Nowadays many researchers do NMR of plant fractions, but does it give any useful information? I am having active plant fraction. Should I go for NMR? Is it worth doing it?
I don't think a NMR can give useful information about the fraction as fraction may contain lot of constituents
Each compound has got a different set of NMR data from an other compound. It's more true if you are recording 13C NMR spectra. You will probably have a mixture of compounds, it means at least 200 chemical shifts. But Intensities and shifts will give some really interesting informations. You can deduce if there are fatty acids, terpens, sterols, flavonoids really easily and an idea of the amount. With these informations you can figure out if your fractions is interresting and what kind of separation you will have to do. In many case a product isolation and a molecular weight will be helpfull to give a structure of the molecule.
plant fractions NMR some extents it may help such as aromatic compounds( aromatic region ) or non aromatic (non aromatic region ) compounds but NMR spectra very complex and difficult to identify the compounds
It depends on how pure the fraction is. If the fraction is very clean, you'll get useful information. If not, one can't say if the chemical shifts are from your active compounds or something else. If the mixture is all related active compunds, you'll just get information about which functional groups are in the family of molecules. My opinion is it is better to wait until one has clean compound since the NMR will be run anyway on the pure material to determine chemical shifts for that compound, integrate the peaks (hard to do with a mixture), and get splitting/connectiviry information.
the used of NMR on crude extract of plant fraction even if it is complicated to interpret, can be very informative about the type of compound you expect from your extract.
It may help you select the best strategy to get to purified compounds or to select your compound of interest.
However, the informations need usually to be completed with HPLC profiling.
here are two examples that can help you :
https://www.researchgate.net/publication/256475634_Cancer_chemopreventive_diterpenes_from_Salvia_corrugata
https://www.researchgate.net/publication/224977244_Acylated_pregnane_glycosides_from_Caralluma_sinaica
Article Cancer chemopreventive diterpenes from Salvia corrugata
Article Acylated pregnane glycosides from Caralluma sinaica
Yes, informative and useful as long as one can follow the classic methods and works suggested by the JK Nicholson or RG Ratcliffe group: http://onlinelibrary.wiley.com/doi/10.1002/1099-0534%282000%2912:5%3C289::AID-CMR3%3E3.0.CO;2-W/abstract,http://jxb.oxfordjournals.org/content/56/410/255.abstract, http://www.ncbi.nlm.nih.gov/pubmed/19551810, http://onlinelibrary.wiley.com/doi/10.1002/pca.1185/abstract, http://www.ncbi.nlm.nih.gov/pubmed/18007604 and so on.
It indeed depends on what information you want to know. It can give you an idea of the classes of compounds contained in the extract. But not to identify products because sometimes just the mixtures of two compounds is not easy to identify.
I agree with Emmanuel Mbosso. NMR spectrum of crude extract of plant fraction, some times, can give valuable information about the class of compounds in the extract and then you can select the best strategy to purify compounds.
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