Halophytes of the Mediterranean Basin-Underutilized Species with the Potential to Be Nutritious Crops in the Scenario of the Climate Change

Salinity Influenced Proximate, Minerals, Anti-Nutrients and Phytochemical Composition of Trachyandra ciliata Kunth (Wild Cabbage): A Promising Edible Halophyte

Climate change, drought, and soil salinization present huge limitations to global agricultural output, which threatens food security. This necessitates the cultivation and domestication of wild edible halophytes as alternatives to mainstream food crops, especially in arid and semi-arid regions. Trachyandra ciliata is one of the under-researched and underutilized edible halophytes native to South Africa. The plant was used as a food source by Khoisan people in the past although its edibility and nutritional capacity are undocumented. Thus, the current study explored the effect of varying salinity concentrations on minerals, proximate, phytochemical, and anti-nutrient composition of T. ciliata to evaluate its edibility and promote its cultivation among South African households. Plants were subjected to varying salinity treatments from 0, 50, 100,150, and 200 mM prepared by adding sodium chloride (NaCl) to the nutrient solution. Salinity significantly influenced the mineral, proximate, antinutrient, and phytochemical composition of T. ciliata. Control and 50 mM treatments recorded significantly higher macro and micronutrient content in the flower buds and leaves, except for heavy metals such as Zn and Cu, which increased with increasing salinity and significantly higher in the roots. Leaves under low salinity treatments recorded higher moisture and protein content, while leaves also recorded higher ash content under high salinity. On the other hand, flower buds under low salinity recorded significantly high fat and NDF composition. Phytochemicals and antinutrients increased with increasing salinity concentrations. The low antinutrient content and high nutritional, mineral and phenolic contents validate the edibility and suitability of T. ciliata for human consumption.

Phytochemical Analysis, Acetylcholinesterase Inhibition, Antidiabetic and Antioxidant Activities of Atriplex halimus L. (Amaranthaceae Juss.)

Mediterranean saltbush Atriplex halimus L. (Amaranthaceae) from different bioclimatic arid zones (ten wild populations) were studied. Phenols contents, flavonoids, flavonols, tannins and anthocyanins were determined and then tested for their antioxidants, antidiabetic and anti-acetylcholinesterase (AChE) activities. Levels of total polyphenols including flavonoids and flavonols, tannins and anthocyanins were high and varied significantly among analyzed populations. Nine phenolic acids and four flavonoids were identified for the first time in the methanolic fraction and quantified by liquid high-performance chromatography system HPLC (DAD). All extracts showed a substantial antioxidant activity, as assessed by DPPH assay (1,1-diphenyl-2-picrylhydrazyl free radical) (IC50DPPH=147.3for population of Seliena), Ferric Reducing Antioxidant Power (FRAP; IC50FRAP=3.2 for populations of Sousse and Kairouan), and Chelation Fer test (IC50FerCh=1.5 μg/mL for populations of El-hamma and Mednine). Atriplex halimus possessed a high inhibitory effect against α-amylase activity (up to 2.6 mg ACE/gE), a moderate activity for α-glucosidase (up to 91.0 mg ACE/gE) and AChE (up to 147.2 μg/mL) compared to standard. The analyzed populations were isolated and subdivided into three distinct groups, without any bioclimatic structuration. Enzymatic activities seem to be associated with the presence, in plant extracts, of other classes of compounds then phenols such as terpenes, sterols, saponins, coumarins and carotenoids.

Ecophysiological and nutritional characterisation of two morphotypes of Cakile maritima subsp. maritima Scop. from Puglia region, Southern Italy

Cakile maritima subsp. maritima Scop. (sea rocket) is a succulent halophyte with significant potential as a nutritious food source, being rich in essential nutrients such as vitamins, minerals, and antioxidants. This annual species exhibits two distinct leaf morphotypes: entire lamina (EL) and pinnatifid lamina (PL). Our understanding of their ecophysiological and nutritional profiles is still limited. The present study investigated the wild EL and PL sea rocket plants from southern Italy during their vegetative stage. The bio-morphological traits (leaf mass area-LMA, dry matter and chlorophyll concentrations), main inorganic ions, key antioxidants (carotenoids, anthocyanins, phenols, flavonoids, glucosinolates, vitamin C as ascorbic and dehydroascorbic acid), and antioxidant activity (by FRAP, DPPH, ABTS assays) were analyzed. Additionally, photosynthetic gas exchange and chlorophyll fluorescence were measured. PL plants showed thicker leaves (higher LMA) and greater accumulation of photo-protective pigments (carotenoids and anthocyanins), despite similar chlorophyll levels. The PL plants also demonstrated higher photosynthetic activity, transpiration rates, and stomatal conductance, with reduced non-photochemical quenching. The EL morphotype had higher cation (K, Mg, Ca, Na) and vitamin C (135.3 mg 100 g-1 FW) concentrations, while no significant disparities were observed between the morphotypes in phenolic concentration (208.5 mg g.a.e. 100 g-1 FW), flavonoids (71.5 mg q.e. 100 g-1 FW), or glucosinolates (61 mg g-1 FW). Interestingly, while the EL type had higher vitamin C, the PL morphotype showed superior antioxidant activity (FRAP, DPPH) and seems to be better adapted to water/nutrient scarcity typical of southern Italy. Both morphotypes offer potential as high-nutritional foods, however, future research should investigate the genotype-specific production of antioxidant compounds in EL and PL plants in response to environmental stresses, including salinity for potential exploitation as a new crop.

Correlation of elemental hyperaccumulation among the succulent and non-succulent halophytes of Gujarat, India

This paper presents new data on the salt tolerance and avoidance mechanisms among various groups of halophytes in India. The halophytic flora in general has positive effect of high saline environments on growth and physiology. The coastal area of the Kachchh district in Gujarat includes about 350 km of shoreline along the Gulf of Kachchh. This study presents data on the elemental accumulation mechanisms in soil and halophytic flora (succulent and non-succulents). The halophytes were divided into two groups namely succulent with thick and fleshy leaves and stems as well as non-succulents with thin leaves and stem. The succulent halophytes included species such as Salicornia brachiata, Suaeda fruticosa and Suaeda nudiflora. The non-succulent halophytes include Aeluropus lagopoides and Urochondra setulosa. Plant parts namely leaves (Phylloclade for Salicornia), stems and roots were analyzed during the monsoon season. The results of soil and plant mineral ion contents differed widely across the intertidal zones in the same habitat. Likewise, the intra species have varied in all nutrient levels and salt concentration. The accumulation of elemental concentration was high during the monsoon season in the succulent Salicornia brachiata, especially in leaves that showed Na+ reaching high up to 7.6 meq g-1, whereas Cl- was noted to be 4.34 meq g-1. In the non-succulent halophytes, the accumulation of mineral ion concentration was lower when compared to succulent plants.

Soil physicochemical properties associated with the yield and phytochemical composition of the edible halophyte Crithmum maritimum

There is growing interest in the consumption of halophytes due to their excellent nutritional profile and antioxidant properties, and their cultivation offers viable alternatives in the face of irreversible global salinization of soils. Nevertheless, abiotic factors strongly influence their phytochemical composition, and little is known about how growing conditions can produce plants with the best nutritional and functional properties. Crithmum maritimum is an edible halophyte with antioxidant properties and considerable potential for sustainable agriculture in marginal environments. However, it is found naturally in contrasting habitats with variable soil physicochemical properties and the extent to which edaphic factors can influence plant performance, accumulation of phytochemicals and their quality remains unknown. We investigated the influence of soil physicochemical properties (texture, pH, electrical conductivity, organic matter content and mineral element concentrations) on growth and reproductive performance, nutritional traits, and the accumulation of specific metabolites in C. maritimum. Soil, leaf and seed samples were taken from eight C. maritimum populations located on the southern coasts of Spain and Portugal. We found greater vegetative growth and seed production in coarser, sandier soils with lower microelement concentrations. The nutritional traits of leaves varied, with soil organic matter and macronutrient content associated with reduced leaf Na, protein and phenolic (mainly flavonoid) concentrations, whereas soils with lower pH and Fe concentrations, and higher clay content yielded plants with lower leaf Zn concentration and greater accumulation of hydroxycinnamic acids. The nutritional value of the seed oil composition appeared to be enhanced in soils with coarser texture and lower microelement concentrations. The accumulation of specific phenolic compounds in the seed was influenced by a wide range of soil properties including texture, pH and some microelements. These findings will inform the commercial cultivation of C. maritimum, particularly in the economic exploitation of poorly utilized, saline soils.

Bioactive Extracts from Salicornia ramosissima J. Woods Biorefinery as a Source of Ingredients for High-Value Industries

Salt-tolerant plants, also known as halophytes, could provide a novel source of feedstock for biorefineries. After harvesting fresh shoots for food, the lignified fraction of Salicornia ramosissima J. Woods could be used to produce bioactive botanical extracts for high-value industries such as nutraceuticals, cosmetics, and biopharmaceuticals. The residual fraction after extraction can be further used for bioenergy or lignocellulose-derived platform chemicals. This work analysed S. ramosissima from different sources and growth stages. After pre-processing and extractions, the obtained fractions were analysed for their contents of fatty acids, pigments, and total phenolics. Extracts were also evaluated for their in vitro antioxidant properties and inhibitory effect towards enzymes related to diabetes, hyperpigmentation, obesity, and neurogenerative diseases. The ethanol extract from the fibre residue and the water extract from completely lignified plants showed the highest concentration of phenolic compounds along with the highest antioxidant potential and enzyme-inhibitory properties. Hence, they should be further explored in the context of biorefinery.

Edible Halophytes and Halo-Tolerant Species in Apulia Region (Southeastern Italy): Biogeography, Traditional Food Use and Potential Sustainable Crops

The Mediterranean basin is rich in wild edible species which have been used for food and medicinal purposes by humans throughout the centuries. Many of these species can be found near coastal areas and usually grow under saline conditions, while others can adapt in various harsh conditions including high salinity. Many of these species have a long history of gathering from the wild as a source of food. The aim of this contribution is an overview on the most important halophyte species (Salicornia sp. pl., Arthrocaulon macrostachyum (Moric.) Piirainen & G. Kadereit, Soda inermis Fourr., Cakile maritima Scop., Crithmum maritimum L., Reichardia picroides (L.) Roth., Silene vulgaris (Moench) Garcke subsp. tenoreana (Colla) Soldano & F. Conti, Allium commutatum Guss., Beta vulgaris L. subsp. maritima (L.) Arcang., Capparis spinosa L.) that traditionally have been gathered by rural communities in southern Italy, with special interest on their ecology and distribution, traditional uses, medicinal properties, marketing and early attempts of cultivation. It is worth noting that these species have an attractive new cash crop for marsh marginal lands.

Plant growth, salt removal capacity, and forage nutritive value of the annual euhalophyte Suaeda salsa irrigated with saline water

Sustainable agricultural development in semiarid and arid regions is severely restricted by soil and water salinization. Cultivation of the representative halophyte Suaeda salsa, which can be irrigated with saline water and cultivated on saline soils, is considered to be a potential solution to the issues of freshwater scarcity, soil salinization, and fodder shortage. However, the salt removal capacity and differences in the forage nutritive value of S. salsa under different saline water treatments remain unknown. Using the methods of field trials and randomized blocks design, we quantified salt accumulation in the aboveground biomass, and the biochemical and nutritive value of field-cultivated S. salsa in arid northwestern China under irrigation with water of different salinities [i.e., freshwater or water containing10, 20, 30, or 40 g/L NaCl). The fresh and dry weights of S. salsa increased, then decreased, with increase in salinity. The salt content of the plant's aboveground biomass increased to a constant range and, thus, the salt extraction of S. salsa was relatively stable under different salinities of irrigation water. Under the experimental conditions, the crude protein content significantly increased to 9.45% dry weight (DW) and then decreased to 6.85% DW, with an increase in salinity (p < 0.05). The neutral detergent fiber (42.93%-50.00% DW) and acid detergent fiber (34.76%-39.70% DW) contents were suitable for forage. The contents of trace elements, such as copper and zinc, were significantly increased after irrigation with saline water (p < 0.05). The forage of S. salsa is of high nutritive value for livestock, and contains low concentrations of anti-nutrients. Therefore, S. salsa can be considered for cultivation in saline soils irrigated with saline water. In addition, it provides a viable additional source of fodder in arid regions, where the availability of freshwater and non-saline arable land is limited.

Dietary exposure to heavy metals and iodine intake via consumption of seaweeds and halophytes in the European population

EFSA assessed the relevance of seaweed and halophyte consumption to the dietary exposure to heavy metals (arsenic, cadmium, lead and mercury) and the iodine intake in the European population. Based on sampling years 2011-2021, there were 2,093 analytical data available on cadmium, 1,988 on lead, 1,934 on total arsenic, 920 on inorganic arsenic (iAs), 1,499 on total mercury and 1,002 on iodine. A total of 697 eating occasions on halophytes, seaweeds and seaweed-related products were identified in the EFSA Comprehensive European Food Consumption Database (468 subjects, 19 European countries). From seaweed consumption, exposure estimates for cadmium in adult 'consumers only' are within the range of previous exposure estimates considering the whole diet, while for iAs and lead the exposure estimates represent between 10% and 30% of previous exposures from the whole diet for the adult population. Seaweeds were also identified as important sources of total arsenic that mainly refers, with some exceptions, to organic arsenic. As regards iodine, from seaweed consumption, mean intakes above 20 μg/kg body weight per day were identified among 'consumers only' of Kombu and Laver algae. The impact of a future increase in seaweed consumption ('per capita') on the dietary exposure to heavy metals and on iodine intake will strongly depend on the seaweeds consumed. The exposure estimates of heavy metals and iodine intakes in 'consumers only' of seaweeds were similar to those estimated in a replacement scenario with selected seaweed-based foods in the whole population. These results underline the relevance of the current consumption of seaweeds in the overall exposure to different heavy metals and in the intake of iodine. Recommendations are provided for further work needed on different areas to better understand the relationship between seaweed consumption and exposure to heavy metals and iodine intake.

Biological and Agronomic Traits of the Main Halophytes Widespread in the Mediterranean Region as Potential New Vegetable Crops

Salinity is one of the oldest and most serious environmental problems in the world. The increasingly widespread salinization of soils and water resources represents a growing threat to agriculture around the world. A strategy to cope with this problem is to cultivate salt-tolerant crops and, therefore, it is necessary to identify plant species that are naturally adapted to high-salinity conditions. In this review, we focus our attention on some plant species that can be considered among the most representative halophytes of the Mediterranean region; they can be potential resources, such as new or relatively new vegetable crops, to produce raw or minimally processed (or ready-to-eat) products, considering their nutritional properties and nutraceuticals. The main biological and agronomic characteristics of these species and the potential health risks due to mycotoxigenic fungi have been analyzed and summarized in a dedicated section. The objective of this review is to illustrate the main biological and agronomical characteristics of the most common halophytic species in the Mediterranean area, which could expand the range of leafy vegetables on the market.

Potassium (K+) Starvation-Induced Oxidative Stress Triggers a General Boost of Antioxidant and NADPH-Generating Systems in the Halophyte Cakile maritima

Potassium (K+) is an essential macro-element for plant growth and development given its implication in major processes such as photosynthesis, osmoregulation, protein synthesis, and enzyme function. Using 30-day-old Cakile maritima plants as halophyte model grown under K+ deprivation for 15 days, it was analyzed at the biochemical level to determine the metabolism of reactive oxygen species (ROS), key photorespiratory enzymes, and the main NADPH-generating systems. K+ starvation-induced oxidative stress was noticed by high malondialdehyde (MDA) content associated with an increase of superoxide radical (O2•−) in leaves from K+-deficient plants. K+ shortage led to an overall increase in the activity of hydroxypyruvate reductase (HPR) and glycolate oxidase (GOX), as well as of antioxidant enzymes catalase (CAT), those of the ascorbate-glutathione cycle, peroxidase (POX), and superoxide dismutase (SOD), and the main enzymes involved in the NADPH generation in both leaves and roots. Especially remarkable was the induction of up to seven CuZn-SOD isozymes in leaves due to K+ deficiency. As a whole, data show that the K+ starvation has associated oxidative stress that boosts a biochemical response leading to a general increase of the antioxidant and NADPH-generating systems that allow the survival of the halophyte Cakile maritima.

Extraction and Quantification of Chlorophylls, Carotenoids, Phenolic Compounds, and Vitamins from Halophyte Biomasses

Halophytes are salt-tolerant plants, and they have been utilised as healthy, nutritious vegetables and medicinal herbs. Various studies have shown halophytes to be rich in health-beneficial compounds with antioxidant activity, anti-inflammatory and antimicrobial effects, and cytotoxic properties. Despite their potential, these plants are still underutilised in agriculture and industrial applications. This review includes the state-of-the-art literature concerning the contents of proanthocyanidins (also known as condensed tannins), total phenolic compounds, photosynthetic pigments (chlorophyll and carotenoids), and vitamins in various halophyte biomasses. Various extraction and analytical methods are also considered. The study shows that various species have exhibited potential for use not only as novel food products but also in the production of nutraceuticals and as ingredients for cosmetics and pharmaceuticals.

Comparative Phytochemical Profile and Biological Activity of Four Major Medicinal Halophytes from Qassim Flora

Four halophytic plants, Lycium shawii, Anabasis articulata, Rumex vesicarius, and Zilla spinosa, growing in the central Qassim area, Saudi Arabia, were phytochemically and biologically investigated. Their hydroalcoholic extracts’ UPLC-ESIQ-TOF analyses demonstrated the presence of 44 compounds of phenolic acids, flavonoids, saponins, carbohydrates, and fatty acids chemical classes. Among all the plants’ extracts, L. shawii showed the highest quantities of total phenolics, and flavonoids contents (52.72 and 13.01 mg/gm of the gallic acid and quercetin equivalents, respectively), along with the antioxidant activity in the TAA (total antioxidant activity), FRAP (ferric reducing antioxidant power), and DPPH-SA (2,2-diphenyl-1-picryl-hydrazyl-scavenging activity) assays with 25.6, 56.68, and 19.76 mg/gm, respectively, as Trolox equivalents. The hydroalcoholic extract of the L. shawii also demonstrated the best chelating activity at 21.84 mg/gm EDTA equivalents. Among all the four halophytes, the hydroalcoholic extract of L. shawii exhibited the highest antiproliferative activity against MCF7 and K562 cell lines with IC₅₀ values at 194.5 µg/mL and 464.9 µg/mL, respectively. The hydroalcoholic extract of A. articulata demonstrated better cytotoxic activity amongst all the tested plants’ extracts against the human pancreatic cancer cell lines (PANC1) with an IC₅₀ value of 998.5 µg/mL. The L. shawii induced apoptosis in the MCF7 cell lines, and the percentage of the necrotic cells changed to 28.1% and 36.5% for the IC₅₀ and double-IC₅₀ values at 22.9% compared with the untreated groups. The hydroalcoholic extract of L. shawii showed substantial antibacterial activity against Bacillus cereus ATCC 10876 with a MIC value of 12.5 mg/mL. By contrast, the A. articulata and Z. spinosa exhibited antifungal activities against Aspergillus niger ATCC 6275 with MIC values at 12.5 and 50 mg/mL, respectively. These findings suggested that the L. shawii is a potential halophyte with remarkable biological properties, attributed to its contents of phenolics and flavonoid classes of compounds in its extract.

Nutritional and Functional Evaluation of Inula crithmoides and Mesembryanthemum nodiflorum Grown in Different Salinities for Human Consumption

The nutritional composition and productivity of halophytes is strongly related to the biotic/abiotic stress to which these extremophile salt tolerant plants are subjected during their cultivation cycle. In this study, two commercial halophyte species (Inula crithmoides and Mesembryanthemum nodiflorum) were cultivated at six levels of salinity using a soilless cultivation system. In this way, it was possible to understand the response mechanisms of these halophytes to salt stress. The relative productivity decreased from the salinities of 110 and 200 mmol L⁻¹ upwards for I. crithmoides and M. nodiflorum, respectively. Nonetheless, the nutritional profile for human consumption remained balanced. In general, I. crithmoides vitamin (B1 and B6) contents were significantly higher than those of M. nodiflorum. For both species, β-carotene and lutein were induced by salinity, possibly as a response to oxidative stress. Phenolic compounds were more abundant in plants cultivated at lower salinities, while the antioxidant activity increased as a response to salt stress. Sensory characteristics were evaluated by a panel of culinary chefs showing a preference for plants grown at the salt concentration of 350 mmol L⁻¹. In summary, salinity stress was effective in boosting important nutritional components in these species, and the soilless system promotes the sustainable and safe production of halophyte plants for human consumption.

Influence of soil salinity on the protein and fatty acid composition of the edible halophyte Halimione portulacoides

As the worldwide population continues to rise, so does global demand for agricultural production. This scenario of uncertain food supply is exacerbated by the high salinization of soils worldwide, a serious constraint to crop productivity. In this context, there is an increasing need for alternative sustainable crops. Halophytes are thought to be a promising alternative food source due to their natural ability to grow in saline soils and their multiple potential uses in the food industry. In this study, the protein and fatty acid content of the halophyte Halimione (Atriplex) portulacoides (L.) was studied in different saline conditions. Although more studies are needed to explore the nutritional properties of H. portulacoides, the data presented here suggest that this halophyte should be considered as a promising food crop for saline agriculture.