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The combination of a proton nuclear magnetic resonance (1H-NMR)-based metabolomics approach and principal component analysis (PCA) was used to differentiate variations of active metabolites in Padina gymnospora subjected to different extraction solvents. Their proximate composition and phytochemical, antioxidant, and antimicrobial activity were also evaluated. A total of 13 metabolites were identified in the different solvents (polar, semipolar, and nonpolar) via 1H-NMR analysis. The present study demonstrated that P. gymnospora brown seaweed was rich in protein, lipid, and carbohydrates. Phytochemical investigation of the different P. gymnospora extracts revealed various secondary metabolites. The most abundant essential amino acid was leucine [5.79 ± 0.06 mg g−1 dry weight (DW)], and the most abundant nonessential amino acid was glutamic acid (8.62 ± 0.04 mg g−1 DW). The presence of metabolites such as alanine, N-phenylacetylphenylalanine, glutamic acid, 2-hydroxyisobutyric acid, sarcosine, and π-methylhistidine in the seaweed extracts was strongly correlated with their level of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical scavenging activity. P. gymnospora appeared to have antibacterial activity against Staphylococcus aureus (ATCC 43,300). The study also revealed P. gymnospora’s potential for use as a rich source of antioxidant agents, implying that commercial cultivation of this seaweed may be incentivized.

Brown seaweed is a promising source of polysaccharides and phenolics with industrial utility. This work reports the development of a green enzyme-assisted extraction method for simultaneously extracting polysaccharides and phenolics from the brown seaweed Padina gymnospora. Different enzymes (Cellulast, Pectinex, and Alcalase), individually and in combination, were investigated, with Alcalase alone showing the highest efficiency for the simultaneous extraction of polysaccharides and phenolics. Yields from Alcalase-assisted aqueous extraction were higher than those obtained using either water alone or conventional ethanol extraction. Alcalase-assisted extraction was subsequently optimized using a response surface methodology to maximize compound recovery. Maximal polysaccharide and phenolic recovery was obtained under the following extraction conditions: a water-to-sample ratio of 61.31 mL/g, enzyme loading of 0.32%, temperature of 60.5 °C, and extraction time of 1.95 h. The extract was then fractionated to obtain alginate-, fucoidan-, and phenolic-rich fractions. Fractions exhibited potent 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity with IC50 values of 140.55 µg/mL, 126.21 µg/mL, and 48.17 µg/mL, respectively, which were higher than those obtained from conventional extraction methods. The current work shows that bioactive polysaccharides and phenolics can be obtained together in high yield through a single aqueous-only green and efficient Alcalase-assisted extraction.

A comprehensive study combined experimental, computational and field experiments was conducted to find out the most appropriate adsorbent system for industrial elimination of congo red (CR) dye from simulated industrial wastewater. Modification of the zeolite (Z) by the Padina gymnospora algae (PG) (Egyptian marine algae) was evaluated in terms of the adsorption capability of the zeolite (Z) to remove CR dye from aqueous solutions. The zeolite/algae composite (ZPG) was fabricated using the wet impregnation technique. Various techniques were used to characterize the PG, Z, and the produced ZPG nanocomposite. Batch experiments were performed to study the influence of various practical variables on adsorption processes. The isotherms and kinetics of dye adsorption were also studied. The newly synthesized ZPG nanocomposite exhibits much higher adsorption capacity, especially at low CR concentrations than that of Z. The computational calculations have shown that owing to the presence of intermolecular interactions, the adsorption of the CR molecule on zeolite surfaces is exothermic, energetically favorable, and spontaneous. For all configurations, increasing the zeolite size does not have a noticeable impact on the adsorption energies. The experimental results revealed that the ZPG nanocomposite can be applied as an economical nanoadsorbent to eliminate anionic dyes from simulated industrial wastewater at low CR dye concentrations. The adsorption isotherm of dye onto Z, PG, and ZPG almost agreed with Langmuir isotherm and pseudo-second-order kinetics. The sorption mechanism was also evaluated using Weber's intra-particle diffusion module. Finally, the field experiments revealed optimistic results for the newly synthesized adsorbent in removing dyes from industrial wastewater with 82.1% efficiency, which in turn confirmed the foundation of new eco-friendly materials that aid in the reuse of industrial wastewater.

Seaweed extracts are used as nutrient supplements, biostimulants, or biofertilizers in agriculture and horticulture to increase plant growth and yield. In this study, we examined the effect of liquid seaweed extracts (LSEs) made from Ulva lactuca, Caulerpa sertularioides, Padina gymnospora, and Sargassum liebmannii as biostimulants on the germination and growth of tomato (Solanum lycopersicum) under laboratory and greenhouse conditions using foliar and soil drench applications of LSEs. We assessed LSEs at different concentrations (0.2, 0.4, and 1.0 %) on germination parameters (percentage, index, mean time, energy, and seedling vigor index) and growth parameters (plumule length, radical length, shoot length, root length, fresh weight, and dry weight) of tomato seedlings. Our results indicate that seeds treated with LSEs of U. lactuca and P. gymnospora at lower concentrations (0.2 %) showed enhanced germination (better response in germination rate associated with lower mean germination time, high germination index and germination energy, and consequently greater seedling vigor and greater plumule and radicle length). Application as a soil drench was found to be more effective in influencing the height of the plant (up to 79 cm) than the foliar spray application (75 cm). Plants receiving LSEs of U. lactuca and P. gymnospora showed increased shoot length, root length, and weight. Furthermore, U. lactuca and P. gymnospora were found to be more successful and better candidates for developing effective biostimulants to improve the growth of tomato plants. This study provides important information on the identification and utilization of Mexican seaweed resources for agriculture and is the first study to report on the uses of these seaweeds as a source of liquid extracts as biostimulants in agriculture.

The worldwide use of plant biostimulants (PBs) represents an environmentally friendly tool to increase crop yield and productivity. PBs include different substances, compounds, and growth-promoting microorganism formulations, such as those derived from arbuscular mycorrhizal fungi (AMF) or seaweed extracts (SEs), which are used to regulate or enhance physiological processes in plants. This study analyzed the physiological, ecological, and biochemical implications of the addition of two PBs, AMF or SE (both alone and in combination), on tomato plants ( Solanum lycopersicum L. cv. “Rio Fuego”). The physiological responses evaluated were related to plant growth and photosynthetic performance. The ecological benefits were assessed based on the success of AMF colonization, flowering, resistance capacity, nonphotochemical quenching (NPQ), and polyphenol content. Biochemical effects were evaluated via protein, lipid, carbohydrate, nitrogen, and phosphorous content. Each PB was found to benefit tomato plants in a different but complementary manner. AMF resulted in an energetically expensive (high ETRMAX but low growth) but protective (high NPQ and polyphenol content) response. AMF + nutritive solution (NS) induced early floration but resulted in low protein, carbohydrate, and lipid content. Both AMF and AMF + NS favored foliar instead of root development. In contrast, SE and SE + NS favored protein content and root development and did not promote flowering. However, the combination of both PBs (AMF + SE) resulted in an additive effect, reflected in an increase in both foliar and root growth as well as protein and carbohydrate content. Moreover, a synergistic effect was also found, which was expressed in accelerated flowering and AMF colonization. We present evidence of benefits to plant performance (additive and synergistic) due to the interactive effects between microbial (AMF) and nonmicrobial (SEs) PBs and propose that the complementary modes of action of both PBs may be responsible for the observed positive effects due to the new and emerging properties of their components instead of exclusively being the result of known constituents. These results will be an important contribution to biostimulant research and to the development of a second generation of PBs in which combined and complementary mechanisms may be functionally designed.

Inhibition of [Beta]-amyloid (A[Beta]) aggregation in the cerebral cortex of the brain is a promising therapeutic and defensive strategy in identification of disease modifying agents for Alzheimer's disease (AD). Since natural products are considered as the current alternative trend for the discovery of AD drugs, the present study aims at the evaluation of anti-amyloidogenic potential of the marine seaweed Padina gymnospora. Prevention of aggregation and disaggregation of the mature fibril formation of A[Beta] 25-35 by acetone extracts of P. gymnospora (ACTPG) was evaluated in two phases by Thioflavin T assay. The results were further confirmed by confocal laser scanning microscopy (CLSM) analysis and Fourier transform infrared (FTIR) spectroscopic analysis. The results of antiaggregation and disaggregation assay showed that the increase in fluorescence intensity of aggregated A[Beta] and the co-treatment of ACTPG (250 Mg/ml) with A[Beta] 25-35, an extensive decrease in the fluorescence intensity was observed in both phases, which suggests that ACTPG prevents the oligomers formation and disaggregation of mature fibrils. In addition, ACTPG was subjected to column chromatography and the bioactivity was screened based on the cholinesterase inhibitory activity. Finally, the active fraction was subjected to LC-MS/MS analysis for the identification of bioactive compounds. Overall, the results suggest that the bioactive compound alpha bisabolol present in the alga might be responsible for the observed cholinesterase inhibition with the IC50 value < 10 Mg/ml for both AChE and BuChE when compared to standard drug donepezil (IC50 value < 6 Mg/ml) and support its use for the treatment of neurological disorders.

Biostimulants such as seaweed extracts are widely used to stimulate plant growth and crop productivity under optimal or stressful conditions, constituting a sustainable strategy to mitigate the impacts of abiotic stress on plant performance. In this study, a growth experiment was conducted to evaluate the effects of an aqueous extract from the seaweed Padina gymnospora on the physiological, biochemical, and molecular characteristics of Solanum lycopersicum under salt stress. The experiment included four treatments: 1) control plants, 2) plants irrigated with 300 mM NaCl solution, 3) plants treated with the P. gymnospora extract, and 4) plants treated with the P. gymnospora extract and irrigated with 300 mM NaCl solution. Salt stress increased the activity of antioxidant enzymes (catalase and superoxide dismutase) and resulted in the overaccumulation of the osmolyte proline and flavonoids while enhancing photosynthetic performance and chlorophyll content. In addition, treatment with P. gymnospora extract increased total reducing sugars and phenols in salt-stressed plants, which was correlated with DPPH and ABTS antioxidant activity. The induction of stress-responsive genes, such as SlHB7, SlSOD1, SlRD29 , and SlHKT, appears to be a major factor modulating the responses to P. gymnospora extract application in tomato plants. The results of this study demonstrate that the application of P. gymnospora to tomato plants attenuated the damage caused by salt stress. It is essential to continue studying the potential of seaweed extracts to mitigate stress in plants, given the promising agricultural applications of these novel biostimulants.

Although marine seaweeds have been used as biostimulants since the beginning of modern agriculture, studies have only recently focused on the ability of seaweed extracts and their polysaccharides to enhance growth of plants. In this work, two bioassays were carried out to study the growth-promoting activity of seaweed extracts and polysaccharide-enriched extracts from Ulva lactuca and Padina gymnospora , obtained in neutral and alkaline conditions. Initially, the effect of seaweed extracts and polysaccharide-enriched extracts on seed germination and growth-promoting activity on tomato ( Solanum lycopersicum cv. Río Grande) plants under in vitro conditions was studied. Half-strength Murashige-Skoog (MS) medium with or without sucrose was supplemented with different concentrations of seaweed extracts (2, 4, and 10 mg mL −1 ) or polysaccharide-enriched extracts (0.2, 0.4, and 1.0 mg mL −1 ). The parameters evaluated were germination percentage, radicle and shoot length, and dry weight. In a second experiment, polysaccharide-enriched extracts at 1.0 mg mL −1 and indole-3-butyric acid as the control were studied for root inducer activity in mung bean ( Vigna radiata ). The majority of seaweed extracts had an inhibitory effect on seed germination. However, a significant effect ( P  ≤ 0.05) on tomato seedling growth (except for dry weight) was shown with seaweed extracts at 2 mg mL −1 included in half-strength MS medium with sucrose (30 g L −1 ). Moreover, 10 mg mL −1 neutral and alkaline seaweed extracts had an inhibitory effect on the parameters evaluated. In contrast, polysaccharide-enriched extracts obtained from U. lactuca and P. gymnospora promoted germination and stimulated growth of tomato plants compared to the controls. Additionally, treatment of mung bean hypocotyl cuttings with polysaccharide-enriched extracts of U. lactuca and P. gymnospora induced rooting more rapidly and in greater number compared to the controls. These results provide evidence that polysaccharide-enriched extracts act as an effective growth-promoting treatment.

The in vitro antioxidant activities of the following six sulfated polysaccharides were investigated: iota, kappa and lambda carrageenans, which are widely used in the food industry, fucoidan (homofucan) from the edible seaweed Fucus vesiculosus and fucans (heterofucans) F0.5 and F1.1 from the seaweed Padina gymnospora. With respect to the inhibition of superoxide radical formation, fucoidan had an IC₅₀ (the half maximal inhibitory concentration) of 0.058 mg·mL-¹, while the IC₅₀ for the kappa, iota and lambda carrageenans were 0.112, 0.332 and 0.046 mg·mL-¹, respectively. All of the samples had an inhibitory effect on the formation of hydroxyl radicals. The results of peroxidation tests showed that fucoidan had an IC₅₀ of 1.250 mg·mL-¹ and that the kappa, iota and lambda carrageenans had an IC₅₀ of 2.753 and 2.338 and 0.323 mg·mL-¹, respectively. Fucan fractions showed low antioxidant activity relative to fucoidan. These results clearly indicate the beneficial effect of algal polysaccharides as antioxidants.

Brown seaweeds are reported to have high antioxidant activity due to the rich composition in phenolic compounds. In this way, they present potential as functional ingredients and additives for food, feed, cosmeceutical and pharmaceutical industries. The objective of this study was to evaluate the antioxidant potential of methanolic and aqueous extracts of three species of brown algae by five in vitro assays, in order to contribute to screening of functional foods ingredients, and to the search for natural antioxidants from marine alga biomass matrix. The ABTS, DPPH, FRAP and iron-chelating assays were used for analysis of antioxidant activity, and the Folin-Ciocalteu assay for the quantification of total phenolic compounds. The methanolic and aqueous extracts of Padina gymnospora and Sargassum cymosum showed up to 50% of antioxidant potential for the five assays, and Chnoospora minima presented antioxidant potential up to 50% only for ABTS assay. Comparing the extracts, aqueous extracts of C. minima and S. cymosum had higher antioxidant activities and phenolic compounds than methanolic extracts, whereas for P. gymnospora the methanolic extracts had greater activities. To integrate the results of antioxidant potential, a total antioxidant capacity index was calculated, classifying the extract potential in reactivity order. It was verified that the methanolic extract of P. gymnospora had the highest antioxidant activity and content of phenolic compounds, indicating the potential of this species in the search for natural antioxidant substances and suitable candidate for further studies as food and functional ingredients.