WS1490 was a synthetic version of a kavalactone called kavain.  It was
combined with a full-spectrum, natural kava extract to form a product
called Laitian (sp) 100.  Synthetic kavalactones (or more correctly,
pyrones) have been around for about 20 years, but always showed poor
results in clinical trials compared with the natural extracts.  The German
pharmaceutical manufacturer of WS1490 and Laitian 100 claimed that the
problem with the synthetics is that they have a very poor bioabsorption
rate, and that, for reasons not ascertained, when combined with the
full-spectrum of kavalactones, the absorption rate increases dramatically.
So in effect, they "turbo-charged" a natural kava extract with additional
kavain; about 60% synthetic to 40% natural (or thereabouts).

To my knowledge, synthetic kava products were only sold in Europe. The
herbal manufacturers horned their way into the market claiming that "all
natural" is best; they even tried to get the proposed bans to apply only to
synthetic kavalactones.  I do not believe that WS1490 is manufactured
anymore because of all of the European bans on kava products.  It took me a
long time to track this info down, and finally found it only in cached web
pages written in German.

IMO, if/when kava is rehabilitated after the liver damage scare, there is a
tremendous opportunity for an OTC pharmaceutical company in developing an
extremely effective and safe anxiolytic drug.  If I only had a few million
dollars to spare......

Figaro