Cycloartane and Oleanane Saponins from EgyptianAstragalusspp. as Modulators of Lymphocyte Proliferation

Abstract

From the roots of Astragalus kahiricus DC., three known saponins, namely, astraversianin VI, astraversianin X, astragaloside VIII, and a new saponin were isolated and identified by spectral data. The structure of the latter was elucidated by spectral means and assigned as cycloastragenol 3- O-[ beta- D-(2',3'-diacetyl, 4'- trans-2-butenoyl)-xylopyranosyl], 6- O- beta- D-xylopyranoside (kahiricoside I). From the aerial parts of A. hamosus L., the known compounds azukisaponin V and peregrinoside I were isolated. As judged by in vitro tests, the saponins isolated from Astragalus spp. endemic to Egypt were not cytotoxic against a variety of human cancer cells. However, dose-related modulation of lymphocyte proliferation was observed, and structure-activity relationships are described.

Cytotoxic Activity of Crude Extracts fromAstragalus Chrysochlorus(Leguminosae)

“…In contrast, the saponins isolated from Astragalus spp. endemic to Egypt were not cytotoxic against a variety of human cancer cells (20).…”

Further Saponins and Flavonoids fromAstragalus verrucosusMoris

“…Thus astraverrucin VII (1) resulted as the 6¢-O-acetyl isomer of astraverrucin I. Cycloaraloside D (2) (also named peregrinoside II) and Cycloaraloside C (named also astrailienin A) (3) were also isolated for the first time from this source, although they were previously isolated from other Astragalus spp. : A. amarus (Isaev, 1991) and A. peregrinus (Verotta et al, 2001;2002) for (2), and A. amarus (Isaev & Abubakirov, 1990) and A. iliensis (Yu-Cun et al, 1990) for (3). These saponins showed the typical spectra of cycloastragenol diglycoside (two anomeric protons at d 5.0 and 6.59 for (2) and 4,26 and 5.35 for (3) in the 1 H spectrum, also supported by the presence of two anomeric carbons in the 13 C NMR spectra).…”

Astragaloside IV and cycloastragenol are equally effective in inhibition of endoplasmic reticulum stress-associated TXNIP/NLRP3 inflammasome activation in the endothelium

“…In China, A. membranaceus has been considered to be a healthenhancing herbal used for the treatment of metabolic and cardiovascular disorders, including diabetes and atherosclerosis. Although cycloastragenol is also present in the flowers and roots of A. membranaceus (Verotta et al, 2002), it can be generated from parent astragaloside IV through hydrolysis by intestinal bacteria (Zhou et al, 2012) (Fig. 1).…”