The intensely sweet herb, Lippia dulcis Trev.: historical uses, field inquiries, and constituents.

Lippia dulcis Trev. (Verbenaceae) is the source of hernandulcin, the first known intensely sweet sesquiterpenoid, a compound which is a volatile oil constituent. The literature on the uses of this species, dating back to early colonial times in Mexico, has been examined. This plant began to be used as an official drug in the late 19th century for the treatment of coughs and bronchitis, and at that time preliminary phytochemical investigations were undertaken. Field work carried out in Mexico in 1981 and 1982 has indicated that there is still an active trade involving L. dulcis, which is sold primarily in market places for its alleged abortifacient activity. We have obtained no evidence, either from the literature or from field inquiries, that L. dulcis has ever been used for sweetening foods or beverages. Fourteen L. dulcis volatile oil constituents, mainly mono- and sesquiterpenoids, were identified by gas chromatography/mass spectrometry. The toxic compound, camphor, was found to constitute 53% w/w of the volatile oil of this species. The potential use of L. dulcis for the extraction of hernandulcin is discussed.

Hernandulcin: an intensely sweet compound discovered by review of ancient literature.

Ancient Mexican botanical literature was systematically searched for new plant sources of intensely sweet substances. Lippia dulcis Trev., a sweet plant, emerged as a candidate for fractionation studies, and hernandulcin, a sesquiterpene, was isolated and judged by a human taste panel as more than 1000 times sweeter than sucrose. The structure of the sesquiterpene was determined spectroscopically and confirmed by chemical synthesis. Hernandulcin was nontoxic when administered orally to mice, and it did not induce bacterial mutation.