Profiling the Philippine Blue: Liquid chromatography/mass spectrometry‐based metabolomics study on Philippine Indigofera

Abstract

Rationale High‐throughput liquid chromatography/mass spectrometry (LC/MS) analysis presents an interesting platform for natural dyes research. A particular example is the assessment of the dynamic changes in fermentation mixtures of Philippine Indigofera, and in the investigation of commercially available indigo prepared using traditional and optimized methods. Methods Leaves from Indigofera tinctoria and Indigofera suffruticosa were subjected to methanolic extraction and aqueous fermentation for 48 h. Indigo powders prepared following 2‐day and 15‐day fermentation were also subjected to profiling using ultra‐high‐performance liquid chromatography/quadrupole time‐of‐flight mass spectrometry (UHPLC/QTOF‐MS). MS2 spectra were annotated through a library search in the community‐curated Global Natural Products Social Molecular Networking (GNPS). Spectra with no library hits in GNPS were annotated by analysis of their fragmentation pathways. Results UHPLC/MS‐based detection and fragmentation analysis led to characterization of leucoindigo and the unreported tryptanthrin intermediate, 5a‐hydroxy‐5,5a‐dihydroindolo[2,1‐b]quinazoline‐6,12‐dione, in the fermentation extract of I. tinctoria leaves. Indigo‐associated metabolites were absent in an Indigofera specimen in Laguna Province, which explained why it did not produce blue dye. Locally produced indigo was abundant in indigotin and indirubin, differentiated based on product ions with the corresponding predicted fragmentation pattern. The relative intensity of indigotin, however, decreased with the traditional process of extended fermentation to produce indigo. Conclusions The study is the first to demonstrate simultaneous MS‐based analysis of reaction intermediates, indigotin dye, side products, and catabolites on actively transforming fermentation extracts of I. tinctoria. New results include annotated mass spectra for leucoindigo, and for the unreported 5a‐hydroxy‐5,5a‐dihydroindolo[2,1‐b]quinazoline‐6,12‐dione, which is probably an intermediate in tryptranthrin synthesis. The proposed fragmentation schemes could guide the annotation of analogous compounds in complex mixtures.

Combining the In Silico and In Vitro Assays to Identify Strobilanthes cusia Kuntze Bioactives against Penicillin-Resistant Streptococcus pneumoniae

“…Overall, 74 compounds are defined in Table S2 . Five main peaks at 11.23 min, 25.29 min, 33.10 min, 33.33 min, and 41.58 min were analyzed by MS/MS fragments according to previous studies ( Figure 3 , Table S2 ), and defined as the caffeoyl quinic acid (CQA) [ 20 , 21 ], Hispiduloside [ 22 ], Tryptanthrin [ 23 , 24 ], Hispidulin [ 22 ] and Indirubin [ 25 , 26 ], respectively. Among them, the Tryptanthrin (peak at 33.1 min) showed the highest effective inhibition on the PRSP F3983 with MIC 25 µg/mL ( Table 3 ).…”

Sustainable Hues: Exploring the Molecular Palette of Biowaste Dyes through LC-MS Metabolomics

“…Instrumental analysis was performed based on a method that has been optimized for natural dyes [18]. Profiling of extracts were carried out using Waters Acquity ® Ultrahigh Performance Liquid Chromatography (UPLC ® ) system in tandem with a Xevo G2-XS quadrupole time-of-flight mass spectrometer.…”

“…Additionally, present in some dye baths are other small molecules such as hydrophobic lipids that could affect the interaction of the chromophores on fibers [17]. Untargeted small molecule analysis, therefore, is crucial to understand the complex color yielded by crude natural dyes [18]. LC-MS-based metabolomics presents a sophisticated platform for the sensitive detection, characterization, and comparison of small molecules present on natural dye samples [18].…”

“…Untargeted small molecule analysis, therefore, is crucial to understand the complex color yielded by crude natural dyes [18]. LC-MS-based metabolomics presents a sophisticated platform for the sensitive detection, characterization, and comparison of small molecules present on natural dye samples [18]. Through stateof-the-art instrumentation in the form of ultra-high performance liquid chromatography in tandem with high-resolution mass spectrometry (UHPLC-HRMS), the mass spectra of small molecules can be acquired without extensive purification [19].…”

Discovery of metabolic markers for the discrimination of Helwingia species based on bioactivity evaluation, plant metabolomics, and network pharmacology

“…At present, the molecular network is widely used in the field of natural products as a research tool. [21][22][23][24][25] In this paper, GNPS molecular networking and CD software are utilized together for the rapid identification of compounds in three different HJs.…”