F. Ascaridole (Synonym Ascarisin)
Chemical Structure 1, 4-Peroxido-p-menthene-2. It is an organic peroxide which constitutes 60-80% of oil of chenopodium. It is the only naturally occurring terpenoid peroxide.
Occurrence Ascaridiole is the major constituent (65-70%) in the chenopodium oil, i.e., a volatile oil, obtained by the steam distillation from the fresh flowing and fruiting plants (except roots) of the botanical species Chenopodium ambrosioides var anthelminticum Linn., belonging to the family Chenopodiaceae.
Isolation It is isolated by the repeated fractional distillation of the volatile oil of chenopodium (American wormseed oil) under vacuo and collecting the fraction boiling at 95-98°C.
Characteristic Features Ascaridiole is a viscid yellow oily liquid having a very peculiar and most disagreable odour and flavour. It is highly unstable and is prone to explode when either subjected to heat or when treated with organic acids, e.g., acetic acid; and with inorganic acids, e.g., sulphuric, nitric; hydrochloric and phosphoric acids. It being a peroxide liberates I2 from KI in acetic acid
solution. It is soluble in hexane, pentane, ethanol, toluene, benzene and castor oil. Its physical characteristics are: mp + 3.3°C; bp0.2 39-40°C; [α]20D 0.00; d204 1.0103;
Prepared Synthetically Ascaridiole may be synthesized from µ-terpinene by treatment with oxygen, chlorophyll and light as given below:
Identification As ascaridiole does not produce any crystalline derivative, therefore, it is usually characterized by the help of the following two specific reactions:
1. Formation of cis-1:4-Terpin [C10H18(OH)2]: Ascaridiole on reduction with H2 and Pd as a catalyst gives rise to the formation of cis-1, 4-terpin as follows:
The resulting cis-1, 4-terpin is optically inactive and also it is not identical with 1, 8-terpin, although the two compounds have similar melting points i.e., 116–117°C.
2. Formation of Ascaridole Glycol: Ascaridole upon oxidation with FeSO4 yield chiefly a ‘glycol’ which is not steam-volatile viz., ascaridole glycol. Consequently, this glycol may be further characterized by the formation of its monobenzoate (mp 136-137°C) and dibenzoate derivatives (mp 116.5°C).
Uses
1. It has been used as an anthelmintic (Nematodes).
2. It is also employed for eliminating hookworms and roundworms.
3. It is used most frequently in large number of medical and veterinary formulations.
Note Estimation of Ascaridole* Ascaridole may be determined quantitatively by the method described in the Extra Pharmacopoea, which is developed by Cocking and Hymas and based upon the oxidizing property of the ‘peroxide function’ exclusively present in it on the strongly acidified solution of KI (with HCl and glacial acetic acid). Thus, the liberated I2 is titrated with sodium thiosulphate (Na2S2O3) using freshly prepared starch solution as an indicator (colour change from blue to colourless) under the specified experimental parameters.
Precautions
1. Addition of oxygenated constituents must be avoided in the assay procedure that may give rise to eroneous results.
2. As the liberated iodine is capable of being absorbed by unsaturated components present in the volatile oil, it is absolutely necessary to carry out the assay at low temperature so as to maintain such secondary reactions at the lowest level.
