Лабданум

Labdanum is obtained from two Mediterranean shrubs: Cistus ladanifer, the gum rockrose of the western Mediterranean, and Cistus creticus, the pink rockrose of the eastern Mediterranean. The leaves of Cistus ladanifer yield a fragrant oleoresin known as labdanum. To protect itself from the sun and heat, the shrub produces a gum that envelops its twigs and leaves. Cistus ladanifer is an evergreen shrub 1 to 2.5 m tall and wide, native to the western Mediterranean region. Its flowers have five papery white petals, usually with a red to maroon spot at the base. In Spanish it is called jara pringosa, meaning sticky shrub. Labdanum is produced today mainly for the perfume industry. It was historically used in herbal medicine and is still used in the preparation of some perfumes and vermouths.

The raw gum is a black or sometimes dark brown, fragrant mass containing up to 20% or more of water. It is plastic but not pourable, and becomes brittle with age. The absolute is dark amber-green and very thick at room temperature.

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Harvest

Manual pruning of the branches begins in July, when they are full of resin, and only the shoots of the year are harvested. Once cut, the branches are gathered in bundles of 25 kg and taken to the processing plant. If it rains too much during the harvesting period, the plant's resin is washed away. If it does not rain and the air is too dry, the plant suffers water stress, loses some leaves and produces less resin. The plant needs about three years to grow enough before its branches can be cut. Wild cistus is picked by hand in summer and early autumn, on wheat fields that are left fallow for two to three years and that wild cistus repopulates naturally.

Chemistry

The resin is a complex mixture of terpenoid and phenolic compounds, represented mainly by labdane-type diterpenes and methylated flavonoids. Labdanolic acid is a major compound in labdanum resin. Labdanolic acid has the molecular formula C₂₀H₃₆O₃ and a molecular weight of 324.5. A methanolic labdanum absolute represented about 70% of the resin, and its diterpenoid and flavonoid fractions about 75% and 15% of the absolute. Flavonoids account for between 14 and 28% of the resin in plants harvested in summer, and between 6 and 16% in plants harvested in winter.

Labdanolic acid does not absorb UV radiation, so classical HPLC methods with UV detectors cannot detect it. Labdanum absolute has a spectrophotometric sun protection factor near 5, mainly because of its flavonoids, whose own factor is 13.