By-Products of Walnut (Juglans regia) as a Source of Bioactive Compounds for the Formulation of Nutraceuticals and Functional Foods

Abstract

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Chemical Profiling, Bioactive Properties, and Anticancer and Antimicrobial Potential of Juglans regia L. Leaves

“…Walnut ( Juglans regia L.) belongs to the Juglandaceae family. The leaders in the global production of walnuts are China, the United States, and Europe, but they are appreciated all over the world for their nutritional and sensory properties, as well as health benefits [ 2 ]. Walnuts are a rich source of polyphenols, the concentration of which depends on the date of harvest, variety [ 3 , 4 , 5 ], maturity level [ 6 ], geographical location [ 7 ], climatic and agrotechnical conditions.…”

“…The edible parts of Juglans regia L. are kernels, containing in their composition polyunsaturated fatty acids (PUFA), vitamins, tocopherols, phytosterols, and several other bioactive substances important in the prevention of non-infectious diet-related diseases [ 3 , 4 , 5 ]. In addition, other parts of Juglans regia L., such as leaves, green shell (exocarp), woody shell (endocarp), flowers, pollen, and bark, are valuable products as well [ 2 ]. Walnut leaf infusion is used in traditional medicine in the treatment of venous insufficiency, as well as hemorrhoids, due to its antifungal, antibacterial, anthelmintic, astringent, and hypoglycemia properties [ 8 ].…”

“…Nour et al (2013) indicate that these properties are related to the high content of tannins, phenolic acids, and flavonoids [ 9 ]. The global production of walnuts has also contributed to the formation of a huge amount of by-products that are incinerated, composted, or landfilled [ 2 ]. In turn, the woody shells serve as a source of energy for heating, an abrasive agents for cleaning and polishing metals, plastics, as a filter medium for separating oil, hazardous materials, and heavy metals [ 2 , 10 ].…”

“…The global production of walnuts has also contributed to the formation of a huge amount of by-products that are incinerated, composted, or landfilled [ 2 ]. In turn, the woody shells serve as a source of energy for heating, an abrasive agents for cleaning and polishing metals, plastics, as a filter medium for separating oil, hazardous materials, and heavy metals [ 2 , 10 ]. Żurek et al (2022 a,b) showed that both flowers and pollen from a walnut growing in the Subcarpathian region (Poland) have strong antioxidant, anti-microbial, and anti-carcinogenic potential and, thus, can be used as nutraceuticals or for food enrichment [ 11 , 12 ].…”

Review on Tannic Acid: Potensial Sources, Isolation Methods, Aplication and Bibliometric Analysis

“…Furthermore, walnut husk and shells also reported as source of tannic acid. It was mentioned that 120.4 ± 4.19 mg GAEs/L extract is obtained from walnut shell extraction [17]. Quercus genus which is belongs to the Fagaceae family and comprises of many species is also stated as rich sources of tannic acid.…”