Facile Fabrication of α-Bisabolol Nanoparticles with Improved Antioxidant and Antibacterial Effects

Abstract

Bioactive compounds are widely used in the bio-industry because of their antioxidant and antibacterial activities. Because of excessive oxidative stress, which causes various diseases in humans, and because preservatives used in bioproducts cause allergies and contact dermatitis, it is important to use natural bioactive compounds in bioproducts to minimize oxidative stress. α-bisabolol (ABS) is a natural compound with both antioxidant and antibacterial properties. However, its water-insolubility makes its utilization in bioproducts difficult. In this study, ABS-loaded polyglyceryl-4 caprate nanoparticles (ABS@NPs) with improved aqueous stability and ABS loading were fabricated using an encapsulation method. The long-term stability of the ABS@NPs was analyzed with dynamic light scattering and methylene blue-staining to determine the optimized ABS concentration in ABS@NPs (10 wt%). The ABS@NPs exhibited excellent antioxidant activity, according to the 2,2-diphenyl-1-picrylhydrazyl assay and in vitro reactive oxygen species generation in NIH-3T3 fibroblast cells, and an outstanding antibacterial effect, as determined using the Staphylococcus aureus colony-counting method. Furthermore, we evaluated the biocompatibility of the ABS@NPs in vitro. This study suggests that ABS@NPs with improved antioxidant and antibacterial properties can be used to treat diseases related to various oxidative stresses and can be applied in many fields, such as pharmaceuticals, cosmetics, and foods.

Keywords: antibacterial; antioxidant; bioactive compound; encapsulation; nanoparticle; polyglyceryl-4 caprate; solubilization; α-bisabolol.

Figure 1

Schematic illustration of the preparation of α -bisabolol-loaded nanoparticles (ABS@NPs) and improved antioxidant and antibacterial effects.

Figure 2

(A) Particle size, (B) polydispersity index (PDI), and (C) zeta potential of ABS@NPs with different ABS loadings in the range of 0 to 40 wt%. (D) Methylene blue staining test of the ABS@NPs with different ABS loadings.

Figure 3

Long-term stability of ABS@NPs at ABS concentrations ranging from 0 to 40 wt%. Variation of the (A) particle size and (B) polydispersity index (PDI) of ABS@NPs over 112 days.

Figure 4

(A) Antioxidation activity of ABS@NPs with 0, 5, and 10 wt% ABS, compared to that of ascorbic acid (AA) in deionized water (DIW), assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay. (B) Results of in vitro assays using the H2DCFDA assay kit. Antioxidation activity of ABS@NP 10 wt% at ABS concentrations ranging from 1 to 1000 nM; reactive oxygen species (ROS) and the control (CTL) groups represent the highest and lowest levels of ROS, respectively (* p < 0.05, ** p < 0.01, *** p < 0.005).

Figure 5

Antibacterial activity of ABS@NPs. (A) Photographs of staphylococcus aureus ATCC 6538 colonies in (i) phosphate-buffered saline, (ii) ABS in deionized water (DIW), (iii) ABS@NP 0 wt% in DIW, and (iv) ABS@NP 10 wt% in DIW. (B) Viability of S. aureus after treatment with phosphate-buffered saline (PBS), ABS in DIW, ABS@NP 0 wt% in DIW, and ABS@NP 10 wt% in DIW.

Figure 6

Cytotoxicity analysis of 10 wt% ABS@NPs at ABS concentrations in the range of 1 to 10 μM (* p < 0.05).