Sarah Al-Rashed

Bio: Sarah Al-Rashed is an academic researcher from King Saud University. The author has contributed to research in topics: Photocatalysis & Nanocomposite. The author has an hindex of 9, co-authored 41 publications receiving 221 citations.

Antioxidant, Anticancer Activity and Phytochemical Analysis of Green Algae, Chaetomorpha Collected from the Arabian Gulf.

Abstract: Seaweeds are a group of marine multicellular algae; the presence of antioxidant phytochemical constituents in Seaweed Chaetomorpha sp. extracts has received attention for their role in the prevention of human diseases. This study explores the phytochemical constituents, antioxidant, and anticancer properties of the Cladophoraceae, Chaetomorpha sp. Energy dispersive x-ray spectroscopy (EDX), and Gas chromatography-mass spectrometry (GC/MS) were performed to study the chemical structure and chemical formula. Different concentrations of ethanol and aqueous extracts of Chaetomorpha were used to estimate antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and total flavonoid, phenolic, and tannins content assays. Anti-tumor activity against breast cancer cell lines (MCF-7 and MDA-MB-231) was assessed by 3-(4,5-Dimethylthiazol-2-cyl)-2,5-Diphenyltetrazolium Bromide (MTT) assay. The EDX analysis indicated the presence of oxygen, silicon, and calcium as dominant elements. Antioxidant assays indicated that the ethanol extracts of Chaetomorpha consisted of a total of 189.14 ± 0.99 mg QE/g flavonoid content, 21.92 ± 0.43 mg GAE/g phenolic content and 21.81 ± 0.04 mg GAE/g tannins content. The DPPH radical scavenging assay exhibited higher antioxidant activity IC50 (9.41 ± 0.54 mg/mL) in the ethanol extract. Moreover, it showed high anticancer activity by growth inhibition in the MDA-MB-231 breast cancer cell line and low IC50 (225.18 ± 0.61 µg/mL). GC/MS analysis revealed the presence of Dichloracetic acid (DCA) as the active antitumor constituent of Chaetomorpha sp.; other anticancer compounds identified were Oximes and L-α-Terpinol. The results revealed that the type of Chaetomorpha sp. studied here possesses very unique and novel constituents and active potent antitumor chemical constituents and it can act as a promising antioxidant and anticancer agent for future applications in pharmaceutical industries.

Antioxidant System and Biomolecules Alteration in Pisum sativum under Heavy Metal Stress and Possible Alleviation by 5-Aminolevulinic Acid.

Abstract: Environmental pollution is the most serious problem that affects crop productivity worldwide. Pisum sativum is a leguminous plant that is cultivated on a large scale in the Nile Delta of Egypt as a winter crop, and many of the cultivated fields irrigated with drainage water that contained many pollutants including heavy metals. The present research aimed to investigate the impact of Cd and Ni on the biochemical and physiological processes in P. sativum and evaluate the potential alleviation of their toxicity by 5-aminolevulinic acid (ALA). Seedlings of P. sativum were grown in Hoagland solution treated with CdCl2 or NiCl2 for 72 h in the growth chamber. Hydrogen peroxide, lipid peroxidation, protein carbonylation, reduced glutathione, oxidized glutathione, proline, phenolics, antioxidant enzymes, as well as Cd and Ni concentrations were measured at 0, 12, 24, 36, 48, 72 h. An experiment of alleviation was conducted where ALA was added to the growth solution at a concentration of 200 µM coupled with 100 µM of either CdCl2 or NiCl2. Hydrogen peroxide, lipid peroxidation, protein carbonylation, reduced glutathione, oxidized glutathione, proline, and phenolics were induced due to the toxicity of Cd and Ni. The activities of antioxidant enzymes [NADH-oxidase (EC: 1.6.3.1), ascorbate peroxidase (EC: 1.11.1.11), glutathione reductase (EC: 1.6.4.2), superoxide dismutase (EC: 1.15.1.1), and catalase (EC: 1.11.1.6)] were induced under the treatments of both metals. On the other hand, the soluble protein decreased gradually depending upon the time of exposure to the heavy metals. The concentration of Cd and Ni in the leaves treated plants increased in time of exposure dependent manner, while their contents remained within the acceptable limits. The addition of ALA decreased the oxidative stress in treated P. sativum plants. The results revealed the significance of using ALA in the cultivation of P. sativum might improve its tolerance against heavy metal stress.

Reactive Oxygen Species and Antioxidant Defense in Plants under Abiotic Stress: Revisiting the Crucial Role of a Universal Defense Regulator

Abstract: Global climate change and associated adverse abiotic stress conditions, such as drought, salinity, heavy metals, waterlogging, extreme temperatures, oxygen deprivation, etc., greatly influence plant growth and development, ultimately affecting crop yield and quality, as well as agricultural sustainability in general. Plant cells produce oxygen radicals and their derivatives, so-called reactive oxygen species (ROS), during various processes associated with abiotic stress. Moreover, the generation of ROS is a fundamental process in higher plants and employs to transmit cellular signaling information in response to the changing environmental conditions. One of the most crucial consequences of abiotic stress is the disturbance of the equilibrium between the generation of ROS and antioxidant defense systems triggering the excessive accumulation of ROS and inducing oxidative stress in plants. Notably, the equilibrium between the detoxification and generation of ROS is maintained by both enzymatic and nonenzymatic antioxidant defense systems under harsh environmental stresses. Although this field of research has attracted massive interest, it largely remains unexplored, and our understanding of ROS signaling remains poorly understood. In this review, we have documented the recent advancement illustrating the harmful effects of ROS, antioxidant defense system involved in ROS detoxification under different abiotic stresses, and molecular cross-talk with other important signal molecules such as reactive nitrogen, sulfur, and carbonyl species. In addition, state-of-the-art molecular approaches of ROS-mediated improvement in plant antioxidant defense during the acclimation process against abiotic stresses have also been discussed.

Arsenic uptake, toxicity, detoxification, and speciation in plants : physiological, biochemical, and molecular aspects

Abstract: Environmental contamination with arsenic (As) is a global environmental, agricultural and health issue due to the highly toxic and carcinogenic nature of As. Exposure of plants to As, even at very low concentration, can cause many morphological, physiological, and biochemical changes. The recent research on As in the soil-plant system indicates that As toxicity to plants varies with its speciation in plants (e.g., arsenite, As(III); arsenate, As(V)), with the type of plant species, and with other soil factors controlling As accumulation in plants. Various plant species have different mechanisms of As(III) or As(V) uptake, toxicity, and detoxification. This review briefly describes the sources and global extent of As contamination and As speciation in soil. We discuss different mechanisms responsible for As(III) and As(V) uptake, toxicity, and detoxification in plants, at physiological, biochemical, and molecular levels. This review highlights the importance of the As-induced generation of reactive oxygen species (ROS), as well as their damaging impacts on plants at biochemical, genetic, and molecular levels. The role of different enzymatic (superoxide dismutase, catalase, glutathione reductase, and ascorbate peroxidase) and non-enzymatic (salicylic acid, proline, phytochelatins, glutathione, nitric oxide, and phosphorous) substances under As(III/V) stress have been delineated via conceptual models showing As translocation and toxicity pathways in plant species. Significantly, this review addresses the current, albeit partially understood, emerging aspects on (i) As-induced physiological, biochemical, and genotoxic mechanisms and responses in plants and (ii) the roles of different molecules in modulation of As-induced toxicities in plants. We also provide insight on some important research gaps that need to be filled to advance our scientific understanding in this area of research on As in soil-plant systems.

Seaweed Phenolics: From Extraction to Applications.

Abstract: Seaweeds have attracted high interest in recent years due to their chemical and bioactive properties to find new molecules with valuable applications for humankind. Phenolic compounds are the group of metabolites with the most structural variation and the highest content in seaweeds. The most researched seaweed polyphenol class is the phlorotannins, which are specifically synthesized by brown seaweeds, but there are other polyphenolic compounds, such as bromophenols, flavonoids, phenolic terpenoids, and mycosporine-like amino acids. The compounds already discovered and characterized demonstrate a full range of bioactivities and potential future applications in various industrial sectors. This review focuses on the extraction, purification, and future applications of seaweed phenolic compounds based on the bioactive properties described in the literature. It also intends to provide a comprehensive insight into the phenolic compounds in seaweed.

Regulation of ROS Metabolism in Plants under Environmental Stress: A Review of Recent Experimental Evidence.

Abstract: Various environmental stresses singly or in combination generate excess amounts of reactive oxygen species (ROS), leading to oxidative stress and impaired redox homeostasis. Generation of ROS is the obvious outcome of abiotic stresses and is gaining importance not only for their ubiquitous generation and subsequent damaging effects in plants but also for their diversified roles in signaling cascade, affecting other biomolecules, hormones concerning growth, development, or regulation of stress tolerance. Therefore, a good balance between ROS generation and the antioxidant defense system protects photosynthetic machinery, maintains membrane integrity, and prevents damage to nucleic acids and proteins. Notably, the antioxidant defense system not only scavenges ROS but also regulates the ROS titer for signaling. A glut of studies have been executed over the last few decades to discover the pattern of ROS generation and ROS scavenging. Reports suggested a sharp threshold level of ROS for being beneficial or toxic, depending on the plant species, their growth stages, types of abiotic stresses, stress intensity, and duration. Approaches towards enhancing the antioxidant defense in plants is one of the vital areas of research for plant biologists. Therefore, in this review, we accumulated and discussed the physicochemical basis of ROS production, cellular compartment-specific ROS generation pathways, and their possible distressing effects. Moreover, the function of the antioxidant defense system for detoxification and homeostasis of ROS for maximizing defense is also discussed in light of the latest research endeavors and experimental evidence.