01/2008:0095 corrected 6.0

LINSEED

Lini semen

DEFINITION

Dried, ripe seeds of Linum usitatissimum L.

IDENTIFICATION

A. The linseed has a flattened, elongated ovoid shape. The testa is dark reddish-brown or yellow, smooth and shiny. The seeds are 4-6 mm long, 2-3 mm wide and 1.5-2 mm thick; one end is rounded and the other end forms an oblique point near which the hilum appears as a slight depression. When viewed with a lens, the surface of the seed-coat is seen to be minutely pitted. Inside the testa a narrow, whitish endosperm and an embryo composed of 2 large, flattened, yellowish and oily cotyledons are present; the radicle points towards the hilum.

B. Reduce to a powder (355) (2.9.12). The powder is greasy to the touch. Examine under a microscope using chloral hydrate solution R. The powder consists of fragments of the outer epidermal cells of the testa filled with mucillage ; collenchymatously thickened sub-epidermal layer seen in surface view as rounded cells with distinct triangular intercellular spaces often attached to the sclerenchymatous layer composed of elongated cells, some with strongly thickened and pitted walls; thin-walled pitted cells of the hyaline layer often remaining attached to the elongated sclereids and crossing them at approximately right angles; pigmented cells of the inner epidermis of the testa composed of moderately thickened polygonal cells filled with orange-brown pigment; parenchyma of the endosperm and cotyledons containing aleurone grains and fatty oil.

TESTS

Foreign matter (2.8.2): maximum 10 per cent of seeds with adull coat and maximum 1.5 per cent of other foreign matter.

Swelling index (2.8.4): minimum 4.

Cadmium (2.4.27): maximum 0.5 ppm.

Loss on drying (2.2.32): maximum 8.0 per cent, determined on1.000 g of the powdered drug (355) (2.9.12) by drying in an oven at 105 °C for 2 h.

Total ash (2.4.16): maximum 5.0 per cent.