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Front. Microbiol. | doi: 10.3389/fmicb.2019.00474

Aloin alters the intestinal bacterial community structure and short chain fatty acids metabolism

 Sangeeta Khare1*, Pranav Kolluru1, Carl E. Cerniglia1 and  Kuppan Gokulan1*
  • 1National Center for Toxicological Research (FDA), United States

Aloe leaf or purified aloin products possess numerous therapeutic and pharmaceutical properties. It is widely used as ingredients in a variety of food, cosmetic and pharmaceutical products. Animal studies have shown that consumption of aloe or purified aloin cause intestinal goblet cell hyperplasia, and malignancy. Here, we tested antibacterial effects of aloin, against intestinal commensal microbiota. Minimum inhibitory concentration of aloin for several human commensal bacterial species (Gram+ve and Gram-ve) ranged from 1 to 4 mg/ml. Metabolism studies indicated that Enterococcus faecium was capable of degrading aloin into aloe-emodin at a slower-rate compared to Eubacterium spp. As a proof of concept, we incubated 3% rat fecal-slurry (an in vitro model to simulate human colon content) with 0.5, 1, and 2 mg/ml of aloin to test antimicrobial properties. Low aloin concentrations showed minor perturbations to intestinal bacteria, whereas high concentration increased Lactobacillus spp. counts. Aloin also decreased butyrate-production in fecal microbiota in a dose-dependent manner after 24hr exposure. The 16S rRNA sequence-data revealed that aloin decreases the abundance of butyrate-producing bacterial species. Transepithelial resistant result revealed that aloin alters the intestinal barrier-function at higher concentrations (500 µM). In conclusion, aloin exhibits antibacterial property for certain commensal bacteria and decreases butyrate-production.

Keywords: Aloin, commensal bacteria, Antimicrobial activity, Short chain fatty acids (SCFA), Barrier function, epithelial cell

Received: 31 Jul 2018; Accepted: 25 Feb 2019.

Edited by:

Yuheng Luo, Sichuan Agricultural University, China

Reviewed by:

Alex Galanis, Department of Molecular Biology and Genetics, Democritus University of Thrace, Greece
Jing Zhang, Shanghai Jiao Tong University, China  

Copyright: © 2019 Khare, Kolluru, Cerniglia and Gokulan. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Dr. Sangeeta Khare, National Center for Toxicological Research (FDA), Jefferson, 72079, Arkansas, United States, sangeeta.khare@fda.hhs.gov
Dr. Kuppan Gokulan, National Center for Toxicological Research (FDA), Jefferson, 72079, Arkansas, United States, Kuppan.gokulan@fda.hhs.gov