Bioprospecting for active compounds: impact of milling, extract fractions and freeze-drying on targeted terpene compounds of Helichrysum odoratissimum (L.) Sweet

Abstract

This study investigated the effect of processing and freeze-drying on targeted volatile compounds (terpenes) of Helichrysum odoratissimum (L.) Sweet. Air-dried plant material was processed to obtain: (i) roughly ground leaves and stems (RGMHO); (ii) finely ground leaves and stems (FGMHO); and (iii) wool-like fraction (WLMHO). Terpene content of the air-dried samples, crude ethanol extract (CE, filtrate), sediments and freeze-dried (FDE) powders from the different processed fractions were analysed using gas chromatography-mass spectrometry (GC-MS). Results showed that the highest α-pinene (91.3 µg l⁻¹) was obtained in the CE compared to the freeze-dried (≈3.0 µg l⁻¹) extracts (p ≤ 0.05). Eucalyptol was significantly higher in the air-dried leaves (27.3 µg l⁻¹) than were CE and FDE (4.0 and 0.9 µg l⁻¹ respectively), while β-caryophyllene, pulegone and humulene contents were significantly higher in the FDE samples (p ≤ 0.05). These results demonstrated that processing had significant impact on the concentration of targeted terpenes in H. odoratissimum. This study is the first report on the identification and quantification targeted terpenes in H. odoratissimum (L.) Sweet.