The taxol supply crisis. New NCI policies for handling the large-scale production of novel natural product anticancer and anti-HIV agents

Paclitaxel - a Product of Fungal Secondary Metabolism or an Artefact?

Taxol (common name: paclitaxel) is an extremely important component of drugs for the treatment of various cancers. Thirty years after the discovery of its effectiveness, a metabolic precursor of Taxol (10-deacetylbaccatin III) is still primarily extracted from needles of European yew trees. In order to meet the considerable demand, hopes were pinned on the possibilities of biotechnological production from the very beginning. In 1993, as if by chance, Taxol was supposedly discovered in fungi that grow endobiotically in yew trees. This finding aroused hopes of biotechnological use to produce fungal Taxol in large quantities in fermenters. It never came to that. Instead, a confusing flood of publications emerged that claimed to have detected Taxol in more and more eukaryotic and even prokaryotic species. However, researchers never reproduced these rather puzzling results, and they could certainly not be applied on an industrial scale. This paper will show that some of the misguided approaches were apparently based on a seemingly careless handling of sparse evidence and on at least questionable publications. Apparently, the desired gold rush of commercial exploitation was seductive. Scientific skepticism as an indispensable core of good scientific practice was often neglected, and the peer review process has not exerted its corrective effect. Self-critical reflection and more healthy skepticism could help to reduce the risk of such aberrations in drug development. This article uses this case study as a striking example to show what can be learned from the Taxol case in terms of research ethics and the avoidance of questionable research practices.

Natural compounds targeting YAP/TAZ axis in cancer: Current state of art and challenges

Cancer has become a burgeoning global healthcare concern marked by its exponential growth and significant economic ramifications. Though advancements in the treatment modalities have increased the overall survival and quality of life, there are no definite treatments for the advanced stages of this malady. Hence, understanding the diseases etiologies and the underlying molecular complexities, will usher in the development of innovative therapeutics. Recently, YAP/TAZ transcriptional regulation has been of immense interest due to their role in development, tissue homeostasis and oncogenic transformations. YAP/TAZ axis functions as coactivators within the Hippo signaling cascade, exerting pivotal influence on processes such as proliferation, regeneration, development, and tissue renewal. In cancer, YAP is overexpressed in multiple tumor types and is associated with cancer stem cell attributes, chemoresistance, and metastasis. Activation of YAP/TAZ mirrors the cellular "social" behavior, encompassing factors such as cell adhesion and the mechanical signals transmitted to the cell from tissue structure and the surrounding extracellular matrix. Therefore, it presents a significant vulnerability in the clogs of tumors that could provide a wide window of therapeutic effectiveness. Natural compounds have been utilized extensively as successful interventions in the management of diverse chronic illnesses, including cancer. Owing to their capacity to influence multiple genes and pathways, natural compounds exhibit significant potential either as adjuvant therapy or in combination with conventional treatment options. In this review, we delineate the signaling nexus of YAP/TAZ axis, and present natural compounds as an alternate strategy to target cancer.

Natural product/diet-based regulation of macrophage polarization: Implications in treatment of inflammatory-related diseases and cancer

Macrophages are phagocytic cells with important physiological functions, including the digestion of cellular debris, foreign substances, and microbes, as well as tissue development and homeostasis. The tumor microenvironment (TME) shapes the aggressiveness of cancer, and the biological and cellular interactions in this complicated space can determine carcinogenesis. TME can determine the progression, biological behavior, and therapy resistance of human cancers. The macrophages are among the most abundant cells in the TME, and their functions and secretions can determine tumor progression. The education of macrophages to M2 polarization can accelerate cancer progression, and therefore, the re-education and reprogramming of these cells is promising. Moreover, macrophages can cause inflammation in aggravating pathological events, including cardiovascular diseases, diabetes, and neurological disorders. The natural products are pleiotropic and broad-spectrum functional compounds that have been deployed as ideal alternatives to conventional drugs in the treatment of cancer. The biological and cellular interactions in the TME can be regulated by natural products, and for this purpose, they enhance the M1 polarization of macrophages, and in addition to inhibiting proliferation and invasion, they impair the chemoresistance. Moreover, since macrophages and changes in the molecular pathways in these cells can cause inflammation, the natural products impair the pro-inflammatory function of macrophages to prevent the pathogenesis and progression of diseases. Even a reduction in macrophage-mediated inflammation can prevent organ fibrosis. Therefore, natural product-mediated macrophage targeting can alleviate both cancerous and non-cancerous diseases.

Heterologous expression of taxane genes confers resistance to fall armyworm in Nicotiana benthamiana

KEY MESSAGE

Taxadiene synthase, taxadiene-5α-hydroxylase, and taxane 13α-hydroxylase genes were introduced into Nicotiana benthamiana, and the improved resistance to lepidoptera pest fall armyworm was reported. Fall armyworm (FAW) is a serious agricultural pest. Genetic engineering techniques have been used to create pest-resistant plant varieties for reducing pest damage. Paclitaxel is a diterpenoid natural metabolite with antineoplastic effects in medicine. However, the effects of taxanes on the growth and development of lepidoptera pests, such as the FAW, are unknown. Here, selected paclitaxel precursor biosynthesis pathway genes, taxadiene synthase, taxane 5α-hydroxylase, and taxane 13α-hydroxylase, were engineered in the heterologous host Nicotiana benthamiana plants. Bioassay experiments showed that the transgenic N. benthamiana plants displayed improved resistance to FAW infestation, with degeneration of gut tissues and induced expression of apoptosis-related genes. Cytotoxicity experiment showed that the paclitaxel precursor, 10-deacetylbaccatin III, is cytotoxic to Sf9 cells, causing cell cycle arrest at the G2/M phase and disorder of the cytoskeleton. Metabolome analysis showed that heterologous expression of taxane genes in N. benthamiana affected the digestive system, steroid hormone and purine metabolism pathways of FAW larvae. In summary, this study provides a candidate approach for FAW control.

Cepharanthine analogs mining and genomes of Stephania accelerate anti-coronavirus drug discovery

Cepharanthine is a secondary metabolite isolated from Stephania. It has been reported that it has anti-conronaviruses activities including severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Here, we assemble three Stephania genomes (S. japonica, S. yunnanensis, and S. cepharantha), propose the cepharanthine biosynthetic pathway, and assess the antiviral potential of compounds involved in the pathway. Among the three genomes, S. japonica has a near telomere-to-telomere assembly with one remaining gap, and S. cepharantha and S. yunnanensis have chromosome-level assemblies. Following by biosynthetic gene mining and metabolomics analysis, we identify seven cepharanthine analogs that have broad-spectrum anti-coronavirus activities, including SARS-CoV-2, Guangxi pangolin-CoV (GX_P2V), swine acute diarrhoea syndrome coronavirus (SADS-CoV), and porcine epidemic diarrhea virus (PEDV). We also show that two other genera, Nelumbo and Thalictrum, can produce cepharanthine analogs, and thus have the potential for antiviral compound discovery. Results generated from this study could accelerate broad-spectrum anti-coronavirus drug discovery.

Berries vs. Disease: Revenge of the Phytochemicals

Secondary metabolites and phytochemicals in plant-based diets are known to possess properties that inhibit the development of several diseases including a variety of cancers of the aerodigestive tract. Berries are currently of high interest to researchers due to their high dietary source of phytochemicals. Black raspberries (BRB), Rubus occidentalis, are of special interest due to their rich and diverse composition of phytochemicals. In this review, we present the most up-to-date preclinical and clinical data involving berries and their phytochemicals in the chemoprevention of a variety of cancers and diseases. BRBs possess a variety of health benefits including anti-proliferative properties, anti-inflammatory activity, activation of pro-cell-death pathways, modulation of the immune response, microbiome modulation, reduction in oxidative stress, and many more. However, little has been done in both preclinical and clinical settings on the effects of BRB administration in combination with other cancer therapies currently available for patients. With the high potential for BRBs as chemopreventive agents, there is a need to investigate their potential in combination with other treatments to improve therapeutic efficacy.

Multivariate Analysis Compares and Evaluates Heat Tolerance of Potato Germplasm

High temperature is the most important environmental factor limiting potato (Solanum tuberosum L.) yield. The tuber yield has been used to evaluate the heat tolerance of some potato cultivars, but potato yield was closely correlated with the maturation period. Therefore, it is necessary to employ different parameters to comprehensively analyze and evaluate potato tolerance to heat stress. This study aimed to investigate physiologic changes during growth and development, and develop accurate heat tolerance evaluation methods of potato cultivars under heat stress. About 93 cultivars (including foreign elite lines, local landraces and cultivars) were screened using an in vitro tuber-inducing system (continuous darkness and 8% sucrose in the culture medium) under heat stress (30 °C) and normal (22 °C) conditions for 30 days. The tuber yield and number decreased significantly under heat stress compared to the control. A total of 42 cultivars were initially selected depending on tuber formation, after in vitro screening, further testing of selected cultivars was conducted in ex vitro conditions. The screened cultivars were further exposed to heat stress (35 °C/28 °C, day/night) for 60 days. Heat stress led to an increase in the plant height growth rate, fourth internode growth rate, and membrane damage, and due to heat-induced damage to chloroplasts, decrease in chlorophyll biosynthesis and photosynthetic efficiency. Three principal components were extracted by principal component analysis. Correlation and regression analysis showed that heat tolerance is positively correlated with the plant height growth rate, fourth internode growth rate, the content of chlorophyll b, photosynthetic rate, stomatal conductance, transpiration rate, tuber number, and tuber yield, and negatively correlated with the cell membrane injury level. The nine traits are accurate and representative indicators for evaluating potato tolerance to heat stress and could determine a relatively high mean forecast accuracy of 100.0% for the comprehensive evaluation value. Through cluster analysis and screening, cultivar FA, D73, and C132 had the highest heat comprehensive evaluation value, which could be further selected as heat-resistant varieties. This study provides insights into the different physiological mechanisms and accurate evaluation methods of potato cultivars under heat stress, which could be valuable for further research and breeding.

Cytotoxic effect of Rotheca serrata on cancer cell lines MCF-7 and neuroblastoma SH-SY5Y

INTRODUCTION

Rotheca serrata (Lamiaceae), a highly medicinal plant is used as an antidote for snakebite and the plant possesses medicinal properties like hepatoprotective, antitussive, antioxidant, anticancer, neuro-protective, used in rheumatoid arthritis and is also a α-glucoside inhibitor. AIM OF THE STUDY: This work aimed to study the anticancerous effect of Rotheca serrata (root and leaf) on cancer cell lines MCF-7 (breast cancer cell line) and Neuroblastoma SH-SY5Y.

MATERIALS AND METHODS

This investigation was a preliminary one which supported the retrospective and safe use of plants as described in Ayurveda. Dulbecco's Modified Eagle Medium with High Glucose (DMEM-HG) for culturing MCF-7- Human Breast cancer cell line and Minimum essential Medium (MEM)+F12 medium for culturing SH-SY5Y- Homo sapiens bone marrow neuroblast were used. MTT assay measured the cell proliferation rate and conversely, when metabolic events lead to apoptosis or necrosis, the reduction in cell viability.

RESULTS

The results indicated that the Methanolic extract of Rotheca serrata (root and leaf) showed high anticancer activity. Different concentrations of plant extracts (25, 50, 100, 200, 400 µg/ml) were used to study the anticancerous activity, amongst which the significant results were obtained for 400 µg/ml concentration (both root & leaf). Effective anticancer activity against MCF - 7 breast cancer cells was shown in methanoilc extracts and were expressed as IC 50 values; in root (IC 50 value = 61.8259 ± 7.428 µg/ml) and in leaf (IC 50 value = 78.1497 ± 6.316 µg/ml). The MTT assay in case of neuroblastoma (SH-SY5Y) cell lines revealed that 400 µg/ml concentration of leaf methanolic extract showed effective inhibition of cancer cells with IC 50 value 37.8462 ± 2.957 µg/ml as compared to IC 50 value of root methanolic extract which was 57.0895 ± 2.351 µg/ml.

CONCLUSION

R. serrata possess anticancer activity against breast cancer cell line (MCF-7) and neuroblastoma (SH-SY 5Y) cell lines. This study may to design plant-based drugs without side effects. Dosage compensation for specific type of cancer needs to be monitored in patients with 1st stage.

A novel micellar carrier to reverse multidrug resistance of tumours: TPGS derivatives with end-grafted cholesterol

D-α-tocopherol polyethylene glycol succinate (TPGS) has good biocompatibility, low immunogenicity, prolonged circulation time, and it can reverse multidrug resistance of tumours. However, the micelle concentration (CMC) of TPGS is too high (0.2 mg/mL) to develop the formulation of the micelle. In this study, TPGS was modified with cholesterol to obtain a new carrier material, TPGS-CHMC. The CMC of TPGS-CHMC was 2 μg/mL, which was extremely lower than that of TPGS. Docetaxel (DTX)-loaded TPGS-CHMC micelles (TPGS-CHMC/DTX) exhibited an average size of approximately 13 nm, a zeta potential of approximately -4.66 mV, and high encapsulation efficiency (99.2 ± 0.6%). TPGS-CHMC reduced mitochondrial membrane potential and cell membrane fluidity in paclitaxel-resistant ovarian cancer cells (A2780/T). In vivo, DiR-loaded TPGS-CHMC micelles were selectively distributed in A2780/T tumour-bearing nude mice. In A2780/T tumour-bearing nude mice, TPGS-CHMC/DTX micelles displayed significantly higher anti-tumour activity and less toxicity than the free DTX solution. In summary, TPGS-CHMC has various advantages, and provides a new option for developing functional polymeric micelles.

Identification of a Family of Glycoside Derivatives Biologically Active against Acinetobacter baumannii and Other MDR Bacteria Using a QSPR Model

As the rate of discovery of new antibacterial compounds for multidrug-resistant bacteria is declining, there is an urge for the search for molecules that could revert this tendency. Acinetobacter baumannii has emerged as a highly virulent Gram-negative bacterium that has acquired multiple resistance mechanisms against antibiotics and is considered of critical priority. In this work, we developed a quantitative structure-property relationship (QSPR) model with 592 compounds for the identification of structural parameters related to their property as antibacterial agents against A. baumannii. QSPR mathematical validation (R2 = 70.27, RN = −0.008, a(R2) = 0.014, and δK = 0.021) and its prediction ability (Q2LMO = 67.89, Q2EXT = 67.75, a(Q2) = −0.068, δQ = 0.0, rm2¯ = 0.229, and Δrm2 = 0.522) were obtained with different statistical parameters; additional validation was done using three sets of external molecules (R2 = 72.89, 71.64 and 71.56). We used the QSPR model to perform a virtual screening on the BIOFACQUIM natural product database. From this screening, our model showed that molecules 32 to 35 and 54 to 68, isolated from different extracts of plants of the Ipomoea sp., are potential antibacterials against A. baumannii. Furthermore, biological assays showed that molecules 56 and 60 to 64 have a wide antibacterial activity against clinically isolated strains of A. baumannii, as well as other multidrug-resistant bacteria, including Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa. Finally, we propose 60 as a potential lead compound due to its broad-spectrum activity and its structural simplicity. Therefore, our QSPR model can be used as a tool for the investigation and search for new antibacterial compounds against A. baumannii.

Recent Advances in Natural Product-Based Hybrids as Anti-Cancer Agents

Cancer is one of the top leading causes of death worldwide. It is a heterogenous disease characterized by unregulated cell proliferation and invasiveness of abnormal cells. For the treatment of cancer, natural products have been widely used as a source of therapeutic ingredients since ancient times. Although natural compounds and their derivatives have demonstrated strong antitumor activity in many types of cancer, their poor pharmacokinetic properties, low cell selectivity, limited bioavailability and restricted efficacy against drug-resistant cancer cells hinder their wide clinical application. Conjugation of natural products with other bioactive molecules has given rise to a new field in drug discovery resulting to the development of novel, bifunctional and more potent drugs for cancer therapy to overcome the current drawbacks. This review discusses multiple categories of such bifunctional conjugates and highlights recent trends and advances in the development of natural product hybrids. Among them, ADCs, PDCs, ApDCs, PROTACs and AUTOTACs represent emerging therapeutic agents against cancer.

Phytochemical-loaded liposomes for anticancer therapy: an updated review

The major obstacles observed in current chemotherapy are severe adverse effects, narrow therapeutic indexes and multidrug resistance. Anticancer phytochemicals are extracted and purified from natural plants, providing alternative therapeutic approaches with recognized biomedical benefits. However, poor bioavailability, high dose requirements and non-specific targeting have made those molecules less effective. To tackle those issues, liposomal nanovesicles for phytochemical delivery are taken into consideration for improving the therapeutic effectiveness by increasing transportation across cell barriers and conferring attractive cancer-specific targeting capabilities. In the present review, the liposomal approaches of anticancer phytochemicals are discussed, and recent advances in these formulations applied to cancer phytotherapy are further reviewed by an informed approach.

TcMYB29a, an ABA-Responsive R2R3-MYB Transcriptional Factor, Upregulates Taxol Biosynthesis in Taxus chinensis

Paclitaxel (Taxol), a highly modified diterpene agent mainly obtained from Taxus species, is the most widely used anticancer drug. Abscisic acid (ABA) is a well-known stress hormone that plays important roles in the secondary metabolism of plants, and it can also induce the accumulation of taxol in Taxus cell suspension cultures. However, the mechanism behind the regulation of taxol biosynthesis by ABA remains largely unknown. In previous research, a R2R3 MYB transcription factor (TF) TcMYB29a was observed to show a significant correlation with taxol biosynthesis, indicative of its potential role in the taxol biosynthesis. In this study, the TcMYB29a encoded by its gene was further characterized. An expression pattern analysis revealed that TcMYB29a was highly expressed in the needles and roots. Overexpression of TcMYB29a in Taxus chinensis cell suspension cultures led to an increased accumulation of taxol, and upregulated expression of taxol-biosynthesis-related genes, including the taxadiene synthase (TS) gene, the taxane 5α-hydroxylase (T5OH) gene, and the 3'-N-debenzoyl-2'-deoxytaxol-N-benzoyltransferase (DBTNBT) gene as compared to the controls. Chromatin immunoprecipitation (ChIP) assays, yeast one-hybrid (Y1H) assays, electrophoretic mobility shift assays (EMSAs), and dual-luciferase reporter assays verified that TcMYB29a could bind and activate the promoter of TcT5OH. Promoter sequence analysis of TcMYB29a revealed that its promoter containing an AERB site from -313 to -319 was a crucial ABA-responsive element. Subsequently, the ABA treatment assay showed that TcMYB29a was strongly upregulated at 6 h after ABA pretreatment. Furthermore, TcMYB29a was strongly suppressed at 3 h after the methyl jasmonate (MeJA) treatment and was depressed to the platform at 12 h. Taken together, these results reveal that TcMYB29a is an activator that improves the accumulation of taxol in Taxus chinensis cells through an ABA-medicated signaling pathway which is different from JA-medicated signaling pathways for the accumulation of taxol. These findings provide new insights into the potential regulatory roles of MYBs on the expression of taxol biosynthetic genes in Taxus.

Production and Structural Diversification of Withanolides by Aeroponic Cultivation of Plants of Solanaceae: Cytotoxic and Other Withanolides from Aeroponically Grown Physalis coztomatl

Withanolides constitute one of the most interesting classes of natural products due to their diversity of structures and biological activities. Our recent studies on withanolides obtained from plants of Solanaceae including Withania somnifera and a number of Physalis species grown under environmentally controlled aeroponic conditions suggested that this technique is a convenient, reproducible, and superior method for their production and structural diversification. Investigation of aeroponically grown Physalis coztomatl afforded 29 withanolides compared to a total of 13 obtained previously from the wild-crafted plant and included 12 new withanolides, physacoztolides I−M (9–13), 15α-acetoxy-28-hydroxyphysachenolide C (14), 28-oxophysachenolide C (15), and 28-hydroxyphysachenolide C (16), 5α-chloro-6β-hydroxy-5,6-dihydrophysachenolide D (17), 15α-acetoxy-5α-chloro-6β-hydroxy-5,6-dihydrophysachenolide D (18), 28-hydroxy-5α-chloro-6β-hydroxy-5,6-dihydrophysachenolide D (19), physachenolide A-5-methyl ether (20), and 17 known withanolides 3–5, 8, and 21–33. The structures of 9–20 were elucidated by the analysis of their spectroscopic data and the known withanolides 3–5, 8, and 21–33 were identified by comparison of their spectroscopic data with those reported. Evaluation against a panel of prostate cancer (LNCaP, VCaP, DU-145, and PC-3) and renal carcinoma (ACHN) cell lines, and normal human foreskin fibroblast (WI-38) cells revealed that 8, 13, 15, and 17–19 had potent and selective activity for prostate cancer cell lines. Facile conversion of the 5,6-chlorohydrin 17 to its 5,6-epoxide 8 in cell culture medium used for the bioassay suggested that the cytotoxic activities observed for 17–19 may be due to in situ formation of their corresponding 5β,6β-epoxides, 8, 27, and 28.

Microbial Cell Factory of Baccatin III Preparation in Escherichia coli by Increasing DBAT Thermostability and in vivo Acetyl-CoA Supply

Given the rapid development of genome mining in this decade, the substrate channel of paclitaxel might be identified in the near future. A robust microbial cell factory with gene dbat, encoding a key rate-limiting enzyme 10-deacetylbaccatin III-10-O-transferase (DBAT) in paclitaxel biosynthesis to synthesize the precursor baccatin III, will lay out a promising foundation for paclitaxel de novo synthesis. Here, we integrated gene dbat into the wild-type Escherichia coli BW25113 to construct strain BWD01. Yet, it was relatively unstable in baccatin III synthesis. Mutant gene dbat S189V with improved thermostability was screened out from a semi-rational mutation library of DBAT. When it was over-expressed in an engineered strain N05 with improved acetyl-CoA generation, combined with carbon source optimization of fermentation engineering, the production level of baccatin III was significantly increased. Using this combination, integrated strain N05S01 with mutant dbat S189V achieved a 10.50-fold increase in baccatin III production compared with original strain BWD01. Our findings suggest that the combination of protein engineering and metabolic engineering will become a promising strategy for paclitaxel production.

Antimalarial Natural Products

Natural products have made a crucial and unique contribution to human health, and this is especially true in the case of malaria, where the natural products quinine and artemisinin and their derivatives and analogues, have saved millions of lives. The need for new drugs to treat malaria is still urgent, since the most dangerous malaria parasite, Plasmodium falciparum, has become resistant to quinine and most of its derivatives and is becoming resistant to artemisinin and its derivatives. This volume begins with a short history of malaria and follows this with a summary of its biology. It then traces the fascinating history of the discovery of quinine for malaria treatment and then describes quinine's biosynthesis, its mechanism of action, and its clinical use, concluding with a discussion of synthetic antimalarial agents based on quinine's structure. The volume then covers the discovery of artemisinin and its development as the source of the most effective current antimalarial drug, including summaries of its synthesis and biosynthesis, its mechanism of action, and its clinical use and resistance. A short discussion of other clinically used antimalarial natural products leads to a detailed treatment of other natural products with significant antiplasmodial activity, classified by compound type. Although the search for new antimalarial natural products from Nature's combinatorial library is challenging, it is very likely to yield new antimalarial drugs. The chapter thus ends by identifying over ten natural products with development potential as clinical antimalarial agents.

Boosting the Anticancer Activity of Aspergillus flavus "endophyte of Jojoba" Taxol via Conjugation with Gold Nanoparticles Mediated by γ-Irradiation

Taxol production by fungi is one of the promising alternative approaches, regarding to the natural and semisynthetic sources; however, the lower yield and rapid loss of Taxol productivity by fungi are the major challenges that halt their further industrial implementation. Thus, searching for fungal isolates with affordable Taxol-production stability, in addition to enhance its anticancer activity via conjugation with gold nanoparticles, is the main objectives of this study. Twenty-four endophytic fungal isolates were recovered from the barks, twigs, and leaves of jojoba plant, among these fungi, Aspergillus flavus MW485934.1 was the most potent Taxol producer (88.6 µg/l). The chemical identity of the extracted Taxol of A. flavus was verified by the TLC, HPLC, HNMR, and FTIR analyses. The yield of Taxol produced by A. flavus was optimized by the response surface methodology (RSM) using Plackett-Burman (PBD) and faced central composite designs (FCCD). The yield of Taxol by A. flavus was increased by about 3.2 folds comparing to the control cultures (from 96.5 into 302.7 µg/l). The highest Taxol yield by was obtained growing A. flavus on a modified malt extract medium (g/l) (malt extract 20.0, peptone 2.0, sucrose 20.0, soytone 2.0, cysteine 0.5, glutamine 0.5, and beef extract 1.0 adjusted to pH 6.0) and incubated at 30 °C for 16 days. From the FCCD design, the significant variables affecting Taxol production by A. flavus were cysteine, pH, and incubation time. Upon A. flavus γ-irradiation at 1.0 kGy, the Taxol yield was increased by about 1.25 fold (375.9 µg/l). To boost its anticancer activity, the purified Taxol was conjugated with gold nanoparticles (AuNPs) mediated by γ-rays irradiation (0.5 kGy), and the physicochemical properties of Taxol-AuNPs composite were evaluated by UV-Vis, DLS, XRD, and TEM analyses. The IC₅₀ values of the native-Taxol and Taxol-AuNPs conjugates towards HEPG-2 cells were 4.06 and 2.1 µg/ml, while the IC₅₀ values against MCF-7 were 6.07 and 3.3 µg/ml, respectively. Thus, the anticancer activity of Taxol-AuNPs composite was increased by 2 folds comparing to the native Taxol towards HEPG-2 and MCF-7 cell lines. Also, the antimicrobial activity of Taxol against the multidrug resistant bacteria was dramatically increased upon conjugation with AuNPs comparing to authentic AuNPs and Taxol, ensuring the higher solubility, targetability, and efficiency of Taxol upon AuNPs conjugation.

Undifferentiated In Vitro Cultured Actinidia deliciosa as Cell Factory for the Production of Quercetin Glycosides

Land plants produce a vast arsenal of specialized metabolites and many of them display interesting bioactivities in humans. Recently, flavonol quercetin gained great attention in the light of the COVID-19 pandemic because, in addition to the anti-inflammatory, antiviral and anti-cancer activity already described, it emerged as possible inhibitor of 3CLpro, the major protease of SARS-CoV-2 virus. Plant cell and tissue culture (PCTC) is an attractive platform for the biotechnological production of plant metabolites. This technology allows a large amount of water and agricultural land to be saved and, being free of contaminants in the process, it is suitable for scaling up the production in bioreactors. In a project aimed to generate and screen in vitro plant cells for the production of valuable specialized metabolites for commercial production, we generated various cell lines from Actinidia deliciosa (kiwi fruit tree) and Actinidia chinensis (gold kiwi fruit tree), that were able to produce relevant amounts of quercetin derivatives, mainly quercetin glycosides. Three cell lines from A. deliciosa were characterized by targeted and untargeted metabolomics. In standard growing conditions, they produce and accumulate up to 13.26 mg/100 g fresh weight (419.76 mg/100 g dry weight) of quercetin derivatives. To address future industrial applications, these cell lines should be entered into an acceleration program to further increase the amount of these metabolites by optimizing the culture conditions and elicitation.

The Research Progress of Taxol in Taxus

BACKGROUND

Taxus is a valuable woody species with important medicinal value. The bark of Taxus can produce taxol, a natural antineoplastic drug that is widely used in the treatment of breast, ovarian and lung cancers. However, the low content of taxol in the bark of Taxus can not meet the growing clinical demands, so the current research aims at finding ways to increase taxol production.

OBJECTIVE

In this review, the research progress of taxol including the factors affecting the taxol content, biosynthesis pathway of taxol, production of taxol in vitro and the application of multi-omics approaches in Taxus as well as future research prospects will be discussed.

RESULTS

The taxol content is not only dependent on the species, age and tissues but is also affected by light, moisture levels, temperature, soil fertility and microbes. Most of the enzymes in the taxol biosynthesis pathway have been identified and characterized. Total chemical synthesis, semi-synthesis, plant cell culture and biosynthesis in endophytic fungi have been explored to product taxol. Multi-omics have been used to study Taxus and taxol.

CONCLUSION

Further efforts in the identification of unknown enzymes in the taxol biosynthesis pathway, establishment of the genetic transformation system in Taxus and the regulatory mechanism of taxol biosynthesis and Taxus cell growth will play a significant role in improving the yield of taxol in Taxus cells and plants.

Production, bioprocess optimization and γ-irradiation of Penicillium polonicum, as a new Taxol producing endophyte from Ginko biloba

Twenty-eight fungal endophytes were recovered from the different parts of Ginkgo biloba and screened for their Taxol producing potency. Among these isolates, Penicillium polonicum AUMC14487 was reported as the potent Taxol producer (90.53 μg/l). The chemical identity of the extracted Taxol was verified from the TLC, HPLC, NMR, EDX, and FTIR analyses. The extracted Taxol displayed a strong antiproliferative activity against HEPG2 (IC₅₀ 4.06 μM) and MCF7 (IC₅₀ 6.07 μM). The yield of Taxol by P. polonicum was optimized by nutritional optimization with the Response Surface Methodology (RSM) using Plackett-Burman and Central Composite Designs. In addition to nutritional optimization, the effect of γ-irradiation of the spores of P. polonicum on its Taxol producing potency was evaluated. The yield of Taxol by P. polonicum was increased via nutritional optimization by response surface methodology with Plackett-Burman and FCCD designs, and γ-irradiation by about 4.5 folds, comparing to the control culture. The yield of Taxol was increased by about 1.2 folds (401.2 μg/l) by γ -irradiation of the isolates at 0.5-0.75 kGy, comparing to the control cultures (332.2 μg/l). The highest Taxol yield was obtained by growing P. polonicum on modified Czapek's- Dox medium (sucrose 40.0 g/l, malt extract 20.0 g/l, peptone 2.0 g/l, K₂PO₄ 2.0 g/l, KCl 1.0 g/l, NaNO₃ 2.0 g/l, MgSO₄. 5H₂O 1.0 g/l) of pH 7.0 at 30.0 °C for 7.0 days. From the FCCD design, sucrose, malt extract and incubation time being the highest significant variables medium components affecting the Taxol production by P. polonicum.

Biologically Significant and Recently Isolated Alkaloids from Endophytic Fungi

A selection of the established and recently characterized alkaloids from the exploration of plant- and some marine-associated endophytic fungi is reviewed, with reference to alkaloids of biological significance.

Using Micropropagation to Develop Medicinal Plants into Crops

Medicinal plants are still the major source of therapies for several illnesses and only part of the herbal products originates from cultivated biomass. Wild harvests represent the major supply for therapies, and such practices threaten species diversity as well as the quality and safety of the final products. This work intends to show the relevance of developing medicinal plants into crops and the use of micropropagation as technique to mass produce high-demand biomass, thus solving the supply issues of therapeutic natural substances. Herein, the review includes examples of in vitro procedures and their role in the crop development of pharmaceuticals, phytomedicinals, and functional foods. Additionally, it describes the production of high-yielding genotypes, uniform clones from highly heterozygous plants, and the identification of elite phenotypes using bioassays as a selection tool. Finally, we explore the significance of micropropagation techniques for the following: a) pharmaceutical crops for production of small therapeutic molecules (STM), b) phytomedicinal crops for production of standardized therapeutic natural products, and c) the micropropagation of plants for the production of large therapeutic molecules (LTM) including fructooligosaccharides classified as prebiotic and functional food crops.

Natural products in drug discovery: advances and opportunities

Natural products and their structural analogues have historically made a major contribution to pharmacotherapy, especially for cancer and infectious diseases. Nevertheless, natural products also present challenges for drug discovery, such as technical barriers to screening, isolation, characterization and optimization, which contributed to a decline in their pursuit by the pharmaceutical industry from the 1990s onwards. In recent years, several technological and scientific developments - including improved analytical tools, genome mining and engineering strategies, and microbial culturing advances - are addressing such challenges and opening up new opportunities. Consequently, interest in natural products as drug leads is being revitalized, particularly for tackling antimicrobial resistance. Here, we summarize recent technological developments that are enabling natural product-based drug discovery, highlight selected applications and discuss key opportunities.

Into the Fray! A Beginner's Guide to Medicinal Chemistry

Modern medicinal chemistry is a complex, multidimensional discipline that operates at the interface of the chemical and biological sciences. The medicinal chemistry contribution to drug discovery is typically described in the context of the well-recited linear progression of the drug discovery pipeline. However, compound optimization is idiosyncratic to each project, and clear definitions of hit and lead molecules and the subsequent progress along the pipeline becomes easily blurred. In addition, this description lacks insight into the entangled relationship between chemical and pharmacological properties, and thus provides limited guidance on how innovative medicinal chemistry strategies can be applied to solve optimization problems, regardless of the stage in the pipeline. Through discussion and illustrative examples, this article seeks to provide insights into the finesse of medicinal chemistry and the subtlety of balancing chemical properties pharmacology. In so doing, it aims to serve as an accessible and simple-to-digest guide for anyone who wishes to learn about the underlying principles of medicinal chemistry, in a context that has been decoupled from the pipeline description.

Whole fungal elicitors boost paclitaxel biosynthesis induction in Corylus avellana cell culture

Paclitaxel is an effective natural-source chemotherapeutic agent commonly applied to treat a vast range of cancers. In vitro Corylus avellana culture has been reported as a promising and inexpensive system for paclitaxel production. Fungal elicitors have been made known as the most efficient strategy for the biosynthesis induction of secondary metabolites in plant in vitro culture. In this research, C. avellana cell suspension culture (CSC) was exposed to cell extract (CE) and culture filtrate (CF) derived from Camarosporomyces flavigenus, either individually or combined treatment, in mid and late log phase. There is no report on the use of whole fungal elicitors (the combined treatment of CE and CF) for the elicitation of secondary metabolite biosynthesis in plant in vitro culture. The combined treatment of CE and CF significantly led to more paclitaxel biosynthesis and secretion than the individual use of them. Also, multivariate statistical approaches including stepwise regression (SR), ordinary least squares regression (OLSR), principal component regression (PCR) and partial least squares regression (PLSR) were used to model and predict paclitaxel biosynthesis and secretion. Based on value account for (VAF), root mean square error (RMSE), coefficient of determination (R²), mean absolute percentage error (MAPE) and relative percent difference (RPD) can be concluded that mentioned regression models effectively worked only for modeling and predicting extracellular paclitaxel portion in C. avellana cell culture.

Exploiting the Biosynthetic Potency of Taxol from Fungal Endophytes of Conifers Plants; Genome Mining and Metabolic Manipulation

Endophytic fungi have been considered as a repertoire for bioactive secondary metabolites with potential application in medicine, agriculture and food industry. The biosynthetic pathways by fungal endophytes raise the argument of acquisition of these machineries of such complex metabolites from the plant host. Diterpenoids "Taxol" is the most effective anticancer drug with highest annual sale, since its discovery in 1970 from the Pacific yew tree, Taxus brevifolia. However, the lower yield of Taxol from this natural source (bark of T. brevifolia), availability and vulnerability of this plant to unpredicted fluctuation with the ecological and environmental conditions are the challenges. Endophytic fungi from Taxus spp. opened a new avenue for industrial Taxol production due to their fast growth, cost effectiveness, independence on climatic changes, feasibility of genetic manipulation. However, the anticipation of endophytic fungi for industrial Taxol production has been challenged by the loss of its productivity, due to the metabolic reprograming of cells, downregulating the expression of its encoding genes with subculturing and storage. Thus, the objectives of this review were to (1) Nominate the endophytic fungal isolates with the Taxol producing potency from Taxaceae and Podocarpaceae; (2) Emphasize the different approaches such as molecular manipulation, cultural optimization, co-cultivation for enhancing the Taxol productivities; (3) Accentuate the genome mining of the rate-limiting enzymes for rapid screening the Taxol biosynthetic machinery; (4) Triggering the silenced rate-limiting genes and transcriptional factors to activates the biosynthetic gene cluster of Taxol.

Antioxidative, antimitotic, and DNA-damaging activities of Garcinia kola stem bark, Uvaria chamae root, and Olax subscorpioidea root used in the ethnotherapy of cancers

Garcinia kola (GK) stem bark, Uvaria chamae (UC) root, and Olax subscorpioidea (OS) root are components of various indigenous/traditional anticancer regimens. It is, therefore, possible that they might combat oxidative stress and impair cellular proliferation linked to carcinogenesis. In this study, we investigated the antioxidative, mito-depressive, and DNA-damaging activities of the three plant extracts in order to provide further mechanistic insights into their potential anticancer roles in documented cancer remedies that include them. Antioxidative properties were investigated in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide (NO) radical scavenging assays and an animal model of drug (cisplatin)-induced oxidative stress. The Allium cepa assay and the single cell gel electrophoresis (SCGE) assay were used to assess mito-depressive and DNA-damaging activities. GK and OS showed significantly higher antioxidant activities in the DPPH assay than ascorbic acid; OS had the lowest IC50 of the three plants in the NO assay, comparable to that of ascorbic acid. Pretreatment with the extracts produced an ameliorative and protective effect against the cisplatin-induced oxidative stress as shown by inhibition of lipid peroxidation and improved or restored reduced glutathione and superoxide dismutase levels. In the Allium test, the three extracts produced significant decreases in root growth and also significant cytotoxicity as evidenced by decreased mitotic index. Each of the extracts also showed significantly increased tail DNA (%) in the SCGE assay, indicating the significant DNA-damaging effect. Taken together, this study demonstrates the possible chemopreventive and chemotherapeutic potentials of the three study extracts, which may explain the roles of their source plants in traditional remedies in the therapy of cancers.

Fungal Cell Wall and Methyl-β-Cyclodextrin Synergistically Enhance Paclitaxel Biosynthesis and Secretion in Corylus avellana Cell Suspension Culture

Paclitaxel is the top-selling chemotherapeutic drug used for the treatment of lung, ovarian and breast cancer as well as Kaposi's sarcoma. Cell suspension culture (CSC) of Corylus avellana has been addressed as a promising alternative for producing paclitaxel. In this study, endophytic fungus strain YEF33 was isolated from Taxus baccata and identified as Coniothyrium palmarum. The effects of the elicitors derived from this fungus including cell extract, culture filtrate and cell wall (CW) and also chitin, alone or in combination with Methyl-β-Cyclodextrin (MBCD), on paclitaxel biosynthesis in C. avellana CSC were assayed for the first time. CW of C. palmarum was the most efficient fungal elicitor for paclitaxel biosynthesis in C. avellana CSC. The results revealed that MBCD affected paclitaxel biosynthesis differently depending on fungal elicitor type and vice versa. MBCD, either alone or in combination with fungal elicitors, induced a high secretion of paclitaxel, suggesting the decrement of toxicity and retro-inhibition processes of paclitaxel for cells. The joint effects of C. palmarum CW (2.5% (v/v) on 17th day) and 50 mM MBCD synergistically enhanced paclitaxel biosynthesis (402.4 µg l-1; 5.8-fold), 78.6% of which (316.5 µg l-1) were secreted into culture medium, a level 146% higher than that in control.

High-effective biosynthesis of baccatin Ⅲ by using the alternative acetyl substrate, N-acetyl-d-glucosamine

AIMS

Paclitaxel is a type of broad-spectrum anticancer drug in short supply. The price of acetyl-CoA (17 709 677·4 USD mol^-1 ), which is the acetyl group donor for the enzymatic synthesis of the intermediate, baccatin Ⅲ, is still the bottleneck of the mass production of paclitaxel. This study reports a novel acetyl group donor, which could substantially reduce the cost of production.

METHODS AND RESULTS

In this study, a substrate spectrum with 14 kinds of representative acetyl-donor substitutes predicted by computer-aided methods was tested in a 10-deacetylbaccatin Ⅲ-10-O-acetyltransferase (DBAT) heterogeneous-expressed open-whole-cell catalytic system. The results of computer prediction and experimental analysis revealed the rule of the acetyl-donor compounds based on this substrate spectrum. N-acetyl-d-glucosamine (30·95 USD mol^-1 , about 572 202-fold cheaper than acetyl-CoA) is selected as a suitable substitute under the rule. The yield when using N-acetyl-d-glucosamine as acetyl donor in open-whole-cell catalytic system was 2·13-fold of that when using acetyl-CoA. In the in vivo system, the yield increased 24·17%, which may indicate its cooperation with acetyl-CoA.

CONCLUSION

The success of open-whole-cell synthesis and in vivo synthesis of baccatin Ⅲ by adding N-acetyl-d-glucosamine as acetyl substrate demonstrates that it is a useful substrate to improve the yield of baccatin Ⅲ.

SIGNIFICANCE AND IMPACT OF THE STUDY

All these findings provided a potential acetyl-donor substitute for acetyl-CoA, as well as a low cost and efficient method of preparing paclitaxel through baccatin Ⅲ semi-synthesis.

The R2R3-MYB transcription factor family in Taxus chinensis: identification, characterization, expression profiling and posttranscriptional regulation analysis

The MYB transcription factor family is one of the largest gene families playing regulatory roles in plant growth and development. The MYB family has been studied in a variety of plant species but has not been reported in Taxus chinensis. Here we identified 72 putative R2R3-MYB genes in T. chinensis using a comprehensive analysis. Sequence features, conversed domains and motifs were characterized. The phylogenetic analysis showed TcMYBs and AtMYBs were clustered into 36 subgroups, of which 24 subgroups included members from T. chinensis and Arabidopsis thaliana, while 12 subgroups were specific to one species. This suggests the conservation and specificity in structure and function of plant R2R3-MYBs. The expression of TcMYBs in various tissues and different ages of xylem were investigated. Additionally, miRNA-mediated posttranscriptional regulation analysis revealed that TcMYBs were the targets of miR858, miR159 and miR828, suggesting the posttranscriptional regulation of MYBs is highly conserved in plants. The results provide a basis for further study the role of TcMYBs in the regulation of secondary metabolites of T. chinensis.

Innovative Approaches for Recovery of Phytoconstituents from Medicinal/Aromatic Plants and Biotechnological Production

Continuously growing demand for plant derived therapeutic molecules obtained in a sustainable and eco-friendly manner favors biotechnological production and development of innovative extraction techniques to obtain phytoconstituents. What is more, improving and optimization of alternative techniques for the isolation of high value natural compounds are issues having both social and economic importance. In this critical review, the aspects regarding plant biotechnology and green downstream processing, leading to the production and extraction of increased levels of fine chemicals from both plant cell, tissue, and organ culture or fresh plant materials and the remaining by-products, are discussed.

A comparative metabolomics analysis of the components of heartwood and sapwood in Taxus chinensis (Pilger) Rehd

Taxus chinensis is a well-known gymnosperm with great ornamental and medicinal value. Its purple red brown heartwood (HW) has many attributes such as straight texture, high density, mechanical strength, rich elasticity and corrosion resistance that is highly prized commercially. T. chinensis sapwood (SW), in comparison, lacks these important traits. At present, little is known about the differences of metabolites between the SW and HW in T. chinensis. Widely targeted metabolic profiling was performed to analyze the metabolic profiles of HW and SW in T. chinensis using Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (LC-EI-MS). A total of 607 metabolites were detected in HW and SW. Among them, 146 metabolites were significantly higher, and 167 metabolites significantly lower, in HW as compared to SW. These differential metabolites were mainly involved in metabolic pathways and biosynthesis of secondary metabolites, such as flavonoids, flavone and flavonol, phenylpropanoids and antibiotics. Moreover, 71 flavonoids and isoflavones were found to be significantly different between HW and SW. Our results show the difference of components between the HW and SW, which has potential significance to further elucidate the mechanism of HW color formation. The results will provide insight into the metabolites associated with wood color formation and useful information for understanding the metabolites associated with wood quality.

Engineered Production of Hapalindole Alkaloids in the Cyanobacterium Synechococcus sp. UTEX 2973

Cyanobacteria produce numerous valuable bioactive secondary metabolites (natural products) including alkaloids, isoprenoids, nonribosomal peptides, and polyketides. However, the genomic organization of the biosynthetic gene clusters, complex gene expression patterns, and low compound yields synthesized by the native producers currently limits access to the vast majority of these valuable molecules for detailed studies. Molecular cloning and expression of such clusters in heterotrophic hosts is often precarious owing to genetic and biochemical incompatibilities. Production of such biomolecules in photoautotrophic hosts analogous to the native producers is an attractive alternative that has been under-explored. Here, we describe engineering of the fast-growing cyanobacterium Synechococcus elongatus UTEX 2973 to produce key compounds of the hapalindole family of indole-isonitrile alkaloids. Engineering of the 42-kbp "fam" hapalindole pathway from the cyanobacterium Fischerella ambigua UTEX 1903 into S2973 was accomplished by rationally reconstructing six to seven core biosynthetic genes into synthetic operons. The resulting Synechococcus strains afforded controllable production of indole-isonitrile biosynthetic intermediates and hapalindoles H and 12-epi-hapalindole U at a titer of 0.75-3 mg/L. Exchanging genes encoding fam cyclase enzymes in the synthetic operons was employed to control the stereochemistry of the resulting product. Establishing a robust expression system provides a facile route to scalable levels of similar natural and new forms of bioactive hapalindole derivatives and its structural relatives (e.g., fischerindoles, welwitindolinones). Moreover, this versatile expression system represents a promising tool for exploring other functional characteristics of orphan gene products that mediate the remarkable biosynthesis of this important family of natural products.

Stylosin and some of its synthetic derivatives induce apoptosis in prostate cancer cells as 15-lipoxygenase enzyme inhibitors

Overexpression of 15-lipoxygenase-1 (15-LOX-1) enzyme has been reported in prostate tumors, and its expression levels are associated with the degree of cancer malignancy. The aim of this study was to investigate inhibitory effects of stylosin and some similar synthetic monoterpenoids on 15-LOX and also their cytotoxic and anti-cancer activities on prostate cancer cells. Cytotoxicity of compounds was evaluated on prostate cancer cell line "PC-3" and normal human fibroblast "HFF3" cells using AlamarBlue reduction test. The inhibitory effects of the compounds against soybean 15-LOX, a commercially available enzyme, were also assessed. Finally, mechanism of cell death was investigated by flow cytometry. Some of these terpenoids had cytotoxic effects on PC-3 cells, and strong positive correlation was observed between the 15-LOX-1 inhibition potential and the cytotoxicity of the compounds. Moreover, flow cytometry results indicated that apoptosis was the predominant mechanism of induced cell death, which emphasizes the potential of these compounds in prostate cancer therapy. Among studied terpenoids, "fenchyl ferulate" exhibited about three times more cytotoxicity than cisplatin. Strong positive correlation observed between 15-LOX inhibition potential and cytotoxicity of the compounds indicates selective anti-cancer properties of the compounds might be exerted via inhibition of 15-LOX-1 in PC-3 cells. Furthermore, observed cytotoxicity is mediated through apoptosis, which is probably triggered via 15-LOX-1 inhibition.

Adverse drug reactions of anticancer drugs derived from natural sources

Cancer, a life threatening disease adversely affects huge population worldwide. Naturally derived drug discovery has emerged as a potential pathway in search of anticancers. Natural products-based drugs are generally considered safe, compared to their synthetic counterparts. A systematic review on adverse drugs reactions (ADRs) of the anticancer natural products has not been performed till date. We reviewed anticancer drugs, derived from plants, microbes and marine sources with their mechanistic action and reported ADRs. PubMed, ScienceDirect and Scopus were searched through Boolean information retrieval method using keywords "natural products", "cancer", "herbal", "marine drugs" and "adverse drug reaction". We documented ADRs of natural products based anticancer agents, mechanisms of action and chemical structures. It was observed that majority of the natural products based anticancer drugs possess ample adverse effects, dominantly hematological toxicities, alopecia, neurotoxicity and cardiotoxicity. These findings deviate from the preconceived notion about safer nature of herbal drugs. We also came across some anti-cancer natural products with less/no reported adverse events like Cabazitaxel and Arglabin. Comprehensive pharmacovigilance studies are needed to report ADRs and thereby predicting safety of anti-cancer drugs, either originated from natural sources or chemically synthesized.

Identification of rate-limiting enzymes involved in paclitaxel biosynthesis pathway affected by coronatine and methyl-β-cyclodextrin in Taxus baccata L. cell suspension cultures

Background

Paclitaxel is a potent antitumor alkaloid widely used for the treatment of several cancer types. This valuable secondary metabolite naturally exists in the inner bark of Taxus species in very low amounts. The small-scale production of paclitaxel in Taxus cell cultures requires utilization of several elicitors.

Objective

The main objective of this work was to identify key genes that encode rate-limiting enzymes in paclitaxel biosynthesis pathway by investigating the possible relationship between paclitaxel production and a set of 13 involved genes’ relative expression in Taxus baccata L. cell suspension cultures affected by coronatine and methyl-β-cyclodextrin.

Methods

In the present research, the most important key genes were identified using gene expression profiling evaluation and paclitaxel production assessment in Taxus baccata L. cell cultures affected by mentioned elicitors.

Results and Conclusion

Gene expression levels were variably increased using methyl-β-cyclodextrin, and in some cases, a synergistic effect on transcript accumulation was observed when culture medium was supplemented with both elicitors. It was revealed that DBAT, BAPT, and DBTNBT are the most important rate-limiting enzymes in paclitaxel biosynthesis pathway in Taxus baccata L. cell suspension cultures under coronatine and methyl-β-cyclodextrin elicitation condition. Moreover, PAM was identified as one of the important key genes especially in the absence of β-phenylalanine. In cell cultures affected by these elicitors, paclitaxel was found largely in the culture media (more than 90%). The secretion of this secondary metabolite suggests a limited feedback inhibition and reduced paclitaxel toxicity for producer cells. It is the result of the ABC gene relative expression level increment under methyl-β-cyclodextrin elicitation and highly depends on methyl-β-cyclodextrin’s special property (complex formation with hydrophobic compounds). Paclitaxel biosynthesis was obviously increased due to the effect of coronatine and methyl-β-cyclodextrin elicitation, leading to the production level of 5.62 times higher than that of the untreated cultures.

Graphical abstract

Elicitors Derived from Hazel (Corylus avellana L.) Cell Suspension Culture Enhance Growth and Paclitaxel Production of Epicoccum nigrum

The microbial fermentation is considered as the potential source for large-scale production of paclitaxel. Since co-cultivation/mixed fermentation strategy has been reported as a yield enhancement strategy for paclitaxel production, investigation of fungal endophyte response to plant culture medium, plant cell extract (CE) and medium filtrate (MF) of plant cell suspension culture in terms of growth and paclitaxel production is interesting. In this study, 35 endophytic fungi were isolated from Taxus baccata and Corylus avellana grown in Iran. The analysis of high-performance liquid chromatography and mass spectrometry showed that one isolate (YEF2) produced paclitaxel. The isolate YEF2 was identified as Epicoccum nigrum by sequencing of ITS1-5.8S-ITS2 rDNA region and actin gene. YEF2 was slow-growing in Murashige and Skoog medium, but the synergistic interaction of gibberellic acid (GA3) and CE of C. avellana enhanced the growth of YEF2. The highest total yield of paclitaxel (314.7 µg/l; 11.5-folds) of E. nigrum strain YEF2 was obtained by using 28% (v/v) filter sterilized CE of C. avellana and 2 µg ml-1 GA3 that was significantly higher than the control. In this study, the effects of the plant cell extract on growth and paclitaxel production of paclitaxel producing endophytic fungus were studied for the first time.

Traditional treatment of human and animal salmonelloses in Southern Benin: Knowledge of farmers and traditherapists

AIM

This study aimed to report medicinal plants that are likely to be used in the control of salmonellosis.

MATERIALS AND METHODS

A cross-sectional study was conducted in Southern Benin. Semi-structured questionnaires were administered to 150 farmers and 100 traditional therapists in seven high municipalities. This step helped to collect plants that are used in the treatment of animal salmonellosis and typhoid fever in human.

RESULTS

The results revealed a low level of use of medicinal plants among breeders who prefer antibiotics such as oxytetracycline (53.55%), tylosine + sulfadimerazine (15.30%), and alphaceryl (19.13%). However, plants such as Moringa oleifera (leaves), Carica papaya (leaves and seeds), and Vernonia amygdalina (leaves) were mostly used by some farmers. From traditional therapists, 57 plant species of 32 families were identified as typhoid fever cures; among which Leguminosae, Asteraceae, and Euphorbiaceae were predominant. Persea americana (22.72%), V. amygdalina (7.57%), and Corchorus olitorius (7.57%) were the most cited by traditherapists for the treatment of typhoid fever in human.

CONCLUSION

This study provides a database for further studies on the in vitro and in vivo efficacy of Benin plant species on Salmonellaspp. These evaluations will guarantee the availability of new therapeutic solutions for populations.

Transcriptome Assembly and Systematic Identification of Novel Cytochrome P450s in Taxus chinensis

Taxus spp. is a highly valuable medicinal plant with multiple pharmacological effects on various cancers. Cytochrome P450s (CYP450s) play important roles in the biosynthesis of active compounds in Taxus spp., such as the famous diterpenoid, Taxol. However, some specific CYP450 enzymes involved in the biosynthesis of Taxol remain unknown, and the systematic identification of CYP450s in Taxus has not been reported. In this study, 118 full-length and 175 partial CYP450 genes were identified in Taxus chinensis transcriptomes. The 118 full-length genes were divided into 8 clans and 29 families. The CYP71 clan included all A-type genes (52) belonging to 11 families. The other seven clans possessed 18 families containing 66 non-A-type genes. Two new gymnosperm-specific families were discovered, and were named CYP864 and CYP947 respectively. Protein sequence alignments revealed that all of the T. chinensis CYP450s hold distinct conserved domains. The expression patterns of all 118 CYP450 genes during the long-time subculture and MeJA elicitation were analyzed. Additionally, the expression levels of 15 novel CYP725 genes in different Taxus species were explored. Considering all the evidence, 6 CYP725s were identified to be candidates for Taxol biosynthesis. The cis-regulatory elements involved in the transcriptional regulation were also identified in the promoter regions of CYP725s. This study presents a comprehensive overview of the CYP450 gene family in T. chinensis and can provide important insights into the functional gene studies of Taxol biosynthesis.

Three indigenous plants used in anti-cancer remedies, Garcinia kola Heckel (stem bark), Uvaria chamae P. Beauv. (root) and Olax subscorpioidea Oliv. (root) show analgesic and anti-inflammatory activities in animal models

ETHNOPHARMACOLOGICAL RELEVANCE

Phytochemicals with anti-oxidative and anti-inflammatory properties are known to inhibit tumour initiation, promotion and progression. Hence, there is an increasingly-convincing rationale for employing remedies containing those phytochemicals in the treatment of cancers and also as analgesic and anti-inflammatory adjuvants in therapy. The plants Garcinia kola Heckel (Clusiaceae), stem bark; Uvaria chamae P. Beauv. (Annonaceae), root; and Olax subscorpioidea Oliv. (Olacaceae), root, have been documented to be part of various indigenous anti-cancer regimens.

AIM OF THE STUDY

To determine if the three plants exhibit significant anti-oxidative and anti-inflammatory properties.

MATERIALS AND METHODS

Using established models, the analgesic and anti-inflammatory activities of the three plants were investigated.

RESULTS

Pre-treatment with the plant extracts at 100, 200 and 400mg/kg produced inhibition of writhes; G. kola and U. chamae showed no significant effect on formalin-induced pain, but O. subscorpioidea produced inhibition in both phases of the formalin test. Similarly, while G. kola and U. chamae did not produce any significant inhibitory effect in the xylene-induced ear oedema model, the oedema was significantly reduced by O. subscorpioidea pre-treatment. However, all the three plants significantly inhibited the time-dependent increase in paw circumference in the carrageenan- and formaldehyde-induced rat paw oedema tests, with peak effects observed at 400mg/kg, 6h after the induction of oedema, comparable in some cases to the effects of two standard drugs, the non-steroidal anti-inflammatory drug diclofenac and the anti-inflammatory antibiotic doxycycline.

CONCLUSION

We conclude that the three plant extracts possess analgesic and anti-inflammatory properties, thus providing a scientific rationale for their inclusion in some traditional anti-cancer regimens.

Plant cytochrome P450s: nomenclature and involvement in natural product biosynthesis

Cytochrome P450s constitute the largest family of enzymatic proteins in plants acting on various endogenous and xenobiotic molecules. They are monooxygenases that insert one oxygen atom into inert hydrophobic molecules to make them more reactive and hydro-soluble. Besides for physiological functions, the extremely versatile cytochrome P450 biocatalysts are highly demanded in the fields of biotechnology, medicine, and phytoremediation. The nature of reactions catalyzed by P450s is irreversible, which makes these enzymes attractions in the evolution of plant metabolic pathways. P450s are prime targets in metabolic engineering approaches for improving plant defense against insects and pathogens and for production of secondary metabolites such as the anti-neoplastic drugs taxol or indole alkaloids. The emerging examples of P450 involvement in natural product synthesis in traditional medicinal plant species are becoming increasingly interesting, as they provide new alternatives to modern medicines. In view of the divergent roles of P450s, we review their classification and nomenclature, functions and evolution, role in biosynthesis of secondary metabolites, and use as tools in pharmacology.

Discovery and resupply of pharmacologically active plant-derived natural products: A review

Medicinal plants have historically proven their value as a source of molecules with therapeutic potential, and nowadays still represent an important pool for the identification of novel drug leads. In the past decades, pharmaceutical industry focused mainly on libraries of synthetic compounds as drug discovery source. They are comparably easy to produce and resupply, and demonstrate good compatibility with established high throughput screening (HTS) platforms. However, at the same time there has been a declining trend in the number of new drugs reaching the market, raising renewed scientific interest in drug discovery from natural sources, despite of its known challenges. In this survey, a brief outline of historical development is provided together with a comprehensive overview of used approaches and recent developments relevant to plant-derived natural product drug discovery. Associated challenges and major strengths of natural product-based drug discovery are critically discussed. A snapshot of the advanced plant-derived natural products that are currently in actively recruiting clinical trials is also presented. Importantly, the transition of a natural compound from a "screening hit" through a "drug lead" to a "marketed drug" is associated with increasingly challenging demands for compound amount, which often cannot be met by re-isolation from the respective plant sources. In this regard, existing alternatives for resupply are also discussed, including different biotechnology approaches and total organic synthesis. While the intrinsic complexity of natural product-based drug discovery necessitates highly integrated interdisciplinary approaches, the reviewed scientific developments, recent technological advances, and research trends clearly indicate that natural products will be among the most important sources of new drugs also in the future.

Metabolic engineering of Nicotiana benthamiana for the increased production of taxadiene

We report the production of taxadiene by transformation of N. benthamiana with a taxadiene synthase gene. The production was significantly increased by an elicitor treatment or metabolic pathway shunting. Paclitaxel (Taxol(®)) was first isolated from the bark of the pacific yew tree as an anticancer agent and has been used extensively to treat various types of cancer. Taxadiene, the first committed product of paclitaxel synthesis is cyclized from geranylgeranyl diphosphate (GGPP), and further complex hydroxylation and acylation processes of the unique taxane core skeleton produce paclitaxel. To accomplish de novo production of taxadiene, we transformed Nicotiana benthamiana with a taxadiene synthase (TS) gene. The introduced TS gene under the transcriptional control of the CaMV 35S promoter was constitutively expressed in N. benthamiana, and the de novo production of taxadiene was confirmed by mass spectroscopy profiling. Transformed N. benthamiana homozygous lines produced 11-27 μg taxadiene/g of dry weight. The highest taxadiene production line TSS-8 was further treated with an elicitor, methyl jasmonate, and metabolic pathway shunting by suppression of the phytoene synthase gene expression which resulted in accumulation of increased taxadiene accumulation by 1.4- or 1.9-fold, respectively. In summary, we report that the production of taxadiene in N. benthamiana was possible by the ectopic expression of the TS gene, and higher accumulation of taxadiene could be achieved by elicitor treatment or metabolic pathway shunting of the terpenoid pathway.

Genome sequencing and analysis of the paclitaxel-producing endophytic fungus Penicillium aurantiogriseum NRRL 62431

Background

Paclitaxel (Taxol™) is an important anticancer drug with a unique mode of action. The biosynthesis of paclitaxel had been considered restricted to the Taxus species until it was discovered in Taxomyces andreanae, an endophytic fungus of T. brevifolia. Subsequently, paclitaxel was found in hazel (Corylus avellana L.) and in several other endophytic fungi. The distribution of paclitaxel in plants and endophytic fungi and the reported sequence homology of key genes in paclitaxel biosynthesis between plant and fungi species raises the question about whether the origin of this pathway in these two physically associated groups could have been facilitated by horizontal gene transfer.

Results

The ability of the endophytic fungus of hazel Penicillium aurantiogriseum NRRL 62431 to independently synthesize paclitaxel was established by liquid chromatography-mass spectrometry and proton nuclear magnetic resonance. The genome of Penicillium aurantiogriseum NRRL 62431 was sequenced and gene candidates that may be involved in paclitaxel biosynthesis were identified by comparison with the 13 known paclitaxel biosynthetic genes in Taxus. We found that paclitaxel biosynthetic gene candidates in P. aurantiogriseum NRRL 62431 have evolved independently and that horizontal gene transfer between this endophytic fungus and its plant host is unlikely.

Conclusions

Our findings shed new light on how paclitaxel-producing endophytic fungi synthesize paclitaxel, and will facilitate metabolic engineering for the industrial production of paclitaxel from fungi.