In vitro antifungal activity of four chemotypes of Lippia alba (Verbenaceae) essential oils against Alternaria solani (Pleosporeaceae) isolates

Abstract

Several volatile natural compounds produced by plant secondary metabolism have been proven to present antimicrobial action, enabling their use in phytopathogen control. They also present low environmental impact when compared to conventional pesticides. Essential oils contain these compounds and can be found in several plant species, such as Lippia alba (Mill.) N.E. Brown (Verbenaceae). Essential oils of four chemotypes of L. alba, characterized by their major compounds, namely camphor, citral, linalool and camphor/1,8-cineole, were tested against the phytopathogen Alternaria solani Sorauer (Pleosporaceae), which causes early blight on tomatoes and is responsible for great economic losses regarding production. Essential oils antifungal action was tested in vitro using potato dextrose agar medium with essential oil concentrations at 0.1, 0.5, 1.0, 1.5 and 2.0 μL mL -1 . The chemotype that had the best performance was citral, showing signifi cant inhibition compared to the others, starting at the 0.5 μL mL -1 concentration. The essential oil belonging to the linalool chemotype was effi cient starting at the 1.5 μL mL -1 concentration.Conversely, the camphor chemotype did not show any action against the phytopathogen. Moreover, the essential oils had no remarkable effect on tomato germination and growth. In conclusion, these essential oils presented fungicidal action against A. solani.

Anxiolytic-like effect of Lippia alba essential oil: A randomized, placebo-controlled trial

“…The system conditions were the following: fused silica capillary column HP-Innowax (30 m x 0.25 mm i.d., 0.25 µm film thickness), column temperature, 40°C (8 minutes) to 180°C at 3°C/min, 180-230°C at 20°C/min, 230°C (20 minutes); interface 280°C; split ratio 1:100; carrier gas He (56 KPa); EI mode 70 eV. Finally, the identification of essential oil constituents was accomplished by visual interpretation, comparing their retention indices and mass spectra with the literature data and with those in the NIST 2011 mass spectra library as well as Wiley library [17].…”

“…Its essential oil has several chemotypes depending on the geographic location and the characteristics of the soil and climate [14,15]. Different laboratories have determined the antibacterial [16], antifungal [17], anesthetics [18], and anxiolytic [19] effects of L. alba EOs.…”

Control of Postharvest Fungal Rots on Grapes Using Essential Oil of Foeniculum vulgare Mill.

“…For identification and quantification of compounds of the essential oil, it was used the protocol described in Tomazoni et al (2016) using a gas chromatograph HP 6890, coupled with a mass selective detector Hewlett Packard MSD5973, equipped with HP Chemstation software and Wiley 275 spectra data. The analyses were conducted using a fused silica capillary column HP-Innowax (30 m × 0.25 mm i.d., 0.25 µm film thickness, Hewlett Packard, Palo Alto, USA).…”

Cytotoxic and Antimicrobial Constituents from the Essential Oil of Lippia alba (Verbenaceae)

“…However, future studies with purified fractions from this oil could uncover more significant biological activities against bacteria, as shown before by Klein et al [39]. Essential oils from L. alba have been extensively reported as antifungal, especially against phyto [40,41,42,43] and human pathogens [43]. In summary, these results hold a promise of possible applications for L. alba essential oil as an antifungal in medicine, as well as in agriculture.…”