สารบัญ

        Purging Cassia Pulp is the aril of the ripe pod of Cassia fistula L. (Family Leguminosae), Herbarium Specimen Number: DMSC 5162, BKF 114900, Crude Drug Number: DMSc 1142

Constituents Purging Cassia Pulp contains anthraquinones (e.g., rhein and its glycosides). It also contains flavonoids, tannins, etc.

Description of the plant (Figs. 1a, 1b) Deciduous tree, up to 20 m tall; bark smooth, greenish grey when young, becoming rough and dark brown when mature. Leaves pinnately compound, 10 to 60 cm long; petiole 7 to 10 cm long; rachis 15 to 25 cm long; stipule small and caducous; leaflets opposite, 3- to 8-paired, ovate to ovate-oblong, 6 to 20 cm long, 3.5 to 9 cm wide, apex acute to acuminate, base cuneate, upper surface glabrous, lower surface silvery pubescent when young, becoming glabrous when mature. Inflorescence raceme, axillary, drooping, lax, many-flowered, 20 to 40(‒60) cm long; pedicel 1.5 to 5 cm long; bract about 1 cm long, caducous. Flower: sepals 5, ovate-elliptic, about 1 cm long, velutinous, reflexed at anthesis; petals 5, subequal, broadly ovate or obovate, 2 to 3.5 cm long, 1 to 2 cm wide, distinctly veined, short-clawed, yellow; stamens 10, 3 long, 4 short and 3 reduced forms, long stamens much curled and bearing large oblong anther, opening by apical and basal slits, short stamens with straight filaments, reduced stamens with minute anther; ovary stalked, velutinous, style velutinous, stigma small. Fruit pod, terete, 20 to 60 cm long, 1 to 2.5 cm wide, pendulous, indehiscent, blackish brown to black. Seeds numerous, elliptic, 7.5 to 9 mm long, 5 to 7 mm wide, flat, glossy brown, embedded in blackish pulp, separated by spongy septa.

Description Odour, characteristic; taste, unpleasantly sweet.

           Macroscopical (Fig. 1a) Sticky lump of pulp, dark brown to black.

          Microscopical [Note Even though the pulp (aril) is used as a crude drug, microscopical description of the young pod is provided here for better understanding of the entire structure enclosing the pulp and the seed within.] (Figs. 2a, 2b, 2c, 2d) Transverse section of the pod shows pericarp and seed. Pericarp, consisting of a rectangular epidermal layer (rarely with unicellular trichome), parenchyma cells some of which containing prismatic crystals, vascular bundles, and layers of elongated sclereids. Seed, containing aril and seed coat; aril, parenchyma cells, some of which containing rosette aggregate crystals; seed coat, covered with thick cuticle layer, layers of non-lignified macrosclereids and two layers of non-lignified lagenosclereids separated by layers of thick-walled parenchyma.

      Purging Cassia Pulp possesses the diagnostic microscopical characters of the aril of the drug. The parenchyma cells containing brownish to blackish granular mass is characteristic.

Contra-indication It is contra-indicated in patients with constipation from intestinal obstruction, diarrhoea, abdominal pain, nausea, and vomiting.

Warning

          1. Prolonged use should be avoided since it may result in laxative dependence.

          2. Pod shell and seeds should be removed from the pulp since they may cause vomiting.

Additional information

          1. Although in Thai traditional remedies the crude drug is usually addressed as “ฝักคูน (FAK KHUN)” which means a purging cassia pod, only the pulp after removal of shell and seeds [เนื้อในฝักคูน (KHUN, NUEA NAI FAK)] is used in the preparations. Therefore, it is chosen to be the title of this monograph.

          2. To obtain its maximum benefit, it is recommended that the pulp be freshly taken from the purging cassia pod.

Packaging and storage Purging Cassia Pulp shall be kept in well-closed containers, protected from light, and stored in a dry place.

Identification

          A. To 3 g of the sample, add 25 mL of 2 M hydrochloric acid, heat on a water-bath for 30 minutes, and immediately filter through a plug of cotton wool. Allow the filtrate to cool and shake with 20 mL of dichloromethane. Collect the dichloromethane layer and shake with 10 mL of ammonia TS: the aqueous layer becomes red.

          B. 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 100 volumes of ethyl acetate, 17 volumes of methanol and 3 volumes of water as the mobile phase and allowing the solvent front to ascend 10 cm above the line of application. Apply separately to the plate, 4 μL each of the following solutions. Prepare solution (A) by refluxing 5 g of the sample with 50 mL of chloroform on a water-bath for 30 minutes, filtering and evaporating the filtrate to dryness. Dissolve the residue in 1.0 mL of chloroform. For solution (B) dissolve 3 mg of rhein in 1 mL of methanol. After removal of the plate, allow it to dry in air and examine under daylight, locating the spots. The chromatogram obtained from solution (A) shows a yellow spot corresponding to the rhein spot (hR_f value 49 to 52) from solution (B). Subsequently examine under ultraviolet light (254 nm), marking the quenching spots. The chromatogram obtained from solution (A) shows a quenching spot corresponding to the rhein spot from solution (B), and other two quenching spots of the lower hR_f values. Examine the plate under ultraviolet light (366 nm); the spot due to rhein is a brownish purple; one blue fluorescent spot is also observed. Spray the plate with a 10 per cent w/v solution of potassium hydroxide in ethanol; the spot corresponding to rhein is reddish pink (Table 1); see also Fig. 3.

Table 1 hR_f Values of Components in Chloroform Extract of the Aril of the Ripe Pods of Cassia fistula L.

       *rhein

Loss on drying Not more than 14.0 per cent w/w after drying at 105° to constant weight (Appendix 4.15).

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

Total ash Not more than 4.0 per cent w/w (Appendix 7.7).

Ethanol-soluble extractive Not less than 66.0 per cent w/w (Appendix 7.12).

Water-soluble extractive Not less than 67.0 per cent w/w (Appendix 7.12).

Dose 3 to 10 g at bed time.