Postharvest quality maintenance of wax apple and guava fruits by use of a fermented broth of an ε-poly-l-lysine-producing Streptomyces strain.

ε-Poly-l-lysine (ε-PL) is a natural antimicrobial polymer with significant inhibitory activity against a broad spectrum of microorganisms, and nowadays used widely as a preservative in the food industry. In the present study, ε-PL broth was obtained from Streptomyces ahygroscopicus GIM8 fermentation in a nutrient-limited liquid medium. The in vitro antifungal activity of the broth against fruit pathogens Penicillium expansum and Colletotrichum gloeosporioides was investigated, and its usage for postharvest storage of two highly perishable fruits wax apple and guava was evaluated. Results showed that ε-PL concentration in the broth reached 0.61 g/L, and the nutrition level of the broth was low. The antifungal activity of ε-PL broth was comparable to that of the aqueous solution of ε-PL under the same concentration. Immersion with the diluted broth (200 mg/L ε-PL) markedly delayed the decline in the quality of postharvest wax apple and guava fruits during storage, and the decay incidences were also greatly decreased as compared to their respective controls (distilled water immersion). A further investigation demonstrated that the ε-PL broth immersion induced an increase in the activity of defense-related enzymes peroxidase and polyphenol oxidase in the two fruits during storage. The present study proved that the fermentation broth of ε-PL could be used as a promising alternative to high purity ε-PL and synthetic fungicides for preserving fruits at postharvest stage.

Angiogenesis-Inhibitory Piperidine Alkaloids from the Leaves of Microcos paniculata.

Eight new 2,6-disubstituted piperidin-3-ol alkaloids (1-8), featuring a C10 unsaturated alkyl side chain, together with three previously reported analogues (9-11) were isolated from the leaves of medicinal plant Microcos paniculata. Their structures and absolute configurations were elucidated unambiguously by means of 1D and 2D NMR spectroscopic data analysis, modified Mosher's method, Snatzke's method, and quantum chemical electronic circular dichroism (ECD) calculations, as well as single-crystal X-ray crystallography. The isolates were evaluated for their antiangiogenic effects on human umbilical vein endothelial cells (HUVECs). Compound 2 displayed an inhibitory effect on tube formation of HUVECs in a concentration-dependent manner.

[Identification of herbal tea ingredient Plumeria rubra and its adulterants using DNA barcoding].

ITS2 sequence was used as a barcode to identify herbal tea ingredient Plumeria rubra and its adulterants. Genomic DNAs from forty eight samples were extracted, the ITS2 sequences were amplified and sequenced bi-direstionlly, and then assembled and obtained using CodonCode Aligner. The sequences were aligned using ClustalW, the genetic distances were computed by kimura 2-parameter (K2P) model and the Neighbor-joining (NJ) phylogenetic trees were constructed using MEGA5.0. Results showed that the length of ITS2 sequence of P. rubra were 244 bp. The intra-specific genetic distances (0-0. 016 6) were much smaller than inter-specific ones between P. rubra and its adulterants(0.320 8-0.650 4). The NJ tree indicated that P. rubra and its adulterants could be distinguished clearly. Therefore, Using ITS2 barcode can accurately andeffectively distinguish herbal tea ingredient P. rubra from its adulterants, which providesa new molecular method to identify P. rubra and ensure its safety in use.