Phenolic acids are the main active substances that contribute to the antioxidant activity of Echinacea purpurea (L.) Moench, Asteraceae. However, the effect of chromosome doubling and developmental growth stage on the phenolic acid accumulation and the antioxidant capabilities of E. purpurea has remained unclear. Our systematic studies indicate that the dry weight of tetraploid plants is significantly higher than that of diploid plants, leading to higher yields of cichoric acid, caffeic acid, chlorogenic acid, caftaric acid, and 1,5-dicaffeoyl quinic acid compared with diploid plants, at different growth stages. Cichoric acid and caftaric acid are the predominant compounds in diploid individuals. The period with the higher yields of cichoric acid and caftaric acid are coincided with that of total phenolic acids in four investigated organs (root, leaf, stem, and flower), which mostly observed during the flowering period (August). Furthermore, antioxidant activities in four different organs of tetraploid individuals were higher than those in diploid plants, at each growth stage. The changes in the antioxidant activity in different organs (flower, root, leaf, and stem) of diploid individuals were significantly and positively correlated with the trends in the content changes of total phenolic acids throughout different growth stages. Blooming time should be chosen as the best harvest time for both diploid and tetraploid plants, and the flowers and leaves may be used as raw materials for the extraction of total phenolic acids and development of antioxidant supplements to stimulate the immune system.
The high toxicity, long-lasting residues, and resistance to chemical pesticides and baits used in the control of red imported fire ants could possibly harm human health and ecological balance. Natural compounds would be an excellent source of pesticides because of their good repellency and insecticidal properties. In this study, the fumigation method was used to study the insecticidal effects of essential oils from the bark and leaves of Cinnamomum loureirii Nees on red imported fire ants at different concentrations and fumigation time. The fumigation time with C. loureirii essential oils was positively correlated with the knockdown ability and mortality in red imported fire ants and was negatively correlated with grasping ability. The insecticidal activity of the essential oil extracted from C. loureirii leaves was significantly higher than that of the essential oils extracted from bark at effective concentrations. Cinnamyl acetate, an abundant component in leaf essential oil, plays an important role in improving the insecticidal activity of trans-cinnamaldehyde. This study provides a theoretical basis for the development and utilization of cinnamon leaf oil as a new environmentally friendly insecticide resource for the control of red imported fire ants.
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