Solubility study of phytochemical cross-linking agents on dentin stiffness

Objectives

The effects of interactions between cross-linking proanthocyanidins (PA) in polar solvents and type-I collagen of demineralized dentin were investigated.

Methods

Three PA-rich extracts, two from grape seed (GSEP and GSES) and one from cocoa (COE), were dissolved (water, ethanol:water and acetone:water) and analyzed for their ability to increase the modulus of elasticity of demineralized dentin. Sound dentin beams (0.5 mm × 1.7 mm × 7 mm) were fully demineralized and divided into 12 groups according to the type of cross-linking agent and solvents used. Specimens were immersed in the respective solutions and tested at baseline, 10, 30, 60, 120 and 240 min.

Results

The elastic modulus (EM) of dentin was significantly increased by the PA treatment regardless of time (p < 0.05 for all times). The extracts showed different solubility in different solvents. GSEP showed the highest increase in EM when diluted in distilled water and acetone at all exposure times. Both GSEs showed superior results when diluted in distilled water and after 4 h of treatment, while COE produced strongest enhancement when dissolved in ethanol:water.

Conclusions

The results indicates that herbal extraction process and other pharmacognostic parameters have an important influence on extract solubility as well as constitution and, consequently, on the PA–dentin matrix interaction.     

Differential effects of blueberry proanthocyanidins on androgen sensitive and insensitive human prostate cancer cell lines

Blueberries are rich in health-promoting polyphenolic compounds including proanthocyanidins. The purpose of this study was to determine if proanthocyanidin-rich fractions from both wild and cultivated blueberry fruit have the same inhibitory effects on the proliferation of LNCaP, an androgen-sensitive prostate cancer cell line, and DU145, a more aggressive androgen insensitive prostate cancer cell line. When 20 μg/ml of a wild blueberry proanthocyanidin fraction (fraction 5) was added to LNCaP media, growth was inhibited to 11% of control with an IC₅₀ of 13.3 μg/ml. Two similar proanthocyanidin-rich fractions from cultivated blueberries (fractions 4 and 5) at the same concentration inhibited LNCaP growth to 57 and 26% of control with an IC₅₀ of 22.7 and 5.8 μg/ml, respectively. In DU145 cells, the only fraction that significantly reduced growth compared to control was fraction 4 from cultivated blueberries with an IC₅₀ value of 74.4 μg/ml, indicating only minor inhibitory activity. Differences in cell growth inhibition of LNCaP and DU145 cell lines by blueberry fractions rich in proanthocyanidins indicate that blueberry proanthocyanidins have an effect primarily on androgen-dependant growth of prostate cancer cells. Possible molecular mechanisms for growth inhibition are reviewed.     

原花青素A-1调节ConA刺激小鼠脾细胞分泌Th1/Th2细胞因子的影响

目的研究从碎米花杜鹃叶中分离得到的化合物原花青素A-1(proanthocyanidin A-1,简称PAA-1)对Con A刺激的小鼠脾细胞细胞因子分泌水平的调节作用,确定其免疫增强的作用机制。方法采用双抗夹心ELISA法,通过不同浓度PAA-1协同Con A体外刺激,检测其对小鼠脾细胞分泌的各种细胞因子分泌量的影响。结果 1)PAA-1各浓度在体外能增加Con A刺激的脾细胞分泌的辅助性T细胞亚群(Th1)细胞因子(IL-2、IL-12、IFN-γ、TNF-α)的分泌量;2)PAA-1对Con A刺激的脾细胞分泌的抑制Th2细胞因子(IL-4、IL-10)的分泌量起抑制作用。结论 PAA-1是通过增加Con A刺激的小鼠脾细胞Th1细胞因子的分泌量,来发挥免疫增强作用,并使Th1/Th2的平衡向Th1方向移动,这对许多的Th2占优势的免疫紊乱性疾病的治疗具有重要的意义,为其开发为新型免疫增强剂提供试验依据。     

Grape seed proanthocyanidin lowers brain oxidative stress in adult and middle-aged rats

There is growing concern over the increasing instances of decline in cognitive abilities with aging in humans. The present study evaluated the benefits of the natural antioxidant, grape seed proanthocyanidin extract (GSPE) in treating the effects of age-related oxidative stress (OS) and accumulation of lipofuscin (LF) on the cognitive ability in rats. Female Wistar rats of 3- and 12-months of age received a daily oral supplement of GSPE until they attained 6- and 15-months of age. During this period, rats were tested for their cognitive ability. At the end of this period, blood glucose and markers of OS were assessed in the hippocampus. GSPE lowered blood glucose, lipid peroxidation, hydrogen peroxide level, and increased protein sulphydryl (P-SH) content in the hippocampus. In addition, GSPE significantly improved cognitive performance in the two age groups. These results demonstrate that the extent of OS-related LF accumulation is reducible by GSPE. They also suggest a critical role for GSPE as a neuroprotectant in the hippocampus and in preventing cognitive loss with aging.     

Influence of collagen cross-linkers addition in phosphoric acid on dentin biomodification and bonding of an etch-and-rinse adhesive

ObjectiveTo investigate the effects of natural collagen cross-linkers incorporation in phosphoric acid etchant on dentin biomodification, microtensile bond strength (μTBS) and nanoleakage (NL) of a two-step etch-and-rinse adhesive.MethodsExperimental aqueous solution of 37% ortho-phosphoric acid were prepared with the addition of 2% biomodification agents: Lignin (LIG) from industrial paper production residue, Cardanol (CARD) from cashew-nut shell liquid, and Proanthocyanidin (PAC) from grape-seed extract. Negative control (NC) was acid solution without cross-linker whilst commercial control (CC) was Condac 37 gel (FGM). Dentin specimens were assayed by FTIR after 15 s etching to detect collagen cross-linking. Extracted third molars were used for μTBS (n = 7) and fracture mode analysis of Optibond S (Kerr), tested after 24 h or 1000 thermal cycles. NL was surveyed by SEM. Statistical analysis was performed with two-way ANOVA and Tukey’s test (p < 0.05).ResultsFTIR confirmed cross-linking for all agents. μTBS of CC was the highest (46.6 ± 6.2 MPa), but reduced significantly after aging (35.7 ± 5.2 MPa) (p < 0.001). LIG (30.6 ± 3.7 MPa) and CARD (28.3 ± 1.8 MPa) attained similar μTBS which were stable after aging (p > 0.05). Fracture mode was predominantly adhesive. At 24 h, all groups showed presence of silver uptake in hybrid layer, except CARD. After aging, CARD- and LIG-treated specimens exhibited little amount of silver penetration. CC, PAC and NC showed gaps, great nanoleakage at hybrid layer and presence of water channels in adhesive layer.SignificanceAltogether, ortho-phosphoric acid incorporated with LIG and CARD promotes stable resin-dentin bond strength with minor nanoleakage after aging, thereby achieving therapeutic impact without additional clinical steps.     

葡萄籽提取物抗氧化作用人体实验研究

目的研究葡萄籽提取物原花青素对人体丙二醛(MDA)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)的影响情况。方法选择年龄45~65岁的受试者120名,分为试食组和对照组。试食组每人每天2粒服用受试样品,连续3个月,对照组按同法给予安慰剂。比较实验前后受试者的MDA、SOD、GSH-PX改善情况。结果试食组血清中MDA平均下降4.80%;SOD平均升高2.31%;GSH-PX平均升高2.45%,;试食组自身实验前后比较及与对照组组间比较差异均有统计学意义(均P0.01)。结论在研究剂量范围内可见葡萄籽提取物原花青素具有抗氧化功能。     

葡萄籽提取物对人体抗氧化能力的影响

目的：研究葡萄籽提取物对人体抗氧化能力的影响。方法：选年龄在45～65岁的健康志愿者100人,根据血清超氧化物歧化酶（superoxide dismutase,SOD）、谷胱甘肽过氧化物酶（glutathione peroxidase,GSH Px）活性和丙二醛（maleic dialdehyde,MDA）含量,随机分为试食组和对照组,每组50人,试食组受试者每天口服葡萄籽提取物软胶囊1g,连续用3个月,对照组不服药。试验前后每人测一次血清中SOD、GSH-Px、MDA三项指标。结果：试验后试食组血清SOD、GSH-PX显著高于对照组（P均＜0.05）,试食组血清MDA含量显著低于对照组（P＜0.01）;且试食组试验前后自身比较三项指标亦有统计学差异（P均＜0.01）。结论：葡萄籽提取物具有明显的体内抗氧化活性。     

Effect of proanthocyanidin on ultrastructure and mineralization of dentine collagen

ObjectiveProanthocyanidin (PA) is a natural collagen cross-linker that has been used in dentine matrix biomodification for reparative and preventive therapies. This study evaluated the ultrastructure of collagen after its interaction with PA. Furthermore, the mineralization of PA-biomodified collagen matrix was observed.MethodsTen freshly extracted sound human molars were sectioned into 0.5 mm × 1.7 mm × 7 mm beams for ultrastructural evaluation of PA and dentine matrix under Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). Specimens for TEM were completely demineralized and divided into three groups according to PA treatments: deionized water, 2% PA and 6.5% PA. The specimens were fixed, dehydrated, sectioned and examined using TEM. Specimens for FESEM were lightly conditioned with EDTA and similarly divided into the three groups for observation using FESEM. Type I collagen from calf skin was used to analyse the mineral interaction after treatment with 6.5% PA. Formvar- and carbon-coated 400-mesh Ni grids (EMS, Hatfiels, PA, USA) were placed over a 2 mg/mL collagen solution prepared from calf skin-derived Type I collagen to achieve self-assembly of collagen fibrils. Grids were treated with 6.5% PA and divided into two groups. One group was floated over a remineralization solution containing 20 mM HEPES, 2.25 mM CaCl₂-2H₂O, 1.35 mM KH₂PO4, 3.08 mM NaN3 and 130 mM KCl and the other group was over a CPP-ACP solution (Tooth mousse 1:100 dilution with deionized water). The floating samples were kept in a 37 °C and 100% humidity chamber. Grids were taken out at selected time durations (24 h, 48 h and 72 h for mineralization solution/24 h for CPP-ACP) and observed under TEM without staining. Selected area electron diffractions (SAEDs) were performed at 110 kV.ResultsFollowing treatment of demineralized dentine collagen matrix with PA, the size and number of interfibrillar spaces were reduced. The collagen fibrils aggregated together with a reduction in porosity. A characteristic banding pattern of collagen fibrils was observed under TEM. Treatment of PA-biomodified collagen fibrils with remineralization solution increased mineral aggregation along its long axis, when compared to the control group. Furthermore, treatment of PA-biomodified collagen fibrils with CPP-ACP solution enhanced mineral uptake and deposition as well as initiated apatite formation within 24 h.ConclusionProanthocyanidin alters the ultrastructure of demineralized dentine collagen matrix. The PA-biomodified collagen matrix promotes remineralization.     

Do collagen cross-linkers improve dentin’s bonding receptiveness?

Objectives

Dentin biomodification using collagen cross-linkers has been proposed as one of the strategies to improve bond durability of adhesives to dentin. However, literature is not very consistent regarding their benefit, in particular when cross-linkers are applied in clinically realistic application times. This study investigated the effect of three cross-linkers on the mini-interfacial fracture toughness (mini-iFT) of four adhesives bonded to dentin following either etch&rinse (E&R) or self-etch (SE) modes.

葡萄籽提取物原花青素的抗疲劳作用研究

目的　葡萄籽提取物原花青素的抗疲劳作用。　方法　采用雄性昆明种小鼠每天经口给予原花青素 ,剂量分别为 0、1.7、16.7、5 0 .0mg kg体重 ,3 0d后测定负重游泳时间 ,血红蛋白及运动后血乳酸和肝糖原含量。　 结果　各剂量组小鼠负重游泳时间均比对照组延长 ,中、高剂量组具极显著差异 (P <0 .0 1) ,血红蛋白含量均高于对照组 ;各剂量组小鼠运动后血乳酸含量均低于对照组 ,高剂量组与对照组相比具极显著差异 (P <0 .0 1) ;肝糖元含量均高于对照组 ,中、高剂量组与对照组相比分别具显著和极显著差异 (P <0 .0 5 ,P <0 .0 1)。　结论　本实验研究结果表明原花青素具有抗疲劳作用