Karina M. Meragelman

Phytogrowth-inhibitory activities of a clerodane from Viguiera tucumanensis

Abstract The phytotoxicity of clerod-14-ene-3α,4β,13ξ-triol, obtained from Viguiera tucumanensis (Hook. et Arn.) Griseb, was examined in Petri dish bioassays. This clerodane inhibited both germination and root growth of Sorghum halapense and Chenopodium album , and also slightly inhibited Ipomoea purpurea. Crop species also showed inhibitory activity: the growth and germination of Avena sativa was strongly inhibited. Germination of Brassica napus was unaffected. The strongest plant growth inhibitory activity of the clerodane was on C. album , and has been expressed as the p I 50.

Isolation and characterization of anti‐HIV peptides from Dorstenia contrajerva and Treculia obovoidea

Using a high throughput screen based on the interaction of the HIV‐1 gp41 ectodomain with the virucidal protein cyanovirin‐N (CV‐N), we isolated two new peptides which inhibited the binding of CV‐N to gp41 and which subsequently showed anti‐HIV activity in a whole cell assay. A 5‐kDa (contrajervin) and 10 kDa (treculavirin) peptide were isolated from Dorstenia contrajerva and Treculia obovoidea, respectively. Treculavirin was composed of two subunits, each containing 50 amino acid residues, which are covalently linked by at least one disulfide bond between the subunits. Both peptides were shown to bind to gp41 and gp120 and to inhibit the cytopathic effects of HIV‐1RF infection in a human T‐lymphoblastoid cell line (CEM‐SS).

Terpenoid constituents of Viguiera tucumanensis

Abstract Two varieties of Viguiera tucumanensis , collected in two different geographical regions of Argentina, were shown to have a very close chemical constitution. They all gave the new diterpene clerod-14-ene-3α,4β,13ζ-triol. The taxonomic implications are discussed briefly.

Antifeedant activity of metabolites from Viguiera tucumanensis.

Several terpenoids and clerod-14-ene-3 , 4 ,13 -triol ( 1 ), the main compound of V. tucumanensis , were isolated and bioassayed. The clerodane 1 showed higher antifeedant activity than other related compounds. Structure-activity relationships are also discussed.