Chemical composition, antibiotic promotion and in vivo toxicity of Piper nigrum and Syzygium aromaticum essential oil

Abstract

The antimicrobial activity of spices of human daily diet has been widely demonstrated. Yet, their capacity of promoting antibiotic activity has not been explored adequately. In this work, the chemical composition of essential oils of Piper nigrum and Syzygium aromaticum from Chad were determined and their antimicrobial effect in combination with different antibiotics towards Staphylococcus aureus, Salmonella enteritidis and Salmonella typhi were assessed. Moreover, the in vivo toxicity of the essential oils alone and in combination with antibiotics was performed. Results indicate that the essential oil of P. nigrum was mostly composed of limonene (18.59%), beta-pinene (11.51%), linalool (10.17%), alpha-pinene (9.96%), while for S. aromaticum essential oil, only three compounds represented about 89% of the identified compounds. They were respectively beta caryophyllene (43.63%), eugenol (42.67%) and alpha-humulene (3.73%). Regarding the antimicrobial properties, Syzygium aromaticum essential oil (EO) used alone was more active than P. nigrum EO with a minimum inhibitory concentration (MIC) of 625 ppm towards all the strains. In combination with selected antibiotics, S. aromaticum gave better results with less indifference association, the best being with gentamicin. This association of the different EOs with gentamicin proved not to be acutely toxic to rats after 14 days of observation at doses ten times the MIC. These results indicated that spices used in human diets can be used for the production of hybrid drugs containing antibiotic and natural substances.Key words: Piper nigrum, Syzygium aromaticum, antibiotic promotion, Staphylococcus aureus, Salmonella, toxicity. INTRODUCTIONSpices are highly used in Chadian diet and many research works indicate that some of them have biological activities (Beuchat, 1994;Shan et al., 2007). In the continuous search for natural compounds with antimicrobial properties, a more safety approach is to use substances already belonging to human diet. Bacterial infection is one of the most current causes of illness worldwide (Kuete, 2013) and especially in developing countries (Adwan et al., 2008). According to Havelaar et al. (2015), food borne diarrheal disease agents, particularly non-typhoidal Salmonella enterica, cause about 23000 death worldwide, with a high percentage in Africa. In the same report, Salmonella Typhi was recognized as one of the major cause of food borne diseases. Regarding Staphylococcus aureus, Tong et al. (2015) stated that in the industrialized world, the population incidence of S. aureus bacteremia ranges from 10 to 30 per 100,000 person/year.Black pepper (Piper nigrum) has many medicinal properties among which, antibacterial, antifungal, antiinflamatory and antidiarrhoeal are mostly reported (Noumedem et al., 2013). Clove (Syzygium aromaticum) is an aromatic herb that has many useful purposes. Its essential oil has demonstrated several properties as reported by Noumedem et al. (2013). S. aromaticum is widely cultivated in Indonesia, Sri Lanka, Madagascar,...

Evaluation of the Antibacterial Activity of Gentamicin in Combination with Essential Oils Isolated from Different Cultivars and Morphological Parts of Lavender (Lavandula angustifolia Mill.) against Selected Bacterial Strains

“…For this purpose, the biological activity of other major and minor components of lavender essential oils should be tested in analogous conditions to identify the remaining active compounds. Some authors have shown synergistic effects with gentamicin for other essential oils against Gram-positive and Gram-negative bacteria [1,44,[49][50][51]. This was confirmed in our previous study on commercial lavender essential oil [7] and the currently studied oils isolated from different cultivars and morphological parts of lavender, whose combinations with gentamicin have not yet been examined.…”