TLC-Bioautography as a fast and cheap screening method for the detection of α-chymotrypsin inhibitors in crude plant extracts

Chymotrypsin and Trypsin Inhibitory Activity of Some Medicinal Plants Collected from Rize (Türkiye)

In this research, the evaluation of in vitro chymotrypsin and trypsin inhibitory activities of ten plant species collected from Rize were aimed, and fractions that showed strong activity were analyzed through HPLC. Daphne pontica L. and Mentha longifolia (L.) L. were found to have the highest chymotrypsin inhibitory activities (87.75 and 84.24 % inhibition). Similarly, the highest trypsin inhibitory activity was observed in D. pontica (%99.93 inhibition), followed by Sambucus ebulus L. flowers (87.47 % inhibition). Extracts showing strong enzyme inhibition were fractioned and subjected to activity tests. The highest chymotrypsin inhibitory activity was observed in the n-hexane fraction of D. pontica (%80.70 inhibition), while the highest trypsin inhibitory activity was found in the n-butanol fraction of S. ebulus (%86.81 inhibition). HPLC studies determined that the 80 % ethanol extract of D. pontica and its dichloromethane and ethyl acetate fractions contained umbelliferone. It was found that chlorogenic acid was present in the 80 % ethanol extracts of S. ebulus flowers. M. longifolia was found to contain chlorogenic acid, caffeic acid, luteolin-7-glucoside, and rosmarinic acid. M. longifolia has been identified as the plant exhibiting the highest antioxidant activity in ABTS and CUPRAC tests, consistent with its high phenolic and flavonoid content.

Effect-directed analysis in food by thin-layer chromatography assays

Thin-layer chromatography (TLC) is widely used for food analysis and quality control. As an open chromatographic system, TLC is compatible with microbial-, biochemical-, and chemical-based derivatization methods. This compatibility makes it possible to run in situ bioassays directly on the plate to obtain activity-profile chromatograms, i.e., the effect-directed analysis of the sample. Many of the properties that can be currently measured using this assay format are related to either desired or undesired features for food related products. The TLC assays can detect compounds related to the stability of foods (antioxidant, antimicrobial, antibrowning, etc.), contaminants (antibiotics, pesticides, estrogenic compounds, etc.), and compounds that affect the absorption, metabolism or excretion of nutrients and metabolites or could improve the consumers health (enzyme inhibitors). In this article, different food related TLC-assays are reviewed. The different detection systems used, the way in which they are applied as well as selected examples are discussed.

Optimization of Ultrasonicated Kaempferol Extraction from Ocimum basilicum Using a Box-Behnken Design and Its Densitometric Validation

Kaempferol (KA) is a natural flavonol that can be found in plants and plant-derived foods with a plethora of different pharmacological properties. In the current study, we developed an efficient extraction method for the isolation of KA from ultrasonicated basil leaves (Ocimum basilicum). We successfully employed a Box-Behnken design (BBD) in order to investigate the effect of different extraction variables including methanol concentration (40-80%), extraction temperature (40-60 °C), and extraction time (5-15 min). The quantification of KA yield was carried out by employing a validated densitometric high performance thin layer chromatography in connection with ultraviolet detection (HPTLC-VIS). The obtained data showed that the quadratic polynomial model (R² = 0.98) was the most appropriate. The optimized ultrasonic extraction yielded 94.7 ng/spot of KA when using methanol (79.99%) at 60 °C for 5 min. When using toluene-ethyl acetate-formic acid (70:30:1 v/v/v) as a solvent, KA was detected in basil leaves at an Retention factor (Rf) value of 0.26 at 330 nm. Notably, the analytical method was successfully validated with a linear regression of R² = 0.99, which reflected a good linear relationship. The developed HPTLC-VIS method in this study was precise, accurate, and robust due to the lower obtained results from both the percent relative standard deviation (%RSD) and SEM of the O. basilicum. The antioxidant activity of KA (half maximal inhibitory concentration (IC₅₀) = 0.68 μg/mL) was higher than that of the reference ascorbic acid (IC₅₀ = 0.79 μg/mL) and butylated hydroxytoluene (BHT) (IC₅₀ = 0.88 μg/mL). The development of economical and efficient techniques is very important for the extraction and quantification of important pharmaceutical compounds such as KA.

The TLC-Bioautography as a Tool for Rapid Enzyme Inhibitors detection - A Review

Microorganisms and plants can be important sources of many compounds with potential pharmaceutical applications. Extraction of these matrices is one of the ways of identifying the presence of inhibitory active substances against enzymes whose high activity leads to serious human diseases including cancer, Parkinson's or Crohn's diseases. The isolation and purification of inhibitors are time-consuming and expensive steps in the analysis of the crude extract and therefore, it is necessary to find a fast, efficient, and inexpensive method for screening extracts of interest. TLC-Bioautography combines the separation of the extract on a thin layer with its subsequent biological analysis. TLC-Bioautography methods have been developed for several classes of enzymes including oxidoreductases, hydrolases and isomerases, and there is a potential for developing functional methods for other classes of enzymes. This review summarizes known TLC-Bioautography methods and their applications for determining the presence of enzyme inhibitors in extracts and compares the effectiveness of different methodological approaches. It also indicates the current state and perspective of the development of TLC-Bioautography and its possible future applications.

Perspective on chymotrypsin detection

Chymotrypsin is one of the most extensively known proteases participating in the pathogenesis of various diseases, which can be used in drug discovery and clinical diagnosis.