Enhancement of paclitaxel production by temperature shift in suspension culture of Taxus chinensis

Recent Advances in Metabolic Engineering, Protein Engineering, and Transcriptome-Guided Insights Toward Synthetic Production of Taxol

The diterpenoid paclitaxel (Taxol®) is a blockbuster anticancer agent that was originally isolated from the Pacific yew (Taxus brevifolia) five decades ago. Despite the wealth of information gained over the years on Taxol research, there still remains supply issues to meet increasing clinical demand. Although alternative Taxol production methods have been developed, they still face several drawbacks that cause supply shortages and high production costs. It is highly desired to develop biotechnological production platforms for Taxol, however, there are still gaps in our understanding of the biosynthetic pathway, catalytic enzymes, regulatory and control mechanisms that hamper production of this critical drug by synthetic biology approaches. Over the past 5 years, significant advances were made in metabolic engineering and optimization of the Taxol pathway in different hosts, leading to accumulation of taxane intermediates. Computational and experimental approaches were leveraged to gain mechanistic insights into the catalytic cycle of pathway enzymes and guide rational protein engineering efforts to improve catalytic fitness and substrate/product specificity, especially of the cytochrome P450s (CYP450s). Notable breakthroughs were also realized in engineering the pathway in plant hosts that are more promising in addressing the challenging CYP450 chemistry. Here, we review these recent advances and in addition, we summarize recent transcriptomic data sets of Taxus species and elicited culture cells, and give a bird's-eye view of the information that can be gleaned from these publicly available resources. Recent mining of transcriptome data sets led to discovery of two putative pathway enzymes, provided many lead candidates for the missing steps and provided new insights on the regulatory mechanisms governing Taxol biosynthesis. All these inferences are relevant to future biotechnological production of Taxol.

Optimization of a broth conductivity controlling strategy directed by an online viable biomass sensor for enhancing Taxus cell growth rate and Taxol productivity

In this work, we investigated the effects of a constant broth conductivity controlling strategy directed by an online viable biomass sensor on Taxol productivity ofTaxus chinensisvar.maireiin suspension cultivation.

Effects of Selected Physicochemical Parameters on Zerumbone Production of Zingiber zerumbet Smith Cell Suspension Culture

Zingiber zerumbet Smith is an important herb that contains bioactive phytomedicinal compound, zerumbone. To enhance cell growth and production of this useful compound, we investigated the growth conditions of cell suspension culture. Embryogenic callus generated from shoot bud was used to initiate cell suspension culture. The highest specific growth rate of cells was recorded when it was cultured in liquid Murashige and Skoog basal medium containing 3% sucrose with pH 5.7 and incubated under continuous shaking condition of 70 rpm for 16 h light and 8 h dark cycle at 24°C. Our results also revealed that the type of carbohydrate substrate, light regime, agitation speed, and incubation temperature could affect the production of zerumbone. Although the zerumbone produced in this study was not abundant compared to rhizome of Z. zerumbet, the possibility of producing zerumbone during early stage could serve as a model for subsequent improvement.

Medicinal plant cell suspension cultures: pharmaceutical applications and high-yielding strategies for the desired secondary metabolites

The development of plant tissue (including organ and cell) cultures for the production of secondary metabolites has been underway for more than three decades. Plant cell cultures with the production of high-value secondary metabolites are promising potential alternative sources for the production of pharmaceutical agents of industrial importance. Medicinal plant cell suspension cultures (MPCSC), which are characterized with the feature of fermentation with plant cell totipotency, could be a promising alternative "chemical factory". However, low productivity becomes an inevitable obstacle limiting further commercialization of MPCSC and the application to large-scale production is still limited to a few processes. This review generalizes and analyzes the recent progress of this bioproduction platform for the provision of medicinal chemicals and outlines a range of trials taken or underway to increase product yields from MPCSC. The scale-up of MPCSC, which could lead to an unlimited supply of pharmaceuticals, including strategies to overcome and solution of the associated challenges, is discussed.

Paclitaxel: a review of adverse toxicities and novel delivery strategies

Better known as Taxol (Bristol-Myers Squibb), paclitaxel is the first member of the taxane family to be used in cancer chemotherapy. The taxanes exert their cytotoxic effect by arresting mitosis through microtubule stabilization, resulting in cellular apoptosis. The use of paclitaxel as a chemotherapeutic agent has become a broadly accepted option in the treatment of patients with ovarian, breast and non-small cell lung cancers, malignant brain tumors, and a variety of other solid tumors. However, significant toxicities, such as myelosuppression and peripheral neuropathy, limit the effectiveness of paclitaxel-based treatment regimens. This review addresses the toxicities associated with paclitaxel treatment and describes existing and future strategies of paclitaxel administration directed at limiting these toxicities.

Taxanes: perspectives for biotechnological production

Taxol is a valuable plant-derived drug showing activity against various cancer types. Worldwide efforts had been made to overcome the supply problem, because the supply by isolation from the bark of the slow-growing yew trees is limited. Plant cell cultures as well as chemical and biotechnological semisynthesis are processes, which are intensively investigated for the production of taxanes paclitaxel (Taxol) and docetaxel (Taxotere) in the last few years. This article provides a comparison of the current research on taxane biosynthesis and production in yew cell cultures.

Evaluation of paclitaxel rearrangement involving opening of the oxetane ring and migration of acetyl and benzoyl groups

The stability of drug is a critical factor in quality control, drug efficacy, safety, storage, and production conditions. The rearrangement of paclitaxel, which involves opening of the oxetane ring and migration of acetyl group occurred on heating a powder of purified paclitaxel. Subsequently, the unusual migration of benzoyl groups progressed rapidly in organic solvents. These rearrangement derivatives were isolated carefully. The structures of the intermediate derivative A and the product derivative B were confirmed using (1)H NMR, high performance liquid chromatography (HPLC), and mass spectrometry. We proposed the rearrangement pathway here for the first time. Neither derivative exhibited bioactivity in SKOV3 (ovarian cancer) or MDA-MB-435 (breast cancer) cell culture assays.

Large-scale purification of 13-dehydroxybaccatin III and 10-deacetylpaclitaxel, semi-synthetic precursors of paclitaxel, from cell cultures of Taxus chinensis

The taxane derivatives 13-dehydroxybaccatin III (13-DHB III) and 10-deacetylpaclitaxel (10-DAP) can be used as semi-synthetic precursors of paclitaxel. These precursors were isolated in a simple and economical procedure during purification of paclitaxel from plant cell culture extracts. No additional costs for cell culture or extraction by silica-gel low-pressure chromatography were incurred. Precipitation from dichloromethane/n-hexane followed by HPLC on ODS and silica-gel resins resulted in paclitaxel of 99.5% purity with 80% overall yield. ODS low-pressure chromatography and THF/n-hexane precipitation yielded 13-dehydroxybaccatin III at >99% purity with 87.1% overall yield, and ODS low-pressure chromatography alone yielded 10-deacetylpaclitaxel at >90% purity with 93.4% overall yield. These compounds are of sufficient purity for use in semi-synthesis of paclitaxel. Both compounds were obtained in high yield at >99.5% purity using ODS-HPLC. The procedures described allow the simultaneous purification of 13-dehydroxybaccatin III, 10-deacetylpaclitaxel, and paclitaxel with only minimal additional expense for reagents or equipment.

WITHDRAWN: The safety of synthetic paclitaxel by intralesional delivery with OncoGeltrade mark into skin breast cancer metastases: method and results of a clinical pilot trial

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Plant cell culture for production of paclitaxel and other taxanes

Great advances in cell cultures of Taxus spp. for production of Taxol (generic name: paclitaxel) and other taxanes (taxoids) have been achieved in the past decade. This article reviews the manipulation of inducing factors--elicitors, gas composition, osmotic pressure, and conditioned medium; bioprocessing strategies--combining of inducing techniques, two-phase and two-stage cultivation, semi-continuous and perfusion cultures, and feeding of precursors or sugars; and bioreactors and scale-up. Perspectives on a more rational and efficient process involving metabolic engineering are also discussed.

Plant cells: secondary metabolite heterogeneity and its manipulation

This chapter proposes the concept of rational manipulation of secondary metabolite heterogeneity in plant cell cultures. The heterogeneity of plant secondary metabolites is a very interesting and important issue because these structure-similar natural products have different biological activities. Both taxoids and ginsenosides are two kinds of preeminent examples in the enormous reservoir of pharmacologically valuable heterogeneous molecules in the plant kingdom. They are derived from the five-carbon precursor isopentenyl diphosphate, produced via the mevalonate or the non-mevalonate pathway. The diterpenoid backbone of taxoids is synthesized by taxadiene synthase and the triterpenoid backbone of ginsenosides is synthesized by dammarenediol synthase or beta-amyrin synthase. After various chemical decorations (oxidation, substitution, acylation, glycosylation, benzoylation, and so on) mediated by P450-dependent monooxygenases, glycosyltransferases, acyltransferases, benzoyltransferases, and other enzymes, the terpenoid backbones are converted into heterogeneous taxoids and ginsenosides with different bioactivities. Although detailed information about accumulation and regulation of individual taxoids or ginsenosides in plant cells is still lacking, remarkable progress has recently been made in the structure and bioactivity identification, biosynthetic pathway, manipulation of their heterogeneity by various methodologies including environmental factors, biotransformation, and metabolic engineering in cell/tissue cultures or in plants. Perspectives on a more rational and efficient process to manipulate production of desired plant secondary metabolites by means of metabolic engineering and "omics"-based approaches (e.g., functional genomics) are also discussed.