Essential oils, chemical stimulation of resin and occurrence of galls in three Amazonian species of Protium

Protium is the most frequent genus of Burseraceae in the Adolpho Ducke Forest Reserve (Manaus, Amazonas), which is where its species were previously identified and mapped and this has favored various studies of this central Amazon forest. A number of P. divaricatum Engl., P. opacum Swart and P. strumosum Daly trees were selected with the objective of providing information about their chemical and biological aspects. Resin exudation was stimulated with the use of ethephon and the essential oils from the aerial parts and the resin were evaluated using GC. The occurrence of galls was also registered. The hydrocarbon sesquiterpene ß-caryophyllene was detected in high percentages in the essential oils of leaves and twigs of P. divaricatum (52.75% and 14.74%) and P. opacum (39.55% and 17.86%), respectively. The predominant oxygenated sesquiterpenes were spathulenol in the leaves (19.52%) and twigs (31.29%) of P. divaricatum, in addition to khusimone (32.36%) in the twigs of P. opacum. Monoterpenes were identified in the essential oils of the P. strumosum resin, with p-cymene (58.97%) predominating in the naturally exuded resin, limonene (61.45%) and p-cimen-8-ol (53.92%) in the resin of the first and second extraction with ethephon, respectively. On the trees, galls were identified that will help in the identification of the three species.