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Acanthus Ebracteatus Herb is the dried whole plants of Acanthus ebracteatus Vahl (Family Acanthaceae), Herbarium Specimen Number: DMSC 5252, Crude Drug Number: DMSc 1202.

Constituents Acanthus Ebracteatus Herb contains phenolic glycosides (e.g., verbascoside), flavone glycosides, heteropolysaccharides, etc.

Description of the plant (Figs. 1a, 1b) Shrub-up to 2.5 m tall; stem terete, lenticellate, glabrous and glossy, succulent, purplish brown to brown, frequently  with stipule-like spines at nodes; prop roots usually present; bark thin, thick at lower part. Leaves simple, opposite, oblong to obovate-oblong, 5 to 13 cm long, 3 to 5 cm wide, apex truncate to obtuse, slightly mucronate, base cuneate, margin 3- or 4-toothed or irregularly pinnatifid, subcoriaceous to coriaceous, upper surface green to dark green, glossy, lower surface pale green, glabrous, secondary veins 3 to 8 on each side of midvein, spreading to spinose teeth margin; petiole1 to 4 cm long. Inflorescence terminal, up to 20 cm long; bract brown, broadly ovate, 6 to 7 mm long, 4 to 5 mm wide, sometimes caducous; bracteole caducous; calyx light green, 4-lobed, broadly ovate, 0.8 to 1.2 cm long, 5 to 9 mm wide, lateral lobes elliptic, about 1 cm long, about 4 mm wide; corolla white, rarely with purplish tint, 1.5 to 2 cm long, tube 5 to 8 mm long, about 4 mm wide, lip oblong, 1 to 1.5 cm long, 0.5 to 1 cm wide, apex emarginate, pubescent inside; stamens 4, subequal, epipetalous; filament cream or pale brown, about 8 mm long; anther theca oblong, 3 to 5 mm long, with a line of trichomes on both sides of suture; ovary superior, ovate, about 2 mm long, 2-loculed, each locule with 2 ovules, style white, about 1 cm long, bifid. Fruit a capsule, elliptic or oblong, 1 to 1.7 cm long, 0.5 to 1.2 cm wide, glabrous. Seeds whitish to pale brown, 2(‒4), orbicular to elliptic, about 8 mm
long, about 6 mm wide, flattened, rugulose.

Description Odour, characteristic; taste, slightly salty-astringent.
       Macroscopical (Fig. 1a) Whole plant occurs as a mixture of broken, crisp, mainly greenish brown leaves with spinose teeth margin; terete and lenticellate stems with spines at node; elliptic to oblong capsules; some with roots and inflorescences. Unbroken leaves may also be included.
       Microscopical (Figs. 2a, 2b, 2c, 2d, 2e, 2f) Transverse sections of the leaf through midrib and lamina show upper epidermis, hypodermis, mesophyll, vascular bundle, and lower epidermis. Upper epidermis: a layer of small rectangular cells covered with thick cuticle; salt glands with 6- to 8-celled head and unicellular stalk. Hypodermis: 1 to 2 layers of large and thin-walled cells. Mesophyll: palisade cells, 2 or 3 layers and cylindrical; spongy cells, irregular-shaped and loosely arranged; collenchyma, angular and several layers; parenchyma, thin-walled and round; both collenchyma and parenchyma found in the
upper and lower parts of midrib. Vascular bundle: xylem in the upper part; and phloem in the lower part. Lower epidermis: a layer of small rectangular cells covered with thick cuticle; salt glands with 6- to 8-celled head and unicellular stalk; non-glandular trichome, multicellular uniseriate, rarely.

       In surface view, upper epidermis of the lamina shows slightly wavy-walled cells and salt gland; lower epidermis illustrates wavy-walled cells, diacytic stomata, salt gland, and rarely non-glandular trichomes.
       Transverse section of the stem shows cork layer, cortex, vascular tissue, and pith. Cork: several layers of rectangular cells. Cortex: several layers of thin-walled parenchyma cells with air space. Vascular tissue: phloem and xylem. Pith: various sizes and shapes of parenchyma cells, some containing sclereids.
       Transverse section of the root shows periderm, cortex, vascular tissue, and pith. Periderm: several layers of small rectangular cork cells. Cortex: several layers of thin-walled aerenchyma cells with air space. Vascular tissue: phloem and xylem; phloem, thin-walled parenchyma cells; xylem, vessels, xylem parenchyma, fibres, and xylem rays. Pith: parenchyma cells.
       Transverse section of the flower exhibits calyx, corolla tube and ovary.
       Acanthus Ebracteatus Herb in powder possesses the diagnostic microscopical characters of the unground drug. Elongated sclereids, salt glands and diacytic stomata are characteristic.

Packaging and storage Acanthus Ebracteatus Herb shall be kept in well-closed containers, protected from light, and stored in a dry place.

Identification
       A. Warm 1 g of the sample, in fine powder, with 20 mL of water on a water-bath for 30 minutes and filter (solution 1). To 2 mL of solution 1, examine under ultraviolet light (366 nm): a blue fluorescence is observed.
       B. To 2 mL of solution 1, add 1 drop of iron(III) chloride TS: a dark brown flocculent precipitate is produced.
       C. Carry out the test as described in the “Thin-Layer Chromatography” (Appendix 3.1), using silica gel GF254 as the coating substance and a mixture of 70 volumes of ethyl acetate, 10 volumes of methanol, 10 volumes of water, and 10 volumes of formic acid as the mobile phase and allowing the solvent front to ascend 8 cm above the line of application. Apply separately to the plate as bands of 10 mm, 5 µL of solution (A) and 2 µL of solution (B). Prepare solution (A) by sonicating 2 g of the sample, in fine powder, with 20 mL of methanol for 10 minutes and filter. Evaporate the filtrate under reduced pressure to dryness and dissolve the residue in 5 mL of methanol. For solution (B) dissolve 1 mg of verbascoside in 5 mL of methanol. After removal of the plate, allow it to dry in air and examine the plate under ultraviolet light (254 nm), marking the quenching bands. The chromatogram obtained from solution (A) shows a quenching band (hR_f value 74 to 76) corresponding to the verbascoside band from solution (B); several other quenching bands are also observed. Subsequently examine the plate under ultraviolet light (366 nm) through the cut-off filter, the band corresponding to verbascoside shows blue fluorescence. Several other blue fluorescent bands are also observed. Spray the plate with anisaldehyde TS and heat at 105º for 5 minutes; the band due to verbascoside is greenish brown. Other two brown, two grey and two purple bands are observed (Fig. 3).

Loss on drying Not more than 9.0 percent w/w after drying at 105º to constant weight (Appendix 4.15).

Foreign matter Not more than 2.0 percent w/w (Appendix 7.2).

Acid-insoluble ash Not more than 1.0 percent w/w (Appendix 7.6).

Total ash Not more than 14.0 percent w/w (Appendix 7.7).

Ethanol-soluble extractive Not less than 2.5 per cent w/w (Appendix 7.12).

Water-soluble extractive Not less than 17.0 per cent w/w (Appendix 7.12).