Phytotoxicity and Cytotoxicity of Essential Oil from Leaves of Plectranthus amboinicus, Carvacrol, and Thymol in Plant Bioassays

Abstract

The essential oil of Plectranthus amboinicus and its chemotypes, carvacrol and thymol, were evaluated on the germination and root and aerial growth of Lactuca sativa and Sorghum bicolor and in acting on the cell cycle of meristematic root cells of L. sativa. The main component found in the oil by analysis in gas chromatography-mass spectrometry and gas chromatography flame ionization detection was carvacrol (88.61% in area). At a concentration of 0.120% (w v(-1)), the oil and its chemotypes retarded or inhibited the germination and decreased root and aerial growth in monocot and dicot species used in the bioassays. In addition, all substances caused changes in the cell cycle of the meristematic cells of L. sativa, with chromosomal alterations occurring from the 0.015% (w v(-1)) concentration. The essential oil of P. amboinicus, carvacrol, and thymol have potential for use as bioherbicides.

Response of Biomass Development, Essential Oil, and Composition of Plectranthus amboinicus (Lour.) Spreng. to Irrigation Frequency and Harvest Time

“…In India, carvacrol (28.65%), thymol (21.66%), α ‐humulene (9.67%), undecanal (8.29%), γ ‐terpinene (7.76%), p ‐cymene (6.46%), caryophyllene oxide (5.85%), α ‐terpineol (3.28%), and β ‐selinene (2.01%) were the main components of Plectranthus amboinicus . In Brazil, the main constituents of Plectranthus amboinicus essential oil were carvacrol and thymol . In another study in Brazil, p ‐cymene (12.01%), γ ‐terpinene (14.74%), carvacrol (37.70%), and ( Z )‐caryophyllene (14.07%) were reported to be the major constituents .…”

“…[38] In Brazil, the main constituents of Plectranthus amboinicus essential oil were carvacrol and thymol. [39] In another study in Brazil, p-cymene (12.01%), c-terpinene (14.74%), carvacrol (37.70%), and (Z)-caryophyllene (14.07%) were reported to be the major constituents. [40] In Malaysia, the main components of the oil of Plectranthus amboinicus were 3-carene (20.78%), a-terpinene (6.04%), o-cymene (5.06%) c-terpinene (8.94%), camphor (17.96%), and carvacrol (19.29%).…”

Synthesis of Glycerol-Derived 4-Alkyl-Substituted 1,2,3-Triazoles and Evaluation of Their Fungicidal, Phytotoxic, and Antiproliferative Activities

“…After sealing with film paper, the dishes were placed in a biochemical oxygen demand (BOD)-type germination chamber at room temperature (24 ± 2 °C). The percentage of germination (G%) and germination speed index (GSI) were evaluated every 8 h for 48 h. After 48 h, the root length was measured for the indication of root growth (RG), as described by Pinheiro et al 37 To perform the microscopic analysis, ten roots from each Petri dish were collected after 48 h of treatment exposure, fixed in an ethanol-acetic solution (3:1 v/v), and stored at −4 °C. The slides were prepared according to the squash technique and stained with 2% (v/v) acetic orcein.…”

<b>Volatile chemical composition and bioactivities from Colombian <i>Kyllinga pumila</i> Michx (Cyperaceae) essential oil

“…Allelopathy is a process for which products of the secondary metabolism, as terpenes phenolic, of a certain vegetal intervene significantly, generally of antagonistic form, in the development of other species of plants. The volatile terpenes, components of essential oils, show important allelopathic action, as caryophyllene oxide, carvacrol, thymol, 1,8-cineole, among others (Pinheiro et al, 2015;Oliveira, Moreira, & Mendes, 2013;Dias, Gomes, & Dallarmi, 2009).…”