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Isolation of cyclocolorenone from the essential oil of Ledum palustre
Abstract
Summary From a carbon dioxide extract and also from the essential oil of the leaves ofLedum palustre L. the sesquiterpene ketone cyclocolorenone, hitherto unreported for this medicinal plant, has been isolated. The structure proposed for it previously has been confirmed by NMR and mass spectroscopy and also by the production of hydrogenation products.
... The major components present in the essential oil of L.palustre are (+) -ledol [4] , (−) -palustrol [4,5] , (−) -cyclocolorenone [4] , myrcene, p-cymene and limonene [4,6] . Ledol was isolated first time from L. palustre in 1948 [7] ; cyclocolorenone thirty years later [8] . Isolation of volatile compounds from the plants by the sub-critical fluid extraction technology allowed to obtain more components which could not be found by conventional methods (steam distillation, Soxhlet extraction) [9] . ...
... The major components present in the essential oil are (+)-ledol [43][44][45], (−)-palustrol [43,46,47], (−)-cyclocolorenone [43], myrcene, p-cymene and limonene ( Fig. 1) [1,42,43]. Ledol was isolated first time from Ledum palustre in 1948 [50,51]; cyclocolorenone thirty years later [52]. ...
Rhododendron tomentosum Harmaja (previously: Ledum palustre) is a fragrant evergreen shrub found in peaty soils in northern Europe, Asia and North America, commonly referred to as wild rosemary, marsh tea, marsh rosemary or northern Labrador tea. At least since the eighteenth century it has been used in ethnomedicine for the treatment of various ailments, such as rheumatism, cough, cold and insect bites, as well as a repellent. The essential oil of wild rosemary with the rich polyphenolic fraction possesses analgesic, anti-inflammatory, antimicrobial, antiviral, antifungal and insecticidal potential, demonstrated by in in vivo and in vitro studies. In addition, recent scientific researches reported the promising antidiabetic, antioxidant and anticancer properties. This review summarizes the information concerning taxonomy, botany, ecology, chemical composition, biological activities, toxicology and traditional and contemporary application of Rhododendron tomentosum plants.
... The predominance of cyclocolorenone, observed in the essential oils from D. brasiliensis, was not previously reported in other Drimys oils and could be used as chemoauxiliary in its taxonomy. This ketone has a restricted occurrence, being reported in Pseudowintera colorata (Corbett and Speden, 1958) and Tasmannia (Hisashi et al., 2002) among the family Winteraceae, Solidago canadensis (Jacyno and Montemurro, 1991), Ledum palustre (Mikhailova et al., 1978), Magnolia grandiflora (Schühly et al., 2001), and in liverworts such as Porella species (Asakawa et al., 1976), Frullania and Schusterella (Asakawa et al., 2003) and Bazzania trilobata (Nagashima et al., 1996), and can be easily obtained (by hydrodistillation or solvent extraction), and characterized by GC or GC/MS, due its particular Retention Index (Table 1) and mass spectra (Fig. 1). Therefore, its investigation in dichloromethane extracts by GC/MS using small amounts of plant material consists of a fast method to detect this marker compound. ...
The essential oils obtained from Southern Brazilian native Drimys brasiliensis Miers and Drimys angustifolia Miers were analyzed by GC and GC/MS. The oils from leaves of both species showed predominance of monoterpenoids, while the oils from stem barks were characterized by sesquiterpenoids. Bicyclogermacrene (20.0% in leaves and 25.4% in stem bark) and drimenol (1.4% in leaves and 26.2% in stem bark) were the most abundant in D. angustifolia, and cyclocolorenone (from 16.0% to 32.3% in fresh and dried leaves and almost 50% in stem bark) in D. brasiliensis. The oil from fruits of D. brasiliensis was also analyzed and presented 31.0% of cyclocolorenone. The predominance of this unusual aromadendrane-type sesquiterpene in D. brasiliensis essential oils could be used as a chemosystematic marker.
Background
The fractionation of the n-hexane phase of the EtOH extract from the leaves of Duguetia lanceolata (Annonaceae) led to the identification of the sesquiterpene (-)- cyclocolorenone.
Objective
Chemical characterization, including determination of the absolute stereochemistry, and in vitro evaluation of antileishmanial activity of the sesquiterpene (-)-cyclocolorenone, isolated from D. lanceolata were carried out.
Methods
(-)-Cyclocolorenone was isolated from D. lanceolata leaves using different chromatographic steps and its structure was defined by analysis of NMR and ESI-HRMS data. Additionally, the absolute configuration of (-)-cyclocolorenone was ambiguously assigned by means of vibrational circular dichroism (VCD). Antileishmanial activity of (-)-cyclocolorenone was evaluated on promastigote and amastigote forms of Leishmania (Leishmania) amazonensis. The integrity of the cell membrane of L. (L.) amazonensis was analyzed using the SYTOX green probe.
Results
(-)-(1R,6S,7R,10R)-Cyclocolorenone displayed activity against promastigotes and amastigotes forms of L. (L.) amazonensis with IC50 of 4.54 and 28.44 , respectively. Furthermore, this compound was non-toxic in J774 macrophage cells (CC50 > 458.71 ) with a selectivity index > 100 (promastigotes) and > 32.2 (amastigotes). Additionally, (-)-cyclocolorenone was observed to target the parasite cell membrane.
Conclusion
Obtained data suggested that (-)-cyclocolorenone, in which absolute configuration was determined, can be considered as a scaffold for the development of new drugs for the treatment of leishmaniasis.
The essential oils extracted from leaves of the Southern Brazilian native species Drimys angustifolia Miers (DA) and Drimys brasiliensis Miers (DB) by Clevenger distillation were analyzed by gas chromatography/ mass spectrometry (GC/MS). The oils of DA and DB consisted predominantly of monoterpenoids and sesquiterpenoids. The largest components of DA oil were bicyclogermacrene (19.6%), sabinene (9.7%) and myrcene (5.2%), while DB oil was characterized by cyclocolorenone (18.2%), followed by terpinen-4- ol (8.7%) and alpha-gurjunene (6.9%). Laboratory tests were carried out to determine the repellency of the essential oils to the drywood termite Cryptotermes brevis (Isoptera: Kalotermitidae). It was observed that the oil showed repellency at the concentrations 25, 12.5, and 6.25 μg/mL. The oils of both species exhibited a negative repellency index, which represents repellent activity, except for DA oil at the highest concentration, which was attractive. Five deaths (11% of the termite sample) were observed at 25 μg/mL DA, in the fourhour repellency test, while four deaths occurred at 12.5 μg/mL (approximately 9%). The essential oil of DB did not cause any termite deaths.
The bioactive sesquiterpene lactones parthenolide and costunolide, as well as the tricyclic sesquiterpene cyclocolorenone, were extracted from the leaves of Magnolia grandiflora by supercritical extraction with carbon dioxide and by near-critical extraction with propane. Parthenolide, costunolide, and cyclocolorenone in the extracts were identified by H-1 NMR and quantified by HPLC. Results indicate that supercritical carbon dioxide selectively removed parthenolide, costunolide, and cyclocolorenone when compared to standard liquid dichloromethane or near-critical propane extraction. HPLC traces show that the carbon dioxide extract is virtually clean of any chlorophyll or fatty material peaks which hinder isolation of these chemicals.
Cyclocolorenone, a sesquiterpene ketone of the aromadendrane class, was isolated from Magnolia grandiflora L. by bioassay-directed fractionation and its identity confirmed by UV, IR, NMR, and MS techniques. It showed good growth-inhibitory activity in an etiolated wheat coleoptile assay. Cyclocolorenone was also phytotoxic to greenhouse-grown corn, bean, and tobacco plants and displayed antimicrobial activity.