Evaluation of electro-assisted phytoremediation (EAPR) system for heavy metal removal from synthetic leachate using Pistia stratiotes.

The highest waste generated in Malaysia is composed of municipal solid waste, which is mainly managed by landfilling. Heavy metals in leachate generated from landfill could have caused hazardous effects to human and environment. EAPR has been increasingly applied to treat soil and wastewater. This technique serves as a potential tool for remediation of real leachate. Metals (Mn, Cd, Fe, Ni, Pb, Zn) uptake by Pistia stratiotes were evaluated via flame atomic adsorption spectrophotometer. Pb and Fe could be the elements that were more efficiently removed by P. stratiotes in the EAPR system. The removal efficiency was 59.86 ± 9.98 and 56.56 ± 18.08% for Pb and Fe, respectively. EAPR significantly reduced the BOD (9.37 ± 2.36 mg/L), color (120.00 ± 5.77 PtCo), and turbidity (25.50 ± 11.96 NTU) of synthetic leachate. An obvious accumulation of heavy metals was observed at roots based on BCF and TF values. BCF values of Pb (18,999.06 ± 8,321.76) and Fe (16,090.81 ± 5,844.36) in the EAPR system were more than 103, which indicates that P. stratiotes is a hyperaccumulator. Further study on the upregulated genes is needed to comprehend the molecular basis of heavy metal stress tolerance.

EAPR greatly reduced heavy metals, BOD, color, and turbidity of synthetic leachate. The use of water lettuce in EAPR could be another plant alternative for potential remediation of real leachate which is extremely difficult to be treated.

Multiple shoot bud induction and plant regeneration studies of Pongamia pinnata.

Pongamia pinnata is a legume plant which has great potential to be used as a biofuel feedstock. Conventional propagation of P. pinnata was found to be inefficient for mass propagation. Employing plant tissue culture techniques for micropropagation and further plant improvement of P. pinnata will be the right path to fulfill future challenges in biofuel production. This study aimed to establish a plant regeneration system for potential micropropagation and genetic manipulation of P. pinnata in future. In vitro nodal explants were used and Woody Plant Medium (WPM) containing 30 µM 6-benzylaminopurine (BAP) and 1 mM phloroglucinol (PG) was able to induce higher frequency of multiple shoot buds compared to other media investigated in this study. For shoot regeneration study, WPM containing 15 µM of zeatin and 1 mM PG was able to induce longer shoots while rooting of the regenerated shoots was enhanced by WPM supplemented with indole-3-butyric acid (IBA) in combination with silver thiosulphate (STS). A simple and effective acclimatisation protocol was established with very high survival frequency of regenerated plantlets. Root nodulation of the successfully acclimatised plants was also observed. In short, multiple shoot buds were successfully induced, regenerated and rooted in vitro. The rooted plantlets were successfully acclimatised and grown healthily. It was concluded that a successful plant regeneration protocol of P. pinnata was achieved for potential application in micropropagation and genetic manipulation.

Alpha-glucosidase Inhibitory and Antioxidant Potential of Antidiabetic Herb Alternanthera sessilis: Comparative Analyses of Leaf and Callus Solvent Fractions.

BACKGROUND: Alternanthera sessilis is a medicinal herb which is consumed as vegetable and used as traditional remedies of various ailments in Asia and Africa. OBJECTIVE: This study aimed to investigate the antiglucosidase and antioxidant activity of solvent fractions of A. sessilis leaf and callus. MATERIALS AND METHODS: Leaf and callus methanol extracts were fractionated to produce hexane, chloroform, ethyl acetate, butanol, and water fractions. Antiglucosidase and 1,1-diphenyl-2-picrylhydrazyl scavenging activities as well as total phenolic (TP), total flavonoid (TF), and total coumarin (TC) contents were evaluated. Lineweaver-Burk plot analysis was performed on leaf and callus fractions with the strongest antiglucosidase activity. RESULTS: Leaf ethyl acetate fraction (LEF) had the strongest antiglucosidase (EC50 0.55 mg/mL) and radical scavenging (EC50 10.81 µg/mL) activity among leaf fractions. Callus ethyl acetate fraction (CEF) and chloroform fraction had the highest antiglucosidase (EC50 0.25 mg/mL) and radical scavenging (EC50 34.12 µg/mL) activity, respectively, among callus fractions. LEF and CEF were identified as noncompetitive and competitive α-glucosidase inhibitors, respectively. LEF and CEF had greater antiglucosidase activity than acarbose. Leaf fractions had higher phytochemical contents than callus fractions. LEF had the highest TP, TF, and TC contents. Antiglucosidase and antioxidant activities of leaf fractions correlated with phytochemical contents. CONCLUSION: LEF had potent antiglucosidase activity and concurrent antioxidant activity. CEF had the highest antiglucosidase activity among all fractions. Callus culture is a promising tool for enhancing production of potent α-glucosidase inhibitors. SUMMARY: Leaf ethyl acetate fraction (LEF) had the strongest antiglucosidase (EC50 0.55 mg/mL) and radical scavenging (EC50 10.81 µg/mL) activity among leaf fractionsCallus ethyl acetate fraction (CEF) and chloroform fraction had the highest antiglucosidase (EC50 0.25 mg/mL) and radical scavenging (EC50 34.12 µg/mL) activity, respectively, among callus fractionsLEF and CEF were identified as noncompetitive and competitive á-glucosidase inhibitors, respectivelyAntiglucosidase and antioxidant activities of leaf fractions correlated with phytochemical contents. Abbreviations used: LHF: Leaf hexane fraction, LCF: Leaf chloroform fraction, LEF: Leaf ethyl acetate fraction, LBF: Leaf butanol fraction, LWF: Leaf water fraction, CHF: Callus hexane fraction, CCF: Callus chloroform fraction, CEF: Callus ethyl acetate fraction, CBF: Callus butanol fraction, CWF: Callus water fraction, TP: Total phenolic, TF: Total flavonoid, TC: Total coumarin.