduced the viability of the amoeba when compared to the amoeba treated with extracts alone. All the extracts alone were able to inhibit the excystation and encystation process as well when tested at 25 and 50 μg/ml concentrations. In amoebicidal assay, the IC50 for both the red algae nanoconjugates was achieved at the concentration of 50 μg/ml where it inhibited the trophozoites by approx. 51% as compared to the untreated amoeba. Furthermore, in brown algae, S. polycystum nanoconjugates were able to inhibit the trophozoites by approx. 87% at 50 μg/ml, whereas Turbinaria spp. methanol nanoconjugate was able to decrease the viability by approx. 77% and ethanol nanoconjugates lowered the viability by approx. 88% at highest concentration. Moreover, all the extracts and nanoconjugates did not exhibit any toxicity towards human keratinized cells in vitro. The mechanism of cell death was analyzed by the measurement of ROS using dichlorofluorescein. The production of ROS was greater in nanoconjugates as compared to the amoeba treated extracts alone where methanol nanoconjugates showed highest ROS production in red algae as that of ethanol extract conjugates, on the other hand, both solvent extract conjugates showed similar ROS production in brown algae. Furthermore, the morphological studies of treated amoeba were analyzed by FESEM where it was revealed that the untreated amoeba showed regular amoeboid shape with integrated cell wall with acanthpodia, comparatively, the treated amoeba showed disintegrated and irregular cell wall and rounding off the cell. Amoeba treated with brown algae extract conjugate showed blebbing of the plasma membrane. Thus, it can be anticipated that the seaweed based natural products could be topic of interest in research for the development of alternative therapeutic agents against the infectious diseases caused by Acanthamoeba.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | antiamoebic; seaweeds; nanoparticles; algae; acanthamoeba. |
| Subjects: | Q Science > QK Botany R Medicine > RE Ophthalmology R Medicine > RS Pharmacy and materia medica |
| Divisions: | Sunway University > School of Medical and Life Sciences [formerly School of Healthcare and Medical Sciences until 2020] > Dept. Biological Sciences |
| Depositing User: | Ms Yong Yee Chan |
| Date Deposited: | 06 Oct 2023 01:18 |
| Last Modified: | 06 Oct 2023 01:18 |
| URI: | http://eprints.sunway.edu.my/id/eprint/2437 |
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