Seasonal variation of the chemical composition and antimicrobial and cytotoxic activities of the essential oils from Inga laurina (Sw.) Willd.

Fabiana Furtado,Francisco De Aquino,Evandro Nascimento,Luís Cunha,Roberto Chang,Claudio Silva,Fabrício Machado,Luís Leandro,Alberto De Oliveira,Sérgio De Morais,Carlos Martins,Carla Martins,Mário Martins

doi:10.3390/molecules19044560

Abstract

The seasonal chemical composition of essential oils from Inga laurina was determined by GC/MS. In the stem bark’s essential oil extracted during the dry season, the presence of terpenoids (30.05%) stood out, and phytol (9.76%) was the major compound identified. For the stem bark oil obtained during the rainy season, in addition to terpenoids (26.63%), a large amount of fatty acids (46.84%) were identified, in particular palmitic acid (25.40%). Regarding the leaves’ essential oil obtained in the dry season, esters (42.35%) were the main components. The main ester present was (Z)-hex-3-enyl benzoate (10.15%) and the major compound of this oil was (Z)-hex-3-en-1-ol (14.23%). Terpenoids (33.84%), long-chain alkanes (27.04%) and fatty acids (21.72%) were the main components of the essential oil from leaves in the rainy season. Phytol (33.21%), nonacosane (21.95%) and palmitic acid (15.20%) were the major compounds identified. The antimicrobial activity against aerobic and anaerobic oral bacteria was evaluated by the microdilution broth method and cytotoxic activity was carried out with Vero cells. The essential oils from the rainy season showed a better inhibition of the bacterial growth with Minimal Inhibitory Concentrations (MIC) values of 25 or 50 µg·mL−1 for aerobic bacteria, and high selectivity against bacteria was observed. The large amount of fatty acids in rainy season oils may be related to the better inhibitory effects observed.

Highlights

Inga laurina (Sw.) Willd. belongs to the Inga genus (Leguminosae) and is popularly known as in Brazil as Angá or Ingá Branco
No significant differences were observed in the yields between essential oils from the bark or leaves with respect to the period of collection, but the yield of the essential oil from leaves was higher than the bark in the dry and rainy season
The essential oils from the bark and leaves of the dry season exhibited minimum inhibitory concentration (MIC) values of or 200 μg·mL−1 and during the rainy season, the essential oils exhibited the lowest inhibitory concentrations with MIC values of 25 or 50 μg·mL−1 (Table 5). These results indicate that the essential oils from bark and leaves extracted in the rainy season showed strong antimicrobial activity against all aerobic oral pathogens evaluated, emphasizing the results for inhibition of growth of S. mutans, principal etiological agent of dental caries, with MIC of 25 μg·mL−1

Summary

Introduction

Inga laurina (Sw.) Willd. belongs to the Inga genus (Leguminosae) and is popularly known as in Brazil as Angá or Ingá Branco. Several species of Inga are used in folk medicine as an anti-inflammatory, an antidiarrheal and a nasal decongestant, and for skin treatment, earache and cleaning teeth [1,2]. Studies of these species have reported the isolation of some metabolites such as depsides [3], metabolites of nitrogen [4], pipecolic acids [5,6], steroidal glycosides [7] and phenolic compounds [1,7,8,9,10,11]. I. laurina extracts have shown antioxidant [13] and antiplasmodial activities [14]

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