Flavonoids from Limnophila indica

Two flavonoids, (2S)-5,7,3',4'-tetramethoxyflavanone (1) and 5,7,2',5'-tetramethoxyflavone (2) together with three known flavonoids, 7-O-methylwogonin (3), skullcapflavone I (4) and 5-hydroxy-7,2'-dimethoxyflavone (5) were isolated from the whole plant of Limnophila indica. The structures of compounds 1-5 were elucidated on the basis of spectral and chemical studies.     

Elemanolide sesquiterpenes and eudesmane sesquiterpene glycosides from Centaurea hierapolitana

Two elemanolide sesquiterpenes and two eudesmane-type sesquiterpene glycosides named hierapolitanins A-D, were isolated, together with five known compounds, two flavones; hispidulin and jaceosidin, a flavon-C-glycoside, shaftoside, a flavonol glycoside, kaempferol-3-O-rutinoside and a neolignan, dehydrodiconiferyl alcohol from the aerial parts of Centaurea hierapolitana Boiss. (Asteraceae). Structure elucidations were based on spectroscopic evidence.     

Flavonoids from Cleistocalyx operculatus

Two flavonoids 3'-formyl-4',6'-dihydroxy-2'-methoxy-5'-methylchalcone and (2S)-8-formyl-5-hydroxy-7-methoxy-6-methylflavanone together with five known compounds, were isolated from the dried buds of Cleistocalyx operculatus. Their structures were determined on the basis of spectroscopic analyses (UV, IR, EIMS, (1)H, (13)C NMR and HMBC).     

Flavonoids from Andrographis lineata

Three flavonoids, 5,7,2',3',4'-pentamethoxyflavone (1), 2'-hydroxy-2,4',6'-tri methoxychalcone (2) and dihydroskullcapflavone I (3), together with 17,19,20-trihydroxy-5beta, 8alpha H, 9beta H,10alpha-labd-13-en-16,15-olactone (4), a known diterpenoid and six known flavonoids, 5-hydroxy-7,8-dimethoxyflavanone (5), 5-hydroxy-7,8,2',3',4'-pentamethoxyflavone (6), 5,2'-dihydroxy-7-methoxyflavanone (7), 5,2'-dihydroxy-7,8-dimethoxyflavone (8), 5,2'-dihydroxy-7-methoxyflavone (9) and 5,2'-dihydroxy-7-methoxyflavone 2'-O-beta-D-glucopyranoside (10) were isolated from the whole plant of Andrographis lineata. The structures of these compounds were elucidated on the basis of spectral and chemical studies.     

Flavonoids and andrographolides from Andrographis paniculata

Two flavonoids, identified as 5,7,2',3'-tetramethoxyflavanone and 5-hydroxy-7,2',3'-trimethoxyflavone, as well as several other flavonoids, andrographolide diterpenoids, and polyphenols, were obtained from the phytochemical investigation of the whole plant of Andrographis paniculata, a well known medicinal plant. The structures of these compounds were established with the aid of spectroscopic methods, including analysis by 2D NMR spectroscopy.     

Flavonoids from two Lonchocarpus species of the Yucatan Peninsula

Leaves, stem bark and root of Lonchocarpus xuul and Lonchocarpus yucatanensis were studied separately. A chalcone, 2',4-dimethoxy-6'-hydroxylonchocarpin (), and the flavones 5,4'-dihydroxy-3'-methoxy-(6:7)-2,2-dimethylpyranoflavone (2) and 5,4'-dimethoxy-(6:7)-2,2-dimethylpyrano-flavone (3), together with the known carpachromene (4), were isolated from the leaves of both species. Similarly, the previously reported flavans xuulanin (5) and 3beta-methoxyxuulanin (6), together with the novel 3beta,4beta,5-trimethoxy-4'-hydroxy-(6:7)-2,2-dimethylpyranoflavan (7), 3-hydroxy-4,5-dimethoxy-(6:7)-2,2-dimethyl-pyranoflavan (8), and 3,4-dihydroxy-5-methoxy-(6:7)-2,2-dimethylpyranoflavan (10), were isolated from the stem bark and root of both species. Finally, the known 2',4'-dihydroxy-3'-(3-methylbut-2-enyl) chalcone (13) was obtained from the root of L. xuul only. The structures of the various metabolites were established by interpretation of their spectroscopic data.     

Evaluation of the antioxidant and cytotoxic activity of arzanol, a prenylated alpha-pyrone-phloroglucinol etherodimer from Helichrysum italicum subsp.microphyllum

Various phenolics and (mero)terpenoids from Helichrysum italicum subsp. microphyllum, a plant endemic to Sardinia, were investigated for their capacity to inhibit non-enzymatic lipid peroxidation. These compounds were studied in simple in vitro systems, under conditions of autoxidation and of iron (EDTA)-mediated oxidation of linoleic acid at 37 degrees C. Arzanol, a pyrone-phloroglucinol etherodimer, and helipyrone, a dimeric pyrone, showed antioxidant activity, and could protect linoleic acid against free radical attack in assays of autoxidation and EDTA-mediated oxidation. Methylarzanol, as well as the sesquiterpene alcohol rosifoliol, showed a decreased, but still significant, protective effect against linoleic acid oxidation. Arzanol and helipyrone were also tested in an assay of thermal (140 degrees C) autoxidation of cholesterol, where arzanol showed significant antioxidant activity. The cytotoxicity of arzanol was further evaluated in VERO cells, a line of fibroblasts derived from monkey kidney. Arzanol, at non-cytotoxic concentrations, showed a strong inhibition of TBH-induced oxidative stress in VERO cells. The results of the present work suggest that the natural compound arzanol exerts useful antioxidant properties in different in vitro systems of lipid peroxidation.     

Flavonoids from the aquatic plant Eriocaulon buergerianum

Four flavonoids including (2S)-3',4'-methylenedioxy-5,7-dimethoxyflavan and hispidulin 7-(6-E-p-coumaroyl-beta-D-glucopyranoside), and one tocopherol were isolated from the capitulum of Eriocaulon buergerianum KOERN. Their structures were established by spectral and chemical evidence.     

Flavonoids from Tephrosia aequilata

From the roots of the plant Tephrosia aequilata Baker, five flavonoids were isolated of which, 3,4:8,9-dimethylenedioxypterocarpan is reported for the first time. Its structure and those of the already known flavonoids were established by physical and spectroscopic analysis. Application of 2D NMR techniques was useful for complete characterization of the new pterocarpan as well as the other known flavonoids.     

Flavonoids of Ochna afzelii

Fractionation of the methanolic extract of Ochna afzelii stem bark has resulted in the isolation of two biflavonoids afzelones A and B along with five known flavonoids, calodenins A and B, afzelone C, 4',5-dimethoxy-6,7-methylenedioxyisoflavone, 4',5,7-trimethoxyisoflavone and the glucoside lanceoloside A. Their structures were determined using spectroscopic and chemical methods.     

Antifeedant activity of ethanolic extract from Flourensia oolepis and isolation of pinocembrin as its active principle compound

The ethanolic extract from Flourensia oolepis aerial parts showed strong antifeedant activity against the pest larvae, Epilachna paenulata, with an antifeedant index (AI%) of 99.1% at 100 μg/cm². Based on chromatographic fractionation of the extract, guided by bioassays on E. paenulata, the flavanone pinocembrin (1) was isolated as the most active principle. In a choice assay, compound 1 showed strong antifeedant activity against E. paenulata, Xanthogaleruca luteola and Spodoptera frugiperda with an AI% of 90, 94 and 91% (p < 0.01) respectively, at 50 μg/cm². The dosages necessary for 50% feeding inhibition of the insects (ED₅₀) were 7.98, 6.13 and 8.86 μg/cm², respectively. The feeding inhibitory activity of 1 against E. paenulata was compared with the activity of other structurally related flavonoids like naringenin, which was inactive up to 100 μg/cm², catechin which was nearly 6 times less active than 1, and quercetin which was equally active as 1. The effect of these on the feeding behavior of E. paenulata was also studied.     

Flavonoids, triterpenoids and a lignan from Vitex altissima

A new tetrahydrofuranoid lignan, altissinone (1) and a new acylated flavone C-glucoside, 2'-O-p-hydroxybenzoylorientin (2), were isolated in addition to several known triterpene acids and flavonoids from the ethyl acetate extractives of the leaves of Vitex altissima. The structures of the compounds were established based on interpretation of high resolution NMR (HMQC, HMBC and NOESY) spectral data. The ethyl acetate extract exhibited significant anti-inflammatory activity in rat paw edema model. The flavonoids and triterpene acids showed moderate antioxidant and 5-lipoxygenase enzyme inhibitory activities, respectively.