Ana M. Simonet

Potential allelochemicals from Sambucus nigra

Twenty-four aromatic metabolites belonging to cyanogenins, lignans, flavonoids, and phenolic glycosides were obtained from Sambucus nigra. Structures were determined on the basis of their spectroscopic features. Two compounds have been isolated and identified as (2S)-2-O-beta-D-glucopyranosyl-2-hydroxyphenylacetic acid and benzyl 2-O-beta-D-glucopyranosyl-2,6-dihydroxybenzoate. All the compounds have been assayed on dicotyledons Lactuca sativa (lettuce) and Raphanus sativus (radish) and monocotyledon Allium cepa (onion) to test their stimulatory or inhibitory effects on seed germination and radicle elongation. Cyanogenins have a mainly inhibiting effect while lignans stimulate the growth. Some compounds show different effects on dicotyledons and monocotyledons.

Bioactive steroids and triterpenes from Melilotus messanensis and their allelopathic potential

The aerial parts of Melilotus messanensis (sweet clover) afforded, from moderately and polar bioactive fractions, 11 triterpenes and five steroids. A series of aqueous solutions at 10−4–10−9 M of five steroids and nine triterpenes was monitored to test their effects on germination and growth of the monocots Hordeum vulgare and Allium cepa, and the dicots Lactuca sativa (var. nigra and var. romana) and Lycopersicon esculentum. An important stimulatory effect on H. vulgare germination (between 40% and 80% for almost all tested compounds) was observed. Some considerations about the ecological role of triterpenes on M. messanensis are made. In addition to known lupane triterpenes (platanic acid and 3β,28,30-lup-20(29)-enetriol), oleanane triterpenes (soyasapogenol B, soyasapogenol G, and messagenolide), a gammacerane triterpene (gammacer-16-en-3-one), five new lupane triterpenes (messagenic acids A–E: (27-cis-4-hydroxycinnamoyloxy)-betulinic acid; 27-(trans-4-hydroxycinnamoyloxy)betulinic acid; 20(S)-3β-hydroxy-29-oxolupan-28-oic acid; 3β,30-dihydroxylup-20(29)-en-28-oic acid; and 3β,20-dihydroxylup-18(19)-en-28-oic acid, respectively), and sterols (β-sitosterol, ergosterol peroxide, 7α-hydroxysitosterol, 7β-hydroxysitosterol, and 7-oxositosterol) were isolated and chemically characterized. Their structures and stereochemistry were elucidated by spectroscopic methods (one- and two-dimensional 1H and 13C NMR, IR, MS).

Potential allelopathic lupane triterpenes from bioactive fractions of Melilotus messanensis

Abstract The aerial parts of Melilotus messanenis (sweet clover) afforded, from the medium polar bioactive fractions, in addition to the known lupane triterpenes lupeol, betulin, betulin aldehyde and betulinic acid, the new norlupane messagenin (30-norlupane-3β,28-diol-20-one) which have been tested as allelochemicals. Structures and their stereochemistries were elucidated by spectral methods and chemical transformations. Messagenin has been synthesized from betulinic acid. The effect of a series of aqueous solutions at 10 −4 -10 −9 M of eight natural and synthetic lupane derivatives were tested for their effects on the germination and growth of the dicotyledon species Lactuca sativa and Lepidium sativum and the monocotyledon species Hordeum vulgare and Triticum aestivum . All eight lupane triterpenes possess potential allelopathic activity in particular over dicotyledon species and they are likely to be significantly involved in the allelopathic action of Melilotus messanensis .

Brevione A. The first member of a novel family of bioactive spiroditerpenoids isolated from Penicillium brevicompactum Dierckx

Abstract (+)-Brevione A, the first member of a novel family of bioactive spiroditerpenoids, a potential allelopathic agent, has been isolated from the ethyl acetate active fractions of the aqueous acetone extracts of semi-solid fermented Penicillium brevicompactum Dierckx. The structure displays the novel spiroditerpenoid skeleton of breviane. The structure elucidation of brevione A was performed by homo- and hetero-nuclear 2D NMR spectral data. On the basis of combined studies of the theoretical conformations and NOEDIFF data, its relative stereochemistry is proposed.

Flavonoids from Pinus sylvestris needles and their variation in trees of different origin grown for nearly a century at the same area

Abstract Flavonoids in needles of Scots pine planted in 1912–1914 in Poland from seeds originating from different parts of Europe, were isolated, chemically characterised and analysed by HPLC. It was shown that flavonoid profiles were similar in all tested populations and were different from those previously reported for Scots pine seedlings. They included taxifolin, taxifolin 3′- O -glucoside, quercetin as well as quercetin 3- O -glucoside and 3′- O -glucoside. The quercetin 3- O -glucoside could be found only in a trace amount in all samples and quercetin 3′- O -glucoside appeared in all samples regardless their origin. The relative concentration of taxifolin 3′- O -glucoside, quercetin, taxifolin and total flavonoids showed dependence on the origin of seeds; needles from high latitude populations contained smaller amounts of these compounds. Presented data clearly indicate that Scots pine contain glycosidases specific for glycosylation at C-3′ rather than at C-3. Besides, they indicate that long lasting influence of similar environmental factors is not able to change genetic regulatory systems responsible for flavonoid biosynthesis.

Bioactive polar triterpenoids from Melilotus messanensis

Abstract In addition to the known 3-oxoplatanic acid, melilotigenin and soyasapogenol E, two new lupane (messagenic acids F, G), two nor-lupane triterpenic acids (messagenic acids H, I), and three new oleanane triterpenes (melilotigenins B-D) were isolated and characterized from the polar bioactive fractions of Melilotus messanensis. The synthesis of messagenic acids D, F, G, betulonic acid and 3,29-dioxolup-20(30)-en-28-oic acid has been carried out from betulinic acid. These compounds exhibited clear selectivity (parameters and species) over germination and growth of monocotyledon species with average of inhibition of −50% on the germination of Hordeum vulgare, and average of stimulation of 30% on the germination of Allium cepa.

Saponins and polar compounds from Trifolium resupinatum

Abstract In addition to the known soyasaponin I, 3- O -[α- l -rhamnopyranosyl(1→2)-β- d -galactopyranosyl(1→2-β- d -glucuronopyranosyl]-22- O -[β- d -glucuronopyranosyl(1→2)-β- d -glucopyranosyl]soyasapogenol B, soyasaponin II, 3- O -β- d -glucopyranosyl sitosterol, 3- O -β- d -glucopyranosyl stigmasterol and 3- O -α- l -arabinopyranosyl-(1→6)-β- d -glucopyranosyl]oct-1-ene-3-ol, the new saponin, 3- O -α- l -rhamnopyranosyl(1→2)-β- d -galactopyranosyl(1→2)-β- d -glucuronopyranosyl]-22- O -β- d -glucopyranosyl soyasapogenol B ( 2 ) was isolated and characterised from the seed saponins fraction of Trifolium resupinatum . The structural determination is based on spectroscopic methods (including DQF-COSY, HETCOR, TOCSY, ROESY and NOEs experiments).

Phytotoxic steroidal saponins from Agave offoyana leaves

A bioassay-guided fractionation of Agave offoyana leaves led to the isolation of five steroidal saponins (1-5) along with six known saponins (6-11). The compounds were identified as (25R)-spirost-5-en-2α,3β-diol-12-one 3-O-{α-l-rhamnopyranosyl-(1→3)-O-β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (1), (25R)-spirost-5-en-3β-ol-12-one 3-O-{α-l-rhamnopyranosyl-(1→3)-O-β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (2), (25R)-spirost-5-en-3β-ol-12-one 3-O-{β-d-xylopyranosyl-(1→3)-O-β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (3), (25R)-26-O-β-d-glucopyranosylfurost-5-en-3β,22α,26-triol-12-one 3-O-{α-l-rhamnopyranosyl-(1→3)-O-β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (4) and (25R)-26-O-β-d-glucopyranosylfurost-5-en-3β,22α,26-triol-12-one 3-O-{β-d-xylopyranosyl-(1→3)-O-β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (5) by comprehensive spectroscopic analysis, including one- and two-dimensional NMR techniques, mass spectrometry and chemical methods. The phytotoxicity of the isolated compounds on the standard target species Lactuca sativa was evaluated.

Bioactive steroidal saponins from Agave offoyana flowers

Bioguided studies of flowers of Agave offoyana allowed the isolation of five steroidal saponins never described previously, Magueyosides A-E (1-5), along with six known steroidal saponins (6-11). The structures of compounds were determined as (25R)-spirost-5-en-2α,3β-diol-12-one 3-O-{β-d-xylopyranosyl-(1→3)-O-β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (1), (25R)-spirost-5-en-2α,3β-diol-12-one 3-O-{β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (2), (25R)-spirost-5-en-2α,3β,12β-triol 3-O-{β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (3), (25R)-5α-spirostan-2α,3β-diol-12-one 3-O-{β-d-xylopyranosyl-(1→3)-O-β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (4), and (25R)-5α-spirostan-2α,3β-diol-9(11)-en-12-one 3-O-{β-d-xylopyranosyl-(1→3)-O-β-d-glucopyranosyl-(1→2)-O-[β-d-xylopyranosyl-(1→3)]-O-β-d-glucopyranosyl-(1→4)-O-β-d-galactopyranoside} (5), by comprehensive spectroscopic analysis, including one- and two-dimensional NMR techniques, mass spectrometry and chemical methods. The bioactivities of the isolated compounds on the standard target species Lactuca sativa were evaluated. A dose-dependent phytotoxicity and low dose stimulation were observed.

Cyanogenic Glycosides from Sambucus Nigra

Abstract A new cyanogenic glycoside, 2S-β-D-apio-D-furanosyl-(1→rightarrow2)-β-D-glucopyranosylmandelonitrile, has been isolated from the leaves of Sambucus nigra along with the already known sambunigrin, prunasin, holocalin and the acetyl derivative of the latter. The structures were elucidated by chemical and physical methods.