**2. Material and methods**

quantities of substance easily renewable parts of the plant (leaf) thereby not affecting plant growth, development of chromatographic methods rapid and easy manipulation studies to

As part of a program conducted in our laboratory involving search for new sources of bioactive metabolites from Brazilian plants, we investigated the leaves of *Eugenia florida*. This species belongs to the family Myrtaceae. Compounds such as flavonoids, triterpenes, tannins and especially essential oils constituted of monoterpenes and sesquiterpenes have already been isolated from the genus Eugenia [Lunardi, et al., 2001]. The species of this family are widely distributed in the Brazilian forests, much of it is popularly known for its edible fruits, wood, essential oils or ornamental purposes [Consolini *et al*., 1999, Costa *et al*., 2005; Siani *et al*., 2000]. The most important genera of this family are: *Melaleuca*, *Eucalyptus*, *Psidium* and *Eugenia*

Since the fourth century B.C. there are reports of procedures for the collection of medicinal plants. The executioners Greeks, e.g., they collected their samples of poison hemlock (*Conium maculatum*) morning when levels are higher alkaloid coniina [Robinson, 1974]. Temporal and spatial variations in the total content, as well as the relative proportions of secondary metab‐ olites in plants occur at different levels and, despite the existence of a genetic control, the expression may undergo changes resulting from the interaction of biochemical processes, physiological, ecological and evolutionary [Gobbo, Lopes, 2007]. In fact, the secondary metabolites represent a chemical interface between plants and the surrounding environment. Therefore, their synthesis is often affected by environmental conditions [Gobbo, Lopes, 2007].

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identify the seasonal best months of collection.

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[Siani *et al*., 2000].

184 Column Chromatography

**Figure 1.** Betulinic acid

**1.1. Seasonal variation**
