Chemical Composition, Enantiomeric Distribution and Anticholinesterase and Antioxidant Activity of the Essential Oil of Diplosthephium juniperinum

The aim of this study was to extract and identify the chemical compounds of Diplosthephium juniperinum essential oil (EO) from Ecuador and to assess its anticholinesterase and antioxidant properties. The EO chemical composition was determined by GC–MS. A total of 74 constituents of EO were identified, representing 97.27% in DB-5ms and 96.06% in HP-INNOWax of the total EO. The major constituents (>4.50%) identified were: α-pinene (21.52, 22.04%), geranyl acetate (10.54, 7.78%), silphiper-fol-5-ene (8.67, 7.38%), α-copaene (8.26, 8.18%), 7-epi-silphiperfol-5-ene (4.93, 5.95%), and germacrene D (4.91, 6.00%). Enantioselective analysis of the volatile fraction of D. juniperinum showed: (+)-α-pinene as a pure enantiomer and 5 pairs of enantiomeric compounds. Among them, (−)-β-Pinene and (−)-Germacrene D presented a high enantiomeric excess of 93.23 and 84.62%, respectively, while (−)-α-Thujene, (−)-Sabinene and (S)-4-Terpineol with a lower enantiomeric excess of 56.34, 47.84 and 43.11%, respectively. A moderate inhibitory effect was observed for Acetylcholinesterase (AChE) and Butyrylcholinesterase (BuChE) enzymes with IC(50) values of 67.20 ± 7.10 and 89.00 ± 9.90 µg/mL, respectively. A lower antioxidant potential was observed for the EO measured through DPPH and ABTS radical scavenging assays with SC(50) values of 127.03 and >1000 µg/mL, respectively. To the best of our knowledge, this is the first report of the chemical composition, enantiomeric distribution and, anticholinesterase and antioxidant potential of the EO of D. juniperinum. As future perspective, further in-vivo studies could be conducted to confirm the anticholinesterase potential of the EO.