Browsing by Author "Adewale, Olusola B."

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    Biological synthesis of gold and silver nanoparticles using leaf extracts of Crassocephalum rubens and their comparative in vitro antioxidant activities
    (Elsevier, 2020) Adewale, Olusola B.; Egbeyemi, Kayode A.; Fadaka, Adewale O.
    The use of plant and plant products in the synthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) is made possible because of the natural inherent phytochemicals responsible for the reduction of respective metallic salts to nanoparticle forms, and ensuring therapeutic applicability. In this study, synthesis of AgNPs and AuNPs was performed using two different aqueous extraction methods for Crassocephalum rubens: maceration using laboratory method of extraction (cold aqueous extract of Crassocephalum rubens (AECR)), and decoction using traditional healer's method of extraction (hot aqueous crude extract of Crassocephalum rubens (CECR)). The synthesized nanoparticles were characterized using various methods, and in vitro antioxidant po- tential were thereafter investigated. The characterization results indicated the formation of mostly spherical- shaped AgNPs and AuNPs with surface plasmon resonance (SPR) band of 470 nm and 540 nm, respectively. The nanoparticles possess high antioxidant potentials but AECR synthesized AuNPs exhibited the least phyto- chemical contents and antioxidant potential when compared to other nanoparticles. It can therefore be concluded that extraction method and nanoparticle type are important factors that could influence the antioxidant properties of the nanoparticles. Further studies using these nanoparticles as anticancer or anti-inflammatory agent in both in vitro and in vivo are underway.
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    One-pot synthesis, characterisation and biological activities of gold nanoparticles prepared using aqueous seed extract of Garcinia kola
    (2023-02) Sibuyi, Nicole R.S.; Fadaka, Adewale O.; Anadozie, Scholastica O.; Adewale, Olusola B.; Isitua, Chinwe C.; Davids, Hajierah; Roux, Saartjie
    Recently, biogenic synthesis of gold nanoparticles (AuNPs) has become a focus area in cancer research owing to the eco-friendliness and cost effectiveness of the synthetic method. In this study, aqueous extract of Garcinia kola seed (AEGKs) was used for the bio-reduction of Au3+ to Au0. The synthesised AEGKs-AuNPs was characterised by ultraviolet-visible (UV-Vis) spectroscopy, dynamic light scattering (DLS), high-resolution transmission electron microscopy (HRTEM) and Fourier transform-infrared (FT-IR) spectroscopy. The in vitro antioxidant activity of the AEGKs and AEGKs-AuNPs was evaluated using 2,2-diphenyl-1-picrylhydrazyl radical scavenging ability and ferric reducing antioxidant power assays. The AEGKs-AuNPs showed an absorption maximum at 512 nm, and the HRTEM images revealed mostly, spherical-shaped AuNPs in the size range of 2–17 nm. The FT-IR spectroscopy revealed that polyphenolic compounds and proteins were predominant, and responsible for the reduction and capping of the AuNPs. The AEGKs-AuNPs showed concentration dependent antioxidant activities, while dose dependent in vitro anti-cancer activity of the AEGKs-AuNPs was demonstrated against lungs, prostrate, human cervical and human colon cancer cells, using the 3-(4,5-dimethylthiazol-2-yl)− 2,5-diphenyltetrazolium bromide tetrazolium reduction (MTT) assay. The antioxidant and anti-cancer activities of the AEGKs-AuNPs could be attributed to the presence of phytochemicals and physicochemical properties of the AuNPs.