Of sesquiterpenes

Patchouli alcohol. Patchouli oil comes from Pogostemonpatchouli and the main constituent is patchouli alcohol [5986-55-0] (105) or patchoulol. Another component of the essential oil is norpatchoulenol (106), a norsesquiterpene derivative as a minor (3—5%) constituent, important ia determining the overall odor of the essential oil (197). The price of patchouli oil ia 1995 was 20.90/kg from Indonesia (69). Alarge proportion of the oil (40—60%) is comprised of sesquiterpene hydrocarbons that do not have much odor value. World production of the oil was at about 750 t ia 1984. It is valuable ia perfumery bases because of its characteristic woody, herbaceous odor (198). 

Tandem cyclization-cycloaddition of diazoketones in the synthesis of sesquiterpenes, possessing 7-oxabicyclo [2.2.1]heptane fragment 97F303. 

The oil prolialily oonsiscs of sesquiterpenes oi Leviv.yphu , Tayicri yields it chick green fnllowing characters t--... 

The oil contains about 60 per eeiit. of sesquiterpenes and 10 per cent, of seaqoiterpene alcohols. The principal sesqnileipcne ia probably cadinene, as indicated hy the following figures in comparison with those for eodinene obtained fvom oil of cade —... 

This sesquiterpene, or mixture of sesquiterpenes, is found to a considerable extent in nature, especially in clove oil, pimento oil, pepper oil, cinnamon oil, betel oil, copaiba oil, and numerous other essential oils. As isolated from these oils the sesquiterpene has the following characters —... 

Semmler and Mayer agree that the reagent used and the conditions of temperature, etc., govern the character of the sesquiterpene, or mixture of sesquiterpenes which result. By using sodium methylate very cautiously, they obtained a caryophyllene having the following characters —... 

The above considerations indicate the complex nature of the hydrocarbons known as caryophyllene. For practical purposes, however, the compounds indicated are obtained of practically definite melting-points, and, in spite of the complicated isomerism existing amongst most of them, are useful for identification of the sesquiterpene or mixture of sesquiterpenes, occurring naturally and known as caryophyllene . 

Table 2.2 Occurrence of sesquiterpenes and aromatic esters in the liverwort, Isotachis lyallii, in New Zealand (from Asakawa et al., 1997)...

Martin et al. (1974) collected specimens from 22 locations throughout the range of H. courbaril and identified a number of sesquiterpenes including caryophyllene [173], humulene [174], selinene isomers [175 is P-selinene], and other related compounds (see Eig. 2.48 for compounds 173-175). Caryophyllene and two selinene... 

Table 2.19 Distribution of sesquiterpene lactones in Ambrosia ambrosioides (from Seaman and Mabry, 1979b)...

Table 6.1 Distribution of sesquiterpene derivatives in populations of Cyperus rotundas (from Komai and Tang, 1989)...

Composites -have been reported (8) to contain a wide variety of sesquiterpene lactones and lactones of this type have been previously found in both Russian knapweed and yellow starthistle (9,10,11,12). The wide range of biological activity associated with sesquiterpene lactones, e.g., cytotoxicity, phytotoxicity, antineoplasticity, etc. (8) suggested the possibility that these compounds may play a role in the allelopathy of both Russian knapweed and yellow starthistle. 

Also, the presence of sesquiterpenes containing a-methylene-y-buty-rolactone groups suggested their implication in ENE disease since it has been shown that sesquiterpenes containing this particular functional group are often cytotoxic to mammalian cells (13). 

Isolation of Sesquiterpene Lactones. The ether extract was evaporated and dissolved in 952 ethanol. Then an equal volume of 42 aqueous lead acetate was added. After 1 hour the mixture was filtered to remove precipitated chlorophyll and phenolic products and the ethanol removed under vacuum. The aqueous layer was extracted with chloroform giving a dark colored oil from which the sesquiterpenes were isolated by a combination of chromatographic procedures, i.e., LH-20 gel permeation, silica gel using both packed columns and thin layer plates. A variety of solvents were also used to purify the individual sesquiterpene lactones, e.g., benzene-acetone (1 1), ethyl acetate, chloroform-methanol (9 1). On thin layer chromatographic plates, spots were visualized by spraying with 22 aqueous KMn04 solution. 

In a search for allelopathic agents from common weeds, Amaranthus palmerl S. Wats (Palmer amaranth) and Ambrosia artemisiifolia L. (Louisiana annual ragweed) have been analysed for their organic natural products. From A. palmerl phytol, chondrlllasterol, vanillin, 3-methoxy-4-hydroxynitrobenzene and 2,6-dimethoxy- benzoquinone were isolated. From the roots of Ambrosia artemisiifolia four polyacetylenes, a mixture of sesquiterpene hydrocarbons, methyl caffeate, and a mixture of 8-sitosterol and stlgmasterol were obtained. 

Table II. EFFECTS OF SESQUITERPENE LACTONES (15-24), 17-ACETOXYACANTHOAUSTRALIDE (25) and ARTEMETIN (26) ON SEED GERMINATION1 2...

Effects of Sesquiterpene Lactones on Seed Germination. Sesquiterpene lactones are common constituents of the Asteraceae but are also found in other angiosperm families and in certain liverworts (31,32). These highly bitter substances exhibit a wide spectrum of biological activities (J 3) which include cytotoxicity, anti-tumor, anti-microbial, insecticidal (34) and molluscicidal (35) properties. Furthermore, they are known causes for livestock poisoning and contact dermatitis in humans (33). Structure-activity relationship studies on sesquiterpene lactones have demonstrated that biological activity frequently depend on the presence of the cr... 

In contrast, nothing is known about B megapotamica and its relationship with other plants in its habitat. However, both P. hysterophorus and B megapotamica pose a serious hazard to animals who ingest these plants. P. hysterophorus has been implicated in allergic contact dermatitis common in many parts of India (11,12), and, as we shall see, B megapotamica contains a series of sesquiterpenes which are probably the most potent skin irritants known. 

Table IX. Effects of Sesquiterpenes (MW 204) Isolated from Ragweed on Seed Germination... 

Hwang DR et al (2006) Synthesis and anti-viral activity of a series of sesquiterpene lactones and analogues in the subgenomic HCV replicon system. Bioorg Med Chem 14(1) 83—91... 

The family Asteraceae is a prolific source of sesquiterpene lactones, among which, melampolides have been shown to inhibit the enzymatic activity of elastases. Melampolides are a common member of the Melampodi-inae subtribe. Examples of medicinal Asteraceae known to elaborate melampolides are Sigesbeckia orientalis L. and Mikania cordata (Burm.f.) B.L. Robinson. 

Mikania cordata is known to elaborate a series of sesquiterpene lactones, among which deoxymikanolide significantly inhibits acetic acid-induced writhing in mice (44,45). The plant also contains a series of melampolides that inhibit the enzymatic activity of elastase (46). 

Sumner H, Umit S, Knight DW, Hoult JRS. Chrysanthemum parthenium (L.) Bernh. Inhibition of 5-lipoxygenase and cyclooxygenase in leukocytes by feverfew Involvement of sesquiterpene lactones and other components. Biochem Pharmacol 1992 43 2313-2320. 

Herz W, Subramaniam PS, Santhanam PS, Aota K, Hall AL. Structure elucidation of sesquiterpene dilactones from Mikania scandens (L.) Willd. J Org Chem 1970 35 1453-1464. 

Matsuda H, Tadashi K, Iwao T, Hiroki U, Toshio M, Masayuki Y. Inhibitory effects of sesquiterpenes from bay leaf on nitric oxide production in lipopolysaccharide-activated... 

This sequence was successfully employed by Thomas [78] for the synthesis of sesquiterpenes such as 3-sinesal (4-232), and by Raucher and coworkers [79] for the synthesis of the germanocrolid (+)-dihydrocostunolide (4-233) (Scheme 4.50). 

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