Variation of Taxane Content in Needles of Taxus x media Cultivars with Different Growth Characteristics

Diving into paclitaxel: isolation and screening content from Taxus sumatrana at Singgalang Conservation Center, West Sumatra

The report features the first isolation of paclitaxel from wood of conservated Taxus sumatrana. The T. sumatrana is a nationally protected endemic plant that has been successfully cultivated outside its natural habitat at the Singgalang Conservation Centre in West Sumatra. The paclitaxel was utilised as a reference standard for evaluating its presence in different parts of T. sumatrana. This analysis exhibits that the acetone extract from T. sumatrana bark contained the highest paclitaxel concentration, measuring about 0.473 ± 0.031 ppm. The isolated paclitaxel demonstrated potent cytotoxic activity against A549, HeLa, and MCF7 cancer cells, by IC50 values of 3.26 ± 0.334, 2.85 ± 0.257, and 3.81 ± 0.013 μM, respectively. This outcome provides scientific support for conservation programs and campaigns for the community to engage in conservation efforts.

Natural Taxanes: From Plant Composition to Human Pharmacology and Toxicity

Biologically active taxanes, present in small- to medium-sized evergreen conifers of various Taxus species, are widely used for their antioxidant, antimicrobial and anti-inflammatory effects, but mostly for their antitumour effects used in the treatment of solid tumours of the breast, ovary, lung, bladder, prostate, oesophagus and melanoma. More of the substances found in Taxus plant extracts have medical potential. Therefore, at the beginning of this review, we describe the methods of isolation, identification and determination of taxanes in different plant parts. One of the most important taxanes is paclitaxel, for which we summarize the pharmacokinetic parameters of its different formulations. We also describe toxicological risks during clinical therapy such as hypersensitivity, neurotoxicity, gastrointestinal, cardiovascular, haematological, skin and renal toxicity and toxicity to the respiratory system. Since the effect of the drug-form PTX is enhanced by various Taxus spp. extracts, we summarize published clinical intoxications and all fatal poisonings for the Taxus baccata plant. This showed that, despite their significant use in anticancer treatment, attention should also be focused on the risk of fatal intoxication due to ingestion of extracts from these plants, which are commonly found in our surroundings.

Production of bioactive plant secondary metabolites through in vitro technologies-status and outlook

Medicinal plants have been used by mankind since ancient times, and many bioactive plant secondary metabolites are applied nowadays both directly as drugs, and as raw materials for semi-synthetic modifications. However, the structural complexity often thwarts cost-efficient chemical synthesis, and the usually low content in the native plant necessitates the processing of large amounts of field-cultivated raw material. The biotechnological manufacturing of such compounds offers a number of advantages like predictable, stable, and year-round sustainable production, scalability, and easier extraction and purification. Plant cell and tissue culture represents one possible alternative to the extraction of phytochemicals from plant material. Although a broad commercialization of such processes has not yet occurred, ongoing research indicates that plant in vitro systems such as cell suspension cultures, organ cultures, and transgenic hairy roots hold a promising potential as sources for bioactive compounds. Progress in the areas of biosynthetic pathway elucidation and genetic manipulation has expanded the possibilities to utilize plant metabolic engineering and heterologous production in microorganisms. This review aims to summarize recent advances in the in vitro production of high-value plant secondary metabolites of medicinal importance.

Key points

• Bioactive plant secondary metabolites are important for current and future use in medicine

• In vitro production is a sustainable alternative to extraction from plants or costly chemical synthesis

• Current research addresses plant cell and tissue culture, metabolic engineering, and heterologous production

Dataset of Targeted Metabolite Analysis for Five Taxanes of Hellenic Taxus baccata L. Populations

Novel primary sources of one of the world’s leading anticancer agent, paclitaxel, as well as of other antineoplastic taxanes such as 10-deacetylbaccatin-III, are needed to meet an increasing demand. Among the Taxus species the promise of Taxus baccata L. (European or English yew) has been documented. In this study, the metabolite analysis of two marginal T. baccata populations in Greece (Mt. Cholomon and Mt. Olympus), located at the southeastern edge of the species natural distribution, are being explored. A targeted liquid chromatography – mass spectrometry (LC-MS/MS) analysis was used to determine the content of 10-deacetylbaccatin III, baccatin III, 10-deacetyltaxol, paclitaxel and cephalomannine in the needles of each of the populations from three sampling periods (spring, summer and winter). This is the first survey to generate a taxane targeted metabolite data set, since it derives from Hellenic natural populations that have not been explored before. Furthermore, it has used an extensive sample design in order to evaluate chemodiversity at the population level. The analysis revealed significant levels of chemodiversity within and among the investigated populations and significant seasonal variation that could be exploited for the selection of superior germplasm native to Greece, for yew plantations and further exploitation which is necessary for the production of important taxanes.

Comparative Transcriptome Analysis Revealed the Tissue-Specific Accumulations of Taxanes among Three Experimental Lines of Taxus yunnanensis

Taxus yunnanensis (Yew) is known for natural anticancer metabolite paclitaxel (Taxol) and its biosynthesis pathway in yew species still needs to be completely elucidated. In the current study, productions of paclitaxel and 10-DAB III from three different tissues (needle, branch, and root) of T. yunnanensis wild type (WT) and two new cultivars Zhongda-1 (Zd1) and Zhongda-2 (Zd2) were determined, and significant tissue differences in contents of the taxanes were observed among the three experimental lines. The much higher 10-DAB III and lower paclitaxel contents in needle of Zd2 when compared with that of Zd1 indicated the low conversion from 10-DAB III to paclitaxel in the needle of Zd2. In order to uncover the mechanisms of the tissue-specific biosynthesis of the taxanes, transcriptome analysis of cultivar Zd2 was conducted, and the previously reported transcriptome data of Zd1 and WT were used to perform a comparison. The enhancement of TDAT and T10βH side biosynthetic pathway in roots of Zd2 in early taxane synthesis might lead to the biosynthesis of other toxoids, while the preference of T13αH route in the needle and branch of Zd2 was mainly responsible for the tissue-specific reinforced biosynthesis of 10-DAB III and paclitaxel in Zd2. Different from Zd1, the tissue-specific pattern of paclitaxel biosynthesis genes in Zd2 was similar to WT. However, the lower transcript abundance of final steps genes (TBT, DBAT, BAPT, and DBTNBT) of the paclitaxel biosynthesis pathway in Zd2 than in Zd1 might further promote 10-DAB III accumulation in Zd2.

Taxus ingredients in the red arils of Taxus baccata L. determined by HPLC-MS/MS

INTRODUCTION

Taxus baccata L. is an evergreen conifer whose plant parts are cardiotoxic. Only the red arils of the berries are described as non-toxic and taxane-free.

OBJECTIVE

Extraction and HPLC-MS/MS methods were developed for the investigation of the Taxus compounds 3,5-dimethoxyphenol, 10-deacetylbaccatin III, baccatin III, cephalomannine, taxol A and taxinine M in the red arils of the yew berries.

METHODOLOGY

A liquid-liquid extraction method for the red arils of the fruits from three yews were developed. An accurate (ESI+) HPLC-MS/MS method was performed for the simultaneous detection and determination of the target compounds in multiple reaction monitoring (MRM) mode.

RESULTS

All Taxus agents obtained were detected in the red arils. Highest concentrations were determined for baccatin III and 10-deacetylbaccatin III.

CONCLUSION

The developed quantitative method is reliable and selective and was successfully applied for quantification of selected Taxus ingredients in red arils of Taxus baccata. It was disproved that the red arils of the berries do not contain the selected Taxus compounds.

A fungal endophyte induces transcription of genes encoding a redundant fungicide pathway in its host plant

BACKGROUND

Taxol is an anti-cancer drug harvested from Taxus trees, proposed ecologically to act as a fungicide. Taxus is host to fungal endophytes, defined as organisms that inhabit plants without causing disease. The Taxus endophytes have been shown to synthesize Taxol in vitro, providing Taxus with a second potential biosynthetic route for this protective metabolite. Taxol levels in plants vary 125-fold between individual trees, but the underlying reason has remained unknown.

RESULTS

Comparing Taxus trees or branches within a tree, correlations were observed between Taxol content, and quantity of its resident Taxol-producing endophyte, Paraconiothyrium SSM001. Depletion of fungal endophyte in planta by fungicide reduced plant Taxol accumulation. Fungicide treatment of intact plants caused concomitant decreases in transcript and/or protein levels corresponding to two critical genes required for plant Taxol biosynthesis. Taxol showed fungicidal activity against fungal pathogens of conifer wood, the natural habitat of the Taxol-producing endophyte. Consistent with other Taxol-producing endophytes, SSM001 was resistant to Taxol.

CONCLUSIONS

These results suggest that the variation in Taxol content between intact Taxus plants and/or tissues is at least in part caused by varying degrees of transcriptional elicitation of plant Taxol biosynthetic genes by its Taxol-producing endophyte. As Taxol is a fungicide, and the endophyte is resistant to Taxol, we discuss how this endophyte strategy may be to prevent colonization by its fungal competitors but at minimal metabolic cost to itself.