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Solanidine, leptinidine, and acetylleptinidine from Solanum chacoense Bitter were structurally characterized by high-resolution MS and high-field 1H-NMR and 13C-NMR. 1H-NMR and 13C-NMR chemical shifts were assigned for solanidine and acetylleptinidine using DEPT, HMBC, and HMQC. Complete carbon chemical shift assignments are presented for all three alkaloids. The orientation of the C-23 acetoxyl group of acetylleptinidine was determined to be axial. Keywords: NMR-MS spectroscopy; solanidine; leptinidine; acetylleptinidine

Chromatographic procedures were utilized to isolate and purify components of tobacco cuticular extracts and leaf surface chemicals.In vitro microbial bioassays determined the influence of these leaf surface compounds on germination and germ tube morphology ofP. tabacina sporangia, the tobacco blue mold pathogen, and to a lesser extentAlternaria alternata, the tobacco brown spot pathogen. Exposure to 10 μg/cm(2) of α- and β-duvatrienemonols, sucrose esters, or hydrocarbons did not inhibit germination, whereas germination was significantly decreased bycis-abienol.cis-Abienol did not inhibit sporangial germination when combined with sucrose esters or hydrocarbons at a combined 10 μg/cm(2). Germination of sporangia was completely inhibited by α- and β-duvatrienediols. In contrast to a previous report, α-DVT-diol was more inhibitory than the β isomer. Toxic effects of the DVT-diols were not altered by pH. Diluting the DVT-diols to less than 0.1 μg/cm(2) resulted in a small but significant stimulation of germination. Previously, the DVT-diols had been identified only as inhibitory toP. tabacina. None of the leaf surface chemicals affected germination ofA. alternata conidia.