Bridelia micrantha, commonly known as coastal golden leaf, is a member of the family Phyllanthaceae. In preliminary studies nine fractions, named F1 - F9, were obtained by fractionating the crude methanol extract of t...Bridelia micrantha, commonly known as coastal golden leaf, is a member of the family Phyllanthaceae. In preliminary studies nine fractions, named F1 - F9, were obtained by fractionating the crude methanol extract of the stem bark of Bridelia micrantha using column chromatographic techniques. The fraction F6 was the most active when tested for antibacterial activity. Thus, toxicity of this fraction was investigated for further use. The present study evaluated the acute and sub-chronic toxicity of the crude methanolic bark extract of Bridelia micrantha and its fraction. The acute toxicity was carried out according to the experimental protocol of Organization for Economic Co-operation and Development (OECD). The plant extract or the fraction F<sub>6</sub> was administered orally to female mice at a single dose of 2000 mg/kg and the animals were observed for any behavioral changes or mortality for 14 days. In the sub-chronic toxicity study, the extract and fraction were administered orally at 200, 400 and 800 mg/kg bw/day for 28 days to healthy Wistar rats. The general behavior and body weight of the rats were recorded daily. At the end of the experimental period, hematological and biochemical analyses, changes in vital organ weight (liver, lung, heart, spleen and kidney), and histopathological examination of the liver and kidney were performed. No mortality or adverse effects were noted at the 2000 mg/kg dose during the oral acute toxicity test. In the sub-chronic study, the crude methanolic bark extract of Bridelia micrantha and the fraction F<sub>6</sub> induced no mortality or treatment-related adverse effects on body weight, general behavior, relative organ weights, hematological and biochemical parameters. Histopathological examination of the liver and kidney showed normal architecture suggesting no morphological alterations. In conclusion, the oral administration of the crude methanolic bark extract of Bridelia micrantha and the fraction F<sub>6</sub> for 28 days at a dosage of up to 800 mg/kg did not induce toxicological damage in rats. From acute toxicity study, the median lethal dose (LD<sub>50</sub>) of the crude methanolic bark extract of Bridelia micrantha and the fraction F<sub>6</sub> was estimated to be more than 2000 mg/kg.展开更多
Glucose isomerase(GI)is an enzyme with high potential applications.Characterization of GI producing bacteria with interesting properties from an industrial point of view is essential.Bacillus sp.,Paenarthrobacter sp.,...Glucose isomerase(GI)is an enzyme with high potential applications.Characterization of GI producing bacteria with interesting properties from an industrial point of view is essential.Bacillus sp.,Paenarthrobacter sp.,Chryseobacterium sp.,Hymenobacter sp.,Mycobacterium sp.,and Stenotrophomonas sp.were isolated from soil samples.Optimization of enzyme production yield was investigated in various fermentation conditions using response surface methodology.All isolates exhibited maximum GI activity at 40℃,pH 6–8 after 4 days of incubation.A mixture of peptone/yeast extract or tryptone/peptone enhanced higher enzyme production.The same trend was observed in fermentation medium containing 1%xylose or 2%–2.5%wheat straw.This study advanced the knowledge of these bacterial isolates in promoting wheat straw as feedstock for the bio-based industry.展开更多
High fructose corn syrup has been industrially produced by converting glucose to fructose by glucose isomerases,tetrameric metalloenzymes widely used in industrial biocatalysis.Advances in enzyme engineering and comme...High fructose corn syrup has been industrially produced by converting glucose to fructose by glucose isomerases,tetrameric metalloenzymes widely used in industrial biocatalysis.Advances in enzyme engineering and commercial production of glucose isomerase have paved the way to explore more efficient variants of these enzymes.The 5-hydroxymethylfurfural can be produced from high fructose corn syrup catalytic dehydration,and it can be further converted into various furanic compounds chemically or biologically for various industrial applications as a promising platform chemical.Although the chemical conversion of 5-hydroxymethylfurfural into furanic compounds has been extensively investigated in recent years,bioconversion has shown promise for its mild conditions due to the harsh chemical reaction conditions.This review discusses pro-tein engineering potential for improving glucose isomerase production and recent advancements in bioconversion of 5-hydroxymethylfurfural into value-added furanic derivatives.It suggests bi-ological strategies for the industrial transformation of 5-hydroxymethylfurfural.展开更多
文摘Bridelia micrantha, commonly known as coastal golden leaf, is a member of the family Phyllanthaceae. In preliminary studies nine fractions, named F1 - F9, were obtained by fractionating the crude methanol extract of the stem bark of Bridelia micrantha using column chromatographic techniques. The fraction F6 was the most active when tested for antibacterial activity. Thus, toxicity of this fraction was investigated for further use. The present study evaluated the acute and sub-chronic toxicity of the crude methanolic bark extract of Bridelia micrantha and its fraction. The acute toxicity was carried out according to the experimental protocol of Organization for Economic Co-operation and Development (OECD). The plant extract or the fraction F<sub>6</sub> was administered orally to female mice at a single dose of 2000 mg/kg and the animals were observed for any behavioral changes or mortality for 14 days. In the sub-chronic toxicity study, the extract and fraction were administered orally at 200, 400 and 800 mg/kg bw/day for 28 days to healthy Wistar rats. The general behavior and body weight of the rats were recorded daily. At the end of the experimental period, hematological and biochemical analyses, changes in vital organ weight (liver, lung, heart, spleen and kidney), and histopathological examination of the liver and kidney were performed. No mortality or adverse effects were noted at the 2000 mg/kg dose during the oral acute toxicity test. In the sub-chronic study, the crude methanolic bark extract of Bridelia micrantha and the fraction F<sub>6</sub> induced no mortality or treatment-related adverse effects on body weight, general behavior, relative organ weights, hematological and biochemical parameters. Histopathological examination of the liver and kidney showed normal architecture suggesting no morphological alterations. In conclusion, the oral administration of the crude methanolic bark extract of Bridelia micrantha and the fraction F<sub>6</sub> for 28 days at a dosage of up to 800 mg/kg did not induce toxicological damage in rats. From acute toxicity study, the median lethal dose (LD<sub>50</sub>) of the crude methanolic bark extract of Bridelia micrantha and the fraction F<sub>6</sub> was estimated to be more than 2000 mg/kg.
基金supported by the Natural Science and Engineering Research Council of Canada(NSERC)Discovery Grant(RGPIN-2017-05366)to WQ.
文摘Glucose isomerase(GI)is an enzyme with high potential applications.Characterization of GI producing bacteria with interesting properties from an industrial point of view is essential.Bacillus sp.,Paenarthrobacter sp.,Chryseobacterium sp.,Hymenobacter sp.,Mycobacterium sp.,and Stenotrophomonas sp.were isolated from soil samples.Optimization of enzyme production yield was investigated in various fermentation conditions using response surface methodology.All isolates exhibited maximum GI activity at 40℃,pH 6–8 after 4 days of incubation.A mixture of peptone/yeast extract or tryptone/peptone enhanced higher enzyme production.The same trend was observed in fermentation medium containing 1%xylose or 2%–2.5%wheat straw.This study advanced the knowledge of these bacterial isolates in promoting wheat straw as feedstock for the bio-based industry.
基金supported by the Natural Sciences and Engineering Research Council of Canada(Grant number RGPIN-2017-05366)to WQ.
文摘High fructose corn syrup has been industrially produced by converting glucose to fructose by glucose isomerases,tetrameric metalloenzymes widely used in industrial biocatalysis.Advances in enzyme engineering and commercial production of glucose isomerase have paved the way to explore more efficient variants of these enzymes.The 5-hydroxymethylfurfural can be produced from high fructose corn syrup catalytic dehydration,and it can be further converted into various furanic compounds chemically or biologically for various industrial applications as a promising platform chemical.Although the chemical conversion of 5-hydroxymethylfurfural into furanic compounds has been extensively investigated in recent years,bioconversion has shown promise for its mild conditions due to the harsh chemical reaction conditions.This review discusses pro-tein engineering potential for improving glucose isomerase production and recent advancements in bioconversion of 5-hydroxymethylfurfural into value-added furanic derivatives.It suggests bi-ological strategies for the industrial transformation of 5-hydroxymethylfurfural.
