In this study, ultrasonic circulating extraction (UCE) technique was firstly and successfully applied for extraction of samara oil from Acer saccharum. The extraction kinetics were fitted and described, and the extraction mechanism was discussed. Through comparison, n-hexane was selected as the extraction solvent, the influence of solvent type on the responses was detailedly interpreted based on the influence of their properties on the occurrence and intensity of cavitation. Seven parameters potentially influencing the extraction yield of samara oil and content of nervonic acid, including ultrasound irradiation time, ultrasound irradiation power, ultrasound temperature, liquid-solid ratio, soaking time, particle size and stirring rate, were screened through Plackett-Burman design to determine the significant variables. Then, three parameters performed statistically significant, including liquid-solid ratio, ultrasound irradiation time and ultrasound irradiation power, were further optimized using Box-Behnken design to predict optimum extraction conditions. Satisfactory yield of samara oil (11.72±0.38%) and content of nervonic acid (5.28±0.18%) were achieved using the optimal conditions. 1% proportion of ethanol in extraction solvent, 120°C of drying temperature and 6.4% moisture were selected and applied for effective extraction. There were no distinct differences in the physicochemical properties of samara oil obtained by UCE and Soxhlet extraction, and the samara oil obtained by UCE exhibited better antioxidant activities. Therefore, UCE method has enormous potential for efficient extraction of edible oil with high quality from plant materials.

Proanthocyanidins were separated for the first time from Cinnamomum longepaniculatum leaves. An experiment-based extraction strategy was used to research the efficiency of an ultrasound-assisted method for proanthocyanidins extraction. The Plackett-Burman design results revealed that the ultrasonication time, ultrasonic power and liquid/solid ratio were the most significant parameters among the six variables in the extraction process. Upon further optimization of the Box-Behnken design, the optimal conditions were obtained as follows: extraction temperature, 100°C; ethanol concentration, 70%; pH 5; ultrasonication power, 660 W; ultrasonication time, 44 min; liquid/solid ratio, 20 mL/g. Under the obtained conditions, the extraction yield of the proanthocyanidins using the ultrasonic-assisted method was 7.88 ± 0.21 mg/g, which is higher than that obtained using traditional methods. The phloroglucinolysis products of the proanthocyanidins, including the terminal units and derivatives from the extension units, were tentatively identified using a liquid chromatography with tandem mass spectrometry analysis. Cinnamomum longepaniculatum proanthocyanidins have promising antioxidant and anti-nutritional properties. In summary, an ultrasound-assisted method in combination with a response surface experimental design is an efficient methodology for the sufficient isolation of proanthocyanidins from Cinnamomum longepaniculatum leaves, and this method could be used for the separation of other bioactive compounds.

A novel actinomycete, designated strain KLBMP 1256T, was isolated from a surface-sterilized stem of the oil-seed plant Jatropha curcas L. collected from Sichuan Province, south-west China, and was characterized to determine its taxonomic position. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the isolate was closely related to members of the genus Nocardia in the family Nocardiaceae, being most closely related to Nocardia callitridis CAP 290T (98.4 % similarity) and Nocardia nova JCM 6044T (97.5 %). Levels of 16S rRNA gene sequence similarity between strain KLBMP 1256T and the type strains of other recognized species of the genus Nocardia were less than 97 %. Chemotaxonomic data supported the affiliation of the new isolate to the genus Nocardia. However, the novel strain could be distinguished from its closest phylogenetic neighbour, N. callitridis CAP 290T, by a range of phenotypic properties. The combination of low DNA–DNA relatedness values and phenotypic differences from N. callitridis CAP 290T indicated that strain KLBMP 1256T represents a novel species of the genus Nocardia, for which the name Nocardia endophytica sp. nov. is proposed. The type strain is KLBMP 1256T ( = KCTC 19777T  = CCTCC AA 2010004T).

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