C. Galeffi

Research on African medicinal plants—II: Hypoxoside, a new glycoside of uncommon structure from hypoxis obtusa busch☆

Abstract A new glycoside, hypoxoside, was isolated from rhizome of Hypoxis obtusa , a plant used in Mozambique in native medicine for the treatment of urinary diseases. The structure 1 of a diglycoside of 1-(3′,4′-dihydroxyphenyl)-5-(3″,4″-dihydroxyphenyl)-1-penten-4-yne was attributed to hypoxoside on the basis of physico-chemical determinations and chemical behaviour.

Plant screening by chemical and chromatographic procedures under field conditions

Abstract The plant kingdom constitutes an invaluable source of new chemical products which may be important due to their biological properties and in particular because of their potential use in medicine. In many countries, mainly in the Tropics, systematic surveys of plants are currently in progress. It is therefore important to have a simple and universal method available for preliminary chemical screening of plants under field conditions. The procedure suggested here is based on the identification in raw plant extracts of some chemical groups of substances (alkaloids, quinones, saponins, polyphenols, anthranoids) by precipitation and colour reactions. To obtain more accurate results, a second stage, based on thin-layer chromatographic separation of extracts of plant material, can be applied. Solvent systems, specific spray reagents and reference substances are proposed. A number of groups of products, including flavonoids, coumarins, cardenolides and steroids can be rapidly identified in plants by this method.

Research on african medicinal plants—IV: Boonein, A new C-9 terpenoid lactone from alstonia boonei: A possible precursor in the indole alkaloid biogenesis

Abstract From the bark of Alstonia boonei De Wild (Apocynaceac) a new monoterpenoid δ-lactone 1, named boonein, was isolated. The structure was established by chemical and spectroscopical methods and by X-ray analysis.

Biological activities of the plant-derived bisindole voacamine with reference to malaria.

The in vivo antiplasmodial activity of voacamine was assessed in a 4‐day test. It was shown to exhibit in vivo activity with 25.4% and 43.4% inhibition of parasitaemia with 2.5 and 10 mg/kg, respectively. In synchronized cultures, it was found to act on trophozoite and schizont stages of Plasmodium falciparum. Using the FMC29 strain of Plasmodium falciparum as parasite and the isobologram curve as a method to assess interaction in drug combination, it was shown to lack any chloroquine‐enhancing activity and its in vitro antiplasmodial effect was not potentiated by the chemosensitizer malagashanine. Copyright

Research on african medicinal plants - X: Glucosides of Hypoxis nyasica bak. the structure of nyasoside, a new glucoside biologically related to hypoxoside

Abstract From rhizome of Hypoxis nyasica two diglucosides were isolated: hypoxoside, (1), and a new one, the 0,0-β,β-di-D-glu- copyranoside of 1-(4 - hydroxyphenyl)-3-(4 - hydroxyphenyl)-1,4-pen- tadiene, (2), named nyasoside.

Two prenylated isoflavanones from Millettia pervilleana

Abstract From the root bark of Millettia pervilleana , which showed high cytotoxic activity, two prenylated isoflavanones were isolated. Their structures were determined by means of chemical and spectroscopic properties to be (3 R )-2′,7-dihydroxy-3′,4′-dimethoxy-5′- α , α -dimethylallylisoflavanone, named pervilleanone, and its 3′- O -demethyl derivative.

Benzylbenzoate and norlignan glucosides from Curculigo pilosa: structural analysis and in vitro vascular activity

From the rhizomes of Curculigo pilosa, two benzylbenzoate diglucosides, piloside A and piloside B, and a glucosyl-fused norlignan, pilosidine, previously obtained only as the tetra-O-methyl derivative, were isolated. Pilosidine showed facilitating effect on adrenaline evoked contractions in rabbit aorta isolated preparations.

Cyclohexanols of Halleria lucida

Abstract From the stems of Halleria lucida a new 1,4-yclohexandiol, a tranS -1-(2′-hydroxyethyl)cyclohexan-1,4-diol named isorengyol, together with the known cis isomer rengyol, was isolated. The leaves of the same plant contain acteoside, rutin, luteolin-5- O -glucoside and a 4-hydroxy-4-(2′-hydroxyethyl)cyclohexanone, of which the hemiketalic tautomer has recently been described.

p-Hydroxybenzaldehyde as a major constituent of the epicuticular wax of seedling Sorghum bicolor

Abstract p-Hydroxybenzaldehyde is present in concentrations up to 30% in the wax of Sorghum bicolor seedlings. It is highly deterrent to locusts, reducing their normal feeding by 90%.

Alkaloids of Strychnos rubiginosa

Abstract A new corynantheine-type alkaloid, strychnorubigine, was identified from root bark of Strychnos rubiginosa D.C. 11-Methoxydiaboline and normacusine B were also isolated and the 13 C NMR spectral data of their O -acetyl derivatives are reported.