Figure 1 - uploaded by Vasudha Agnihotri
Content may be subject to copyright.
Source publication
![Figure 1 Structures of ginkgolides (A) and bilobalide (B) of G. biloba [4].](profile/Vasudha-Agnihotri/publication/257118581/figure/fig1/AS:669295403089924@1536583867197/Structures-of-ginkgolides-A-and-bilobalide-B-of-G-biloba-4_Q320.jpg)
Context in source publication
Context 1
... and duration of heating play an important role in detection of ginkgolides and bilobalide. Figure 1A depicts the known chemical structure of ginkgolides (A, B, and C) with varying number of hydroxyl groups. In the TLC plate develop- ment, the plates are sprayed with acetic anhydride before heat- ing, which makes the hydroxyl group partially acetylated. ...
Citations
Detection of target compounds, particularly trace amounts of micropollutants or biomarkers in complex samples, is a key step of chromatographic analysis. In principle, any qualitative and/or quantitative analysis demands a suitable signal to noise ratio allowing chromatographic detection with an appropriate contrast. In planar chromatography and related techniques (e.g., microfluidic-paper-based devices) this can be achieved by online or pre/postseparation reactions of analytes with a variety of visualization reagents. This process is commonly described as staining and/or derivatization and allows effective detection of components of interest, which in their native form are transparent to a given detector at specific data acquisition conditions. Typically, the analytical signal results from physicochemical interactions, chemical reactions, or UV/thermal decomposition. Visualized zones on a thin-layer chromatography (TLC) plate can be acquired by detectors usually operated within the UV-Visible-IR range in the absorbance or fluorescence mode recorded in reflectance or transmission by digital cameras, scanners, or video densitometers. This chapter provides a practical overview of commonly applied derivatization protocols, including application techniques and reagents types, which are frequently used for fast, sensitive, and nonexpensive detection of a wide range of target compounds on thin-layer chromatography plates, bars, or strips coated with different stationary phases. Derivatization techniques in terms of both quantitative and qualitative analysis, detection of specific physicochemical or biological properties of target compounds, as well as selected problems associated with signal optimization are highlighted. Moreover, visualization protocols for detection of target components on TLC plates included in the General Monographs of the European Pharmacopoeia are summarized as an example of the extensive use of staining and derivatization reagents for qualitative and quantitative analysis.
Indiscriminate use of antibiotics that often results in the development of “side effects” and “drug resistance” in the disease-causing agents indicates the need to search for alternate approaches for combating the infectious diseases. In this perception, discovery of new antimicrobials of plant origin, as reliable source of antibiotics, has received attention of the scientific community. Medicinal plants have been recognized as a major source of bioactive compounds. The importance of medicinal plants as a source of potential antimicrobials in a strategic manner and the associated challenges with a note on future prospects the main focus of this chapter. The initiatives taken worldwide on the subject along with the issues such as biodiversity, conservation, and the prioritization of the medicinal plants and importance of the institutional setup and regulatory policies are also highlighted.
The most important advances in the planar chromatography published between November 1, 2009 and November 1, 2011 are reviewed in this paper. Included are an introduction to the current status of the field; history, student experiments, books, and reviews; theory and fundamental studies; apparatus and techniques for sample preparation and TLC separations (sample application and plate development with the mobile phase); detection and identification of separated zones (chemical and biological detection, TLC/MS, and TLC coupled with other methods); techniques and instruments for quantitative analysis; preparative layer chromatography; and thin layer radiochromatography. Selected applications are given in the various sections of the review, especially for modern HPTLC-densitometry.
