Studies On The Chemical Constituents From The Bulbs Of Bolbostemma Paniculatum And Their Antitumor Activities

Bolbostemma paniculatum (Maxim.) Franquet, one of the plants of the genus Bolbostemma, family Cucurbitaceae, is a Triditional Chinese Medicine named as "Tu Bei Mu". Its rhizomes were traditionally used for the treatment of tumor as well as for detoxication. It has also been used to cure warts and used as an anti-inflammatory agent for mastitis and as an antidote for snake venoms. Tubeimosides Ⅰ ,Ⅱ, Ⅲ, isolated from the medicine, showed significant antitumor, anti-inflammatory and antitumor-promoting effects in preliminary communications. Recently studies have reported the isolation and structural elucidation of nine new triterpenoid saponins from Bolbostemma paniculatum, which have antiviral activity. In order to elucidate its active constituents and provide scientific foundation for its medicinal development, a systematic chemical study was conducted on the rhizomes of Bolbostemma paniculatum.In the course of our searching cytotoxic constituents from Bolbostemma paniculatum, twenty-six compounds were isolated by various chromatographic techniques and their structures were elucidated on the basis of spectroscopic methods.These compounds included: eight saponins: tubeimoside Ⅰ (BB-1) , tubeimoside Ⅳ (BB-2) , tubeimoside Ⅱ (BB-3) , tubeimoside Ⅲ (BB-4) , tubeimoside Ⅳ (BB-5) , 7β, 18, 20, 26-tetrahydroxy-20 (S) -dammar-24 E-en-3-O- α -L- (3'-acetyl) arabinopyranosyl- ( 1 → 2 ) - β -D-glucopyranoside (BB-6) , 7 β , 18, 20, 26-tetrahydroxy-20 (S) -dammar-24 E-en-3-O- α -L-(4'-acetyl) arabinopyranosyl- (1→2) -β -D-glucopyranoside (BB-7) ,7β, 18, 20, 26-tetrahydroxy-20 (S)-dammar-24 E-en-3-O- α -L-arabinopyranosyl-( 1→2)-β-D- (6'-acetyl) glucopyranoside ( BB-8) ; four heterocyclic compounds: maltol (BC-1), allantion (BC-2) , adenosine (BC-3) , cytosine (BC-4); one anthaquinone: emodin (BC-5) ; five triterpenoids and steroids: cucurbitacin B (BC-6) , stigmasta-7, 22, 25-triene-3-ol (BC-7), stigmasta-7, 22, 25-triene-3-O-β-D-gIucoside (BC-8) , β -sitosterol (BC-9) , daucosterol (BC-10) ; four sugars and their glycosides: β-D-glucose 2→13 -D-glucoside (BB-9) , maltose (BB-10) , α -hydroxyacetone-glucoside (BC-11) , sucrose (BC-12) ; two alkanes and one fatty acid: hentriacontane (BP-1) , triacontane (BP-2) , nonacosane (BP-3) , hexadecanoic acid (BP-4 ) . Among all of them, BB-2 was a new compound named as tubeimoside Ⅵ ; nine compounds, BP-1, BP-2, BP-3, BC-2, BC-4, BC-9, BC-10, BC-1 land BB-9 wereobtained from this genus for the first time. The profile of chemical constituents of Bolbostemma paniculatum was outlined.Crude extracts of Bolbostemma paniculatum and some isolated compounds were screened for the antitumor activities in vitro. The biological active extracts were determined. Total extract, chloroform fraction, and n-Butanol fraction have strong inhibition effects on HL-60, HeLa, MDA231, KB, WM451 cells. Petroleum fraction indicates the growth inhibitory activity against KB cell. Tubeimosides can inhibit the proliferation of SH-SY5Y cell. The cell cycle was analyzed by flow cytometry, the cell cycle of SH-SY5Y was arrested in S period by tubeimoside I . We used immunohistochemical approach to determine the expression of the hTERT and C-myc protein when SH-SY5Y was cultured with 10 μmol/L tubeimoside I , their expression and telomerase activity of SH-SY5Y were downregulated by tubeimoside I .To select a optimum purification process of the total saponins from Bolbostemma paniculatum by macroporous resin, static absorption test and deabsorption test were carried out. The single factor test, orthogonal experimental designs and variance analysis were applied to optimize the manipulation parameters of macroporous resin. The macroporous resin NKA possessed the strongest absorption ability to the total tubeimosides among the 9 resins studied, in addition to an easy de-absorption property. The optimum absorption conditions were concentration of feede 30 mg/ mL , diameter- height of the chromatography column 1: 7, the weight ratio of raw material and res...