A. D. Kinghorn

Potential sweetening agents of plant origin. II. field search for sweet-tastingStevia species

Field work in Paraguay, Peru, Colombia and Mexico, including field organoleptic tests and interviews, was carried out in search of sweet-tasting Stevia species. Results of such tests performed on at least 31 species, as well as ethnobotanical data on 9 species, are presented. The data obtained showed that leaves of no other Stevia species studied possessed a potent sweet taste comparable to that of S. rebaudiana leaves. Since only 15% of the approximately 200 known species in this genus were investigated in this study, it is quite possible that further research may reveal additional sweet-tasting Stevia species.

Effect of tannins on screening of plant extracts for enzyme inhibitory activity and techniques for their removal

Ethyl acetate and aqueous extracts of tannin-containing topoisomerase inhibitory plant samples were subjected to one or more of seven tannin removal procedures, and the resulting products were subsequently evaluated for topoisomerase inhibitory activity. In most of the samples investigated, the initial activity was lost after tannin removal. It was concluded that the activity initially observed was primarily due to tannins. Procedures are presented for routinely obtaining tannin-free organic and aqueous fractions.

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.

Sweetening agents of plant origin: phenylpropanoid constituents of seven sweet-tasting plants

Field inquiries and organoleptic tests for sweet taste led to the procurement of samples ofPiper marginatum (dried leaves),Tagetes filicifolia (fresh whole plants),Osmorhiza longistylis (fresh roots),Foeniculum vulgare (fresh aerial parts),Myrrhis odorata (fresh whole plants),Ocimum basilicum (fresh aerial parts), andIllicium verum (dried fruits). Follow-up laboratory studies of the leaves ofPiper marginatum demonstrated that trans-anethole (a phenylpropanoid) was the major sweet constituent of this species. In the remaining six species, GC/MS analysis also enabled us to demonstrate that sweetness is attributable, in each case, to the presence of high concentrations of the phenylpropanoids, trans-anethole and estragole, either alone or in combination.ResumenEntrevistas y busqueda en el campo seguidas por pruebas organolépticas para detectar el sabor dulce nos dirigieron a la adquisición de muestras dePiper marginatum (hojas secas),Tagetes filicifolia (plantas enteras secas), Osmorhiza longistylis (raices frescas),Foeniculum vulgare (partes aéreas frescas),Myrrhis odorata (plantas enteras frescas),Ocimum basilicum (partes aéreas frescas), eIllicium verum (frutas secas). Estudios de laboratorio posterioresde las hojas dePiper marginatum demostraron quetrans-anetol (un fenilpropanoide) fué el principio edulcorante mayor de esta especie. En las seis especies restantes, el análisis por medio de la cromatografía gaseosa y espectrometría de masa nos permitieron a demostrar que el sabor dulce se debe tambien, en cada caso, a la presencia de altas concentraciones de fenilpropanoides, a sabertrans-anetol y estragol, tanto sólo como en conjunto.

Agrostistachin, a novel cytotoxic macrocyclic diterpene from

Abstract Agrostistachin, a cytotoxic constituent of Agrostistachys hookeri , was characterized as a new member of the rare casbane class of diterpenoids. The structure and stereochemistry of this compound were established by analysis of its spectral and X-ray crystallographic parameters.

Analysis of structural features responsible for the sweetness of the sesquiterpene, hernandulcin

The relationship between sweetness and structure was studied for several analogues of the intensely sweet sesquiterpene, hernandulcin. These derivatives were prepared synthetically, and were subjected to spectroscopic and conformational analysis. With the exception of the parent substance, none of the derivatives tested proved to be sweet. Evidence gathered in this study suggests that hernandulcin binds to its putative receptor through a three-point interaction, involving the C-1 carbonyl and C-1′ hydroxyl groups, and the double bond between C-4′ and C-5′. In the course of a preliminary safety assessment, the 3-desmethyl derivative of hernandulcin was found to be mutagenic towardSalmonella typhimurium strain TM677.

10α-hydroxymethylsparteine, a new type of quinolizidine alkaloid from Genista sessilifolia

10α-Hydroxymethylsparteine (1), a novel type of quinolizidine alkaloid with a 16-carbon atom skeleton, was isolated from the aerial parts of Genista sessilifolia DC. The position of the hydroxymethyl substituent and the stereochemistry of compound 1 were established by analysis of its spectroscopic data.