Mud crab Scylla sp. is a common sea crab species in Vietnam as well as in Asia Pacific. Today, mud crabs are raised on a large scale to be harvested at the soft molting stage because of the high economic value of the finished shell crabs. At present, the processing of soft shell crabs is limited to whole packaging and exporting. However, 30% of soft-shelled crabs in processing often lose their feet and claws, which reduce production costs. Therefore, it is necessary to study the technology of processing soft-shell crabs to improve the value of soft-shelled crab products. Recently, the application of enzymes in processing has brought many benefits such as being environmentally friendly and creating many bioactive substances. In this journal, we built the procedure to determine amino acid content in the processing of Scylla sp. to ensure the quality of products obtained after processing. This procedure based on HPLC using a fluorescence reader. The results showed that the amino acid content after hydrolysis process by enzyme technology reached 65.58% dry weight and contains many valuable amino acids such as lysine, leucine, valine, methionine, histidine.

Helicobacter pylori is one of the most common infectious bacteria in the world that causes gastric diseases leading to cancer. The increase of multiple antibiotic resistance rates of H. pylori have been reported worldwide. Thus, development of novel drugs is urgently required. Piper betle has many therapeutic values in traditional medicine. In this study, therefore, we investigated antibacterial activity of P. betle extracts and their fractions against a H. pylori strain isolated in Vietnam. The agar disk diffusion assay showed inhibition zone of ethyl acetate extract and methanol extract from P. betle leaf that of were 46 mm and 32 mm in diameter, respectively. After fractionation of the ethyl acetate extract through silica gel column chromatography, two peaks, PD2 and PD3, out of 12 fractions showed the strongest antibacterial activity. PD2 was sub-fractionated further by re-chromatography on the silica gel column, and subfraction TK12 gave best resolution on LC-MS analysis. Finally, 4 potential compounds, quercetrin, calodenin B, vitexin and plicatipyrone, were identified in TK12 fraction.

No abstract

Nhận ngày 16 tháng 8 năm 2017Chỉnh sửa ngày 20 tháng 9 năm 2017; Chấp nhận đăng ngày 10 tháng 10 năm 2017Tóm tắt: Vi khuẩn Helicobacter pylori được xác định là nguyên nhân chính gây ra các bệnh đường tiêu hóa với khả năng kháng thuốc điều trị đang ngày càng tăng lên. Đề tài nghiên cứu tinh sạch peptide deformylase, enzyme có vai trò xúc tác cho phản ứng loại bỏ nhóm formyl đầu N của chuỗi peptide mới hình thành trong vi khuẩn như một đích tác dụng mới cho việc sàng lọc, phát triển thuốc diệt Helicobacter pylori. Peptide deformylase tái tổ hợp từ Helicobacter pylori biểu hiện ở E. coli BL21-RIL có kích thước xấp xỉ 24,5 kDa được tách chiết thành công với hiệu suất đạt 37,2% và độ tinh sạch tăng lên 13 lần. Hoạt tính cắt nhóm formyl của HpPDF khá cao với K m là 137,16 µM và k cat /K m là 173,42 M -1 s -1 và hoạt độ riêng đạt 145,3 U/mg. Từ khóa: Peptide deformylase, Helicobacter pylori, tái tổ hợp, hoạt tính, kháng thuốc.Abstract: Helicobacter pylori is the major reason causesing gastrointestinal diseases and is characterized with the rapidly increase of multi drug resistance. In this project, we focused on studying peptide deformylase catalyzing for the crucial N-formyl cleavage from N-formyl methionyl at the beginning of new peptide chains in prokaryotes as an alternative target for screening potential anti-H. pylori compounds. The 24.5 kDa recombinant HpPDF expressed in E. coli BL21-RIL was successfully purified with a 13-fold increase in purity and 37.2% yield. HpPDF formyl removing pecific activity was determined at 145.3 U/mg with K m of 137.16 µM and k cat /K m ratio of 173.42 M -1 s -1 .

No abstract