Chemical Composition and Antimicrobial Activity of Essential Oils ofOcimum basilicum,Ocimum canumandOcimum gratissimumin Function of Harvesting Time

Abstract

Abstract:The chemical composition of essential oils obtained by hydrodistillation from aerial parts of Ocimum basilicum, Ocimum canum and Ocimum gratissimum from Benin as affected by harvesting time, were analyzed by GC-FID (Gas chromatography-Flame ionization detector) and GC-MS (Gas chromatographyMass spectrometry). Based on the composition analysis, major components were as follows: estragol (43.0 -44.7 %) and linalool (24.6 -29.8 %) in O. basilicum oils; carvacrol (12.0 -30.8 %) and p-cymene (19.5 -26.2 %) in O. canum oils; thymol (28.3-37.7 %) and γ-terpinene (12.5-19.3 %) in O. gratissimum oils. Disc diffusion and broth microdilution assays were used to evaluate the antibacterial activity of essential oils and their main components against two foodborne bacteria, Listeria monocytogenes and Salmonella enterica serotype Typhimurium. The tested oils and their components exhibited notable antimicrobial activities against L. monocytogenes and S. Typhimurium. The O. canum and O. gratissimum oils collected at 7h and 19h showed significant higher activities against L. monocytogenes and S. Typhimurium (MICs and MBCs 0.34 -2.5 μL/ mL) (p < 0.05), whereas O. basilicum showed lower activity (MICs and MBCs 2.0 -8.0 μL/mL) at any daytime of harvest, the weakest being at 19h (MIC and MBC 12.0 -32.0 μL/mL). The daytime of harvest can influence the composition of oils and their activities on bacteria.

Antimicrobial activity of essential oil and growth of Ocimum basilicum (L.) inoculated with mycorrhiza and humic substances applied to soil

“…Among Gram-negative bacteria, Salmonella enterica, Shigella flexneri, Klebsiella pneumoniae, and Xanthomonas axonopolis were responsive to the EO antimicrobial effect, with inhibition occurring at 2.5-10.0 mg/mL MIC. Mith et al (2016) found a low antimicrobial activity of the basil EO for Salmonella enterica and L. monocytogenes. These authors also found linalool (24.6-29.8%) and estragole (43-47.7%) as major compounds of the basil EO.…”

“…Some researchers have reported that antimicrobial activities of the basil EO are predominantly associated with its major constituents: estragole and linalool (Elansary et al, 2016;Mith et al, 2016;Avetisyan et al, 2017;Hanif et al, 2017).…”

Antibacterial and Antifungal Activities of Ocimum Gratissimum L.

“…The studies related to the efficacy of essential oil of Ocimum gratissimum against gram-negative [25][26][27][28], gram-positive bacteria [25][26]35], fungi [30,36], and its regular consumption as spice without affecting the activities of conventional antibiotics [37], makes it a strong antimicrobial herbal product throughout the tropics.…”

“…Plant oil is considered the Mother Nature's chemical factory [20] shows a unique composition of alcohols, aldehydes, ketones, ethers, esters, lactones, oxides, peroxides [21], tannins [22] and flavonoids [23]. The plant obtained from various regions in Africa mainly contain eugenol, thymol, methyl eugenol, camphor, (Cis)-ocimene, (trans)-ocimene, β-pinene, gramicidin D, (trans)-caryophyllene, Γ-terpinene and p-cymene [24][25][26]. Brazilian and Asian races contain phenylephrine (eugenol) as the chief constituent [27][28][29] along with sesquiterpene (caryophyllene), monoterpenes (β-ocimene) [25], bornyl acetate and some non terpene components [30].…”

“…The plant extract is a good anti-diarrheal agent showing a remarkable inhibition of E. coli [43][44], Shigella sp. and Salmonella sp [43] Salmonella enteritidis [26], Shigella flexineri [25,28] Salmonella typhi, Shigella dysenteriae, Aeromonas sobria, and Plesiomonas shigelloides, with strongest action against S. dysenteriae [44]. [25,52] along with S. aureus and E. coli [25,[52][53][54], S. typhimurium [54], Salmonella enteritidis [2] and also restrict extracellular protease enzyme kinetics of E. Coli [55].…”