Ferric Iron Chelator Research Articles

A review on the phytochemistry and biological activities of Curculigo latifolia Dryand ex. W.Aiton

Curculigo latifolia Dryand. ex W. T. Aiton, from the genus Curculigo, is a medicinal plant traditionally used to treat numerous illnesses such as fever, stomach aches, jaundice, wounds, and inflammation. C. latifolia is a perennial herb that is widely found in tropical and subtropical regions, such as Southeast Asia, Southern China, Bangladesh, Australia, and the Andaman Islands. This review collates the reported studies on the different aspects of C. latifolia from its plant description, nutritional value, phytochemistry, chemical composition, and pharmacological properties. This review aims to identify gaps in the literature and provide useful references for future work on this plant. Previous studies have shown that C. latifolia contains high mineral contents of calcium, iron, and magnesium, which are essential components of human health. Moreover, the plant is rich in phytochemicals, which play a prominent role in various pharmacological activities. The most common compounds identified included curculigoside, crassifoside I, nyasicoside, and curculigine. C. latifolia demonstrated high antioxidant activity through its ability to scavenge superoxide anions, 1,1–diphenyl–2–picrylhydrazyl (DPPH) and 2,2’-azino–bis(3–ethylbenzthiazoline–6–sulfonic acid) (ABTS) radicals, reducing ferric ions to ferrous complexes, iron chelation, and B-carotene bleaching. It was also shown that the roots, stems, and leaves of C. latifolia were effective in exerting antimicrobial activity against several microbial strains, including Bacillus cereus, Bacillus subtillis, Enterobacter aerogenes, Erwinia sp., Klebsiella sp., Pseudomonas sp., Candida albicans, Salmonella choleraesuis and Staphylococcus aureus. Moreover, the root, fruit, leaf, petiole, and rhizome extracts were found to improve glucose uptake and insulin secretion in diabetic rats, suggesting their antidiabetic potential. C. latifolia presents a wide range of medicinal properties that could make it a promising functional food or source of food supplements to prevent nutrition–related or chronic diseases.

Comparative antioxidant activity and phytochemical content of five extracts of Pleurotus ostreatus (oyster mushroom)

Reactive oxygen species reacts with numerous molecules in the body system causing oxidative damage, which requires antioxidants to ameliorate. Pleurotus ostreatus, a highly nutritious edible mushroom, has been reported to be rich in bioactive compounds. This study evaluated the comparative antioxidant activity and phytochemical contents of five extracts of P. ostreatus: aqueous (AE), chloroform (CE), ethanol (EE), methanol (ME) and n-hexane (HE). The phytochemical composition and antioxidant activity of the extracts were determined using standard in-vitro antioxidant assay methods. Results showed that the extracts contained alkaloids, tannins, saponins, flavonoids, terpenoids, phenolics, cardiac glycosides, carbohydrates, anthrocyanins, and betacyanins in varied amounts. CE had the highest flavonoid content (104.83 ± 29.46 mg/100 g); AE gave the highest phenol content of 24.14 ± 0.02 mg/100 g; tannin was highest in EE (25.12 ± 0.06 mg/100 g); HE had highest amounts of alkaloids (187.60 ± 0.28 mg/100 g) and saponins (0.16 ± 0.00 mg/100 g). Antioxidant analyses revealed that CE had the best hydroxyl radical activity of 250% at 100 µg/ml and ferric cyanide reducing power of 8495 µg/ml; ME gave the maximum DPPH activity (87.67%) and hydrogen peroxide scavenging activity (65.58%) at 500 µg/ml; EE had the highest nitric oxide radical inhibition of 65.81% at 500 µg/ml and ascorbate peroxidase activity of 1.60 (iU/l). AE had the best total antioxidant capacity (5.27 µg/ml GAE at 500 µg/ml) and ferrous iron chelating activity (99.23% at 100 µg/ml) while HE gave the highest guaiacol peroxidase activity of 0.20(iU/l). The comparative phytochemical and antioxidant characteristics (IC50) of the extracts followed the order: CE > AE > EE > ME > HE. Overall, chloroform was the best extraction solvent for P. ostreatus. The high content of phenolic compounds, flavonoids, and alkaloids in P. ostreatus makes it a rich source of antioxidants and potential candidate for the development of new therapies for a variety of oxidative stress-related disorders.

Chemical Properties and Antioxidant Activity of Different Extracts from Purslane (Portulaca Oleracea L.)

Purslane (Portulaca oleracea L.) has been known as a medical herb with valuable nutritional and pharmacological properties. Herein, water, methanol, and acetone extracts were prepared from two morphologically different purslane samples, thereafter their content of β-carotene, chlorophyll a and b, total phenolic compounds (TPC), total ‎flavonoids, and total flavonols was evaluated. Additionally, DPPH• scavenging ‎activity and ferrous iron (Fe+2) chelating activity of these extracts were also measured. The acetone extract had the highest amounts of β-carotene (14.16 mg g-1 DW), chlorophyll a (40.46 mg g-1 DW), chlorophyll b (9.94 mg g-1 DW), TPC (51.01 mg GAE g-1 DW), ‎flavonoids (133.23 mg RE g-1 DW), and flavonols (46.94 mg RE g-1 DW). Whereas the lowest values were observed in the water extract, as 0.03 mg g-1 DW, 0.03 mg g-1 DW, 0.06 mg g-1 DW, (34.24 mg GAE g-1 DW, 10.98 mg RE g-1 DW, 3.28 mg RE g-1 DW, respectively. The acetone extract also showed higher DPPH• scavenging ‎activity (IC50 = 57.23 µg mL-1) compared to methanol (IC50 = 65.80 µg mL-1) and water (IC50 = 71.47 µg mL-1) extracts. Regarding the ferrous iron (Fe+2) chelating activity, methanol extract exhibited the highest value followed by water and acetone extracts, being 12.78, 10.20 and 6.08%, respectively. A positive correlation was detected between the DPPH• scavenging activities of the purslane extracts and their content of TPC, flavonoid, flavonol, β-carotene, chlorophyll a, and chlorophyll b. On the other hand, there was no significant correlation between chelating activity of the extracts and their content of β-carotene, chlorophyll a, TPC, flavonoids, flavonols, and DPPH scavenging activity. Purslane extracts could be suggested as a natural antioxidant substance for many pharmaceutical and food applications.

Identification of a system for hydroxamate xenosiderophore-mediated iron transport in Burkholderia cenocepacia.

One of the mechanisms employed by the opportunistic pathogen Burkholderia cenocepacia to acquire the essential element iron is the production and release of two ferric iron chelating compounds (siderophores), ornibactin and pyochelin. Here we show that B. cenocepacia is also able to take advantage of a range of siderophores produced by other bacteria and fungi ('xenosiderophores') that chelate iron exclusively by means of hydroxamate groups. These include the tris-hydroxamate siderophores ferrioxamine B, ferrichrome, ferricrocin and triacetylfusarinine C, the bis-hydroxamates alcaligin and rhodotorulic acid, and the monohydroxamate siderophore cepabactin. We also show that of the 24 TonB-dependent transporters encoded by the B. cenocepacia genome, two (FhuA and FeuA) are involved in the uptake of hydroxamate xenosiderophores, with FhuA serving as the exclusive transporter of iron-loaded ferrioxamine B, triacetylfusarinine C, alcaligin and rhodotorulic acid, while both FhuA and FeuA are able to translocate ferrichrome-type siderophores across the outer membrane. Finally, we identified FhuB, a putative cytoplasmic membrane-anchored ferric-siderophore reductase, as being obligatory for utilization of all of the tested bis- and tris-hydroxamate xenosiderophores apart from alcaligin.

Investigation of in vitro antidiabetic and antioxidant activity of hawthorn vinegar obtained from Endemic Crataegus tanacetifolia (Poir.) Pers.

In this study, the in vitro antidiabetic, antioxidant activity and total flavonoid content (TFC) and total phenolic content (TPC) of vinegar obtained from endemic Crataegus tanacetifolia (Lam.) Pers. (Rosaceae), (hawthorn) were examined. The hawthorn vinegar obtained from Malatya province (MS) and the vinegar (TS) obtained from Konya were used as study material. Their antidiabetic activity was determined by α-amylase and α-glucosidase inhibitory methods. Antioxidant activities were determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and ferrous iron chelating (FCA) assays. The absorbance were read in the Elisa reader and evaluated with Excel and GraphPad programs. The MS has been found to have higher α- amylase (95.12± 3.71%) and α-glucosidase inhibitory (81.62 ± 0.33%) effects. The TS demonstrated (94.13 ± 3.85%) α-amylase and (75.35 ± 2.19%) α-glucosidase inhibitory activity, respectively. The TPC was found to be in TS (467.59 ± 6.73) mg GAE/mL MS (328.46 ± 5.50) mg GAE/mL. The TFC was found as (1.94 ± 10.36) mg CE/mL and (1.32 ± 10.96) mg CE/mL in TS and MS vinegar, respectively. The FCA was found to be in TS (33.37 ± 0.53%) MS (31.08 ± 10.87%). The DPPH radical scavenging activity was found as (73.82 ± 2.12%) in TS and (80.12 ± 4.45%) in MS. ABTS radical scavenging activity was found to be the highest in TS with (82.51± 0.78%) and in MS found as (78.65 ± 0.55%). The antidiabetic, antioxidant activity, TPC and TFC determinations of these vinegars were performed for the first time with these methods.

Sulfated iota-carrageenan from marine alga Agardhiella ramosissima prevents gastric injury in rodents via its antioxidant properties

In the present study, the gastroprotective effect of a sulfated polysaccharide isolated from marine alga Agardhiella ramosissima (SP-Ar) was investigated against alcoholic gastropathy. Gastric physiological functions and in vitro antioxidant activity also were studied. It was found that SP-Ar significantly reduced macroscopic injury and histologically maintained the architecture of gastric epithelium altered by ethanol, with maximum effect at 90 mg/kg. Importantly, animals treated with SP-Ar also had preservation of oxidative status, with reduction of nonprotein sulfhydryl groups (NP-SH) consumption and malondialdehyde (MDA) production, reduced vascular permeability, besides preventing gastric hemorrhage. In addition, SP-Ar administration did not modify gastric secretion or emptying. In vitro antioxidant data showed that SP-Ar presented high total antioxidant activity, DPPH radical scavenging, and ferrous iron chelating capacity. It was observed that SP-Ar protected gastric mucosa against alcoholic gastropathy by preventing the formation or neutralizing free radicals, associated with its intrinsic antioxidant activity. In this regard, this macromolecule should have possible application as a new therapeutic alternative or food additive to increase gastric mucosa defense.

Transferrin receptor 1 promotes hepatocellular carcinoma progression and metastasis by activating the mTOR signaling pathway.

Aberrant iron metabolism is commonly observed in multiple tumor types, including hepatocellular carcinoma (HCC). However, as the key regulator of iron metabolism involved in iron absorption, the role of transferrin receptor (TFRC) in HCC remains elusive. The mRNA and protein expression of TFRC were evaluated in paired HCC and adjacent non-tumor specimens. The correlation between TFRC level and clinicopathological features or prognostic significance was also analyzed. The role of TFRC on biological functions was finally studied in vitro and in vivo. The TFRC level was remarkably upregulated in HCC tissues compared to paired peritumor tissues. Overexpressed TFRC positively correlated with serum alpha-fetoprotein, carcinoembryonic antigen, and poor tumor differentiation. Multivariate analysis demonstrated that upregulated TFRC was an independent predictive marker for poorer overall survival and disease-free survival in HCC patients. Loss of TFRC markedly impaired cell proliferation and migration in vitro and notably suppressed HCC growth and metastasis in vivo, while overexpression of TFRC performed an opposite effect. Mechanistically, the mTOR signaling pathway was downregulated with TFRC knockdown, and the mTOR agonist MHY1485 completely reversed the biological inhibition in HCC cells caused by TFRC knockdown. Furthermore, exogenous ferric citrate (FAC) or iron chelator reversed the changed biological functions and signaling pathway expression of HCC cells caused by TFRC knockdown or overexpression, respectively. Our study indicates that TFRC exerts an oncogenic role in HCC and may become a promising therapeutic target to restrain HCC progression.

DES-based microwave- and ultrasound-assisted extraction of natural products from Rumex hastatus as per response surface methodology

Rumex hastatus D. Don is a medicinal wild herb that abundantly grows in many parts of the world. The current work explores the extraction of its polyphenolic and antioxidant compounds using glycerol-choline chloride deep eutectic solvent and two modern techniques, ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE). The optimization was done as per the response surface methodology. Six responses were studied including total phenolic content (TPC), total flavonoid content (TFC), total condensed tannin content (TCT), ferrous iron-chelating (FIC) activity, DPPH radical scavenging activity (RSA), and ferric reducing antioxidant potential (FRAP). The optimal factors for MAE were 10 s extraction time, 229.40 W power, 40 mL/g SSR (solvent-to-solid ratio) and 60 % DES concentration with the predicted TPC, TFC, TCT, FIC, RSA and FRAP as 64.46 mg GAE/g PM, 155.78 mg RE/g PM, 129.73 mg CE/g PM, 51.46 mg EDTAE/g PM, 235.84 mg AAE/g PM and 129.14 mg AAE/g PM, respectively. For UAE, the predicted optimal factors were 24.30 min sonication time, 47 °C extraction temperature, 40 mL/g SSR and 60 % DES concentration with the predicted TPC, TFC, TCT, FIA, RSA, and FRAP as 56.54 mg GAE/g PM, 148.24 mg RE/g PM, 155.60 mg CE/g PM, 57.83 mg EDTAE/g PM, 240.56 mg AAE/g PM and 111.71 mg AAE/g PM, respectively. Both the models were strongly supported by the validation study with minimal % errors; 2.53–6.38 % for MAE and 1.14–5.30 % for UAE. MAE was more efficient than UAE in terms of time input and recovery of total polyphenols. Therefore, the method based on DES-MAE can safely be recommended for use on an industrial level for obtaining bioactives from R. hastatus.

Anti-cancer effects of the extracts of broad and spirale cultivars of Codiaeum variegatum (L.) Blume on MCF-7, HepG2, and HeLa cell lines

Introduction: Codiaeum variegatum (L.) Blume is a well-known ornamental foliage plant used as a vegetable in northern Thailand, and it is the source of numerous bioactive substances. This work explored the effects of leaf extracts of broad (BCE) and spirale (SCE) cultivars of C. variegatum on three cancer cells, including human breast, human liver, and human cervical cancer cells. Methods: Ethanolic plant extracts were prepared, and then, 2,2-diphenyl-1-picryhydrazyl (DPPH), ferrous iron chelating, and lipid peroxidation assays were used to examine the flavonoid and phenolic compounds. The proliferative inhibition, growth, and migration of MCF-7, HepG2, and HeLa cancer cells, as a result of exposure to the extracts, were investigated. The extracts were investigated for their anti-cancer activities using sulforhodamine B (SRB), clonogenic, and wound-healing methods. Results: The data demonstrated that BCE and SCE contained high phenolic compounds. However, both extracts showed inactive anti-oxidant activities. Both extracts had high cytotoxicity on three types of cancer cells in a dose- and time-dependent manner after 24-72 hours of incubation with IC50 values in a range of 208-830 µg/mL. Moreover, the prepared extracts of C. variegatum significantly inhibited colony-forming ability and cell migration on all types of cancer cells. Compared with BCE, SCE showed more potent anti-cancer activities. Conclusion: These findings revealed that SCE had higher anti-cancer activities on MCF-7, HepG2, and HeLa cancer cells than BCE. Consequently, the SCE might be used as an effective chemotherapeutic compound for the prevention and treatment of cancer.

Effects of Phyllanthus emblica leaves and branches mixture on growth performance, oxidative status and intestinal characteristics in broiler chickens

This study investigated the effect of Phyllanthus emblica leaves and branches mixture (PE) on growth performance, oxidative status and intestinal characteristics in broilers, as well as the in vitro antioxidant potential of PE extract (PEE). As the result of in vitro evaluation, the PEE had a total phenolic compound content of 95.5 ± 2.75 mg of Gallic acid equivalent/g dry weight (DW), and a total flavonoid content of 3.04 ± 0.06 mg of quercetin equivalent/g DW. The PEE exhibited significant antioxidant activity through various mechanisms, including chelation of ferrous iron, reducing power, scavenging 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radicals, inhibition of liposome peroxidation and trolox equivalent antioxidant capacity (TEAC). A total of 320 Ross 308 broilers were randomly allocated into four groups: control, basal diet supplemented with 0.5%, 1%, 2% PE. Each group was fed for 35 d. The results showed that the group fed with 0.5% PE had significantly better weight gain, and improved feed conversion ratio (FCR) compared to the control group. Moreover, each PE group significantly reduced coliform and Clostridium perfringens in the ileum and caecum. Additionally, PE group with 0.5% concentration had significantly higher villus height in the jejunum compared to the other group. Furthermore, compared to the control group, each PE group had significantly lower levels of malondialdehyde (MDA) and higher levels of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activity in the serum. In the peripheral blood mononuclear cells (PBMCs) of chickens, each PE group showed significantly higher mRNA levels of antioxidant-regulated genes, including Nrf2, GST, GCLC, SOD1 and HO-1. In contrast, the expression levels of NOX1 and ROMO1 genes were significantly lower. In conclusion, the inclusion of 0.5% PE in the basal diet could have a positive impact on the growth performance of broilers by modulating intestinal characteristics and oxidative status.

Potential of Nutmeg (<em>Myristica fragrans</em> Houtt) Leaf Extracts as a Source of Functional Ingredients with Antibacterial, Antifungal and Antioxidant Activities

Purpose: The objectives of this study were to evaluate inhibition activities of acetone, chloroform, ethanol and hot water extracts of nutmeg (Myristica fragrans Houtt.) leaves against Salmonella enterica, Listeria monocytogenes, Shigella dysenteriae, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Aspergillus niger and, to assess the in vitro antioxidant activities and to discover the active compound profile of chloroform extract of nutmeg leaf. Research Method: Agar well diffusion and agar disc diffusion methods were used to evaluate the antibacterial activity and the antifungal activity of the extracts respectively. Antioxidant activities of the acetone extract were evaluated through DPPH, FRAP, ABTS+ radical scavenging and Ferrous Iron Chelating assays. The total phenolic content (TPC) of the acetone extract was determined using the Folin-Ciocalteu assay. Findings: All the extracts showed inhibitory activity for the tested bacteria at different intensities and it was found that the selection of the extraction solvent is important to get the maximum inhibition against different bacterium. Acetone and chloroform extract (20%) showed the highest inhibition against A. niger (49.42% and 51.52% respectively). Acetone extract showed strong antioxidant activities, 715.78 ±51.09 in FRAP (mg of Trolox /g of leaves), 65.56±0.93 in DPPH (mg of Ascorbic acid /g of leaves), 31.67± 0.49 in ABTS+ (mg of Trolox equivalent/g of leaves), 10.87±1.85 in Ferrous Ion chelating (mg of EDTA/g of leaves) and, higher percentages of total phenolic content of 895.12 ±44.24 TPC (mg GAE /g of leaves). Myristic acid was detected as the major compound (57.36%) in GC-MS analysis and that may be the major compound responsible that offers a great potential to use as antibacterial, antifungal and antioxidant agent of nutmeg leaf. Originality/ Value: Results revealed that the nutmeg leaf possesses marked biological activities and showed a great potential to use for the management of human pathogenic bacteria, plant pathogenic fungi, and oxidative stress-associated chronic diseases.

In vitro antioxidant activities of Carissa edulis ((Forssk) Vahl) and Pappea capensis (Eckyl. & Zeyh) extracts

Herbal medications are gaining popularity due to their long history of use in traditional medicine. They serve as a reservoir for a diverse array of phytocompounds linked to amelioration of oxidative stress. Oxidative stress is a disturbance in the balance between generation and elimination of reactive species in human body. Moreover, reactive species are implicated in the onset and progression of chronic disorders. The current therapeutic approaches despite showing efficacy are characterized by several limitations such as adverse effects and prohibitive costs. This drives the need to explore alternatives that can inhibit, ameliorate or reverse conditions caused by oxidative stress. Several studies have evaluated antioxidant effects of diverse plant extracts. C. edulis and P. capensis are used as traditional therapy among the African communities to manage oxidative stress-related ailments. However, there is limited research on the antioxidant effects of these medicinal plants. The current study, therefore, sought to evaluate the antioxidant and phytochemical profile, of C. edulis and P. capensis extracts. Samples were collected from Embu County, Kenya. In vitro antioxidant properties of the extracts were evaluated through ferric reduction, Iron chelating, hydroxyl radical, and DPPH radical scavenging activities. Activities of catalase, superoxide dismutase and glutathione reductases of the extracts were further determined. Phytochemical profiles were determined using Liquid Chromatography Mass Spectrophotometer (LC-MS) and Gas Chromatography Mass Spectrophotometer (GC-MS) analyses. The extracts displayed concentration dependent antioxidant activities. Phytochemical analyses revealed presence compounds which are associated with antioxidant activities including flavonoids, phenolics, tocopherols and terpenoids. The findings provide a scientific validation for the folklore use of C. edulis and P. capensis in management of oxidative stress. Nevertheless, there is a need for further purification and characterization of phytochemicals associated with antioxidant activities.

Biological Activity and Chemical Composition of Propolis from Various Regions of Poland.

Propolis is one of the bee products, with multiple biological properties used in numerous applications. The research objective was to determine the chemical composition and biological properties (antibacterial, antifungal, antiviral, antioxidant, and cytoprotective activity) of propolis extracts collected from various regions of Poland. The results indicated that the total content of phenols (116.16-219.41 mg GAE/g EEP) and flavonoids (29.63-106.07 mg QE/g EEP) in propolis extracts depended on their geographic origin. The high content of epicatechin, catechin, pinobanksin, myricetin, and acids: vanillic and syringic in propolis samples was confirmed by chromatographic analysis. Moreover, the presence of caffeic acid phenethyl ester was confirmed in all samples. The origin of propolis also influenced the biological properties of its extracts. The propolis extracts were characterized by moderate DPPH free radical scavenging activity (29.22-35.14%), and relatively low ferrous iron chelating activity (9.33-32.32%). The results indicated also that the propolis extracts showed high activity in the protection of human red blood cells against free radicals generated from 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH). The extracts exhibited diversified activity against the tested pathogenic bacteria and limited activity against fungal strains. The research of selected propolis extracts showed that only 2 of 5 examined samples showed moderate activity against HPV (human papillomaviruses) and the activity depended on its geographical distribution.

Nonribosomal peptide synthetase gene clusters and characteristics of predicted NRPS-dependent siderophore synthetases in Armillaria and other species in the Physalacriaceae.

Fungal secondary metabolites are often pathogenicity or virulence factors synthesized by genes contained in secondary metabolite gene clusters (SMGCs). Nonribosomal polypeptide synthetase (NRPS) clusters are SMGCs which produce peptides such as siderophores, the high affinity ferric iron chelating compounds required for iron uptake under aerobic conditions. Armillaria spp. are mostly facultative necrotrophs of woody plants. NRPS-dependent siderophore synthetase (NDSS) clusters of Armillaria spp. and selected Physalacriaceae were investigated using a comparative genomics approach. Siderophore biosynthesis by strains of selected Armillaria spp. was evaluated using CAS and split-CAS assays. At least one NRPS cluster and other clusters were detected in the genomes studied. No correlation was observed between the number and types of SMGCs and reported pathogenicity of the species studied. The genomes contained one NDSS cluster each. All NDSSs were multi-modular with the domain architecture (ATC)3(TC)2. NDSS clusters of the Armillaria spp. showed a high degree of microsynteny. In the genomes of Desarmillaria spp. and Guyanagaster necrorhizus, NDSS clusters were more syntenic with NDSS clusters of Armillaria spp. than to those of the other Physalacriaceae species studied. Three A-domain orthologous groups were identified in the NDSSs, and atypical Stachelhaus codes were predicted for the A3 orthologous group. In vitro biosynthesis of mainly hydroxamate and some catecholate siderophores was observed. Hence, Armillaria spp. generally contain one highly conserved, NDSS cluster although some interspecific variations in the products of these clusters is expected. Results from this study lays the groundwork for future studies to elucidate the molecular biology of fungal phyto-pathogenicity.

Optimization of solvent-free microwave-assisted extraction of antioxidant compounds from Lagenaria siceraria fruit by response surface methodology

Abstract Lagenaria siceraria (bottle gourd) fruit is highly celebrated for its nutritional as well as therapeutic properties. The present study was undertaken with the aim of exploring an efficient green solvent-free microwave-assisted extraction method for bioactives from this fruit. Optimization was done according to response surface methodology (RSM), where microwave power (W) and time (s) were independent factors, and percent extraction yield, total phenolic content (TPC), total flavonoid content (TFC), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, ferric reducing antioxidant potential (FRAP) and iron chelating activity (ICA) were the responses. TPC, TFC, DPPH radical scavenging activity, FRAP and ICA were highest at 480 W and 60 s. The TPC was 288.9 mg GAE · g−1 DW (milligram gallic acid equivalent per gram dry weight), TFC was 214.1 mg RE · g−1 (rutin equivalent per gram DW), anti-radical activity was 32.96%, FRAP was 289.7 mg AAE · g−1 (mg ascorbic acid equivalents per gram) and ICA was 19.52%. The results of the study thus demonstrate that the solvent-free microwave-assisted extraction method, which utilised an optimum power of 480 W and a time of 60 s, is an effective and green method for extraction of antioxidant compounds from bottle gourd fruit.

The effects of nitrogen application on the growth, photosynthesis, and antioxidant activity of Amaranthus viridis

Amaranthus viridis is a functional food due to its antioxidant activity. The aim of this study was to investigate the responses of photosynthesis, growth, and antioxidant properties in A. viridis to nitrogen (N) applications. A. viridis plants were cultivated under low N (LN), medium N (MN), and high N (HN), and harvested at the reproductive phase. The dry mass and plant height of A. viridis plants increased with elevated N, and the dry mass of HN was saturated. Net photosynthetic rate, stomatal conductance, and water-use efficiency in the leaves at HN were strengthened. Meanwhile, under HN, chlorophylls (Chl), their precursors, and degradation intermediates in the leaves were highly accumulated, and the minor route of Chl degradation pathway was induced dramatically. However, 2,2-diphenyl-1-picrylhydrazyl radical-scavenging, ferrous iron-chelating, and reducing power in the extracts were reduced under HN. Conclusively, an appropriate N application balanced the yield and antioxidant properties of A. viridis.

Effects of Spray Drying and Freeze Drying on Physicochemical Properties, Antioxidant and ACE Inhibitory Activities of Bighead Carp (Aristichthys nobilis) Skin Hydrolysates.

The physicochemical, structural properties, antioxidant, and angiotensin I-converting enzyme (ACE) inhibitory activities of fish skin protein hydrolysate (SPH) that were freeze-dried (SPH-FD) and spray-dried (SPH-SD) were investigated. SPH-SD showed abundant volatile compounds, higher DPPH radical scavenging activity and ferrous iron chelating activity than SPH-FD, while the ABTS radical scavenging activity and ACE inhibitory activity were not influenced by the drying method. Amino acid compositions showed a higher proportion of proline and hydroxyproline residues in SPH-FD. The major molecular weights were both distributed below 1000 Da. SPH-SD had spherical structures, while SPH-FD had glass shard-like structures. The results indicated that the drying method could affect the physicochemical properties of hydrolysates, and SPH-SD showed potential prospects in developing functional fortified foods.

Changes in antioxidant activity of fresh marine macroalgae from the Canary Islands during air-drying process

Marine macroalgae develop structurally distinct molecules that have been long recognized as an important source of natural products, e.g., bioactive compounds and antioxidants, such as carotenoids, amino acids, proteins, lipids, vitamins and polyphenols, with promising properties as anticoagulant, anti-proliferative and antimicrobial. In this study we analyzed the antioxidant activity of 24 fresh methanolic extracts from marine macroalgae from the Canary Islands. Additionally, the effects of air-drying process in the antioxidant activity were also evaluated. Plant material was collected in three locations on the island of Tenerife. Total antioxidant activity methods included DPPH-free radical scavenging activity and ferrous iron chelating activity. Phytoconstituents evaluated were total carotenoids, proline, phenols, flavonoids and condensed tannins content. Our results indicated that from fresh material, species Cladophora liebetruthii, Dasycladus vermicularis and Dictyopteris polypodioides presented the highest scavenging activity, supported by high correlation with phenolics and flavonoids content, however, in air-dry extracts, Anadyomene saldanhae and D. polypodioides showed the highest antioxidant potential, correlated with a high phenolic compounds content. Asteronema breviarticulatum and D. polypodioides presented a high content of carotenoids in fresh and air-dry state. The highest ferrous iron chelating activity (>60 %) was recorded in extracts from fresh material in Grateloupia imbricata and Lophocladia trichoclados. However, only L. trichoclados was able to maintain this high activity after air-drying supported by a high proline content. A. breviarticulatum was the species that showed the highest condensed tannins content both in fresh and dried extracts. The study revealed that fresh extracts of D. vermicularis, D. polypodioides and L. trichoclados possess promising properties as raw materials to obtain biologically active substances in alimentary and pharmaceutical industry. Besides, these properties were maintained after the air-drying period in the last two species, which makes them species of great interest to be used under drying preservation methods.

Engineering siderophore production in Pseudomonas to improve asbestos weathering.

SummaryIron plays a key role in microbial metabolism and bacteria have developed multiple siderophore‐driven mechanisms due to its poor bioavailability for organisms in the environment. Iron‐bearing minerals generally serve as a nutrient source to sustain bacterial growth after bioweathering. Siderophores are high‐affinity ferric iron chelators, of which the biosynthesis is tightly regulated by the presence of iron. Pyoverdine‐producing Pseudomonas have shown their ability to extract iron and magnesium from asbestos waste as nutrients. However, such bioweathering is rapidly limited due to repression of the pyoverdine pathway and the low bacterial requirement for iron. We developed a metabolically engineered strain of Pseudomonas aeruginosa for which pyoverdine production was no longer repressed by iron as a proof of concept. We compared siderophore‐promoted dissolution of flocking asbestos waste by this optimized strain to that by the wild‐type strain. Interestingly, pyoverdine production by the optimized strain was seven times higher in the presence of asbestos waste and the dissolution of magnesium and iron from the chrysotile fibres contained in flocking asbestos waste was significantly enhanced. This innovative mineral weathering process contributes to remove toxic iron from the asbestos fibres and may contribute to the development of an eco‐friendly method to manage asbestos waste.

Roles of SmeYZ, SbiAB, and SmeDEF Efflux Systems in Iron Homeostasis of Stenotrophomonas maltophilia.

ABSTRACTStenotrophomonas maltophilia, a nonfermenting Gram-negative rod, is frequently isolated from the environment and is emerging as a multidrug-resistant global opportunistic pathogen. S. maltophilia harbors eight RND-type efflux pumps that contribute to multidrug resistance and physiological functions. Among the eight efflux pumps, SmeYZ pump is constitutively highly expressed. In our previous study, we demonstrated that loss-of-function of the SmeYZ pump results in pleiotropic phenotypes, including abolished swimming motility, decreased secreted protease activity, and compromised tolerance to oxidative stress and antibiotics. In this study, we attempted to elucidate the underlying mechanisms responsible for ΔsmeYZ-mediated pleiotropic phenotypes. RNA-seq transcriptome analysis and subsequent confirmation with qRT-PCR revealed that smeYZ mutant experienced an iron starvation response because the genes involved in the synthesis and uptake of stenobactin, the sole siderophore of S. maltophilia, were significantly upregulated. We further verified that smeYZ mutant had low intracellular iron levels via inductively coupled plasma mass spectrometry (ICP-MS). Also, KJΔYZ was more sensitive to 2,2′-dipyridyl (DIP), a ferrous iron chelator, in comparison with the wild type. The contribution of SmeYZ, SmeDEF, and SbiAB pumps to stenobactin secretion was suggested by qRT-PCR and further verified by Chrome Azurol S (CAS) activity, iron source utilization, and cell viability assays. We also demonstrated that loss-of-function of SmeYZ led to the compensatory upregulation of SbiAB and SmeDEF pumps for stenobactin secretion. The overexpression of the SbiAB pump resulted in a reduction in intracellular iron levels, which may be the key factor responsible for the ΔsmeYZ-mediated pleiotropic phenotypes, except for antibiotic extrusion.IMPORTANCE Efflux pumps display high efficiency of drug extrusion, which underlies their roles in multidrug resistance. In addition, efflux pumps have physiological functions, and their expression is tightly regulated by various environmental and physiological signals. Functional redundancy of efflux pumps is commonly observed, and mutual regulation occurs among these functionally redundant pumps in a bacterium. Stenotrophomonas maltophilia is an opportunistic pathogen that shows intrinsic multi-drug resistance. In this study, we demonstrated that SmeYZ, SbiAB, and SmeDEF efflux pumps of S. maltophilia display functional redundancy in siderophore secretion. Inactivation of smeYZ led to the upregulation of smeDEF and sbiAB. Unexpectedly, sbiAB overexpression resulted in the reduction of intracellular iron levels, which led to pleiotropic defects in smeYZ mutant. This study demonstrates a previously unidentified connection between efflux pumps, siderophore secretion, and intracellular iron levels in S. maltophilia.