The chemical profile and antioxidant capacity of Juniperus virginiana, J. excelsa, and J. sabina essential oil (EO) fractions as a function of time was the subject of this study. The hypothesis was that, capturing EO in sequential timeframes during hydrodistillation would generate fractions containing unique compositions and antioxidant capacity. In J. virginiana, the highest limonene (43%) was found in the 0–5 min oil fraction, with safrole (37%) being highest in the 10–20 and 20–40 min fractions, and elemol (34%) being highest in the 160–240 min fraction. In J. excelsa, α-pinene (34-36%) was the highest in the 0–5 min fraction and in the control (non-stop 0–240 min distillation) oil, limonene (39%) was the highest in the 0–10 min fractions and cedrol (50-53%) was the highest in the 40–240 min fractions. In J. sabina, sabinene (80%) was highest in the 0–3 min fraction. The highest antioxidant capacity of J. virginiana was demonstrated by the 5–10 min fraction; the one in J. sabina by the 3–10 min fraction; and, the one in J. excelsa, by the control. The kinetics regression models that were developed can predict EO composition of the three juniper species eluted at different timeframes. Various industries could benefit from the results from this study.

Vellozia gigantea is a rare, ancient, and endemic neotropical plant present in the Brazilian Rupestrian grasslands. The dichloromethane extract of V. gigantea adventitious roots was phytotoxic against Lactuca sativa, Agrostis stolonifera, and Lemna paucicostata, and showed larvicidal activity against Aedes aegypti. Phytotoxicity bioassay-directed fractionation of the extract revealed one new isopimaradiene, 8(9),15-isopimaradien-1,3,7,11-tetraone, and three new cleistanthane diterpenoids, 7-oxo-8,11,13-cleistanthatrien-3-ol, 3,20-epoxy-7-oxo-8,11,13-cleistanthatrien-3-ol, and 20-nor-3,7-dioxo-1,8,11,13-cleistanthatetraen-10-ol. These new structures are proposed based on interpretation of ¹H, ¹³C, COSY, NOESY, HSQC, and HMBC NMR data. 8(9),15-isopimaradien-1,3,7,11-tetraone was especially phytotoxic with an IC₅₀ value (30 μM) comparable to those of commercial herbicides clomazone, EPTC, and naptalam. In addition, 7-oxo-8,11,13-cleistanthatrien-3-ol provided 100% mortality at a concentration of 125 ppm against one-day-old Ae. aegypti larvae. Our results show that ancient and unique plants, like the endangered narrowly endemic neotropical species V. gigantea present in the Rupestrian grasslands, should also be protected because they can be sources of new bioactive compounds.