MATERIALS AND METHODS Extraction of Johnson Grass. Johnson grass rhizomes were obtained from a field at Stoneville, MS. Excess soil and debris were removed from the rhizomes (1 kg) by rinsing under cold running water. They were chopped and extracted (1 kg) with methanol under reflux for 2 h. The methanol was removed under vacuum to give 40 g (4%) dry extractables.

Fractionation of the Methanol Extract (See Figure 1). The methanol extract of rhizomes was chromato-graphed on a silica gel column (l= 150 cm, id= 5 cm) by using the solvents benzene (1 L), benzene-ethyl acetate, 5: 5 (v/v, 1 L), and chloroform-methanol-water, 65: 35: 20 (v/v/v, 1 L). The eluates from the second and third solvents were reduced to dryness and taken up with methanol, the second was separated on a cellulose column (l= 150 cm, id= 5 cm) by using 10% AcOH and the third by DCC (Droplet counter current apparatus, Tokyo Rikakikai, Toyama-cho, Kanda Chiyoda-ku, Tokyo, Japan) by using the upper phase of a solution of chloroform-methanol-propanol-water (5: 6: 1: 4 v/v) as the stationary phase and the lower phase of the solvent mixture as the moving phase. The eluates were collected in 10-mL fractions and monitored by TLC on silica gel plates.