In vitro propagation, carotenoid, fatty acid and tocopherol content of Ajuga multiflora Bunge

Sustainable Production of Ajuga Bioactive Metabolites Using Cell Culture Technologies: A Review

The genus Ajuga (Lamiaceae) is rich in medicinally important species with biological activities ranging from anti-inflammatory, antitumor, neuroprotective, and antidiabetic to antibacterial, antiviral, cytotoxic, and insecticidal effects. Every species contains a unique and complex mixture of bioactive metabolites-phytoecdysteroids (PEs), iridoid glycosides, withanolides, neo-clerodane terpenoids, flavonoids, phenolics, and other chemicals with high therapeutic potential. Phytoecdysteroids, the main compounds of interest, are natural anabolic and adaptogenic agents that are widely used as components of dietary supplements. Wild plants remain the main source of Ajuga bioactive metabolites, particularly PEs, which leads to frequent overexploitation of their natural resources. Cell culture biotechnologies offer a sustainable approach to the production of vegetative biomass and individual phytochemicals specific for Ajuga genus. Cell cultures developed from eight Ajuga taxa were capable of producing PEs, a variety of phenolics and flavonoids, anthocyanins, volatile compounds, phenyletanoid glycosides, iridoids, and fatty acids, and demonstrated antioxidant, antimicrobial, and anti-inflammatory activities. The most abundant PEs in the cell cultures was 20-hydroxyecdysone, followed by turkesterone and cyasterone. The PE content in the cell cultures was comparable or higher than in wild or greenhouse plants, in vitro-grown shoots, and root cultures. Elicitation with methyl jasmonate (50-125 µM) or mevalonate and induced mutagenesis were the most effective strategies that stimulated cell culture biosynthetic capacity. This review summarizes the current progress in cell culture application for the production of pharmacologically important Ajuga metabolites, discusses various approaches to improve the compound yield, and highlights the potential directions for future interventions.

Analysis of Lipophilic Antioxidants in the Leaves of Kaempferia parviflora Wall. Ex Baker Using LC-MRM-MS and GC-FID/MS

Lipophilic metabolites such as carotenoids, fatty acids, vitamin K1, phytosterols, and tocopherols are important antioxidants that are used in the cosmetics, foods, and nutraceutical industries. Recently, there has been a growing demand for the use of byproducts (wastes) as a potential source of industrially important compounds. The leaves of Kaempferia parviflora (black ginger) (KP-BG) are major byproducts of KP-BG cultivation and have been reported to contain several bioactive metabolites; however, the composition of lipophilic metabolites in KP-BG leaves has not been examined. In this study, the lipophilic antioxidant profile was analyzed in the leaves of KP-BG plants grown in vitro and ex vitro. Lipophilic compounds, namely carotenoids (80.40-93.84 µg/g fresh weight (FW)), tocopherols (42.23-46.22 µg/g FW), phytosterols (37.69-44.40 µg/g FW), and vitamin K1 (7.25-7.31 µg/g FW), were quantified using LC-MRM-MS. The fatty acid profile of the KP-BG leaves was identified using GC-FID/MS. The content of individual lipophilic compounds varied among the KP-BG leaves. Ex vitro KP-BG leaves had high levels of lutein (44.38 µg/g FW), α-carotene (14.79 µg/g FW), neoxanthin (12.30 µg/g FW), β-carotene (11.33 µg/g FW), violaxanthin (11.03 µg/g FW), α-tocopherol (39.70 µg/g FW), α-linolenic acid (43.12%), palmitic acid (23.78%), oleic acid (12.28%), palmitoleic acid (3.64%), total carotenoids (93.84 µg/g FW), and tocopherols (46.22 µg/g FW) compared with in vitro KP-BG leaves. These results indicate that ex-vitro-grown KP-BG leaves could be used as a valuable natural source for extracting important lipophilic antioxidants.

Accumulation of Ascorbic Acid in Tomato Cell Culture: Influence of the Genotype, Source Explant and Time of In Vitro Cultivation

The production and commercialization of natural antioxidants is gaining increasing importance due to their wide range of biological effects and applications. In vitro cell culture is a valuable source of plant bioactive compounds, especially those highly dependent on environmental factors. Nonetheless, research on the accumulation in plant cultured cells of water-soluble antioxidant vitamins, such as the ascorbic acid (AsA), is very limited. Tomato fruits are a main dietary source of vitamin C and in this work, we explored the potential of in vitro cultured cells for AsA accumulation. Specifically, using a full factorial design, we examined the effect of the source explant, the time in tissue culture and the genetic difference present in two Introgression Line (IL7-3 and IL12-4) that harbor Quantitative Trait Loci (QTLs) for ascorbic acid in fruits. Moreover, we performed an expression analysis of genes involved in AsA metabolism to highlight the molecular mechanisms that can account for the difference between fruit explants and calli. Our work indicated that cultured tomato cells accumulate AsA well beyond the amount present in fruits and that the three factors under investigation and their interaction significantly influence AsA accumulation. The time in tissue culture is the main single factor and, different from the expectations for secondary metabolites, explants from unripe, mature green fruits provided the highest increase in AsA. Moreover, in controlled conditions the genetic differences between the ILs and the control genotype are less relevant for calli cultivated for longer time. Our work showed the potential of tomato cell culture to produce AsA and prompt further refinements towards its possible large-scale exploitation.

Micropropagation and Quantification of Bioactive Compounds in Mertensia maritima (L.) Gray

The goal of this study was to establish an efficient protocol for the large-scale propagation of Mertensia maritima (L.) Gray, and evaluate the carotenoid, fatty acid, and tocopherol contents in the leaves of in vitro regenerated shoots. Surface-disinfected node and shoot tip explants were placed on semisolid Murashige and Skoog (MS) medium with 0-16 µM N⁶-benzyladenine (BA), kinetin, (KN), and thidiazuron (TDZ) alone, or in combination with, 1 or 2 µM α-naphthaleneacetic acid (NAA). Of the three different cytokinins employed, TDZ elicited the best results for axillary shoot proliferation. A maximum frequency of shoot initiation above 84%, with a mean of 8.9 and 4.8 shoots per node and shoot tip, respectively, was achieved on the culture medium supplemented with 4 µM TDZ. A combination of TDZ + NAA significantly increased the percentage of multiple shoot formation and number of shoots per explant. The best shoot induction response occurred on MS medium with 4 µM TDZ and 1 µM NAA. On this medium, the node (93.8%) and shoot tip (95.9%) explants produced an average of 17.7 and 8.6 shoots, respectively. The highest root induction frequency (97.4%) and number of roots per shoot (25.4), as well as the greatest root length (4.2 cm), were obtained on half-strength MS medium supplemented with 4 µM indole-3-butyric acid (IBA). The presence of six carotenoids and α-tocopherol in the leaf tissues of M. maritima was confirmed by HPLC. Gas chromatography-mass spectrometry analysis confirmed the presence of 10 fatty acids, including γ-linolenic acid and stearidonic acid in the leaf tissues of M. maritima. All-E-lutein (18.49 μg g^-1 fresh weight, FW), α-tocopherol (3.82 μg g^-1 FW) and α-linolenic acid (30.37%) were found to be the significant compounds in M. maritima. For the first time, a successful protocol has been established for the mass propagation of M. maritima with promising prospects for harnessing its bioactive reserves.

Development of a NIR Method for the In-Line Quantification of the Total Polyphenolic Content: A Study Applied on Ajuga genevensis L. Dry Extract Obtained in a Fluid Bed Process

This study describes an innovative in-line near-infrared (NIR) process monitoring method for the quantification of the total polyphenolic content (TPC) of Ajuga genevensis dry extracts. The dry extract was obtained in a fluidized bed processor, by spraying and adsorbing a liquid extract onto an inert powder support. NIR spectra were recorded continuously during the extract’s spraying process. For the calibration of the in-line TPC quantification method, samples were collected during the entire process. The TPC of each sample was assessed spectroscopically, by applying a UV-Vis reference method. The obtained values were further used in order to develop a quality OPLS prediction model by correlating them with the corresponding NIR spectra. The final dry extract registered good flowability and compressibility properties, a concentration in active principles three times higher than the one of the liquid extract and an overall process yield of 85%. The average TPC’s recovery of the NIR in-line prediction method, compared with the reference UV-Vis one, was 98.7%, indicating a reliable monitoring method which provided accurate predictions of the TPC during the process, permitting a good process overview and enabling us to establish the process’s end point at the exact moment when the product reaches the desired TPC concentration.

β-Ecdysterone accumulation and regulation in Ajuga multiflora Bunge suspension culture

Ajuga multiflora Bunge cells contain β-ecdysterone (β-EC) that regulates the molting process of insect larvae. In this study, different conditions of culture have been studied to optimize the production of β-EC. A. multiflora Bunge growth fitted the curve of logistic equation with one growth cycle of 17 days. The electric conductivity of medium had a negative correlation with not only the weight of dry cell but also the β-EC accumulation, and thus, could be used for monitoring the peak of both cell growth and β-EC accumulation. The pH value of the culture medium varied from 4.67 to 5.84 and reached the maximum at the end of the culture (on the 17th day). The relation of cell growth and nutrient consumption in A. multiflora Bunge cell suspension culture was distinctly correlated. Continuous subculture caused a reduction in β-EC synthesis; passages 7-15, the β-EC content declined (p < 0.05). At passage 11, the β-EC content was only 42.72% of that at passage 5. Additives such as mevalonic acid (MVA), l-phenylalanine (l-Phe), α-pinene, terpineol, and nitric oxide (NO) in the suspension culture medium, could significantly promote the cell growth and stimulate β-EC accumulation. The optimal concentrations of l-Phe, MVA, terpineol, and α-pinene were 0.2 mmol/l, 10 mg/l, 1 mmol/l and 6 mmol/l, respectively, with the β-EC concentrations as 1.914 ± 0.1948 mg/g (p < 0.01), 6.012 ± 0.4252 mg/g (p < 0.01), 5.147 ± 0.4819 mg/g (p < 0.01), 2.801 ± 0.1253 mg/g (p < 0.01), respectively. The optimal concentration of sodium nitroprusside, the provider of NO, was 3 mmol/l with the β-EC concentration 2.87 ± 0.2493 mg/g (p < 0.01). The results offer a strategy for massive production of β-EC.

Micropropagation and Subsequent Enrichment of Carotenoids, Fatty Acids, and Tocopherol Contents in Sedum dasyphyllum L

A promising micropropagation protocol has been systematically established and demonstrated for the enhanced production of carotenoids, tocopherol and fatty acids in shoot tissues of Sedum dasyphyllum. Shoot tip explants were grown on Murashige and Skoog (MS) medium. Different concentrations of N⁶-benzyladenine (BA) or thidiazuron (TDZ) alone or in combination with α-naphthaleneacetic acid (NAA) were tested in order to stimulate multiple shoot production. Ideal shoot induction (100%) and maximized shoot numbers (36.4) were obtained on explants cultured on media incorporated with 2 μM BA and 1 μM NAA combinations. The in vitro-developed shoots rooted best on half-strength MS media incorporated with 2 μM indole 3-butyric acid. Plantlets were effectively acclimatized in the greenhouse with 100% survival rate. The composition and contents of bioactive compounds such as carotenoids, tocopherol and fatty acids in shoot tissues of S. dasyphyllum were investigated using HPLC and GC-MS. The most abundant carotenoid in the shoot tissue was all-E-lutein (40.3-70.5 μg g^-1 FW) followed by 9'-Z-neoxanthin (5.3-9.9 μg g^-1 FW), all-E-violaxanthin (4.4-8.2 μg g^-1 FW), and all-E-β-carotene (1.6-3.6 μg g^-1 FW). The α-tocopherol contents of in vitro-raised shoots was 6.5-fold higher than shoots of greenhouse-grown plants. The primary fatty acids found in shoot tissues were α-linolenic acid (32.0-39.3%), linoleic acid (27.4-38.2%), palmitic acid (13.3-15.5%), and stearic acid (5.2-12.2%). In all, summarizing the findings, the micropropagated S. dasyphyllum showed significant enrichment of valuable bioactive carotenoids (92.3 μg g^-1 FW), tocopherols (14.6 μg g^-1 FW), and α-linolenic acid (39.3%) compared to their greenhouse counterparts. The protocol demonstrated here could be applied for the mass propagation and production of enhanced bioactive compounds from S. dasyphyllum with credibility.

Micropropagation of Ajuga species: a mini review

The genus Ajuga L., belonging to Lamiaceae family, is widespread. The demand for Ajuga species has risen sharply because of their medicinal, ornamental, and pharmacological properties. These wide-ranging plants are being rapidly depleted due to over-collection for ornamental and medicinal purposes, as well as by habitat destruction and deforestation. Ajuga boninsimae, A. bracteosa, A. ciliate, A. genevensis, A. incisa, A. makinoi, A. multiflora, A. pyramidalis, A. shikotanensis, A. reptans, and A. vestita are categorized and protected as endangered plants. In vitro plant culture has therefore emerged for the conservation and mass clonal propagation of rare plants. This mini-review covers the current in vitro scenario in the propagation of Ajuga species. Adventitious or axillary shoots are initiated on the leaf, petiole and internodes, as well as roots, nodes, and shoot tip explants. Shoot induction is predominantly dependent on plant growth regulators added to the culture medium. Full- or half-strength Murashige and Skoog medium with or without auxin is used for in vitro rooting. Rooted shoots need to be acclimatized in the greenhouse with an estimated 82-100% survival rate.

Ripening improves the content of carotenoid, α-tocopherol, and polyunsaturated fatty acids in tomato (Solanum lycopersicum L.) fruits

The tomato fruits during different stages of ripening have been extensively characterized for nutritionally important bioactives; however, changes in fatty acid composition are not available. Thus, in the present study, changes in fatty acid, along with carotenoid and α-tocopherol, were studied during the six stages of ripening. Fruits were harvested at the green, breaker, turning, pink, light red, and red stages, which occurred at means of 30, 35, 40, 46, 50, and 55 days after anthesis (DAE), respectively. During the ripening process, profiles of all the metabolites altered significantly (p < 0.05). All-E-lycopene content increased from the breaker (0.21 μg/g FW) to the red stage (30.6 μg/g FW), while all-E-lutein was slightly increased during initial stages of ripening and then decreased significantly, with the highest (4.15 μg/g FW) in the fruits of the pink stage. Furthermore, the contents of α-tocopherol increased during ripening, and its increase was highest between light red to the red stages. In all the ripening stages, linoleic acid (C18:2n6c) was found in the highest quantity (42.3-49.2%), followed by oleic (C18:1n9c; 20.1-26.6%) and palmitic acids (C16:0; 16.6-17.7%). With fruit ripening, the ratio of polyunsaturated fatty acids and saturated fatty acids (PUFAs:SFAs) was increased significantly from 1.89 (green) to 2.19 (red). Interestingly, the oleic acid proportions correlated inversely with linoleic (r = -0.450) and α-linolenic acid (r = -0.904), during all the stages of ripening. The highest and lowest contents of oleic acid and linoleic acid (26.7 and 42.3%, respectively) were recorded in the fruits of stage 3 (turning). In conclusion, ripening in tomatoes is accompanied by significant increases in carotenoids and α-tocopherol, as well as by concomitant increases in PUFAs.

Nanomaterials in plant tissue culture: the disclosed and undisclosed

Nanomaterial integration into tissue culture for prospective uninterrupted progressive plant tissue culture.