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Pyrrolizidine alkaloids (PAs) are feeding deterrents and toxic compounds to generalist herbivores. Among the PAs of Jacobaea vulgaris Gaertn, jacobine and erucifoline are the most effective against insect herbivores as indicated by correlative studies. Because little is known about the effect of jacobine and erucifoline as individual PAs, we isolated these compounds from their respective Jacobaea chemotypes. These PAs and other commercially available senecionine-like PAs, including senecionine, seneciphylline, retrorsine, and senkirkine, were tested as free base and N-oxide forms at a range of 0-70 ppm. Feeding bioassays using live insects are closer to the natural pattern but require relatively large amounts of test compounds. We, therefore, compared the toxicity of PAs using both Spodoptera exigua cell line and larval injection bioassays. Both bioassays led to similar results in the order of PA toxicity, indicating that the cell lines are a valuable tool for a first toxicity screen. Testing individual PAs, jacobine and erucifoline were the most toxic PAs, suggesting their major role in plant defense against generalist herbivores. Senkirkine and seneciphylline were less toxic than jacobine and erucifoline but more toxic than retrorsine. Senecionine was not toxic at the tested concentrations. For all toxic PAs, the free base form was more toxic than the N-oxide form. Our results demonstrate that structural variation of PAs influences their effectiveness in plant defense.

The antioxidant and cytotoxic activities of the chloroform extract of agarwood (Gyrinops versteegii (Gilg.) Corresponding author: a) tririni@ugm.ac.idAbstract. Several factors involve in the synthesis of secondary metabolites in plants, including leaves maturity. The objectives of this study were to compare the antioxidant and antibacterial activities of agarwood Aquilaria malaccensis Lamk. leaves at different stages of maturity as well as to identify the group of compounds responsible to the corresponding activities. Young and old leaves of agarwood were used. Leaves were powdery dried and extracted using three different polarity solvents including chloroform, methanol and water using Soxhlet apparatus. The potential extract was fractionated using Vacuum Liquid Chromatography (VLC). Antioxidant activity was analysed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) while antibacterial activity was evaluated using paper disc diffusion assay. Thin Layer Chromatography (TLC) followed by spraying with specific reagents was applied to identify groups of bioactive compounds in the potential fraction. The results showed that the methanol extract of the old leaves was the most potential extract with an IC50 value of 19.62 ± 1.49 μg/ml and the combined fraction of 1:3 chloroform: methanol and 100% methanol showed the highest antioxidant activity with IC50 17.39 ± 1.43 μg/ml. The chloroform extract of old leaves showed the highest antibacterial activity on S. aureus and E. coli with a diameter of inhibition zone of 10.83 mm and 9.92 mm respectively at concentration extract of 300 mg/ml. While the most potential fraction as antibacterial on S. aureus and E. coli was chloroform fraction that showed 3 times higher activity than the crude extract. The fraction with highest antioxidant activity contained phenolic and flavonoid, while the potential antibacterial fraction contained alkaloid and terpenoid. Old agarwood of A. malaccensis leaves showed higher potency as an antioxidant and antibacterial than the young leaves.

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Background Productivity and quality of crops can be increased through polyploidy plants induced by colchicine. The use of colchicine has never been applied to Katokkon pepper, a local red pepper variety from North Toraja Indonesia. This pepper is characterized by its unique shape like the small-bell pod type of paprika and its strong spicy taste. Therefore, this study aimed to determine the effects of colchicine treatment on the ploidy level and morphological characters of Katokkon pepper. Results Flow cytometer analysis showed that all colchicine concentration treatments ranging from 0.025 to 0.1% with 24 h immersion time generated two plant groups based on their ploidy level; 50% of the total treatment plants was diploid while the rest plants were mixoploid. All colchicine treatment plants were significantly different in their width of stomata guard cells from the control plant. The effect of colchicine was also significantly on the plant height, thickness of fruit flesh, and the number of fruits per plant. Conclusions The results of this study showed that colchicine treatment had a significant effect on the ploidy level and several morphological characters of the Katokkon pepper. The colchicine treatment increased the number of fruits per plant and thicker flesh of fruits but reduced the size and weight of Katokkon pepper. Our findings provide essential information to obtain tetraploid Katokkon plants through colchicine treatment in further research. This study benefits as a preliminary step for increasing the productivity and quality of the local red peppers in Indonesia.

Metabolomics allows the identification of biochemical markers that have important roles in plant resistance to pests and diseases by which breeders can select plants based on differences in these compounds. This study examines the range of compounds associated with plant defense against nematodes. Resistant tomato genotypes, GM2 and F1 (GM2 × Hawai 7996), and susceptible genotypes, Gondol Putih and Gondol Hijau, were used in this study. Peroxidase activity was measured colorimetrically using a spectrophotometer. 1H-NMR (nuclear magnetic resonance) spectroscopy combined with orthogonal projections to latent structures discriminant analysis was used to analyze the metabolites involved in the tomato-nematode interactions. Identified signals were semi-quantitatively calculated by scaling the intensity of the 1H-NMR to the signals of an internal standard (trimethyl silyl-3-propionic acid) at 0.00 ppm. Resistant plants showed a higher peroxidase activity than susceptible plants. Chemical compounds that differentiated between susceptible and resistant plants were glucose and caffeic acid. Resistant tomatoes were observed to have seven times higher level of glucose than susceptible plants. Glucose is the primary metabolite that acts in the signaling pathways in plant defense mechanisms. Caffeic acid is one of the phenolic compounds alleged to have a negative effect on the nematode.

There is a correlation between the metabolites specifically associated to the expression of different flower colours and the metabolite profile of other plant organs and it is therefore possible to predict the flower colours by detecting specific metabolites in leaves, stems or roots. This may have interesting application in the plant breeding industry.