ANNEXE IV: Composition du PBS
- Chlorure de sodium...........................7,65 g
- Phosphate disodique............................. 0,72 g
- Phosphate monosodique...................... 0,21 g
- Eau distillée qsp ............................1000 ml
ANNEXE V : Composition des colorants GRAM
Formule théorique pour 1l :
- Solution de cristal violet oxalate :
Cristal violet..................................20 g
Alcool éthylique dénaturé...............200
ml
Oxalate d'ammonium.........................8 g
Eau
déminéralisée.........................800 ml
- Lugol-PVP stabilisé :
Iode ............................................13 g
Iodure de potassium..........................20 g
PVP (polyvinyle-pyrrolidone)............100 g
Eau déminéralisée.......................1000
ml
- Décolorant :
Alcool éthylique dénaturé...............500
ml
Acétone....................................500 ml
- Solution de safranine :
Safranine......................................2,5 g
Alcool éthylique dénaturé...............100
ml
Eau
déminéralisée.........................900 ml
SUMMARY
A toxic activity was found in the extract of Pechia
madagascariensis (APOCYNACEAE) leaves.
A partially purified extract was obtained from cold
hydroethanolic crude extract by a purification procedure including treatment by
heat, a dialysis and a fractionation by ethyl acetate. The toxin yield was
about 4.86%.
The active principles are thermostable, soluble in polar
solvents such as water or ethanol, insoluble in the organic solvents as ethyl
acetate and precipitable by heavy metal salts like neutral lead acetate. They
taste bitter and their molecular weight are under 6000-8000 Da.
A phytochemical screening performed on partially purified
extract revealed the presence of alcaloïdes and steroids.
The crude extract (EB) injected in mouse by intraperitoneal
route caused symptoms suggesting an attack to the central nervous system. LD50
(24 h) is estimated between 120.78 and 128.5 mg/kg.
The active principles caused the lysis of sheep erythrocyte at
concentrations higher than or equal to 0.5 mg/ml.
The EB is toxic on cold blood animals ; LC50 (24 h) was
estimated 0.88 mg/ml for frog tadpoles, and 0.41 mg/ml for fish alevins, and
0.34 mg/ml for mosquito larvae.
In plants, EB inhibited the germinations of various seeds and
the growth of seedlings of rice (Monocotyledon) and of pea (Dicotyledon). The
growth of pea axillary bud was stimulated by crude and purified extracts.
In microorganisms, crude extract at 200 mg/ml had no toxic
activities on the tested germs.
Key words; Pechia
madagascariensis, APOCYNACEAE, LD50, LC50, toxic, inhibition, germination,
hemolysis
Nom : BOTOSOA
Prénom : Jean Ariel
Titre du mémoire : Purification et
caractérisation chimique et biologique partielle des principes actifs de
feuilles de Pechia madagascariensis (APOCYNACEAE)
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