The genus Lippia is known for its aromatic character and medicinal use of its species as an alternative therapy. Essential oils of Lippia gracilis and L. origanoides collected in Pará and Maranhão were obtained by hydrodistillation and were rich in monoterpenes. The major compounds oil of L. gracilis were thymol (72.5%), p-cymene (9.3%) and thymol methyl ether (5.4%); for oil of L. origanoides were thymol (45.8%), p-cymene (14.3%), -terpinene (10.5%) and carvacrol (9.9%). The oils had potential larvicide against Artemia salina with LC50 values of 7.4 ± 0,2 μg.mL-1 to L. origanoides and 18.7 ± 0.2 μg.mL-1 to L. gracilis, both more active than lapachol (EC50 = 21.2 ± 2.2 μg/ ml). The essential oil of L. gracilis showed moderate scavenging capacity DPPH with EC50 value = 35.7 ± 3.32 μg.mL-1 about 8 times less active than the standard trolox (EC50 of 4.5 ± 0.1). Furthermore, the oil L. gracilis proved to be a good natural fungicide against the phytopathogen C. sphaerospermum with limit of detection of 5 μg, about 10 times less active than miconazole (DL = 0.5 μg). Moreover, the oil L. origanoides no showed significant activity (DL = 100μg).
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