Comparison of antioxidative properties of carbazole alkaloids from Murraya koenigii leaves

A new dimeric carbazole alkaloid, 8,10′-[3,3′,11,11′ -tetrahydro-9,9′-dihydroxy-3,3′,5,8′-tetramethyl-3, 3′-bis(4-methyl-3-pentenyl)]bipyrano[3,2-a]carbazole (12), was isolated from the CH2Cl2 extract of Murraya koenigii together with six known carbazole alkaloids, koenimbine (6), O-methylmurrayamine A (7), O-methylmahanine (8), isomahanine (9), bismahanine (10), and bispyrayafoline (11). Their structures were determined on the basis of 1H and 13C NMR spectroscopic and mass spectrometric (MS) data. The antioxidative properties of 12 carbazole alkaloids isolated from leaves of M. koenigii were evaluated on the basis of the oil stability index together with their radical scavenging ability against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. On the basis of the lag time to reach a steady state, the 12 carbazoles were classified into three groups. It is suggested that an aryl hydroxyl substituent on the carbazole rings plays a role in stabilizing the thermal oxidation and rate of reaction against DPPH radical

Antioxidative activity of carbazoles from Murraya koenigii leaves

The antioxidative properties of the leaves extracts of Murraya koenigii using different solvents were evaluated based on the oil stability index (OSI) together with their radical scavenging ability against 1-1-diphenyl-2-picrylhydrazyl (DPPH). The methylene chloride (CH2Cl2) extract and the ethyl acetate (EtOAc) soluble fraction of the 70% acetone extract significantly prolonged the OSI values comparable to those of α-tocopherol and BHT. Five carbazole alkaloids were isolated from the CH2Cl2 extract and their structures were identified to be euchrestine B (1), bismurrayafoline E (2), mahanine (3), mahanimbicine (4), and mahanimbine (5) based on 1H and 13C NMR and mass (MS) spectral data. The OSI value of carbazoles at 110 °C decreased in the order 1 and 3 > α-tocopherol > BHT > 2 > 4, 5 and control. It is assumed that compounds 1 and 3 contributed to the high OSI value of the CH2Cl2 extract of M. koenigii. The DPPH radical scavenging activity for these carbazoles was in the order ascorbic acid > 2 > 1, 3 and α-tocopherol > BHT > 4 and 5

The antioxidative components from Alpinia nutans

The methylene chloride extract of Alpinia nutans was investigated for its antioxidant constituents. 5,6-Dehydrokawain (1), flavokawin-B (2), 1,7-diphenyl-5-hydroxy-6-hepten-3-one (3), (-)-pinocembrin (4) and a mixture of stigmasterol and β-sitosterol were isolated. The antioxidant activity was measured on isolates 1-4 using ferric thiocyanate (FTC) and diphenylpicrylhydrazyl (DPPH) free radical scavenging techniques

Phytochemical Screening and Polyphenolic Antioxidant Activity of Aqueous Crude Leaf Extract of Helichrysum pedunculatum

We evaluated the in vitro antioxidant property and phytochemical constituents of the aqueous crude leaf extract of Helichrysum pedunculatum. The scavenging activity on superoxide anions, DPPH, H2O2, NO and ABTS; and the reducing power were determined, as well as the flavonoid, proanthocyanidin and phenolic contents of the extract. The extract exhibited scavenging activity towards all radicals tested due to the presence of relatively high total phenol and flavonoids contents. Our findings suggest that H. pedunculatum is endowed with antioxidant phytochemicals and could serve as a base for future drugs

The interplay of descriptor-based computational analysis with pharmacophore modeling builds the basis for a novel classification scheme for feruloyl esterases

One of the most intriguing groups of enzymes, the feruloyl esterases (FAEs), is ubiquitous in both simple and complex organisms. FAEs have gained importance in biofuel, medicine and food industries due to their capability of acting on a large range of substrates for cleaving ester bonds and synthesizing high-added value molecules through esterification and transesterification reactions. During the past two decades extensive studies have been carried out on the production and partial characterization of FAEs from fungi, while much less is known about FAEs of bacterial or plant origin. Initial classification studies on FAEs were restricted on sequence similarity and substrate specificity on just four model substrates and considered only a handful of FAEs belonging to the fungal kingdom. This study centers on the descriptor-based classification and structural analysis of experimentally verified and putative FAEs; nevertheless, the framework presented here is applicable to every poorly characterized enzyme family. 365 FAE-related sequences of fungal, bacterial and plantae origin were collected and they were clustered using Self Organizing Maps followed by k-means clustering into distinct groups based on amino acid composition and physico-chemical composition descriptors derived from the respective amino acid sequence. A Support Vector Machine model was subsequently constructed for the classification of new FAEs into the pre-assigned clusters. The model successfully recognized 98.2% of the training sequences and all the sequences of the blind test. The underlying functionality of the 12 proposed FAE families was validated against a combination of prediction tools and published experimental data. Another important aspect of the present work involves the development of pharmacophore models for the new FAE families, for which sufficient information on known substrates existed. Knowing the pharmacophoric features of a small molecule that are essential for binding to the members of a certain family opens a window of opportunities for tailored applications of FAEs

Preliminary phytochemical screening and In vitro antioxidant activities of the aqueous extract of Helichrysum longifolium DC

<p>Abstract</p> <p>Background</p> <p>Many oxidative stress related diseases are as a result of accumulation of free radicals in the body. A lot of researches are going on worldwide directed towards finding natural antioxidants of plants origins. The aims of this study were to evaluate <it>in vitro </it>antioxidant activities and to screen for phytochemical constituents of <it>Helichrysum longifolium </it>DC. [Family Asteraceae] aqueous crude extract.</p> <p>Methods</p> <p>We assessed the antioxidant potential and phytochemical constituents of crude aqueous extract of <it>Helichrysum longifolium </it>using tests involving inhibition of superoxide anions, DPPH, H₂O₂, NO and ABTS. The flavonoid, proanthocyanidin and phenolic contents of the extract were also determined using standard phytochemical reaction methods.</p> <p>Results</p> <p>Phytochemical analyses revealed the presence of tannins, flavonoids, steroids and saponins. The total phenolic content of the aqueous leaf extract was 0.499 mg gallic acid equivalent/g of extract powder. The total flavonoid and proanthocyanidin contents of the plant were 0.705 and 0.005 mg gallic acid equivalent/g of extract powder respectively. The percentage inhibition of lipid peroxide at the initial stage of oxidation showed antioxidant activity of 87% compared to those of BHT (84.6%) and gallic acid (96%). Also, the percentage inhibition of malondialdehyde by the extract showed percentage inhibition of 78% comparable to those of BHT (72.24%) and Gallic (94.82%).</p> <p>Conclusions</p> <p>Our findings provide evidence that the crude aqueous extract of <it>H. longifolium </it>is a potential source of natural antioxidants, and this justified its uses in folkloric medicines.</p

Screening of Zingiberaceae extracts for antimicrobial and antioxidant activities

Dichloromethane and methanol extracts of 13 Zingiberaceae species from the Alpinia, Costus and Zingiber genera were screened for antimicrobial and antioxidant activities. The antimicrobial activity of most of the extracts was antibacterial with only the methanol extract of Costus discolor showing very potent antifungal activity against only Aspergillus ochraceous (MID, 15.6 μg per disc). All the extracts showed strong antioxidant activity comparable with or higher that of α-tocopherol

Antioxidant and antitumor promoting activities of the flavonoids from Hedychium thyrsiforme

Five flavonoids, including 3,7,4′-trimethoxy-5-hydroxyflavone (1), 3,4′-dimethoxy-5,7-dihydroxyflavone (2), 5,7,4′-trimethoxy-3-hydroxyflavone (3), 3,5,7,4′-tetramethoxyflavone (4), and 7,4′-dimethoxy-3,5-dihydroxyflavone (5), were isolated from the rhizome of Hedychium thyrsiforme and assayed for antioxidant and antitumor promoting activities. The antioxidant assays showed that 5,7,4′-trimethoxy-3-hydroxyflavone, 7,4′-dimethoxy-3,5-dihydroxyflavone and 3,4′-dimethoxy-5,7-dihydroxyflavone had strong activities. Only two compounds, 5,7,4′-trimethoxy-3-hychoxyflavone and 7,4′-dimethoxy-3,5-dihydroxyflavone, were found to be strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavengers with fifty percent inhibition concentration (IC50) values of 92 and 119 μM, respectively. Antitumor promoting assays indicated that all the flavonoids showed strong inhibition activity towards Epstein-Barr virus (EBV) activation in Raji cells