Ascorbic acid

All chemicals were analytical grade, and were used with no additional purification. Different reagents used for the Ag-NP synthesis (sodium citrate, sodium polystyrene sulfonic acid (SPSS), and silver nitrate) were supplied by Sigma-Aldrich (Munich, Germany), sodium borohydride by Panreac (Barcelona, Spain), and ascorbic acid by Scharlab (Barcelona, Spain). Lead(II) nitrate and cadmium(II) nitrate were purchased from Fluka (Buchs, Switzerland) and VWR International LTD (Radnor, PA, USA), respectively. Totals of 2072 µg·L⁻¹ of Pb(II) and a 1124 µg·L⁻¹ of Cd(II) solutions (corresponding to 10⁻⁵ mol·L⁻¹) were prepared by sequential dilution from a 1000 mg·L⁻¹ stock solution. Metal solutions were standardized by ICP-OES, with a Perkin Elmer model Optima 3200 (Waltham, MA, United States), or by ICP-MS, with an Agilent model 7500cx (Santa Clara, CA, United States). A 0.1 mol·L⁻¹ acetate buffer solution (pH 4.5), prepared from acetic acid (Merck, Munich, Germany) and sodium acetate (Panreac, Barcelona, Spain), was used as electrolyte for constant pH, and to avoid the formation of metal hydroxocomplexes. All solutions were made with ultrapure water (18.2 MΩ·cm) obtained from a Milli-Q plus 185 system (Millipore, Burlington, MA, USA).

2,2-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), butylated hydroxytoluene (BHT), sodium azide, guanidine hydrochloride, tween-40, 1,1-diphenyl-2-picrylhydrazyl (DPPH), Folin Ciocalteau reagent, β-carotene, linoleic acid, glucose, 2,4- dinitrophenylhydrazine (DNPH), 5,5’-Dithiobis-(2-Nitrobenzoic Acid) (DTNB), ammonium molybdate, and polyphenols standards were purchased from Sigma-Aldrich (St. Louis, MO, USA). Hydrogen peroxide (H₂O₂) was purchased from Fluka (Basel, Switzerland). Aluminum chloride (AlCl₃), sodium carbonate (Na₂CO₃), ferric chloride (FeCl₃), potassium persulphate (K₂S₂O₈), potassium ferricyanide (K₃Fe(CN)₆), sulfuric acid, and all solvents were obtained from Merck Life Science (Darmstadt, Germany). Ascorbic acid and trichloracetic acid (TCA) were obtained from Scharlau (Barcelona, Spain).

Ethanol (Sigma Aldrich) and distilled water were used for the extraction of the plant materials. ABTS (2,2′-azino-bis-(3-ethylbenozothiazonline-6-sulfonic acid)), 2,2-diphenyl-1-picrylhydrazyl (DPPH), p-nitrophenyl-α-D-glucopyranoside (pNPG), α-glucosidase, gallic acid, and rutin were purchased from Sigma-Aldrich (St. Louis, USA). Folin-ciocalteu reagent, acarbose, gallic acid, rutin, silicagel, dimethyl sulfoxide, and mEthanol were obtained from Merck (Darmstadt, Germany). Glibenclamide and streptozotocin were purchased from Hi-media (Mumbai). Ascorbic acid was from Scharlau (Scharlab). All of the other chemicals were of analytical grade.

Lemongrass essential oil (LG) was purchased from Plena Natura (Portugal). Citral (95%) was purchased from Acrós-Organics (Madrid, Spain). Food grade sodium alginate and nonionic surfactant Tween80 (Polyoxyethylene sorbitan MonoOleate) were purchased from Sigma–Aldrich Chemic (Steinhein, Germany). Milli-Q filtration system (0.22 µm) was used for obtaining ultrapure water. Calcium chloride was from Sigma–Aldrich Chemic (Steinhein, Germany) and ascorbic acid from Scharlau (Barcelona, Spain). Tryptone Soy Broth (TSB), Tryptone Soy Agar (TSA), Plate Count Agar (PCA), Dicloran Rose-Bengal Chloramphenicol Agar (DRBC) and Potato Dextrose Agar (PDA) were from Bioakar Diagnostics (Beauvais, France) and Phosphate Buffered Saline Tablets and Glycerol from Fisher Scientific (Loughborough, UK).

Iron(III) chloride hexahydrate 98%, iron(II) chloride tetrahydrate 99%, tetraethylortosilicate (TEOS), 98%,hexadecyltrimethylammonium bromide (CTAB), 2-hydroxybenzoic acid, triphenyl phosphite (TPP), tetrabutylammonium bromide (TBAB), 2-aminothiophenol, sodium hydroxide (NaOH), pyridine, 3-isocyanatopropyltriethoxysilane (ICTES), 3-iodopropyltrimethoxysilane (IPTMS), magnesium sulfate, and the nitrate salts of metal cations for fluorescence measurements, that is, Na⁺, K⁺, Ag⁺, Ca²⁺, Mg²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Ba²⁺, Hg²⁺, Pb²⁺, and Al³⁺, were purchased from Sigma Aldrich (Tres Cantos, Spain) and were used as received. Iron(III) nitrate nonahydrate, extra pure sodium acetate anhydrous, sodium hydrogen carbonate, ascorbic acid, and ethylene glycol were purchased from Scharlau (Móstoles, Spain) and were used as received, without further purification. Triethylamine (Et₃N) redistilled 99% was purchased from Fluka (Tres Cantos, Spain) and was used as supplied. Organic solvents such as THF and acetone were purchased from Carlo Erba (Sabadell, Spain) and were distilled and dried over appropriate drying agents. Ethanol was purchased from VWR (Barcelona, Spain) and Milli-Q (Merck-Millipore, Barlington, MA, USA) quality water was used in the experiments.

Cinnamon essential oil was purchased from Zard Band Company. Cumin oil was prepared by the cold press method. Folin–Ciocalteu, 2, 6‐dichloroindophenol and ascorbic acid prepared from Scharlau Company. Sodium carbonate, methanol, acetone, sodium hydroxide, sodium acetate, and hydrochloric acid were supplied from Merck Company.

Alloxan monohydrate and N-acetyl cysteine were purchased from Sigma-Aldrich (Darmstadt, Germany). Ascorbic acid was obtained from Scharlau, and Selenium was obtained from DAEJUNG (Korea). Phenylmethanesulfonyl Fluoride (PMSF) was purchased from (Roth Germany) CAS no: 329-98-6.