Antitumor lignans

The approach also allows the synthesis of furans by employing ethoxymethylene malonate, followed by an eliminative decarboxylation. This method was used by Balme for a formal synthesis of the antitumor lignan burseran (6/1-294), starting from 6/1-290,6/1-291 and 6/1-292 via the furan 6/1-293 (Scheme 6/1.78) [139], Furans as 6/1-298 can also be obtained by Pd-catalyzed reaction of 2-propynyl-l,3-dicarbonyls 6/1-295 with aryl halides 6/1-296 in DMF, using potassium carbonate as base, as shown by Arcadi, Cacchi and coworkers (Scheme 6/1.79) [140]. 

In recent decades, a number of antitumor lignans have been synthesized, and their structure-activity correlations have been reported. Ring-A-opened podophyllotoxin lignans were synthesized by Michael Initiated Ring Closure (MIRC). Compound 67 showed the strongest inhibition of DNA topoisomerase II like 65 [55]. Naturally... 

A series of synthetic analogues of naturally occurring antitumor lignans, the ste-ganacins, were tested for inhibition of microtubule assembly in vitro. Spatial variation exists for both the biaryl junction [normal series stegane (70) and picrostegane... 

S J Torrance, JJ Hoffmann, JR Cole. Wikstromol, antitumor lignan from Wikstroemia foe-tida var. oahuensis Gray and Wikstroemia uva-ursi Gray (Thymelaceae). J Pharmaceu Sci 68 664-665, 1979. 

Torrance S J, Hoffmann J J, Cole J R 1979 Wikstromol. Antitumor lignan from Wikstroemia foetida var oahuensis Gray and Wikstroemia uva-ursi Gray (Thymelaeaceae). J Pharm Sci 68 664-665... 

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

N.A. Phenol, lignan, oleic acid, linoleic acid, protein, vitamins , E, folic acid.165166 An antioxidant, antitumor, antimitotic, antiviral, prevent breast cancer. Internally for premature hair loss and graying, strengthen bones and teeth. 

Kangas, L., Saarinen, N., and Mutanen, M. 2002. Antioxidant and antitumor effects of hydroxyma-tairesinol (HM-3000, HMR), a lignan isolated from the knots of spruce. Eur. J. Cancer Prev. 11, S48-S57. 

Lignans are a well-known class of widespread natural phenolic compounds that exhibit great structural and biological diversity and are commonly found in vascular plants from various families [1]. They are present at different levels of abundance in all plant parts, including roots, rhizomes, hardwood, bark, stems, leaves, flowers, fruits and seeds [2]. Lignans are of considerable pharmacological and clinical interest and are used in the treatment of cancer and other diseases [3]. The extensive pharmaceutical use of lignans is due to their antitumor, antiviral and hepatoprotective properties as well as many other beneficial activities. 

Taxus species are well known due to the antitumor and anticancer activities of their taxane diterpenoids, which have attracted many researchers to them [5,7,8]. In Taxus species (Taxaceae), lignans have been shown to occur in different parts of the tree, extending from the needles to the roots [5,8]. 

The best example of a lignan used as a lead compound is podophyllotoxin, an antimitotic compound that binds to tubulin, although podophyllotoxin has not been isolated from Taxus species,. Etoposide and teniposide are well-known compounds derived from podophyllotoxin, and their antitumor activity is due to the inhibition of topoisomerase II. 

Besides antitumor/anticancer activity, lignans are among the most potent antiviral compounds, although most of the lignans evaluated for antiviral potency belong to families of plants other than Taxaceae [3]. 

Lignans represent another class of compounds that have attracted a lot of attention due to their potent antitumor activities [121]. Molecules such as steganone (167), steganol (168)... 

Antitumor Activity of Naturally Occurring Lignans (Continued)... 

H Saito, H Yoshikawa, Y Nishimura, S Kondo, T Takeuchi, H Umezawa. Studies on lignan lactone antitumor agents.I. Synthesis of aminoglycosidic lignan variants related to podophyUotoxin. Chem Pharm Bull 34 3733-3740, 1986. 

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