Walnut oil, like all vegetable oils, is chemically unstable because of the sensitivity of its unsaturated fatty acids to the oxidation phenomenon. This phenomenon is based on a succession of chemical reactions, under the influence of temperature or storage conditions, that always lead to a considerable change in the quality of the oil by promoting the oxidation of unsaturated fatty acids through the degradation of their C–C double bonds, leading to the formation of secondary oxidation products that reduce the nutritional values of the oil. This research examines the oxidative stability of roasted and unroasted cold-pressed walnut oils under accelerated storage conditions. The oxidative stability of both oils was evaluated using physicochemical parameters: chemical composition (fatty acids, phytosterols, and tocopherols), pigment content (chlorophyll and carotenoids), specific extinction coefficients (K₂₃₂ and K₂₇₀), and quality indicators (acid and peroxide value) as well as the evaluation of radical scavenging activity by the DPPH method. The changes in these parameters were evaluated within 60 days at 60 ± 2 °C. The results showed that the levels of total phytosterols, the parameters of the acid and peroxide value, K₂₃₂ and K₂₇₀, increased slightly for both oils as well as the total tocopherol content and the antioxidant activity affected by the roasting process. In contrast, the fatty acid profiles did not change considerably during the 60 days of our study. After two months of oil treatment at 60 °C, the studied oils still showed an excellent physicochemical profile, which allows us to conclude that these oils are stable and can withstand such conditions. This may be due to the considerable content of tocopherols (vitamin E), which acts as an antioxidant.

The present study investigated and compared the quality and chemical composition of Moroccan walnut (Juglans regia L.) oil. This study used three extraction techniques: cold pressing (CP), soxhlet extraction (SE), and ultrasonic extraction (UE). The findings showed that soxhlet extraction gave a significantly higher oil yield compared to the other techniques used in this work (65.10% with p < 0.05), while cold pressing and ultrasonic extraction gave similar yields: 54.51% and 56.66%, respectively (p > 0.05). Chemical composition analysis was carried out by GC–MS and allowed 11 compounds to be identified, of which the major compound was linoleic acid (C18:2), with a similar percentage (between 57.08% and 57.84%) for the three extractions (p > 0.05). Regarding the carotenoid pigment, the extraction technique significantly affected its content (p < 0.05) with values between 10.11 mg/kg and 14.83 mg/kg. The chlorophyll pigment presented a similar content in both oils extracted by SE and UE (p > 0.05), 0.20 mg/kg and 0.16 mg/kg, respectively, while the lowest content was recorded in the cold-pressed oil with 0.13 mg/kg. Moreover, the analysis of phytosterols in walnut oil revealed significantly different contents (p < 0.05) for the three extraction techniques (between 1168.55 mg/kg and 1306.03 mg/kg). In addition, the analyses of tocopherol composition revealed that γ-tocopherol represented the main tocopherol isomer in all studied oils and the CP technique provided the highest content of total tocopherol with 857.65 mg/kg, followed by SE and UE with contents of 454.97 mg/kg and 146.31 mg/kg, respectively, which were significantly different (p < 0.05). This study presents essential information for producers of nutritional oils and, in particular, walnut oil; this information helps to select the appropriate method to produce walnut oil with the targeted quality properties and chemical compositions for the desired purpose. It also helps to form a scientific basis for further research on this plant in order to provide a vision for the possibility of exploiting these oils in the pharmaceutical, cosmetic, and food fields.

The increasing demand for plant-based medicines makes plant research attractive to find natural alternatives that can replace synthetic products or at least reduce their use. Saponins are a group of natural phytochemical compounds in most herbs, vegetables, and legumes. There are two different types of saponin compounds, which can be classified based on the nature of the aglycone bound to the oligosaccharide fragments, whether it is a steroid or triterpenoid. This paper is devoted to saponins with triterpenoid aglycone and aims to study the relationship between their content and several biological activities in different Juglans regia kernel extracts, including antioxidant, antimicrobial and antibacterial activities. Antioxidant activity was assessed against two free radicals: DPPH and ABTS. Oleanolic acid was used as a standard to quantify triterpenoid saponins, measured by the vanillin method, whereas Acarbose and Tetracycline were used as positive controls to evaluate the α-glucosidase inhibitory and antimicrobial activities, respectively, of walnut kernel extracts. Findings show that hydroalcoholic extract (EtOH 70%) has a considerable content of phenolic compounds, with 59.51 ± 0.26 mg GAE/g in total polyphenol contents, while the content of total flavonoids and condensed tannins were 3.14 ± 0.27 mg QE/g and 85.65 ± 0.37 mg CE/g of crude extract, respectively. In terms of antioxidant activity, the butanolic extract proved to be the most effective against DPPH with IC50 = 7.74 ± 1.49 µg/mL, while the precipitated extract showed the highest scavenging activity against the ABTS free radical with IC50 = 33.14 ± 2.96 µg/mL. In addition, butanolic and hydroalcoholic extracts of Juglans regia kernels showed an α-glucosidase inhibitory activity even more efficiently than synthetic drugs such as Acarbose, with IC50 values of 11.66 µg/mL and 16.17 µg/mL, respectively, versus 18.01 µg/mL in Acarbose. The evaluation of the antimicrobial activity against Bacillus subtilis, Escherichia coli and Klebsiella pneumonia strains revealed that some extracts could inhibit these bacteria. This study successfully assessed the bioactivities of the extracts, suggesting that the extracts of medicinal plants can demonstrate stronger bioactivity than pure synthetic compounds.

This study examines the effect of UV irradiation on the oxidation stability of Linum usitatissimum oil, presenting possible changes in the phytochemical profile due to photo-oxidation. GC-MS analysis of the oils identified 11 fatty acid compounds with a high percentage of unsaturated fatty acids, the most important of which is α-linolenic acid (ALA), known as omega-3 (48.88 %), also significant profiles of phytosterol and tcocopherol isomers rich in β-Sitosterol and γ-tocopherols respectively. As well as physicochemical properties such as free fatty acids (FFA %), peroxide value (PV) and iodine value (IV), and nutritional indexes that determine the significant changes observed during the oxidation process, the most important of which is the progressive increase in acidity, peroxide, conjugated dienes and trienes and degrees of unsaturation over 8 h of UV exposure. High levels of carotenoids and phenolic compounds (TPC) protect and enhance oil quality in the face of irradiation, so a significantly small difference is observed between irradiated and non-irradiated oil during photo-oxidation.

Retama monosperma L. (Boiss.) or Genista monosperma L. (Lam.), known locally as “R’tam”, is a spontaneous and annual herb that belongs to the Fabaceae family. It is native to the Mediterranean regions, specifically in the desert areas and across the Middle Atlas in Morocco. This plant has been extensively used in folk medicine and it is rich in bioactive compounds, including polyphenols, flavonoids, and alkaloids. Current research efforts are focusing on the development of novel natural drugs as alternatives to various organic and non-organic chemical products from Retama monosperma. In addition, extract, and isolated compounds obtained from different parts of the chosen plant have been described to exhibit multiple biological and pharmacological properties such as antioxidant, anti-aging, anti-inflammatory, antihypertensive, anti-helminthic, disinfectant, diuretic, and hypoglycemic effects. The plant-derived extract also acts as an antimicrobial agent, which is highly efficient in the treatment of bacterial, viral, and fungal infections. Its antiproliferative effects are associated with some mechanisms, such as the inhibition of cell cycle arrest and apoptosis. In light of these assessments, we critically highlight the beneficial effects of the flowers, stems, seeds extracts, and isolated compounds from R. monosperma (L.) Boiss in human health care, industrial, and other applications, as well as the possible ways to be employed as a potential natural source for future drug discovery.

The argan tree is a versatile forest tree (silviculture-fruit-forestry) of great importance for the country both in biological, phytogenetic and ecological biodiversity as well as in economic and social aspects. It has significant medicinal and therapeutic potential. The present study concentrated on saccharide-containing molecules, particularly saponins, for their medicinal properties. Butanol was used to fractionate phytochemical groups from different parts of Argania spinosa (branch, leaf, pulp, shell and seed), which were subsequently precipitated in ether. It was found that solvent fractionation increased the total saponin amount according to the colorimetric test using vanillin and sulfuric acid. The butanol fraction of the argan shell and its precipitate showed the highest levels of triterpene saponins compared to the rest of the plant parts studied. The samples showed antioxidant capacity by DPPH versus ascorbic acid (IC50 = 1.92 µg/mL) and by ABTS using the similar standard (IC50 = 11.31 µg/mL). The antioxidant activity of the samples was significantly improved from the crude shell extract (IC50 = 5.85 µg/mL) to its butanolic fraction (IC50 = 2.94 µg/mL) and its precipitate (IC50 = 1.57 µg/mL) using 2,2-diphenyl-picrylhydrazyl. Indeed, the ABTS test, showed similarity to the core results. Also, the solid disc diffusion method was used to highlight the antimicrobial activity of extracts from different parts of the Argania spinosa plant. The EtOH 70% and Aqueous leaf extracts exhibited the highest antibacterial activity, resulting in an inhibition zone of approximately 13 mm against the growth of Staphylococcus saprophyticus. On the other hand, the extract of saponin filtrate from the pulp part of the plant displayed the lowest antibacterial activity, with an inhibition zone of 9 mm. All studied types of saponin extract from different parts of the plant do not contribute to any antifungal activity against Botrytis cinerea.