Assessing the Chemical Composition and Antimicrobial Activity of Essential Oils from Brazilian Plants—Eremanthus erythropappus (Asteraceae), Plectrantuns barbatus, and P. amboinicus (Lamiaceae)

Abstract

Abstract:The chemical composition and antimicrobial activity of essential oils obtained from three Brazilian plant species-leaves and branches of Eremanthus erythropappus (Asteraceae), leaves of Plectranthus barbatus, and leaves of P. amboinicus (Lamiaceae)-were determined. Analysis by GC/MS and determination of Kovats indexes both indicated δ-elemene (leaves-42.61% and branches-23.41%) as well as (−)-α-bisabolol (leaves-24.80% and stem bark-66.16%) as major constituents of E. erythropappus essential oils. The main components of leaves of P. barbatus were identified as (Z)-caryophyllene (17.98%), germacrene D (17.35%), and viridiflorol (14.13%); whereas those of leaves of P. amboinicus were characterized as p-cymene (12.01%), γ-terpinene OPEN ACCESSMolecules 2015, 20 8441 (14.74%), carvacrol (37.70%), and (Z)-caryophyllene (14.07%). The antimicrobial activity against yeasts and bacteria was assessed in broth microdilution assays to determine the minimum inhibitory concentration (MIC) necessary to inhibit microbial growth. In addition, the crude oil of branches of E. erythropappus was subjected to chromatographic separation procedures to afford purified (−)-α-bisabolol. This compound displayed biological activity against pathogenic yeasts, thus suggesting that the antimicrobial effect observed with crude oils of E. erythropappus leaves and branches may be related to the occurrence of (−)-α-bisabolol as their main component. Our results showed that crude oils of Brazilian plants, specifically E. erythropappus, P. barbatus, and P. amboinicus and its components, could be used as a tool for the developing novel and more efficacious antimicrobial agents.

Antimicrobial Properties of Plant Essential Oils against Human Pathogens and Their Mode of Action: An Updated Review

“…In the study, all Gram-positive bacteria were effectively inhibited with an MIC of 512  μ g/mL. The bacterial strain S. epidermidis was inhibited by the essential oils of Plectranthus barbatus and P. amboinicus with an MIC value of 31  μ g/mL [4, 33]. Likewise, the essential oil of Plectranthus neochilus was shown to inhibit some cariogenic bacteria such as E. faecalis, S. salivarius, Streptococcus sobrinus, Streptococcus sanguinis, S. mitis, S. mutans, and Lactobacillus casei [59].…”

“…Similarly, the inhibitory potential of Aegle marmelos oil against C. albicans, A. niger, and F. oxysporum was demonstrated. The essential oils extracted from Eremanthus erythropappus , P. barbatus, and P. amboinicus were shown to inhibit the growth of C. albicans, Cryptococcus gattii, Cryptococcus neoformans, and S. cerevisiae [33]. Papajani et al [88] have reported the antifungal activity of rosemary essential oil against dermatophytes such as A. cajetani , E. floccosum , M. gypseum , M. canis , T. violaceum , T. mentagrophytes , T. rubrum , and T. tonsurans and phytopathogens such as Botrytis cinerea and Pleomorphomonas oryzae .…”

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

“…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 . In Malaysia, the main components of the oil of Plectranthus amboinicus were 3‐carene (20.78%), α ‐terpinene (6.04%), o ‐cymene (5.06%) γ ‐terpinene (8.94%), camphor (17.96%), and carvacrol (19.29%) .…”

“…[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%). [41] In Morocco, carvacrol (23.0%), camphor (22.2%), d-3-carene (15.0%), c-terpinene (8.4%), and o-cymene (7.7%) were the major constituents of the oil.…”

In vitro evaluation of anticaries, antimycobacterial, antileishmanial and cytotoxic activities of essential oils from Eremanthus erythropappus and of α-bisabolol, their major sesquiterpene

“…and Cryptococcus spp. -, besides antinociceptive, anti-inflammatory, schistosomicidal, antiedematogenic and antiulcerogenic ones (Hillen et al, 2012;Nascimento et al, 2007;Silvério et al, 2013;Santos et al, 2015;Sousa et al, 2008a;Almeida et al, 2012;Keles et al, 2010). However, anticaries, antimycobacterial and antileishmanial activities of EOs from E. erythropappus have not been investigated yet.…”