Recent Progress in Curcumin: Extraction, Purification, and Bioactivity.

Extraction, purification and applications of curcumin from plant materials-A comprehensive review

In recent years, discovering new drug candidates has become a top priority in research. Natural products have proven to be a promising source for such discoveries as many researchers have successfully isolated bioactive compounds with various activities that show potential as drug candidates. Among these compounds, phenolic compounds have been frequently isolated due to their many biological activities, including their role as antioxidants, making them candidates for treating diseases related to oxidative stress. The isolation method is essential, and researchers have sought to find effective procedures that maximize the purity and yield of bioactive compounds. This review aims to provide information on the isolation or separation methods for phenolic compounds with antioxidant activities using column chromatography, medium-pressure liquid chromatography, high-performance liquid chromatography, counter-current chromatography, hydrophilic interaction chromatography, supercritical fluid chromatography, molecularly imprinted technologies, and high-performance thin layer chromatography. For isolation or purification, the molecularly imprinted technologies represent a more accessible and more efficient procedure because they can be applied directly to the extract to reduce the complicated isolation process. However, it still requires further development and refinement.

An efficient method for bioassay-guided preparative isolation of antioxidants from the n-butanol extract of Astragalus altaicus Bunge was ingeniously developed by combination of silica gel column chromatography and high-speed counter-current chromatography. Under the bioassay-guidance of antioxidant activities, the antioxidants were gradually separated from the crude sample of Astragalus altaicus Bunge by silica gel column chromatography and high-speed counter-current chromatography. Silica gel column chromatography separation was performed with chloroform, chloroform-methanol (100:1~5:1, v/v) and chloroform-methanol-water (5:1:0.1~2:1:0.1, v/v/v). High-speed counter-current chromatography separation was performed with a two-phase solvent system composed of ethyl acetate-n-butanol-water (2:1:6, v/v/v), which was successfully selected by thin layer chromatography analysis, at a flow rate of 1.5 mL/min. As a result, isorhamnetin-3-gentiobioside (20.8 mg), rutin (82.0 mg), and narcissin (12.8 mg) were obtained for the first time from 200 mg of the crude sample, ABS-5 of Astragalus altaicus Bunge. The purities were all at over 95% by high-performance liquid chromatography analysis, and their structures were unambiguously identified by mass spectroscopy, (1) H, and (13) C nuclear magnetic resonance spectroscopy. Antioxidant activities of the three compounds were also assayed by in vitro ABTS [2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) diamonium salt] radical cation scavenging activity. Among them, rutin possessed the highest antioxidant capacity with SC(50) value of 22.15 μg/mL.

The characteristic constituent angoroside C of the famous traditional Chinese medicine Scrophularia ningpoensis hemsley was separated from the crude extract by high speed countercurrent chromatography using reverse phase elution combined with silica gel column chromatography. Meanwhile, harpagoside was also obtained using the normal phase elution method. A two phase solvent system containing n-butanol:acetic acid:ethyl acetate:water (8:1:1:10) was selected according to the partition coefficient of angoroside C. A 311 mg quantity of the crude extract was loaded onto a 250 mL HSCCC column and yielded 49 mg angoroside C at over 89.1% purity, and 14 mg harpagoside at over 96.5% purity. Angoroside C was further purified by silica gel column chromatography and the purity reached 98.5% with high recovery. The chemical structures were determined by ESI/MS n and 1H-NMR. The characteristic ESI/MS n fragmentation pattern of angoroside C and the proposed fragmentation mechanism are proposed.

Separation of polysaccharides from Spirulina platensis by HSCCC with ethanol-ammonium sulfate ATPS and their antioxidant activities

BackgroundRice blast is a devastating disease caused by Magnaporthe grisea, and it is not well controlled globally. As a Traditional Chinese Medicine, Artemisia argyi has been proven to have inhibitory effects on a variety of phytopathogenic fungi. Here, we used bioactivity-guided isolation method and transcriptomics to clarify the antifungal active compounds in A. argyi and their antifungal mechanisms.ResultsIn vitro studies showed that the absolute ethanol extract (AEE) of A. argyi had a strong inhibitory effect on the growth of M. grisea, with a low EC50 value of 1.156 mg/mL, and could cause the destruction of hyphae cell membrane and the leakage of cell contents. To identify the active constituents, we fractionated the AEE using macroporous adsorption resin and silica gel column chromatography. The active fraction (Fr.F-1) was fractionated and had even higher antifungal activity than AEE. The results showed that both AEE and Fr.F-1 could impact primary metabolic pathways and reactive oxygen species homeostasis of M. grisea, decrease the content of reducing sugars and downregulate the expression of genes related to starch and sucrose metabolism. Further fractionation of Fr.F-1 led to the identification of two polymethoxylated flavonoids (eupatilin and 3,5,3ʹ-trihydroxy-7,8,4ʹ-trimethoxyflavone), both of which had antifungal activity and they worked synergistically in Fr.F-1. Finally, we also investigated the effect of AEE, Fr.F-1 and eupatilin on rice blast control. The results showed that AEE, Fr.F-1 and eupatilin application strongly enhanced rice resistance to M. grisea.ConclusionIn brief, these findings indicate that Fr.F-1 subfraction from A. argyi and its main components polymethoxylated flavonoids confer inhibiting activities to M. grisea. This discovery can effectively alleviate the degradation pressure of A. argyi by-products, promote the healthy development of its industry, and provide new a strategy for the development of new botanical fungicides to control rice blast.Graphical

Chemical constituents of ethanol extract of Pulsatillae Radix were investigated. The n-butanol fraction of ethanol extract of Pulsatillae Radix was isolated and purified by macroporous resin and silica gel column chromatography and semi-preparative high performance liquid chromatography. The triterpenoid glycosides were identified by multiple spectral methods. Six compounds were obtained from the n-butanol fraction of ethanol extract of Pulsatillae Radix and identified as 23-aldehyde-cussosaponin C(1), cussosaponin C(2), anemoside B4(3), akebia saponin D(4), pulchinenoside E3(5), and hederacoside C(6). Among them, compound 1 was a new compound.

Following constituents’ enrichment steps with the AB-8 macroporous resin, silica gel, and ODS columns, high-speed counter-current chromatography (HSCCC) and preparative HPLC were successfully used for the isolation and purification of two complex isomeric saponins including a new one from albiziae cortex. The two-phase solvent system used for separation was composed of n -hexane/ n -butanol/water (1:10:5, v/v/v ). A total of 8.2 mg julibroside J 5 a and 11.6 mg julibroside J 5 with purity of higher than 98%, respectively, as determined by HPLC-ELSD were obtained from the constituents enriched fraction (475.4 mg) of albiziae cortex. Their structures were identified by HR-MS, 1 H NMR 13 C NMR, and 2D NMR. This is the first ever report on the separation of complex isomeric saponins from albiziae cortex by HSCCC.

Loganin, sweroside, and morroniside, three main iridoid glycosides from Fructus Corni were successfully separated by macroporous resin column chromatography and countercurrent chromatography (CCC). In the first step, D101 macroporous resin was selected for cleaning-up, water was used to elute the column to remove the undesired constituents and then 50% aqueous ethanol was used to elute the targets. The total content of three iridoid glycosides was 51.1% in this process. In the second step, the obtained crude sample was then isolated by CCC using a two-phase solvent system composed of dichloromethane-methanol-n-butanol-water-acetic acid (5:5:2:4:0.1, v/v/v/v/v). From 100 mg of a crude sample, 12.6 mg of loganin, 5.9 mg of sweroside, and 28.5 mg of morroniside were obtained with purities of 98.6%, 97.3%, and 99.1% and total recoveries of 90.4%, 91.8%, and 89.1%, respectively, after a two-step purification. The HPLC quantitative analysis and response surface methodology were used for optimization of the separation condition and the target compounds were identified by ESI-MS, 1H NMR, and 13C NMR.

Background:Stenoloma chusanum (L.) Ching is a Chinese traditional medicinal fern with high total flavonoid and total phenolic content. Traditionally, phenolic compounds were separated by using column chromatography, which is relatively inefficient. </P><P> Objective: This study aims to use an efficient method to separate natural products from S. chusanum by Medium-Pressure Liquid Chromatography (MPLC) and High-Speed Counter-Current Chromatography (HSCCC).Methods:In the present research, firstly, a sample (2.5 g) from the dichloromethane extract of S. chusanum was separated by MPLC. Next, fraction P5 was purified by HSCCC with a two-phase solvent system composed of hexane-ethyl acetate-methanol-water (HEMWat) at a volume ratio of 2:4:1:4 (v/v/v/v). </P><P> Result: Four phenolic acids were obtained and their structures were identified by means of NMR and ESI-mass analysis. They were identified as: 1) protocatechuic acid (34 mg, purity 90.1%), 2) syringic acid (66 mg, purity 99.0%), 3) p-hydroxybenzoic acid (5 mg, purity 91.2%) and 4) vanillic acid (6 mg, purity 99.3%).Conclusion:The combination of MPLC and HSCCC is a high-efficiency separation method for natural products. This is the first report with regard to the separation of four phenolic acids in one step by MPLC and HSCCC from S. chusanum (L.) Ching.

Purification of high-throughput organic synthesis libraries by counter-current chromatography

Chiral analysis in food science

Antioxidant activity and active compounds of rice koji fermented with Aspergillus candidus

As an alternative to Dendrobium candidum, protocorm-like bodies (PLBs) of Dendrobium candidum are of great value due to their high yield and low cost. In this work, three glycoside compounds, β-D-glucopyranose 1-[(E)-3-(4-hydroxyphenyl)-2-propenoat] (I), β-D-glucopyranose 1-[(E)-3-(3, 4-dihydroxyphenyl)-2-propenoat] (II), and 1-O-sinapoyl glucopyranoside (III), were extracted and isolated by ultrahigh pressure extraction (UPE) coupled with high-speed counter-current chromatography (HSCCC) from PLBs of D. officinale. First, the target compounds were optimized and prepared with 50% ethanol solution at a 1:30 (g/mL) solid/liquid ratio in 2 min under 300 MPa by UPE. Then, the crude extract was chromatographed with a silica gel column, and primary separation products were obtained. In addition, the products (150 mg) were separated by HSCCC under the solvent system of MTBE-n-butyl alcohol-acetonitrile-water (5:1:2:6, v/v/v/v), yielding 31.43 mg of compound I, 10.21 mg of compound II, and 24.75 mg of compound III. Their structures were further identified by ESI-MS, 1H NMR, and 13C NMR. The antioxidant results showed that the three compounds expressed moderate effects on the DPPH· scavenging effect. Compound II had the best antioxidant capacity and its IC50 value was 0.0497 mg/mL.

Ion-pair reagents and reversed micelles in supercritical carbon dioxide (SF-CO2) were tested as polar mobile phases for supercritical fluid chromatography (SFC). Dioctylsulphosuccinate sodium salt (DSS) was used as the counter-ion in ion-pair supercritical fluid chromatography (IP-SFC) with a packed silica-gel column. DSS/pentane reversed micelles were used in reversed micelle supercritical fluid chromatography (RM-SFC) with a packed fluoroalkyl silica-gel column. IP-SFC and RM-SFC using DSS was demonstrated for analytical separation of ephedrine alkaloids.