Phytochemical screening and antimicrobial activities of Periploca aphylla Decne, Persian walnut (Juglans regia L.) and oleander (Nerium indicum Mill.) Leaf extracts

Changes in Carbon Partitioning and Pattern of Antioxidant Enzyme Activity Induced by Arginine Treatment in the Green Microalga Dunaliella salina Under Long-Term Salinity

In this work, the effects of arginine (Arg) on biochemical responses and antioxidant enzyme activity in the green microalga Dunaliella salina grown at different salt concentrations were investigated. Suspensions adapted with the concentrations of 1, 2, and 3 M NaCl were treated at the exponential growth phase with a concentration of 5 mM Arg. Salt stress was associated with a large decrease in the number of cells and non-reducing sugar levels but accumulated higher amounts of chlorophyll, β-carotene, reducing sugar, starch, total protein, free amino acid, and glycerol. Increased levels of protein carbonylation, lipid peroxidation, proteolysis, hydrogen peroxide, and antioxidant enzyme activity also occurred during salinity. Arg treatment changed the pattern of biochemical responses in the cells grown at high salinity by directing carbon flow to the biosynthesis of non-reducing sugars instead of starch, lowering levels of hydrogen peroxide, and downregulating antioxidant enzyme activity, but the levels of lipid peroxidation, glycerol, and β-carotene remained nearly unchanged. These results suggest that Arg treatment alleviates salinity-induced oxidative stress in D. salina cells by modifying carbon partitioning and inducing signaling molecules rather than antioxidant enzymes.

Mineral Composition, Antioxidant, Anti-Urease, and Antibiofilm Potential of Juglans Regia Leaves and Unripe Fruits

The leaves and unripe fruits from 5 walnut clones were tested in terms of mineral composition, antioxidant activity, and the inhibitory effect on model urease. It has been shown that the leaves are richer in minerals and also have higher antioxidant potential than unripe fruits. HPTLC polyphenolic profiles of leaves extract were found more abundant in flavonoids regardless of the sample origin. Only green walnut extracts showed an effect as urease inhibitors. Higher antibacterial activity was observed against Staphylococcus aureus in comparison with Staphylococcus epidermidis. Both leaf and fruit extracts showed antibiofilm activity, up to 95% of biofilm inhibition. It was shown that all tested Juglans regia extracts can serve as a valuable antibacterial agent against staphylococci infections.

Exploration of walnut components and their association with health effects

Traditionally, walnuts have occupied an imperative position in the functional food market with consistently recognized nutritious and functional properties. In the past years, the lipid profile of walnuts has brought much scientific attention via linking a cascade of biological attributes and health-promoting effects. Over time, researchers have focused on diversified composition (polyphenols and vitamins) of different parts of walnut (flower, pellicle, and kernel) and emphasized their physiological significance. Consequently, a plethora of reports has emerged on the potential role of walnut consumption against a series of diseases including cancer, gut dysbiosis, cardiovascular, and neurodegenerative diseases. Therefore, we accumulated the updated data on composition and classification, extraction methods, and utilization of different parts of walnuts as well as associated beneficial effects under in vivo and clinical studies. Altogether, this review summarized the ameliorative effects of a walnut-enriched diet in chronic diseases which can be designated to the synergistic or individual effects of walnut components mainly through anti-oxidative and anti-inflammatory role.

A Comparative Review on the Extraction, Antioxidant Content and Antioxidant Potential of Different Parts of Walnut (Juglans regia L.) Fruit and Tree

As a valuable tree nut, walnut is a well-known member of the Juglandaceae family. The fruit is made up of an outer green shell cover or husk, the middle shell which must be cracked to release the kernel, a thin layer known as skin or the seed coat, and finally, the kernel or meat. The nutritional importance of walnut fruit is ascribed to its kernel. The shell and husk are burned as fuel or discarded away as waste products. In the past two decades, the evaluation of the phenolic content and antioxidant activity of different parts of walnut has received great interest. In this contribution, the recent reports on the extraction and quantification of phenolic content from each part of the walnut tree and fruit using different solvents were highlighted and comparatively reviewed. The current review paper also tries to describe the antioxidant content of phenolic extracts obtained from different parts of the walnut tree and fruit. Additionally, the antioxidant and antiradical activities of the prepared extracts have also been discussed.