Structure-radical scavenging activity relationship of alkannin/shikonin derivatives

Alkannins and shikonins (A/S) are naturally occurring isohexenylnaphthazarins (IHNs) of great interest in the field of life sciences due to their broad spectrum of biological properties and are used as food colourants in some countries. In the present study for the first time assessment of the radical scavenging activity of A/S and selected derivatives was carried out using the Crocin Bleaching Assay (CBA) and a modified DPPH assay. Exploration of structure-radical scavenging activity relationship (SAR) was approached with a wide range of A/S derivatives. To accomplish this task, a computational approach was also employed for the two enantiomers and other structurally related compounds. The findings indicated that the side chain –OH group at C-1′ has a positive effect to the radical scavenging properties of alkannin/shikonin by assisting hydrogen atom donation from this carbon atom. Thus, alkannin and shikonin were more potent than deoxyshikonin. Esterification of that hydroxyl group was critical for the activity of the respective compounds (acetyl-, isovaleryl- and β,β-dimethylacryl-shikonin). All of the examined IHN derivatives were found experimentally less potent scavengers than naphthazarin.     

2种紫草中紫草素提取工艺优化及含量比较

优化微波提取2种紫草中紫草素的工艺条件,并对紫草素的含量进行比较。采用单因素和正交试验,研究提取溶剂、提取温度、提取时间和料液比对微波法提取2种紫草中紫草素的影响,优选最佳提取工艺条件并比较紫草素含量。结果表明,微波提取软紫草的紫草素得率高于硬紫草,最佳工艺条件为:提取溶剂90%乙醇、提取温度80℃、提取时间9 min、料液比1︰12(g/mL),此条件下紫草素含量为2.49%。软紫草中紫草素含量高于硬紫草,所选软紫草最佳提取工艺稳定可行、重现性好、色素得率高。     

紫草色素的稳定性及在羊毛上的染色性能

用无水乙醇提取紫草色素,并对其稳定性以及在羊毛上的染色性能进行了研究分析。实验结果表明：紫草色素具有良好的热稳定性及耐弱酸稳定性;较高的染色温度、弱酸性条件有利于紫草色素在羊毛纤维上获得较高的得色率;媒染剂的加入使织物呈现不同的颜色特征值,具有氧化性或还原性的媒染剂如Cr^6 、Sn^2 、Fe^2 会破坏紫草色素的结构,使织物的色光发生变化。     

细胞固定化条件对紫草细胞生产紫草色素的影响

以海藻胶做包埋剂,研究了固化液构成、细胞包埋量和胞龄对紫草色素合成的影响。结果表明：固定化细胞合成紫草色素的合适固化液为含有０．１ｍｏｌ／ＬＣａＣｌ２的紫草色素生产培养基,该固化条件比较温和,并可长久保持固定化细胞活性;最适宜的细胞包埋质量分数为１０％２０％;用于细胞包埋的最佳细胞生长时间为１７ｄ。对紫草细胞固定化培养生产紫草色素过程的动力学特征进行了分析,建立了基质消耗和色素合成的动力学模型,并用该模型对实验数据进行了回归分析,实验数据与理论值之间具有比较令人满意的一致性     

反应性抗紫外剂改性天然染料紫草素北大核心CSCD

为提高紫草素水溶性和紫外线吸收性能,采用水溶性、反应性紫外线吸收剂对天然染料紫草素进行改性,本文合成了一种新型水溶性紫草素染料。通过单因素条件实验确定了改性反应的最佳条件,分析了反应机理,对反应物和产物进行了FTIR红外光谱和紫外光谱表征。结果表明,改性反应最佳条件为紫草素与抗紫外剂的近似摩尔比约1︰0.8,在pH值为9.0的碳酸钠溶液中,80℃水浴振荡40 min。改性紫草素在1 250 cm^(-1)处出现芳香醚中C—O(Φ)键的反对称伸缩振动,紫外-可见吸收光谱显示在波长288 nm处出现吸收峰,且可见光区吸光度增加。通过改性提高了紫草素的水溶性和紫外线吸收性能,用于织物染色可以提高织物的功能性和附加值。     

Nec-1 Enhances Shikonin-Induced Apoptosis in Leukemia Cells by Inhibition of RIP-1 and ERK1/2

Necrostatin-1 (Nec-1) inhibits necroptosis by allosterically inhibiting the kinase activity of receptor-interacting protein 1 (RIP1), which plays a critical role in necroptosis. RIP1 is a crucial adaptor kinase involved in the activation of NF-κB, production of reactive oxygen species (ROS) and the phosphorylation of mitogen activated protein kinases (MAPKs). NF-κB, ROS and MAPKs all play important roles in apoptotic signaling. Nec-1 was regarded as having no effect on apoptosis. Here, we report that Nec-1 increased the rate of nuclear condensation and caspases activation induced by a low concentration of shikonin (SHK) in HL60, K562 and primary leukemia cells. siRNA-mediated knockdown of RIP1 significantly enhanced shikonin-induced apoptosis in K562 and HL60 cells. Shikonin treatment alone could slightly inhibit the phosphorylation of ERK1/2 in leukemia cells, and the inhibitory effect on ERK1/2 was significantly augmented by Nec-1. We also found that Nec-1 could inhibit NF-κB p65 translocation to the nucleus at a later stage of SHK treatment. In conclusion, we found that Nec-1 can promote shikonin-induced apoptosis in leukemia cells. The mechanism by which Nec-1 sensitizes shikonin-induced apoptosis appears to be the inhibition of RIP1 kinase-dependent phosphorylation of ERK1/2. To our knowledge, this is the first study to document Nec-1 sensitizes cancer cells to apoptosis.