Assessment of major centelloside ratios in Centella asiatica accessions grown under identical ecological conditions, bioconversion clues and identification of elite lines

Centellosides viz., asiatic acid, madecassic acid, asiaticoside, madecassoside, are the major bioactive molecules in Centella asiatica. In this study madecassic acid:asiatic acid, madecassoside:asiaticoside (C6-hydroxylation versus non-hydroxylation) and asiaticoside:asiatic acid, madecassoside:madecassic acid (C28-glycoside versus aglycone) ratios in 50 C. asiatica accessions originally collected from their natural habitats in south India and grown under identical ecological conditions for six generations were determined using validated HPTLC-densitometry protocols. Asiatic acid, madecassic acid, asiaticoside and madecassoside contents ranged from 0.00-0.29% (average 0.03 ± 0.06%; 28 accessions recorded asiatic acid content as zero), 0.02-0.72% (0.12 ± 0.13%), 0.04-2.41% (0.44 ± 0.52%) and 0.15-5.27% (1.59 ± 1.26%), respectively. Distinctly, C6-hydroxylated (madecassic acid:asiatic acid 4.00, madecassoside:asiaticoside 3.61) and C28-glycosylated (asiaticoside:asiatic acid 14.67, madecassoside: madecassic acid 13.25) centellosides dominated over the respective non-derivatized entities. Our results infer that both C6-hydroxylation by CYP450-dependent monooxygenases and C28-glycosylation by UDP-Glc glucosyltransferases are dominant bioconversion steps in C. asiatica. Besides, this study discovered six elite lines of C. asiatica, with their (asiaticoside + madecassoside) contents above the industrial benchmark (≥ 4%) from south India. Two elite clones with asiaticoside contents ≥ 2% were also identified. Standardization of the agrotechniques of these elite lines could lead to their industrial applications. Further, this study emphasizes the need for standardizing all four centellosides as biomarkers in C. asiatica raw drugs, pharmaceutical and cosmetic products.

Eutectic Thin-Layer Chromatography as a New Possibility for Quantification of Plant Extracts-A Case Study

Deep eutectic solvents (DES), compared to classic ones, have interesting properties, such as the ability to solubilize compounds differing in polarity or increased dissolution of selected chemical compounds. They also offer specific interactions between the mobile and stationary phases. Those features make them promising solvents in chromatographic techniques, including the use in the separation of complicated samples. The first quantitative analysis with eutectic thin-layer chromatography (TLC) is presented in the paper. As a case study, five alkaloids from Chelidonium maius were selected as target compounds. A wide range of terpene-based DESs was investigated to develop the chromatographic system, both pure and after dilution. Moreover, a novel approach was employed to adjust polarity, involving mixing DESs differing in chromatographic properties. This procedure has proved to be effective. The best results were obtained with a 2:1 (wt/wt) mixture of DESs: camphor + phenol and menthol + limonene, with a 20% addition of methanol. The chromatographic system was validated and checked on the real sample, which made it the first applicable and operational quantitative eutectic TLC system.