Table 1 Analytical data of isolated compound (Tuberosin; 5hydroxy 3,6,7,3'4' pentamethoxy flavone)

Melting point

271-72°C

TLC pattern

Solvent system: benzene:ethyl acetate (7:3)

RF value: 0.45

UV(MeOH)

(log ε): 255(4.26),

274 (4.18) and

346 nm (4.21)

IR (KBr) cm^-1

3480, 1664 and 1559

¹H NMR (CDCl₃)

δ 12.62 (1 H, s, O - H), 7.75 (2 H, m, 2' - H and 6' - H), 7.01 (1 H, d, J = 9.0 Hz, 5' - H), 6.51 (1 H, s, 8 - H), 3.98 (9 H, s, 3 × OCH₃), 3.93 (3 H, s, OCH₃) and 3.87 (3 H, s, OCH₃).

¹³C NMR

δ 158.7 (C - 2), 132.4 (C - 3), 178.8 (C - 4), 155.7 (C-5), 138.8 (C-6), 152.7 (C-7), 90.3 (C- 8), 151.5 (C-9), 106.6 (C-10), 122.9 (C-1'), 111.7 (C-2'), 148.9 (C-3'), 152.2 (C-4'), 111.6 (C-5'), 122.1 (C-6'), 60.7 (6-OCH₃), 56.1 (7-OCH₃), 60.1 (3-OCH₃), 56.2 (3' - OCH₃) and 55.9 (4' - OCH₃).