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EC number: 283-406-2
CAS number: 84625-32-1
Extractives and their physically modified derivatives such as tinctures, concretes, absolutes, essential oils, oleoresins, terpenes, terpene-free fractions, distillates, residues, etc., obtained from Eucalyptus globulus, Myrtaceae.
an in vivo metabolism study, 1,8-Cineole was administered by oral
route (via gastric intubation) to male albino rats at the dose of 800
mg/kg bw/day once daily for 20 days as a suspension in 1 % methyl
cellulose solution. Control rats were given only with vehicle (4 mL/kg
bw/day). Urine samples collected daily for 20 days, were adjusted to pH
3-4 and extracted with ether. The aqueous portion containing conjugated
metabolites was then subjected to acid hydrolysis and extracted with
ether (Chadha and Madyastha 1984). Both the ether extracts were
separated into neutral and acidic fractions. The total acidic fraction
was methylated using diazomethane (Chadha and Madyastha 1984).
Thin-layer chromatographic (TLC) analyses (silica gel G) of the
metabolites were carried out using hexane-ethyl acetate. Separation and
purification of the metabolites were accomplished by using a silica gel
column and hexane-ethyl acetate as the eluent.
acid methyl esters (250 mg) were subjected to TLC which showed the
presence of one major compound i.e., methyl ester of 1,8-dihydroxy
-10-carboxy p-methane and three minor compounds. The TLC analysis of the
neutral fraction (200 mg) showed the presence of one major i.e.,
2-hydroxy cineole and two minor metabolites. The neutral fraction (500
mg) obtained from hydrolysed urine on TLC analysis revealed the presence
of two major (similar to 2-hydroxy cineole and 3-hydroxy cineole) and
two minor metabolites. Based on the results, it is rather difficult to
predict the sequence of reactions taking place during the
biotransformation of cineole. However, one can envisage the formation of1,8-dihydroxy-10-carboxy-p-methane
through the intermediary of p-methane 1,8-diol and further metabolism is
possibly initiated by the oxygenation of the C-10 methyl group resulting
in the formation of p-methane-1,8,10-triol which undergoes stepwise
oxidation to the corresponding aldehydes and then to an acid. The
opening of the ether bridge in cineole could result in the formation of
a p-menthanoid cation with a positive charge either at C-1 or C-8 which
further gets readily neutralized by the attack of a hydroxide ion to
yield p- methane-1, 8-diol. The 2- and 3-hydroxy derivatives from
cineole have been reported in bacterial (MacRae et al. 1979) and fungal
systems (Nishimura et al. 1982) respectively. So it appears that the
microbial systems are more specific while carrying out the hydroxylation
of cineole unlike the mammalian system which hydroxylates at C-2 as well
as C-3 position. Both these hydroxylated derivatives are excreted as
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