Discovering the Potential of Natural Antioxidants in Age-Related Macular Degeneration: A Review

Age-related macular degeneration (AMD) is a multifactorial disease associated with anatomical changes in the inner retina. Despite tremendous advances in clinical care, there is currently no cure for AMD. This review aims to evaluate the published literature on the therapeutic roles of natural antioxidants in AMD. A literature search of PubMed, Web of Science and Google Scholar for peer-reviewed articles published between 1 January 2011 and 31 October 2021 was undertaken. A total of 82 preclinical and 18 clinical studies were eligible for inclusion in this review. We identified active compounds, carotenoids, extracts and polysaccharides, flavonoids, formulations, vitamins and whole foods with potential therapeutic roles in AMD. We evaluated the integral cellular signaling pathways including the activation of antioxidant pathways and angiogenesis pathways orchestrating their mode of action. In conclusion, we examined the therapeutic roles of natural antioxidants in AMD which warrant further study for application in clinical practice. Our current understanding is that natural antioxidants have the potential to improve or halt the progression of AMD, and tailoring therapeutics to the specific disease stages may be the key to preventing irreversible vision loss.

Biocompatibility and Antioxidant Capabilities of Carbon Dots Obtained from Tomato (Solanum lycopersicum)

Since their discovery in 2004, carbon dots have attracted strong interest in the scientific community due to their characteristic properties, particularly their luminescence and their ease of synthesis and derivatization. Carbon dots can be obtained from different carbon sources, including natural products, resulting in a so-called ’green synthesis’. In this work, we obtain carbon dots from tomato juice in order to obtain nanoparticles with the antioxidant capabilities of the natural antioxidants present in that fruit. The obtained material is characterized regarding nanoparticle size distribution, morphology, surface functional groups and optic properties. Antioxidant properties are also evaluated through the DPPH method and their cytotoxicity is checked against human dermal fibroblast and A549 cell-lines. The results indicate that carbon dots obtained from tomato have a higher antioxidant power than other already-published antioxidant carbon dots. The bandgap of the synthesized materials was also estimated and coherent with the literature values. Moreover, carbon dots obtained from tomato juice are barely toxic for healthy cells up to 72 h, while they induce a certain cytotoxicity in A549 lung carcinoma cells.

Natural Variation of Seed Tocopherol Composition in Diverse World Soybean Accessions from Maturity Group 0 to VI Grown in China

Tocopherols are natural antioxidants that increase the stability of fat-containing foods and are well known for their health benefits. To investigate the variation in seed tocopherol composition of soybeans from different origins, 493 soybean accessions from different countries (China, USA, Japan, and Russia) belonging to 7 maturity groups (MG 0–VI) were grown in 2 locations (Beijing and Hainan Provinces of China) for 2 years (2017 and 2018). The results showed that significant differences (p < 0.001) were observed among the accessions and origins for individual and total tocopherol contents. The total tocopherol content ranged from 118.92 μg g−1 to 344.02 μg g−1. Accessions from the USA had the highest average concentration of γ- and total tocopherols (152.92 and 238.21 μg g−1, respectively), whereas a higher level of α-tocopherol (12.82 μg g−1) was observed in the Russian accessions. The maturity group of the accession significantly (p < 0.001) influenced all tocopherol components, and higher levels of α-, γ-, and total tocopherols were observed in early maturing accessions, while late-maturing accessions exhibited higher levels of δ-tocopherol. The inclination of tocopherol concentrations with various MGs provided further evidence of the significance of MG in soybean breeding for seed tocopherol components. Furthermore, the correlation between the seed tocopherol components and geographical factors revealed that α-, γ-, and total tocopherols had significant positive correlations with latitude, while δ-tocopherol showed an opposite trend. The elite accessions with high and stable tocopherol concentrations determined could be used to develop functional foods, industrial materials, and breeding lines to improve tocopherol composition in soybean seeds.

Innovative and Sustainable Technologies to Enhance the Oxidative Stability of Vegetable Oils

To meet consumers’ demand for natural foods, edible oil producers and food processing industries are searching for alternatives to synthetic antioxidants to protect oils against oxidation. Antioxidant compounds extracted from different plant parts (e.g., flowers, leaves, roots, and seeds) or sourced from agri-food industries, including residues left after food processing, attract consumers for their health properties and natural origins. This review, starting from a literature research analysis, highlights the role of natural antioxidants in the protection of edible oils against oxidation, with an emphasis on the emerging and sustainable strategies to preserve oils against oxidative damage. Sustainability and health are the main concerns of food processing industries. In this context, the aim of this review is to highlight the emerging strategies for the enrichment of edible oils with biomolecules or extracts recovered from plant sources. The use of extracts obtained from vegetable wastes and by-products and the blending with oils extracted from various oil-bearing seeds is also pointed out as a sustainable approach. The safety concerns linked to the use of natural antioxidants for human health are also discussed. This review, using a multidisciplinary approach, provides an updated overview of the chemical, technological, sustainability, and safety aspects linked to oil protection.

Extraction, Purification and In Vitro Antioxidant Activity Evaluation of Phenolic Compounds in California Olive Pomace

Olive pomace (OP) is a valuable food byproduct that contains natural phenolic compounds with health benefits related to their antioxidant activities. Few investigations have been conducted on OP from the United States while many studies on European OP have been reported. OP of Arbequina, the most common cultivar from California, was collected and extracted by water, 70% methanol and 70% ethanol, followed by purification using macroporous absorbing resin. Results showed that the extractable total phenolic content (TPC) was 36–43 mg gallic acid equivalents (GAE)/g in pitted, drum-dried defatted olive pomace (DOP), with major contributions from hydroxytyrosol, oleuropein, rutin, verbascoside, 4-hydroxyphenyl acetic acid, hydroxytyrosol-glucoside and tyrosol-glucoside. Macroporous resin purification increased TPC by 4.6 times the ethanol crude extracts of DOP, while removing 37.33% total sugar. The antioxidant activities increased 3.7 times Trolox equivalents (TrE) by DPPH and 4.7 times TrE by ferric reducing antioxidant power (FRAP) in the resin purified extracts compared to the ethanol crude extracts. This study provided a new understanding of the extraction of the bioactive compounds from OP which could lead to practical applications as natural antioxidants, preservatives and antimicrobials in clean-label foods in the US.

Effect of the Addition of Thyme “Thymus vulgaris” Leaves on the Sensory and Nutritional Quality of Lamb Meat

Background: The shelf life of meat products can be increased by adding synthetic antioxidants. These antioxidants have long been used, but their safety has recently come into dispute due to a suspected carcinogenic potential. This is why meat technologies have extracted new natural antioxidants from spices and herbs, which are the best alternatives to synthetic compounds. So, the addition of natural flavors (essential oils, powder or extract of aromatic plants) to the meat can improve organoleptic quality and consumer acceptability. Methods: This study was conducted to evaluate the physicochemical and organoleptic qualities of meat fortified with thyme powder. With this purpose, 16 samples from four muscles of legs from 4 lambs were used in this work. The muscles were divided into two groups, control group (meat without any supplementation) and thyme group (meat supplemented with thyme). In this later group, a dose of 5% of ground thyme dry leaves was added to the meat. Result: Results showed no significant differences were found among groups for cooking loss, but was slightly higher for meat treated with thymus (33.29 vs. 28.36%). No significant differences between the two groups were observed for the ash, fat and crude protein contents of the meat. At the same manner, no effect was observed on meat lightness (L) and yellowness (b*) (P greater than 0.05), on the contrary, redness (a*) of the meat was affected by addition of thyme (11.28±1.23 vs. 23.06±9.80). Also, significant (P less than 0.05) differences were observed in texture scores, flavor, color and taste between control and the 5% thyme-supplemented meat samples. The overall acceptability of supplemented meat samples was highest (P≤0.05) as compared to control (5.91±2.32 vs. 4.35±2.66). In conclusion, addition of thyme leaves did not affect the physical and chemical properties of meat, except for redness and improved sensory quality.

Plant-Derived Antioxidants: Significance in Skin Health and the Ageing Process

Natural substances have traditionally been used in skin care for centuries. There is now an ongoing search for new natural bioactives that not only promote skin health but also protect the skin against various harmful factors, including ultraviolet radiation and free radicals. Free radicals, by disrupting defence and restoration mechanisms, significantly contribute to skin damage and accelerate ageing. Natural compounds present in plants exhibit antioxidant properties and the ability to scavenge free radicals. The increased interest in plant chemistry is linked to the growing interest in plant materials as natural antioxidants. This review focuses on aromatic and medicinal plants as a source of antioxidant substances, such as polyphenols, tocopherols, carotenoids, ascorbic acid, and macromolecules (including polysaccharides and peptides) as well as components of essential oils, and their role in skin health and the ageing process.

Antioxidant and Free Radical Scavenging Activity Comparison in Various Plant Parts of Justicia adhatoda L.

There are many medicinal plants that have various medicinal properties in their different parts. The medicinal plants are major backbone of pharmaceutical industries. In this article we compare the antioxidants properties from various plants parts (root, stem, leaf, flower and bark) of the most important medicinal plant, Justicia adhatoda L. Various plant parts showed the good amount of antioxidant properties. These results enhance the medicinal properties of this plant due to the presence of good amount of antioxidants; among all the plant parts leaves and flowers showed maximum natural antioxidants, hence the study could be saying that this plant has good efficacy of antioxidants.

Medicinal Importance of Ajuga Species in Iran: Ethnobotanical and Traditional Applications, Phytochemical, and Pharmacological Studies

Context: Five species of the genus Ajuga (Lamiaceae) having the common name of "bugle" are found in Iran. In Persian medicine (PM), the genus Ajuga (Kamaphytus) is used for treating jaundice, joint pain, gout, amenorrhea, sciatica, and wound healing. This study aimed to review the ethnobotanical, phytochemical, and biological activities of Ajuga species that grow in Iran to determine their therapeutic potentials and suggest further studies on the healing properties of this genus in Iran. Evidence Acquisition: Electronic databases such as PubMed, Scopus, and Google Scholar were comprehensively searched for studies on Ajuga species in Iran, including "Ajuga austro-iranica," "Ajuga chamaecistus," "Ajuga comata" (Syn.: "Ajuga Chia," "Ajuga chamaepitys subsp. Chia"), "Ajuga orientalis," and "Ajuga reptans." The search period was from 1966 to February 2021. The related articles were selected according to the inclusion and exclusion criteria of the current study. Results: Several ethnobotanical and pharmacologic reports have verified the traditional uses of the genus Ajuga for anti-inflammatory, hypoglycemic, hypolipidemic, analgesic, anabolic, anti-arthritis, antipyretic, and hepatoprotective activities. Numerous phytochemicals have been identified from Ajuga species involving phytoecdysteroids, neo-clerodane-diterpenes, iridoids, flavonoids, withanolides, phenylethyl glycoside, and essential oils. Conclusions: Due to the beneficial therapeutic effects of Ajuga genus, it can be considered in future clinical studies as a source of natural antioxidants, dietary supplements in the pharmaceutical industry, and stabilizing food against oxidative deterioration.