Progress in the Study and Use of Seawater Vegetables

Identification of Polyphenols in Sea Fennel (Crithmum maritimum) and Seaside Arrowgrass (Triglochin maritima) Extracts with Antioxidant, ACE-I, DPP-IV and PEP-Inhibitory Capacity

Sea fennel and seaside arrowgrass are two abundant but underutilized halophytes along the Atlantic and Mediterranean coasts. This study investigated the antioxidant capacity and the potential antihypertensive (Angiotensin Converting Enzyme I, ACE-I inhibition), hypoglycaemic (Dipeptidyl Peptidase IV, DPP-IV inhibition), and nootropic (Prolyl Endopeptidase, PEP inhibition) activity of their polyphenol extracts. They had a high phenol content (21-24 mEq GA/g), antioxidant capacity evaluated using the ABTS (17-2 mg ascorbic acid/g) and FRAP (170-270 mM Mohr's salt/g) assays, and effective ACE-inhibiting properties (80-90% inhibiting activity at final concentration of 0.5 mg/mL). Additionally, the sea fennel extract displayed high DPP-IV inhibitory capacity (73% at 1 mg/mL), while the seaside arrowgrass extract exhibited potent Prolyl endopeptidase inhibitory capacity (75% at 1 mg/mL). Fractionation by HPLC concentrated the bioactive molecules in two fractions, for which the composition was analyzed by LC-MS/MS. Different chlorogenic acids seemed to play an important role in the bioactivity of sea fennel extract, and different flavonoids, mainly apigenin, luteolin and chrysoeriol, in the bioactivity of the seaside arrowgrass extract. Given their potential health benefits, these extracts could serve as valuable bioactive ingredients and could potentially encourage the cultivation of these species in regions where traditional crops face challenges in growth.

Economic Uses of Salt-Tolerant Plants

Climate change is likely to affect the ability of world agricultural systems to provide food, fibre, and fuel for the growing world population, especially since the area of salinised land will increase. However, as few species of plants (less than 1% of all plant species) can tolerate saline soils, we believe it is important to evaluate their potential as crops for salinised soils. We have analysed the economic and potential economic uses of plants that are listed in the database eHALOPH, including the most tolerant species, halophytes. For nine main categories of economic value, we found a total of 1365 uses amongst all species listed in eHALOPH as of July 2022; this number reduced to 918 amongst halophytes. We did not find any obvious differences in rankings between the more tolerant halophytes and the whole group of salt-tolerant plants, where the order of use was medical, followed by forage, traditional medicine, food and drink, fuel, fuelwood, and bioenergy. While many species are potentially important as crops, the effects of salt concentration on their uses are much less well documented. Increasing salt concentration can increase, decrease, or have no effect on the concentration of antioxidants found in different species, but there is little evidence on the effect of salinity on potential yield (the product of concentration and biomass). The effect of salinity on forage quality again varies with species, often being reduced, but the overall consequences for livestock production have rarely been evaluated. Salt-tolerant plants have potential uses in the bioremediation of degraded land (including revegetation, phytoremediation, and extraction of NaCl) as well as sources of biofuels, although any use of saline water for the sustainable irrigation of salt-tolerant crops must be viewed with extreme caution.

Halophytes as Medicinal Plants against Human Infectious Diseases

Halophytes have long been used for medicinal purposes. However, for many decades, their use was entirely empirical, with virtually no knowledge of the bioactive compounds underlying the different applications. In recent decades, the growing problem of antibiotic resistance triggered the research on alternative antimicrobial approaches, and halophytes, along with other medicinal plants, regained attention as an underexplored pharmacological vein. Furthermore, the high nutritional/nutraceutical/pharmacological value of some halophytic species may represent added value to the emerging activity of saline agriculture and targeted modification of the rhizosphere, with plant-growth-promoting bacteria being attempted to be used as a tool to modulate the plant metabolome and enhance the expression of interesting metabolites. The objective of this review is to highlight the potential of halophytes as a valuable, and still unexplored, source of antimicrobial compounds for clinical applications. For that, we provide a critical perspective on the empirical use of halophytes in traditional medicine and a state-or-the-art overview of the most relevant plant species and metabolites related with antiviral, antifungal and antibacterial activities.

Protection of Halophytes and Their Uses for Cultivation of Saline-Alkali Soil in China

Over 800 million hectares of arable lands are affected by salinity in the world. In China, saline-alkali soils account for 25% of farmland and are underutilized. One sustainable strategy to make better use of saline land is to plant halophytes, salt-tolerant plants that can survive and complete their life cycle in media containing more than 200 mM NaCl. Halophytes have potential economic value as grain, vegetable, fruit, medicine, animal feed, and biofuel feedstocks, and in greening and coastal protection. Therefore, the cultivation and protection of halophytes is very important. In the past few decades, a lot of work has been done on the protection and utilization of halophytes in saline soil improvement and development worldwide. This article focuses on the distribution of saline-alkali conditions and current measures to protect halophytes, as well as the application of halophytes in the sustainable development of saline-alkali land. This information is helpful for protection and utilization of halophytes in the sustainable development of saline land worldwide.