Browsing by Author "Sibuyi, Nicole R.S"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Chitosan-coated liposomes of Carissa spinarum extract: synthesis, analysis and antipneumococcal potency
    (ICE Publishing, 2023) Rubaka, Clarence; Sibuyi, Nicole R.S; Gathirwa, Jeremiah Waweru
    In the present study, a chitosan-coatedCarissa spinarum-polyphenol-loaded liposome (LipCsP-chitosan) nanocarrierwas fabricated for the delivery ofC. spinarumpolyphenols (CsPs) to improve the bioavailability andantipneumococcal potential of CsPs againstKlebsiella pneumoniae. LipCsP-chitosan was synthesized using the iongelation method and characterized by using a Malvern Zetasizer and Fourier transform infrared (FTIR) spectroscopy.CsP encapsulation and release kinetics were investigated. The antipneumococcal activity of the nanoformulationswas assessed using agar-well diffusion and microdilution assays. LipCsP-chitosan exhibited a hydrodynamic size anda zeta potential of 365.22 ± 0.70 nm and +39.30 ± 0.61 mV, respectively. The encapsulation efficiency of LipCsP-chitosan was 81.5%. FTIR analysis revealed interactions of the liposomes with chitosan and CsPs. A biphasic CsPrelease profile followed by a sustained-release pattern was observed. LipCsP-chitosan presented a higherbioaccessibility of polyphenols in the simulated gastric phase (74.1 ± 1.3%) than in the simulated intestinal phase(63.32 ± 1.00%). LipCsP-chitosan had a relative inhibition zone diameter of 84.33 ± 2.51% when compared with CsPs.At a minimum inhibitory concentration of 31.25 mg/ml, LipCsP-chitosan reduced the viability ofK. pneumoniaeby57.45 ± 3.76% after 24 h. The results obtained from this study offer a new approach to the utilization of LipCsP-chitosan as nanocarriers for candidate antipneumococcal agents.
  • Thumbnail Image
    Item
    Design and synthesis of acyldepsipeptide-1 analogues: antibacterial activity and cytotoxicity screening
    (Arabian Journal of Chemistry, 2023) Sibuyi, Nicole R.S; Cobongela, Sinazo Z.Z; Makatini, Maya M
    Acyldepsipeptides (ADEPs) are receiving more attention as prospective antimicrobial agents due to their unique mode of action and chemical properties. However, their therapeutic potential is limited by their poor pharmacokinetic properties. Chemical modifications have been successful in improving the biocompatibility and bioavailability of ADEPs. In the current study, ADEP1 was modified by introducing a disulphide linkage, replacement of the octa-2,4,6-trienoic acid (OTEA) with either adamantane (Ada) or palmitic acid (Pal), and lastly, comparing the use of D versus L amino acids. The antibacterial effects of the ADEP1 analogues were investigated in Gram-positive and Gram-negative strains using agar well diffusion and microdilution assays. Cytotoxicity was evaluated in human embryonic kidney (HEK)-293 and colon cancer (Caco-2) cells by the MTS assay. Using solid phase peptide synthesis (SPPS), the percentage yield of the synthetic peptides was increased to > 37% with > 96% purity.