α-amylase detection methods and applications / 生物工程学报

α-amylase is an endonucleoside hydrolase that hydrolyzes the α-1, 4-glycosidic bonds inside polysaccharides, such as starch, to generate oligosaccharides, dextrins, maltotriose, maltose and a small amount of glucose. Due to the importance of α-amylase in food industry, human health monitoring and pharmaceuticals, detection of its activity is widely required in the breeding of α-amylase producing strains, in vitro diagnosis, development of diabetes drugs, and the control of food quality. In recent years, many new α-amylase detection methods have been developed with improved speed and sensitivity. This review summarized recent processes in the development and applications of new α-amylase detection methods. The major principle of these detection methods were introduced, and their advantages and disadvantages were compared to facilitate future development and applications of α-amylase detection methods.

Chemical characterization, antioxidant activity, -amylase and acetylcholinesterase inhibitory potential of Angelica pancicii Vandas ex Velen / Caracterización química, actividad antioxidante, potencial inhibidor de -amilasa y acetilcolinesterasa de Angelica pancicii Vandas ex Velen

Abstract: Comparative study GC - FID /M S of essential oils of fruits, leaves and roots of the endemic plant Angelica pancicii Vandas ex Velen. revealed a significant difference in their chemical composition. The enantiomeric purity of the main component in the fruit oil (+) - ß - phellandrene was a lso confirmed. In addition, imperatorin, isoimperatorin, oxypeucedanin, oxypeucedanin hydrate, angeloylpangelin and umbelliprenin were isolated from the fruit hexane extract. The content of these coumarins in the hexane extracts from different plant parts was further determined by HPLC. The essential oils and hexane extracts were assessed for their antioxidant potential and inhibitory effect towards  - amylase and acetylcholinesterase enzymes. The fruit and leaf essential oils (> 80%) as well as the fruit he xane extract (> 62%) significantly inhibited acetylcholinesterase enzyme. Distinguish free radical scavenging properties were detected for the leaf (Inh. 95.0 ± 2.2 %) and the root (Inh. 66.0 ± 2.4 %) extracts.

Resumen: Estudio comparativo GC - FID / MS de aceites esenciales de frutas, hojas y raíces de la planta endémica Angelica pancicii Vandas ex Velen revelaron una dife rencia significativa en su composición química. También se confirmó la pureza enantiomérica del componente principal del aceite de fruta (+) - ß - felandreno. Además, se aislaron imperatorina, isoimperatorina, oxipeucedanina, hidrato de oxipeucedanina, angeloi lpangelina y umbeliprenina del extracto de hexano del fruto. El contenido de estas cumarinas en los extractos de hexano de diferentes partes de la planta se determinó adicionalmente mediante HPLC. Los aceites esenciales y extractos de hexano se evaluaron p or su potencial antioxidante efecto inhibidor de las enzimas -  - amilasa y acetilcolinesterasa. Los aceites esenciales de frutas y hojas (> 80%), así como el extracto de hexano de frutas (> 62%) inhibieron significativamente la enzima acetilcolinesterasa. Se detectaron propiedades de captación de radicales libres diferenciadas para los extractos de hoja (Inh. 95,0 ± 2,2%) y de raíz (Inh. 66,0 ± 2,4%).

Molecular cloning and biochemical characterization of an α-amylase family from Aspergillus niger

Background: α-Amylase is widely used in the starch processing, food and paper industries, hydrolyzing starch, glycogen and other polysaccharides into glucose, maltose and oligosaccharides. An α-amylase gene family from Aspergillus niger CBS513.88 encode eight putative α-amylases. The differences and similarities, biochemical properties and functional diversity among these eight α-amylases remain unknown. Results: The eight genes were cloned and expressed in Pichia pastoris GS115 by shaking-flask fermentation under the induction of methanol. The sequence alignment, biochemical characterizations and product analysis of starch hydrolysis by these α-amylases were investigated. It is found that the eight α-amylases belonged to three different groups with the typical structure of fungal α-amylase. They exhibited maximal activities at 30­40°C except AmyG and were all stable at acidic pH. Ca2+ and EDTA had no effects on the activities of α-amylases except AmyF and AmyH, indicating that the six amylases were Ca2+ independent. Two novel α-amylases of AmyE and AmyF were found. AmyE hydrolyzed starch into maltose, maltotriose and a small amount of glucose, while AmyF hydrolyzed starch into mainly glucose. The excellent physical and chemical properties including high acidic stability, Ca2+-independent and high maltotriose-forming capacity make AmyE suitable in food and sugar syrup industries. Conclusions: This study illustrates that a gene family can encode multiple enzymes members having remarkable differences in biochemical properties. It provides not only new insights into evolution and functional divergence among different members of an α-amylase family, but the development of new enzymes for industrial application.

Evaluation of cytogenotoxicity, antioxidant and hypoglycemiant activities of isolate compounds from Mansoa hirsuta D.C. (Bignoniaceae)

ABSTRACT Mansoa hirsuta (Bignoniaceae) is a native plant from caatinga in Brazilian semiarid. This plant has been locally used as antimicrobial and hypoglycemiant agents, but their action mechanisms and toxicity remain largely unknown. Therefore, we evaluated the composition and antioxidant, cytoprotective and hypoglycemiant effects of raw extract, fractions and compounds from leaves of M. hirsuta. The cytogenotoxic effects of ursolic and oleanolic acids, the main phytotherapic components of this plant, were assessed. The raw extract and fractions presented steroids, saponins, flavonols, flavanonols, flavanones, xanthones, phenols, tannins, anthocyanins, anthocyanidins and flavonoids. The ethyl acetate fraction inhibited efficiently the cascade of lipid peroxidation while the hydroalcoholic fraction was richer in total phenols and more efficient in capturing 2,2-diphenyl-1-picrylhydrazyl (·DPPH) and 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS·+) radicals. The isolated fraction of M. hirsuta also inhibited the α-amylase activity. Cytotoxic effects were absent in both raw extract and fractions while ursolic+oleanolic acids were efficient in protecting cells after exposure to hydrogen peroxide. Moreover, this mixture of acid shad no significant interference on the mitotic index and frequency of nuclear and/or chromosomal abnormalities in Allium cepa test. Therefore, M. hirsuta represents a potential source of phytochemicals against inflammatory and oxidative pathologies, including diabetes.

Production of amylases by Aspergillus tamarii

A strain of Aspergillus tamarii, a filamentous fungus isolated from soil, was able to produce both Ó-amylase and glucoamylase activities in mineral media supplemented with 1(per cent) (w/v) starch or maltose as the carbon source. Static cultivation led to significantly higher yields than those obtained using shaking culture. The production of amylases was tolerant to a wide range of initial culture pH values (from 4 to 10) and temperature (from 25 to 42degree C). Two amylases, once Ó-amylase and one glucoamylase, were separated by ion exchange chromatography. Both partially purified enzymes had optimal activities at pH values between 4.5 and 6.0 and were stable under acid conditions (pH 4.0-7.0). The enzymes exhibited optimal activities at temperatures between 50(degree) and 60(degree) C and wete stable for more than ten hours at 55(degree) C.