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Nine neo-clerodane diterpenoids and a mixture of C-16 epimers - scutegalerins C and D, isolated from Scutellaria galericulata (Labiatae), were tested for insect antifeedant activity against Leptinotarsa decemlineata (Say) larvae in choice feeding assays. Treatment of potato leaf disks with small amounts of the natural products (1000, 100, 10 ppm) demonstrated a significant antifeedant activity. Results were compared with one of the used in feeding assays compounds - 14,15-dihydrojodrellin T, which is known as a very powerful feeding suppressor and deterrent against insect pests. Activity was established by calculating the feeding ratio (FR) between the consumed areas of treated disks (CTD) and control disks (CCD). To obtain comparison results was established a FR50 determined as the FR at a CCD of 50% was established. Some of the compounds exhibited activity at dose 10 ppm (0.33 μg/cm2). The purpose of this study was to define the structural features of the clerodanes and to determine their antifeedant activity. [ABSTRACT FROM AUTHOR]

A study of the influence of different extracts from Mentha aquatica L. and Mentha longifolia L. on the activity of glycosyltransferase complex from Leuconstoc nesenteroides URE 13 and dextransucrase from Leuconostoc mesenteroides Lm 28 was carried out. The extracts from two plant species showed an inhibitory effect on studied glycosyltransferases at minimal concentration of the total extract 1.87 mg/ml in the reaction mixtures. At this concentration the enzyme complex from URE 13 strain lost about 18% (M. longifolia L.extract) and 12% (M. aquatica L.extract). For dextransucrase from Lm 28 strain a higher inhibition varying from 22% (M. longifolia extract) to 30% (M. aquatic extract) was detected. When the concentration of the extracts was raised to 9.35 mg/ml, the inhibitory effect on the enzyme complex from URE 13 and dextransucrase from Lm 28 strain increase. At this concentration of the extracts a higher percent of inhibition was detected for the enzyme from Lm 28 strain - 100% for the extract from both M. longifolia L and 98% for this from M. aquatica L. For the enzyme from L. mesenteroides URE 13 strain, at concentration 9.35 mg/ml was determined 97% inhibition for both plant extracts. The inhibitory effect of both extracts on the studied enzymes was compared with equivalent concentrations of essential oil from M. piperita L. where an inhibitory effect ranging from 63% (URE 13 enzyme complex) to 76% (Lm 28 dextransucrase) was observed. The effect of the extracts from both Mentha sp. on transferase to hydrolase activity ratio was also studied and showed predominance of transferase activity with more than 90% at 24 h from the start of the reactions. [ABSTRACT FROM AUTHOR]