Bioprocess engineering of <Emphasis Type="Italic">Echium italicum</Emphasis> L.: induction of shikonin and alkannin derivatives by two-liquid-phase suspension cultures

An in vitro cell suspension culture of Echium italicum was established and assayed for the production of shikonin and alkannin derivatives. Callus tissues were induced from cotyledon explants of the plant incubated onto the solidified B5 medium. A two-liquid-phase system suspension culture was then established to elicit pigments of shikonin and alkannin derivatives using liquid paraffin. The presence of liquid paraffin efficiently induced production of pigments in cultured cells. The production and/or accumulation of these compounds in the E. italicum cells was examined using fluorescence microscopy as the naphthoquinone molecules display autofluorescent properties. Phytochemical analysis of the n-hexane extract of the medium was also carried out using preparative HPLC. The chemical structure of shikonin and alkannin derivatives were characterized by UV, 1H-NMR, and 13C-NMR techniques. Based on our findings, this bioprocess engineering approach resulted in induction of shikonin and alkannin derivatives, whereupon it may be recruited for production of these important secondary metabolites.     

Synthesis and human telomeric G-quadruplex DNA-binding activity of glucosaminosides of shikonin/alkannin

The N-acetyl glucosaminosides of shikonin/alkannin were synthesized by chemical glycosylation, which provided an ideal approach to resolve the mixture of enantiomeric shikonin and alkannin co-existed in the Chinese herbs. The glycosylated shikonin and alkannin exhibited stronger binding activity to human telomeric G-quadruplex DNA than their parent structures. This research indicated that glycosylation of natural product with amino sugars is an effective strategy to improve their DNA-binding affinity.     

外循环气升式反应器培养新疆紫草细胞

采用两步培养法进行新疆紫草细胞悬浮培养及5L外循环气升式反应器扩大培养,探讨了培养过程中细胞生长、紫草色素合成与培养液的电导率、可溶性糖含量变化之间的关系。第一步培养时细胞生长迅速,但也有一部分色素合成,电导率及可溶性糖含量迅速下降;第二步培养初期电导率也开始下降,但当色素合成达到高峰并有一部分外泌到培养基后,电导率又开始回升。可溶性糖捎耗很快,到后期巳测不出其存在。因此通过监测培养液中电导率及可溶性糖的变化情况,可以为新疆紫草细胞大规模培养与色素合成提供有用的参数指标。     

Antitumor Activity of DMAKO-05, a Novel Shikonin Derivative,and Its Metabolism in Rat Liver Microsome

The antitumor activity of shikonin derivatives is largely dependent on the generation of superoxide radicals and the alkylation activity of their naphthoquinone moiety. However, our recent study showed that 1,4-dioxime-5,8-dimethoxynaphthalene (DMAKO-05), a novel shikonin derivative, displayed more potential antitumor activity and less toxicity compared to fluorouracil (5-FU) both in vitro and in vivo, even though the hydroxyl and carbonyl groups of its naphthoquinone structure were shielded. To understand the underlying mechanisms, we investigated the metabolism of DMAKO-05 in rat liver microsomes. The kinetic analysis indicated that DMAKO-05 underwent a biphasic metabolism in rat liver microsomes. The inhibition experiments showed that CYP1A and CYP3A were the major enzymes in the metabolism of DMAKO-05, along with partial contribution from CYP2A. In addition, the structures of eight DMAKO-05 metabolites, which were characterized by accurate mass and MS/MS fragmentograms, implied that DMAKO-05 was mainly metabolized through the oxygenation of its naphthoquinone nucleus and the hydrolysis of its side chain, instead of the oxidation of hydroxyimine to ketone. Therefore, DMAKO-05 should not be considered as a traditional naphthoquinone prodrug.KEY WORDS: antitumor, LC-TOF-MS/MS, metabolism, method validation, rat hepatic microsomes, shikonin oxime     

Formation of stereoisomeric mixtures of naphthoquinone derivatives in Echium lycopsis callus cultures

Callus cultures of Echium lycopsis were shown to produce a large amount of a mixture of red pigments consisting of five esterified derivatives of 5,8-dihydroxy-2-(1-hydroxy-4-methyl-3-pentenyl)-1,4-naphthoquinone. Examination of the absolute configuration of these compounds revealed that the cultures produced both the R-form (shikonin) and the S-form (alkannin) in various ratios depending upon the esterified derivative, although the overall ratio for the total derivatives was ca 1:1. On the other hand, all the corresponding derivatives produced by Lithospermum cultures were primarily of the R-form. It was also demonstrated that pigment formation in Echium cultures was inhibited by either white or blue light as well as by the synthetic auxin 2,4-D as in the case of Lithospermum cultures.     

Induction of benzoquinone formation by activated carbon in Lithospermum erythrorhizon cell suspension cultures

Cultured cells of Lithospermum erythrorhizon which were capable of producing red naphthoquinone (shikonin) derivatives on Linsmaier-Skoog's agar medium stopped synthesizing these compounds when grown in liquid medium without agar. However, when the liquid medium was supplemented with a small amount of activated carbon, the cells produced a new orange benzoquinone derivative, echinofuran B, which may be considered an abnormal metabolite of geranylquinol, the key intermediate in the biosynthesis of shikonin. A similar effect of activated carbon was also observed with a variant cell line incapable of producing shikonin derivatives even on the agar medium. By contrast, the callus cultures grown on the agar medium as well as the dried roots of the intact plant were found to contain a small amount of echinofuran C, another new benzoquinone related to echinofuran B, in addition to shikonin derivatives.     

Halohydrin and oxime derivatives of radicicol: synthesis and antitumor activities

Novel halohydrin and oxime derivatives of radicicol (1) were prepared and evaluated for their v-src tyrosine kinase inhibitory, antiproliferative, and antitumor activities. Some of the resulting derivatives showed significantly improved antitumor activities than those of 1 in vitro as tested in a cell proliferation assay and in vivo using sc-inoculated human breast carcinoma and epidermoid tumor models. Design and synthesis of radicicol-based novel affinity probes are also described.     

10升气升环流式生物反应器培养紫草细胞

本文采用自行设计研制的10升气升环流式生物反应器培养紫草细胞,培养周期34d．前14d为细胞生长培养,细胞生长呈正常的S型曲线,细胞增长到原细胞接人量的4倍．后20d为紫草色素生产培养,细胞增长到32倍。整个周期每升培养液可生产紫草色素0．6g,在反应器中,培养液pH值的变化与细胞生长呈正相关,与紫草色素的形成呈负相关,pH值变化规律可用于监测紫草细胞在生物反应器的生长和色素形成．     

Pigment production from in vitro cultures of Alkanna tinctoria Tausch

Summary An in vitro culture of Alkanna tinctoria Tausch cells was set up in order to investigate the possibility of producing alkannin, a red naphthoquinone naturally present in the root bark of this plant. Furthermore, an in vitro culture of callusderived roots was established and the production of alkannin evaluated. In the different experimental conditions investigated, differences in the production of alkannin derivatives as well as in the type of pigments produced, were observed. The potential use of this technology is discussed.     

Production of shikonin derivatives by cell suspension cultures of Lithospermum erythrorhizon

Differences in the production of shikonin derivatives by callus and suspension cultures of Lithospermum erythrorhizon Sieb. et Zucc. were examined. When Linsmaier and Skoog medium was used in suspension cultures, cell growth was not accompanied by the production of shikonin compounds. Shikonin derivatives were produced, however, when this medium was used in callus cultures. Differences in shikonin production were examined in terms of the nutrient supply, the effect of the agar itself, and the oxygen supply. Shikonin derivatives could be produced without agar by keeping the cells exposed to air while providing an adequate supply of nutrients. In callus cultures, the production of shikonin compounds was reduced remarkedly when the oxygen concentration in the atmosphere was lowered, evidence that shikonin production during L. erythrorhizon cell growth on Linsmaier and Skoog agar medium is enhanced by an abundant supply of oxygen.     

Production of shikonin derivatives by cell suspension cultures of Lithospermum erythrorhizon. III. Comparison of shikonin derivatives of cultured cells and ko-shikon

A method for quantitative analysis of shikonin derivatives using high pressure liquid chromatography (HPLC) was established. With this method the composition of shikonin derivatives in cultured cells and roots of Lithospermum erythrorhizon (ko-shikon) was compared. The composition of shikonin derivatives produced by cell suspension cultures was similar to that of the ko-shikon, and the composition in cultured cells was found to fluctuate less than that of the ko-shikon.     

A natural anthraquinone derivative shikonin synergizes with AZD9291 against wtEGFR NSCLC cells through reactive oxygen species-mediated endoplasmic reticulum stress

BackgroundNSCLC is the major type of lung cancer and the survival rates of NSCLC patients remain low. AZD9291 is a third-generation EGFR-TKI and approved to treat NSCLC patients harboring EGFR T790M mutation and common targetable activating EGFR mutations, but it has a limited effect for wtEGFR NSCLC.PurposeThe current study investigated whether shikonin could enhance the antitumor effect of AZD9291 in wtEGFR NSCLC cells.MethodsSRB and colony formation assay were used to detect the proliferation of NSCLC cells, propidium iodide staining was performed to detect the apoptosis, ROS was analyzed using DCFH-DA staining, and western blot was used to detect the expression of indicated proteins.ResultsWe demonstrated that shikonin, a natural ROS inducer, could enhance the antitumor effect of AZD9291 in wtEGFR NSCLC cells. In addition, shikonin increased AZD9291-induced apoptosis accompanying with the generation of ROS and activation of ER stress. Furthermore, ROS inhibition by NAC or GSH reversed the apoptosis induced by shikonin plus AZD9291, and recovered the ER stress activated by combination treatment, indicating that ROS mediated ER stress played a vital role in this combination therapy. Moreover, shikonin increased the anticancer activity of AZD9291 in primary wtEGFR NSCLC cells through ROS-mediated ER stress.ConclusionOur study suggests that combining shikonin with AZD9291 is a promising therapeutic strategy for treating wtEGFR NSCLC patients.     

Physico-chemical factors influencing the shikonin derivatives production in cell suspension cultures of Arnebia euchroma (Royle) Johnston, a medicinally important plant species

Cell suspension cultures of Arnebia euchroma were raised from in vitro leaf-derived friable callus on liquid MS [Murashige and Skoog] medium supplemented with BAP (6-benzylaminopurine) (10.0 μM) and IBA (indole-3-butyric acid) (5.0 μM). A two-stage culture system was employed using growth and production medium for cell biomass and shikonin derivatives, respectively. Factors such as light, temperature, sucrose and pH (hydrogen ion concentration) were studied to observe their effect on the shikonin derivative production. Light conditions completely inhibited shikonin derivative production. Out of different temperature regimes tested, the highest yield (586.17 μg/g FW) was found at 25°C. Maximum production (656.14 μg/g FW) was observed in 6% sucrose. An alkaline pH (7.25-9.50) favoured shikonin derivative production. The results showed that physical and chemical factors greatly influence the production of shikonin derivatives in cell suspension cultures of A. euchroma. Therefore, by employing optimum culture conditions, it is possible to enhance the production of secondary compounds from the cells. The factors optimized for in vitro production of shikonin derivatives during the present study can successfully be employed for their large-scale production in bioreactors.     

Enzyme activity and shikonin production in Lithospermum erythrorhizon cell cultures

The activities of the biosynthetic enzmes phenylalanine ammonia lyase (PAL) and 3-hydroxy-3-methylglutaryl-CoA-reductase (HMGR) were measured in cells transferred from growth to production medium in a two-stage batch culture. It was found that both these enzymes showed transient increases, PAL (three- to fourfold) and HMGR (two- to four-fold), at or near the point of exhaustion of nitrogen source (NO(3)). Production of shikonin derivatives also started at this time. The addition of excess nitrate to the medium shortly before nitrate exhaustion (days 6-8) markedly reduced the final product yield (by 70-80%) while addition of excess nitrate in the later stationary growth phase (days 14-16) had no significant effect. When the production rate of shikonin derivatives was correlated with PAL activity, it was observed that production rate is very low (less than 1 mg/L . day) at low levels of PAL activity (below 0.1 unit/mg protein). Once a threshold level of PAL activity (about 0.15 unit/mg protein) is reached, the biosynthetic rate of shikonin derivatives increases. Such a relationship could not be deduced for HMGR activity. It was concluded that the production of shikonin derivatives may be limited at the phenylalanine deaminating step at low levels of PAL activity.     

The Effective Production of Shikonin by Cultures with an Increased Cell Population

We have studied the efficient production of shikonin derivatives by suspension cultures of Lithospermum erythrorhizon with an increased cell population. The yield of shikonin derivatives was highest (800 mg/liter) when 2.8 g dry wt/liter of the cells was inoculated into the M-2 medium which we had developed for the production, but the excess inoculum lowered the yield.

We investigated suitable conditions for production with the increased cell population. The optimum amount of inoculum rose to 4.9 g dry wt/liter when the concentrations of all the components contained in the M-8 medium, which we developed for increasing the productivity by modification of the M-2 medium, were increased in proportion to the amount of inoculum, and consequently we could increase the yield of the shikonin derivatives from 1400 mg/liter to 1900 mg/liter. Moreover, the increased rate of oxygen supply in addition to the enrichment of the medium made it possible to produce 2300 mg/liter of the shikonin derivatives from a culture for which 5.6 g dry wt/liter of the cells was inoculated.     

固定化培养和产物释放促进剂对硬紫草细胞代谢的影响

固定化培养的硬紫草细胞生长缓慢,仅包埋球外层的细胞生长明显。其蛋白质合成的量也低。培养３０ｄ的细胞色素产量达到４．２ｍｇ／ｇＦＷ,相对色素分泌量达到７０％,而色素的组成成分及各组分的比例也与悬浮细胞的不同。以正十六烷处理固定化细胞可促进产物释放,其不同的处理时间对细胞没有显著影响。连续培养的固定细胞保持其色素形成能力达８０ｄ之久,色素总产量达２０ｍｇ／ｇＦＷ。     

Theoretical investigation of the radical scavenging activity of shikonin and acylshikonin derivatives

The radical scavenging activity of shikonin and acylshikonin derivatives was studied by using density functional theory. The hydrogen bond property of the studied structures was investigated using the atoms in molecules (AIM) theory. It turned out that the hydrogen bond is important for good radical scavenging activity. The hydrogen atom transfer for shikonin and acylshikonin derivatives is difficult to obtain because of the high bond dissociation energy (BDE). However, shikonin and acylshikonin derivatives appear to be good candidates for the one-electron-transfer. The introduction of acyl groups for shikonin decreases the ionization potential (IP) values compared with that of shikonin. The acylshikonin derivatives with 1H-pyrrole, furan, and thiophene groups are expected to be of the highest radical scavenging activity among the compounds investigated in this study. Taking this system as an example, we present an efficient method for the investigation of radical scavenging activity from theoretical point of view.     

硬紫草细胞悬浮培养和紫草宁及其衍生物的形成

硬紫草细胞悬浮培养形成紫草宁及其衍生物时．细胞生长曲线呈扁平的s形。细胞停止生长后,紫草宁及其衍生物大量形成,二者的动态变化呈负相关。测定丁此过程中培养液的无机元素和可溶性糖含量、溶氧、pH值以及细胞形态的变化情况,可作为硬紫草细胞大规模培养的参考。