GARDINERIN, A BIOLOGICALLY ACTIVE ACETOGENIN FROM THE SRI LANKAN GONIOTHALAMUS GARDINERI HOOK. F. AND THOMSON

Objective: The study was undertaken to isolate biologically active compounds from Goniothalamus gardineri, a plant endemic to Sri Lanka. Methods: Roots and flowers of Goniothalamus gardineri were extracted into dichloromethane and methanol. A new acetogenin, gardinerin isolated by column chromatography of the dichloromethane extract was structurally characterized using NMR and Mass spectroscopies. It was found to be mosquito larvicidal (against 2nd instar larvae of Aedes aegypti), cytotoxic (in the brine shrimp assay) and antioxidant (DPPH assay). Results: Gardinerin exhibited potent mosquitolarvicidal activity (LC50 = 0.0744±0.37 ppm.), cytotoxicity (LC50 = 1.5±0.37 ppm) and antioxidant activity (IC50 =10.02±0.01 ppm). The same extract furnished (5R)-goniothalamin. The hexane extract of the flowers of G. gardineri yielded poriferesterol and stigmast-4, 22-dien-3-one.Conclusion: The endemic plant G. gardineri has yielded an acetogenin possessing highly potent antioxidant, cytotoxic and mosquitolarvicidal activity. Â

Near-IR absorption of porphyrin methylcarbocations

Syntheses of stabilized meso-and β-carbocations of nickel(II) porphyrins are reported and compared. A novel dimeric porphyrin cation absorbing at 1030 nm is also described. © 2003 Elsevier Ltd. All rights reserved

Investigations on the directive effects of a single meso-substituent via nitration of 5,12,13,17,18-pentasubstituted porphyrins: Syntheses of conjugated β-nitroporphyrins

Vilsmeier formylation of 5-substituted 1,9-diunsubstituted dipyrromethanes afforded 1,9-diformyldipyrromethanes in good yields. Their MacDonald condensation with tetra-β-alkyldipyrromethanes produced 5,12,13,17,18-pentasubstituted porphyrins. A meso-electron-donating group, presumably acting by destabilizing the porphyrin a2u ground state, directs the nitrations to the meso-carbons. β-Nitration takes place on porphyrins bearing a meso-electron-withdrawing group. Unhindered β-nitro groups are shown to exert stronger electronic effects relative to meso-nitro groups by conjugating effectively with the porphyrin macrocycle. © 2001 Elsevier Science Ltd

Syntheses of carbon-carbon linked carboranylated porphyrins for boron neutron capture therapy of cancer

Total syntheses of six carboranyl-containing porphyrins bearing 33-44% boron by weight for potential application in boron neutron capture therapy of tumors, are described; these novel compounds feature carbon-carbon linkages between the carboranyl groups and the meso-phenyl substituents. (C) 2000 Published by Elsevier Science Ltd

Singlet oxygen generation and dark toxicity of a nido- and a closo-carboranylporphyrin

The dark toxicity and singlet oxygen quantum yields of the zinc(II) complexes of the nido- and closo-carboranylporphyrins 4 and 5 are reported. Both carboranylporphyrins show very low toxicity towards V79 hamster lung fibroblast cells (IC50 \u3e 500 μM), display similar absorption and fluorescence emission spectra, and are efficient producers of singlet oxygen (quantum yields of 0.72 in CD3OD and 0.45 in CHCl3 were determined for 4 and 5, respectively). Our results indicate that the presence of nido- or c/oso-carborane cages bound via methylene linkages to the meso-phenyl groups, do not substantially alter the photosensitizing properties of porphyrin macrocycles. It is suggested that carboranylporphyrins could have dual application in the boron neutron capture therapy (BNCT) and photodynamic therapy (PDT) treatment of malignant brain tumors

Ab initio and \u3csup\u3e1\u3c/sup\u3eH NMR study of the Zn(II) complexes of a nido- and a closo-carboranylporphyrin

An ab initio study of a promising nido-carboranylporphyrin for the boron neutron capture therapy of tumors, and of its closo precursor is reported. Base-induced deboronation of neutral ZnDCP, believed to exist as a mixture of 3 stereoisomers, produces the tetraanionic ZnDCP4- as a complex mixture of isomers. 1H NMR data and ab initio calculations support these findings. The position of the axial pyridine ligand in ZnDCP4- and the orientation of the endo hydrogen atoms on the open faces of the nido-carborane cages significantly influence the total energy of the ZnDCP 4- structures. It is suggested that the cocktail of isomers possibly enhances the biological activity of tetra(nido-carboranyl) porphyrins, such as ZnDCP4-. Copyright © 2004 Society of Porphyrins & Phthalocyanines

Sulfonic acid polymers are potent inhibitors of HIV-1 induced cytopathogenicity and the reverse transcriptases of both HIV-1 and HIV-2

Four novel sulfonic acid polymers were evaluated for their in vitro HIV-1 and HIV-2 reverse transcriptase (RT) inhibitory activity and found to be equipotent against both RTs. The aromatic polymers demonstrated IC50 values that were approximately 103-fold lower than those observed with the aliphatic polymers. Among the aromatic polymers, poly(4-styrenesulfonic acid) (PSS) (MW 8000; IC50 = 0.02 μg/ml) was 3-fold more potent than poly(anetholesulfonic acid) (PAS) of approximately the same molecular weight range. The activity of PSS polymers increased in proportion to the size of the polymers and, relative to suramin, activity could be enhanced over 200-fold. These polymers also inhibited the cytopathic effect of HIV-1 at concentrations that were non-toxic to MT-4 cells. The potent RT inhibitory properties of these stable sulfonic acid polymers suggest that structure-activity studies are warranted to yield agents capable of inhibiting multiple stages of the viral process

TOTAL POLYPHENOL CONTENT AND ANTIOXIDANT AND CYTOTOXIC ACTIVITIES OF THE SRI LANKAN ENDEMIC PLANT GENUS SCHUMACHERIA

Objective: Schumacheriais a genus endemic to Sri Lanka distributed in lowland rain forests and mountain rain forests. The total polyphenol content and antioxidant and cytotoxic activities of hexane, dichloromethane and methanol extracts of stem-bark, root-bark, leaves and flowers of the three representative plant speciesS. castaneifolia, S. alnifolia and S. angustifolia belonging to the endemic genus Schumacheriaare reported. Methods: Antioxidant activity was determined using the DPPH (1,1-diphenyl-2-picrylhydrazine) radical scavenging assay. The total polyphenol content, expressed as the gallic acid equivalent, was determined using theFolin-Ciocaltue method and the cytotoxic activity was determined using the brine shrimp (Artemiasalina) assay.Results: The methanol extract of S. castaneifolia flowers (IC50 = 6.8 ± 0.1 ppm)and the methanol extracts of S. alnifolia stem-bark (IC50 =7.1 ± 0.4 ppm) and leaves (IC50 =8.3 ± 0.3 ppm) showed antioxidant activity higher than that of α-tocopherol(IC50 = 10.9 ± 4.3 ppm). The methanol extracts of S. alnifolia stem-bark (69.3 ± 6.9 mg g-1) and leaf (57.7 ± 0.0 mg g-1) extracts showed the highest polyphenol content closely followed by the methanol extracts of S. castaneifolia flowers (71.2 ± 0.6 mg g-1). The highest cytotoxic activity was exhibited by the methanol extract of S. castaneifolia flowers (LC50 = 1.3 ± 0.7 ppm), and all the other extracts showed comparatively less cytotoxic activity.Conclusion: S. castaneifolia and S. alnifolia exhibit potent bioactivitiesvalidating the ethnomedical claims where the former has been used for oral aphthous.Â