Antioxidant Activities of Essential Oils and Their Major Components in Scavenging Free Radicals, Inhibiting Lipid Oxidation and Reducing Cellular Oxidative Stress.

Antioxidant activities of five essential oils (cinnamon, thyme, clove, lavender and peppermint oils) and their major components (eugenol, thymol, linalool, and menthol) were evaluated on scavenging DPPH (2,2-diphenyl-1 picrylhydrazyl) free radicals, inhibiting polyunsaturated fatty acid oxidation in fish oil emulsion (FOE), and reducing oxidative stress in human red blood cells (RBC). The essential oils from cinnamon, thyme, clove and their main components, eugenol and thymol, exhibited the highest antioxidant activity in the FOE and RBC systems. It was found that the antioxidant activity of essential oils was positively correlated to the content of eugenol and thymol, while lavender and peppermint oils and their main components, linalool and menthol, had very low antioxidant activity. Compared with scavenging DPPH free radical activity, the antioxidant activity in FOE and RBC systems could better reflect the actual antioxidant potential of essential oil in preventing lipid oxidation and reducing oxidative stress in biological system.

Microscopic Observations on Form and Structure of the Worm Enchytraeus buchholzi (Clitellata: Enchytraeidae).

BACKGROUND: The worm Enchytraeus buchholzi is a new record species for Shaanxi, China, and a key pest on American ginseng Panax quinquefolium. To distinguish the species, the authors prepared its whole mounts and paraffin-embedded sections, and microscopically observed, photographed and measured. Besides, we conducted an experimental study on its DNA barcode.  RESULTS: Cells, tissues and organs related to nervous, digestive, circulatory, excretory and reproductive systems were found, photomicrographed and described, including: prostomium, peristomium, segments, clitellum, pygidium, lateral and ventral chaetae; brain, cranial nerves, sensory papillae, ventral nerve cord; pharyngeal pad and glands, retractor muscles and muscular bundles, peptonephridia, esophagus, intestine; dorsal, lateral, ventral and intestinal parietal vessels, coelomocytes, coelomic cavity; nephridia, chloragogen cells; ovaries, groups of germ cells with developing oocytes, mature eggs, spermathecae; testes, seminal vesicles, sperm funnels, penial bulbs. Their shapes and sizes were given, and functions discussed briefly. The visual effect of staining specimens with hematoxylin plus eosin ranked the first, and that with acetocarmine the second.  CONCLUSIONS: The supplementary and objective descriptions, with the microphotographs as forceful pieces of evidence, have expanded biological knowledge in aspects of the form, structure and function of the worm, which is helpful for professionals to recognize and understand this species and provide a solid basis for its integrated pest management.

Collagens made from giant salamander (Andrias davidianus) skin and their odorants.

Two collagens were made from giant salamander (Andrias davidianus) skin by using acid and pepsin extraction methods. The yields of acid-soluble and pepsin-soluble collagens were 26.9 and 58.7%, respectively. The results of spectrum, electrophoresis and amino acid analysis showed that they were type 1 collagen with two α and one ß peptides and high imino acid content. They had low solubility at a pH above 6 or salt concentration over 5%. The pepsin-soluble collagen had a better emulsion activity index. The odorants in raw skin and collagens were identified and evaluated using gas-chromatography mass-spectrometer and olfactometry methods and sensory analysis. The fishy and fatty off-odors in skin were not perceivable in the collagens. Sour, ammonia-like, and acrid off-odors were found in the collagens due to acid and enzymatic hydrolysis and protein degradation. The off-odor intensity of pepsin-soluble collagen was low. It could be considered a good and safe collagen material.

Aroma characterization of Hanzhong black tea (Camellia sinensis) using solid phase extraction coupled with gas chromatography-mass spectrometry and olfactometry and sensory analysis.

The unique aroma of the Hanzhong black tea is due to the special location of the harvesting place and specific manufacturing processes. In this study, a solid phase extraction method (SPE) as sample preparation tool was combined with gas chromatography (GC) as separation technique and several detection systems such as mass spectrometry (MS), flame ionization (FID) and olfactometry (O), which, together with sensorial analysis were used to characterize aroma compounds in Hanzhong black tea infusion. Seventy three aroma compounds were identified and quantified in the tea infusion by the GC-MS and GC-FID methods, respectively. Among them, odor perceptions of 24 compounds were characterized by the GC-O analysis. It was found that linalool oxide I, II and III, E,E-2,4-nonadienal, 4,5-dimethyl-3-hydroxy-2,5-dihydrofuran-2-one, 1-octen-3-one, E,Z-2,6-nonadienal, bis(2-methyl-3-furyl) disulfide had higher odor activity value in the tea infusion and offered floral, fatty, and caramel, mushroom, cucumber, and cooked beef -like odors, respectively. Overall, floral and mushroom and caramel -like odors significantly dominated in the Hanzhong black tea infusion.

Selectively screen the antibacterial peptide from the hydrolysates of highland barley.

Highland barley is one of the most important industrial crops in Tibetan plateau. Previous research indicated that highland barley has many medical functions. In this work, the antibacterial abilities of highland barley were investigated. The protein solutions hydrolyzed by trypsin for 4 h exhibited the highest antibacterial activity. An antibacterial peptide, barleycin, was screened and purified by magnetic liposome extraction combining with the protein profiles of reversed-phase high-performance liquid chromatography (RP-HPLC). Structure, characterization, and safety evaluation of barleycin were further investigated. Amino acids sequence was determined as Lys-Ile-Ile-Ile-Pro-Pro-Leu-Phe-His by N-sequencing. Circular dichroism spectra indicated the a-helix conformation of barleycin. The activity spectrum included Bacillus subtilis, Staphylcoccus aureus, Listeria innocua and Escherichia coli and the MICs were from 4 to 16 µg/mL. Safety evaluations with cytotoxicity and hemolytic suggested this antibacterial peptide could be considered as safe at MICs. Finally, mode of action of barleycin on sensitive cells was primarily studied. The results suggested the damage of cell membrane.

Effects of high hydrostatic pressure on the growth and beta-carotene production of Rhodotorula glutinis.

The effects of high hydrostatic pressure (HHP) on the biomass and beta-carotene biosynthesis of Rhodotorula glutinis R68 were studied. After treatment with five repeated cycles at 300 MPa for 15 min, the barotolerant mutant PR68 was obtained. After 72 h of culture, the biomass of mutant PR68 was 21.6 g/l, decreased by 8.5% compared to the parental strain R68, but its beta-carotene production reached 19.4 mg/l, increased by 52.8% compared to the parental strain R68. The result of restriction fragment length polymorphism (RFLP) analysis suggested that mutant strain PR68 was likely to change in nucleic acid level, and thus enhanced beta-carotene production in this strain as a result of gene mutation induced by HHP treatment.