Aluminum nitrate nonahydrate

Sodium hydroxide was purchased from Guangfu Technology Development Co., Ltd. (Tianjin, China). Hydrochloric acid was obtained from Sanhe Chemical Reagent Co., Ltd. (Yantai, China). Sodium acetate anhydrous was acquired from Guangcheng Chemical Reagent Co., Ltd. (Tianjin, China). 2,2-Diphenyl-1-picrylhydrazyl (DPPH, 96% purity) and 2,4,6-tris(2-pyridyl)-s-triazine (TPTZ, 99% purity) were supplied by RHAWN Chemical Reagent Co., Ltd. (Shanghai, China). Ethanol and acetic acid were bought from Fuyu Fine Chemical Co., Ltd. (Tianjin, China). Aluminum nitrate nonahydrate and rutin hydrate (analytical reference) were purchased from Macklin Biochemical Co., Ltd. (Shanghai, China). Sodium nitrite, iron (Ⅲ) chloride hexahydrate and iron (Ⅱ) sulfate heptahydrate were supplied by Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Distilled water was provided by Chengda Distilled Water Co., Ltd. (Qingdao, China). All other chemicals and reagents used in this study were of analytical reagent grade.

Chitosan (CS) (Mw: 5 × 10⁵ g/mol, degree of deacetylation: 95%), N, N-methylenebisacrylamide (BIS), arsenazo III and lanthanum nitrate hexahydrate were purchased from Aladdin Biochemical Technology Co., Ltd. (Shanghai, China). NIPAM was purchased from Tokyo Chemical Industry Co., Ltd. (TCI, Tokyo, Japan). Sodium hydroxide was purchased from Silong Science Co. Ammonium persulfate (APS) and nitric acid were purchased from Guangzhou Chemical Reagent Factory (Guangzhou, China). Copper nitrate, iron nitrate nonahydrate, and aluminum nitrate nonahydrate were purchased from Shanghai Macklin Biochemical Technology Co. (Shanghai, China). All the reagents were used as received.

Hibiscus manihot L. was provided and identified by Yulin Xinbang Pharmaceutical Co., Ltd. (Yulin, China). It was dried in a tray at 65 °C, destemmed and crushed (0.42 mm), and stored at 4 °C for further use.
The fermentation strain was Rhizopus arrhizus JHK31. We obtained it through pressure screening. It is stored in the China Center for Type Culture Collection under the deposit number CCTCC M 2023722.
Reagents including rutin (P98%), vitamin C (P99%), aluminum nitrate nonahydrate (P99%), DPPH (P96%), iron trichloride hexahydrate (P99%), trichloroacetic acid (P99%), dibasic sodium phosphate (P99%), and sodium dihydrogen phosphate (P99%) were from Shanghai Macklin Biochemical Co., Ltd. (Shanghai, China). Shanghai Aladdin Biochemical Technology Co., Ltd. (Shanghai, China) provided other chemicals such as ferrous sulfate (P98%), green vitriol (P99%), sodium hydroxide (P96%), Tris (P99.8%), and salicylic acid (P99%). Shanghai yuanye Bio-Technology Co., Ltd. (Shanghai, China) provided hyperoside (P98%), isoquercitrin (P98%), myricetin (P98%), and quercetin (P98%). Other chemicals such as sodium nitrite (P99%), potassium ferricyanide (P99.5%), and pyrogallol (P99%) were analytically pure. Acetonitrile and methanol were of chromatographic grades. The resin used was LX-83 macroporous resin from Sunresin New Materials Co., Ltd. (Xi’an, China). We used ultrapure water in all experiments.