Browsing by Author "De Koning, Charles B."

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    In vitro analysis of the combinatory effects of novel aminonaphthoquinone derivatives and curcumin on breast cancer progression
    (International Institute of Anticancer Research, 2020-01) Pereira, Melanie C.; Mohammed, Raushaan; Van Otterlo, Willem A. L.; De Koning, Charles B.; Davids, Hajierah
    Background/aim: We previously reported the potential of aminonaphthoquinone derivatives as therapeutic agents against breast and other oestrogen-responsive tumours when combined with curcumin. This study aimed at screening of novel aminonaphthoquinone derivatives (Rau 008, Rau 010, Rau 015 and Rau 018) combined with curcumin for cytotoxic, anti-angiogenic and anti-metastatic effects on MCF-7 and MDA-MB-231 breast cancer cells. Materials and methods: Cytotoxic and anti-angiogenic effects were analysed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and enzyme-linked immunosorbent assay; while anti-metastatic effects were measured using adhesion assay, Boyden chambers and Matrigel. Results: Curcumin combined with Rau 008 elicited marked cytotoxic effects in MCF-7 cells compared with the individual treatments, whereas when it was combined with Rau 015 and with Rau 018, it displayed similar effects in MDA-MB-231 cells. The anti-angiogenic effect of Rau 015 plus curcumin in MCF-7 cells and Rau 018 plus curcumin in MDA-MB-231 cells was more effective than individual treatments, while the metastatic capability of MDA-MB-231 cells was significantly reduced after treatment with the aminonaphthoquinone-curcumin combinations. Conclusion: Aminonaphthoquinones may offer significant promise as therapeutic agents against breast cancer, particularly when combined with curcumin.
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    Synthesis and antimicrobial activity of the essential oil compounds (E)- and (Z)-3-hexenyl nonanoate and two analogues
    (University of KwaZulu-Natal, 2012) Chakravorty, Santanu; Rayner, Matthew K.; De Koning, Charles B.; Van Vuuren, Sandy F.; Van Otterlo, Willem A. L.
    The synthesis of (E)- and (Z)-3-hexenyl nonanoate, known constituents of essential oil containing plants, and two related compounds is reported. These compounds were assembled from nonanoyl chloride or nonanoic acid and the respective alcohols. In particular, it was found that the use of triethylamine as a co-solvent was necessary to avoid acid-mediated isomerization of the alkenes, which resulted in an inseparable mixture of products. The antimicrobial activity of the four hexenyl and hexyl nonanoate compounds was undertaken using microdilution minimum inhibitory concentration (MIC) analysis against eight test microorganisms. All four compounds demonstrated activity, with (E)-3-hexenyl nonanoate 1B: having the highest inhibition (MIC value of 0.45 mg mL-1) against Pseudomonas aeruginosa ATCC 27858. Furthermore, this compound demonstrated the highest broad-spectrum activity (mean MIC value of 1.24 ± 0.50 mg mL-1) with noteworthy activity against all pathogens tested.