Synthesis and characterization of gold nanoparticles biosynthesised from Aspalathus linearis (Burm.f.) R.Dahlgren For progressive macular hypomelanosis

Abstract

IntroductionThe study investigated a natural solution for the hypopigmentary disorder, progressive macular hypomelanosis (PMH). The aim was to determine whether gold nanoparticles synthesized from Aspalathus linearis (Burm.f.) R.Dahlgren could be effective for PMH. MethodsGold nanoparticles (ALAuNPs) were synthesized using the ethanolic extract of A. linearis (ALEtOH) and tested, along with the extract for its regulatory effect of melanogenesis in human melanocytes and its antibacterial activity against Cutibacterium acnes (ATCC 6919 strain). Melanosome transfer was determined in a co-culture of normal human melanocytes and keratinocytes and was quantified using flow cytometry. ResultsThe ALAuNPstab (AuNPs stabilized with gum arabic) and ALAuNPnon-stab (non-stabilized) exhibited significantly (P < 0.001) higher antibacterial activity against C. acnes with 50 % inhibition at a concentration of 66.05 ± 1.10 μg/mL and 68.12 ± 1.05 μg/mL, respectively, as compared to that of ALEtOH (271.20 ± 2.32 μg/mL). The ALEtOH exhibited 50 % reduction in cell proliferation (IC50 value) in human melanocytes at 345.5 ± 2.47 μg/mL, whilst ALAuNPstab and ALAuNPnon-stab exhibited an IC50 value of 67.51 ± 1.12 and 69.63 ± 1.07 μg/mL, respectively. The ALEtOH and ALAuNPstab tested at a concentration of 62.5 μg/mL, exhibited a significant increase (P < 0.001) in the total number of melanin present in human melanocytes compared to the untreated (control) cells. The cells treated with ALEtOH and ALAuNPstab led to a significant (P < 0.001) increase in the number of melanosomes transferred as compared to the untreated cells. ConclusionThis study confirmed that A. linearis and its biosynthesised gold nanoparticles stimulated melanin synthesis.