17-Norkauran-16-one, 18-hydroxy-, (4α)-(±)-

The rosane diterpenoids hugorosenone [3beta-hydroxyrosa-1(10),15-dien-2-one], 18-hydroxyhugorosenone and 18-hydroxy-3-deoxyhugorosenone, and 12-hydroxy-13-methylpodocarpa-8,11,13-trien-3-one were isolated as antifungal constituents of H. castaneifolia Engl. root bark, together with the previously reported di-podocarpanoids hugonone A and hugonone B that were weakly active, and 1(10),15-rosadiene-2beta,3beta-diol (hugorosenol), 4alpha-methoxyhimachal-10-en-5beta-ol (hugonianene B) and 2-hydroxyhenpentacont-2-enal, and the known compounds tetracosyl-(E)-ferrulate and caryophyllene oxide, all of which were inactive. Hugorosenone also exhibited activity against Anopheles gambiae mosquito larvae. Structural determination was achieved based on spectroscopic data.

Two new norditerpenoid acids of the labdane-type (norgrindelic acids), 4,5-dehydro-6-oxo-18-norgrindelic acid (1) and 4beta-hydroxy-6-oxo-19-norgrindelic acid (2), as well as a new grindelic acid derivative, 18-hydroxy-6-oxogrindelic acid (3), were isolated from the aerial parts of Grindelia nana. In addition, the known compounds, 6-oxogrindelic acid, grindelic acid, methyl grindeloate, 7alpha,8alpha-epoxygrindelic acid, and 4alpha-carboxygrindelic acid were also isolated. The structures of the new compounds were characterized on the basis of spectroscopic analysis.

Two new norditerpenoids, 4beta-hydroxy-19-normanoyl oxide (1) and 4alpha-hydroxy-18-normanoyl oxide (2), the new 18-O-alpha-l-arabinopyranosylmanoyl oxide (3a), and the known diterpenoids jhanol (4) and 18-hydroxy-13-epi-manoyl oxide (5) were isolated, together with other common plant constituents from an Argentine collection of Grindelia scorzonerifolia. The structures of the new compounds were established by extensive 1D and 2D NMR techniques and chemical transformations. Structural features of compounds 2 and 4 were verified by X-ray crystallographic analyses. The insecticidal effect of compound 3a was evaluated against the polyphagous pest Spodoptera frugiperda. Pupal and adult malformations leading to death occurred when 3a was incorporated in a larval diet at a concentration of 100 ppm.