Importance of yew tree (Taxus spp.) originates from the entering of Taxol (Paclitaxel) in the treatment of breast cancer since 1982. Taxus spp. is one of the Taxaceae family, distributed in North America, Europe, meditranean region, Asia and North forests of Iran. Efficacy of Taxol in the treament of some cancers and low concentration of this compound in tree, stimulated semi synthetic preparation of taxol from other more aboundant compounds such as baccation–III which is found with higher concentrations in all tree tissues. Despite entering some other routs for preparation of taxol e.g. cell culture, cultivation and studies on yew tree is in high importance, therefore review on this plant was made by authors.

Taxol is a diterpeniod with complex structure, which is extracted frequently from the genus Taxus. At present, this drug is one of the most important anticancer natural agents with different mechanism from other similar drugs, used for remedy of different cancers such as, melanoma, lung cancer, non-hodgkins lymphoma, meatus urinarius cancer, esophagus cancer, etc. At present, many scientists are trying total synthesis and semi-synthesis of taxol and also its extraction from cell culture. however, these methods have characteristic problems. The increasing demand of taxol for clinical use as an anticancer drug combined with limited supply from plant sources require a thorough understanding of its biosynthesis and extraction methods.

Conclusion: The injection of single and combine of salaicylic acid and silver nitrate on the Taxus baccata tree showed negative effect on taxol production. It seems that more researchs need to be done in order to understand the acting mechanisms of used elicitors.

Background: Taxol is one of the most important anticancer agents that its supply mainly depends on biological processes. 10 - deacetyl baccatin III- O- acetyl transferase (dbat) gene is one of the key genes in Taxol biosynthetic pathway and it is expected that overexpression of this gene would result in an increased production of taxol in biological systems. Objective: Investigation of dbat gene characteristics from Iranian endemic yew, Gene expression analysis and Construction of overexpression vector for this gene. Methods: First, sequence of the gene was cloned and then, sequence characteristics identified with Bioinformatics analysis. Gene expression analysis was performed under methyl jasmonate elicitation in several time-courses. Finally in order to construct overexpression vector, the sequence was cloned under the control of the CaMV35S promoter in to pCAMBIA1304. Results: Comparison of sequence similarities indicated that this sequence is most similar to Taxus × hunnewelliana. There was one unique amino acid substitution and investigating substituted amino acid revealed that, this replacement can not change overall characteristics of the enzyme and thus it would result in a functional enzyme. Analysis of gene expression showed that in response to methyl jasmonate, gene expression levels increased to maximum rate up to 24 times at 12 hours after elicitation. Finally gene insertion in suitable site of overexpression vector, confirmed by digest with restriction enzymes. Conclusion: Elicitation of shoot cuttings of Taxus would be a suitable alternative for Taxus cell cultures in gene expression analysis. Simplicity, feasibility, and deletion of time-consuming processes of cell culture are its main advantages.

Background: There is an increasing interest in identifying potent cancer preventive and therapeutic agents. Silymarin is a flavonoids complex extracted from the milk thistle (Silybum marianum L.) seeds. Silymarin was found clinically successful in the treatment of various liver diseases. Silymarin is in the focus of cancer researchers due to its high antioxidant properties. Objective: The present study was aimed to investigate the effect of silymarin on 4T1 cells and compared with taxol. Methods: 4T1 cell line (BALB/c mouse mammary tumors) was cultured in RPMI medium containing FBS 10%. Cells were incubated with 5% CO2 in presence of different concentration of silymarin (25-50-75-100-125 µg/ml), taxol (1.25-2.5-5-10-20 nM) and combination of silymarin and taxol separately for 24, 48 and 72 hours. Cell viability was assessed using trypan blue and MTT staining. The cells morphology was studied using fluorescent dye (Hochest, propidium iodide). Results: Silymarin and taxol showed significant cytotoxic effects on breast cancer cell in a dose and time dependent manner. Condensation and deformation of the nuclei were also observed similarly for both treatments. In combination treatment silymarin enhanced the sensitivity of 4T1 cells to taxol in all doses. Conclusion: The cytotoxic effect of silymarin on mouse mammary tumors was comparable to taxol cytotoxicity. Treatment cells with combination of silymarin and taxol improved the cytotoxic effect of taxol.

Background: Hazelnut (Corylus avellana) is a species belonging to the genus Corylus. Its various segments contain different metabolites with very valuable medicinal, anti-microbial and anti-cancer properties. Objective: The present study was done to investigation the optimal conditions for hazelnut plants regenerated from cotyledon as explants and invitrotaxol production. Methods: Cotyledon segments were cultured on MS medium containing 2,4-D concentrations of 0, 0.5 and 1 mgl-1 alone or in combination with concentrations of 0, 0.5 and mgl-1 BA for callus induction. For regeneration, Calli were sub-cultured to the same medium and or transferred to the MS medium containing BA at concentrations of 0, 0.25, 0.5, 1, 2 and 3 mgl-1 Callus was formed in all hormonal treatments. The ability of taxol production in calli was evaluated by adding methyl jasmonat in 0, 10, 40, 70, 100, 130 and 160 µM concentrations. Results: In hormonal treatment including 0.5 mgl-1 2.4-D regeneration was observed. The highest Taxol content (16.7 mg/KgDW) was obtained by adding 130 µM methyl jasmoante against of 4.3 mg/KgDW in control condition. In regenerative treatments maximum number of regenerated shoot (2.5) was in 1 mgl-1 BA. The regenerated shoots were rooted in MS medium containing 2 mg NAA in combination with 0.5 mgl-1 BA. After rooting process, the plantlets with suitable growth (10 cm length) were planted in the mixture of perlite: peat: cocopit in a 1:2:1 ratio and than were placed in a box with a humidity of 90%. The adapted plants were transferred to greenhouse after 4 weeks. Conclusion: This study can be applied as an effective method for callus induction in order to establishment of suspension culture to taxol production and also results can be useful for regeneration of transgenic calli.

Taxol is a very important anticancer drug which was first isolated from Yew plant (Taxus spp.). However, Taxol supply by extraction from natural sources, has several limitations, and cannot meet current market's demands. Therefore, it seems necessary to use alternative production methods. Producing Taxol through biotechnological approaches is among the main options which have some advantages such as independency of production from geographical and environmental conditions, higher production rate, and ease of extraction. This paper contains a review on some of the most important approaches used in Taxol biotechnological production. The main body of the paper is divided into five main parts: (1) Taxol biosynthesis and related genes, (2) Factors and strategies influencing the production of Taxol by plant cell cultures of Taxus spp., (3) Strategies based on genetic manipulation of Taxus spp. for the production of Taxol, (4) Using heterologous systems in taxane production, and (5) Taxol-producing endophytes and related studies. The current status of utilizing biotechnology in producing Taxol and its future outlooks have been also described.