Effect of plant phenolic compounds on biofilm formation by Pseudomonas aeruginosa

In the natural environment, bacteria predominantly exist in matrix‐enclosed multicellular communities associated with various surfaces, referred to as biofilms. Bacteria in biofilms are extremely resistant to antibacterial agents thus causing serious problems for antimicrobial therapy. In this study, we showed that different plant phenolic compounds, at concentrations that did not or weakly suppressed bacterial growth, increased the capacity of Pseudomonas aeruginosa PAO1 to form biofilms. Biofilm formation of P. aeruginosa PAO1 was enhanced 3‐ to 7‐fold under the action of vanillin and epicatechin, and 2‐ to 2.5‐fold in the presence of 4‐hydroxybenzoic, gallic, cinnamic, sinapic, ferulic, and chlorogenic acids. At higher concentrations, these compounds displayed an inhibiting effect. Similar experiments carried out for comparison with Agrobacterium tumefaciens C58 showed the same pattern. Vanillin, 4‐hydroxybenzoic, and gallic acids at concentrations within the range of 40 to 400 μg/mL increased the production of N–3‐oxo‐dodecanoyl‐homoserine lactone in P. aeruginosa PAO1 which suggests a possible relationship between stimulation of biofilm formation and Las Quorum Sensing system of this bacterium. Using biosensors to detect N‐acyl‐homoserine lactones (AHL), we demonstrated that the plant phenolics studied did not mimic AHLs.     

区分3种法定基源麻黄的酚类成分HPLC特征图谱中指标成分的确定及4种成分的含量测定

针对麻黄中酚类成分建立HPLC特征图谱,寻找其中指标成分,并对其在草麻黄、中麻黄、木贼麻黄草质茎中的分布及含量规律进行分析。利用HPLC-DAD建立酚类成分特征图谱,采用YMC-Pack ODS-A(4.6 mm×250 mm, 5 μm)色谱柱,以0.01%甲酸水溶液-乙腈为流动相,梯度洗脱,流速1.0 mL·min^-1,柱温40℃,检测波长330, 350 nm。对46批次法定基源麻黄自采样品进行测定,所得图谱可实现基源间有效区分。结合主成分分析、峰面积分布分析,细致探讨图谱中12个主要成分峰对3种法定基源麻黄特征及差异的贡献:其中,10, 11, 12号峰峰面积在木贼麻黄中显著高于另两基源,利用其总峰面积值(木贼麻黄中高于146 mAU),可实现木贼麻黄与另两基源的有效区分;1号峰峰面积在草麻黄、4号峰峰面积在中麻黄中显著高于其他法定基源,分别为两基源麻黄中重要的差异成分峰;8,9号峰为3种基源麻黄中的共有特征成分峰;其余各峰在不同基源麻黄中的分布存在不同程度差异,辅助上述成分,实现3种法定基源麻黄的有效区分。进一步利用上述色谱条件,首次测定了法定基源麻黄中异牡荆素-2"-O-α-L-鼠李糖苷(1)、牡荆素(2)、茶花粉黄酮B(5)、草棉黄素-7-O-β-D-葡萄糖苷(6)4种指标成分的含量,在检测范围内线性良好,平均加样回收率为97.8%~102.5%。所测样品中4种成分的含量范围分别为trace~1.55(1),trace~0.160(2),trace~0.284(5),trace~0.620(6) mg·g^-1,且不同基源麻黄中,各成分含量存在差异。其中,1在草麻黄中质量分数(0.670±0.88) mg·g^-1显著高于另两基源麻黄(除Ei-060630-2-2外低于0.16 mg·g^-1); 6 在木贼麻黄中平均含量水平(0.260±0.039 2) mg·g^-1达草麻黄(0.120±0.270) mg·g^-1与中麻黄(0.136±0.485) mg·g^-1中的2倍,此二成分对法定基源麻黄间区分有重要贡献。所建酚类成分HPLC特征图谱与含量测定方法较为简便、准确,选定指标成分为区分麻黄基源、完善药材质量标准,提供了新的科学依据。     

用QSTR模型预测苯酚类化合物大鼠经口的急性毒性△

对39种苯酚类化合物大鼠经口急性毒性(LD50)的定量结构-毒性效应关系(Quantitative Structure-Toxicity Relation-ships,QSTR)进行了研究。采用HyperChem7.5中MOPAC-AMI量子化学法计算了39种苯酚类化合物的13种量子化学结构参数。其中取22个化合物作为样本集对LD50进行多元逐步回归分析,得到最佳方程,该方程的相关系数R2=0.9749。应用所建立的QSTR模型验证了苯酚类化合物的LD50值。经过17个预测样本对该模型进行验证,结果表明该模型具有很好的预测能力。同时分析了苯酚类化合物的毒性机理。     

Antioxidant properties, total phenols and pollen analysis of propolis samples from Portugal

Pollen analysis, total phenols content and antioxidant activity were studied for the first time in Portuguese propolis samples from Bornes and Fundão regions. Total phenols content was determined by colorimetric assay and their amount was of 329 mg/g of GAE in Bornes sample and 151 mg/g of GAE in Fundão propolis. The antioxidant capacity of propolis extracts was assessed through the scavenging effects on DPPH (2,2-diphenyl-1-picrylhydrazyl) and reducing power of iron (III)/ ferricyanide complex assays. A concentration-dependent antioxidative capacity was verified in DPPH and reducing power assays. Low values of EC₅₀ on DPPH scavenging assay were obtained for Bornes and Fundão propolis (of 6.22 μg/mL and 52.00 μg/mL, respectively). For reducing power the values were 9.00 μg/mL, for Bornes propolis, and 55.00 μg/mL, for Fundão propolis. The high activity of propolis from Bornes could be related with their different pollen composition. The results obtained indicate that Portuguese propolis is an important source of total phenols showing antioxidant properties that could be beneficial for human health.     

HPLC测定不同采收期球花石斛中酚类成分的含量

目的:比较不同采收期球花石斛叶酚类成分(联苄、菲和芴酮类成分)的含量变化,为球花石斛的合理采收及质量评价提供科学依据。方法:采用高效液相色潜法对不同采收期球化石斛中联苄类化合物石斛酚(gigantol)和杓唇石斛素(moscatil-in),菲类化合物 moscatin 及芴酮类化合物 dendroflorin、dengibsin 和 denchrysan A 的含量进行测定。色谱条件:色谱柱为 Beck-man Coulter ODS(250 mm×4.6 mm,5μm);流动相为乙腈和0,1%二氟醋酸水溶液,梯度洗脱[32%A(0～15 min),32%A→65%A(15～45 min),65%A→32%A(45～55 min)],流速:1.0 mL·min~(-1);检测波长280 nm;柱温25℃。结果:石斛酚、杓唇石斛素、moscatin、dendroflorin、dengibsin 和 denchrysan A 在测定的范围内均表现出良好的线性(r>0.9992);方法的回收率在95.8%～102.4%之间(RSD<2.8%)。结论:通过对同一年12个月不同采收期的球花石斛中联苄、菲和芴酮类成分的含量测定,证明方法灵敏,准确可靠,重复性好。总酚类成分的含量在4,5月份和10,11月份相对高于其他月份。     

复方姜附制剂中有效部位干姜的质量控制研究

目的建立中药复方姜附制剂中干姜有效部位的含量测定方法。方法采用UV法和HPLC法。结果UV法线性范围19~39μg/m l,相关系数r=0.999 2,总酚的平均回收率为101.4%,RSD=1.8%(n=6)。HPLC法线性范围0.2~2.0μg,相关系数r=0.999 9,6-姜酚的平均回收率为98.57%,RSD=0.31%(n=6)。结论该法灵敏,简便,准确和重现性好,可作为该制剂的质量控制标准。     

超声辅助大孔树脂技术富集荆芥穗中总黄酮和总酚的工艺研究

目的 通过超声辅助大孔树脂对荆芥穗Schizonepetae Spica水提物中总黄酮和总酚类化合物进行富集并对比处理前后化合物含量及活性变化。方法 从7种不同类型树脂中筛选超声辅助最佳树脂型号,在吸附动力学和吸附热力学研究下,对超声温度、功率、上样质量浓度及解吸溶剂百分比等影响因素进行工艺优化。测定了优化处理前后各成分含量及活性变化。结果 动力学和热力学的研究表明,荆芥穗总黄酮适用于Langmuir模型,且吸附过程为自发吸热熵增,总酚则为自发放热熵减并适用于Freundlich模型,据此不同的吸附机制优化了2类成分同时富集的最佳工艺,在超声辅助AB-8大孔树脂,温度25 ℃、时间2.5 h,功率150 W,上样质量浓度0.1 g/mL,70%乙醇解吸附的过程下,荆芥穗水提物中总黄酮和总酚类化合物含量增加2～3倍,其单体成分的含量及抗氧化和神经氨酸酶抑制活性均显著增加。结论 超声辅助大孔树脂技术为荆芥穗总黄酮和总酚类成分的有效可行富集技术。     

Phenolic composition,antioxidant and anti-acetylcholinesterase activities of the Tunisian Scabiosa arenaria

Abstract

Context: There is a need for the discovery of novel natural antioxidants and acetylcholinesterase inhibitors (AChEIs) that are safe and effective at a global level. This is the first study on antioxidant and anti-acethylcholinesterase activity of Scabiosa arenaria Forssk (Dipsacaceae).

Objective: The antioxidant potential and anti-acetylcholinesterase (AChE) activity of S. arenaria were investigated.

Material and methods: The crude, ethyl acetate (EtOAc), butanol (n-BuOH) and water extracts prepared from flowers, fruits and stems and leaves of S. arenaria were tested to determine their total polyphenol content (TPC), total flavonoid content (TFC), total condensed tannin content (CTC) and their antioxidant activity by using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), reducing power and β-carotene bleaching inhibition activity. Anti-AChE activity was also determined.

Results: EtOAc and n-BuOH fractions of fruits had both the highest (TPC) (269.09?mg gallic acid equivalents/g dry weight). The crude extract of stems and leaves had the highest TFC (10.9?mg quercetin equivalent/g dry weight). The n-BuOH fraction of stems and leaves had the highest CTC (489.75?mg catechin equivalents/g dry weight). The EtOAc fraction of flowers exhibit a higher activity in each antioxidant system with a special attention for DPPH assay (IC₅₀?=?0.017?mg/mL) and reducing power (EC₅₀?=?0.02?mg/mL). The EtOAc and n-BuOH fractions of stems and leaves showed strong inhibition of AChE (IC₅₀?=?0.016 and 0.029?mg/mL, respectively).

Discussion and conclusions: These results suggest the potential of S. arenaria as a possible source of novel compounds and as an alternative antioxidant and AChEIs.     

响应面法优化松花粉总酚的超声提取工艺

目的:优选松花粉中总酚的超声提取工艺.方法:以总酚得率为指标,采用单因素试验考察乙醇体积分数、超声时间、超声温度、料液比等因素对总酚得率的影响,在此基础上,运用响应面法优选总酚超声提取工艺.结果:松花粉总酚的最佳超声提取工艺条件为30倍量39％乙醇于51℃下超声提取24 min,在此条件下,总酚得率3.85 mg·g-1,实测值与模型预测值相符.结论:响应面分析法可较好地用于优化松花粉总酚超声提取工艺,且该优选工艺方便、快捷、高效.