Imidazole alkaloids from maca 

Extraction and Isolation.

The air-dried roots ( 10 kg) of

L. meyenii were washed with H2O and then extracted with

three changes of 100% EtOH. After removal of solvent, the

resultant extract (2 kg) was dissolved in 10 L of MeOH,

followed by adding 7 L of 1 N HCl solution slowly with stirring,

and allowed to stand for 4 h. The acidic MeOH-H2O solvent

was separated from the precipitate, and the process was

repeated twice. After removal of solvent, the combined aqueous

phase was extracted with CH2Cl2 (3 _ 4 L). The CH2Cl2 layers

were combined and evaporated to dryness to afford extract AE

(42 g). The remaining aqueous phase was adjusted to pH )

12 with 5 N NaOH solution and then extracted with CH2Cl2

(3 _ 3 L) to afford extract BE (10 g). The partial extract AE

(25 g) was absorbed and chromatographed on a Diaion HP-

20MG column (i.d. 8 cm, 60 cm) and eluted with 10% MeOH

in water, 40% MeOH in water plus 0.5% HOAc, MeOH, and

acetone to yield fractions A1, A2, A3, and A4, respectively.

After development using BuOH-AcOH-H2O (5:1:4) as a

solvent system, the TLC plate (silica gel) was dipped into

Dragendorff’s reagent solution. The alkaloid-positive spots

were mostly found in fraction A2, which was subfractionationed

over a normal-phase silica gel column using solvent

systems CH2Cl2-MeOH-AcOH (20:1:0.1-9:1:0.1) to give seven

fractions, B1-B7. Subfraction B5 was fractionationed over an

Al2O3 (acid type) column eluted with CH2Cl2-MeOH-H2O (20:

1:0.1-9:1:0.1) mixtures to afford a crude alkaloid fraction,

which was further purified by a combination of normal-phase

column chromatography and preparative HPLC (silica gel-60

Å) to yield compounds 1 (13 mg) and 2 (10 mg). Compounds 1

and 2 were crystallized to afford white needles in acetone and

white plates in 90% acetone-MeOH, respectively.