Short Path Molecular Distillation of the Essential Oil from Pinus Roxburghii Oleoresin Affords Fractions with Valuable Antioxidant and Antimicrobial Activities Higher than the Parent Oil

Abstract

The main aim of this study was to obtain products with antioxidant and antimicrobial properties higher than the turpentine essential oil hydro distilled from Pinus roxburghii oleoresin. The distillation temperature affected the yield as well as the antioxidant and antimicrobial properties of the oil; the highest yield (20.27%) and activities were obtained for the oil distilled at 180 °C. This oil (EO1) was subsequently separated by short path molecular distillation in fractions and sub-fractions, which included a volatile mixture distilled in the range of 68-75 °C with the highest yields. The antioxidant activity of fractions and sub-fractions were then determined by the DPPH scavenging activity, the % inhibition of linoleic acid peroxidation, the FRAP assay/ total antioxidant contents, and the H2O2 assays. The antimicrobial activity against the bacteria Pasteurella multocida, Staphylococcus aureus, Escherichia coli, and Bacillus subtilis, and the fungal strains Fusarium solani, Alternaria alternate, Aspergillus flavus, and Aspergillus niger, were measured by the agar well diffusion method, the microdilution broth assay and the resazurin microtiter plate test. The antioxidant and antimicrobial activities varied between fractions and subfractions; however, their overall potency makes the P. roxburghii oleoresin a potential source of valuable natural antimicrobial products employable against various food borne microbes and molds, as well as a source of effective preservative agents against food oxidation. Longifolene, 3-carene, α-pinene and β-pinene were identified by GC-MS as the main constituents of the P. roxburghii turpentine essential oil and the most active fractions and sub-fractions. These terpenes were likely responsible for the activities of the volatile mixtures.

Keywords: Chir pine oleoresin, essential oil, Fractionation by molecular distillation, GC-MS, Antioxidant and antimicrobial activities