Antioxidant secondary metabolites from Geranium lasiopus Boiss. & Heldr

Chromatographic studies on the EtOAc soluble portion of the MeOH extract of Geranium lasiopus led to the isolation of eight flavonoids (kaempferol (1), quercetin (2), quercetin 3-O-β-glucopyranoside (3), quercetin 3-O-β-galactopyranoside (4), kaempferol 3-O-α-rhamnopyranosyl-(1?→?6)-β-glucopyranoside (5), quercetin 3-O-α-rhamnopyranosyl-(1?→?6)-β-glucopyranoside (6), kaempferol 3-O-α-rhamnopyranosyl-(1?→?2)-β-glucopyranoside (7) and quercetin 3-O-α-rhamnopyranosyl-(1?→?2)-β-glucopyranoside (8)), two simple phenolic compounds (gallic acid (9) and its methyl ester (10)) and a hydrolysable tannin (pusilagin (11)). The structures of the compounds were elucidated by 1- and 2-dimensional NMR techniques ((1)H, (13)C, COSY, HMBC, HMQC) and ESI-TOF-MS spectrometry. Inhibitory effects on H(2)O(2)-induced lipid peroxidation in human red blood cells of the different extracts of G. lasiopus, as well as isolated compounds, were investigated. All tested compounds showed comparable or higher activity than that of ascorbic acid and trolox.     

Chemical constituents and antibacterial activity of Melastoma malabathricum L

The aqueous methanolic extracts of Melastoma malabathricum L. exhibited antibacterial activity when assayed against seven microorganisms by the agar diffusion method. Solvent fractionation afforded active chloroform and ethyl acetate fractions from the leaves and the flowers, respectively. A phytochemical study resulted in the identification of ursolic acid (1), 2α-hydroxyursolic acid (2), asiatic acid (3), β-sitosterol 3-O-β-D-glucopyranoside (4) and the glycolipid glycerol 1,2-dilinolenyl-3-O-β-D-galactopyanoside (5) from the chloroform fraction. Kaempferol (6), kaempferol 3-O-α-L-rhamnopyranoside (7), kaempferol 3-O-β-D-glucopyranoside (8), kaempferol 3-O-β-D-galactopyranoside (9), kaempferol 3-O-(2″,6″-di-O-E-p-coumaryl)-β-D-galactopyranoside (10), quercetin (11) and ellagic acid (12) were found in the ethyl acetate fraction. The structures of these compounds were determined by chemical and spectral analyses. Compounds 1-4, the flavonols (6 and 11) and ellagic acid (12) were found to be active against some of the tested microorganisms, while the kaempferol 3-O-glycosides (7-9) did not show any activity, indicating the role of the free 3-OH for antibacterial activity. Addition of p-coumaryl groups results in mild activity for 10 against Staphylococcus aureus and Bacillus cereus. Compounds 2-5, 7 and 9-12 are reported for the first time from M. malabathricum. Compound 10 is rare, being reported only once before from a plant, without assignment of the double bond geometry in the p-coumaryl moiety.     

Metabolite profiling and antioxidant activity of Prunus padus L. flowers and leaves

Six phenolics were obtained from the leaves of Prunus padus by activity-guided isolation: isorhamnetin 3-O-β-xylopyranosyl-(1?→?2)-β-galactopyranoside (1), astragalin (2), hyperoside (3), quercetin 3-O-β-xylopyranosyl-(1?→?2)-β-galactopyranoside (4), quercetin 3-O-β-xylopyranosyl-(1?→?2)-β-glucopyranoside (5) and chlorogenic acid (6). The antioxidant potential of 70% methanolic extracts from the flowers and leaves collected over the growing season was evaluated using the 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging and 2,2′-azobis-(2-amidinopropane) dihydrochloride (AAPH)-induced linoleic acid (LA) peroxidation tests in relation to the contents of the isolates 1-6, total phenolics, total proanthocyanidins and total quercetin. The IC?? values were expressed in gram dry weight per gram of DPPH or LA, respectively, and were in the range of 1.42-2.42 for the DPPH test and 1.78-4.92 for the LA peroxidation, with superior activity found for the flowers and the autumn leaves. Significant linear correlation of these values to the sum of proanthocyanidins and compounds 1-6 (R2?>?0.87) showed that the listed phenolics are synergists of the tested activity.     

Identification of the antioxidant principles of Polyalthia longifolia var. pendula using TEAC assay

Activity-guided fractionation of the ethanolic extract of the leaves of the Polyalthia longifolia var. pendula led to the identification of quercetin (1), quercetin-3-O-β-glucopyranoside (2), kaempferol-3-O-α-rhamnopyranosyl-(1 → 6)-β-galactopyranoside (3), kaempferol-3-O-α-rhamnopyranosyl-(1 → 6)-β-glucopyranoside (4), rutin (5) and allantoin (6) as the active constituents from the butanol fraction. Compounds 2-4 are reported for the first time from this natural source. Structures of the compounds were confirmed on the basis of their 1D and 2D NMR coupled with other spectroscopic methods. All the isolated compounds and the fractions were evaluated for their antioxidant potential using the TEAC assays and it was found that the activity of the active fraction was due to quercetin (1) and its glycosides (2 and 5), with TEAC values of 4.10, 1.91 and 2.38 mM, respectively, while the kaempferol glycosides were found to be inactive. This is the first study on the antioxidant activity of this plant species.     

Phytochemical constituents and chemosystematic significance of Chrozophora tinctoria (L.) Raf

Twelve compounds were isolated from Chrozophora tinctoria (L.) Raf. They were identified as kaempferol, kaempferol 3-O-β-glucopyranoside, kaempferol 3-O-(6″-α-rhamnopyranosyl)-β-glucopyranoside, quercetin, quercetin 3-O-β-glucopyranoside, quercetin 3-O-(6″-α-rhamnopyranosyl)-β-glucopyranoside, apigenin, apigenin 7-O-β-glucopyranoside, acacetin, gallic acid, methyl gallate and β-sitosterol-3-O-β-glucopyranoside. Their structures were elucidated by chemical and spectral methods. Furthermore, chemosystematics of the isolated compounds is briefly discussed. It was indicated that C. tinctoria is the only species of Chrozophora that has the capability to synthesis kaempferol aglycone and their glycosides, and the finding is supported by its distinct morphological and anatomical aspects.     

One new diphenylmethane glycoside from the leaves of Psidium guajava L

To investigate the chemical constituents of Psidium guajava L, the EtOH/H(2)O extract of the fresh leaves was subjected to various chromatography. One diphenylmethane, one benzophenone, and eight flavonoids were isolated and elucidated as 2,6-dihydroxy-3-formaldehyde-5-methyl-4-O-(6″-O-galloyl-β-D-glucopyranosyl)-diphenylmethane (1), 2,6-dihydroxy-3,5-dimethyl-4-O-(6″-O-galloyl-β-D-glucopyranosyl)-benzophenone (2), kaempferol (3), quercetin (4), quercitrin (5), isoquercitrin (6), guaijaverin (7), avicularin (8), hyperoside (9), reynoutrin (10) by spectroscopic methods, including 1D and 2D NMR and HR-ESI-MS spectrometry as well as by comparison with published data. Compounds 5 and 10 are obtained from P. guajava for the first time, and compound 1 is a new diphenylmethane compound.     

Activity-guided isolation and identification of free radical-scavenging components from various leaf extracts of Sorbus aria (L.) Crantz

Nine phenolics were obtained from the leaves of Sorbus aria (L.) Crantz by activity-directed isolation: isorhamnetin 3-O-β-glucopyranoside (1), astragalin (2), isoquercitrin (3), hyperoside (4), kaempferol 3-O-β-glucopyranoside-7-O-α-rhamnopyranoside (5), quercetin 3-O-β-glucopyranoside-7-O-α-rhamnopyranoside (6), rutin (7), chlorogenic acid (8) and neochlorogenic acid (9). The isolates were identified by spectral methods (UV, (1)H- and (13)C-NMR, COSY, HMQC and HMBC), and their free radical-scavenging activity was tested using the l,l-diphenyl-2-picrylhydrazyl (DPPH) method. The antioxidant potential of the different extracts obtained in the fractionation process was evaluated using the DPPH test in relation to the HPLC contents of the isolates 1-9, total phenolics and total proanthocyanidins. Among the analytes tested, superior activity was expressed by isoquercitrin (3, EC(50)?= 2.76 mg L(-1)) and the ethyl acetate extract (EC(50)?= 2.99 mg L(-1)). Five strongly active isolates 3, 6, 7, 8 and 9 were found to be major components and to be principally responsible for the radical-scavenging activity of S. aria extracts.     

Two oleananes from Ammannia auriculata Willd

Two new compounds: 3-β,15-α,23,28-tetrahydroxyolean-12-en-3-O-arabinopyaranoside and 3-β,23,28-trihydroxy-olean-12-en-3-O-β-D-glucopyranoside were isolated from the aerial parts of Ammania auriculata along with the known compounds kaempferol, β-sitosterol-3-O-β- D-glucoside, 2-α,3-β,23-trihydroxyolean-12-en-28-oic acid-28-O-β-D-glucopyranoside, quercetin, kaempferol-3-O-α-L-arabinofuranoside, kaempferol-3-O-β-D-xylopyranoside and ellagic acid. Structures of these compounds were elucidated on the basis of their spectroscopic data (NMR, UV, MS and IR spectra). The antioxidant activities of the total extract, the fractions CH(2)Cl(2), EtOAc and the remaining aqueous together with the compounds 1, 6 and 9 were comparable with that of the standard antioxidant, ascorbic acid.     

Inhibitory effects of constituents from Euphorbia lunulata on differentiation of 3T3-L1 cells and nitric oxide production in RAW264.7 cells

A new flavonol galactopyranoside, myricetin 3-O-(2',3'-digalloyl)-β-D-galactopyranoide (1), and 23 known constituents, including myricetin 3-O-(2'-galloyl)-β-D-galactopyranoide (2), myricitrin (3), myricetin (4), quercetin 3-O-(2', 3'-digalloyl)-β-D-galactopyranoide (5), quercetin 3-O-(2'-galloyl)-β-D-galactopyranoide (6), hyperin (7), isoquercetrin (8), quercetin (9), kaempferol (10), apigenin (11), luteolin (12), 3-O-methylquercetin (13), 5,7,2',5'-tetrahydroxyflavone (14), 1,3,4,6-tetra-O-galloyl-β-D-glucose (15), 1,2,6-tri-O-galloyl-β-D-glucose (16), 1,3,6-tri-O-galloyl-β-D-glucose (17), gallic acid (18), protocatechuic acid (19), 3,4,5-trimethoxybenzoic acid (20), 2,6-dihydroxyacetophenone (21), 3,3'-di-O-methylellagic acid (22), ellagic acid (23) and esculetin (24) were isolated from Euphorbia lunulata Bge. Their structures were determined by spectroscopic analysis. Isolated hydrolysable tannins, flavonoids, and flavonol galactopyranoside gallates showed significant inhibition of the differentiation of 3T3-L1 preadipocytes and triglyceride accumulation in maturing adipocytes, and nitric oxide production in RAW 264.7 cells.     

Anti-inflammatory and free radial scavenging activities of the constituents isolated from Machilus zuihoensis

A new biflavonol glycoside, quercetin-3-O-β-D-glucopyranoside-(3'→O-3')-quercetin-3-O-β-D-galactopyranoside (9), together with eight known compounds was isolated for the first time from the leaves of Machilus zuihoensis Hayata (Lauraceae). The structure of compound 9 was elucidated by various types of spectroscopic data analysis. Analysis of the biological activity assay found that compound 9 showed significant superoxide anion scavenging activity (IC?? is 30.4 μM) and markedly suppressed LPS-induced high mobility group box 1 (HMGB-1) protein secretion in RAW264.7 cells. In addition, the HMGB-1 protein secretion was also inhibited by quercitrin (3), ethyl caffeate (6), and ethyl 3-O-caffeoylquinate (7) treatment. In the LPS-stimulated inducible nitric oxide synthase (iNOS) activation analysis, two known compounds, quercetin (1) and ethyl caffeate (6), were found to markedly suppress nitric oxide (NO) production (IC?? value, 27.6 and 42.9 μM, respectively) in RAW264.7 cells. Additionally, it was determined that ethyl caffeate (6) down-regulated mRNA expressions of iNOS, IL-1β, and IL-10 in the LPS-treatment of RAW264.7 cells via a suppressed NF-kB pathway. These results suggested for the first time that the new compound 9 and other constituents isolated from M. zuihoensis have potential anti-inflammatory and superoxide anion scavenging effects. These constituents may be useful for treating various inflammatory diseases.     

Antioxidant, anti-glycation and anti-inflammatory activities of phenolic constituents from Cordia sinensis

Nine compounds have been isolated from the ethyl acetate soluble fraction of C. sinensis, namely protocatechuic acid (1), trans-caffeic acid (2), methyl rosmarinate (3), rosmarinic acid (4), kaempferide-3-O-β-D-glucopyranoside (5), kaempferol-3-O-β-D-glucopyranoside (6), quercetin-3-O-β-D-glucopyranoside (7), kaempferide-3-O-α-L-rhamnopyranosyl (1→6)-β-D-glucopyranoside (8) and kaempferol-3-O-α-L-rhamno-pyranosyl (1→6)-β-D-glucopyranoside (9), all reported for the first time from this species. The structures of these compounds were deduced on the basis of spectroscopic studies, including 1D and 2D NMR techniques. Compounds 1-9 were investigated for biological activity and showed significant anti-inflammatory activity in the carrageen induced rat paw edema test. The antioxidant activities of isolated compounds 1-9 were evaluated by the DPPH radical scavenging test, and compounds 1, 2, 4 and 7-9 exhibited marked scavenging activity compared to the standard BHA. These compounds were further studied for their anti-glycation properties and some compounds showed significant anti-glycation inhibitory activity. The purity of compounds 2-5, 8 and 9 was confirmed by HPLC. The implications of these results for the chemotaxonomic studies of the genus Cordia have also been discussed.     

Chemical composition and antioxidant activities of extracts from Apocyni Veneti Folium

An expeditious and effective HPLC-UV method has been developed for the simultaneous determination of seven major flavonoids in Apocyni Veneti Folium (AVF) extract. The chemical profile of seven flavonoids, including quercetin-3-O-β-D-glc(2?→?1)-β-D-glucoside, rutin, isoquercetin, kaempferol-3-O-β-D-glucoside, quercetin-3-O-(6″-O-malonyl)-β-D-glucoside, quercetin and kaempferol was acquired by HPLC-UV. The analysis was performed on a Diamosil C18 analytical column with a gradient solvent system of acetonitrile-0.1% aqueous acetic acid. Full validation of the method was carried out (linearity, reproducibility, repeatability, accuracy and limit of detection). The results indicated that the contents of investigated flavonoids in Apocyni Veneti Folium varied significantly from habitat to habitat, with contents ranging from 0.01 to 5.57 mg g?1. The antioxidant activity results demonstrate that the seven flavonoids showed great efficiency in scavenging DPPH radicals. The high content of flavonoid components of AVF could be responsible for its high antioxidant activity. This study provides powerful evidence for the relationship between the chemical ingredients of and bioactivity in AVF.     

Phenolics of Moringa oleifera leaves

Five flavonol glycosides characterised as kaempferide 3-O-(2',3'-diacetylglucoside), kaempferide 3-O-(2'-O-galloylrhamnoside), kaempferide 3-O-(2'-O-galloylrutinoside)-7-O-alpha-rhamnoside, kaempferol 3-O-[beta-glucosyl-(1 --> 2)]-[alpha-rhamnosyl-(1 --> 6)]-beta-glucoside-7-O-alpha-rhamnoside and kaempferol 3-O-[alpha-rhamnosyl-(1 --> 2)]-[alpha-rhamnosyl-(1 --> 4)]-beta-glucoside-7-O-alpha-rhamnoside together with benzoic acid 4-O-beta-glucoside, benzoic acid 4-O-alpha-rhamnosyl-(1 --> 2)-beta-glucoside and benzaldehyde 4-O-beta-glucoside have been isolated from methanolic extract of Moringa oleifera leaves. Also obtained from the same extract were known compounds, kaempferol 3-O-alpha-rhamnoside, kaempferol, syringic acid, gallic acid, rutin and quercetin 3-O-beta-glucoside. Their structures were determined using spectroscopic methods as well as comparison with data from known compounds.     

Antioxidant flavonol glycosides from Elaeocarpus serratus and Filicium decipiens

Chemical investigation of the leaves of Elaeocarpus serratus yielded myricitrin (1), mearnsetin 3-O-β-D-glucopyranoside (2), mearnsitrin (3), tamarixetin 3-O-α-L-rhamnopyranoside (4) and the fruits of Filicium decipiens yielded three flavonol glycosides, kaempferol 3-O-rutinoside (5), kaempferol 3-O-robinobioside (6) and trifolin (7). Compound 1 showed strong antioxidant activity against DPPH.     

Two new flavone C-glycosides from Trollius ledebourii

Two new flavone C-glycosides, trollisin A (1) and trollisin B (2), along with seven known flavonoids, isoswertisin (3), isoswertiajaponin (4), orientin (5), 2″-O-β-L-galactopyranosylvitexin (6), 2″-O-β-L-galactopyranosylorientin (7), neodiosmin (8) and acacetin-7-O-neohesperidoside (9) were isolated from the flowers of Trollius ledebourii REICHB. The structures of the new compounds were elucidated based on spectral analysis, including MS, 1D- and 2D-NMR experimentation.     

Acylated flavonol glycosides with anti-complement activity from Persicaria lapathifolia.

During a search for biologically active compounds from traditional medicines, a crude extract of Persicaria lapathifolia was found to have anti-complement activity. Bioassay-guided chromatographic separation of the active constituents led to the isolation of a new acylated kaempferol glycoside (1) and three known acylated quercetin glycosides (2-4). The structures of compounds 1-4 were characterized as kaempferol 3-O-beta-D-(6"-p-hydroxybenzoyl)-galactopyranoside, quercetin 3-O-beta-D-(6"-feruloyl)-galactopyranoside, quercetin 3-O-beta-D-(2"-galloyl)-rhamnopyranoside and quercetin 3-O-beta-D-(2"-galloyl)-glucopyranoside, respectively. Compounds 1-4 showed strong anti-complement activity (IC50 values of 4.3, 9.7, 3.9 and 7.6 x 10(-5) M, respectively) on the classical pathway of the complement. On the other hand, six isolated flavonol glycosides (5-10) did not show any activity on this system.     

Three new flavonol C-glycosides from Sida cordifolia Linn

Three new flavonol C-glycosides: 3′-(3″,7″-dimethyl-2″,6″-octadiene)-8-C-β-D-glucosyl-kaempferol 3-O-β-D-glucoside (1), 3′-(3″,7″-dimethyl-2″,6″-octadiene)-8-C-β-D-glucosyl-kaempferol 3-O-β-D-glucosyl [1→4]-α-D-glucoside (2) and 6-(3″-methyl-2″-butene)-3′-methoxyl-8-C-β-D-glucosyl-kaempferol 3-O-β-D-glucosyl [1→4]-β-D-glucoside (3) have been isolated from 80% ethanolic extract of the aerial parts of Sida cordifolia Linn followed by partitioning with ethyl acetate. Structures were established by chemical and spectroscopic methods.     

Chemical Constituents of the Aerial Part of Celastrus Hypoleucus

Fourteen compounds including eight triterpenoids, 12‐oleanaen‐3β‐ol (β‐amyrin) ( 1 ), 12‐oleanaen‐3β‐caffeate ( 2 ), 9(11),12‐oleanadien‐3β‐ol ( 3 ), 9(11),12‐oleanadien‐3‐one ( 4 ), 9(11),12‐oleanadien‐3 β‐caffeate ( 5 ), friedela‐3‐one (friedelin) ( 6 ), friedela‐3‐one‐29‐ol ( 7 ), and 12‐gammateraen‐3 β‐ol (tetrehymanol) ( 8 ); one steroid, β‐sitosterol ( 9 ); one long‐chain acid, octadecadienoic acid ( 10 ); two esters, ester of n‐octaolecyl‐4‐hydroxy‐cinnamate ( 11 ), and ester of n‐octadecyl‐caffeic acid ( 12 ); one diterpene, 8β,19‐dihydroxy‐3‐oxopimar‐15‐ene ( 13 ); one sesquiterpene, 1β,2β,9α‐trihydroxy‐β‐dihydroagarofuran ( 14 ) were isolated from the aerial part of Celastrus hypoleucus. These compounds were characterized and identified by physical and spectral methods. All compounds were isolated for the first time from this plant. Among them 12‐oleanaen‐3β‐caffeate ( 2 ) and 9(11),12‐oleanadien‐3β‐caffeate ( 5 ) are two new compounds, and ester of n‐octadecyl‐caffeic acid (12) possessed antilipoperoxidative effect by specifically scavenging the hydroxyl free radical (?OH) in vitro.     

Isolation and characterisation of novel antioxidant constituents of Croton zambesicus leaf extract

A 1,1-diphenyl-2-picrylhydrazyl (DPPH)-activity-directed fractionation was used to target antioxidant constituents of the ethyl acetate fraction obtained from a 20% aqueous methanol crude extract of Croton zambesicus leaf. Repeated column chromatography of the fraction on silica gel and Sephadex LH-20 led to the isolation of a new natural product, identified as quercetin-3-O-β-6″(p-coumaroyl) glucopyranoside-3'-methyl ether, helichrysoside-3'-methyl ether (1), along with kaempferol-3-O-β-6″(p-coumaroyl) glucopyranoside, tiliroside (2) and apigenin-6-C-glucoside, isovitexin (3) as the antioxidant constituents. The structures of the isolated compounds were elucidated using spectroscopic techniques, namely NMR (1D and 2D) and mass spectrometry. Compounds 1 and 2 are reported from this species for the first time. In the qualitative antioxidant assay, the three isolated compounds instantly bleached the DPPH (0.2% MeOH) purple colour indicating antioxidant activity. In the quantitative antioxidant assay, all the isolated compounds demonstrated weak antioxidant activity compared to quercetin and rutin used as positive control antioxidant agents. The compounds displayed little to no cytotoxicity against Vero cells in an in?vitro assay. The presence of these antioxidant compounds in the leaf extract of C. zambesicus could provide a rationale for the ethnomedicinal use of the plant in the management of oxidative-stress-related diseases in folk medicine.     

Antioxidant galloylated flavonol glycosides from Calliandra haematocephala

Three new acylated quercetin rhamnosides have been isolated from the leaves and stem of Calliandra haematocephala Hassk. (Fabaceae) and their structures were established as quercitrin 2'-O-caffeate (1), quercitrin 3'-O-gallate (2) and quercitrin 2',3'-di-O-gallate (3). Also, 17 known compounds were identified as gallic acid (4), methyl gallate (5), caffeic acid (6), myricitrin (7), quercitrin (8), myricetin 3-O-beta-D-4C1-glucopyranoside (9), afzelin (10), isoquercitrin (11), myricetin 3-O-(6'-O-galloyl)-beta-D-glucopyranoside (12), myricitrin 2'-O-gallate (13), quercitrin 2'-O-gallate (14), afzelin 2'-O-gallate (15), myricitrin 3'-O-gallate (16), afzelin 3'-O-gallate (17), 1,2,3,4,6-penta-O-galloyl-beta-D-4C1-glucopyranose (18), myricitrin 2',3'-di-O-gallate (19), quercetin 3-O-methyl ether (20), for the first time from the genus Calliandra except for 6. Compounds 7, 8, 13, 14, 16 and 19 exhibited moderate to strong radical scavenging properties on lipid peroxidation, hydroxyl radical, superoxide anion generation and DPPH radical in comparison with that of quercetin as a positive control in vitro. Compounds 7 and 8 exhibited lethal effect towards brine shrimp Artemia salina.