Chemical composition analysis and biological activities of essential oil from Eucalyptus polybractea (L.), growing in plains of Punjab, Northern India, by two different hydro-distillation methods

Abstract

Eucalyptus essential oil poses various biological activities due to the presence of various bioactive compounds. The objective of this study was to evaluate the effect of direct heat-based hydro distillation (DHBH) and in-direct heat-based hydro-distillation (IDHBH) methods on chemical profile, extraction, and biological activities of essential oils from Eucalyptus polybractea. Eucalyptus Essential Oil (EEO) was extracted from green leaves of eucalyptus plant using DHBH and IDHBH methods. Aroma profile was evaluated by GC-FID technique. Content of phenolics, flavonoids and tannins accompanied by antioxidant activities like iron-chelation and DPPH were studied. Other biological activities like anti-inflammatory and anti-microbial were also analysed. GC-FID chemical profiling revealed a greater number of bioactive compounds in IDHBH extract than DHBH. Relationship between antioxidant activity and chemical composition of extracted oils was investigated. Significant amount of β- pinene, 1,8 cineole, eugenol, Pentadecanoic acid are responsible for antioxidative capacity of both extracts. The concentration of all compounds, especially Pentadecanoic acid and other unique bioactives were higher in IDHBH extract. The level of antioxidants like phenolics, flavonoids and tannins by was high also high in IDHBH extracted oil. This corresponds to higher antioxidant activities like DPPH and iron-chelating activity of IDHBH oil compared with DHBH extract. Similarly, anti-inflammatory, and anti-microbial potential was more in oil extracted with IDHBH than DHBH. The present paper reported that different extraction methods lead to different biochemical composition of essential oils and the choice of a suitable method is extremely important to obtain more preferred compounds with more potent biological activities and this method can be the choice for essential oil-based companies.