Chemistry Blog

«

»

Feb 20

A Brief Analysis of Truvia

by Jeremy | Categories: science news, synthetic chemistry | (23497 Views)

1

On December 18, 2008, the Food and Drug Administration ruled the natural sweetener Truvia “generally safe” for use in foods and beverages. Truvia (trade name Rebiana) is comprised of a diterpene called steviol glycoside, which is isolated from the extracts of the leaves of the plant Stevia rebaudiana bertoni.  The herb Stevia—basically the leaves of the plant—has been available for years, so steviol glycoside is nothing new, per se.  Cargill Food and Ingredient Systems now markets Truvia as a singular, “fully-characterized product” (Stevia, by comparison is a witch’s brew of anywhere from 40 to 200 compounds).  More interesting data about Truvia can be found here.  As a result of the FDA’s ruling, Coca-Cola Company will soon launch a new line of reduced-calorie drinks with the most prominent being a new version of Sprite called Sprite Green (comes in a nifty aluminum can).

Stevia was purportedly discovered by Moises Santiago Bertoni in 1887 while exploring the forests of Paraguay—Stevia rebaudiana‘s natural habitat (see: Econ. Bot. 1983, 37, 74-82).  Additionally, the plant had been identified in Korea, China and Japan (J. Med. Chem. 1981, 24, 1269–1271).  Word spread about the plant and eventually Stevia made its way to the US (courtesy of the Department of Agriculture) in 1918 due to the growing interest in its strong sweetness.  A wide array of physiological studies determined that the sweet sensation of Stevia derives from the presence the compound steviol glycoside.  Since then, several studies have been reported on its structure and function of steviol glycoside including stereochemical analysis (J. Am. Chem. Soc. 1963, 85, 2305–2309) and metabolic analyses (J. Agric. Food Chem. 2006, 54, 2794–2798).

In the spirit the Truvia saga, I figured that I’d cover its first total synthesis of steviol methyl ester, which Mori and co-workers first reported (Tetrahedron Lett. 1970, 11, 2411-2414).  Starting from the tricyclic methyl ester, Mori protected the aldehyde then installed ketone by way of a hydroboration-oxidation and ensuing Jones oxidation.  Deprotection of the dioxolane was accomplished using aqueous acid in acetone followed by tandem acid-catalyzed aldol addition to furnish the 1,3-ketol, which was converted to the 1,3-dione via second Jones oxidation.  Clemmenson reduction afforded the 1,2-ketol (I encourage you to push the arrows for that transformation), which was converted to the allylic alcohol by methylenation. 

2

As is the case with most “new” sweeteners, Stevia has been the subject of criticism over toxicological effects.  One study, conducted by John Pezzuto and co-workers at the University of Chicago, concluded that steviol is actually metagenic (PNAS 1985, 82, 2478-2482).  However, the asterisk to this scientific study—“steviol is mutagenic toward S. typhimurium strain TM677” and not human cells—should clearly be taken into consideration when weighing the toxicity of the supplement as a whole.  Just so we’re all on the same page, the “S” in “S. typhimurium” stands for salmonella—a bacterium. 

All in all, I think it’ll pretty interesting to watch more information about Truvia find its way into the public eye. 

10 comments

Skip to comment form

  1. Stevia - Mike Silver

    Hi Awesome Mitch

    I’ve been following Stevia in Google trends for quite a while now. My interest is personal – Stevia is about the ONLY sweetener I regularly use because I tolerate it well.

    If you look at the search volume graph, you can see that there is a real breakout to the upside happening.
    Google Stevia Search Trends

    As a result of the explosion of interest, I’ve put up a website about the latest at stevia at Stevia News

    Enjoy.

    - Mike

  2. Chemjobber

    This is an interesting molecule — so’s the marketing. It looks pretty benign, but that exocyclic methylene might be troublesome… maybe?

  3. dr.umesh

    Hi Mitch,

    Thanx, for the interesting info.Keep it going….

    1. mitch

      It wasn’t me. ;)

      1. Jeremy

        About that.. I tagged “Mitch is Awesome” ’cause I was feeling silly. It happens.

  4. ChemSpiderMan

    I think the stereochemistry got mixed up between the bottom left structure and your top right structure (with steviol written under)?

    1. Will

      Yeah, the stereochemistry of that methyl group in the bottom left structure is wrong. It should be beta (toward you), not alpha (away from you) as depicted in the bottom left structure. I believe the stereochemistry of the bridging methylene and 7-membered ring, as depicted in Mori’s synthetic route, is correct.

  5. Carlos Kelly

    the thing i like about stevia is that it is tooth friendly’;`

  6. Bradford

    Carlos, I believe it is just as tooth friendly as any other artificial sweetener. The effect is derived from the difficulty of a bacteria using them as a food source as they would simple sugars. With bacteria unable to ferment these molecules in their metabolism, they don’t create an acidic environment which is with a high sugar meals. The acid is what inhibits remineralization and thus tooth decay.

  7. Ryan Crain

    Too much sweets is not healthy :)

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>