Farediah Ahmad

Chemical compositions, antioxidant and antimicrobial activities of essential oils of Piper caninum Blume.

Chemical composition, antioxidant and antimicrobial activities of the fresh leaves and stems oils of Piper caninum were investigated. A total of forty eight constituents were identified in the leaves (77.9%) and stems (87.0%) oil which were characterized by high proportions of phenylpropanoid, safrole with 17.1% for leaves and 25.5% for stems oil. Antioxidant activities were evaluated by using β-carotene/linoleic acid bleaching, DPPH radical scavenging and total phenolic content. Stems oil showed the highest inhibitory activity towards lipid peroxidation (114.9 ± 0.9%), compared to BHT (95.5 ± 0.5%), while leaves oil showed significant total phenolic content (27.4 ± 0.5 mg GA/g) equivalent to gallic acid. However, the essential oils showed weak activity towards DPPH free-radical scavenging. Evaluation of antimicrobial activity revealed that both oils exhibited strong activity against all bacteria strains with MIC values in the range 62.5 to 250 μg/mL, but weak activity against fungal strains. These findings suggest that the essential oils can be used as antioxidant and antimicrobial agents for therapeutic, nutraceutical industries and food manufactures.

Apoptosis, antimicrobial and antioxidant activities of phytochemicals from Garcinia malaccensis Hk.f

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.

The Mechanisms of Inhibition of Advanced Glycation End Products Formation through Polyphenols in Hyperglycemic Condition.

Glycation, the non-enzymatic binding of glucose to free amino groups of an amino acid, yields irreversible heterogeneous compounds known as advanced glycation end products. Those products play a significant role in diabetic complications. In the present article we briefly discuss the contribution of advanced glycation end products to the pathogenesis of diabetic complications, such as atherosclerosis, diabetic retinopathy, nephropathy, neuropathy, and wound healing. Then we mention the various mechanisms by which polyphenols inhibit the formation of advanced glycation end products. Finally, recent supporting documents are presented to clarify the inhibitory effects of polyphenols on the formation of advanced glycation end products. Phytochemicals apply several antiglycation mechanisms, including glucose metabolism, amelioration of oxidative stress, scavenging of dicarbonyl species, and up/down-regulation of gene expression. To utilize polyphenols in order to remedy diabetic complications, we must explore, examine and clarify the action mechanisms of the components of polyphenols.

Isobutylamides from Piper ridleyi

Abstract Extraction of the stems and leaves of Piper ridleyi with ether afforded N - iso butyl-15-(3′,4′-methylenedioxyphenyl)-2 E ,4 E ,12 E -pentadecatrienamide (ridleyamide), as well as the known amide, retrofractamide, and sterols.

Chemical composition and biological activities of essential oil of Beilschmiedia pulverulenta

Abstract Context: The ethnopharmacological study of Beilschmiedia indicates that several species are used for the treatment of various ailments. Objective: This is the first study of the chemical composition of Beilschmiedia pulverulenta Kosterm (Lauraceae) essential oil and its antioxidant, antimicrobial, antityrosinase, anti-inflammatory, and anticholinesterase activities. Materials and methods: The antioxidant activities were evaluated by β-carotene, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric-reducing antioxidant power (FRAP), and phenolic content at different concentrations. The antimicrobial activities against Gram-positive and Gram-negative bacteria and fungi were revealed by disk diffusion and microdilution. The antityrosinase and anti-inflammatory activities were assayed against mushroom tyrosinase and lipoxygenase enzymes. The anticholinesterase activity was analyzed using acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. Results: Forty-two components were detected in B. pulverulenta oil with eugenol (45.3%) being the major component. The oil phenolic content and the FRAP were 660.1 mg gallic acid/g and 604.0 mg ascorbic acid/g, respectively. The oil gave an IC50 value of 94.5 µg/mL and an inhibition of 93.9% in DPPH and β-carotene, respectively. The antimicrobial activity showed that the oil had strong activity against all Gram-positive bacteria with an minimum inhibitory concentration (MIC) value each of 62.5 µg/mL and moderate against all fungi with MIC and minimum bactericidal concentration (MBC) values each of 125 µg/mL. The oil showed significant antityrosinase and anti-inflammatory activities with 67.6 and 62.5% inhibition, respectively. In addition, the oil had moderate AChE (56.5%) and BChE (48.2%) activities. Discussion and conclusion: The results show that the oil could potentially be used for nutraceutical industries, food manufactures, and therapeutic agents against various diseases such as inflammation and rheumatism.

Fabrication of a composite modified glassy carbon electrode: a highly selective, sensitive and rapid electrochemical sensor for silver ion detection in river water samples

In this study, a glassy carbon electrode (GCE) was modified with multi-walled carbon nanotubes (MWCNTs), 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6), N,N′-bis(2-hydroxyacetophenone)ethylenediamine (BZE) and Nafion to form a MWCNT-BZE-[bmim]PF6-Nafion-GCE. The electrochemical behaviour of the modified electrode with respect to silver (Ag(I)) ion detection was studied by cyclic voltammetry (CV) and differential pulse anodic stripping voltammetry (DPASV). Furthermore, the experimental parameters including the pH value of Britton–Robinson Buffer (BRB), Nafion, MWCNTs, BZE and ([bmim]PF6) concentrations and the deposition potential and time were optimized. The detection limit of the modified electrode for the Ag(I) ion was found to be 70 ng L−1 (6.49 × 10−10 mol L−1). Repetitive measurements revealed good reproducibility with a relative standard deviation (RSD) value of 0.4%. The system performance of the modified electrode was highly satisfactory and the recoveries for river water samples were found to be 96–121%. This study proved that the MWCNT-BZE-[bmim]PF6-Nafion-GCE is a highly selective and sensitive modified electrode for the detection of the Ag(I) ion in river water samples with good recovery value.

Chemical constituents from tiger's betel, Piper porphyrophyllum N.E.Br. (Fam. Piperaceae).

Seven flavonoid compounds have been isolated from the aerial parts of tigers betel (Piper porphyrophyllum), which were identified as 5,7-dimethoxyflavone, 4′,5,7-trimethoxy-flavone, 3′,4′,5,7-tetramethoxyflavone, 4′-hydroxy-3′,5,7-trimethoxyflavone, 5-hydroxy-3′,4′,7-trimethoxyflavone, 4′,5-dihydroxy-3′,7-dimethoxyflavone and 5-hydroxy-7-methoxyflavanone. The identification of all compounds was achieved by physical properties and spectroscopically. These data were also confirmed by comparison with previously reported spectral data. Flavonoid compounds with high content in P. porphyrophyllum can probably be used as a chemical marker for this Piper species.

Cytotoxic and Antibacterial Evaluation of Coumarins and Chromanone Acid from Calophyllum symingtonianum

Calophyllum symingtonianum is a rare species from the Calophyllum genus that belongs to the Guttiferae family. Calophyllum has been recognized as a potential medicinal plant due to its many bioactive phytochemicals especially coumarins and chromanone acids. In this study, the cytotoxic activities against MCF-7 and A-549 and antibacterial activities towards S. aureus, B. subtilis, P. aeruginosa and E. Coli of three coumarins known as inophyllum D, inophyllum H and calanone as well as chromanone acid identified as isocordato-oblongic acid isolated from this plant were evaluated. Inophyllum H exhibited the highest IC50 values against MCF-7 at 25.56 μg/mL and A-549 at 26.41μg/mL. Isocordato-oblongic acid showed moderate antibacterial activity against S. aureus and B. subtilis at 125μg/mL and 62.5μg/mL, respectively. This study suggests C. symingtonianum as a potential plant for cytotoxic and antibacterial phytochemicals.

Essential oil compositions of Malaysian lauraceae: A mini review

Essential oils have been largely employed for human need due to their antibacterial, antifungal and insecticidal activities. At present, approximately 3000 essential oils are known, 300 of which are commercially important. Essential oils or some of their components are used in perfumes and make-up products, sanitary products, dentistry, agriculture, as food preservers and additives, and as natural remedies. The essential oil compositions of Malaysian Lauraceae family have been investigated for many years. In the recent years, studies on the essential oils of the species have been progressing and many of them have reported interesting pharmacological activities. In this article, we summarized and updated the chemical compositions and biological activities of Malaysian Lauraceae. Throughout our literature review, only four genera which are Lindera, Beilschmiedia, Litsea, and Cinnamomum have been studied for their essential oil compositions in Malaysia. They were found to contain mainly safrole, eugenol, linalool, camphor, benzyl benzoate or cinnamaldehyde as major components. There were significant priorities to find out the details of the chemical compositions of the essential oils from Malaysian Lauraceae. Therefore, more clinical studies on the toxicity of the essential oil of the species are also crucial to ensure their safety and to assess their eligibility to be used as the sources of modern medicines.

Antioxidant and tyrosinase inhibition activities of α- mangostin and Garcinia mangostana Linn. pericarp extracts

The methanol, ethyl acetate and petroleum ether crude extracts of mangosteen pericarp and α- mangostin were evaluated for the antioxidant capacity and tyrosinase inhibition properties. The ferric reducing antioxidant power (FRAP) assay was used to investigate their antioxidant capacity. Tyrosinase inhibition effect was evaluated using mushroom tyrosinase inhibition assay. Methanol extract has higher antioxidant reducing capacity (m= 1.621), compared to the rest of the extracts. Meanwhile, ethyl acetate extract and α- mangostin showed potent tyrosinase inhibition activities as compared to Kojic acid, a well- known tyrosinase inhibitor. It is observed that tyrosinase inhibition effect is antioxidant independent as ethyl acetate extract possessed low antioxidant capacity. This study suggests direct tyrosinase inhibition by ethyl acetate extract of Garcinia mangostana.