title: Bioprofiling of unknown antibiotics in herbal extracts: Development of a streamlined direct bioautography using Bacillus subtilis linked to mass spectrometry.
abstract: Working in the field of profiling and identification of bioactive compounds in herbal extracts is faced with the challenge that common chromatographic methods do not directly link to bioactive compounds. Direct bioautography, the combination of TLC/HPTLC with bioassays, linked to structure elucidating techniques is demonstrated to overcome this challenge. The combination of TLC and Bacillus subtilis bioassay was already demonstrated to detect the antibiotics in samples. However, previous studies in this field were faced with some challenges, like being time-consuming, leading not to a homogenous plate background or being restricted to a non-acidic mobile phase. In this study, these aspects were investigated and a streamlined HPTLC-B. subtilis bioassay was developed that generated a homogenous plate background, which was crucial to yield a good baseline for biodensitometry. Two commonly used broths for B. subtilis and a self-designed medium were compared with regard to their capability of detection and baseline noise. The workflow developed allowed the use of acidic mobile phases for the first time. To prove this, 20 herbal extracts were screened for antimicrobial substances developed in parallel with an acidic mobile phase. The main antimicrobial substance in Salvia officinalis tincture detected was further characterized by microchemical reactions, Aliivibrio fischeri, β-glucosidase and acetylcholinesterase (bio)assays as well as mass spectrometry. Scientists looking for new herbal-based medicine may benefit from this time-saving and streamlined bioactivity profiling.
authors.affiliation: Interdisciplinary Research Center (IFZ) and Institute of Nutritional Science, Chair of Food Science, Justus Liebig University Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany. Electronic address: Maryam.Jamshidi-Aidji@ernaehrung.uni-giessen.de.
authors.forename: Maryam
authors.initials: M
authors.lastname: Jamshidi-Aidji
authors.affiliation: Interdisciplinary Research Center (IFZ) and Institute of Nutritional Science, Chair of Food Science, Justus Liebig University Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany. Electronic address: Gertrud.Morlock@ernaehrung.uni-giessen.de.
authors.forename: Gertrud E
authors.initials: GE
authors.lastname: Morlock
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D048908:Aliivibrio fischeri / Q000187:drug effects*; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D001412:Bacillus subtilis / Q000187:drug effects*; D001681:Biological Assay / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002855:Chromatography, Thin Layer / Q000379:methods*; D004353:Drug Evaluation, Preclinical; D013058:Mass Spectrometry / Q000379:methods*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D001617:beta-Glucosidase / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts; D000110:Acetylcholinesterase; D001617:beta-Glucosidase
keywords: Antimicrobial compound; Bioautogram; Bioautography; Biodensitogram; HPTLC-Bacillus subtilis bioassay; Herbal extract