A new cytotoxic cholestane bisdesmoside from Ornithogalum saundersiae bulbs

Seven new 1-oxygenated cholestane glycosides from Ornithogalum saundersiae

As the continuous scientific research, seven new 1-oxygenated cholestane glycosides named osaundersiosides 1 A - 1 G were isolated from an EtOH extract of the bulbs of Ornithogalum saundersiae. Their structures were deduced by means of spectroscopic data, chemical evidence and the results of hydrolytic cleavage. The cytotoxicity and anti-inflammatory effects of osaundersiosides 1 A - 1 G were evaluated, but none of them displayed significant activities. [Formula: see text].

Structure and bioactivity of cholestane glycosides from the bulbs of Ornithogalum saundersiae Baker

Eight undescribed cholestane glycosides named osaundersioside A-H, along with three previously known compounds named osaundersioside I-K were isolated from Ornithogalum saundersiae Baker bulbs (Asparagaceae). Their structures were elucidated by extensive spectroscopic analysis and chemical methods. All isolates were evaluated for their cytotoxic activity and inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide (NO) production. Osaundersioside C was thus determined to exhibit specific cytotoxicity towards MCF-7 cell line with an IC₅₀ value of 0.20 μM, Osaundersioside H exhibited inhibitory effect on NO production in macrophages at the concentration of 10^-5 M, with inhibition rate of 56.81%.

Steroidal glycosides from Ornithogalum dubium Houtt

The phytochemical study of Ornithogalum dubium Houtt. (Asparagaceae) led to the isolation of five undescribed steroidal glycosides together with two known ones. Their structures were established by using NMR analysis and mass spectrometry as (25R)-3β-hydroxyspirost-5-en-1β-yl O-α-L-arabinopyranosyl-(1 → 2)-α-L-rhamnopyranoside, (25S)-3β-hydroxyspirost-5-en-1β-yl O-β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranoside, (22S)-16β-[(α-L-rhamnopyranosyl)oxy]-22-hydroxycholest-5-en-3β-yl O-β-D-glucopyranosyl-(1 → 4)-β-D-glucopyranoside, (22S,23S)-1β,3β,11α,16β,23-pentahydroxy-5α-cholest-24-en-22β-yl β-D-glucopyranoside, (22S,23S)-3β-[(β-D-glucopyranosyl)oxy]-22,23-dihydroxy-5α-cholest-24-en-16β-yl O-α-L-rhamnopyranosyl)-(1 → 4)-β-D-glucopyranoside. Their cytotoxic activities against two human cells, a lung carcinoma A-549 and a promyelocytic leukemia HL-60 cell lines, were evaluated by using the XTT method. The results showed no significant cytotoxicity on the tested cells. The influence of the potentiation of cisplatin cytotoxicity in A-549 cells was also investigated and a slight effect was observed only for the (25R) spirostane-type derivative.

Structural Characterization of Cholestane Rhamnosides from Ornithogalum saundersiae Bulbs and Their Cytotoxic Activity against Cultured Tumor Cells

Previous phytochemical studies of the bulbs of Ornithogalum saundersiae, an ornamental perennial plant native to South Africa, resulted in the isolation of 29 new cholestane glycosides, some of which were structurally unique and showed potent cytotoxic activity against cultured tumor cell lines. Therefore, we aimed to perform further phytochemical examinations of methanolic extracts obtained from Ornithogalum saundersiae bulbs, isolating 12 new cholestane rhamnosides (1-12) and seven known compounds (13-19). The structures of the new compounds (1-12) were identified via NMR-based structural characterization methods, and through a sequence of chemical transformations followed by spectroscopic and chromatographic analysis. The cytotoxic activity of the isolated compounds (1-19) and the derivatives (1a and 6a) against HL-60 human promyelocytic leukemia cells and A549 human lung adenocarcinoma cells was evaluated. Compounds 10-12, 16, and 17 showed cytotoxicity against both HL-60 and A549 cells. Compound 11 showed potent cytotoxicity with an IC₅₀ value of 0.16 µM against HL-60 cells and induced apoptotic cell death via a mitochondrion-independent pathway.

The chemistry and biological activity of the Hyacinthaceae

The Hyacinthaceae (sensu APGII), with approximately 900 species in about 70 genera, can be divided into three main subfamilies, the Hyacinthoideae, the Urgineoideae and the Ornithogaloideae, with a small fourth subfamily the Oziroëoideae, restricted to South America. The plants included in this family have long been used in traditional medicine for a wide range of medicinal applications. This, together with some significant toxicity to livestock has led to the chemical composition of many of the species being investigated. The compounds found are, for the most part, subfamily-restricted, with homoisoflavanones and spirocyclic nortriterpenoids characterising the Hyacinthoideae, bufadienolides characterising the Urgineoideae, and cardenolides and steroidal glycosides characterising the Ornithogaloideae. The phytochemical profiles of 38 genera of the Hyacinthaceae will be discussed as well as any biological activity associated with both crude extracts and compounds isolated. The Hyacinthaceae of southern Africa were last reviewed in 2000 (T. S. Pohl, N. R. Crouch and D. A. Mulholland, Curr. Org. Chem., 2000, 4, 1287-1324; ref. 1); the current contribution considers the family at a global level.

Three new homoisoflavanone glycosides from the bulbs of Ornithogalum caudatum

Phytochemical examination of Ornithogalum caudatum led to the isolation of three new homoisoflavanone glycosides. Their structures were elucidated, on the basis of the spectroscopic data and chemical evidence and by comparing them with those of known compounds, as (-)-7-O-methyleucomol 5-O-beta-D-glucopyranoside (1), (-)-7-O-methyleucomol 5-O-beta-rutinoside (2), and (-)-7-O-methyleucomol 5-O-beta-neohesperidoside (3), respectively.

Cholestane rhamnosides from the bulbs of Ornithogalum saundersiae

Phytochemical examination of the bulbs of Ornithogalum saundersiae yielded six cholestane rhamnosides, two of which had previously been isolated from the same plant material. However, detailed spectroscopic analysis of the aglycone led us to revise the configuration of the C-11 hydroxyl group of the latter two and reassign their structures as (22S)-cholest-5-ene-3 beta,11 alpha,16 beta,22-tetrol 16-O-alpha-L-rhamnopyranoside and (22S)-cholesta-5,24-diene-3 beta,11 alpha,16 beta,22-tetrol 16-O-alpha-L-rhamnopyranoside, respectively. The other four are new naturally occurring constituents and their structures were determined to be (22S)-cholest-5-ene-3 beta,11 alpha,16 beta,22-tetrol 16-O-(2,3-di-O-acetyl-alpha-L-rhamnopyranoside), (22S)-cholest-5-ene-3 beta,11 alpha,16 beta,22-tetrol 16-O-{2-O-acetyl-3-O-(3,4,5-trimethoxybenzoyl)-alpha-L-rhamnopyran oside}, (22S)-cholest-5-ene-3 beta,11 alpha,16 beta,22-tetrol 16-O-{2-O-acetyl-3-O-(p-methoxybenzoyl)-alpha-L-rhamnopyranoside} and (22S)-cholesta-5,24-diene-3 beta,11 alpha,16 beta,22-tetrol 16-O-(2,3-di-O-acetyl-alpha-L-rhamnopyranoside), respectively. The isolated compounds were evaluated for their cytostatic activity against leukemia HL-60 cells.

Saundersiosides C-H, rearranged cholestane glycosides from the bulbs of Ornithogalum saundersiae and their cytostatic activity on HL-60 cells

Six novel rearranged cholestane glycosides with a six-membered hemiacetal ring system, designated as saundersiosides C-H, were isolated from the bulbs of Ornithogalum saundersiae. Their structures were determined on the basis of spectroscopic analysis and the result of hydrolysis. The conformation of the six-membered hemiacetal ring of the rearranged cholestanes was shown to be almost a boat-form by molecular mechanics and molecular dynamics calculation studies. Among the isolated compounds, saundersioside E, F, G and H with an aromatic acid ester group at the glycoside moiety were found to be highly cytostatic to human leukemia HL-60 cells, showing IC50 values of 0.021, 0.019, 0.063 and 0.052 microM, respectively, which are as potent as those of the clinically applied anticancer agents, etoposide and methotrexate.