Enzymatic and Antimicrobial Activity of Biologically Active Samples from Aloe arborescens and Aloe barbadensis

SIMPLE SUMMARY: Antimicrobial resistance is one of the major threats to public health, and additional concerns are reduced efficacy and increased toxicity of synthetically derived drugs. Hence, it is all the more important to research new antimicrobials derived from natural sources. Aloe spp. have long been acknowledged in traditional medicine, as their ability of treating skin and digestive problems, wound healing, anti-inflammatory, antimicrobial and other promising properties are known. This study presents the content of various bioactive substances in samples of two Aloe spp., Aloe arborescens and Aloe barbadensis, and their enzymatic, antioxidant and antimicrobial activity. Obtained bioactive compounds with antimicrobial effect have a huge potential to inhibit the growth of microorganisms that are extremely susceptible to gaining resistance and could be used in versatile applications in the cosmetics, food, medical and pharmaceutical industries. ABSTRACT: Recently, the use of Aloe species has become very widespread. These are extensively used as a nutraceutical in a variety of health care products and food supplements. In addition, the occurrence of the quickly adaptable microorganisms, particularly bacteria, which can develop resistance to antibiotics, is a major problem for public health, and therefore, it is necessary to search for new antimicrobials. In our study, the content of total phenols, proanthocyanidins, and proteins in fresh and lyophilized samples of A. arborescens and A. barbadensis and their ethanol extracts was investigated. Furthermore, enzymatic and antioxidant activity of samples were studied. Since antimicrobial activity of fresh samples was determined in our latest research, a more detailed study of antimicrobial effectiveness of A. arborescens and A. barbadensis (lyophilized, extracts) was performed. Ethanol extracts in particular contain higher concentrations of bioactive substances and show the topmost antioxidant activity. The novelty of the study refers to the observation of industrially important enzyme activities such as α-amylase, cellulase, lipase, peroxidase, protease, and transglutaminase in the samples as well as the microbial growth inhibition rates determination (MGIR) at different concentrations of added aloe samples. All samples inhibited the growth of all tested microbial cells. MIC(90) for A. arborescens and A. barbadensis were also determined in case of B. cereus, P. aeruginosa, P. fluorescens, and S. aureus. The results of our study tend to give credence to the popular use of both aloes in medicine and in the cosmetic, food, and pharmaceutical industries.