Plant-derived sweetening agents: saccharide and polyol constituents of some sweet-tasting plants.

Samples of the sweet-tasting species Acanthospermum hispidum DC. (Compositae) (aerial parts), Boscia salicifolia Oliv. (Capparidaceae) (stem bark), Hovenia dulcis Thunb. (Rhamnaceae) (peduncles) and Inga spectabilis Willd. (Leguminosae) (arils) were acquired as part of a continuing search for high-intensity natural sweeteners of plant origin. Following their preliminary safety evaluation, the sweetness of these plants was traced to large amounts of sugars and polyols by taste-guided fractionation, which were identified and quantified using gas chromatography/mass spectrometry. The combined yields of sugars and polyols in the A. hispidum, B. salicifolia, H. dulcis, and I. spectabilis samples investigated were 6.9, 10.1, 18.4 and 12.1% w/w, respectively. These yields are much higher than the total saccharide and polyol content (2.4% w/w) of the sweet dried fruits of Thladiantha grosvenorii (Swingle) C. Jeffrey (Cucurbitaceae), a species which has previously been reported to contain more than 1% w/w of the intensely sweet triterpene, mogroside V. The dried leaves of Symplocos tinctoria (L.) L'Hérit. (Symplocaceae), which were not appreciably sweet, were found to contain only 2.0% w/w of sugars. The results of this investigation, therefore, suggest that unless the saccharide and/or polyol content of a plant part is well over 5% w/w, then it is unlikely to exhibit an overtly sweet taste, unless an intense sweetener is present.

Anti-inflammatory and antinociceptive activities of Loasa speciosa in rats and mice.

In the range of doses of 250-500 mg/kg (given i.p.) the aqueous extract of Loasa speciosa leaves showed an inhibitory effect on leukocyte migration, and a reduction on the pleural exudate, as well as dose-dependent anti-inflammatory and peripheral antinociceptive activities.

Mortality supposedly due to intoxication by pyrrolizidine alkaloids from Heliotropium indicum in a horse population in Costa Rica: a case report.

This article describes a case of massive mortality among horses which was probably due to intoxication by pyrrolizidine alkaloids from Heliotropium indicum. Over 4 years more than 75% of a population of about 110 horses on a farm in Costa Rica died after showing nervous neurological symptoms. Two clinical manifestations were encountered, an acute and a chronic one, both with a fatal outcome. Pathological findings in 2 horses coincided with those reported in the literature for intoxication by pyrrolizidine alkaloids and were not specific for VEE. However Venezuelan equine encephalitis (VEE) was the main differential diagnosis and could not completely be excluded because this disease was endemic in the region and VEE titres were found to be high. Taxonomic and toxicological investigations implicated Heliotropium indicum as the most probable principal cause of the intoxication.

Volatile constituents of Cunila polyantha (Lamiaceae) from Costa Rica. A rich source of menthone.

The constituents of the volatile oil of Cunila polyantha from Dota, Costa Rica, were investigated using coupled gas chromatography-mass spectrometry (GC-MS) analyses. Menthone (63%), pulegone (14%), beta-caryophyllene (4.5%) and 3-octanyl acetate (3%) were found to be the major constituents of the volatile oil.

Anti-inflammatory activity of aqueous extracts of five Costa Rican medicinal plants in Sprague-Dawley rats.

The anti-inflammatory properties of Loasa speciosa and Loasa triphylla (Loasaceae), Urtica leptuphylla and Urera baccifera (Urticaceae), and Chaptalia nutans (Asteracene) were studied using the carregeenan induced rat paw edema model. Aqueous extracts of each plant were made according to the ethnobotanical use. The hippocratic assay was made with female rats; the dose used was 500 mg/kg i.p. and the control group received 0.5 ml of n.s.s.. All the animals treated showed hypothermia, and those treated with the extracts of Chaptalia nutans, Urera baccifera and Urtica leptuphylla showed an increased colinergic activity. Acute toxicities of the aqueous extracts were studied in mice an the mean lethal doses ranged between 1.0226 and 1.2022 g/kg. The extracts of Urera baccifera, Chaptalia nutans, Loasa speciosa and Loasa triphylla (500 mg/kg i.p.) showed an anti-inflammatory activity comparable with that of indomethacin. The extracts of U. baccifera and C. nutans, which showed the greatest anti-inflammatory activity, did not show it when used orally (500 mg/kg p.o.).

Essential oil of Lepechinia schiedeana (Lamiaceae) from Costa Rica.

The composition of the essential oil isolated by steam distillation from aerial parts of the Costa Rican herb Lepechinia schiedeana (Schlecht) Vatke (Lamiaceae) collected in El Empalme, Costa Rica, was determined by capillary gas chromatography (GC) and coupled gas chromatography-mass spectrometry (GC-MS) analyses. Fifty-one components were identified corresponding ca. 93% of the oil. The major components were beta-pinene (26.6%), cis-pinocamphone (25.1%), delta-3-carene (6.1%), trans-pinocamphone (4.0%), camphor (3.8%) and beta-caryophyllene (3.7%).

Antimalarial activity of tropical Meliaceae extracts and gedunin derivatives.

Extracts of 22 species of Meliaceae were examined for antimalarial activity using in vitro tests with two clones of Plasmodium falciparum, one sensitive to chloroquine (W2) and one chloroquine-resistant (D6). Twelve extracts were found to have activity, including extracts of Cedrela odorata wood and Azadirachta indica leaves, which contained the limonoid gedunin. These extracts were more effective against the W2 clone than the D6 clone, suggesting there is no cross-resistance to chloroquine. Gedunin was extracted in quantity, and nine derivatives prepared for a structure-activity study, which revealed essential functionalities for activity. The study also included four other limonoids derived from related Meliaceae. Only gedunin had better activity than chloroquine against the W2 clone. This active principle could be used to standardize a popular crude drug based on traditional use of A. indica in West Africa.

Costaricine, a new antiplasmodial bisbenzylisoquinoline alkaloid from Nectandra salicifolia trunk bark.

A MeOH extract of Nectandra salicifolia trunk bark, obtained during a diversity-based plant collection in a lower montane rainforest in Costa Rica, showed activity in an in vitro antiplasmodial assay measuring incorporation of [3H]-labeled hypoxanthie by Plasmodium falciparum. In addition to 15 known alkaloids isolated from samples of trunk bark, roots, and leaves/twigs of this species, a new bisbenzylisoquinoline alkaloid (+)-costaricine [(+)-12-O-methyllindoldhamine] (1) was isolated from bark (0.038% yield) and from roots (0.001%). (+)-Costaricine was active in the antiplasmodial assay, with IC50 values of 50 ng/mL vs. the chloroquine-sensitive D6 clone and 294 ng/mL vs. the chloroquine-resistant W2 clone of P. falciparum.