Study on antioxidant activity of certain plants in Thailand: Mechanism of antioxidant action of guava leaf extract

Abstract Background Herbal medicines are fast gaining popularity. However, their acceptability by modern practitioners is low which is often due to lack of standardization. Several approaches towards standardization of herbals have been employed. The current study attempted to recognize key peaks from 1H NMR spectra which together would comprise of a spectral fingerprint relating to efficacy of Psidium guajava (guava) leaf extract as an antidiarrhoeal when a number of unidentified active principles are involved. Methods Ninety samples of guava leaves were collected from three locations over three seasons. Hydroalcoholic (water and ethanol, 50:50) extracts of these samples were prepared and their 1H NMR spectra were acquired. Spectra were also obtained for quercetin, ferulic acid and gallic acid as standards. Eight bioassays reflecting different stages of diarrhoeal pathogenesis were undertaken and based on pre-decided cut-offs, the extracts were classified as ‘good’ or ‘poor’ extracts. The bioactivity data was then correlated with the 1H NMR profiles using Regression or Orthogonal Partial Least Square-Discriminant Analysis (OPLS-DA). Results OPLS-DA showed seasonal and regional segregation of extracts. Significant models were established for seven bioassays, namely those for anti-bacterial activity against Shigella flexneri and Vibrio cholerae, adherence of E. coli, invasion of E. coli and S. flexneri and production and binding of toxin produced by V. cholerae. It was observed that none of the extracts were good or bad across all the bioassays. The spectral analysis showed multiple peaks correlating with a particular activity. Based on NMR and LC-MS/MS, it was noted that the extracts contained quercetin, ferulic acid and gallic acid. However, they did not correlate with the peaks that segregated extracts with good and poor activity. Conclusions The current study identified key peaks in 1H NMR spectra contributing to the anti-diarrhoeal activity of guava leaf extracts. The approach of using spectral fingerprinting employed in the present study can thus be used as a prototype towards standardization of plant extracts with respect to efficacy.

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Red-fluorescent graphene quantum dots from guava leaf as a turn-off probe for sensing aqueous Hg(ii)

New Journal of Chemistry ◽

10.1039/d0nj06259f ◽

2021 ◽

Vol 45 (10) ◽

pp. 4617-4625

Author(s):

Rahul V. Khose ◽

Goutam Chakraborty ◽

Mahesh P. Bondarde ◽

Pravin H. Wadekar ◽

Alok K. Ray ◽

...

Keyword(s):

Quantum Dots ◽

Metal Ion ◽

Leaf Extract ◽

Graphene Quantum Dots ◽

Toxic Metal ◽

Guava Leaf

In this work, we have prepared red-fluorescent graphene quantum dots and utilized as a highly selective and sensitive fluorescence turn-off probe for detection of the toxic metal ion Hg2+ from guava leaf extract.

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X ray diffraction (XRD) analysis and evaluation of antioxidant activity of copper oxide nanoparticles synthesized from leaf extract of Cissus vitiginea

Materials Today Proceedings ◽

10.1016/j.matpr.2021.05.410 ◽

2021 ◽

Author(s):

Minakshi A. Thakar ◽

Subhesh Saurabh Jha ◽

Khongdet Phasinam ◽

Ravi Manne ◽

Yaser Qureshi ◽

...

Keyword(s):

Antioxidant Activity ◽

Copper Oxide ◽

Leaf Extract ◽

Xrd Analysis ◽

Copper Oxide Nanoparticles ◽

Oxide Nanoparticles ◽

X Ray Diffraction ◽

X Ray ◽

Analysis And Evaluation

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Characterization of Phytoconstituents from Alcoholic Extracts of Four Woody Species and Their Potential Uses for Management of Six Fusarium oxysporum Isolates Identified from Some Plant Hosts

Plants ◽

10.3390/plants10071325 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1325

Author(s):

Mohamed Z. M. Salem ◽

Abeer A. Mohamed ◽

Hayssam M. Ali ◽

Dunia A. Al Al Farraj

Keyword(s):

Antioxidant Activity ◽

Free Radical ◽

Benzoic Acid ◽

Fusarium Oxysporum ◽

Leaf Extract ◽

Antioxidant Activities ◽

Radical Scavenging ◽

Bark Extract ◽

Leaf Extracts ◽

Conium Maculatum

Background: Trees are good sources of bioactive compounds as antifungal and antioxidant activities. Methods: Management of six molecularly identified Fusarium oxysporum isolates (F. oxy 1, F. oxy 2, F. oxy 3, F. oxy 4, F. oxy 5 and F. oxy 6, under the accession numbers MW854648, MW854649, MW854650, MW854651, and MW854652, respectively) was assayed using four extracts from Conium maculatum leaves, Acacia saligna bark, Schinus terebinthifolius wood and Ficus eriobotryoides leaves. All the extracts were analyzed using HPLC-VWD for phenolic and flavonoid compounds and the antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and β-carotene-linoleic acid (BCB) bleaching assays. Results: In mg/kg extract, the highest amounts of polyphenolic compounds p-hydroxy benzoic, benzoic, gallic, and rosmarinic acids, with 444.37, 342.16, 311.32 and 117.87, respectively, were observed in C. maculatum leaf extract; gallic and benzoic acids with 2551.02, 1580.32, respectively, in A. saligna bark extract; quinol, naringenin, rutin, catechol, and benzoic acid with 2530.22, 1224.904, 798.29, 732.28, and 697.73, respectively, in S. terebinthifolius wood extract; and rutin, o-coumaric acid, p-hydroxy benzoic acid, resveratrol, and rosmarinic acid with 9168.03, 2016.93, 1009.20, 1156.99, and 574.907, respectively, in F. eriobotryoides leaf extract. At the extract concentration of 1250 mg/L, the antifungal activity against the growth of F. oxysporum strains showed that A. saligna bark followed by C. maculatum leaf extracts had the highest inhibition percentage of fungal growth (IPFG%) against F. oxy 1 with 80% and 79.5%, F. oxy 2 with 86.44% and 78.9%, F. oxy 3 with 86.4% and 84.2%, F. oxy 4 with 84.2, and 82.1%, F. oxy 5 with 88.4% and 86.9%, and F. oxy 6 with 88.9, and 87.1%, respectively. For the antioxidant activity, ethanolic extract from C. maculatum leaves showed the lowest concentration that inhibited 50% of DPPH free radical (3.4 μg/mL). Additionally, the same extract observed the lowest concentration (4.5 μg/mL) that inhibited BCB bleaching. Conclusions: Extracts from A. saligna bark and C. maculatum leaves are considered potential candidates against the growth of F. oxysporum isolates—a wilt pathogen—and C. maculatum leaf as a potent antioxidant agent.

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Supercritical Impregnation of PLA Filaments with Mango Leaf Extract to Manufacture Functionalized Biomedical Devices by 3D Printing

Polymers ◽

10.3390/polym13132125 ◽

2021 ◽

Vol 13 (13) ◽

pp. 2125

Author(s):

José María Rosales ◽

Cristina Cejudo ◽

Lidia Verano ◽

Lourdes Casas ◽

Casimiro Mantell ◽

...

Keyword(s):

Antioxidant Activity ◽

3D Printing ◽

Polylactic Acid ◽

Leaf Extract ◽

Three Dimensional ◽

3D Printer ◽

Pharmacological Properties ◽

Bioactive Properties ◽

Supercritical Impregnation ◽

Mango Leaves

Polylactic Acid (PLA) filaments impregnated with ethanolic mango leaves extract (MLE) with pharmacological properties were obtained by supercritical impregnation. The effects of pressure, temperature and amount of extract on the response variables, i.e., swelling, extract loading and bioactivity of the PLA filaments, were determined. The analysis of the filaments biocapacities revealed that impregnated PLA filaments showed 11.07% antidenaturant capacity and 88.13% antioxidant activity, which after a 9-day incubation shifted to 30.10% and 9.90%, respectively. Subsequently, the same tests were conducted on printed samples. Before their incubation, the printed samples showed 79.09% antioxidant activity and no antidenaturant capacity was detected. However, after their incubation, the antioxidant activity went down to only 2.50%, while the antidenaturant capacity raised up to 23.50%. The persistence of the bioactive properties after printing opens the possibility of using the functionalized PLA filaments as the feed for a three-dimensional (3D) printer.

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