Accumulation Of Bioactive Compounds Research Articles

Application of UV-B radiation for enhancing the accumulation of bioactive phenolic compounds in pigeon pea [Cajanus cajan (L.) Millsp.] hairy root cultures.

UV-B radiation is an ideal elicitation strategy for promoting phytochemical accumulation in plant in vitro cultures, associated with various advantages of easy manipulation, cost-effectiveness, no residue, and instantaneous termination. For the first time, UV-B radiation was used to enhance the production of bioactive phenolic compounds (flavonoids and stilbenes) in pigeon pea hairy root cultures (PPHRCs). The total yield of eight flavonoids (414.95±50.68μg/g DW) in 42-day-old PPHRCs exposed to 4h of UV-B radiation increased by 1.49-fold as against control, whereas the yield of cajaninstilbene acid (6566.01±702.14μg/g DW) in PPHRCs undergoing 10h of UV-B radiation significantly increased by 2.31-fold over control. UV-B radiation was found to induce the oxidative stress in PPHRCs and cause the tissue damage to hairy roots, which improved the levels of endogenous salicylic acid thus triggering the expression of genes involved in phenylpropanoid biosynthesis pathway. And, a regulation competition in metabolic flow dominated by CHS and STS was responsible for the difference in accumulation trends of flavonoids and cajaninstilbene acid. Results of this study not only provide a feasible and simple UV-B supplementation strategy for the enhanced production of bioactive phenolic compounds (especially the high-value cajaninstilbene acid) in PPHRCs, but also contributed to the understanding of photobiological responses related to secondary metabolism.

Genetic and seasonal variability of bioactive polyphenolic compounds and antioxidant‐based phytonutrient promise of diverse vegetable amaranths of Indo‐Gangetic plains of West Bengal

AbstractBackgroundThough vegetable amaranths harbor good pool of phenolic compounds, but till date, there is no systematic database on seasonal and genetic diversity based antioxidant‐dependent phytonutrient promise of amaranths of Gangetic plains of West Bengal particularly those derived from chalcone and cinnamic acids of phenyl propanoid metabolism and hence is the subject of present investigation.ResultsA comparative evaluation based on RP‐HPLC (Reverse Phase‐High Performance Liquid Chromatography) coupled photodiode assay of twenty one pharmacologically important bioactive polyphenolic compounds (flavonoids and phenolic acids) along with sensitive biomarkers of antioxidant properties (reducing property, metal chelating property, superoxide radical scavenging property, hydroxyl radical scavenging property, antilipid peroxidation, anti‐inflammatory property, and antidiabetic property) has been done for the assessment of genotype‐based seasonal variation of antioxidant‐based phytonutrient promise of vegetable amaranths of Indo‐Gangetic plains of West Bengal. The work exhibited genotype‐specific accumulation of bioactive polyphenolic compounds and associated antioxidant properties, with A. hypochondriacus L. exhibiting significantly greater abundance of majority of polyphenolic compounds tested, followed by A. viridis L. and A. hybridus L. The work also recorded the genotype‐specific seasonal elicitation of the synthesis of bioactive polyphenolic compounds.ConclusionTaken as a whole, the work suggests genotype‐specific seasonal variations in the accumulation of bioactive polyphenolic compounds and antioxidant‐based phytonutrient promise in diverse amaranth germplasms of Gangetic plain of West Bengal and identified lead germplasms as low‐cost antioxidant supplement for utilization in crop diversification program.

Effect of stress on germination of djulis (Chenopodium formosanum Koidz.) sprouts: a natural alternative to enhance the betacyanin and phenolic compounds.

Germination is regarded as a natural method for improving the bioavailability of seed nutrients against stress, which enhances the accumulation of bioactive compounds. The present study aimed to determine the effect of stress (H2 O2 , catechin, gallic acid, tyrosine, and NaCl) during germination of djulis (Chenopodium formosanum Koidz.) sprouts on betacyanin, phytochemicals, and antioxidant capacities. The betacyanin and antioxidant activities of the djulis sprouts increased significantly compared to seeds. The lowest betacyanin was found in NaCl-stressed sprouts. The djulis sprouts reported the presence of celosianins I and II (50.72%), which was absent in seeds. Hydroxycinnamic acids accounted for > 60% of the total phenolic compounds in sprouts, whereas rutin predominated in the seeds. Germination under stress may represent an effective natural method for improving the bioactive potential of sprouts, an alternative to use seeds, in the development of bioactive compounds-enriched healthy foods that are good for public health. © 2022 Society of Chemical Industry.

Brassica sprouts exposed to microplastics: Effects on phytochemical constituents

Microplastics (MPs) can affect plant biomass, tissue composition, and root traits. However, the effects of MPs on the synthesis of secondary metabolites and on the accumulation of bioactive compounds remain poorly studied. The objective of this work was to analyze accumulation of bioactive compounds in broccoli and radish sprouts grown hydroponically in a substrate containing seven different toxic amounts (from very low to extremely high) of low-density polyethylene (PE). Radish was more severely affected by microplastic pollution than broccoli. The effect on the phytochemical composition was statistically significant in both species compared to control. In this aspect, glucosinolate (GSL) content was negatively affected by MPs decreasing from 182 to 124 mg 100 g−1 at medium doses of MPs in broccoli, whereas these compounds drastically decreased from 253 to 151 mg 100 g−1 at the same doses in radish. Anthocyanin content significantly increased until medium doses of MPs ranging from 6.28 to 11.44 mg 100 g−1 in broccoli whereas in radish was from 2.44 to approximately 4 mg 100 g−1. In addition, other morphological and physiological parameter were considered. The analysis of malondialdehyde (MDA) showed significant effects on broccoli and radish in all the MP treatments. The results revealed that high loads of MPs in the substrate affect growth parameters, lipid peroxidation rate estimated by MDA, and phytochemicals of broccoli and radish sprouts, with differences in response to MPs pollution and intensity between species.

Enhancement of Antioxidant Activity and Bioactive Compounds in Eggplants Using Postharvest LEDs Irradiation

Eggplant (Solanum melongena L.), one of the major vegetable crops, is recognized for its availability of numerous bioactive compounds and antioxidant activity. The accumulation of these compounds in plant tissues can be increased by exogenous stimuli, including light exposure. This study aimed at enhancing the antioxidant activity and bioactive compounds of eggplant using light-emitting diode (LEDs) irradiation after harvest. For this purpose, eggplant fruits were irradiated under LEDs at different wavelengths, including red (650–660 nm), blue (450–460 nm), or the combination of red and blue (red + blue) LEDs, for 48 h. The results indicated that red + blue LED exposure during postharvest significantly (p < 0.05) elevated the accumulation of bioactive compounds and antioxidant activity. The accumulation of major phenolic compounds, chlorogenic acid (58.59 mg/100 g FW), and gallic acid (14.25 mg/100 g FW) in the eggplant fruits was increased significantly under red + blue irradiation when compared with the control (under dark condition). The total phenolic (821.86 mg GAE/100 g FW) and the total flavonoid (595.98 mg CE/100 g FW) contents were shown to have a considerably high accumulation in the peels of eggplant after irradiation under red + blue LEDs, whereas the total carotenoid content was relatively high in the flesh of eggplant fruits. Consequently, red + blue LED irradiation can be considered as a convenient tool used for the postharvest of eggplant, with a positive effect in the increasing of important secondary metabolites. The obtained eggplant fruits proved to be a promising source of bioactive and antioxidant compounds for functional food production.

Review on effect of postharvest illumination by fluorescent and ultraviolet light waves on the quality of vegetables

AbstractPostharvest illumination is an emerging nonthermal preservation technique used to preserve the quality of vegetables. This review aimed to provide an insight into the effect, importance, and limitations of postharvest illumination by fluorescent and ultraviolet (UV) light on the physical and nutraceutical properties of vegetables. It presents the current information on the postharvest application of these two lightings based on the vegetable species. According to the existing studies, both photoperiod and continuous (low‐intensity) fluorescent lighting treatments were beneficial more toward preserving the quality (delaying senescence and deterioration) of postharvest vegetables, mainly leafy vegetables. However, inconsistent results are also possible with the light quality (intensity and duration) on the postharvest fluorescent lighting treatment. According to gathered information, both UV‐B and UV‐C postharvest irradiation has been beneficial in delaying senescence and chlorophyll degradation and inducing bioactive compounds accumulation in some vegetable species. UV‐C application is appeared to have a relatively steady effect on the postharvest storage of vegetables. But UV‐B irradiation effect on the postharvest quality of vegetables was appeared to be dose dependent and not stable. In conclusion, it is important to consider vegetable (species, cultivar, harvesting age, and intact or fresh‐cut), previous treatments/conditions, optimum postharvest lighting condition (illumination source, dose, intensity, and duration), and the storage condition (temperature and relative humidity) for a successful implementation of postharvest illumination. More research is required to explore the postharvest application of fluorescent and UV (UV‐A, UV‐B, UV‐C) irradiation on vegetables.Practical ApplicationsMultiple research approaches have been taken to preserve the postharvest quality of vegetables while minimizing chemical preservation techniques. Postharvest illumination is a nonchemical preservation technique that has attained more interest due to the advantages it holds, such as being highly efficient and residue‐free. Fluorescent and UV lighting on harvested leafy and non‐leafy vegetables are beneficial in delaying senescence and chlorophyll degradation, preserving nutritional quality, and extending the shelf life. With the accessibility of more research data and innovative strategies, the future of postharvest illumination of fluorescent and UV maybe steer toward implementation on commercial scale vegetable production (e.g., during storage and/or transportation).

Growth, bioactive compound accumulation and antioxidant activity in rhizomes and storage roots of Boesenbergia rotunda (L.) Mansf.

Growth, bioactive compound accumulation and antioxidant activity in rhizomes and storage roots of Boesenbergia rotunda (L.) Mansf.

Traditional in vitro strategies for sustainable production of bioactive compounds and manipulation of metabolomic profile in medicinal, aromatic and ornamental plants.

Precursor feeding, elicitation and culture medium parameters are traditional in vitro strategies to enhance bioactive compounds of medicinal, aromatic, and ornamental plants (MAOPs). Machine learning can help researchers find the best combination of these strategies to increase the secondary metabolites content of MAOPs. Many requirements for human life, from food, pharmaceuticals and cosmetics to clothes, fuel and building materials depend on plant-derived natural products. Essential oils, methanolic and ethanolic extracts of in vitro undifferentiated callus and organogenic cultures of medicinal, aromatic, and ornamental plants (MAOPs) contain bioactive compounds that have several applications for various industries, including food and pharmaceutical. In vitro culture systems provide opportunities to manipulate the metabolomic profile of MAOPs. Precursors feeding, elicitation and culture media optimization are the traditional strategies to enhance in vitro accumulation of favorable bioactive compounds. The stimulation of plant defense mechanisms through biotic and abiotic elicitors is a simple way to increase the production of secondary metabolites in different in vitro culture systems. Different elicitors have been applied to stimulate defense machinery and change the metabolomic profile of MAOPs in in vitro cultures. Plant growth regulators (PGRs), stress hormones, chitosan, microbial extracts and physical stresses are the most applied elicitors in this regard. Many other chemical tolerance-enhancer additives, such as melatonin and proline, have been applied along with stress response-inducing elicitors. The use of stress-inducing materials such as PEG and NaCl activates stress tolerance elicitors with the potential of increasing secondary metabolites content of MAOPs. The present study reviewed the state-of-the-art traditional in vitro strategies to manipulate bioactive compounds of MAOPs. The objective is to provide insights to researchers involved in in vitro production of plant-derived natural compounds. The present review provided a wide range of traditional strategies to increase the accumulation of valuable bioactive compounds of MAOPs in different in vitro systems. Traditional strategies are faster, simpler, and cost-effective than other biotechnology-based breeding methods such as genetic transformation, genome editing, metabolic pathways engineering, and synthetic biology. The integrate application of precursors and elicitors along with culture media optimization and the interpretation of their interactions through machine learning algorithms could provide an excellent opportunity for large-scale in vitro production of pharmaceutical bioactive compounds.

Elicitation enhanced the production of bioactive compound and biomass accumulation in callus cultures of Glycyrrhiza glabra L.

Elicitation enhanced the production of bioactive compound and biomass accumulation in callus cultures of Glycyrrhiza glabra L.

Integrative analyses of targeted metabolome and transcriptome of Isatidis Radix autotetraploids highlighted key polyploidization-responsive regulators

BackgroundIsatidis Radix, the root of Isatis indigotica Fort. (Chinese woad) can produce a variety of efficacious compound with medicinal properties. The tetraploid I. indigotica plants exhibit superior phenotypic traits, such as greater yield, higher bioactive compounds accumulation and enhanced stress tolerance. In this study, a comparative transcriptomic and metabolomic study on Isatidis Radix autotetraploid and its progenitor was performed.ResultsThrough the targeted metabolic profiling, 283 metabolites were identified in Isatidis Radix, and 70 polyploidization-altered metabolites were obtained. Moreover, the production of lignans was significantly increased post polyploidization, which implied that polyploidization-modulated changes in lignan biosynthesis. Regarding the transcriptomic shift, 2065 differentially expressed genes (DEGs) were identified as being polyploidy-responsive genes, and the polyploidization-altered DEGs were enriched in phenylpropanoid biosynthesis and plant hormone signal transduction. The further integrative analysis of polyploidy-responsive metabolome and transcriptome showed that 1584 DEGs were highly correlated with the 70 polyploidization-altered metabolites, and the transcriptional factors TFs-lignans network highlighted 10 polyploidy-altered TFs and 17 fluctuated phenylpropanoid pathway compounds.ConclusionsThese results collectively indicated that polyploidization contributed to the high content of active compounds in autotetraploid roots, and the gene–lignan pathway network analysis highlighted polyploidy–responsive key functional genes and regulators.

Unraveling the Modulation of Controlled Salinity Stress on Morphometric Traits, Mineral Profile, and Bioactive Metabolome Equilibrium in Hydroponic Basil

Salinity is a major concern in several ecosystems and has a significant impact on global agriculture. To increase the sustainability of horticultural food systems, better management and usage of saline water and soils need to be supported by knowledge of the crop-specific responses to tolerable levels of salinity. The aim of this work was to study the effects of mild salinity on morphological growth and development, leaf color, mineral composition, antioxidant activities, and phenolic profile of sweet basil (Ocimum basilicum L.). Plants grew in hydroponics and were exposed to three nutrient solutions (NSs) differing in the NaCl concentration (either 0, 20, or 40 mM). Inhibitory effects on leaf area, fresh yield, and shoot biomass were evident starting from the lowest NaCl concentration, and they became more severe and wide-ranging at 40 mM, also affecting height and root-to-shoot ratio. Salinity increased the nutritional quality in terms of antioxidant activity and polyphenols in leaves, with a reduction in macroelements at 40 mM NaCl. Moreover, the two mild NaCl concentrations specifically modified the concentration of various phenolic acids in leaves. Overall, the use of a slightly saline (20 mM) NS could be tolerated by basil in hydroponics, strongly ameliorating the nutritional profile in the face of relative yield loss. Considering the significantly higher accumulation of bioactive compounds, our work implies that the use of low-salinity water can sustainably increase the nutritional value and the health-promoting features of basil leaves.

Effects of calcium chloride treatment on bioactive compound accumulation and antioxidant capacity in germinated brown rice

In this study, the effects of calcium chloride on bioactive compound accumulation and antioxidant capacity were investigated in germinated brown rice. Brown rice treated with CaCl2 (50–200 mM) during germination showed higher accumulation of bioactive compounds such as polyphenols, flavonoids, and γ-aminobutyric acid in a concentration-dependant manner. These results were associated with activation of bioactive compound-triggering enzymes such as glutamate decarboxylase and phenylalanine ammonia-lyase compared to ungerminated or CaCl2-untreated germinated brown rice. Furthermore, CaCl2 treatment in germinated brown rice significantly enhanced its antioxidant capacity, including reducing power and free radical scavenging activity, and considerably improved the cell viability up to 92.83% against hydrogen peroxide-mediated cell damage and oxidative stress in C2C12 myoblast cells. Cellular generation of ROS and depletion of reduced form of glutathione (GSH) were significantly reduced by CaCl2-treated germinated brown rice. These findings suggest that CaCl2 treatment during germination of brown rice is an effective strategy to improve its nutritional value and health-promoting properties.

Effects of application of organic formulated fertiliser and composted Tithonia diversifolia leaves on the growth, yield and quality of okra

ABSTRACT The production of healthy food in a sustainable manner is a major challenge for agriculture. Pot experiments were conducted in an open field during the rainy season in 2017 and 2018 to study the effects of the application of composted leaves of Tithonia diversifolia (T) and organo-biodegradable (OBD+) formulated fertiliser on growth, yield and concentrations of minerals and bioactive compounds in okra. Treatments consisted of four application rates of composted Tithonia leaves (0, 10, 20 and 30 g 10 kg−1 soil) and three rates of organic-biodegradable (OBD+) formulated fertiliser (0, 10 and 20 g 10 kg−1 soil), which were combined and arranged in a complete randomised design with four replications. Performance and quality parameters of okra were measured. The application of the amendments significantly increased vegetative growth and yield parameters of okra, compared with the control, with the application of 30 T + 10 OBD+ resulting in the highest values for growth and yield. The number of days to flowering and fruiting of the okra was significantly reduced by the application of the organic amendments. The results also revealed that the concentrations of mineral elements and bioactive compounds in the okra fruits significantly increased with applications of 30 T + 20 OBD + and 30 T + 10 OBD +. Therefore, for improved vegetative and yield performance as well as accumulation of mineral elements and bioactive compounds, the application of 30 T + 10 OBD+ was considered as the most suitable for the cultivation of okra in the study area.

Postharvest UV-B radiation increases enzyme activity, polysaccharide and secondary metabolites in honeysuckle (Lonicera japonica Thunb.)

Postharvest ultraviolet-B (UV-B) radiation can modulate the accumulation of bioactive compounds with many pharmacological effects in plants. Honeysuckle (Lonicera japonica Thunb.) is a UV-B tolerant crop which has a high medical value. The effects of UV-B on bioactive compounds in its flowers have been reported, while very few studies focused on the leaves and stems. Therefore, the effects of postharvest UV-B radiation on basic physiological traits and bioactive compounds (polysaccharides and secondary metabolites) in the leaves, stems and flowers of honeysuckle were investigated in this study. In this study, the leaves, stems and flowers of honeysuckle were exposed to UV-B radiation (0, 8.4 and 22.4 μW cm−2) for different times (2, 4, 6 and 8 h), and variables were detected after 24 h after they were able to get a repair time. The results showed that the contents of chlorophyll, carotenoid, soluble sugar, and the activities of catalase (CAT) and superoxide dismutase (SOD) in postharvest leaves were increased after UV-B treatment. But the malonaldehyde (MDA) content in leaves decreased when the duration of UV-B treatment lasted for 4 h. Besides, the contents of polysaccharide, total polyphenols, total flavonoid, and chlorogenic acid in different organs all increased significantly and reached a peak under the UV-B1 (8.4μW cm−2) treatment for 2 h, whereas they reached the lowest point under the 6 h of UV-B2 (22.4μW cm−2) exposure according to the heat map analysis. Interestingly, the Pearson correlation analysis revealed that the total flavonoid content was positively correlated with the chlorogenic acid content in the flowers of honeysuckle, and the total flavonoid content was negatively correlated with the contents of chlorophyll, CAT and carotenoid in plant leaves. In a word, the secondary metabolites and polysaccharide of honeysuckle can be increased by postharvest UV-B, and the quality can be improved by adjusting its physiological traits. In addition, the content of bioactive substances is correlated with the physiological traits. The results will provide a basis for improving the medicinal values of honeysuckle by postharvest UV-B treatment.

A new approach for cultivating the cyanobacterium Nostoc calcicola (MACC-612) to produce biomass and bioactive compounds using a thin-layer raceway pond

The culture of microalgae and cyanobacteria in open systems has been improved through the novel approach of thin-layer raceway ponds. The importance of studying mass cultivation of the cyanobacterium Nostoc calcicola (further as Nostoc) lies in its biotechnological potential as a source of bioactive compounds for food and non-food applications. These compounds include polysaccharides, mycosporine-like amino acids and phycocyanin. Nostoc was cultured outdoors in a thin-layer raceway pond where the biomass production, physiological status, photosynthetic activity, and biochemical composition were monitored through the experimental period of 5 days. The biomass, as did the maximal quantum yield of PSII, maximal electron transport rate (ETRmax) and photosynthetic efficiency (αETR) increased throughout the experimental period showing the optimal operation of the thin-layer raceway ponds, due to the light penetrates deeper into the thin culture layer and thus more light is available to the cells. Oxygen levels in the culture increased over time, but no photoinhibition was evident indicating optimal action of non-photochemical mechanisms. Nostoc increased the total internal carbon content over the experimental period. Chlorophyll increased, whereas the N compounds such as the biliprotein phycocyanin decreased. Among the UV-absorbing compounds, polyphenols, mycosporine-like amino acids, such as shinorine and other unknown UV-A absorbing compounds were detected. There components showed a positive correlation to antioxidant activity. Thus, the optimal accumulation of biomass and the accumulation of bio-active compounds having antioxidant capacity show the possible biotechnological applications of Nostoc.

Variations in the leaf metabolite profile between hydroponic and field grown Moringa oleifera Lam. genotypes

Medicinal and herbal plants are increasingly cultivated on commercial scale all around the world, to satisfy the large demand for natural remedies associated with plant bioactive compounds. Moringa oleifera Lam. is one of these attractive plant species, being cultivated across the world, with most of the production in Africa and Asia. However, it is increasingly reported that the composition and concentration of bioactive compounds in medicinal plants, are largely influenced by factors such as the growing environment, harvesting time, and climatic factors among others. The aim of this study was therefore to determine the differences in the leaf metabolite profile between hydroponic and field grown M. oleifera plants due to cultivation system, harvesting time and genotypes. 1H NMR was used for data acquisition, and MestReNova software was used for the pre-processing of the spectral data. Multivariate data analysis by means of PCA and OPLS-DA was conducted, followed by targeted metabolite analyses. The results show variations in the leaf metabolite profile as influenced by cultivation systems, harvesting time and genotypes. In both PKM-1 and Malawi hybrid genotypes, the concentration level of chlorogenic acid, ferulic acid, vanillic acid, and wogonin compounds were higher in the hydroponic leaf material, whereas the concentration level of esculetin, niazirin and GABA were slightly higher in the field harvested leaf materials. With regards to harvesting time effect, the concentration level of all seven targeted compounds were higher in February (summer) harvest as compared to May (autumn) harvest. Among the genotypes, PKM-1 showed to have higher concentration of certain targeted compounds as compared to Malawi hybrid, but on the other hand certain compounds from the Malawi hybrid showed also higher concentrations. These results provide insight on the possible alternative production system that can be adopted to optimise and improve accumulation of bioactive compounds in M. oleifera leaf materials.

Recent Advances toward the Application of Non-Thermal Technologies in Food Processing: An Insight on the Bioaccessibility of Health-Related Constituents in Plant-Based Products.

Fruits and vegetables are rich sources of bioactive compounds and micronutrients. Some of the most abundant are phenols and carotenoids, whose consumption contributes to preventing the occurrence of degenerative diseases. Recent research has shown the potential of non-thermal processing technologies, especially pulsed electric fields (PEF), ultrasounds (US), and high pressure processing (HPP), to trigger the accumulation of bioactive compounds through the induction of a plant stress response. Furthermore, these technologies together with high pressure homogenization (HPH) also cause microstructural changes in both vegetable tissues and plant-based beverages. These modifications could enhance carotenoids, phenolic compounds, vitamins and minerals extractability, and/or bioaccessibility, which is essential to exert their positive effects on health. Nevertheless, information explaining bioaccessibility changes after non-thermal technologies is limited. Therefore, further research on food processing strategies using non-thermal technologies offers prospects to develop plant-based products with enhanced bioaccessibility of their bioactive compounds and micronutrients. In this review, we attempt to provide updated information regarding the main effects of PEF, HPP, HPH, and US on health-related compounds bioaccessibility from different vegetable matrices and the causes underlying these changes. Additionally, we propose future research on the relationship between the bioaccessibility of bioactive compounds and micronutrients, matrix structure, and non-thermal processing.

Physiological and metabolic changes in two Himalayan medicinal herbs under drought, heat and combined stresses.

The online version contains supplementary material available at 10.1007/s12298-021-01027-w.

Growth Quality and Bioactive Compounds of Poplar Seedlings as Affected by Different Fertilization Treatments

Pot experiments were conducted during two successive seasons of 2019 and 2020 at the Fac. of Agric., Minia Univ. to investigate effects of four application rates of compost (0, 1, 2 and 3%) (w/w) and six treatments of bio-fertilizers and/or mineral NPK fertilization (control, Azotobacter chroococcum + Bacillus circulans, Azotobacter chroococcum + Bacillus megaterium, mixture of bio., mixture of bio. + 75% NPK and 100% NPK) on vegetative criteria, accumulation of bioactive compounds (phenolic compounds and flavonoids) through improving plant's secondary metabolism and antimicrobial activity of methanolic and ethanolic extracts of Populus alba. All compost treatments significantly improved all transplant vegetative growth parameters such as plant height, diameter, aerial part fresh and dry weights, main root length and roots fresh and dry weights, as well as, total chlorophylls and NPK% as compared to control. Biofertilizers and/or mineral NPK fertilization treatments significantly increased all the previous traits, the mixture of three species of bacteria plus 75% NPK followed by mineral full dose of NPK treatments were the most effective than other used treatments. The highest values were obtained when Populus alba transplants were grown in sandy soil contained 3% compost plus inoculation with three species of bacteria plus 75% NPK or compost at 3% plus 100 % NPK and these two treatments give the highest values of phenolic compounds in the methanolic and ethanolic extracts. This research confirmed that poplar is a promising wooden tree to be grown on sandy soils for timber production in Egypt, woody products and bioactive compounds.

Post-anthesis thermal stress induces differential accumulation of bioactive compounds in field-grown barley.

Barley (Hordeum vulgare L.) is a healthy grain because of its high content of dietary fibre and phenolic compounds. It faces periods of high temperature during grain filling, frequently reducing grain weight. Heat stress may also affect some of the bioactive compounds present in the grain. To produce quality grains that provide nutritional and health benefits, it is important to understand the effect of environmental stresses on the quantity and quality of bioactive compounds. We have studied the effect of post-anthesis thermal stress on barley bioactive compounds and antioxidant capacity under Mediterranean field conditions during two consecutive growing seasons in four barley genotypes. Thermal stress affected grain weight and size and changed the relative composition of bioactive compounds. The relationship between heat stress and grain β-glucans and arabinoxylans content was indirect, as the resulting increases in concentrations were due to the lower grain weight under stress. Conversely, heat stress had a significant direct impact on some phenolic compounds, increasing their concentrations differentially across genotypes, which contributed to an improvement in antioxidant capacity of up to 30%. Post-anthesis thermal stress had a significant effect on β-glucans, arabinoxylans, phenolic compound concentration and antioxidant capacity of barley grains. Final grain quality could, at least partially, be controlled in order to increase the bioactive concentrations in the barley grain, by cultivation in growing areas prone to heat stress. Late sowings or late flowering genotypes could also be considered, should a premium be implemented to compensate for lower yields. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.