Extracellular Localization of the Diterpene Sclareol in Clary Sage (Salvia sclarea L., Lamiaceae)

Abstract

Sclareol is a high-value natural product obtained by solid/liquid extraction of clary sage (Salvia sclarea L.) inflorescences. Because processes of excretion and accumulation of this labdane diterpene are unknown, the aim of this work was to gain knowledge on its sites of accumulation in planta. Samples were collected in natura or during different steps of the industrial process of extraction (steam distillation and solid/liquid extraction). Samples were then analysed with a combination of complementary analytical techniques (gas chromatography coupled to a mass spectrometer, polarized light microscopy, environmental scanning electron microscopy, two-photon fluorescence microscopy, second harmonic generation microscopy). According to the literature, it is hypothesized that sclareol is localized in oil pockets of secretory trichomes. This study demonstrates that this is not the case and that sclareol accumulates in a crystalline epicuticular form, mostly on calyces.

Recent progress in secondary metabolism of plant glandular trichomes

“…Most of the commercially-produced sclareol is derived from cultivated clary sage (Salvia sclarea), and subsequent extraction from the plant material. In clary sage, sclareol mainly accumulates in essential oil-producing trichomes that densely cover flower calices (Caissard et al 2012). Caniard et al recently cloned and functionally characterized two new diterpene synthase (diTPS) enzymes for the complete biosynthesis of sclareol using a transcriptome database obtained by deep 454-sequencing of cDNA from clary sage calices.…”

Enzymes for Synthetic Biology of Ambroxide-Related Diterpenoid Fragrance Compounds

“…2). Sclareol is isolated from inflorescences either by steam distillation or more efficiently by organic solvent extraction of dried plant material [21,36]. Several approaches for the conversion of sclareol into (-)-ambrox have been demonstrated [15,29,37].…”

“…In nature, sclareol is found in only a few plant species, including Cistus creticus (Cistaceae), Cleome spinosa (Brassicaceae), Nicotiana glutinosa (Solanaceae), and clary sage (Lamiaceae) [21,23]. In particular, clary sage accumulates large enough quantities of sclareol that it forms epi-cuticular crystals primarily on the surfaces of flower calyces and bracts [36]. Although sclareol was shown to have antimicrobial properties, its biological function in planta is unknown [67].…”

Avaliação do efeito vascular do diterpeno esclareol em ratos normotensos e hipertensos

“…O esclareol pode ser extraído a partir de inflorescências de Salvia sclarea L., uma erva da família Lamiaceae, que é mais comumente cultivada por seu óleo essencial. O relativamente fácil cultivo desta erva e seu alto rendimento tem incentivado produtores de sálvia a iniciar programas de melhoramento genético e expandir suas plantações [27] . Medicine [12] .…”

“…O diterpeno esclareol é extraído a partir de inflorescências de Salvia sclarea L., uma erva de relativamente fácil cultivo e alto rendimento [13,27] . Os estudos que utilizaram este composto evidenciaram suas ações anti microbianas, efeitos citotóxicos e citostáticos em linhagens de células leucêmicas e ações antitumorais [14][15][16][17] .…”