[en] Garcinia mangostana Linn,(Family; Guttiferae) is known to be a rich source of bioactive molecules including flavonoids, benzophenones and lactones. A variety of xanthones have been isolated from mangosteen plants and fruits include the hull, rind heartwood and flesh. The fruit hull is used as an astringent and also used against cholera, dysentery and diarrhoea in traditional medicinal system. Petroleum ether extraction of the dried and powered fruit hulls followed by column chromatographic separation afforded two compounds, namely, gartanin (1) (0.48% in yield, mp 146-152 ) and mangostin (2) (0.97% in yield, mp (179-180). The structures of these two compounds have been identified by UV, FT-IR, NMR and EIMS. These identifications were confirmed by comparison of melting point values with reported data in the literature

[en] In the present study, twenty four commercial tea samples were assayed to determine their free radical scavenging activity and polyphenolic contents based on the brewing/infusing period. Tea samples were infused/brewed in 200 mL boiled water at 120 degree C for 1, 2 and 5 min, respectively. The radical scavenging activities of tea infusion/brewing were measured using 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) assay method. The results were ranged from 67.81-90.51% for black tea bags, 90.37-94.51% for green tea bags, 24.66-92.25% for black tea powder, 16.08-93.06% for green tea powder and 32.90- 45.54% for Camomile herbal infusion. The results showed that 1 or 2 min black tea bags infusion exhibited highest radical scavenging activity than 5 min infusion. Antioxidant activities of tea powders were variable with the amount of tea powder. It was observed that antioxidant activity increased with increasing boiling time for smaller amount of sample. In contrary, shorter boiling time was better for larger amount of sample. The polyphenol contents of tea infusion were determined and the results were expressed as milligram quercetin equivalent/200 mL of tea infusion. The polyphenol content was increased with increased brewing period. In contrary, brewing for longer time rendered extract less antiradical activity. This study suggests that infusing tea bag for 1 or 2 min is sufficient for getting infusion with maximum radical scavenging activity and in case of tea powder, shorter boiling time is better for larger amount of powder or small amount of powder should be boiled for minimum 5 min for rendering extract with maximum radical scavenging activity. (author)

[en] Flavonoids are specialized compounds widely distributed throughout the plant kingdom with diverse functions in plants and benefits for human health. In particular, flavonols, synthesized by flavonol synthase (FLS), protect plants against UV-B radiation and are essential for male fertility in maize. We have recently characterized a UV-B inducible ZmFLS1 which was the first enzyme to be described in monocot plants. Interestingly, the new assembly of the B73 genome revealed the presence of a second putative FLS gene (ZmFLS2) with extremely high similarity both at the nucleotide and amino acid level. Expression analysis showed that both genes are UV-B regulated in inbred lines and high altitude landraces. By combining EMSA assays and transient expression experiments, we were able to show that both genes are direct targets of the transcription factors P1, C1 and R involved in flavonoid biosynthesis regulation. Moreover, the high sequence conservation of the ZmFLS promoters between maize lines would indicate that the differences observed in ZmFLS expression could be explained by allelic variations in the transcription factor activities. Finally, the presence of two FLS genes in maize and sorghum, and one in rice and Brachypodium, in addition to the evolutionary distances across the grasses suggest that duplication of the FLS gene occurred early in evolution. (authors)

[en] Interactions of four structurally related flavonoids - quercetin, rutin, morin and catechin with peroxyl radicals using liposome/N-tert-butyl-alpha-phenylnitrone (PBN) and liposome -(4-pyridyl-N-oxide)-N-tert-butylnitrone (POBN)-spin trap systems have been studied through spin trapping ESR. Results obtained were different from that of conjugated diene analysis experiments, where lag phases indicated radical scavenging activity of all the flavonoids. No clear lag phase was observed in ESR experiments under same conditions. In the presence of flavonoids decreasing ESR signals of spin adducts in PBN, while no or negligibly smaller spin adducts with POBN system were observed which may be attributed to the possibility that spin traps interacted with free radicals. Experiments with buffer/spin trap systems without liposome revealed that spin adducts were only stable with catechin and destroyed by quercetin, rutin and morin in buffer/spin trap systems. These results further assured that quercetin, rutin and morin not only interacted with peroxyl radicals but also with spin adducts. (author)

[en] The present studies comprise the distribution of important flavonoids amongst the selected 13 medicinal plants viz., Woodfordia fruticosa, Adhatoda vasica, Chenopodium ambrosoides, Viburnum cotinifolium, Euphorbia hirta, Vitex negundo, Peganum harmala, Broussonetia papyrifera, Taraxacum officinale, Urtica dioica, Verbascum thapsus, Caryopteris grata and Mimosa rubicaulis collected from Margalla Hills for their authentication. Kaemferol was only detected in Verbascum thapsus. Myrcetin was detected in Woodfordia fruticosa, Viburnum cotinifolium, Euphorbia hirta, Vitex negundo and Broussonetia papyrifera. Catechin was detected in Woodfordia fruticosa , Chenopodium ambrosoides and Caryopteris grata. Vitexin was found absent in all the plants under study except Adhatoda vasica, Chenopodium ambrosoides and Peganum harmala. Orientin was detected in Woodfordia fruticosa, Adhatoda vasica, Viburnum cotinifolium, Euphorbia hirta, Vitex negundo, Peganum harmala, Urtica dioica and Caryopteris grata. Rutin and Kaempferol-7-neohesperoside were detected only in Broussonetia papyrifera. Quercitin was detected in Euphorbia hirta, Verbascum thapsus, Caryopteris grata and Mimosa rubicaulis. Luteolin was common among all the species. (author)

[en] Grape canes are the main agro-wastes from vineyards. This work studied the antioxidant activities of the defatted methanolic extracts (ME) of canes from 11 genotypes: 5 Vitis vinifera widely known cultivars and 6 Chinese wild varieties from three species (V. amurensis, V. davidii, and V. pentagona) and the antioxidant activities of the ME’s chloroform fractions (CF), ethyl acetate fractions (EAF) and water fractions (WF). Among ME and its three fractions, EAF’s total phenolic contents (TPC) and total flavonoid contents (TFC) were the highest, at 586 mg/g of gallic acid equivalent and 320 mg/g of quercetin equivalent, respectively. The antioxidant power of the fractions/extracts was in the order EAF > ME > WF > CF, based on the DPPH radical-scavenging power and ferric-reducing antioxidant activity, while the order was EAF > CF > WF >ME based on the β-carotene-linoleic acid bleaching activity. Methanolic extracts demonstrated the strongest Fe2+-chelating activity. The antioxidant activities of the extracts/fractions generally correlated with the TPC and TFC in all assays, except with the Fe2+-chelating test. Grape canes from V. davidii had the highest TPC, TFC and antioxidant activities compared with those from other grape species. Catechin, epicatechin and trans-resveratrol were the predominant phenolic components of fractions/extracts. In light of these valuable bioactivities, grape canes from annual pruning practice considered as waste material have good commercial potential for utilization as a promising natural antioxidant in the food, pharmaceutical and cosmetic industries, given its low cost and availability in large amounts. (Author)

[en] This doctoral thesis studies the following topics: medical chemistry, organic chemistry, flavonoids, cancer chemo prevention

[en] Fourteen compounds (1-14) namely 3-carbomethoxyindole (1), 6-hydroxy-7-methoxycoumarin (2), methyl-4-hydroxybenzoate (3), 4-hydroxybenzoic acid (4), p-coumaric acid (5), oleanolic acid (6), 4-ketopinoresinol (7), apigenin (8), apigenin-7-p-coumerate (9) apigenin-7-O-beta-D-glucopyranoside (10), acacetin-7-O-(4-hydroxy-E-cinnamoyl-(6)-beta-D-glucopyranoside (11), apigenin-7-O-(4-hydroxy-E-cinnamoyl-(6)-beta-D-glucopyranoside (12), -bis(4-hydroxy-E-cinnamoyl))glucopyranoside 6 apigenin 7-O-beta-D-(2 (13) and apigenin 7-O-rutinoside (14) were isolated from the methanolic extract of the whole plant of Chrozophora plicata. The structures of these compounds were confirmed by UV, IR, NMR (1H and 13C) spectroscopy and mass spectrometry (EIMS, HREIMS, FABMS, HRFABMS) and in comparison with reported data in literature. These isolates (1-14) showed DPPH radical scavenging and enzyme inhibitory activities against enzyme acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and lipoxygenase (LOX). (author)

[en] In continuation of our search for bioactive secondary metabolites from Seriphidium stenocephalum, chromatographic analysis of some ignored fractions from previous work on ethyl acetate part of the methanolic extract yielded five new sphingolipids; seriphidalin A ((2S,3S,4R,12E)-2-((heptdecanoyl)amino)unieicos-12-ene-1,3,4-triol; 1), seriphidalin B ((2S,3S,4R,12E)-2-(((2R)-2-hydroxydodidecanoyl)amino)trididec-12-ene-1,3, 4-triol; 2), seriphidalin C ((2S,3S,4R,9E)-2-(((2R)-2-hydroxydodidecanoyl)amino)didec-9-ene-1,3,4-triol 3), seriphidalin D ((2S,3S,4R)-2-(((2R,5E)-2-hydroxyheptadec-5-enoyl)amino) pentadecane-1,3,4-triol-1-O-beta-D-galactopyranoside; 4) and seriphidalin E ((2S,3S,4R,7E,12E)-2-(((2R)-2-hydroxyheptanoyl)amino)heptadeca-7,12-diene-1 3,4-triol-1-O-beta-D-glucopyranoside; 5) together with five known compounds (6-10). The structures of the isolated compounds were determined by 1D and 2D NMR and high resolution mass spectrometry. (author)

[en] Chromatographic purification of the methanolic extract of Tecomella undulata yielded a new flavonoid glycoside; di-p-E-coumaroyl-alpha-L-rhamnosyl(16)) ,4 kaempferol-3-O-beta-D-(3 galactoside (1), two new megastigmanes; (6R 7Z)-9,10-dihydroxy-4,7-megastigmadien-3-one (2) and (6E)-9,10-dihydroxy-4,6-megastigmadien-3-one (3) along with three known compounds; (6R 9S)-9,10-dihydroxy-4-megastigmaen-3-one (4) quercetin-3-galactoside (5) and 3-dimethoxy-5,6,4-trihydroxyflavon (6). All the isolates 1-6 were characterized by the combination of 1D (1H, 13C), 2D (COSY, HSQC and HMBC) NMR data and high resolution mass spectrometric analysis. In antibacterial assay, compound 1 showed moderate inhibitory activity against Escherichia coli and Salmonalla typhi. (author)