New tools for bioactive oligomeric ellagitannins

MSc Nicolas Baert from the Natural Chemistry Research Group (http://naturalchemistry.utu.fi) defended his doctoral thesis on August 18. The excellent doctoral training Nicolas enjoyed during the LegumePlus project has already paid off, since Nico travelled to Turku from the Cornell University, New York, where he holds his new post-doc position.

Prof. Garry Waghorm (Massey University, New Zealand) was the opponent to MSc Nicolas Baert, prof. Juha-Pekka Salminen was the custos and Dr. Maarit Karonen the other supervisor.

It is perhaps a matter of opinion what was the most significant result of the PhD work by Nicolas Baert. The thesis contained three excellent papers and the fourth study was included as a submitted manuscript. For me it is really difficult to choose only one of the three papers so I choose differently. I think the most significant result was the growing of a French student from the stage where doing a PhD was not necessarily an option, via the flourishing and all the way shining experiences with the Marie Cuire ITN “LegumePlus” to the stage where a scientist was born and finally a post-doc position was guaranteed even before the PhD was finalized. This journey as a whole, with all the wonderful events taking place with the family as well, was a great success. And I do think that the Wageningen results as a whole were amazing :).

Purification and quantification of the rare macrocyclic ellagitannin oligomers

Nicolas tested the drink made especially for him from the flowers of Nicolobium doctorifolium. UPLC-MS/MS fingerprints reminded surprisingly much of those polyphenols found in fireweed, or willowherb, or … :).

We knew before Nico’s PhD that species in the family Onagraceae are able to produce the largest ellagitannins ever detected in plants. Nico managed to purify and accumulate these rare tannins even up to heptamers making our research group thus the first group ever purifying ellagitannins larger than pentamers. He actually “purified” also larger ellagitannins to the level (a mixture from octamers to at least undecamers) that would be often accepted as a true purification process, if the tannin class was proanthocyanidins :). But for hydrolysable tannins the limit still remained with the heptamers. We are excited to find new limits soon, with any class of tannins.

Although we may be moving as a group towards the more efficient use of HR-MS in the quantitative analysis of tannins, it was a major achievement from Nico to publish also quantitative MRM methods for all the tellimagrandin I based oligomers from dimers to heptamers. This method now allows anyone to detect and quantify these rare tannins from any plant species producing these. This is important, since the levels of largest oligomers are often so low that they cannot be found or detected without selective and sensitive analysis methods. We are left waiting if the methods find use for others as well.

Well, Nico certainly used his method efficiently to witness how the oligomers were distributed in different organs, individuals and populations of Epilobium angustifolium. In my opinion the most striking finding was the population-specific ratio between the main oligomers, i.e. oenothein A to oenothein B. This same ratio was earlier found to be the main chemical explanatory factor for us to differentiate between genotypes of Oenothera biennis, another excellent oligomer-producing species of the Oenagraceae. It was exciting to find something similar with E. angustifolium as well, although none of these individuals were able to accumulate oenothein A in the same manner as O. biennis.

Link to the method paper: http://doi.org/10.1016/j.chroma.2015.09.050
Link to the population study: http://doi.org/10.1016/j.phytochem.2016.11.003

Farewell to methanogens by large oligomers and wellbeing to ruminants by the intermediate ones

In the big picture the Wageningen results were truly significant. It is quite rare to get such logical, but yet unexpected results. Now we are aware of the oligomer size required for tellimagrandin I based macrocyclic ETs that both decrease the action of the methanogens and thus methane emissions of the ruminants and increase the concentration of crucial volatile fatty acids that ruminants may use as an energy source. To obtain a more precise interpretation of the results, please look for the paper at http://doi.org/10.3168/jds.2016-11069 and thesis at http://urn.fi/URN:ISBN:978-951-29-6908-1.

Nico’s evening party will be perhaps remembered for a long time for the wrong reasons due to one disturbed, sad and pathetic individual hitting the Turku city center during the same day. We will remember it for the good atmosphere, friendship, and nice talks that covered the whole library of emotions from tears to sheer laughter :). We must be grateful to Garry Waghorn for making Nico’s day a really special one, since it was not an easy journey for the world famous ruminant expert to travel all the way from New Zealand to Turku. We hope this was a nice experience to Garry as well, although our cows certainly were of smaller size in comparison to those found in Garry’s hometown :).

Juha-Pekka Salminen