Green leaf volatiles
Green leaf volatiles are organic compounds released by plants. They include C6-aldehydes such as (Z)-3-hexenal and derivatives such as (Z)-3-hexenol and (Z)-3-hexen-1-yl acetate. They are formed when plant tissues are damaged. In intact and healthy plant tissues, green leaf volatile levels are generally low.
In Arabidopsis, the major product in completely disrupted leaf tissue was (Z)-3-hexenal, while (Z)-3-hexenol and (Z)-3-hexenyl acetate were the main products in the intact parts of partially wounded leaves. Plants further convert (Z)-3-hexenol to (Z)-3-hexenyl acetate, which is even less active and more volatile.
Biosynthesis in plants
In plants, linolenic acid or linolenoyl residues of lipids are oxygenated by lipoxygenase to yield hydroperoxides. Hydroperoxide lyase cleaves the hydroperoxides to form C6-aldehydes and 12-carbon ω-oxo carboxylic acids. A portion of (Z)-3-hexenal is reduced by reductases to (Z)-3-hexen-1-ol, and further acetylation leads to the formation of (Z)-3-hexen-1-yl acetate.
Chemistry
Cis-3-hexen-1-ol has the formula C₆H₁₂O and a molecular weight of 100.16. Cis-3-hexenyl acetate has the formula C₈H₁₄O₂ and a molecular weight of 142.20.
Galbanum
Galbanum is an aromatic gum resin from certain umbelliferous Persian plant species in the genus Ferula, chiefly Ferula gummosa. Galbanum-yielding plants grow plentifully on the slopes of the mountain ranges of northern Iran.
Galbanum contains about 8% terpenes, about 65% of a resin which contains sulfur, about 20% gum, and a very small quantity of umbelliferone. It also contains α-pinene, β-pinene, limonene, cadinene, 3-carene, and ocimene. Galbanum absolute is a brown viscous liquid which will easily resinify over time, even with minimal exposure to air.
The fragrance wheel lists galbanum and green notes as examples of its Green subfamily.
History
Ancient Egyptians treasured galbanum as a sacred substance. Galbanum is mentioned in the Book of Exodus 30:34 as used in the making of the Ketoret. Hippocrates employed galbanum in medicine.
Galbanum's first use in fine modern perfumery is generally thought to have started the Green family of scents.
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Related: Acronychia Pedunculata · Adoxal · Agave · Algae · Aloe Vera · Aromatic Notes · Asparagus · Avocado
