Current Bioactive Compounds - Volume 7, Issue 2, 2011

This issue is dedicated to scientists belonging to the fields of phytoanalysis, -chemistry and -pharmacy, respectively. Today there is an increasing need for the qualitative and quantitative analysis of medicinal plants since each of them is composed of a great number of beneficial compounds with different pharmacological activity. In case of medicinal plants, the identification, discrimination and classification are especially difficult due to their complex sources. Many plants have multiple related species being similar in morphology, cytology and even genome. Moreover, some medicinal products are often mixed or adulterated with other less effective parts of the same plant having no medicinal benefit at all. Many medicinal plants are especially prepared before use according to some historical guidelines, e.g. those from traditional Chinese medicine (TCM). Different preparation methods including drying, cutting, stir-frying, cooking, etc. may directly affect the quality of medicinal plants and extracts derived there from. In the past, especially traditional medicines were identified and discriminated by experienced personal, which is limited to self-experience and ability of determination. During the last years, some computer aided research was carried out to conduct numerous taxonomy researches on the origin of plants which may provide evidence for the classification and identification of the crude medicinal material. Although these methods were found to be helpful, no real break-through was achieved due to the highly complex calculation methods needed to be implemented. Therefore, in the last few years, research was focused on alternative techniques comprising computer supported calculations, mainly multivariate methods, and infrared spectroscopic techniques. The quantitative determination of a single compound in a plant often leads to a loss of information about the whole plant metabolite because extraction, purification and separation procedures are established to analyze a single compound of interest. So in many cases other pharmacological active ingredients are not accounted playing an important role for the activity. In recent years, the main research was focused on fingerprint techniques, such as gas chromatography (GC), liquid chromatography (LC), thin layer chromatography (TLC), capillary electrophoresis (CE), capillary electrochromatography (CEC), nuclear magnetic resonance (NMR), etc., which are helpful to give an overall understanding of the pharmacological active ingredients. Similar to the demand for a novel strategy to fulfill qualitative requirements, the simultaneous determination of multiple compounds needs for alternative analytical techniques. Therefore, infrared spectroscopy including mapping and imaging of distributed pharmacological active ingredients are known as a flexible, robust, non-invasive, highly reproducible and highthroughput analytical tool for the qualitative and quantitative characterization of medicinal plants and their constituents.

Volatile chemical compounds responsible for the aroma of plant materials are derived from a number of different biochemical and chemical pathways. These chemical compounds are formed during plant metabolism, processing (i.e. fermentation) and post-harvest storage. Not surprisingly, there are a large number of chemical classes of compounds found in plant materials which are present at varying concentrations (ng L-1 to mg L-1), exhibit different degrees of intensity, and have a broad range of boiling points. For many years, classical separation and chromatographic and spectrometric techniques such as gas chromatography (GC) and liquid chromatography (LC) have been used for the isolation and elucidation of volatile compounds from different plant matrices. Spectroscopic techniques in the infrared (IR) wavelength region of the electromagnetic spectrum have been used in the food industry to monitor and evaluate the composition of foods. In the last 10 years IR spectroscopy became one of the most attractive and used methods for plant analysis. This short review discussed the use, with advantages and limitations, of IR spectroscopy technologies to study volatile compounds and secondary metabolites in plant materials.

Traditional Chinese Medicine (TCM) is becoming more and more popular all over the world. Novel analytical tools for quality control are highly demanded enabling analysis starting at breeding and ending at biological fluids including urine or serum. Compared to analytical separation methods (chromatography, electrophoresis) near-infrared spectroscopy (NIRS) allows analyzing matter of interest non-invasively, fast and physical/chemical parameters simultaneously. It can be used for the quantitative control of certain (active) ingredients. In many cases identification can only be achieved by pattern recognition. Therefore, NIRS combined with cluster analysis offers huge potential to identify e.g. species, geographic origin, special medicinal formula etc. In the present contribution the fundamentals, possibilities of NIR applied in quality control of TCM are pointed out and its ad- and disadvantages are discussed in detail by several practical examples.

During the whole human history and particularly in the recent years, various plants of medicinal importance are being utilized for curing various diseases and ailments. A huge world population knowingly or unknowingly is using herbal medicines. The investigations have already shown that there is a strong correlation between current therapeutics and traditional plants. However, there are renewed attempts in phytochemistry research to investigate the medicinally important compounds. Various plants have the ability to produce substances which can be beneficial in health issues. However, one should be aware of the adverse effects. Therefore, more and more authentic analytical techniques are now-adays available which provide the chemists an opportunity with greater flexibility, in the isolation and analysis of extracted bioactive compounds. Particularly, the IR spectroscopy is an extensively used tool for investigating the different structural aspects of these medicinal compounds. The results and achievements made through this tool are comprehensive, easy to interpret and relate with the other structural techniques. The said standing of IR spectroscopy accomplishments are very well reviewed here, particularly the achievements attained by infrared spectroscopy alone or in hyphenation with liquid chromatographic approaches for the analysis of such compounds. Such couplings and strategies are vital to design to deal with the complex sources. IR scanning yields a simultaneous picture of the compounds present in an extract. The efficient and accurate extractions and identifications of pharmacological compounds help then in establishing the disease specific drugs.

The aim of this paper was to review the ability of NIR spectroscopy to determine fermentative volatile compounds, oak volatile compounds, ethylphenols, haloanisoles, and halophenols in aged red wines, which are the highest quality and reputation in the market. Six hundred wines from four different Spanish geographic zones aged during different storage time (at least 6, called as “crianza”, 12, called as “reserva”, and 18 months, called as “gran reserva”) in different oak barrel types were evaluated. These four zones commercialized around 72% of all red wines in Spain and were representative of the entire Spanish territory. Spectra of samples obtained by NIR were co-related with SBSE-GC-MS volatile compounds data using partial least squares regression. For fermentative compounds, results showed that the calibration statistics were excellent (R2>0.98). Validation statistics showed the quality of the model, especially when was done separately for each of the four zones and for wines elaborated with two different grape varieties; in general, the residual predictive deviation (RPD) was higher than 1.5. For oak compounds and ethylphenols, the calibration statistics were also very good (R2>0.86). In wines aged in French and in American and French oak barrels, and in “reserva” and “gran reserva” wines, the RPD was higher than 1.5 in all the compounds. For haloanisoles and halophenols, favourable calibration results were obtained (R2>0.77). The RPD values over 1.5 were obtained for “reserva” and “gran reserva” wines as well as for three of the four zones. Consequently, NIR spectroscopy can be used as a rapid tool to determine fermentative volatile compounds, oak volatile compounds, ethylphenols, haloanisoles, and halophenols in wines.

Fourier Transform Infrared (FTIR) spectroscopic imaging and mapping techniques have become essential tools for the detection and characterization of the molecular components of biological tissues and the modern analytical techniques enabling molecular imaging of complex botanical samples. These techniques are based on the absorption of IR radiations by vibrational transitions in covalent bonds and their major advantage is the acquisition of local molecular expression profiles, while maintaining the topographic integrity of the tissue by avoiding time-consuming extraction, purification and separation steps. These new techniques enable global analysis of biological samples with high spatial resolution and provide unique chemical-morphological information about the tissue status. With these non-destructive examination methods it is possible to get qualitative and quantitative information of heterogeneous samples. In this paper recent applications of infrared spectroscopic imaging and mapping technologies of plant material are described.

The application of IR spectroscopy in herbal analysis is still limited when compared to other areas (food and beverage industry, microbiology, pharmaceutical etc). The aim of this work is to adopt the fingerprinting through Fourier Transform Infrared (FTIR) technique to measure the polyphenols of six seagrasses of Gulf of Mannar, India. The representative IR spectra from the mid-infrared region (4000-400 cm-1) for aqueous methanolic extract of seagrasses were observed. Samples of six seagrasses in the region of polyphenols showed slight variation in bands than the standards. Noticeably the presence of wavelength numbers of FTIR spectra of Gallic acid at 669, 763, 1025, 1100 and 1654 cm-1, Tannic acid at 669, 860, 1172, 1511 and 1627 and p-Coumaric acid at 669, 1124, 1171, 1508 and 1638 cm-1 were also observed in all seagrasses analysed. Wavelength FTIR spectra corresponding for Vanillin was 668, 1498, 1534, 1617, 1654 and 3392 cm-1, among them 668 cm-1 is present in all the seagrass and 1498, 1534, 1617 and 1654 cm-1 were present in H. pinifolia alone. This is the first study that proves FTIR technique is an efficient tool for measuring polyphenols in seagrasses.

Previously, we showed that extracts of ripe seasonal sweet corn tassels possess anti-irritant and anti-oxidant activities. The chemical identification of corn tassel bioactives was investigated by HPLC analysis. The hydroalcoholic extracts are composed primarily (>85%) phenolic-type compounds. The predominant component from C18 columns were concentrated by reverse phase chromatography and purified to greater than 97-99% by preparative HPLC chromatography. The chemical was determined by mass and NMR spectrometry to be 4-hydroxy-1-oxindole-3-acetic acid (Tasselin A) with a M.W of 207 daltons. Purified Tasselin A inhibits melanin production in sporulating cultures of the common bread mold. An anti-tyrosinase enzyme assay showed that it inhibits mushroom tyrosinase enzyme (IC50 = 0.75mM), and has both antioxidant, and skin anti-irritant activities. There are no prior reports of bioactives derived from corn tassels with potential skin whitening activity, nor are any corn tassel bioactivities currently employed as ingredients in personal care or skin care products.