Natural products quantification

Depending upon the experimental design, the purpose of the experiment, and the nature of the mRNA template used to program the translational systems, different types of product quantification should (or could) be used. Aside from the quantification of the luciferase synthesized, which is carried... 

Online LC-MS is a good solution for separation, identification, and quantification because it permits the confirmation of polar and nonvolatile compounds without need for derivatization.4 The use of LC-MS for biological sample detection and data analysis has grown rapidly during the past few years. Many reliable and easy to use LC-MS systems are commercially available and have been adapted for solving analytical problems by scientists in proteomics research, metabolic study, complex natural product separation and characterization, and drug discovery. 

Artemisinin, a tetracyclic 1,2,4-trioxane isolated from Artemisia annua L., is currently recommended as a first-line agent against Plasmodium falciparum malaria. Artemisinin and its synthetic derivatives have also been shown to be promising prototypes for the development of new antiproliferative agents. This chapter presents the recent advances on the analytic methods for extraction and quantification of artemisinin from A. annua plants as well as the biological properties of this natural product. 

In the Orient, numerous natural products have long been used in folk medicine. Also, in recent years some pharmaceutical industries and universities in Korea are placing their efforts on the quantification of cytotoxic phytochemicals from the natural resources. As a part of those efforts, the present authors are involved on the two-fold critical evaluations of the possible implementation of the supercritical fluid extraction(SFE) to obtain extracts from the natural resources one is the establishment of the optimum SFE condition for each sample resource which gives maximum extraction yield and cytotoxicity, and the other is the high-purity isolation of some specific compounds from the SFE total extracts. 

The use of pyrolysis GC-MS is still not common in the analysis of biopolymers and biocomposites because of the large quantity of parameters to be controlled for the development of a method. It is not easy, in a dynamic system, to transfer from a flow of inert gas (Pyr-GC) to vacuum conditions (MS). On the other hand, quantification is based on the fact that degradation is ion-specific, and that a given substance always produces the same fragments. This is not the case with biopolymer additives, especially in natural products, where fragmentation can proceed in several directions. This requires the use of internal standards and multiple measurements of each sample. Therefore a complete quantification requires considerable time and effort. 

E. Tenailleau, P.Lancelin, R.J. Robins, S. Akoka (2004 a) NMR approach to the quantification of nonstatistical distribution in natural products vaniUin. Anal. Chem. 72, 3818-3825... 

Modern spectroscopic techniques have revolutionized compound identification and quantification. Only a few decades ago, identification of a structurally complex natural product would require multigram quantities of isolated material, which would then be subjected to series of derivatization and degradation experiments, aiming to deduce the unknown s structure from that of resulting derivatives or fragments that may represent known compounds. As a result of the tremendous advances in sensitivity and resolution of NMR spectroscopy over the past 30 years, identification of microgram quantities of new compounds has now become routine. For example, the structure of the polyketide antibiotic, erythromycin (1), was identified in 1957 only after extensive chemical and spectroscopic studies based on multigram amounts of isolated compound.1-3 By the time its... 

NMR spectroscopy is one of the cornerstones of modern natural products research and is used routinely to monitor compound purity through the isolation procedure and to determine the structure of novel bioactives. NMR also has a long history of use in metabolism studies utilizing proton and phosphorus nuclei in both liquid and solid states and in vivo and in vitro. More recently, NMR has been applied in metabolomics (or metabonomics) for metabolite profiling, quantification, and structure elucidation.4... 

The following comments are directed primarily to the issue of quantification. Clearly, however, this presupposes that the analyte has been identified, and can be separated, so that these techniques — especially preparative HPLC — have found wide application in the cleanup of environmental samples. It is worth pointing out that the problem of separating and identifying natural products that may exist as complex mixtures in low concentrations has taken advantage of many of these techniques, and indeed was the motivation for their development. The combination of complex mixtures and low concentration of analytes is characteristic of most environmental samples, so that advantage should be taken of these methods on a wider basis. 

A survey of literature gave over 20 papers where 2D NMR experiments was successfully applied in quantification of complex samples. The selection of the used experiments was also quite diverse all typical 2D homo- and heteronuclear correlation experiments were among them. Many of the authors also compared the 2D NMR results against ID NMR quantification or quantification with other analytical technique. In overall, 2D NMR quantification offered a better linearity and accuracy in these comparisons due to better resolved peaks. Additionally, the approach often facilitated analysis of minor components that were not distinguishable from ID NMR spectra. The main part of the papers that demonstrated 2D NMR quantification focused on the analysis of natural products like animal and plant metabolites. Some articles were also found where quantitative 2D NMR was applied to quality control in food industry, and on characterization of the products of oil industry. The following sections give a short summary of the quantitative 2D NMR on the aforementioned topics. 

Since its introduction at the end of the 1950s, gas chromatography (GC) has developed into a versatile tool in the analysis of natural products. Clear advantages of GC are the high resolution and high sensitivity of the most common detection method, the flame ionization detector (FID), and the fact that the detector response of similar compounds will be about the same, i.e., peak areas may be directly compared for quantification. This is in contrast to high performance liquid chromatography (HPLC), in which the detector response in the most common detection mode, ultra violet (UV)"absorption, may vary widely for different compounds since the molar extinction coefficients can be very different. 

In the 50 years since its introduction, the use of GC by the petroleum industry has helped foster many breakthroughs in GC instrumentation. Open-tubular GC columns and the theory that describes them were first introduced by Golay and Ettre in the mid-1950s. The further development of open-tubular capillary columns was done by Desty of British Petroleum, and, with subsequent refinement, this technique is now the standard method for most GC applications. The use of GC for sample analysis was also quickly adopted by the pharmaceutical and food industries and is used for fundamental studies of reaction kinetics and physiochemical measurements. Today the use of GC for the analysis of complex samples such as serum proteins, natural products, essential oils, and environmental samples has become a routine with multidimensional separation techniques and multivariate chemometric analysis providing identificatimi and quantification of trace analytes from complex samples in the sub-ppb range. A GC system usually consists of the following elements (Fig. 1) ... 

LC-MS is applied in many other fields as well, e.g., in the study of natural products, such as in the dereplication of flavonoids and several other compound classes in plant material and the identification and quantification of natural toxins, of endogenous compounds like acylcamitines and arachidonic acid metabolites, and DNA adducts. LC-MS has become a routinely applicable technique. It is rapidly entering the chromatography laboratories to act as an LC detector in a variety of analyses. As such, LC-MS is appreciated for its sensitivity and selectivity, its specificity, and the information obtained, e.g., on the molecular mass of the analyte. The operation of an LC-MS system is no longer reserved to the MS specialist. 

Powerful new technologies of ion analyses (tandem MS, time-of-flight MS (TOF MS), and ion-trap MS) substantially increased the capability of MS analyzers with respect to specificity and the extent of data handling. The range of applications of LC-MS in the field of natural products is constantly increasing, especially with the introduction of tandem MS (MS/MS) for quantification and high resolution MS (HRMS) for unequivocal structural elucidation using mass accuracy and the elemental composition of precursors and product ions. 

Tanaka H, Shoyama Y (1998) Development of ELIS A-analy sis methods for the quantification of bioactive natural products in plants, phytomedicines and in humans or similar. Phytomedicine 5(5) 397-415. doi 10.1016/s0944-7113(98)80023-8... 

Recently, use of a MS as a detector for profiling and quantification of natural products was used for high sensitivity and selectivity [61], GC-MS has been used successfully to specifically identify and quantify plant hormones with high sensitivity. Although the sample preparation process has been simplified by use of vapor-phase extraction, GC-MS analyses typically require several steps of extraction, purification, and chemical derivatization before analysis [62],... 

The developers concluded that LipidBlast could be successfully applied to analyze MS/MS data from over 40 different mass spectrometer types and used with other available search engines and scoring algorithms, which represents a paradigm shift in lipidomics because it is not feasible to chemically synthesize all metabolites or natural products as authentic standards for library generation or quantification purposes. Moreover, the current array of MS/MS mass spectra for plant, animal, viral, and bacterial lipids in LipidBlast could be readily extended to many other important lipid classes. 

As the derived shape of the logistics customer service-revenue curve is of qualitative nature, a quantification of that relationship is called for. The exact curve progression is determined by surrounding conditions like product, customers, industry or company (Hsin-Hui et aly 2009 112, 121 ). The below introduced fuzzy-based model ascertains the curve progression considering these fEictors. 

HPLC is a technique in analytic chemistry used to separate the components in a mixture, to identify each component, and to quantify each component. HPLC has been used for medical, legal, research, and manufacmring purposes. HPLC has been widely used for both separation and quantification of natural products (NPs) from the active fractions ofTCMs [18-22]. The efficiency of HPLC analysis and preparation might be affected by many factors, including different support materials in the column, mobile phase, and others [23]. This chapter describes purification of bioactive molecules from TCMs based on bioassay-guided isolation integrated with SEC and HPLC preparation approaches. 

Recent concerns about soil erosion and its effects on crop productivity have not been matched by reliable information abont the actnal extent and intensity of the process or, more accurately, about soil losses in excess of natural denudation. Quantification of these impacts is complicated by the fact that in some areas much of the eroded soil is not lost to food production very littie or no eroded sediment leaves the fields in areas with gentle relief without any major surface oudet, and when the sediment leaves the land most it may be deposited downstream as colluvium or alluvium. ... 

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