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Aloes are used in traditional medicine for arthritis and to treat skin irritations.
These indications could point to the plants having anti-inflammatory activity.
Methanolic extracts of dried leaves of 53 Aloe species were tested in the cyclooxygenase-1
assay. Cyclooxygenase is one of the key enzymes in the biosynthesis of prostaglandins
that are implicated in inflammatory processes. The selected species are representative
of all chemotypes identified for the genus. The grass-like and scandent aloes
accumulate flavonoids in co-occurrence with the anthrone isomers aloin A and
B (A. boylei). This group is considered to be basal in Aloe and with the exception
of A. ciliaris, members of this chemotype showed high values of inhibition.
The flavanone producing species (A. pratensis, A. humilis and A.
pretoriensis)
also exhibited high values. These high values are similar to those recorded
for aloes which accumulate anthrones and chromones (A. wickensii). The two
main anthrone chemotypes in Aloe are represented by homonataloin- and aloin
accumulating species. No significant differences could be observed between
species accumulating aloin (A. ferox) when compared to the homonataloin-producing
species (A. mitriformis). It is interesting to note that species with similar
exudate profiles (A. mitriformis and A. comptonii) showed similar values of
inhibition.

South African Journal of Botany 2002, 68: 47–50