Research

133 KiB

Open AccessShort Note

(-)-b-D-18–Glucopiranosyl-9,15-dihydroxy Kaurenoate, a New Diterpene Glycoside from Ageratina vacciniaefolia

by Rubén Torrenegra, Jorge Robles, Julio Pedrozo and Beatriz Pescador

Molecules 1999, 4(4), M92; https://doi.org/10.3390/M92 - 16 Apr 1999

Cited by 5 | Viewed by 3593

From leaves and flowers of Ageratina vacciniaefolia we have isolated several compounds: a flavonoid, a diterpene and a new compound identified as (-)-b-D-18–glucopiranosyl-9,15-dihydroxy kaurenoate (see the formula).[...] Full article

(This article belongs to the Section Molbank Section of Molecules, 1997-2001)

93 KiB

Open AccessShort Note

Plumbagin from Diospyros olen

by Philip H. Evans, William S. Bowers, Marc Litaudon and Thierry Sevenet

Molecules 1999, 4(4), M93; https://doi.org/10.3390/M93 - 16 Apr 1999

Cited by 10 | Viewed by 4285

Abstract

Plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) (CAS Reg. No. 481-42-5) was isolated from the bark of Diospyros olen (Ebenaceae) via an antibiotic guided biological assay using the bacterium Pseudomonas solanacearum. D. olen bark, collected in New Caledonia, was extracted with dichloromethane and components separated by flash chromatography [...] Read more.

Plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) (CAS Reg. No. 481-42-5) was isolated from the bark of Diospyros olen (Ebenaceae) via an antibiotic guided biological assay using the bacterium Pseudomonas solanacearum. D. olen bark, collected in New Caledonia, was extracted with dichloromethane and components separated by flash chromatography on silica.[...] Full article

(This article belongs to the Section Molbank Section of Molecules, 1997-2001)

110 KiB

Open AccessShort Note

A New Diglycoside of Diterpene from Ageratina vacciniaefolia

by Rubén Torrenegra, Jorge Robles, Julio Pedrozo and Beatriz Pescador

Molecules 1999, 4(4), M94; https://doi.org/10.3390/M94 - 16 Apr 1999

Cited by 4 | Viewed by 3367

Abstract

From leaves and flowers of Ageratina vacciniaefolia [1-7] we have isolated several compounds: a flavonoid, a diterpene [8] and a new compound identified as b-D-glucopyranosil ester of (-)17-(bglucopiranosyloxyl)- 16-hydroxy-kauran-19-oic acid (see the formula).[...] Full article

(This article belongs to the Section Molbank Section of Molecules, 1997-2001)

76 KiB

Open AccessArticle

Benzothiazole Derivatives. 48. Synthesis of 3-Alkoxycarbonylmethyl-6-bromo-2-benzothiazolones and 3-Alkoxycarbonylmethyl-6-nitro-2-benzothiazolones as Potential Plant Growth Regulators

by Dusan Loos, Eva Sidoova and Viktor Sutoris

Molecules 1999, 4(4), 81-93; https://doi.org/10.3390/40400081 - 26 Mar 1999

Cited by 39 | Viewed by 8146

Abstract

3-Alkoxycarbonylmethyl-6-bromo- and 3-alkoxycarbonylmethyl-6-nitro-2-benzothiazolones were synthesized by reaction of alkylesters of halogenoacetic acids with 6-bromo-2-benzothiazolones and 6-nitro-2-benzothiazolones respectively. The compounds were tested for plant growth stimulating activity on wheat (Triticum aestivum). The bromo derivatives manifested 25.4 % average stimulating activity in comparison [...] Read more.

3-Alkoxycarbonylmethyl-6-bromo- and 3-alkoxycarbonylmethyl-6-nitro-2-benzothiazolones were synthesized by reaction of alkylesters of halogenoacetic acids with 6-bromo-2-benzothiazolones and 6-nitro-2-benzothiazolones respectively. The compounds were tested for plant growth stimulating activity on wheat (Triticum aestivum). The bromo derivatives manifested 25.4 % average stimulating activity in comparison with the control. The stimulation activity of the nitro derivatives was not significant. Optimal structures of the compounds were obtained by a MMPI method, atomic charges and dipole moments were calculated by a semiempirical AM1 method. On the basis of molecular electrostatic potential it has been found that the biological activity of synthesized compounds depends on charge distribution in the molecules. Full article

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30 KiB

Open AccessArticle

A Study of Acid-Base Equilibria in Acetonitrile Systems of 2-Halo(Cl,Br,I)-4-nitropicoline(3,5,6) N-oxides

by Ewa Kaczmarczyk, Aniela Puszko, Jadwiga Lorenc and Lech Chmurzynski

Molecules 1999, 4(4), 94-103; https://doi.org/10.3390/40400094 - 29 Mar 1999

Cited by 5 | Viewed by 8964

Abstract

An attempt has been made to determine potentiometrically (1) acid dissociation constants of cations obtained by protonation of nine trisubstituted pyridine N-oxides, namely 2-halo(Cl, Br and I)-4-nitropicoline N-oxides with the methyl group at positions 3, 5, and 6, as well as (2) the [...] Read more.

An attempt has been made to determine potentiometrically (1) acid dissociation constants of cations obtained by protonation of nine trisubstituted pyridine N-oxides, namely 2-halo(Cl, Br and I)-4-nitropicoline N-oxides with the methyl group at positions 3, 5, and 6, as well as (2) the cationic homoconjugation constants of these cationic acids with conjugated N-oxides in acetonitrile. On the basis of the substitution effect, variations of the acid dissociation constants of the trisubstituted pyridine N-oxide cations are discussed. The determined pK_a values of the protonated 2-halo-4-nitropicoline N-oxides are compared with the previously determined equilibrium constants of the cationic acids conjugated with the mono- and disubstituted pyridine N-oxides in acetonitrile. Further, based on the pK_a values of the protonated 2-halo-4-nitropicoline N-oxides in acetonitrile, supplemented with correlations between pK_a’s of the protonated mono- and disubstituted pyridine N-oxides in acetonitrile and water, the pK_a's of the acids conjugated with the trisubstituted N-oxides studied in aqueous solutions have been estimated. Moreover, it has been concluded that the cationic homoconjugation constants cannot be determined by potentiometric titration in acetonitrile solutions of the 2-halo-4-nitropicoline N-oxide systems. Full article

140 KiB

Open AccessArticle

X-ray Crystallography at 170 K of Racemic 2,2'-Dimethoxy-9,9'-biacridine and 1H NMR Study of 2,2'-Diacetoxy-9,9'-biacridine

by Gérard Boyer, Tuan Lormier, Jean-Pierre Galy, Antonio L. Llamas-Saiz, Concepción Foces- Foces, Marta Fierros, José Elguero and Albert Virgili

Molecules 1999, 4(4), 104-121; https://doi.org/10.3390/40400104 - 16 Apr 1999

Cited by 7 | Viewed by 10548

Abstract

Three derivatives of 9,9'-biacridine, 2,2'-dihydroxy, 2,2'-dimethoxy and 2,2'-diacetoxy have been prepared. The crystal structure of racemic 2,2'-dimethoxy-9,9'-biacridine CHCl₃ 1:1 complex has been determined and shows an almost perpendicular conformation of both acridine rings. ¹H NMR experiments using the diacetoxy derivative and [...] Read more.

Three derivatives of 9,9'-biacridine, 2,2'-dihydroxy, 2,2'-dimethoxy and 2,2'-diacetoxy have been prepared. The crystal structure of racemic 2,2'-dimethoxy-9,9'-biacridine CHCl₃ 1:1 complex has been determined and shows an almost perpendicular conformation of both acridine rings. ¹H NMR experiments using the diacetoxy derivative and both Eu(tfc)₃ and R-Pirkle's alcohol show the splitting of some signals characteristic of a racemic compound. Full article

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Molecules, Volume 4, Issue 4 (April 1999) – 6 articles , Pages 81-121, Articles M92-M94

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