Antioxidant activity and high-performance liquid chromatographic analysis of phenolic compounds during in vitro callus culture of Plantago ovata Forsk. and effect of exogenous additives on accumulation of phenolic compounds

Evaluation and optimisation of phenolic compounds extracted by supercritical carbon dioxide from the seeds of Plantago ovata and their comparison with conventional extraction

This study's main objectives are to evaluate and confirm the effects of the extraction process, operating conditions, solvent type and solvent polarity on the yield and quality of the extracts. Supercritical carbon dioxide (scCO2) and Soxhlet were specially used in this study to extract bioactive chemicals from the seeds of a natural plant known as Plantago ovata. No studies have been published so far regarding the extraction from the seeds of this plant using scCO2.The effects of three operating parameters (pressure, temperature and particle size) on the extraction yield, total phenolic content, total flavonoid content (TFC), total tannin content (TTC) and antioxidant activity were assessed in this study using the Box-Behnken statistical experimental design (BBD). The chemical components in the extracts were separated and identified using gas chromatography mass spectrometry. According to the antioxidant activity results, scCO2 failed to produce bioactive compounds with interesting properties when operated within operating range conditions.

Phenolic Compounds from Wild Plant and In Vitro Cultures of Ageratina pichichensis and Evaluation of Their Antioxidant Activity

Ageratina pichichensis, is commonly used in traditional Mexican medicine. In vitro cultures were established from wild plant (WP) seeds, obtaining in vitro plant (IP), callus culture (CC), and cell suspension culture (CSC) with the objective to determine total phenol content (TPC) and flavonoids (TFC), as well as their antioxidant activity by DPPH, ABTS and TBARS assays, added to the compound's identification and quantification by HPLC, from methanol extracts obtained by sonication. CC showed significantly higher TPC and TFC than WP and IP, while CSC produced 2.0-2.7 times more TFC than WP, and IP produced only 14.16% TPC and 38.8% TFC compared with WP. There were identified compounds such as epicatechin (EPI), caffeic acid (CfA), and p-coumaric acid (pCA) in in vitro cultures that were not found in WP. The quantitative analysis shows gallic acid (GA) as the least abundant compound in samples, whereas CSC produced significantly more EPI and CfA than CC. Despite these results, in vitro cultures show lower antioxidant activity than WP, for DPPH and TBARS WP > CSC > CC > IP and ABTS WP > CSC = CC > IP. Overall, A. pichichensis WP and in vitro cultures produce phenolic compounds with antioxidant activity, especially CC and CSC, which are shown to be a biotechnological alternative for obtaining bioactive compounds.

Impact of Plantago ovata Forsk leaf extract on morpho-physio-biochemical attributes, ions uptake and drought resistance of wheat (Triticum aestivum L.) seedlings

The present study was conducted to examine the potential role of Plantago ovata Forsk leaf extract (POLE) which was applied at various concentration levels (control, hydropriming, 10, 20, 30, and 40% POLE) to the wheat (Triticum aestivum L.) seedlings. Drought stressed was applied at 60% osmotic potential (OM) to the T. aestivum seedlings to study various parameters such as growth and biomass, photosynthetic pigments and gas exchange characteristics, oxidative stress and response of various antioxidants and nutritional status of the plants. Various growth parameters such as gaseous exchange attributes, antioxidants and nutritional status of T. aestivum were investigated in this study. It was evident that drought-stressed condition had induced a negative impact on plant growth, photosynthetic pigment, gaseous exchange attributes, stomatal properties, and ion uptake by different organs (roots and shoots) of T. aestivum. The decrease in plant growth resulted from oxidative stress and overcome by the antioxidant (enzymatic and non-enzymatic) compounds, since their concentration increased in response to dehydration. Seed priming with POLE positively increased plant growth and photosynthesis, by decreasing oxidative stress indicators and increasing activities of antioxidant (enzymatic and non-enzymatic) compounds, compared to the plants which were grown without the application of POLE. Our results also depicted that optimum concentration of POLE for T. aestivum seedlings under drought condition was 20%, while further increase in POLE (30 and 40%) induced a non-significant (P < 0.05) effect on growth (shoot and root length) and biomass (fresh and dry weight) of T. aestivum seedling. Here we concluded that the understanding of the role of seed priming with POLE in the increment of growth profile, photosynthetic measurements and nutritional status introduces new possibilities for their effective use in drought-stressed condition and provides a promising strategy for T. aestivum tolerance against drought-stressed condition.

Antioxidative Properties and Phenolic Profile of the Core, Pulp and Peel of Commercialized Kiwifruit by LC-ESI-QTOF-MS/MS

The kiwifruit is cultivated globally due to its diversity of phytochemicals, especially phenolic compounds, which have antioxidant, anti-inflammatory and anti-cancer medical effects. However, only the pulp of the kiwifruit is consumed, while the peels and cores—which are also rich in phytochemicals—are usually wasted. Meanwhile, detailed information on the comparison among the three parts is still limited. In this study, the antioxidant potentials in the core, pulp, and peel of the three most commercialized kiwifruit cultivars (Australian-grown Hayward kiwifruit, New Zealand-grown Zesy002 kiwifruit, and New Zealand-grown organic Hayward kiwifruit) were selected. Their antioxidant capacities were tested, and their phenolic profiles were identified and characterized by liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS/MS). The antioxidant results showed that the peel of New Zealand-grown organic Hayward kiwifruit contained the highest total phenolic content (9.65 mg gallic acid equivalent (GAE) mg/g) and total antioxidant capacity (4.43 mg ascorbic acid equivalent (AAE) mg/g), respectively. In addition, the antioxidant capacity of the peel is generally higher than that of the pulp and cores in all species, especially ABTS (2,2-Azino-bis-3ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging ability), ranging from 13.25 mg AAE/g to 18.31 mg AAE/g. The LC-ESI-QTOF-MS/MS tentatively identified the phenolic compounds present in the three kiwifruit species, including 118 unique compounds in kiwifruit peel, 12 unique compounds in the kiwifruit cores, and three unique compounds in kiwifruit pulp. The comprehensive characterization of the phenolics in the kiwifruits’ parts indicates the importance of their waste part as a promising source of phenolics with antioxidant properties. Therefore, this study can guide the industry with meaningful information on kiwifruit waste, and can provide it with the utilization of food and pharmacological aspects.

Sustainable Design of Innovative Kiwi Byproducts-Based Ingredients Containing Probiotics

Industrial processing of kiwifruits generates a large quantity of byproducts, estimated to be one million tons per year. The resulting byproducts are rich sources of bioactive components that may be used as additives, hence minimizing economic and environmental issues. In this study, kiwifruit byproducts were used to develop added-value food-grade ingredients containing probiotics. The byproducts were divided into peels and pomace. Both residues were inoculated with a selected strain of probiotic (Lacticaseibacillus casei 431^®), and two variants were additionally enhanced with prebiotic sources (buckwheat and black rice flours). The inoculated powders were obtained by freeze-drying, and the final ingredients were coded as KP (freeze-dried kiwi peels), KBR (freeze-dried kiwi pomace and black rice flour), KPB (freeze-dried kiwi pomace and buckwheat flour), and KPO (freeze-dried kiwi pomace). The phytochemical profile was assessed using different spectrophotometric methods, such as the determination of polyphenols, flavonoids, and carotenoids. The kiwi byproduct-based formulations showed a polyphenolic content varying from 10.56 ± 0.30 mg AGE/g DW to 13.16 ± 0.33 mg AGE/g, and the survival rate of lactic acid bacteria after freeze-drying ranged from 73% to 88%. The results showed an increase in total flavonoid content from the oral to gastric environment and controlled release in the intestinal environment, whereas a maximum survival rate of probiotics at the intestinal end stage was 48%. The results of SEM and droplet size measurements revealed vesicular and polyhedral structures on curved surfaces linked by ridge sections. The CIEL*a*b* color data were strongly associated with the particular pigment in kiwi pulp, as well as the color of the additional flour. Finally, the ingredients were tested in protein bars and enhanced the value of the final food product regarding its phytochemical and probiotic content.

Optimization of Callus and Cell Suspension Cultures of Lycium schweinfurthii for Improved Production of Phenolics, Flavonoids, and Antioxidant Activity

Lycium schweinfurthii is a traditional medicinal plant grown in the Mediterranean region. As it is used in folk medicine to treat stomach ulcers, it took more attention as a source of valuable secondary metabolites. The in vitro cultures of L. schweinfurthii could be a great tool to produce secondary metabolites at low costs. The presented study aimed to introduce and optimize a protocol for inducing callus and cell suspension cultures as well as estimating phenolic, flavonoid compounds, and antioxidant activity in the cultures of the studied species. Three plant growth regulators (PGRs) were supplemented to MS medium solely or in combination to induce callus from leaf explants. The combination between 2,4-dichlorophenoxy acetic acid (2,4-D) and 1-naphthyl acetic acid (NAA) induced callus in all explants regardless of the concentration. The highest fresh weight of callus (3.92 g) was obtained on MS medium fortified with 1 mg L−1 of both 2,4-D and NAA (DN1) after 7 weeks of culture. DN1 was the best medium for callus multiplication regarding the increase in fresh weight and size of callus. Otherwise, the highest phenolics, flavonoids, and antioxidant activity against DPPH free radicals were of callus on MS fortified with 2 mg L−1 NAA (N2). The cell suspension cultures were cultivated on a liquid N2 medium with different sucrose concentrations of 5–30 g L−1 to observe the possible effects on cells’ multiplication and secondary metabolite production. The highest fresh and viable biomass of 12.01 g was obtained on N2 containing 30 g L−1 sucrose. On the other hand, the cell cultures on N2 medium of 5 and 30 g L−1 sucrose produced phenolics and flavonoids, and revealed antioxidant activity against DPPH and ABTS+ free radicals more than other sucrose concentrations. The presented protocol should be useful in the large-scale production of phenolic and flavonoid compounds from callus and cell cultures of L. schweinfurthii.

Elicitation Effects on Some Secondary Metabolites and Antioxidant Activity in Callus Cultures of Allium jesdianum Boiss. & Buhse.: Methyl Jasmonate and Putrescine

Allium jesdianum Boiss. & Buhse. is the most important species of the Amaryllidaceae family with various pharmacological properties. Three subsequent experiments (germination, callogenesis, and elicitation) were carried out as a completely randomized design with six replication. At the first study, the highest seed germination (78.33%) was achieved at chemical pre-treatment including the combination of α-naphthalene acetic acid (1 mg L-1) and benzylaminopurine (3 mg L-1) under in vitro condition. The highest callus induction (86.7%) was observed at MS/2 media, which was supplemented by NAA (1 mg L-1) and BAP (3 mg L-1) from hypocotyl explants. Then, two chemical elicitors including methyl jasmonate (MeJ) (0, 25, 50, and 100 µM) and putrescine (Pu) (0, 0.5, and 1 mM) were used to investigate their effects on different biochemical traits under callus culture. The results showed the superiority of MeJ over Pu for increasing the secondary metabolites and antioxidant activity in calluses of Allium jesdianum, compared to the control. The highest contents for total phenolics (6.02 mg GAE g-1 FW), total flavonoids (0.52 mg QE g-1 FW), and total flavonols (0.39 mg QE g-1 FW) were observed under 50 µM of MeJ. Meanwhile, the highest value for anthocyanin (8.99 µ mol g-1 FW) was achieved at 25 µM of MeJ. The highest 2,2-diphenyl-1-picrylhydrazyl activities were observed at 50 and 100 µM of MeJ. Putrescine (0.5 mM) elicitation showed only superiority for callus growth rate (0.53 mm day-1). Enhancement of desired secondary metabolites at 50 µM MeJ could be suitable for future studies in biotechnological aspects of this medicinal plant.

Beneficial Effects of Psyllium on the Prevention and Treatment of Cardiometabolic Diseases

Cardiometabolic diseases are reaching epidemic proportions worldwide. Nevertheless, current therapeutic strategies are insufficient; thus, studying novel complementary and alternative medicines remains of the upmost importance. Psyllium has been used for...

Responses to Salinity in Four Plantago Species from Tunisia

The genus Plantago is particularly interesting for studying the mechanisms of salt tolerance in plants, as it includes both halophytes and glycophytes, as well as species adapted to xeric environments. In this study, the salt stress responses of two halophytes, P. crassifolia and P. coronopus, were compared with those of two glycophytes, P. ovata and P. afra. Plants obtained by seed germination of the four species, collected in different regions of Tunisia, were subjected to increasing salinity treatments for one month under greenhouse conditions. Morphological traits and biochemical parameters, such as ion accumulation and the leaf contents of photosynthetic pigments, osmolytes, oxidative stress markers and antioxidant metabolites, were measured after the treatments. Salt-induced growth inhibition was more pronounced in P. afra, and only plants subjected to the lowest applied NaCl concentration (200 mM) survived until the end of the treatments. The biochemical responses were different in the two groups of plants; the halophytes accumulated higher Na+ and proline concentrations, whereas MDA levels in their leaves decreased, indicating a lower level of oxidative stress. Overall, the results showed that P. coronopus and P. crassifolia are the most tolerant to salt stress, and P. afra is the most susceptible of the four species. Plantago ovata is also quite resistant, apparently by using specific mechanisms of tolerance that are more efficient than in the halophytes, such as a less pronounced inhibition of photosynthesis, the accumulation of higher levels of Cl- ions in the leaves, or the activation of K+ uptake and transport to the aerial part under high salinity conditions.

The Biological Effects of Novel Nutraceuticals with Curcuminoids and Other Plant-Derived Immunomodulators and Pre-Probiotics

An effective and well-balanced immune system is pivotal for maintaining health. Diet and nutrition can affect the functioning of numerous immune parameters, with direct repercussions on homeostasis. Since our immune functions are indispensable in defending the body against pathogens and thus play a vital role in maintaining health, modulating immune response may well serve as the basis for the development of plant-based functional foods and novel nutraceuticals. This concept is currently utilized in attempts to prevent or mitigate inflammatory reactions via the development of targeted food products or active ingredients since an extended number of phytoconstituents (such as curcuminoids) are associated with beneficial effects on immunity. Immunomodulatory plant-based dietary supplements are considered effective in improving immune functions and reducing the incidence of immunological disorders or imbalances. Therefore, the main focus of this study was to evidence the beneficial biological effects such as antioxidant and antimicrobial, as well as nutritional status, biocompatibility and cell proliferation capacity and immunomodulation of two novel nutraceuticals. The first nutraceutic was based on curcuminoids and other actives from Trigonella foenum- graecum (seeds), Chelidonium majus L. (aerial parts), Taraxacum officinale L. (roots), vitamins (C, D3, A, E) and minerals (zinc) whereas the second one was made of probiotics such as Lactobacillus acidophilus and Bifidobacterium animalis subsp. Lactis combined with actives from Helianthus tuberosus (tubers) and Psyllium/Plantago ovata (husk) as herbal prebiotics.

Production of phenolic compounds and antioxidant activity via bioconversion of wheat straw by Inonotus obliquus under submerged fermentation with the aid of a surfactant

BACKGROUND

This study investigated the effect of surfactants on wheat straw biodegradation and the growth-associated generation of exo- and endo-phenolic compounds (EPC and IPC) and antioxidant activity expression by liquid-cultured Inonotus obliquus, an edible and medicinal mushroom, also known as a white rot fungus. Changes in the chemical composition and multiscale structure of wheat straw, in the production and activity of EPC and IPC and in individual flavonoids were analyzed.

RESULTS

Fungal pretreatment decreased significantly the contents of all lignocellulose components, increased and enlarged substrate porosity and caused changes in the structure of wheat straw with the aid of Triton X-100. A gradual increase in EPC and IPC production was observed up to 6.4- and 1.5-fold for 9 days. The EPC obtained on day 9 showed the highest antioxidant activity (IC₅₀ of 30.96 mg L^-1 ) against 2,2-diphenyl-1-picrylhydrazyl radicals. High-performance liquid chromatographic results indicated the presence of high amounts of epicatechin-3-gallate (ECG; (374.9 mg g^-1 ) and epigallocatechin-3-gallate (EGCG; 447.2 mg g^-1 ) in the EPC; other polyphenols were also enhanced but to a lesser extent. Surfactant supplementation was effective in enhancing flavonoid production and in increasing antioxidant activity in EPC.

CONCLUSIONS

The results indicated enhanced accumulation of phenolic compounds, particularly ECG and EGCG in Inonotus obliquus via biodegradation and bioconversion of lignocellulose residues. They also indicated enhancement in the production of several flavonoids and also an increase in antioxidant activity in the product by a surfactant-treated process, which may be a useful way of exploiting underused lignocellulosic residues to various high-added-value functional ingredients. © 2020 Society of Chemical Industry.

Enhanced Production of β-Caryophyllene by Farnesyl Diphosphate Precursor-Treated Callus and Hairy Root Cultures of Artemisia vulgaris L

Artemisia vulgaris L. produces a wide range of valuable secondary metabolites. The aim of the present study is to determine the effects of various concentrations of farnesyl diphosphate (FDP) on β-caryophyllene content in both callus and hairy root (HR) cultures regeneration from leaf explants of A. vulgaris L. Murashige and Skoog (MS) medium supplemented with various concentrations of 2,4-dichlorophenoxyacetic acid (2,4D; 4-13 μM), α-naphthaleneacetic acid (NAA; 5-16 μM), and FDP (1 and 3 μM) was used for callus induction and HR regeneration from leaf explants of A. vulgaris L. In this study, precursor-treated (2,4D 13.5 μM + FDP 3 μM) callus displayed the highest biomass fresh weight (FW)/dry weight (DW): 46/25 g, followed by NAA 10.7 μM + FDP 3 μM with FW/DW: 50/28 g. Two different Agrobacterium rhizogenes strains (A₄ and R₁₀₀₀) were evaluated for HR induction. The biomass of HRs induced using half-strength MS + B₅ vitamins with 3 μM FDP was FW/DW: 40/20 g and FW/DW: 41/19 g, respectively. To determine β-caryophyllene accumulation, we have isolated the essential oil from FDP-treated calli and HRs and quantified β-caryophyllene using gas chromatography-mass spectrometry (GC-MS). The highest production of β-caryophyllene was noticed in HR cultures induced using A₄ and R₁₀₀₀ strains on half-strength MS medium containing 3 μM FDP, which produced 2.92 and 2.80 mg/ml β-caryophyllene, respectively. The optimized protocol can be used commercially by scaling up the production of a β-caryophyllene compound in a short span of time.

Antioxidant activity, extraction and application of psyllium mucilage in chocolate drink

Purpose

The purpose of this study is to extract psyllium mucilage and evaluate its antioxidant compounds (in the best extraction condition) and its application in a chocolate drink.

Design/methodology/approach

First, the extraction by ultrasonic bath was evaluated, followed by water bath extraction, and as there was no difference between the methods, a water bath experimental design was carried out to evaluate the best extraction conditions for psyllium mucilage, having response variables, yield and emulsion stability. A chocolate drink with psyllium mucilage was produced and evaluated in the best extraction condition to compare with xanthan gum.

Findings

The best extraction conditions for psyllium mucilage were 60°C for 2 h and 1:80 ratio (seed:water). It can be verified that psyllium is rich in antioxidant compounds (0.71 mg GAE/g and 6.67 Mmol ET/g by 2,2′-azinobis (3-ethylbenzthiazoline sulfonic acid-6), and 9.65 Mmol ET/g for ferric reducing antioxidant power), which can greatly contribute to its application in food products. The use of mucilage in chocolate drink is feasible, as among its several attributes there was no significant difference between samples, highlighting texture attributes in which mucilage samples did not differ from the control containing xanthan gum (being the grades approximated 6.84).

Originality/value

Psyllium presented several antioxidant compounds that are very desirable in food products. In the chocolate drink, psyllium mucilage showed potential use as a thickener, so it is important for further studies to improve the product’s development, but it is currently feasible to be produced in an industrial scale.

Metabolic profiling and scavenging activities of developing circumscissile fruit of psyllium (Plantago ovata Forssk.) reveal variation in primary and secondary metabolites

BACKGROUND

Developing fruit is considered as an excellent model to study the complex network of metabolites which are altered rapidly during development.

RESULTS

Metabolomics revealed that developing psyllium fruit is a rich source of primary metabolites (ω-3 and ω-6 fatty acids and amino-acids), secondary metabolites and natural antioxidants. Eidonomy and anatomy confirmed that psyllium fruit followed five stages of development. Total lipids and fatty acids were synthesized differentially; saturated fatty acids (FAs) increased, whereas total polyunsaturated FAs decreased with increasing developmental stage. The unsaturation index and degree of unsaturation showed a catenary curve. Principal component analysis confirmed a significant shift in the FA profile from bud initiation to the maturation stage. Similarly, a similar level of total amino acids was present at different developmental stage following a temporal biosynthesis pathway. Total phenolic and flavonoid contents decreased in tandem with fruit development. Twenty-two different metabolites were identified, and metabolic changes were also observed during fruit development. Six metabolites were detected exclusively in the flowering stage, whereas two were detected in each of early and maturity stages of development. The metabolites apigenin and kaempferol were detected ubiquitously in all developmental stages. Time-dependent metabolomics revealed a shift in metabolite biosynthesis.

CONCLUSION

During fruit development, metabolites, FAs, amino acids, total phenolics, total flavonoids, antioxidants and scavenging activities changed progressively and were co-ordinately linked to each other. As a future perspective, further studies will focus on the validation of identified metabolites, which integrated with transcriptomics data and will reveal the metabolic regulatory network of development psyllium fruit.

Chemical composition and bioactive properties of byproducts from two different kiwi varieties

Kiwis are an example of fruits with excellent bioactive properties worldwide appreciated and consumed generating tons of waste. Thus, the objective of this work was to compare two varieties of kiwi: Actinidia deliciosa cv. "Hayward" (green) and Actinidia spp. (red) regarding the nutritional value of their pulps, chemical composition and bioactivities of each pulp and peel. The results revealed that pulps have a high water content and low amount of other macronutrients. Both parts of red kiwi presented the highest tocopherols content and red kiwi pulp presented the highest content in ascorbic acid. In general, the peels exhibited the highest antioxidant activity and green kiwi peels showed cytotoxicity and anti-inflammatory activity, which could be related to its higher content in phenolic compounds, especially B-type (epi)catechin dimer. Therefore, kiwi components currently underutilized may be indicated as a source of natural functionalizing ingredients with several benefits for human health.

Enhanced production of podophyllotoxin, kaempferol, and quercetin from callus culture of Dysosma pleiantha (Hance) Woodson: An endangered medicinal plant

Dysosma pleiantha (Hance) Woodson is one of the endangered traditional Chinese medicinal herbs, highly valued for its medicinal properties by Taiwan's mountain tribes. The present study aims to develop an efficient protocol for callus biomass by optimizing suitable culture medium, carbon source culture condition, and enhanced production of pharmaceutically important podophyllotoxin, kaempferol, and quercetin from callus culture of D. pleiantha under the influence of different additives. Best callus induction was achieved in Gamborg's medium (B5) with 1 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) along with 0.2 mg/L kinetin under dark condition. Tender leaves of D. pleiantha showed the maximum of 86% callus induction among the different explants tested. Highest leaf callus proliferation was noted in B5 medium with 1 mg/L 2,4-D incubated under complete darkness. In addition, it was found that B5 medium with 1 mg/L 2,4-D along with 2 g/L peptone produced more leaf callus biomass and enhanced production of podophyllotoxin (16.3-fold), kaempferol (12.39-fold), and quercetin (5.03-fold) compared to control. Therefore, D. pleiantha callogenesis can provide an alternative source for enhanced production of secondary compounds regardless of the exploitation of its natural plant population.

Biochemical profile and in vitro biological activities of extracts from seven folk medicinal plants growing wild in southern Tunisia

Recently, much attention has been paid to the extracts obtained from plant species in order to analyse their biological activities. Due to the climate diversity in Tunisia, the traditional pharmacopoeia consists of a wide arsenal of medicinal plant species since long used in folk medicine, in foods as spices, and in aromatherapy. Although many of these species are nearly facing extinction, only a small proportion of them have been scientifically studied. Therefore, this study explores the biochemical properties of seven spontaneous plants, which were harvested in the arid Tunisian desert: Marrubium vulgare (L.), Rhus tripartita (Ucria) D.C., Thymelaea hirsute (L.) Endl., Plantago ovata (Forsk.), Herniaria fontanesii (J. Gay.), Ziziphus lotus (L.) and Hyoscyamus albus (L.). Extracts from these plants were found to contain different types of secondary metabolites (polyphenols, flavonoids, condensed tannins, crude saponins, carotenoids and alkaloids) that are involved in important biological activities. The biological activity of the extracts obtained from each Tunisian plant was assessed: first of all, leukaemia and colon cancer cell lines (K-562 and CaCo-2 respectively) were treated with different concentrations of extracts, and then the anti-proliferative activity was observed. The results showed, in particular, how the plant extract from Rhus tripartita significantly inhibits cell proliferation, especially on the K-562 tumour cell line. Subsequently, the anti-inflammatory activity was also assessed, and the results showed that Herniaria fontanesii and Marrubium vulgare possess the highest activity in the group of analysed plants. Finally, the greatest acetylcholinesterase inhibitory effect was exhibited by the extract obtained from Rhus tripartita. In conclusion, all the Tunisian plants we analysed were shown to contain a remarkable amount of different bio-active compounds, thus confirming their involvement in several biological activities. Rhus tripartita and Ziziphus lotus were shown to be particularly effective in anti-proliferative activity, while Herniaria fontanesii were shown to have the best anti-inflammatory activity.

Chromium (VI) - induced stress response in the plant Plantago ovata Forsk in vitro

Background

Plants experience severe physiological stress from heavy metal pollution caused by improper discarding of the industrial wastes. Hexavalent chromium [Cr (VI)] is one of the major heavy metal pollutants in India and is present particularly in some regions where Plantago ovata grows to a great extent. This study was aimed at finding the effects of Cr (VI) on P. ovata and manoeuvres of the plant to combat such heavy metal exposure in vitro.

Methods

Potassium dichromate was used as a source of Cr (VI) to induce the heavy metal stress. Range of Cr (VI) sublethal doses [0 mM (control), 0.1 mM, 0.3 mM, 0.5 mM, 1 mM, 1.5 mM and1.8 mM] was used to observe its effect on the plant. The seeds of the plant were grown on sucrose-agar media with different concentrations of potassium dichromate, and ten-day old seedlings were then harvested and examined.

Results

The germination rate reduced below 50% at 1.9 mM Cr (VI) concentration and thus, 0 mM–1.8 mM concentration ranges were found to be suitable for sublethal dose. Morphological changes namely, reduction of the shoot-root length and multiple root development were caused by Cr (VI) in a dose-dependent manner. The plant showed elevated responses against Cr (VI), up to 1.5 mM (10 days treated) in terms of increasing accumulation of secondary metabolites like polyphenols, chlorophyll content (chlorophyll a, b and total chlorophyll), carotenoids and total antioxidant activity. DPPH radical scavenging activity along with malondialdehyde (MDA) content was not significantly elevated with the increase in Cr (VI) concentration indicating that the lipid peroxidation rate within the tissue was low. Phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO) gene expressions were upregulated by 1 mM Cr (VI) concentration, which decreased at higher concentrations. The atomic absorption spectroscopy analysis also showed significant accumulation of Cr (VI) in the shoot and root with an increase in the potassium dichromate concentration.

Conclusion

Cr (VI) reduced the shoot-root length and seed germination in a dose-dependent manner. The plant system tried to combat the Cr (VI) stress by upregulating the stress response genes in the phenylpropanoid pathway along with an increase in polyphenol and antioxidant contents, which were evident from the lowering of lipid peroxidation rate and increase in PAL and PPO gene expressions.

Electronic supplementary material

The online version of this article (10.1186/s41021-018-0109-0) contains supplementary material, which is available to authorized users.

The GhmiR157a-GhSPL10 regulatory module controls initial cellular dedifferentiation and callus proliferation in cotton by modulating ethylene-mediated flavonoid biosynthesis

MicroRNAs (miRNAs) modulate many biological processes through inactivation of specific mRNA targets such as those encoding transcription factors. A delicate spatial/temporal balance between specific miRNAs and their targets is central to achieving the appropriate biological outcomes. Somatic embryogenesis in cotton (Gossypium hirsutum), which goes through initial cellular dedifferentiation, callus proliferation, and somatic embryo development, is of great importance for both fundamental research and biotechnological applications. In this study, we characterize the function of the GhmiR157a-GhSPL10 miRNA-transcription factor module during somatic embryogenesis in cotton. We show that overexpression of GhSPL10, a target of GhmiR157a, increases free auxin and ethylene content and expression of associated signaling pathways, activates the flavonoid biosynthesis pathway, and promotes initial cellular dedifferentiation and callus proliferation. Inhibition of expression of the flavonoid synthesis gene F3H in GhSPL10 overexpression lines (35S:rSPL10-7) blocked callus initiation, while exogenous application of several types of flavonol promoted callus proliferation, associated with cell cycle-related gene expression. Inhibition of ethylene synthesis by aminoethoxyvinylglycine treatment in the 35S:rSPL10-7 line severely inhibited callus initiation, while activation of ethylene signaling through 1-aminocyclopropane 1-carboxylic acid treatment, EIN2 overexpression, or inhibition of the ethylene negative regulator CTR1 by RNA interference promoted flavonoid-related gene expression and flavonol accumulation. These results show that an up-regulation of ethylene signaling and the activation of flavonoid biosynthesis in GhSPL10 overexpression lines were associated with initial cellular dedifferentiation and callus proliferation. Our results demonstrate the importance of a GhmiR157a-GhSPL10 gene module in regulating somatic embryogenesis via hormonal and flavonoid pathways.

Experimental Paper. In vitro synthesis of mucilage in Plantago ovata Forsk affected by genotypes and culture media

Introduction: Psyllium (Plantago ovata Forsk) is medicinally used mainly for its mucilage content. Objective: In the present study, an attempt was made to improve mucilage yield under in vitro callus culture using different genotypes, explants and culture media. Methods: The effects of a range of concentrations of plant growth regulators including 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin (Kin) were evaluated on mucilage synthesis under in vitro culture using cotyledon, hypocotyl and seed explants. Fourteen genotypes originating from different geographical regions of Iran were used to evaluate their response to in vitro mucilage synthesis. Results: The highest rate of callus induction (76%) and callus growth rate CGR (0.38 mm/day) were induced on MS medium supplemented with 0.5 mg/l 2,4-D and 1 mg/l Kin and the hypocotyl explant. The results of analysis of variance showed significant genotypic differences for callus induction, CGR and mucilage content of callus and seeds. The mucilage content ranged from 0.38 to 0.08 (g/g DW) and 0.13 to 0.042 (g/g DW) for callus and seed, respectively. The superior callus induction (73%), CGR (0.45 mm/day) and mucilage content of callus (0.38 g/g DW) was denoted to Po1 genotype. The callus produced nearly three times more mucilage than the seeds using superior genotype (Po1). Conclusion: The results of this study revealed that high efficiency of callus culture of P. ovata using hypocotyl explant accompanied by the exploration of genetic diversity are important to improve the yield of mucilage synthesis by in vitro callus culture.

Differences in glycosyltransferase family 61 accompany variation in seed coat mucilage composition in Plantago spp

Xylans are the most abundant non-cellulosic polysaccharide found in plant cell walls. A diverse range of xylan structures influence tissue function during growth and development. Despite the abundance of xylans in nature, details of the genes and biochemical pathways controlling their biosynthesis are lacking. In this study we have utilized natural variation within the Plantago genus to examine variation in heteroxylan composition and structure in seed coat mucilage. Compositional assays were combined with analysis of the glycosyltransferase family 61 (GT61) family during seed coat development, with the aim of identifying GT61 sequences participating in xylan backbone substitution. The results reveal natural variation in heteroxylan content and structure, particularly in P. ovata and P. cunninghamii, species which show a similar amount of heteroxylan but different backbone substitution profiles. Analysis of the GT61 family identified specific sequences co-expressed with IRREGULAR XYLEM 10 genes, which encode putative xylan synthases, revealing a close temporal association between xylan synthesis and substitution. Moreover, in P. ovata, several abundant GT61 sequences appear to lack orthologues in P. cunninghamii. Our results indicate that natural variation in Plantago species can be exploited to reveal novel details of seed coat development and polysaccharide biosynthetic pathways.

Non-targeted Metabolite Profiling and Scavenging Activity Unveil the Nutraceutical Potential of Psyllium (Plantago ovata Forsk)

Non-targeted metabolomics implies that psyllium (Plantago ovata) is a rich source of natural antioxidants, PUFAs (ω-3 and ω-6 fatty acids) and essential and sulfur-rich amino acids, as recommended by the FAO for human health. Psyllium contains phenolics and flavonoids that possess reducing capacity and reactive oxygen species (ROS) scavenging activities. In leaves, seeds, and husks, about 76, 78, 58% polyunsaturated, 21, 15, 20% saturated, and 3, 7, 22% monounsaturated fatty acids were found, respectively. A range of FAs (C12 to C24) was detected in psyllium and among different plant parts, a high content of the nutritive indicators ω-3 alpha-linolenic acid CPS (57%) and ω-6 linoleic acid CPS (18%) was detected in leaves. Similarly, total content of phenolics and the essential amino acid valine were also detected utmost in leaves followed by sulfur-rich amino acids and flavonoids. In total, 36 different metabolites were identified in psyllium, out of which 26 (13 each) metabolites were detected in leaves and seeds, whereas the remaining 10 were found in the husk. Most of the metabolites are natural antioxidants, phenolics, flavonoids, or alkaloids and can be used as nutrient supplements. Moreover, these metabolites have been reported to have several pharmaceutical applications, including anti-cancer activity. Natural plant ROS scavengers, saponins, were also detected. Based on metabolomic data, the probable presence of a flavonoid biosynthesis pathway was inferred, which provides useful insight for metabolic engineering in the future. Non-targeted metabolomics, antioxidants and scavenging activities reveal the nutraceutical potential of the plant and also suggest that psyllium leaves can be used as a green salad as a dietary supplement to daily food.