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  • Developmental patterns of phenylpropylamino alkaloids accumulation in khat (Catha edulis, Forsk.).

Developmental patterns of phenylpropylamino alkaloids accumulation in khat (Catha edulis, Forsk.).

Journal of ethnopharmacology (2007-10-12)
Raz Krizevski, Nativ Dudai, Einat Bar, Efraim Lewinsohn
ABSTRACT

Khat (Catha edulis Forsk., Celastraceae) is a perennial shrub that was introduced to Israel by Yemenite immigrants. Khat young leaves are chewed as a stimulant. The main stimulating active principles in this plant are the phenylpropylamino alkaloids (-)-cathinone [(S)-alpha-aminopropiophenone], (+)-cathine [(+)-norpseudoephedrine] and (-)-norephedrine. A novel GC-MS analysis method for the quantitative determination of phenylpropylamino alkaloids and their putative precursor 1-phenyl-1,2-propanedione in khat leaves was developed. We found a marked diversity in the phenylpropylamino alkaloids content and composition in 9 different accessions originated in seedlings and in the commercial cultivar "Mahanaim". The highest 1-phenyl-1,2-propanedione and (-)-cathinone levels occur in young leaves, the part traditionally chewed for its psycho-stimulating properties. Older leaves lack (-)-cathinone but contain the less active (+)-cathine and (-)-norephedrine. Young stems and flowers also contain 1-phenyl-1,2-propanedione, (-)-cathinone, (+)-cathine and (-)-norephedrine. We report the presence of a (-)-cathinone reductase in khat leaves capable of reducing (-)-cathinone to (+)-cathine in the presence of NADPH. We propose that (-)-cathinone is a biosynthetic precursor of (+)-cathine and (-)-norephedrine in khat leaves.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
(1S,2R)-(+)-Norephedrine, 98%
Sigma-Aldrich
Cathine hydrochloride
Sigma-Aldrich
DL-Norephedrine hydrochloride, ≥99%
Supelco
(+)-Norpseudoephedrine hydrochloride solution, 100 μg/mL in methanol (as free base), ampule of 1 mL, certified reference material, Cerilliant®
Supelco
(±)-Phenylpropanolamine hydrochloride solution, 1.0 mg/mL in methanol (as free base), ampule of 1 mL, certified reference material, Cerilliant®