The present invention relates to the use of a Eucalyptus extract in the preparation of a medicament or of a food supplement for the treatment and/or prevention of diseases or pathologies arising from a disorder of the reuptake of the following neuromediators: dopamine, serotonin and/or noradrenaline. Said extract is preferably enriched with at least one of the compounds of formula (I) or any one of the diastereoisomeric forms thereof: in which Rl, together with the carbon atom to which it is bonded, forms a C=CH2 group or a group , (Picture Remove) and R2 represents an isobutyl, a-isobutyl or (5- isobutyl group. The present invention relates also to the use of at least one of the compounds of formula (I) above in the preparation of a medicament or of a food supplement for the treatment and/or prevention of diseases or pathologies arising from a disorder of the reuptake of said neuromediators. There are many species of Eucalyptus (more than 600) , most of which are native to Australia and Tasmania, a small number to New Guinea and East Malaysia. The Eucalyptus belong to the myrtle family, and the origin of their name lies in the characteristic shape of their flowers. The word Eucalyptus in fact means "well covered", alluding to the operculum (formed of fused petals) which covers the stamen of the flowers. Eucalyptus are generally beautiful, large trees which can reach a height of 80 to 100 m in their country of origin (Australia) or 3 to 20 m in more temperate climates. Their bark, which is smooth, comes away in long strips of pale to greyish colour. They are generally characterised by foliar dimorphism. In the case of Eucalyptus globulus Labill, the juvenile leaves are oval-oblong, glaucous green, circled with blue, embracing and sessile, while the adult leaves are falciform, greyish-green and pendant, have a twisted petiole and are oriented vertically (equivalence of the two faces). The flower buds are formed of a calyx of quadrangular pyramid shape, covered by an operculum which lifts during flowering to reveal numerous stamen with long white filaments and yellow anthers. The fruits are capsules having a diameter of from 2 to 2.5 cm which contain black or brownish seeds. In phytotherapy, three species are principally used in the European pharmacopoeia: Eucalyptus globulus Labill, E. polybractea R.T. Baker and Eucalyptus smithii R.T. Baker. The leaves of the oldest branches (which leaves are falciform and petiolate), the essential oil and the eucalyptol obtained therefrom are used. Eucalyptus leaves are conventionally used by the oral and local routes to treat diseases of the respiratory system (bronchitis, inflammation of the throat, blocked nose, cold, etc.) or by application to treat wounds, skin ulcers, etc. The essential oil of Eucalyptus and eucalyptol (or 1,8-cineol) are used in numerous preparations for treating respiratory tract diseases owing to their antiseptic, mucolytic and expectorant activities. The essential oil is used as a repellent and in veterinary medicine. The pharmacological properties of the essential oil of Eucalyptus known to date are: antimicrobial, expectorant and anti-tussive properties (WICHTL M. and ANTON R., 1999 -Plantes therapeutiques - 177-179}, anti-inflammatory and anti-asthmatic properties (JUERGENS et al., 2003 - Antiinflammatory activity of 1,8-cineol (eucalyptol) in bronchial asthma : a double-bind placebo controlled trial -Respir. Med., 97 (3), 250-256), anti-diabetic properties (SWANSTON et al., 1990 - Traditional plant treatments for diabetes. Studies in normal and streptozotocin diabetic rats - Diabetologia, 33 (8), 462-464), anti-histaminic properties (IKAWATI Z. et al., 2001 - Screening of several Indonesian medicinal plants for their inhibitory effect on histamine release from RBL-2H3cells - J. Ethnopharmacol., 75 (2-3), 248-256), anti-cancer properties (TAKASAKI et al., 2000 - Cancer chemopreventive activity of euglobal-Gl from leaves of Eucalyptus grandis - Cancer Lett., 155 (1) : 61-65), anti-viral properties (TAKASAKI et al., 1990 -Structures of euglobal-Gl, -G2 and G3 from Eucalyptus grandis, three new inhibitors of Epstein virus activation -Chem. Pharm. Bull. 38 (5), 1444-1446) and anti-HIV properties (WICHTL M. and ANTON R., 1999 - Plantes therapeutiques - 177-179). Unexpectedly and surprisingly, the Applicants have revealed the use of a Eucalyptus extract in the preparation of a medicament or of a food supplement for the treatment and/or prevention of diseases or pathologies arising from a disorder of neuromediator reuptake. The field of the present invention is, therefore, a Eucalyptus extract for which valuable pharmacological properties have been observed and new therapeutic uses have accordingly been envisaged. The present invention does not relate to the essential oil of Eucalyptus as such, for which an abundant bibliography has been noted. The medicament or food supplement is advantageously intended for the treatment and/or prevention of pathologies arising from a disorder of neuromediator reuptake selected from the group: - neurological illnesses, diseases or disorders, - psychiatric illnesses, diseases or disorders, - memory, attention and vigilance disorders related to neurological and psychiatric illnesses, diseases or disorders, - functional somatic disorders, - dependence on addictive substances. The treatment and/or prevention of said diseases or pathologies preferably comprises inhibiting the reuptake of the neuromediators. Within the scope of the present invention, "neuromediators" are understood as being: dopamine and/or serotonin and/or noradrenaline. Within the scope of the present invention, "Eucalyptus" is understood as meaning the species belonging preferably to the subgenera Eudesmia, Symphomyrtus and Corymbia and more especially the following species: Eucalyptus globulus L. , Eucalyptus pulverulenta Sims, Eucalyptus kartzoffiana L. A. S. Johnson 1 Blaxell, Eucalyptus macrocarpa Hook., Eucalyptus clnerea F. Muell.ex Benth., Eucalyptus dorrigoensis (Blakely) L.A.S. Johnson 1 K. D. Hill, Eucalyptus leptopoda Benth., Eucalyptus occidentalis Endl., Eucalyptus viridis R. T. Baker, Eucalyptus polybractea R.T. Baker and Eucalyptus smlthii R.T. Baker. Those examples illustrate the present invention without, however, limiting the scope thereof. The Eucalyptus extract is advantageously obtained from Eucalyptus leaves, flowers, fruits, stems or trunk, preferably from Eucalyptus leaves. The Eucalyptus extract used according to the present invention is advantageously characterised in that it comprises at least one compound of formula (I) or any one of the diastereoisomeric forms thereof. Said formula (I) includes inter alia four compounds of the macrocarpal family, namely: - macrocarpal A: ( 5- ( (1R) -1- ( (US, 7R) -7-hydroxy-3, 3, 7 ,11-tetramethyltricyclo(6.3.0.0(2,4))undec-11-yl)-3-methylbutyl)-2,4,6-trihydroxybenzene-l,3-dicarbaldehyde) in which Rl, together with the carbon atom to which it is bonded, forms the group and R2 represents a p- isobutyl group. (Picture Remove) Empirical formula: C28H40O6 Molecular weight: 472 g/mol The fraction by weight of macrocarpal A in the Eucalyptus extract according to the present invention is advantageously greater than or equal to 0.1% and strictly less than 3%. - macrocarpal B : (5-((1S)-1-((11S,7R)-7-hydroxy-3, 3, 7,11-tetramethyltricyclo(6.3.0.0(2,4))undec-11-yl)-3-methyl-butyl)-2,4,6-trihydroxybenzene-l,3-dicarbaldehyde) in which Rl, together with the carbon atom to which it is bonded, forms the group and R2 represents an