Huaping Zhang

Anti-Arthritic Effects and Toxicity of the Essential Oils of Turmeric (Curcuma longa L.)

Turmeric (Curcuma longa L., Zingiberaceae) rhizomes contain two classes of secondary metabolites, curcuminoids and the less well-studied essential oils. Having previously identified potent anti-arthritic effects of the curcuminoids in turmeric extracts in an animal model of rheumatoid arthritis (RA), studies were undertaken to determine whether the turmeric essential oils (TEO) were also joint protective using the same experimental model. Crude or refined TEO extracts dramatically inhibited joint swelling (90-100% inhibition) in female rats with streptococcal cell wall (SCW)-induced arthritis when extracts were administered via intraperitoneal injection to maximize uniform delivery. However, this anti-arthritic effect was accompanied by significant morbidity and mortality. Oral administration of a 20-fold higher dose TEO was nontoxic, but only mildly joint-protective (20% inhibition). These results do not support the isolated use of TEO for arthritis treatment but, instead, identify potential safety concerns in vertebrates exposed to TEO.

Withaferin A, a cytotoxic steroid from Vassobia breviflora, induces apoptosis in human head and neck squamous cell carcinoma.

As part of a program to discover drug leads from plant biodiversity, the present investigation was undertaken to explore the anticancer potential of compounds derived from selected Latin American plants. Bioassay-guided fractionation of a crude extract of the aerial parts of Vassobia breviflora led to the isolation of the withanolide-type steroidal lactone withaferin A (1). This compound was tested for antiproliferative activity against the head and neck squamous cell carcinoma (HNSCC) cell lines, MDA1986, JMAR, UM-SCC-2, and JHU011. The inhibitory concentrations to reduce cell viability to 50% (IC(50)) were determined by the MTS cytotoxicity assay, and 1 reduced cell viability with IC(50) values in the range 0.5-2.2 μM. A mechanistic study showed that 1 induces apoptosis and cell death in HNSCC cells as well as a cell-cycle shift from G(0)/G(1) to G(2)/M. Cells treated with 1 exhibited inactivation of Akt and a reduction in total Akt concentration. This investigation constitutes the first report of the antiproliferative activity of withaferin A (1) against head and neck squamous carcinoma.

Cytotoxicity of withaferin A in glioblastomas involves induction of an oxidative stress-mediated heat shock response while altering Akt/mTOR and MAPK signaling pathways.

SummaryWithaferin A (WA), a steroidal lactone derived from the plant Vassobia breviflora, has been reported to have anti-proliferative, pro-apoptotic, and anti-angiogenic properties against cancer growth. In this study, we identified several key underlying mechanisms of anticancer action of WA in glioblastoma cells. WA was found to inhibit proliferation by inducing a dose-dependent G2/M cell cycle arrest and promoting cell death through both intrinsic and extrinsic apoptotic pathways. This was accompanied by an inhibitory shift in the Akt/mTOR signaling pathway which included diminished expression and/or phosphorylation of Akt, mTOR, p70 S6K, and p85 S6K with increased activation of AMPKα and the tumor suppressor tuberin/TSC2. Alterations in proteins of the MAPK pathway and cell surface receptors like EGFR, Her2/ErbB2, and c-Met were also observed. WA induced an N-acetyl-L-cysteine-repressible enhancement in cellular oxidative potential/stress with subsequent induction of a heat shock stress response primarily through HSP70, HSP32, and HSP27 upregulation and HSF1 downregulation. Taken together, we suggest that WA may represent a promising chemotherapeutic candidate in glioblastoma therapy warranting further translational evaluation.

Cytotoxic withanolide constituents of Physalis longifolia.

Fourteen new withanolides, 1-14, named withalongolides A-N, respectively, were isolated from the aerial parts of Physalis longifolia together with eight known compounds (15-22). The structures of compounds 1-14 were elucidated through spectroscopic techniques and chemical methods. In addition, the structures of withanolides 1, 2, 3, and 6 were confirmed by X-ray crystallographic analysis. Using a MTS viability assay, eight withanolides (1, 2, 3, 7, 8, 15, 16, and 19) and four acetylated derivatives (1a, 1b, 2a, and 2b) showed potent cytotoxicity against human head and neck squamous cell carcinoma (JMAR and MDA-1986), melanoma (B16F10 and SKMEL-28), and normal fetal fibroblast (MRC-5) cells with IC₅₀ values in the range between 0.067 and 9.3 μM.

Antiproliferative withanolides from the Solanaceae: A structure–activity study

As part of our search for bioactive compounds from plant biodiversity, 29 withanolides were recently isolated from three members of the Solanaceae: Physalis longifolia, Vassobia breviflora, and Withania somnifera. Six derivatives were prepared from these naturally occurring withanolides. All compounds were evaluated for in vitro antiproliferative activity against an array of cell lines [melanoma cell lines (B16F10, SKMEL28); human head and neck squamous cell carcinomas (HNSCC) cell lines (JMAR, MDA1986, DR081-1); breast cancer cell line (Hs578T), and non-malignant human cell line (MRC5)]. This led to the discovery of 15 withanolides, with IC50 values in the range of 0.067−17.4 μM, including withaferin A, withaferin A 4,27-diacetate, 27-O-glucopyranosylwithaferin A, withalongolide H, withalongolide C, withalongolide A, withalongolide A 4,27-diacetate, withalongolide A 4,19,27-triacetate, withalongolide B, withalongolide B 4-acetate, withalongolide B 4,19-diacetate, withalongolide D, withalongolide E, withalongolide G, and 2,3-dihydrowithaferin A 3-O-sulfate. In order to update the growing literature on withanolides and their activities, we summarized the distribution, structural types, and antiproliferative activities for all published withanolides to date. The structure–activity relationship analysis (SARA) confirmed the importance of the presence of a ∆2-1-oxo-functionality in ring A, a 5β,6β-epoxy or 5α-chloro-6β-hydroxy grouping in ring B, and nine-carbon side chain with a lactone moiety for cytotoxic activity. Conversely, the SARA indicated that the –OH or –OR groups at C-4, 7, 11, 12, 14, 15, 16, 17, 18, 19, 20, 23, 24, 27, and 28 were not contributors to the observed antiproliferative activity within the systems analyzed.

Cytotoxic oleanane-type saponins from Albizia inundata

Bioassay-guided fractionation of a CH(2)Cl(2)-MeOH extract of the aerial parts of Albizia inundata resulted in the isolation of two new natural oleanane-type triterpene saponins {3-O-[α-L-arabinopyranosyl(1→6)]-2-acetamido-2-deoxy-β-D-glucopyranosyl oleanolic acid (1) and 3-O-[α-L-arabinopyranosyl(1→2)-α-L-arabinopyranosyl(1→6)]-2-acetamido-2-deoxy-β-D-glucopyranosyl acacic acid lactone (2)} along with seven known saponins {3-O-[α-L-arabinopyranosyl(1→6)]-2-acetamido-2-deoxy-β-D-glucopyranosyl echinocystic acid (3), 3-O-[β-D-xylopyranosyl (l→2)-α-L-arabinopyranosyl(l→6)]-2-acetamido-2-deoxy-β-D-glucopyranosyl acacic acid lactone (concinnoside D) (4), 3-O-[β-D-glucopyranosyl(l→2)]-β-D-glucopyranosyl oleanolic acid (5), 3-O-[α-L-arabinopyranosyl(1→2)-α-L-arabinopyranosyl(l→6)]-β-D-glucopyranosyl oleanolic acid (6), 3-O-[β-D-xylopyranosyl(1→2)-α-L-arabinopyranosyl(l→6)]-β-D-glucopyranosyl oleanolic acid (7), 3-O-[α-L-arabinopyranosyl(l→2)-α-L-arabinopyranosyl(1→6)-[β-D-glucopyranosyl(l→2)]-β-D-glucopyranoside echinocystic acid (8), and 3-O-[β-D-xylopyranosyl(l→2)-α-L-arabinopyranosyl(1→6)-[β-D-glucopyranosyl(l→2)]-β-D-glucopyranoside echinocystic acid (9)}. The structures of 1 and 2 were established on the basis of extensive 2D NMR ((1)H-(1)H COSY or DQF-COSY, HSQC, HMBC, TOCSY, and HSQC-TOCSY) spectroscopic, ESIMS, and chemical methods. Saponins 1, 3, 6, and 7 showed cytotoxicity against human head and neck squamous cells (JMAR, MDA1986) and melanoma cells (B16F10, SKMEL28) with IC(50) values in the range 1.8-12.4 μM, using the MTS assay.

Antiproliferative withanolides from several solanaceous species.

To date, our work on solanaceous species (Datura wrightii, Jaborosa caulescens, Physalis hispida, Physalis longifolia, Vassobia breviflora and Withania somnifera) has resulted in the isolation of 65 withanolides, 31 of which were new, as well as the semi-synthesis of a further 30 withanolides. Structure identification and MTS assay-based antiproliferative evaluation of these 95 compounds revealed that a Δ2-1-oxo functionality in ring A, in conjunction with either a 5β,6β-epoxy or 5α-chloro-6β-hydroxy moiety in ring B, is the minimum structural requirement for withanolides to produce potent cytotoxic activity. Such structure–activity relationship analysis also revealed that oxygenation (the –OH or –OR groups) at C-4, 7, 11 and 12, as well as C-14 to C-28, did not contribute towards the observed antiproliferative activity. Herein, we present a complete overview of our work as it relates to the withanolides reported from 1965 to 2013.

Withanolides from Physalis hispida

Nine new withanolides (1-9), withahisolides A-I, were isolated along with nine known compounds (10-18) from the aerial parts of Physalis hispida. The structures of 1-9 were elucidated through a variety of spectroscopic techniques, while the structures of 1 and 2 were confirmed by X-ray crystallographic analysis. Compounds 1-3 are the first withanolides with nonaromatic six-membered ring D moieties. In addition, withanolide 8 represents a novel withanolide skeleton due to the absence of a C-13-C-17 bond within the steroidal nucleus.

Antiproliferative withanolides from Datura wrightii.

A new withanolide, named withawrightolide (1), and four known withanolides (2-5) were isolated from the aerial parts of Datura wrightii. The structure of compound 1 was elucidated through 2D NMR and other spectroscopic techniques. In addition, the structure of withametelin L (2) was confirmed by X-ray crystallographic analysis. Using MTS viability assays, withanolides 1-5 showed antiproliferative activities against human glioblastoma (U251 and U87), head and neck squamous cell carcinoma (MDA-1986), and normal fetal lung fibroblast (MRC-5) cells with IC50 values in the range between 0.56 and 5.6 μM.

Novel HSP90 inhibitors effectively target functions of thyroid cancer stem cell preventing migration and invasion

BACKGROUND Thyroid cancer stem cells (CSCs) with ALDH and CD44 markers contribute to tumor growth and aggressiveness. We hypothesized that novel HSP90 inhibitors (KU711, WGA-TA) and 17-AAG can effectively target the function of thyroid CSCs in vitro and prevent migration and invasion. METHODS Validated papillary (TPC1), follicular (FTC238,WRO), and anaplastic (ACT1) human thyroid cancer cell lines were treated with 3 HSP90 inhibitors. CSCs were quantified for aldehyde dehydrogenase by flow cytometry, CD44 expression by Western blot, and thyrosphere formation assay. Cellular pathway proteins were analyzed by Western blot and migration/invasion by Boyden-chambers. RESULTS WGA-TA and 17-AAG induced HSP70 compensation (not observed with KU711) on Western blot in all cell lines (>1,000 fold vs controls). Only WGA-TA degraded HSP90-Cdc37 complexing by 60-70% versus controls. Expression of HSP90 clients β-catenin, BRAF, Akt, and phospho-Akt were significantly inhibited by WGA-TA treatment (50-80%, 50-90%, >80%, and >90%) compared with controls, KU711, and 17-AAG treatment. KU711 and WGA-TA decreased CD44 expression in all cell lines (25-60% vs controls/17-AAG), decreased ALDEFLOR activity by 69-98% (P < .005), and decreased sphere formation by 64-99% (P < .05 each). Finally, cell migration was decreased by 31-98%, 100%, and 30-38%, and invasion by 75-100%, 100%, and 47% by KU711,WGA-TA, and 17-AAG treatment (P < .05) each, respectively. CONCLUSION KU711 and WGA-TA are novel HSP90 inhibitors targeting CSC function and inhibiting cell migration/invasion in differentiated and anaplastic thyroid cancers, warranting further translational evaluation in vivo.