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Thirty-six compounds (131-167) having a coleon-type structure were isolated from
eleven Plectranthus and ten Coleus species, where most of the compounds have been
isolated from P. edulis and C. coerulescens (Table 9a-c). The coleon-type compounds
differ from the royleanones in that ring C is aromatic in coleon-type compounds as
apposed to having a hydroxybenzoquinone or p-quinoid ring system.
Compounds 131-148 (Table 9a) differ in ring B with regard to positions 6 and 7 as they
both could be saturated as in 131, or oxidized, with either a hydroxy or carbonyl group
(132-135) or two carbonyl groups (136-145). Alternatively either C-6 or C-7 could be
oxidized as in 132-134. Compounds 138 to 141 are the only compounds where the
methyl group/s at C-15 have been oxidized to an alcohol or acetyl group, while 134 is the
only compound where the methyl group at C-20 has been oxidized to an alcohol.
Plectranthol B (131), has an aromatic substituent at C-19 with a prenyl group occurring at
C-12. In compounds 146 to 148, an oxygen bridge is formed between C-20 and either C-
6 or C-7. Compound 147 has a methoxy group present at C-20 while 148 has a carbonyl
function at C-7.
Table 9a: Coleon-type abietanes isolated from Plectranthus and Coleus species
Compound Name Synonym
131
132
133
134
135
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12-O-(3-methyl-2-butenoyl)-
19-O-(3,4dihydroxybenzoyl)-11hydroxy-8,11,13-abietatriene7α,11-dihydroxy-12-
methoxy-8,11,13-abietatriene
11,12-dihydroxy-8,11,13abietatriene-7-one
11,12,20-trihydroxy-8,11,13abietatriene-7-one
6β,11,12,14-tetrahydroxy-
8,11,13-abietatriene-7-one
Isolated from
Plectranthus
(P) or Coleus
(C) species
Plectranthol B P. nummularius
11,20dihydroxysugiol
11hydroxysugiol
5,6dihydrocoleon
U
Reference
Narukawa et al.
2001
P. elegans Dellar et al., 1996
P. cyaneus
P. cyaneus;
C. forskohlii
P. argentatus
Horvath et al.,
2004
Horvath et al.,
2004;
Lingling et al.,
2005
Alder et al.,
1984a
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