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Isolation and identification of radical scavenging and tyrosinase inhibition of polyphenols from Tibouchina semidecandra L

Sirat HM, Rezali MF, Ujang Z

J Agric Food Chem, 2010 Oct 13;58(19):10404-9.
PMID: 20809630 DOI: 10.1021/jf102231h

Phytochemical and bioactivity studies of the leaves and stem barks of Tibouchina semidecandra L. have been carried out. The ethyl acetate extract of the leaves yielded four flavonoid compounds, identified as quercetin, quercetin 3-O-α-l-(2''-O-acetyl) arabinofuranoside, avicularin, and quercitrin, while the stem barks gave one ellagitannin, identified as 3,3'-O-dimethyl ellagic acid 4-O-α-l-rhamnopyranoside. Evaluation of the antioxidative activity on the crude extracts and pure compounds by electron spin resonance (ESR) and ultraviolet-visible (UV-vis) spectrophotometric assays showed that the pure isolated polyphenols and the EtOAc extract possessed strong antioxidative capabilities. Quercetin was found to be the most active radical scavenger in DPPH-UV and ESR methods with SC(50) values of 0.7 μM ± 1.4 and 0.7 μM ± 0.6 μM, respectively, in the antioxidant assay. A combination of quercetin and quercitrin was tested for synergistic antioxidative capacity;, however, there was no significant improvement observed. Quercetin also exhibited strong antityrosinase activity with a percent inhibition of 95.0% equivalent to the positive control, kojic acid, in the tyrosinase inhibition assay.
Friedelin and lanosterol from Garcinia prainiana stimulated glucose uptake and adipocytes differentiation in 3T3-L1 adipocytes

Susanti D, Amiroudine MZ, Rezali MF, Taher M

Nat Prod Res, 2013 Mar;27(4-5):417-24.
PMID: 22988818 DOI: 10.1080/14786419.2012.725399

Friedelin and lanosterol have been isolated from twigs of Garcinia prainiana. Their structures were elucidated by spectroscopic methods. The compounds were examined for their effects on 3T3-L1 adipocytes. In the MTT assay, it was found that the compounds had no cytotoxic effects up to 25 µM. Adipocyte differentiation analysis was carried out by Oil Red O staining method. In the presence of adipogenic cocktail (MDI), it was found that friedelin and lanosterol enhanced intracellular fat accumulation by 2.02 and 2.18-fold, respectively, compared with the vehicle-treated cells. Deoxyglucose uptake assay was used to examine the insulin sensitivity of adipocytes in the presence of the compounds. It was found that friedelin was able to stimulate glucose uptake up to 1.8-fold compared with insulin-treated cells. It was suggested that friedelin and lanosterol may be beneficial to mimic insulin action that would be useful in the treatment of diabetes type 2 patients.
Haplophytin B from Maclurodendron porteri

Taher M, Susanti D, Abd Hamid S, Edueng K, Jaffri JM, Adina AB, et al.

Pak J Pharm Sci, 2014 Jan;27(1):179-81.
PMID: 24374446

An alkaloid from Maclurodendron porteri has been isolated and characterized. Extraction process was conducted by acid-base extraction method followed by column chromatography. The structure was established by nuclear magnetic resonance spectroscopy and mass spectrometry. The compound was identified as haplophytin B which occurs commonly in the Rutaceae family. However, this is the first time this alkaloid was isolated and reported from the species. The compound showed no inhibition against Staphylococus aureus, Pseudomonas aeruginosa, Bacillus cereus and Escherichia coli and no cytotoxic activity against H199 and A549 cell lines.
Production and characterization of violacein by locally isolated Chromobacterium violaceum grown in agricultural wastes

Ahmad WA, Yusof NZ, Nordin N, Zakaria ZA, Rezali MF

Appl Biochem Biotechnol, 2012 Jul;167(5):1220-34.
PMID: 22278051 DOI: 10.1007/s12010-012-9553-7

The present work highlighted the production of violacein by the locally isolated Chromobacterium violaceum (GenBank accession no. HM132057) in various agricultural waste materials (sugarcane bagasse, solid pineapple waste, molasses, brown sugar), as an alternative to the conventional rich medium. The highest yield for pigment production (0.82 g L⁻¹) was obtained using free cells when grown in 3 g of sugarcane bagasse supplemented with 10% (v/v) of L-tryptophan. A much lower yield (0.15 g L⁻¹) was obtained when the cells were grown either in rich medium (nutrient broth) or immobilized onto sugarcane bagasse. Violacein showed similar chemical properties as other natural pigments based on the UV-Vis, Fourier transform infrared spectroscopy, thin-layer chromatography, nuclear magnetic resonance, and mass spectrometry analysis. The pigment is highly soluble in acetone and methanol, insoluble in water or non-polar organic solvents, and showed good stability between pH 5-9, 25-100 °C, in the presence of light metal ions and oxidant such as H₂O₂. However, violacein would be slowly degraded upon exposure to light. This is the first report on the use of cheap and easily available agricultural wastes as growth medium for violacein-producing C. violaceum.
Fulltext Apoptosis, antimicrobial and antioxidant activities of phytochemicals from Garcinia malaccensis Hk.f

Taher M, Susanti D, Rezali MF, Zohri FS, Ichwan SJ, Alkhamaiseh SI, et al.

Asian Pac J Trop Med, 2012 Feb;5(2):136-41.
PMID: 22221758 DOI: 10.1016/S1995-7645(12)60012-1

OBJECTIVE: To study the chemical constituents of stembark of Garcinia malaccensis (G. malaccensis) together with apoptotic, antimicrobial and antioxidant activities.
METHODS: Purification and structure elucidation were carried out by chromatographic and spectroscopic techniques, respectively. MTT and trypan blue exclusion methods were performed to study the cytotoxic activity. Antibacterial activity was conducted by disc diffusion and microdilution methods, whereas antioxidant activities were done by ferric thiocyanate method and DPPH radical scavenging.
RESULTS: The phytochemical study led to the isolation of α,β-mangostin and cycloart-24-en-3β-ol. α-Mangostin exhibited cytotoxic activity against HSC-3 cells with an IC(50) of 0.33 μM. β- and α-mangostin showed activity against K562 cells with IC(50) of 0.40 μM and 0.48 μM, respectively. α-Mangostin was active against Gram-positive bacteria, Staphylococcus aureus (S. aureus) and Bacillus anthracis (B. anthracis) with inhibition zone and MIC value of (19 mm; 0.025 mg/mL) and (20 mm; 0.013 mg/mL), respectively. In antioxidant assay, α-mangostin exhibited activity as an inhibitor of lipid peroxidation.
CONCLUSIONS: G. malaccensis presence α- and β-mangostin and cycloart-24-en-3β-ol. β-Mangostin was found very active against HSC-3 cells and K562. The results suggest that mangostins derivatives have the potential to inhibit the growth of cancer cells by inducing apoptosis. In addition, α-and β-mangostin was found inhibit the growth of Gram-positive pathogenic bacteria and also showed the activity as an inhibitor of lipid peroxidation.
A new xanthone dimer and cytotoxicity from the stem bark of Calophyllum canum

Taher M, Salleh WMNHW, Alkhamaiseh SI, Ahmad F, Rezali MF, Susanti D, et al.

Z Naturforsch C J Biosci, 2021 Jan 27;76(1-2):87-91.
PMID: 32931451 DOI: 10.1515/znc-2020-0089

A phytochemical investigation of the stem bark of Calophyllum canum resulted in the isolation of a new xanthone dimer identified as biscaloxanthone (1), together with four compounds; trapezifoliaxanthone (2), trapezifolixanthone A (3), taraxerone (4) and taraxerol (5). The structures of these compounds were determined via spectroscopic methods of IR, UV, MS and NMR (1D and 2D). The cytotoxicity of compounds 1-3 were screened against A549, MCF-7, C33A and 3T3L1 cell lines, wherein weak cytotoxic activities were observed (IC50 > 50 μm).
A lignan with glucose uptake activity in 3T3-L1 adipocytes from the stem bark of Knema patentinervia

Taher M, Amiroudine MZAM, Jaffri JM, Amri MS, Susanti D, Abd Hamid S, et al.

Pak J Pharm Sci, 2017 Jul;30(4):1335-1339.
PMID: 29039334

A new naturally occurring dibenzylbutyrolactone lignan named isocubebinic ether has been isolated from Knema patentinervia. The structure was established by spectroscopic methods, which include Ultraviolet, Infrared, Nuclear Magnetic Resonance and Mass Spectrometry. The compound showed activity in the stimulation of glucose uptake by 3T3-L1 adipocytes.