Thin-Layer Chromatography (TLC) in the Screening of Botanicals-Its Versatile Potential and Selected Applications

Microscopic characterization, TLC fingerprinting and optimization of total lipid content from Euphorbia neriifolia (L.) using response surface methodology

Euphorbia neriifolia (EN) is a medicinal plant used to treat a variety of ailments in traditional systems. Despite numerous studies on pharmacological activities, no information was available on the microscopic study of this plant. This is the first study that has been attempted to fill this need by performing the light and field emission scanning electron microscopy (FESEM) of leaf, stem, and latex. The powder microscopy of several organs (leaves, stem, and bark) and exudate (latex) of EN was carried out using safranine, fast green, phloroglucinol, and other standard solutions at different magnifications. The chemical fingerprinting of petroleum ether extract was accomplished by using thin layer chromatography. The optimization of total lipid content from the EN leaf under ultrasound-assisted extraction (UAE) and soxhlet extraction (SE) procedure was determined using response surface methodology (RSM). The studied factors that affect the lipid content were: solvent ratio, extraction temperature, and extraction time. Several notable characteristics observed in the leaf of EN are amphistomatic leaves with anticlinical cell walls, anomocytic stomata, spongy mesophyll cells, elongated palisade cells, angular collenchyma, and U-shaped vascular bundle. The plano-convex midrib is covered by polygonal to oval-shaped cuticles and contains anomocytic stomata. The circular petiole has no trichomes and contains laticifers, crystals, and idioblasts. The circular stem was observed with trichomes, hypodermis, collenchyma, parenchymatous cells, central pith, pentagonal stellar region, cambium, and 2-4 times more xylem that of phloem. All of the powdered plant parts and exudate under study contained trichomes, xylem vessels, wood fibers, cork cells, starch grains, calcium oxalate crystals, idioblasts, lignified cork, tannin content, stone cells, and oil globules. The blackish-green colored petroleum ether extract with semi-solid consistency showed the greatest percent (%) yield of 4% in the latex of EN. The thin layer chromatography (TLC) examination of petroleum ether extract of EN leaf produced a maximum 6 spots with Rf values of 0.16, 0.58, 0.62, 0.73, and 0.96 in the mobile phase of petroleum ether-acetone (8:2). In terms of optimization, the dark green colored UAE extract with semi-sticky consistency showed highest % yield of 4.5% whereas the yellowish green colored SE extract of sticky consistency showed the highest % yield of 4.9%. The findings showed that there were not many differences in the total lipid content between UAE (0.16%) and SE (0.11%). However, the best optimum condition for lipid content extraction analysis was obtained as follows: solvent ratio (PE:HE) 50:50, extraction temperature 50°C, extraction time 45 min for UAE, and solvent ratio (PE:HE) 60:40, extraction temperature 45°C, and extraction time of 24 h for SE. Hence, this study signifies the various noteworthy microscopic features along with the presence of different phytocompounds through TLC and best optimized condition for the extraction of lipids from different parts of EN. As no previous study has been reported, the outcomes obtained from the current study prove to be beneficial in the identification of species, quality control, and detection of any adulteration from the laboratory and commercial samples of EN. RESEARCH HIGHLIGHTS: The percent yield was found to be maximum in latex extract (4%). The leaf pet ether extract was separated into 6 bands with different Rf values. The extracted compounds from Euphorbia neriifolia leaves were categorized into non-polar heat tolerant. The highest total lipid yield (0.1119) was obtained at solvent ratios 60:40 of PE:HE (petroleum ether: petroleum hexane).

Existing status and future advancements of adulteration detection techniques in herbal products

BACKGROUND

Herbal products have been commonly used all over the world for centuries. Its products have gained remarkable acceptance as therapeutic agents for a variety of disorders. However, following recent research disclosing discrepancies between labeling and actual components of herbal products, there is growing concern about the efficacy, quality and safety of the products. The admixture and adulteration of herbal medicinal products pose a risk of serious health compromise and the well-being of the consumers. To prevent adulteration in raw ingredients and final herbal products, it is necessary to use approaches to assess both genomes as well as metabolomics of the products; this offers quality assurance in terms of product identification and purity. The combinations of molecular and analytical methods are inevitable for thorough verification and quality control of herbal medicine.

METHODS AND RESULTS

This review discusses the combination of DNA barcoding, DNA metabarcoding, mass spectroscopy as well as HPLC for the authentication of herbal medicine and determination of the level of adulteration. It also discusses the roles of PCR and real-time PCR techniques in validating and ensuring the quality, purity and identity of the herbal products.

CONCLUSIONS

In conclusion, each technique has its own pros and cons, but the cumulative of both the chemical and molecular methods is proven to be the best strategy for adulteration detection. Moreover, CRISPR diagnosis tools equipped with multiplexing techniques may be implemented for screening adulteration from herbal drugs, this will play a crucial role in herbal product authentication in the future.