butanoic acid
Deherainia smaragdina (Theophrastaceae)
The name 'emerald flower' is not an official one, this plant doesn't have an English name. It is a rarity from tropical Mexico, a small tree with beautiful green flowers of 2-3 cm, included here because of their surprisingly unpleasant smell (sour cheese, Danish type!). The Botanic Garden in Copenhagen harbours a specimen and informs that the flowers smell of butanoic acid. However, other lower aliphatic carboxylic acids are evidently present.
1,8-cineole
and alpha-pinene
Eucalyptus
Eucalyptus globulus (Myrtaceae) Tasmanian blue gum, Fever tree
The large genus Eucalyptus includes some 600 species. Most of
them are native to Australia, where eucalyptus dominates as the forest
tree. Several species are planted and spread through sub-tropic regions
around the world, e.g. in the Mediterranean countries. Malaria was extinguished
from the swampy Paludi Pontine region near Rome through plantation with
Tasmanian blue gum. The word malaria is Italian (mala aria) for 'bad air'.
Originally it was believed that the disease was caused by the foul smell
from the swamps. The fragrant eucalyptus trees should freshen the air.
Today, the beneficial effect is explained by a reduction of the mosquitos
transferring the disease. The water-demanding eucalyptus trees partly
dried out the swamps, and the essential oil of the fallen leaves possibly
hampered the development of the mosquito's larvae.
Tasmanian blue gum is a fast-growing, large tree making a good shadow.
The peeling bark makes the white stem appear. The blue-green leaves are
dimorphic. On young shoots they are oval whereas on mature branches they
are characteristically sickle-shaped. The yellow-white flowers consist
of filaments only. The leaves contain the well known eucalyptus oil, used
in lozenges, tooth-paste, etc. Its main constituent is 1,8-cineole or
eucalyptol (ca. 65 %), having a fresh and slightly camphoraceous odour.
Moreover, the oil is rich in alpha-pinene (> 15 %) [6].
The essential oil from another eucalyptus, E. citriodora, is
utilized as a source of citronellal
(> 70 %).
4,5-dimethyl-3-hydroxy-2[5H]-furanone,
fenugreek lactone, sotolone
Trigonella foenum-graecum (Fabaceae)
Fenugreek, somewhat resembling sweetclover and lucerne (alfalfa), is a sub-tropical member of the pea family. It has been cultivated since Antiquity for its seeds, being one of the main ingredients of the mixed spice curry. Moreover, the seeds have interesting medicinal properties.
The characteristic irregular, brick-red seeds have no essential oil. Their flavour is due to trace amounts of the extremely powerful odorant 4,5-dimethyl-3-hydroxy-2[5H]-furanone, also called fenugreek lactone or sotolone [59]. Its odour detection threshold in water is as low as 0.001 ppb, meaning that 1 g of this compound dissolved in one million tonnes of water can be perceived! It has a celery and maple syrup-like odour. It belongs to the group of very powerful 'burnt sugar' odorants, characterized as being cyclic C6-alpha-enol-carbonyls.
Etymology: Gr. trigonon, triangle, because of the shape of the flowers; Lat. foenum-graecum, Greek hay, because this plant is used as an additive to hay in Greece. Horses and cattle love it.
(Z)-3-hexenyl benzoate, germacrene D,
beta-cyclocitral and 2-isobutyl-4-methylpyridine
Ficus carica (Moraceae) Common Fig
The figs (the genus Ficus) include more than 1000 species, all of them tree-like, with milky sap in stalks and leaves. Their inflorescense and pollination by tiny gall-wasps is one of nature's miracles.
Common fig is a native to southwest Asia and the eastern Mediterranean region. It grows to a large shrub or a small tree with smooth grey bark and deeply lobed leaves with three or five lobes. The fruits (the swollen receptacles with seeds) are mostly eaten dried as the fresh figs don't keep well.
Fig leaves have a characteristic sweet-green fragrance, perceptible when one stands close to the sun-warm trees or by handling the leaves. They have been extracted on a limited scale for perfumery use in Grasse in southern France. According to Arctander, fig leaf absolute is a dark green to brownish green, semi-solid mass or viscous liquid of a delicately sweet-green, herbaceous and somewhat woody odour with a mossy undertone.
Roman Kaiser, among 200 identified constituents of fig leaf absolute, found a number of olfactorily relevant N-containing trace constituents, one of them 2-isobutyl-4-methylpyridine, characterized by an attractive tobacco-like, green, herbaceous odor. Major odorants were linalool, benzyl acetate, methyl salicylate, beta-ionone and (Z)-3-hexenyl benzoate [137].
Buttery et al. identified germacrene D as a major volatile component in fig leaves. Other major volatiles were beta-cyclocitral, (Z)-3-hexenol and (Z)-3-hexenyl acetate [129].
Stemone ® (Givaudan), belonging to the palette of green-smelling odorants, has an odour somewhat reminiscent of that of fig leaves. It is used as a modifier for green notes in perfumery.
5-methyl-3-heptanone oxime
or Stemone ®
phenethyl alcohol
phenylacetaldehyde
Plumeria rubra (Apocyanaceae)
This little tree with thick branches and big leaves (until 45 cm long and 15 cm broad) is grown as an ornamental tree in the tropics and the sub-tropics. The fragrant flowers are red, but there are many varieties having yellow or white flowers. The tree has many names: Kembodja (Indonesia), Bermuda lily, and Frangipani (England, France), to name a few. Frangipani was the name of a Roman noble family.
The fragrance of the flowers is dominated by the two compounds phenethyl alcohol (or 2-phenylethanol) and phenylacetaldehyde [32].