Volatile oils in leaves of Bauhinia (Fabaceae Caesalpinioideae)

Leaves of seven species of Bauhinia (B. aculeata, B. alata, B. brevipes, B. forficata, B. longifolia, B. outimouta, B. pentandra, B. rufa and B. variegata) were submitted to volatile oil extraction by steam distillation. B. alata and B. outimouta, both of subgenus Phanera, failed to yield detectable volatile oils. Among the other species, all of subgenus Bauhinia, leaves of B. brevipes and B. rufa, both from savanna ecosystems, yielded 0.25 and 0.30% of volatile oil, respectively. Leaves of the other species, all from mesophytic forests, provided low amounts of oils. The oils obtained were analyzed by GC/MS. They consisted almost exclusively of sesquiterpenes. β-Caryophyllene, germacrene D and spathulenol were the compounds found more frequently and in relatively high proportions in some species. Oils from B. brevipes, B. rufa and B. variegata have similar composition, with germacrene D, spathulenol, δ- and γ-cadinene occurring in oils of all three species and some other similarities approaching B. brevipes from B. rufa. Quite distinctive compositions characterize the oils of B. aculeata, with high proportions of β-elemene and lepidozenol, and B. forficata, the only species in the present investigation yielding oils with a copaene isomer.