A new naphthoquinoid identified as 6-oxo-3, 4, 4a, 5-tetrahydroxy-2, 2-dimethylnaphtho-1, 2-pirane (6) has been isolated from an antibacterial, methanolic extract of leaves and branches of Lippia sidoides cham. Beside to the new quinone, five other know substances were isolated, and isocatalponol. The following fatty acids were also identified: palmitic, stearic, behenic, arachidic and lignoceric.