The review, published in Flavour and Fragrance Journal, provides an overview of the history of sweet compound discovery, giving examples of some compounds that have been discovered and then ‘forgotten’, including Sweet Dihydrochalcone Acid Derivative, Osladin, Hernandulcin, and Monatin.
The researchers noted that in light of new developments in analytical tools and better knowledge in the area of structure and function, compounds that have been ‘forgotten’ by new research should be re-assessed, noting that their contribution to sweet taste chemistry could still offer a lot in future research into sweeteners and sweet taste.
“Many compounds have been described in the literature as sweet, but several of them – after a short period of popularity – were apparently ‘lost’ or ‘forgotten’, without any further development … What about them?” said the authors, led by Dr Angela Bassoli from the University of Milan, Italy.
“We believe that many old and new molecules still have much potential in sweet taste research; these and many other valuable items are waiting to be claimed by young chemists at the ‘Lost & Found’ science office,” they said.
Sweet discovery
Bassoli and her colleagues noted that with the exception of a few natural sweet sugars that have always been known, “the discovery of new sweet compounds has been mainly serendipitous.”
“Between 1965, the year of the discovery of aspartame, and year 2000 we can roughly define an era of ‘rational design’,” they said.
The researchers noted that between these years, much research focused on classical structure–activity relationships to develop or identify new and more potent analogues from a known lead molecule. This research produced a large number of new compounds from a range of chemical families which have since been synthesised and analysed.
However, post year 2000, new information about taste receptors and their mechanism of action began to be elucidated, they noted.
“In a few years a large amount of new information emerged, which dealt with taste receptors, … taste, olfaction and other sensing mechanisms, taste and nutrition,” said the Bassoli and her colleagues.
Forgotten molecules
“Among all molecules that have been isolated and synthesized, only a few have successfully reached the final goal of commercial development,” said the authors.
However, they noted that there are a great number of “very interesting compounds of natural or synthetic origin that – after a short period of popularity – were apparently lost or forgotten, without any further development.”
The review gives examples of several sweet compounds which fit this description, including Sweet Dihydrochalcone Acid Derivative, Sweet Benzoylbenzoic Acid Derivative, Sweet Gibbane Derivative, Osladin, Hernandulcin, and Monatin.
Referring to the example of Osladin, the Italian research team said:
“Osladine is a naturally occurring, high potency sweetener from the rhizome of Polypodium vulgare. It is a saponin glycoside 500 times more potent than sucrose. Despite the growing interest for natural sweeteners, osladin has never achieved the success that might have been anticipated.”
“In this case the most likely reasons are the low availability of the natural source, a fern growing in cold climates; the fact that the active principle is the rhizomes and not in the leaves; and of course the complicated structure that prevents the design and a high yield synthesis of the compound,” they said.
The authors noted that some of these less common and often forgotten sweet compounds are still the object of research, “and could find new and innovative applications …thanks to the rapidly increasing knowledge in the biological mechanisms underpinning gustation and somatosensory perception.”
Sweetener conference
Some of these issues, and many more, will be discussed at the upcoming International Sweeteners Association (ISA) meeting on May 19 in Brussels. For more information click here.
Source: Flavour and Fragrance Journal
Published online ahead of print, doi: 10.1002/ffj.206
“Lost and found in sweeteners: forgotten molecules and unsolved problems in the chemistry of sweet compounds”
Authors: A. Bassoli, G. Borgonovo, G. Morini