Recent progress of research on medicinal mushrooms, foods, and other herbal products used in traditional Chinese medicine.

This article will review selected herbal products used in traditional Chinese medicine, including medicinal mushrooms ( ba xi mó gu; Agaricus blazei, yún zhi; Coriolus versicolor, líng zhi; Ganoderma lucidum, xiang xùn; shiitake, Lentinus edodes, niú zhang zhi; Taiwanofungus camphoratus), Cordyceps ( dong chóng xià cǎo), pomegranate ( shí liú; Granati Fructus), green tea ( lǜ chá; Theae Folium Non Fermentatum), garlic ( dà suàn; Allii Sativi Bulbus), turmeric ( jiang huáng; Curcumae Longae Rhizoma), and Artemisiae Annuae Herba ( qing hao; sweet wormwood). Many of the discussed herbal products have gained popularity in their uses as dietary supplements for health benefits. The review will focus on the active constituents of the herbs and their bioactivities, with emphasis on the most recent progress in research for the period of 2003 to 2011.

Recent advances in the investigation of curcuminoids.

More than 30 Curcuma species (Zingiberaceae) are found in Asia, where the rhizomes of these plants are used as both food and medicine, such as in traditional Chinese medicine. The plants are usually aromatic and carminative, and are used to treat indigestion, hepatitis, jaundice, diabetes, atherosclerosis and bacterial infections. Among the Curcuma species, C. longa, C. aromatica and C. xanthorrhiza are popular. The main constituents of Curcuma species are curcuminoids and bisabolane-type sesquiterpenes. Curcumin is the most important constituent among natural curcuminoids found in these plants. Published research has described the biological effects and chemistry of curcumin. Curcumin derivatives have been evaluated for bioactivity and structure-activity relationships (SAR). In this article, we review the literature between 1976 and mid-2008 on the anti-inflammatory, anti-oxidant, anti-HIV, chemopreventive and anti-prostate cancer effects of curcuminoids. Recent studies on curcuminoids, particularly on curcumin, have discovered not only much on the therapeutic activities, but also on mechanisms of molecular biological action and major genomic effects.

5-Hydroxymethyl-2-furfural, a clinical trials agent for sickle cell anemia, and its mono/di-glucosides from classically processed steamed Rehmanniae Radix.

Rehmanniae Radix (Di Huang) is one of the most important traditional Chinese medicines (TCM), and is used for multiple therapeutic purposes. In our investigation of the chemical constituents of Rehmanniae Radix, steamed roots were prepared by the classical processing method. Reversed-phase HPLC of the 50% MeOH extract of steamed Rehmanniae Radix yielded three 5-hydroxymethylfurfural derivatives. The new furfural disaccharide 5-(alpha-D-glucopyranosyl-(1-->6)-alpha-D-glucopyranosyloxymethyl)-2-furancarboxaldehyde (1) was isolated and characterized, together with its known aglycone 5-hydroxymethyl-2-furfural (3), which is currently in sickle cell anemia Phase I clinical trials, and its corresponding monosaccharide 5-(alpha-D-glucopyranosyloxymethyl)-2-furancarboxaldehyde (2), which was isolated as a natural product for the first time. The presence of these three compounds, particularly 3, which were not found in the unprocessed extract of Rehmanniae Radix, could substantiate the traditional medicinal use of steamed Rehmanniae Radix.

Plant-derived natural product research aimed at new drug discovery.

Many important bioactive compounds have been discovered from natural sources using bioactivity-directed fractionation and isolation (BDFl) [Balunas MJ, Kinghorn AD (2005) Drug discovery from medicinal plants. Life Sci 78:431-441]. Continuing discovery has also been facilitated by the recent development of new bioassay methods. These bioactive compounds are mostly plant secondary metabolites, and many naturally occurring pure compounds have become medicines, dietary supplements, and other useful commercial products. Active lead compounds can also be further modified to enhance the biological profiles and developed as clinical trial candidates. In this review, the authors will summarize research on many different useful compounds isolated or developed from plants with emphasis placed on those recently discovered by the authors' laboratories as antitumor and anti-HIV clinical trial candidates.

Antitumor agents. 261. 20(S)-protopanaxadiol and 20(s)-protopanaxatriol as antiangiogenic agents and total assignment of (1)H NMR spectra.

Angiogenesis is a critical step in tumor progression and involves several steps including endothelial cell (EC) proliferation, migration, and matrix remodeling. We investigated the antiangiogenic effects of 20( S)-protopanaxadiol ( 1) and 20( S)-protopanaxatriol ( 2), the sapogenins of two major ginseng saponins, in an angiogenesis model of human umbilical vein endothelial cells (HUVECs). These compounds inhibited the proliferative activity of HUVECs in a dose-dependent manner and have potential as anticancer drug candidates. In addition, we report the complete and unambiguous assignment of (1)H NMR spectra of 1 and 2, based on analyses of 2D NMR spectra including COSY, NOESY, HSQC, and HMBC. This report is the first to completely assign the (1)H NMR signals of 2, together with correction of data for 1 from prior reports.

Separation and characterization of active flavonolignans of Silybum marianum by liquid chromatography connected with hybrid ion-trap and time-of-flight mass spectrometry (LC-MS/IT-TOF).

Silychristins A (1) and B (2), silydianin (3), silybins A (4) and B (5), and isosilybins A (6) and B (7) are major bioactive flavonolignans in silymarin, a herbal remedy derived from the milk thistle Silybum marianum. In this study, the seven major active flavonolignans including the diastereomers 1/ 2, 4/ 5, and 6/ 7 were completely separated using semi-micro-high performance liquid chromatography (HPLC) with a Nucleosil 100-3 C 18 HD column and a MeOH/water/formic acid mobile phase system. The collision-induced dissociation (CID) MS/MS and MS (3) spectra of these flavonolignans were studied systematically using hybrid ion-trap and time-of-flight (IT-TOF) mass spectrometry. Efficient differentiation between the seven flavonolignans (1- 7) was possible based on comparison of the resultant CID-MS/MS or MS (3) spectra. Each characteristic MS/MS or MS (3) fragmentation pattern was elucidated with high-resolution mass spectra by IT-TOF. The results with the present methodology show that liquid chromatography-mass spectrometry IT-TOF (LC-MS/IT-TOF) can be useful for general screening of active natural products from plant extracts and for the specific quality control of silymarin.

Anti-tumor agents 255: novel glycyrrhetinic acid-dehydrozingerone conjugates as cytotoxic agents.

Esterification of glycyrrhetinic acid (GA) with dehydrozingerone (DZ) resulted in a novel cytotoxic GA-DZ conjugate. Based on this exciting finding, we conjugated eleven different DZ analogs with GA or other triterpenoids, including oleanoic acid (OA) or ursolic acid (UA). In an in vitro anti-cancer assay using nine different human tumor cell lines, most of the GA-DZ conjugates showed significant potency. Particularly, compounds 5, 29, and 30 showed significant cytotoxic effects against LN-Cap, 1A9, and KB cells with ED(50) values of 0.6, 0.8, and 0.9 microM, respectively. Similar conjugates between DZ and OA or UA were inactive suggesting that the GA component is critical for activity. Notably, although GA-DZ conjugates showed potent cytotoxic activity, the individual components (GA and DZ analogs) were inactive. Thus, GA-DZ conjugates are new chemical entities and represent interesting hits for anti-cancer drug discovery and development.

Dehydrozingerone, chalcone, and isoeugenol analogues as in vitro anticancer agents.

Twenty-eight compounds related to dehydrozingerone (1), isoeugenol (3), and 2-hydroxychalcone (4) were synthesized and evaluated in vitro against human tumor cell replication. Except for isoeugenol analogues 27-35, most compounds exhibited moderate or strong cytotoxic activity against KB, KB-VCR (a multidrug-resistant derivative), and A549 cell lines. In particular, chalcone 15 showed significant cytotoxic activity against the A549 cell line with an IC50 value of 0.6 microg/mL. Furthermore, dehydrozingerone analogue 11 and chalcones 16 and 17 showed significant and similar cytotoxic activity against both KB (IC50 values of 2.0, 1.0, and 2.0 microg/mL, respectively) and KB-VCR (IC50 values of 1.9, 1.0, and 2.0 microg/mL, respectively) cells, suggesting that they are not substrates for the P-glycoprotein drug efflux pump.

Structure of a new cyclic nonapeptide, segetalin F, and vasorelaxant activity of segetalins from Vaccaria segetalis.

A new cyclic nonapeptide, segetalin F, has been isolated from the seeds of Vaccaria segetalis and the structure including absolute stereochemistry was elucidated by using 2D NMR and chemical means. A series of segetalins showed a vasorelaxant activity against norepinephrine (NE)-induced contractions of rat aorta.

Cycloleonuripeptides E and F, cyclic nonapeptides from Leonurus heterophyllus.

Two new cyclic nonapeptides, cycloleonuripeptide E, cyclo (-Ala-Pro-Ile-Val-Ala-Ala-Phe-Thr-Pro-), and cycloleonuripeptide F, cyclo (-Gly-Tyr-Pro-Leu-Pro-Phe-Tyr-Pro-Pro-), have been isolated from the fruits of Leonurus heterophyllus, and their structures were elucidated by 2D NMR analysis and chemical degradation. Cycloleonuripeptides E (1) and F (2) showed moderate vasorelaxant effects on rat aorta.

Dichotomins J and K, vasodilator cyclic peptides from Stellaria dichotoma.

Two new cyclic peptides, dichotomins J (1) and K (2), have been isolated from the roots of Stellaria dichotoma, and their structures were elucidated by chemical degradation and extensive 2D NMR methods. Dichotomins J (1) and K (2) showed a moderate vasorelaxant effect on rat aorta.

Conformational analysis of rhazinilam and three-dimensional quantitative structure-activity relationships of rhazinilam analogues.

3D QSAR of rhazinilam (1), an alkaloid isolated from Rhazya stricta (Apocynaceae) with an activity involving disassembly of microtubules and its derivatives was investigated by using the comparative molecular field analysis (CoMFA). In an effort to get a better understanding of the correlation between conformation and antitubulin activity of 1, most probable minimum energy conformation in solution of 1 was analyzed on the basis of NMR data of 1 in solution. The results indicated a correlation between the antitubulin activity of these alkaloids and the steric and electrostatic factors, which modulate their biological activity, and accounted for the potent activities of 1 with suitable relationship for the overall conformation.

Two cangorosin A type triterpene dimers from Maytenus chuchuhuasca.

Two new cangorosin A type triterpene dimers, which composed of two triterpene units jointed by two ether linkages between the A and B rings, were isolated from the Brazilian medicinal plant "xuxuá" (Maytenus chuchuhuasca). Structures of new isolates, xuxuasins A (1) and B (2), were established based on several spectroscopic evidences.

Nine regioisomeric and stereoisomeric triterpene dimers from Maytenus chuchuhuasca.

Nine regioisomeric and stereoisomeric triterpene dimers, namely xuxuarine Falpha (1), isoxuxuarine Falpha (2; cangorosin B), 7,8-dihydroisoxuxuarine Falpha (3), isoxuxuarine Gbeta (4), 7,8-dihydroisoxuxuarine Galpha (5), isoxuxuarine Ebeta (6), 7alpha-hydroxyisoxuxuarine Ealpha (7), 7',8'-dihydroxuxuarine Aalpha (8), and 7',8'-dihydroxuxuarine Dbeta (9), were isolated from the Brazilian medicinal plant "xuxuá" (Maytenus chuchuhuasca). Their structures have been elucidated based on several spectroscopic analyses including 2D-NMR experiments, MS spectra and CD spectral studies.

Synthesis of [Gly-1]RA-VII, [Gly-2]RA-VII, and [Gly-4]RA-VII. Glycine-containing analogues of RA-VII, an antitumor bicyclic hexapeptide from Rubia plants.

Three analogues of RA-VII (1), an antitumor bicyclic hexapeptide from Rubia plants, were synthesized. Three analogues, [Gly-1]RA-VII (4), [Gly-2]RA-VII (5), and [Gly-4]RA-VII (6), in which one of the three alanine residues in 1 was replaced by a glycine residue, were prepared by linking of the cycloisodityrosine unit, obtained by degradation of 1, to three different glycine-containing tetrapeptides followed by macrocyclization. Of these three analogues, analogue 4 showed the highest cytotoxic activity. The NMR study revealed that in solution the conformer structures and their ratios of analogue 4 were very similar to those of natural peptide 1, suggesting that the methyl groups at Ala-2 and Ala-4 should be essential for producing the bioactive conformation, whereas that at D-Ala-1 is not essential.

Anti-AIDS agents. Part 57: Actein, an anti-HIV principle from the rhizome of Cimicifuga racemosa (black cohosh), and the anti-HIV activity of related saponins.

Actein (1), a tetracyclic triterpenoid from the rhizome of Cimicifuga racemosa (black cohosh), and 82 related triterpenoid and steroidal saponins isolated from higher plants were evaluated for anti-HIV activity as a continuing study to discover potential anti-AIDS agents from natural products. Actein showed potent activity and another twelve saponins showed moderate activity. The active compounds included two steroidal, seven tetracyclic triterpenoid, and four pentacyclic triterpenoid compounds.

Nine new isoxuxuarine-type triterpene dimers from Maytenus chuchuhuasca.

Nine new isoxuxuarine-type triterpene dimers, named isoxuxuarines B alpha (1), B beta (2), 7,8-dihydro-B alpha (3), C alpha (4), C beta (5), 7,8-dihydro-C alpha (6), D alpha (7), D beta (8), and 7,8-dihydro-D alpha (9), were isolated from the South American medicinal plant 'xuxuá' (Maytenus chuchuhuasca). The structures were elucidated on the basis of several spectroscopic analyses, including 2D-NMR experiments, MS spectra, and CD spectral studies. The isolations and structure elucidations of the new triterpene dimers are presented, and a rationale for the divergent formation of the regiochemical and stereochemical isomers of triterpene dimers is discussed.

Antitumor agents 222. Synthesis and anti-androgen activity of new diarylheptanoids.

Fifteen new diarylheptanoids were synthesized and evaluated for antagonistic activity against androgen receptor (AR)-mediated reporter gene transcription using DU145, PC-3, and LNCaP prostate cancer cell lines. Most compounds showed activity in a 5alpha-dihydrotestosterone (DHT)-induced reporter gene expression assay in DU145 cells transfected with wild-type AR. Ten compounds (5, 8, 10, 14-15, and 18-22) were equipotent with hydroxyflutamide (HF), the anti-androgen currently available for the treatment of prostate cancer. However, except for compounds 5 and 10, none of the tested compounds was significantly effective in attenuating DHT-induced reporter gene expression in LNCaP cells, which contain endogenous mutant AR.

Synthesis of [L-Ala-1]RA-VII, [D-Ala-2]RA-VII, and [D-Ala-4]RA-VII by epimerization of RA-VII, an antitumor bicyclic hexapeptide from Rubia plants, through oxazoles.

Three epimers of a natural cyclic hexapeptide RA-VII were prepared via formation of oxazoles from thioamides or thioimidates of RA-VII followed by hydrolysis. They are the epimers at l-Ala-1, d-Ala-2, and d-Ala-4, respectively. The one having l-Ala-1 adopted trans-cis-trans-trans-trans-trans (t-c-t-t-t-t) amide configurations in the crystal, a type-VI beta-turn for residues 1-4 stabilized by one intramolecular hydrogen bond between Ala-4 NH and l-Ala-1 C = O, and in CDCl(3) existed as a mixture of six conformers, of which the major conformer was very similar to that in the crystal, but quite different from that of RA-VII in solution. The second epimer, having d-Ala-2 had in the crystalline state t-t-t-t-c-t amide configurations, a gamma-turn at Tyr-3 stabilized by two intramolecular hydrogen bonds between d-Ala-2 NH and Ala-4 C = O and between Ala-4 NH and d-Ala-2 C = O, and existed in CDCl(3) as a single conformer, the structure of which was very similar to its crystal structure, and to the crystal structure of peptide 25 except for the backbone and the side chains at residues 1 and 2. The third epimer, having d-Ala-4 had t-c-t-t-c-t amide configurations in the crystal, a type-VI beta-turn for residues 1-4 as observed in the first epimer, and in CDCl(3) existed in three conformers, of which the major one was similar to that in the crystal but different from that of RA-VII in solution. The three epimers showed very weak cytotoxicity on P-388 leukemia cells, which may be because of their conformational differences from the active conformation of RA-VII.

QSAR evaluation of the Ch'an Su and related bufadienolides against the colchicine-resistant primary liver carcinoma cell line PLC/PRF/5(1).

QSAR analysis has been used to identify the essential structural requirements for increasing the inhibitory activities of selected bufadienolides from the Chinese drug Ch'an Su (and other sources) against the primary liver carcinoma cell line PLC/PRF/5 (PLC) and the derived colchicine-resistant line (COL). The variable substituent domain of the proposed pharmacophore of the bufadienolides was investigated using a Comparative Molecular Field Analysis (CoMFA) approach. A model with considerable predictive ability was obtained. In addition, the CoMFA results agreed well with the pharmacophore bufadienolide model for the parent PLC line proposed earlier.