Chromatographic Science of Natural Products IV

Dear Colleagues,

Natural products are most often botanicals, e.g., substances obtained from plants, algae, fungi and lichens, including fresh and dried botanic entities and parts or components thereof, isolated through extraction with water or various organic solvents, as well as oils, essential oils and oleoresins obtained through different isolation techniques. Botanicals are typically used in dietary, medicinal or cosmetic products available for purchase in pharmacies, supermarkets, specialist shops and online via the internet. Prior to being included in dietary, cosmetic and especially medicinal preparations, botanicals need authentication, followed by a thorough quality control for safety reasons. General information addressing the general public regarding what quality demands are expected of botanicals is provided in documentation issued by the Department of Health and Human Services in various countries, including pharmacopoeias. In 2011, the World Health Organization (WHO) published guidelines on a wide spectrum of quality control methods for herbal materials, all accompanied by a growing sophistication of analytical tools employed in the respective quality control methods. There is no doubt that an important role in these methodologies is played by gas chromatography (GC), high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC), all equipped with versatile detection systems. There is, however, a cozy but broad enough space left for instrumental thin-layer chromatography in its standard (TLC) and high-performance (HPTLC) modes.

Fingerprinting through chromatographic profiling is a very effective and convenient method for the quality assessment of herbs. By definition, a chromatographic fingerprint is a chromatographic profile or image that represents the chemical characteristics of herbal material. A herbal sample fingerprint can also be defined as a set of characteristic chromatographic or spectroscopic signals, whose comparison leads to a sample recognition. All separation techniques can be applied to construct fingerprints. HPLC is the fingerprinting method of choice due to its specificity, good separability and having the possibility to derive a lot of chemical information. However, HPTLC offers a number of unique features that can outperform the other separation techniques used for fingerprinting. Identification is one of the leading targets of HPTLC, including the possibility of the detection of pharmacologically active compounds, such as antioxidants, inhibitors of selected enzymes and antibiotics. TLC it is the only chromatographic method that allows the presentation of results in the form of an image, also being the only chromatographic technique allowing the parallel separation of samples.

However, one problem associated with classic fingerprinting through the use of various chromatographic methods is the difficulty in indicating with 100% certainty which signals (peaks, bands, etc.) should be present in the obtained chromatographic image or profile (chromatogram) to confirm a sample’s identity, with some methods existing to solve this problem. The first method relies on a comparison of the analyzed sample with a defined botanical reference material (BRM) or a set of standard compounds; the other is a concept of multiple fingerprint construction and multidimensional fingerprinting, having gained much attention as a large amount of chromatographic and/or spectroscopic signals enable more comprehensive data analyses. Other than chemical detection, one method of performing multidimensional fingerprinting is also the use of biological detection. The chemometric approach of chromatograms or profiles, although more difficult, is based only on objective mathematical methods. Fingerprinting is also a method of choice in chemotaxonomy.

This Special Issue of Molecules aims to publish papers providing actual and interesting information regarding the application of chromatographic methods in the area of plant chemistry and the construction of plant fingerprints. Due to the wide interest of the first Molecules Special Issue, “Chromatographic Science of Natural Products I”, “Chromatographic Science of Natural Products II”  and “Chromatographic Science of Natural Products III”, we have decided to continue the consideration of this subject. We look forward to gathering and presenting further advances in this Special Issue entitled “Chromatographic Science of Natural Products IV”.

Dr. Miroslaw Hawryl
Prof. Dr. Monika Waksmundzka-Hajnos
Guest Editors

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