Lignane

RESEARCH OF LIGNANS AND ESSENTIAL OILS FROM THE ROOT ARCTIUM LAPPA L. 

Lignans show strong antitumor, antiviral and antibacterial activity, as well as influence upon expression of the tumor necrosis factor-alpha. 

Separation of chloroformic fraction of raw material by a polyamide sorbent with the following individual fractions elution and crystallization allowed to study lignans of burdock with IR-, mass- and NMR spectroscopy. In result, aixtiin, arctigenin, lappaols were identified. Sepai ation of essential oils was provided by the method two of State Phaiiuacopeias of the Ukraine. Essential oils were analyzed by the means of gas chromatography. 

Heterolignans, synthetic analogs of lignans containing heterocylic fragments 99H(51)1443. 

Bioactive polyphenol acids and lignans with 0-heterocyclic fragments and terpenoid 8-lactones as components of traditional Chinese drugs 98PAC547. 

The structure of carpanone (1) was revealed by Australian scientists in 1969.1 Carpanone, a hexacyclic molecule and host of five contiguous stereogenic centers, is a lignan found in the bark of the car-pano tree. 

Lawesson s reagent 475 f., 738, 742, 746, 752 Lederle 562 lepicidin aglycon 595 f. ligand-accelerated catalysis 681 f. lignane 95... 

The most useful of the insertion processes is the intramolecular reactions that occur with high selectivity for the formation of five-membered ring products. The electrophilic nature of the process is suggested by C-H bond reactivity in competitive experiments (3°>20 >1°) [76, 77]. Asymmetric catalysis with Rh2(MPPIM)4 has been used to prepare a wide variety of lignans that include (-)-enterolactone (3) [8], as well as (R)-(-)-baclofen (2) [7],2-deoxyxylolactone (31) [80,81],and (S)-(+)-imperanane (32) [82].Enantioselectivities are 91-96%... 

Podophyllotoxin, a plant lignan, is a potent antimitotic agent (Figure 6.61). An enantioselective synthesis of (—)-podophyllotoxin was achieved via the enzymatic desymmetrization of an advanced meso-diacetate, through PPL-mediated diester hydrolysis [157]. 

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