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          Red Sandalwood is the dried heartwood of Pterocarpus santalinus L. f. (Family Fabaceae), Herbarium Specimen Number:  BKF 170463, Crude Drug Number:  DMSc 0933. 

Constituents  Red Sandalwood contains red pigments consisting mainly of santalin A and santalin B.  It also contains isoflavones, a small amount of volatile oil, triterpenes, sterols, etc.

Description of the plant  (Figs. 1a, 1b)  Tree up to 15 m tall; deciduous; bark deeply cracked into vertical and horizontal rectangular plates, blackish brown. Leaves mos tly trifoliate, rarely 4 or 5, alternate, 10 to 18 cm long; petiole swollen at base; leaflet broadly elliptic to ovate, 7 to 10 cm long, 3.5 to 5.5 cm wide, apex round or deeply notched, base round or slightly cordate, margin entire, blade leathery, shiny. Inflorescence axillary or terminal, raceme or panicle; bract and bracteole small, often caducous. Flower yellowish, 1.6 to 2 cm long; petals 5, papilionaceous; stamens 10, subdiadelphous; ovary superior, shortly stalked, 2-ovuled. Fruit samara, flat, obliquely rounded, broadly hardened winged around margin, beaked, 3.5 to 5 cm in diameter. Seeds 2, smooth, reddish brown.

Description  Odour, aromatic; taste, slightly astringent.

          Macroscopical  (Fig. 1a)  Irregular pieces of woody segment, dense, hard and heavy,  but readily split. Dark red to blackish red.  Transversely cut surface showing ring zones. Longitudinally cut surface showing alternating dark and light zones.

          Microscopical  (Figs. 2a, 2b, 2c, 2d, 2e)  Transverse section of the heartwood shows vessel, xylem parenchyma, xylem ray, and fibre.  Vessel, large, thick-walled, scattered, solitary or small cluster, some containing red resin.  Xylem parenchyma, oval, thick-walled, band paratracheal.  Xylem ray, mostly 1 row.  Fibre, thick-walled.

          Tangential and radial longitudinal sections of the heartwood show vessel, xylem parenchyma, xylem ray, and fibre.  Vessel, large, with bordered-pitted and simple perforation plate, some of which contain red resin.  Axial parenchyma, rectangular, thick-walled, some of which contain prismatic crystals of calcium oxalate.  Xylem ray; in tangential longitudinal view, mostly uniseriate, oval; in radial longitudinal view, rectangular, perpendicular to other adjacent cells.  Fibre, thick-walled, simple pitted.

          Red Sandalwood in powder possesses the diagnostic microscopical characters of the unground drug.

Storage  Red Sandalwood shall be stored in a dry place, protected from light.

Identification

          A. Reflux 1.2 g of the sample, in powder, with 30 mL of methanol for 30 minutes and filter (solution 1).  Evaporate 2 mL of solution 1 to dryness.  Dissolve the residue in 1 mL of acetic anhydride, slowly add a few drops of sulfuric acid and mix:  a deep brownish red colour develops.

          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 80 volumes of hexane and 20 volumes of ethyl acetate as the mobile phase.  Apply to the plate, 5 µL of the test solution prepared by evaporating about 20 mL of solution 1 to dryness and dissolving the residue  in 1 mL of methanol.  After removal of the plate, allow it to dry in air and examine under ultraviolet light (254 nm), marking the quenching spots. Subsequently examine the plate under ultraviolet light (366 nm) through the cut-off filter; several blue fluorescent spots are observed.  Spray the plate with anisaldehyde TS and heat at 110° for 10 minutes; several spots of different colours appear (Table 1); see also Fig. 3.

Table 1 hR_f Values of Components in Methanolic Extract of the Heartwood of Pterocarpus santalinus L. f.

Loss on drying  Not more than 8.0 per cent w/w after drying at 105° for 5 hours (Appendix 4.15).

Foreign matter  Not more than 0.5 per cent w/w (Appendix 7.2).

Total ash  Not more than 1.0 per cent w/w (Appendix 7.7).

Ethanol-soluble extractive  Not less than 12.0 per cent w/w (Appendix 7.12).

Water-soluble extractive  Not less than 1.0 per cent w/w (Appendix 7.12).

Dose  3 to 5 g a day.