Formulation and in vitro analysis of essential oil blended (Cymbopogon citratus, Syzgium aromaticum and Melaleuca alternifolia) biocompatible hand sanitizer against common bacterial pathogens

Abstract

ABSTRACT Essential oils (EOs) are predominantly known for their use in aromatherapy, cosmetic, food and pharmaceutical industries. Combination of EOs may result in holistic synergistic effects due to a blended biocompatible mixture. In this study, three EOs were selected out of the seven EOs tested for their efficacy against Gram-positive and Gram-negative bacteria based on the results of disc diffusion. The Minimum Bactericidal Concentration (MBC) of EOs from Cymbopogon citratus (lemongrass), Melaleuca alternifolia (tea tree) and Syzgium aromaticum (clove) were determined against Micrococcus luteus, Bacillus subtilis, Bacillus cereus, Klebsiella pneumoniae and Escherichia coli ATCC 11775. The EOs were analysed using gas chromatography mass spectrometry (GC-MS) to identify the volatile organic compounds. Geranial, neral, neryl acetate and β-caryophyllene were present in highest concentrations among 48 chemicals identified in lemon grass essential oil (LGEO). GC-MS identified 17 chemical compounds in clove EO (CEO) with eugenol, eugenol acetate and β-caryophyllene present in highest concentrations. A total of 52 compounds were identified with terpineol-4, γ-terpinene, α-terpipene and 1,8-cineole (eucalyptol) being the most prevalent compounds in tea tree EO (TTEO). Response surface methodology (RSM) using central composite design (CCD) was used to develop a mathematical model that determined the optimal concentrations of LGEO, TTEO and CEO as 0.10%, 0.11% and 0.10%, respectively. This investigation highlighted the importance of microbiological techniques and statistical optimization tools to study the synergistic effect of selected EOs towards developing a combined EO - based antibacterial treatment technology. Overall, this study showed the potential of developing a biocompatible hand sanitizer which resulted in marked log reduction of bacteria. Further study on the efficacy of the developed EO-mixture against viruses, fungi and nematodes will provide useful scientific knowledge.