Supplementary Figure Legends from Milk Thistle and Prostate Cancer: Differential Effects of Pure Flavonolignans from Silybum marianum on Antiproliferative End Points in Human Prostate Carcinoma Cells

MEMS-based resonant mass sensors can be sensitive tools to measure the physical properties of cells such as their mass. We recently developed an array of sensors that have a uniform mass sensitivity for measuring the stiffness and the long-term growth rate of adherent human colon adenocarcinoma cells (HT-29). We demonstrated that for these adherent single cells, the cell growth rate increases with call mass, i.e. larger cells grow faster. The finding points to the fact that additional cell-size control mechanisms might be required for cell size homeostasis over generations and that growth rate is determined by the amount of the ribosomal machinery, which doubles during the cell cycle. Here, we expand our studies by presenting an additional sensor design with further optimization for higher uniformity of the mass sensitivity based on a detailed numerical analysis. We also demonstrate that MEMS resonant mass sensors can be used to measure physical changes in apoptotic cells. HT29 were treated with staurosporine, a potent drug that induces cellular apoptosis. Through Laser Doppler Vibrometery (LDV), we measured changes in the cells' apparent mass, and correlated these changes with optical images using dark field microscopy. Such real-time mass measurements of individual cells coupled with optical imaging can be a powerful tool to understand the physiological processes of cell growth and apoptosis.

Bioactivity-directed fractionation of an extract of the leaves of Alvaradoa haitiensis, using the KB (human oral epidermoid carcinoma) cell line, led to the isolation and identification of 10 new anthracenone C-glycosides, alvaradoins E-N (1-10), along with the known compound chrysophanol (11). The cytotoxicity of all compounds was evaluated, and preliminary structure-activity relationships are suggested. The most potent compounds in the in vitro assays (1 and 2) were evaluated in vivo versus the P388 (murine lymphocytic leukemia) model, and alvaradoin E (1) showed antileukemic activity (125% T/C) at a dose of 0.2 mg kg(-1) per injection when administered intraperitoneally.

AbstractExtracts from the seeds of milk thistle, Silybum marianum, are known commonly as silibinin and silymarin and possess anticancer actions on human prostate carcinoma in vitro and in vivo. Seven distinct flavonolignan compounds and a flavonoid have been isolated from commercial silymarin extracts. Most notably, two pairs of diastereomers, silybin A and silybin B and isosilybin A and isosilybin B, are among these compounds. In contrast, silibinin is composed only of a 1:1 mixture of silybin A and silybin B. With these isomers now isolated in quantities sufficient for biological studies, each pure compound was assessed for antiproliferative activities against LNCaP, DU145, and PC3 human prostate carcinoma cell lines. Isosilybin B was the most consistently potent suppressor of cell growth relative to either the other pure constituents or the commercial extracts. Isosilybin A and isosilybin B were also the most effective suppressors of prostate-specific antigen secretion by androgen-dependent LNCaP cells. Silymarin and silibinin were shown for the first time to suppress the activity of the DNA topoisomerase IIα gene promoter in DU145 cells and, among the pure compounds, isosilybin B was again the most effective. These findings are significant in that isosilybin B composes no more than 5% of silymarin and is absent from silibinin. Whereas several other more abundant flavonolignans do ultimately influence the same end points at higher exposure concentrations, these findings are suggestive that extracts enriched for isosilybin B, or isosilybin B alone, might possess improved potency in prostate cancer prevention and treatment.

Objectives: To determine the relative quantities of two hepatotoxic pyrrolizidine alkaloids, symphytine and echimidine, in teas prepared from comfrey leaves ( Symphytum officinale ), and to determine the potential contribution of the N -oxide forms of these alkaloids to levels of the parent alkaloids. Design: Comfrey leaves were purchased from three commercial sources and used to prepare tea in a manner consistent with the methods used by consumers. An extraction scheme was devised for extraction of the alkaloids, and a gas chromatographic method was developed to quantify the two major alkaloids, symphytine and echimidine. Recognising that the N -oxide derivatives of these alkaloids have also been identified in comfrey preparations, chemical reduction was applied to determine the total quantities of the alkaloids as free bases and as N -oxide derivatives. Results: The concentration of symphytine and echimidine varied considerably between teas prepared from leaves purchased from the different vendors of plant material. Moreover, a much higher concentration of symphytine was found in the tea when steps were included to reduce N -oxides prior to analysis. The treatment of pure symphytine with hot water did not generate the N -oxide derivative de novo . Conclusions: Since the pyrrolizidine alkaloids are known to be hepatotoxic, consumption of herbal teas made from comfrey leaves may be ill-advised. The concentration of pyrrolizidine alkaloids in such teas may be underestimated substantially unless the concentration of N -oxides is taken into consideration.

Complete separation, isolation, and structural characterization of four diastereoisomeric flavonolignans, silybins A (1) and B (2), and isosilybins A (3) and B (4) from the seeds of milk thistle (Silybum marianum) were achieved for the first time using a preparative reversed-phase HPLC method. In addition, three other flavonolignans, silychristin (5) isosilychristin (6) and silydianin (7), and a flavonoid, taxifolin (8) were isolated. Structures, including absolute stereochemistries of 1-4, were confirmed using 2D NMR and CD spectroscopy.

Three new (1-3) triterpenoids and one known (4) triterpenoid were isolated from an acid hydrolyzed methanol-soluble extract of the leaves of Abrus precatorius. Their structures were identified as (20S,22S)-3beta,22-dihydroxycucurbita-5(10),24-diene-26,29-dioic acid delta-lactone (1), 3-O-[6'-methyl-beta-D-glucuronopyranosyl]-3beta,22beta-dihydroxyolean-12-en-29-oic acid methyl ester (2), 3-O-beta-D-glucuronopyranosylsophoradiol methyl ester (3), and sophoradiol (4) by spectroscopic techniques including 2D NMR.

Six new xanthones, cratoxyarborenones A-F (1-6), were isolated from the leaves, twigs, and/or stem bark of Cratoxylum sumatranum along with the known compound, vismione B (9), as active constituents by bioassay-directed fractionation using the KB human cancer cell line cytotoxicity assay. In addition, two novel anthraquinobenzophenones, cratoxyarborequinones A (7) and B (8), and two known compounds, 2,4,6-trihydroxybenzophenone 4-O-geranyl ether and delta-tocotrienol, were obtained as inactive constituents.

The demand for new alternative sweeteners has increased due to certain health problems associated with the use of sucrose. Although the currently developed and commercially used sucrose substitutes are mostly synthetic compounds, the search for such compounds from natural sources is continuing and about 85 plant-derived sweetcompounds of 19 major structural types are known, which have been obtained from 25 different families of green plants. Some of these highly sweetnatural products are marketed as sweeteners or flavoring agents in several countries either as pure compounds or refined extracts. Several naturally occurring sweeteners have been chemically and enzymatically modified in order to increase their sweetness potency and/or improve their sweetness quality. In addition to natural sweet-tasting compounds, a number of naturally occurring sweetness-modifying compounds which induce or inhibit the sweet taste have also been isolated from plant sources. Several proteins and triterpenoids have sweetness-inducing properties. Over 60 triterpenoid glycosides have been reported from five plant species of the families Asclepidaceae and Rhamnaceae as sweetness-inhibitory (antisweet) principles.

Three pyrrolizidine alkaloids, symlandine, symphytine, and echimidine (1-3), were isolated from the roots of Symphytum officinale using a one-step countercurrent chromatography procedure. The structures of 1-3 were confirmed by several spectroscopic techniques including 2D NMR, methods. This is the first description of the separation of symlandine (1) from its stereoisomer, symphytine (2).

A new cinnamylphenol, macharistol (1), along with a known pterocarpan, (+)-medicarpin (2), were isolated as cytotoxic constituents from the stems of Machaerium aristulatum. In addition, a known pterocarpan, (+)-maackiain (3), and a known isoflavone, formononetin (4), were identified as inactive constituents. Compound 1 was evaluated in the in vivo hollow fiber assay with KB, Col-2, and hTERT-RPE1 cells and found to be inactive at the highest dose (25 mg/kg body weight) tested.

Abrusoside A methyl ester was prepared from abrusogenin through methylation (CH2N2) and a subsequent coupling reaction with 1-chloro-2,3,4,6-tetra-O-acethylglucopyranose in the presence of AgOTf and TMU in CH2Cl2, followed by deacetylation using K2CO3 in MeOH-H2O.

Four new triterpenoid glycosides were isolated from the root bark of Mussaenda macrophylla. Their structures were determined as 3-O-beta-D-glucopyranosyl-28-O-alpha-L-rhamnopyranosyl-16alpha- hydrox y-23-deoxyprotobassic acid (1), 28-O-beta-D-glucopyranosyl-16alpha-hydroxy-23-deoxyprotobassic+ ++ acid (2), 3-O-beta-D-glucopyranosyl-28-O-alpha-L-rhamnopyranosyl-16alpha- hydrox yprotobassic acid (3), and 3-O-¿[beta-D-glucopyranosyl-(1-->6)]-O-alpha-L-rhamnopyranosyl-(1-->2 )-O-beta-D-glucopyranosyl-(1-->2)¿-O-beta-D-glucopyranosyl-(1-->3)-O- beta-D-glucopyranosyl-cycloarta-22,24-dien-27-oic acid (mussaendoside W, 4). Four known triterpenoids [3-O-acetyloleanolic acid (5), 3-O-acetyldaturadiol (6), rotundic acid (7), and 16alpha-hydroxyprotobassic acid (8)] were also isolated. The structures of 1-4 were determined by several spectroscopic techniques including 2D NMR methods. Compounds 1-6 showed inhibitory activity against a periodontopathic bacterium, Porphyromonas gingivalis, but were inactive against the cariogenic organism, Streptococcus mutans.

In the search for new potently sweet compounds from plants, the rapid identification and quantification of free sugars and polyols in a crude plant extract is important for dereplication purposes, wherein compounds of known structure or biological activity are removed from further consideration, Accordingly, plants found to have high levels of free sugars and polyols are regarded as lower priority leads when screening for novel natural sweeteners, In the present study, gas chromatography-mass spectrometry was used to examine the sugar/polyol content of six sweet-tasting species, comprised of the pericarp of Dialium indum L. (Leguminosae), the stem of Drypetes floribunda Hutchinson (Euphorbiaceae), the fruit of Hymenaea oblongifolia Huber var, palustris (Ducke) Lee and Langenheim (Leguminosae), the rhizomes of Imperata cylindrica (L.) Beauvois (Gramineae), the fruit of Manilkara zapota (L.) van Royen (Sapotaceae), and the pericarp of Sapindus rarak DC, (Sapindaceae), The total yields of sugars/polyols in these plant parts were 1.9, 6.1, 7.8, 4.5, 10.8 and 2.9% w/w, respectively, Several uncommon polyols were identified, including bornesitol in D. floribunda and quebrachitol in S. rarak, It is likely that the sweet taste of the plants containing more than 5% of sugars/polyols is imparted as a result of the high free sugar and/or polyol content, Owing to its low level of free sugars, S. rarak pericarp was chosen for further study, and the known sesquiterpene glycoside mukurozioside IIb (1) was isolated in high yield (6.3% w/w) as a sweet-tasting constituent, Preliminary evaluations, comprised of mouse acute toxicity and bacterial mutagenesis determinations, indicated the safety of 1. The compound was subsequently rated by a human taste panel as having about the same sweetness potency as sucrose, (C) 1997 by John Wiley & Sons, Ltd.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.