Advancement in Medicinal Plant Research

38-43

Authors: Guilherme Perez Pinheiro, Maria Isabel Galbiatti, Mara Junqueira Carneiro and Alexandra Christine Helena Frankland Sawaya

Plectranthus amboinicus, also known as Indian borage or Mexican mint, is a species of Lamiaceae cultivated worldwide for ornamental, culinary and medicinal purposes, being used in folk medicine for the treatment of respiratory diseases and digestive problems. These properties are attributed to the abundance of phenolic monoterpenes present in its essential oil, which have been extensively described in the literature. The low yield of essential oil hinders further investigation, besides the extraction being a costly and time-consuming procedure. The application of headspace-solid-phase microextraction (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS), an alternative technique in plant volatile analysis, is described in the present study for P. amboinicus growing in Brazil. Four SPME fibers with different coating composition were evaluated: polydimethylsiloxane (PDMS - 100 µm), carboxen/polydimethylsiloxane (CAR/PDMS - 75 µm), divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS - 50/30 µm) and polydimethylsiloxane/divinylbenzene (PDMS/DVB - 65 µm). PDMS fiber extracted a total of 19 identified compounds (52.46% of monoterpenes and 42.09% of sesquiterpenes), CAR/PDMS fiber 22 identified compounds (55.05% of monoterpenes and 25.51% of sesquiterpenes), DVB/CAR/PDMS fiber 24 identified compounds (67.22% of monoterpenes and 23.88% of sesquiterpenes) and PDMS/DVB fiber 26 identified compounds (64.3% of monoterpenes and 30.93% of sesquiterpenes). The extractions with PDMS/DVB and DVB/CAR/PDMS fibers resulted in similar chemical profiles when compared to essential oil composition, in particular the triple-coated DVB/CAR/PDMS fiber which extracted more compounds with high retention time. Both of these fibers are the most suitable in an untargeted analysis of P. amboinicus volatiles, while PDMS and CAR/PDMS may be suitable for target compounds or classes of compounds. The data reported in this study demonstrates that HS-SPME coupled to GC-MS is a rapid and simple method of analysis and compose a valuable tool for the study of P. amboinicus volatiles.

54-60

Authors: Jose Tapiero, Guillermo Salamanca and Carlos Marín

Aromatic plants make secondary metabolites that can be useful or toxic to an organism. In this work, we obtained Essential Oil (EO) by Microwave-assisted Hydrodistillation (MWHD). The process was carried out during the period from 15 min to 700 watts, with samples of 50, 100 and 200 g, collected in Vijes and Sevilla, Valle, Colombia. For each sample of essential oil the relative density at 20°C and the Refractive Index were evaluated (RI). The chemical composition was evaluated using GC-MS and its antiradical activity (AA) was carried out using the DPPH*, ABTS+ and ORAC methods. The process yield was between 0.087 ± 0.012 and 0.140 ± 0.005%. Significant differences were observed for the RI with values between 1.475 ± 0.001 and 1.484 ± 0.003 for a (Pv < 0.05). The highest contributions correspond to p-Cimeno (10.04), Terpinen-4-ol (9.48), Carvacrol (8.70%) and Thymol (1.95%) presented lowest values. The EO of oregano presents a good AA that ranges between 318.8 ± 0.009 to 320.6 ± 0.003 (Sevilla) and 310.8 ± 0.021 to 312.1 ± 0.014 (Vijes) mmol Trolox/100 g for DPPH*, and 23.852 ± 0.018 to 24.019 ± 0.011 (Sevilla) and 23.128 ± 0.012 to 23.412 ± 0.009 (Vijes) mmol Trolox/100g for ABTS+. Finally, oregano essential oils presented low molecular weight aliphatic compounds, being markers of these matrices.