Separation of Aloins A and B from Aloe Vera Exudates by High Speed Countercurrent Chromatography

Identification and discrimination of three common Aloe species by high performance liquid chromatography-tandem mass spectrometry coupled with multivariate analysis

Aloe arborescens, Aloe barbadensis and Aloe ferox are the most widely cultivated and used among 500 aloe species due to their potent bioactivity. However, the difference of aloe species is neglected and labeled only one name Aloe in the market without specifying aloe species discrimination in general. Furthermore, differences in bioactivity and side effects from different aloe species have not been well investigated. This study develops an effective method for simultaneous qualitative and quantitative determination of three common aloe species using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and high performance liquid chromatography-diode array detection (HPLC-DAD). The extraction conditions were optimized by response surface methodology (RSM) based on methanol concentration, extraction time and solvent-to-material ratio. A partial least squares-discriminant analysis (PLS-DA) was used to identify the three aloe species. The developed HPLC-MS/MS method coupled with multivariate analysis can be applied to discriminate three aloe species successfully.

Aloe vera as a functional ingredient in foods

The main scientific discoveries on Aloe vera published mainly in the last three decades are presented in this work. After describing Aloe from a botanical point of view, the papers related with the chemical composition of different parts of the leaf of Aloe, particularly those in which the gel is described and are presented in a synthetic manner. The chemical analyses reveal that Aloe gel contains mannose polymers with some glucose and other sugars, among which the most important is Acemannan. Besides these, other components such as glycoproteins, enzymes, amino acids, vitamins, and minerals are described. Different factors also affecting the chemical composition of the gel, such as species and variety, climatic and soil conditions, cultivation methods, processing and preservation, are enumerated and discussed. On the other hand, the main therapeutic applications have been revised and the possible damaging effects of Aloe are also commented upon. A special emphasis is placed on the biologically active compounds or groups of compounds responsible for the therapeutic applications and which are their action mechanisms. The paper concludes that more research is needed to confirm the therapeutic and beneficial effects and to definitively clarify the myth surrounding Aloe vera. A general view on the problem of the commercialization and establishment of the quality and safety of Aloe products in the food industry has been offered here. The main points and European regulations that need to be considered regarding the quality control of prepared Aloe products are presented in this paper.

Separation of epigallocatechin and flavonoids from Hypericum perforatum L. by high-speed counter-current chromatography and preparative high-performance liquid chromatography

High-speed counter-current chromatography (HSCCC) and preparative high-performance liquid chromatography (prep-HPLC) were successively used for the separation of epigallocatechin and flavonoids from Hypericum perforatum L. The two-phase solvent system composed of ethyl acetate-methanol-water (10:1:10, v/v) was used for HSCCC. About 900mg of the crude extract was separated by HSCCC, yielding 7.8mg of quercitrin at a purity of over 97%, 12.6mg of quercetin at a purity of over 93%, and 38.9mg of a mixture of hyperoside, isoquercitrin and miquelianin constituting over 97% of the fraction. A mixture of epigallocatechin and avicularin pooled from three HSCCC runs, a total amount of 54.3mg, was further separated by prep-HPLC yielding 23.4mg of epigallocatechin and 15.3mg of avicularin each at a purity of over 97%.

Natural product isolation

Since the 1990s, interest in natural product research has increased considerably. Following several outstanding developments in the areas of separation methods, spectroscopic techniques, and sensitive bioassays, natural product research has gained new attention for providing novel chemical entities. This updated review deals with sample preparation and purification, recent extraction techniques used for natural product separation, liquid-solid and liquid-liquid isolation techniques, as well as multi-step chromatographic operations. It covers examples of papers published since the NPR review 'Modern separation methods' by Marston and Hostettmann,1 with major emphasis on methods developed and the research undertaken since 2000.