A highly efficient nanoscale tapioca starch prepared by high-speed jet for Cu2+ removal in simulated industrial effluent.

BACKGROUND: Nanoscale tapioca starch (NTS) was successfully developed by high-speed jet in our previous study. In this study, the adsorption capacity of Cu2+ onto NTS was further discussed. The optimal adsorption conditions (pH, contact time, contact temperature, initial Cu2+ concentration, and adsorbent concentration), adsorption kinetics, isotherms, and thermodynamic were also evaluated. RESULTS: The results showed that NTS exhibited excellent performance in adsorption of Cu2+ , with adsorption capacities of 122.31 mg g-1 for Cu2+ (pH 7, 0.04 g L-1 , 0.2 g L-1 , 313.15 K and 10 min). The pseudo-second-order and Langmuir isotherms models could be used to explain the adsorption kinetics and adsorption equilibrium, respectively. The thermodynamic results showed that the adsorption process was spontaneous and endothermic with an increase in entropy. Cu2+ was adsorbed onto NTS, which was confirmed by energy dispersive spectrometry analysis. CONCLUSION: These findings indicated that NTS might be an effective, environment-friendly and renewable bio-resource adsorbent for removing heavy metals in industrial effluent. © 2021 Society of Chemical Industry.

Chemical composition and evaluation of antioxidant activities, antimicrobial, and anti-melanogenesis effect of the essential oils extracted from Dalbergia pinnata (Lour.) Prain.

ETHNOPHARMACOLOGICAL RELEVANCE: Dalbergia pinnata (Lour.) Prain (D. pinnata) is a plant widely distributed in tropical and subtropical regions of Asia, Africa, and the Americas. In humans, it is used in the prevention and treatment of diseases such as respiratory system, digestive system, cardiovascular and cerebrovascular diseases. AIM OF THE STUDY: This study was aim to evaluate chemical composition, antioxidant activities, antimicrobial, and anti-melanogenesis properties of Essential oils (EO) from D. pinnata. MATERIALS AND METHODS: In this paper, the EO of D. pinnata were extracted using the supercritical CO2 extraction method and purified by molecular distillation. The volatile compounds of EO were characterized using Gas Chromatography-Mass Spectrometer (GC-MS). The antioxidant activities were evaluated by the methods of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. And two Gram-positive bacteria, three Gram-negative bacteria and a fungus were employed to evaluate the antimicrobial activity. The zebrafish was used as experimental model to evaluate the anti-melanogenesis effect of the EO from D. pinnata. RESULTS: The EO of D. pinnata were obtained in a yield of 4.75% (v/w) calculated on dry weight basis. 14 volatile compounds could be detected and the predominant components include elemicin (91.06%), methyl eugenol (3.69%), 4-allyl-2,6-dimethoxyphenol (1.16%), and whiskey lactone (0.55%). The antioxidant assay showed that the EO could scavenge DPPH (IC50 values of 0.038 mg/mL) and ABTS (IC50 value of 0.032 mg/mL) free radical, indicating that the EO had strong antioxidant activity. The results of antimicrobial test showed that Staphylococcus aureus was most sensitive to EO with minimal inhibitory concentration (MIC) of 0.78 µL/mL, followed by Streptococcus pyogenes (6.25 µL/mL) and Candida albicans (12.5 µL/mL). Gram-negative strains, including Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium, were slightly affected by the EO. Additionally, EO from D. pinnata could reduce tyrosinase activity and melanin synthesis of zebrafish embryos in dose-dependent manner. And EO exhibited the more obvious anti-melanogenic effect compared with the positive control arbutin at the same dose (30 mg/L). CONCLUSIONS: Our results validated the main activities attributed to D. pinnata for its antimicrobial and antioxidant. In addition, the potent inhibitory impacts of EO on the pigmentation provides a theoretical basis for the in-depth study of the EO from D. pinnata and their application in pharmaceutical and cosmetic industries.