Bitter Apple, Colocynthis, Colocynth Pulp, Fructus Colocynthidis
Colocynth consists of the dried pulp of the fruits of Citrullus colocynthis Sch., an annual or perennial herb of the family Cucurbitaceae.
Supply of the drug is mainly derived from Syria, Cyprus, the Sudan arid North African countries.
The entire fruit is a globular berry, 5 to 8 cm in diameter and yellowish brown in colour. The peeled fruit is nearly white in colour and very light in density, externally marked by spiral flattish areas, each about 1 cm wide. A transverse cut through the fruit shows three large splits dividing the fruit in to three parts, each containing two groups of seeds near the periphery; the remaining space is filled with pithy parenchyma. Each fruit contains 200 to 300 flattened ovoid glabrous seeds, yellowish brown in colour 6 to 8 mm in length, with one end somewhat pointed where a small hilum is situated. Embryo consists of two large cotyledons containing fixed oil.
The pulp, freed from the seeds, occurs in broken pieces, white to pale yellowish white in colour and pithy in constitution. It has an intensely bitter taste and no odour.
Fig. 40: Colocynth. A, peeled fruit; B, transversely cut fruit, C, longitudinally cut fruit; D, seeds; E, epidermis and parenchyma of pericarp; f, sclerenchyma of outer part of pericarp; G, pithy part of pericarp. cots, cotyledons; e, epidermis; hi, hilum; ls, linear split; m, knife mark; s, seeds, t, testa (Reconstructed from Wallis).
The whole pulp consists of large flat, rounded and finely pitted parenchymatous cells with intercellular spaces. The walls are partly lignified. The cells of the epidermis of the epicarp, when present, are polygonal with their outer and radial walls thickened and cuticularised; large stomata occur at intervals. The major part of the epicarp is composed of many layers of thin-walled parenchyma followed by a layer of thick-walled sclerenchyma. The sclereids are heavily thickened towards the outer side but thin walled towards the inner side gradually merging into the parenchyma of the pithy pulp.
Colocynth contains cucurbitacin E or alpha elater:n (a glycoside), an amorphous alkaloid, amorphous resins and c1trullol (di-hydric alcohol).
Colocynth is used as a hydragogue cathartic because of its gastrointestinal irritant properties and most powerful purgative action.