Scientific African (Nov 2022)
Physicochemical characterisations of nanoencapsulated Eucalyptus globulus oil with gum Arabic and gum Arabic nanocapsule and their biocontrol effect on anthracnose disease of Syzygium malaccense Fruits
Abstract
Nanoencapsulated E. globulus oil (NP and NC) and gum Arabic (NNP and NC) were prepared using nanoprecipitation (NP and NNP) and nanocapsule elaboration (NC and NNC) methods. Gas chromatography and gas chromatography-mass spectrometry (GC/GC-MS) were used to analyse the oil used in this study. Dynamic light scattering (DLS), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), loading capacity (LC), and encapsulation efficiency (EE) were used to characterise the nanoencapsulated oil. In addition to characterisation, an in-vitro kinetics study of the nanoencapsulated oil was carried out. Fungi were also isolated from rotten S. malaccense, and the pathogenicity of the fungi was determined. Furthermore, the nanoencapsulated oil was used to determine the in-vitro and in-vivo control of anthracnose in the fruits. The GC/GC-MS analysis revealed that eucalyptol (63.81%) was the most abundant constituent of the Eucalyptus oil. The DLS revealed that the average particle size of NP (219±280.94nm) increased compared to NNP (51.8768.44nm), while the average particle size of NC (516±165.21nm) decreased compared to NNC (548±73.73nm). Similarly, the average particle size as measured by TEM followed the same pattern as DLS, NP (7.52±3.54nm), NNP (4.43±1.18nm), NC (6.24±2.13nm), and NNC (8.89±1.54nm). Furthermore, there were additional FTIR peaks with the incorporation of the oil (NP) via the nanoprecipitation method; however, there was no peak with the incorporation of the oil (NC) via the nanocapsule elaboration method. The oil's (NP and NC) incorporation with the gum Arabic's (NNP and NP) LC, EE, and in-vitro release were all affected. Fungi isolated from rotten S. malaccense fruits revealed the presence of Rhizopus stolonifer, Colletotrichum gloeosporioides, and Aspergillus niger; C. gloeosporioides was also confirmed to be the cause of the rot in S. malaccense fruits. The nanoencapsulated oil's antifungal activities indicated that it could be used to control anthracnose disease in S. malaccense fruits.
