Production of adventitious root biomass and secondary metabolites of Hypericum perforatum L. in a balloon type airlift reactor

Bioreactor configurations for adventitious root culture: recent advances toward the commercial production of specialized metabolites

In vitro plant cell and organ cultures are appealing alternatives to traditional methods of producing valuable specialized metabolites for use as: pharmaceuticals, food additives, cosmetics, perfumes, and agricultural chemicals. Cell cultures have been adopted for the production of specialized metabolites in certain plants. However, in certain other systems, adventitious roots are superior to cell suspension cultures as they are organized structures that accumulate high levels of specialized metabolites. The cultivation of adventitious roots has been investigated in various bioreactor systems, including: mechanically agitated, pneumatically agitated, and modified bioreactors. The main relevance and importance of this work are to develop a long-lasting industrial biotechnological technology as well as to improve the synthesis of these metabolites from the plant in vitro systems. These challenges are exacerbated by: the peculiarities of plant cell metabolism, the complexity of specialized metabolite pathways, the proper selection of bioreactor systems, and bioprocess optimization. This review's major objective is to analyze several bioreactor types for the development of adventitious roots, as well as the advantages and disadvantages of each type of bioreactor, and to describe the strategies used to increase the synthesis of specialized metabolites. This review also emphasizes current advancements in the field, and successful instances of scaled-up cultures and the generation of specialized metabolites for commercial purposes are also covered.

Different Types of Hypericum perforatum cvs. (Elixir, Helos, Topas) In Vitro Cultures: A Rich Source of Bioactive Metabolites and Biological Activities of Biomass Extracts

Microshoot agitated and bioreactor cultures (PlantForm bioreactors) of three Hypericum perforatum cultivars (Elixir, Helos, Topas) were maintained in four variants of Murashige and Skoog medium (MS) supplemented with 6-benzylaminopurine (BAP) and 1-naphthaleneacetic acid (NAA) (in the range of 0.1-3.0 mg/L). In both types of in vitro cultures, the accumulation dynamics of phenolic acids, flavonoids, and catechins were investigated during 5- and 4-week growth cycles, respectively. The contents of metabolites in methanolic extracts from biomasses collected in 1-week intervals were estimated by HPLC. The highest total contents of phenolic acids, flavonoids, and catechins were 505, 2386, and 712 mg/100 g DW, respectively (agitated cultures of cv. Helos). The extracts from biomass grown under the best in vitro culture conditions were examined for antioxidant and antimicrobial activities. The extracts showed high or moderate antioxidant activity (DPPH, reducing power, and chelating activity assays), high activity against Gram-positive bacteria, and strong antifungal activity. Additionally, experiments with phenylalanine feeding (1 g/L) in agitated cultures were performed reaching the highest enhancement of the total contents of flavonoids, phenolic acids, and catechins on day 7 after the addition of the biogenetic precursor (2.33-, 1.73- and 1.33-fold, respectively). After feeding, the highest accumulation of polyphenols was detected in the agitated culture of cv. Elixir (4.48 g/100 g DW). The high contents of metabolites and the promising biological properties of the biomass extracts are interesting from a practical point of view.

Optimization of Callus Induction with Enhancing Production of Phenolic Compounds Production and Antioxidants Activity in Callus Cultures of Nepeta binaloudensis Jamzad (Lamiaceae)

BACKGROUND

World Health Organization (WHO) reported that more than 80% of people in the world use herbal traditional medicines nowadays. Many endemic medicinal plants, especially Nepeta species, are facing to extinction as a result of high harvesting, limited distribution, and habitat destruction.Tissue culture is a successful method for plant secondary metabolites production. Nepeta binaloudensis is a medicinal plant belonging to family Lamiaceae.

OBJECTIVE

Our study was focused on devising an optimum procedure for callus induction and phenolic compounds production in N. binaloudensis. First, we are focused on finding suitable explants and media for callus induction. Then, subsequent experiments were conducted to find an optimal concentration of plant growth regulators (PGRs) and reduced- glutathione for maximum biomass production, and phenolic compounds production in calli.

MATERIAL AND METHOD

In this study, the usage of whole plant grown in Hoagland nutrient solution, were used as a source of explants. Also, different media including, ½ MS, MS, and B5 and different combination of PGRs (NAA and BAP) were used for optimization of calli induction.

RESULTS

Based on the results of the first experiment, leaf-originated explants, and macro half strength MS (½ MS) medium were used for the next experiments. The highest FW (Fresh Weight) and DW (Dry Weight) of calli were observed in ½ MS medium, supplemented with 2 μM/L reduced-glutathione, 2 mg.L-1 BAP, and 2 mg.L-1 NAA. The maximum amount of total phenolic, flavonoid, tannin contents and free-radical scavenger were observed in calli which were grown in ½ MS medium supplemented with 2 μM/L reduced-glutathione, 2 mg.L-1 BAP, and 2 mg.L-1 NAA.

CONCLUSION

Our study finds the optimum condition for calli induction and phenolic compounds production in N. binaloudensis.

Toward enhanced hyperforin production in St. John's wort root cultures

During the past decades, several trials targeted a stable, sustainable and economic production of St. John's wort (Hypericum perforatum) extract. The value of this extract stems from its use to treat depression and skin irritation due to its hyperforin content. Previously, hyperforin-forming in vitro root cultures were established. Here, detailed growth and production kinetics have been analyzed over 40 days of cultivation. In the first 10 days, sucrose was completely hydrolyzed to glucose and fructose. The ammonium consumption supported the increase in the biomass and hyperforin production. When sucrose was replaced with glucose/fructose, the linear growth phase started 6 days earlier and resulted in a higher space-time-yield. The maximum hyperforin production was 0.82 mg L^-1 day^-1, which was 67 % higher than in the sucrose-supplemented standard cultivation. Buffering the sucrose-supplemented medium with phosphate caused a 2.7-fold increase in the product to biomass yield coefficient. However, the combination of monosaccharides and buffering conditions did not cause an appreciable improvements in the production performance of the shake flask approaches. A potential scalability from flask to lab-scale stirred bioreactors has been demonstrated. The results obtained offer a basis for a scalable production of hyperforin and a sustainable source for a tissue culture-based phytomedicine.

Chitosan oligosaccharides affect xanthone and VOC biosynthesis in Hypericum perforatum root cultures and enhance the antifungal activity of root extracts

Water-soluble chitosan oligosaccharides (COS) affect xanthone and volatile organic compound content, as well as antifungal activity against human pathogenic fungi of extracts obtained from Hypericum perforatum root cultures. Several studies have demonstrated the elicitor power of chitosan on xanthone biosynthesis in root cultures of H. perforatum. One of the major limitations to the use of chitosan, both for basic and applied research, is the need to use acidified water for solubilization. To overcome this problem, the elicitor effect of water-soluble COS on the biosynthesis of both xanthones and volatile organic compounds (VOCs) was evaluated in the present study. The analysis of xanthones and VOCs was performed by HPLC and GC-MS headspace analysis. The obtained results showed that COS are very effective in enhancing xanthone biosynthesis. With 400 mg L^-1 COS, a xanthone content of about 30 mg g^-1 DW was obtained. The antifungal activity of extracts obtained with 400 mg L^-1 COS was the highest, with MIC₅₀ of 32 µg mL^-1 against Candida albicans and 32-64 µg mL^-1 against dermatophytes, depending on the microorganism. Histochemical investigations suggested the accumulation of isoprenoids in the secretory ducts of H. perforatum roots. The presence of monoterpenes and sesquiterpenes was confirmed by the headspace analysis. Other volatile hydrocarbons have been identified. The biosynthesis of most VOCs showed significant changes in response to COS, suggesting their involvement in plant-fungus interactions.

Stimulation of secondary metabolites by copper and gold nanoparticles in submerge adventitious root cultures of Stevia rebaudiana (Bert.)

Nanotechnology is one of the advance technologies that almost found implications in every field of science. The importance is due to the unique properties of nanoparticles. In this study, bimetallic alloys of copper (Cu) and gold (Au) were tested in submerge root cultures of Stevia rebaudiana for production of biomass and secondary metabolites. A known amount of inoculum roots were submerged in liquid Murashige and Skoog medium containing combination of naphthalene acetic acid (NAA; 0.5 mg l^-1) and different ratios of nanoparticles (NPs). NAA augmented medium was used as control. The addition of nanoparticles (30 µg l^-1) stimulated biomass accumulation (1.447 g/flask) on 27th day of log phases. The maximum total phenolics content (TPC; 16.17 mg/g-DW) and total flavonoids content (TFC; 4.20 mg/g-DW) were displayed using AuCu-NPs (1:3) and NAA. The same combinations enhanced total phenolic production (TPP; 116 mg/L) and total flavonoid production (TFP; 29.5 mg/L) in submerged cultures. A strong correlation was observed between phenolics, flavonoids and dry biomass. Moreover, maximum 1, 1-diphenyl-2-picrylhydrazyl (DPPH) activity of 79% was displayed by addition of AuCu (1:3) nanoparticles. In conclusion, nanoparticles application has shown a positive effect in enhancing biomass and secondary metabolites production in adventitious root cultures of Stevia rebaudiana.

Chemical characterization and prebiotic activity of fructo-oligosaccharides from Stevia rebaudiana (Bertoni) roots and in vitro adventitious root cultures

Stevia rebaudiana (Bertoni) is widely studied because of its foliar steviol glycosides. Fructan-type polysaccharides were recently isolated from its roots. Fructans are reserve carbohydrates that have important positive health effects and technological applications in the food industry. The objective of the present study was to isolate and characterize fructo-oligosaccharides (FOSs) from S. rebaudiana roots and in vitro adventitious root cultures and evaluate the potential prebiotic effect of these molecules. The in vitro adventitious root cultures were obtained using a roller bottle system. Chemical analyses (gas chromatography-mass spectrometry, (1)H nuclear magnetic resonance, and off-line electrospray ionization-mass spectrometry) revealed similar chemical properties of FOSs that were obtained from the different sources. The potential prebiotic effects of FOSs that were isolated from S. rebaudiana roots enhanced the growth of both bifidobacteria and lactobacilli, with strains specificity in their fermentation ability.

Metabolic Profile and Root Development of Hypericum perforatum L. In vitro Roots under Stress Conditions Due to Chitosan Treatment and Culture Time

The responses of Hypericum perforatum root cultures to chitosan elicitation had been investigated through (1)H-NMR-based metabolomics associated with morpho-anatomical analyses. The root metabolome was influenced by two factors, i.e., time of culture (associated with biomass growth and related "overcrowding stress") and chitosan elicitation. ANOVA simultaneous component analysis (ASCA) modeling showed that these factors act independently. In response to the increase of biomass density over time, a decrease in the synthesis of isoleucine, valine, pyruvate, methylamine, etanolamine, trigonelline, glutamine and fatty acids, and an increase in the synthesis of phenolic compounds, such as xanthones, epicatechin, gallic, and shikimic acid were observed. Among the xanthones, brasilixanthone B has been identified for the first time in chitosan-elicited root cultures of H. perforatum. Chitosan treatment associated to a slowdown of root biomass growth caused an increase in DMAPP and a decrease in stigmasterol, shikimic acid, and tryptophan levels. The histological analysis of chitosan-treated roots revealed a marked swelling of the root apex, mainly due to the hypertrophy of the first two sub-epidermal cell layers. In addition, periclinal divisions in hypertrophic cortical cells, resulting in an increase of cortical layers, were frequently observed. Most of the metabolic variations as well as the morpho-anatomical alterations occurred within 72 h from the elicitation, suggesting an early response of H. perforatum roots to chitosan elicitation. The obtained results improve the knowledge of the root responses to biotic stress and provide useful information to optimize the biotechnological production of plant compounds of industrial interest.

Hyperforin production in Hypericum perforatum root cultures

Extracts of the medicinal plant Hypericum perforatum are used to treat depression and skin irritation. A major API is hyperforin, characterized by sensitivity to light, oxygen and temperature. Total synthesis of hyperforin is challenging and its content in field-grown plants is variable. We have established in vitro cultures of auxin-induced roots, which are capable of producing hyperforin, as indicated by HPLC-DAD and ESI-MS analyses. The extraction yield and the productivity upon use of petroleum ether after solvent screening were ∼5 mg/g DW and ∼50 mg/L culture after six weeks of cultivation. The root cultures also contained secohyperforin and lupulones, which were not yet detected in intact plants. In contrast, they lacked another class of typical H. perforatum constituents, hypericins, as indicated by the analysis of methanolic extracts. Hyperforins and lupulones were stabilized and enriched as dicyclohexylammonium salts. Upon up-scaling of biomass production and downstream processing, H. perforatum root cultures may provide an alternative platform for the preparation of medicinal extracts and the isolation of APIs.

In vitro antifungal activity of extracts obtained from Hypericum perforatum adventitious roots cultured in a mist bioreactor against planktonic cells and biofilm of Malassezia furfur

Xanthone-rich extracts from Hypericum perforatum root cultures grown in a Mist Bioreactor as antifungal agents against Malassezia furfur. Extracts of Hypericum perforatum roots grown in a bioreactor showed activity against planktonic cells and biofilm of Malassezia furfur. Dried biomass, obtained from roots grown under controlled conditions in a ROOTec mist bioreactor, has been extracted with solvents of increasing polarity (i.e. chloroform, ethyl acetate and methanol). The methanolic fraction was the richest in xanthones (2.86 ± 0.43 mg g(-1) DW) as revealed by HPLC. The minimal inhibitory concentration of the methanol extract against M. furfur planktonic cells was 16 μg mL(-1). The inhibition percentage of biofilm formation, at a concentration of 16 μg mL(-1), ranged from 14% to 39%. The results show that H. perforatum root extracts could be used as new antifungal agents in the treatment of Malassezia infections.

Enhanced production of flavonoids by methyl jasmonate elicitation in cell suspension culture of Hypericum perforatum

Background

Flavonoids of Hypericum perforatum are important secondary metabolites which have been widely utilized in medicine for a range of purposes. The use of methyl jasmonate (MeJA) elicitation for the enhancement of flavonoid production in cell suspension culture of H. perforatum would be an efficient alternative method for the flavonoid production.

Results

MeJA influenced the cells growth and flavonoid production. The optimal elicitation strategy was treatment of the cell cultures with 100 μmol/L MeJA on day 15, which resulted in the highest flavonoid production (280 mg/L) and 2.7 times of control cultures. The activities of catalase (CAT) were inhibited after MeJA treatment in the cell cultures, while the activities of phenylalanine ammonia lyase (PAL) increased, which led to the enhancement of flavonoid production.

Conclusion

MeJA elicitation is a useful method for the enhancement of flavonoid production in cell suspension culture of H. perforatum.

Yield enhancement strategies for the production of picroliv from hairy root culture of Picrorhiza kurroa Royle ex Benth

Fast-growing hairy root cultures of Picrorhiza kurroa induced by Agrobacterium rhizogenes offers a potential production system for iridoid glycosides. In present study we have investigated the effects of various nutrient medium formulations viz B5, MS, WP and NN, and sucrose concentrations (1-8%) on the biomass and glycoside production of selected clone (14-P) of P. kurroa hairy root. Full strength B5 medium was found to be most suitable for maximum biomass yield on the 40th day of culture (GI = 32.72 ± 0.44) followed by the NN medium of the same strength (GI = 22.9 ± 0.43). Secondary metabolite production was 1.1 and 1.3 times higher in half strength B5 medium respectively in comparison to MS medium. Maximum biomass accumulation along with the maximum picroliv content was achieved with 4% sucrose concentration in basal medium. RT vitamin and Thiamine-HCl effected the growth and secondary metabolite production of hairy roots growing on MS medium but did not show any effect on other media. The pH of the medium played significant role in growth and secondary metabolite production and was found to be highest at pH 6.0 while lowest at pH 3.0 and pH 8.0. To enhance the production of biomass and Picroliv 5 liter working capacity bioreactor was used, 27-fold (324 g FW) higher growth was observed in bioreactor than shake flask and secondary metabolite production was similarly enhanced.

Hypericins: biotechnological production from cell and organ cultures

Hypericum perforatum L. (St. John's wort), a perennial flowering plant native to Europe, is widely used as a medicinal plant and has a long history of its use in the treatment of various ailments. Currently, H. perforatum is widely used as an herbal remedy for the treatment of mild to moderate depression. Hypericins are natural napthodianthrone compounds produced from H. perforatum (St. John's wort) which are having antitumor, antiviral (i.e., against human immunodeficiency and hepatitis C virus), antineoplastic, and antidepressant properties. Currently, field-grown plant materials are generally used for the commercial production of hypericins. It has been reported that hypericin accumulation in natural plants is influenced by different ecological and environmental conditions including light intensity, nitrogen availability, temperature, seasons, and growing regions. Therefore, up to 17-fold and 13-fold differences in hypericin and pseudohypericin amounts, respectively, are reported in different phytopharmaceutical preparations. Plant cell and organ cultures are effective systems for producing natural products, and attempts were made for the production of biomass and stable concentrations of hypericins through in vitro cultures of H. perforatum. Cell, callus, shoot, plantlet, and adventitious root cultures have been established and various chemical and physical factors which influence the biomass and secondary metabolite accumulation have been investigated. Large-scale plantlet and adventitious root cultures have also been attempted in H. perforatum in bioreactors, and various strategies have been applied for the production of higher biomass and secondary products. This review describes the biotechnological approaches employed for the production of hypericins and focuses upon the challenges and future prospects.

Production of the quinone-methide triterpene maytenin by in vitro adventitious roots of Peritassa campestris (Cambess.) A.C.Sm. (Celastraceae) and rapid detection and identification by APCI-IT-MS/MS

Establishment of adventitious root cultures of Peritassa campestris (Celastraceae) was achieved from seed cotyledons cultured in semisolid Woody Plant Medium (WPM) supplemented with 2% sucrose, 0.01% PVP, and 4.0 mg L⁻¹ IBA. Culture period on accumulation of biomass and quinone-methide triterpene maytenin in adventitious root were investigated. The accumulation of maytenin in these roots was compared with its accumulation in the roots of seedlings grown in a greenhouse (one year old). A rapid detection and identification of maytenin by direct injection into an atmospheric-pressure chemical ionization ion trap tandem mass spectrometer (APCI-IT-MS/MS) were performed without prior chromatographic separation. In vitro, the greatest accumulation of biomass occurred within 60 days of culture. The highest level of maytenin—972.11 μg·g⁻¹ dry weight—was detected at seven days of cultivation; this value was 5.55-fold higher than that found in the roots of seedlings grown in a greenhouse.

A strategy for enrichment of the bioactive sphingoid base-1-phosphates produced by Hypericum perforatum L. in a balloon type airlift reactor

An efficient enrichment method using immobilized metal affinity chromatography (IMAC) was developed for selective extraction of bioactive sphingoid base-1-phosphates (SB1Ps) from adventitious roots of Hypericum perforatum cultured in bioreactor. The phosphate-selective IMAC enrichment coupled with LC-MS/MS enabled sensitive analysis of low-abundance SB1Ps present in the root biomass, which would not be feasible otherwise due to severe interferences from complex biological matrices. The time-dependent growth rate and production of SB1Ps from adventitious roots were investigated. The level of phytosphingosine-1-phosphate, which was found to be the major SB1Ps, reached a maximum amount of 635.6pmolpergram of dry weight after 3weeks of culture and decreased between 3 and 5weeks of culture subsequently. On the other hand, sphingosine-1-phosphate and sphinganine-1-phosphate were present at levels of 18.91 and 73.15pmolpergram of dry weight, respectively, after a week of culture and their level decreased thereafter.