Total Synthesis of the Antiallergic Naphtho-α-pyrone Tetraglucoside, Cassiaside C₂, Isolated from Cassia Seeds

Abstract

Toralactone 9-O-beta-d-glucopyranosyl-(1-->6)-beta-d-glucopyranosyl-(1-->3)-beta-d-glucopyranosyl-(1-->6)-beta-d-glucopyranoside (1, cassiaside C(2)), isolated from Cassia obtusifolia L. and showing strong antiallergic activity, was concisely synthesized employing glycosyl trifluoroacetimidates as glycosylation agents. The unique naphtho-alpha-pyrone structure of toralactone (5) was constructed by condensation of orsellinate 8 with pyrone 9 in the presence of LDA as developed by Staunton and co-workers. The naphthol of toralactone showed minimal reactivity as an acceptor and was screened with various glycosyl donors. It is finally concluded that sacrifice of an excess amount of the trifluoroacetimidate or trichloroacetimidate donors (6f/6g, 6.0 equiv) in the presence of a catalytic amount of TMSOTf (0.05 and 0.3 equiv, respectively) afforded excellent yields of the coupling product, which was otherwise only a minor product under a variety of conditions examined.

Anthraquinones from the Seeds of Cassia tora with Inhibitory Activity on Protein Glycation and Aldose Reductase

“…The seeds of C. tora are reputed in Oriental medicine as vision-improving, antiasthenic, asperient, and diuretic agents. 12) C. tora have shown to possess various biological and pharmacological activities including antihepatotoxic, 13) radical scavenging, 14) antiallergic, 15) antimutagenic, 16) antifungal, 17) and antimicrobial. 18) Previous phytochemical investigation on the seeds of C. tora have resulted in the isolation of several anthraquinone and naphthopyrone derivatives.…”

Inhibitory activities of major anthraquinones and other constituents from Cassia obtusifolia against β-secretase and cholinesterases

“…Cassiaside, a naphthopyrone glucoside and a major constituent of C. obtusifolia, has previously been reported to have a wide range of biological activities including antidiabetic (Lee et al, 2006;Jung et al, 2010a), antimutagenic (Choi et al, 1997), antioxidant (Choi et al, 1994), antimicrobial (Messana et al, 1991), hepatoprotective (Wong et al, 1989), antiallergic (Zhang and Yu, 2003), and antihypertensive activities .…”

Reversible Antifertility Effect of Cassia tora Linn in Male Rats

“…The fruits of the plant were collected in the moths of September and October of 2010 and study was carried out at Department of Zoology, University of Rajasthan Jaipur, India. Cassia tora possess various medicinal and pharmacological activities these includes antihepatotoxic [13] , antiallergic [14] , antimutagenic [15] ., antifungal [16] , radical scavenging and antimicrobial [16][17][18][19][20][21][22][23][24][25] .The chemical constituent of the plant Cassia tora are rubrofusarin triglucoside, non rubrofusarin gentobioside, demethyl-flavasperone, genitobioside, torachrysone gentibioside, torachrysone tetraglucoside, tora chrysone apioglucoside, torachrysone, toralactone aloemodin, rhein, emodin, naphthalene, anthraquinone, methicillin-resistant [23][24][25][26] .…”