Counter-current chromatographic method for preparative scale isolation of picrosides from traditional Chinese medicine Picrorhiza scrophulariiflora

Neopicrorhiza scrophulariiflora (Pennell) Hong: A comprehensive review of its traditional uses, phytochemistry, pharmacology and safety

ETHNOPHARMACOLOGICAL RELEVANCE

Neopicrorhiza scrophulariiflora (Pennell) Hong is important medicinal plant that is native to the eastern Himalayas and Hengduan mountains in China. It is also distributed in Nepal, north east India, Bhutan and northern Myanmar. Plant parts are traditionally used against different kinds of diseases and various compounds present in different plant parts are also effective against many diseases. Thus, N. scrophulariiflora has a high potential to maintain human health.

AIM OF THE REVIEW

Although N. scrophulariiflora is very important and widely studied plant species but there is no comprehensive up-to-date review of published and unpublished literature. So, in the present article we have compiled and critically commented on the botanical characteristics, traditional uses, plant growth and cultivation, micropropagation, conservation status, secondary metabolites, pharmacology and toxicity of the plant.

MATERIALS AND METHODS

Extensive literature searches both electronic online databases (Google Scholar, Scopus, Springer Link, Web of Science, ScienceDirect, ResearchGate, PubMed, ChemSpider, USPTO, Google patents and Espacenet) and library visits in Nepal were carried out to collect the literature on information published prior to April 2019.

RESULTS

N. scrophulariiflora was traditionally used for 82 ailments/diseases. There are 124 major phytochemicals extracted from the plant. Several compounds are effective in bioactivity. Pharmacologically, the plant is proved to be anti-atherosclerotic, antidiabetic and anti-inflammatory in-vivo studies, and antimicrobial, antimalarial, antioxidative, hepatoprotective, immunomodulatory and nerve growth factor potentiating from in-vitro studies. Renal improvement activities were confirmed from both in-vivo and in-vitro studies. Toxicological tests and a single clinical trial in human beings have supported the notion that the plant is not poisonous but beneficial for curing wide ranges of diseases.

CONCLUSION

N. scrophulariiflora is valuable medicinal plant that can serve as promising source of non-harmful and potential medicinal herbal remedies for human beings.

Operating mode and parameter selection in liquid-liquid chromatography

The presence of a liquid stationary phase in liquid-liquid chromatography (LLC) allows for high versatility of operation as well as adaptability to different sample types and separation tasks. LLC, also known as countercurrent chromatography (CCC) or centrifugal partition chromatography (CPC), offers the user a variety of operating modes, many of which have no direct equivalent in conventional preparative liquid-solid chromatography. These operating modes have the potential to greatly improve LLC separation performance compared to the standard "classical" isocratic batch injection mode, and they often require minimal to no addition of equipment to the standard set-up. However, reports of the use of alternative LLC operating modes make up only a fraction of the literature. This is likely due, at least in part, to the lack of clear guidelines and methods for operating mode and parameter selection, leaving alternative process options to be avoided and underutilized. This review seeks to remedy this by providing a thorough overview of the available LLC operating modes, identifying the key characteristics, advantages and disadvantages, and areas of application of each. Additionally, the equations and short-cut models aiding in operating mode and parameter selection are presented and critiqued, and their notation is unified for clarity. By rendering LLC and its alternative operating modes more accessible to current and prospective users, it is hoped to help expand the application of this technology and support the achievement of its full potential.

High-performance countercurrent chromatographic isolation of acylated iridoid diglycosides from Verbascum ovalifolium Donn ex Sims and evaluation of their inhibitory potential on IL-8 and TNF-α production

In traditional folk medicine, Verbascum species have been used since ancient times to treat respiratory disorders, hemorrhoids, diarrhea, wounds, eczema and other types of inflammatory skin conditions. Despite the fact that more than 200 bioactive constituents (phenylethanoids, flavonoids, neolignan glycosides, phenolic acids, iridoids, saponins and polysaccharides) have been previously isolated from various Verbascum species, to date preparative high-performance countercurrent chromatography (HPCCC) has never been employed for this purpose. Therefore, in this study, simple HPCCC methods were successfully developed with the aim to primarily isolate acylated iridoid diglycosides from Verbascum ovalifolium Donn ex Sims (oval-leaved mullein). By the use of several biphasic solvent systems containing n-hexane, ethyl acetate, n-butanol/methanol and water, premnacorymboside B (3, 4 mg, 95.4% purity), saccatoside (4, 6 mg, 95.7% purity), premnacorymboside A (7, 6 mg, 98.3%), scorodioside (8, 11 mg, 96.0%) and 6-O-(3'',4''-di-O-trans-cinnamoyl)-α-L-rhamnopyranosylcatalpol (9, 8 mg, 95.3%) were afforded; compounds 7, 8 and 9 have not been previously reported in Verbascum genus. Additionally, two phenolic acids (1, 2), two flavonoids (6, 10) and verbascoside (5) were secondarily isolated. Evaluation of interleukin 8 (IL-8) and tumor necrosis factor α (TNF-α) inhibitory properties of the acylated iridoid diglycosides proved that these compounds down-regulated TNF-α release more efficiently than IL-8 secretion. The activity might be dependent on the degree of esterification, as diacyl derivatives showed more potent effects than monoesters. The HPCCC methods herein developed could serve to large scale isolation of constituents from Verbascum genus for extensive biological investigations.

Countercurrent Separation of Natural Products: An Update

This work assesses the current instrumentation, method development, and applications in countercurrent chromatography (CCC) and centrifugal partition chromatography (CPC), collectively referred to as countercurrent separation (CCS). The article provides a critical review of the CCS literature from 2007 since our last review (J. Nat. Prod. 2008, 71, 1489-1508), with a special emphasis on the applications of CCS in natural products research. The current state of CCS is reviewed in regard to three continuing topics (instrumentation, solvent system development, theory) and three new topics (optimization of parameters, workflow, bioactivity applications). The goals of this review are to deliver the necessary background with references for an up-to-date perspective of CCS, to point out its potential for the natural product scientist, and thereby to induce new applications in natural product chemistry, metabolome, and drug discovery research involving organisms from terrestrial and marine sources.

Separation of nine compounds from Salvia plebeia R.Br. using two-step high-speed counter-current chromatography with different elution modes

Nine compounds were successfully separated from Salvia plebeia R.Br. using two-step high-speed counter-current chromatography with three elution modes. Elution-extrusion counter-current chromatography was applied in the first step, while classical counter-current chromatography and recycling counter-current chromatography were used in the second step. Three solvent systems, n-hexane/ethyl acetate/ethanol/water (4:6.5:3:7, v/v), methyl tert-butyl ether/ethyl acetate/n-butanol/methanol/water (6:4:1:2:8, v/v) and n-hexane/ethyl acetate/methanol/water (5:5.5:5:5, v/v) were screened and optimized for the two-step separation. The separation yielded nine compounds, including caffeic acid (1), 6-hydroxyluteuolin-7-glucoside (2), 5,7,3',4'-tetrahydroxy-6-methoxyflavanone-7-glucoside (3), nepitrin (4), rosmarinic acid (5), homoplantaginin (6), nepetin (7), hispidulin (8), and 5,6,7,4'-tertrahydroxyflavone (9). To the best of our knowledge, 5,7,3',4'-tetrahydroxy-6-methoxyflavanone-7-glucoside and 5,6,7,4'-tertrahydroxyflavone have been separated from Salvia plebeia R.Br. for the first time. The purities and structures of these compounds were identified by high-performance liquid chromatography, electrospray ionization mass spectrometry, (1)H and (13)C NMR spectroscopy. This study demonstrates that high-speed counter-current chromatography is a useful and flexible tool for the separation of components from a complex sample.