The potential of achiral sponge-derived and synthetic bromoindoles as selective cytotoxins against PANC-1 tumor cells.

Our quest to isolate and characterize natural products with in vitro solid tumor selectivity is driven by access to repositories of Indo-Pacific sponge extracts. In this project an extract of a species of Haplosclerida sponge obtained from the US NCI Natural Products Repository displayed, by in vitro disk diffusion assay (DDA) and I

Development and Validation of a Simple Method for the Detection of Fascaplysin in Plasma

Fascaplysin is a cytotoxic natural product isolated from a variety of Indo-Pacific marine organisms, primarily Fascaplysinopsis sponges and Didemnum tunicates. Positive xenograft studies involving this alkaloid structural class have indicated that fascaplysin may serve as an important lead compound for preclinical development. This study was undertaken as a prelude to a full pharmacokinetics and therapeutic assessment of fascaplysin. We describe here a simple plasma preparation and a rapid HPLC method for the detection of fascaplysin in mice. The method was validated by parameters including good linear correlation, a limit of quantification of 107.1 μg/ mL, and a good precision with a coefficient of variation of 0.92% for 10 μg/mL. This method provides excellent sensitivity and visualization of fascaplysin as a single peak allowing for rapid analysis of plasma samples involving absorption, distribution, and metabolism studies. A preliminary pharmacokinetics study in C57Bl/6 mice using 20.6 mg/kg fascaplysin yielded a biphasic curve with T½α=16.7 min, T½β=11.7 h, and C0 of 17.1 μg/mL

HPLC Plasma Assay of a Novel Anti-MRSA Compound, Kaempferol-3-O-Alpha-L-(2 \u27\u27,3 \u27\u27-di-p-coumaroyl)rhamnoside, from Sycamore Leaves

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious pathogen that is resistant to current antibiotic therapy. Thus, there is an urgent need for novel antimicrobial agents that can effectively combat these new strains of drug-resistant superbugs . Recently, fractionation of an extract from Platanus occidentalis (American sycamore) leaves produced an active kaempferol molecule, 3-O-alpha-L-(2 ,3 -di-p-coumaroyl)rhamnoside (KCR), in four isomeric forms; all four isomers exhibit potent anti-MRSA activity. In order to further the preclinical development of KCR as a new antibiotic class, we developed and validated a simple analytical method for assaying KCR plasma concentration. Because KCR will be developed as a new drug, although comprising four stereoisomers, the analytical method was devised to assay the total amount of all four isomers. In the present work, both a plasma processing procedure and an HPLC method have been developed and validated. Mouse plasma containing KCR was first treated with ethanol and then centrifuged. The supernatant was dried, suspended in ethanol, centrifuged, and the supernatant was injected into an HPLC system comprising a Waters C18, a mobile phase composing methanol, acetonitrile, and trifluoroacetic acid and monitored at 313 nm. The method was validated by parameters including a good linear correlation, a limit of quantification of 0.27 μg/mL, and high accuracy. In summary, this method allows a rapid analysis of KCR in the plasma samples for pharmacokinetics studies

Myxobacteria versus sponge-derived alkaloids: the bengamide family identified as potent immune modulating agents by scrutiny of LC-MS/ELSD libraries.

A nuclear factor-κB (NF-κB) luciferase assay has been employed to identify the bengamides, previously known for their anti-tumor activity, as a new class of immune modulators. A unique element of this study was that the bengamide analogs were isolated from two disparate sources, Myxococcus virescens (bacterium) and Jaspis coriacea (sponge). Comparative LC-MS/ELSD and NMR analysis facilitated the isolation of M. viriscens derived samples of bengamide E (8) and two congeners, bengamide E\u27 (13) and F\u27 (14) each isolated as an insperable mixture of diastereomers. Additional compounds drawn from the UC, Santa Cruz repository allowed expansion of the structure activity relationship (SAR) studies. The activity patterns observed for bengamide A (6), B (7), E (8), F (9), LAF 389 (12) and 13-14 gave rise to the following observations and conclusions. Compounds 6 and 7 display potent inhibition of NF-κB (at 80 and 90 nM, respectively) without cytotoxicity to RAW264.7 macrophage immune cells. Western blot and qPCR analysis indicated that 6 and 7 reduce the phosphorylation of IκBα and the LPS-induced expression of the pro-inflammatory cytokines/chemokines TNFα, IL-6 and MCP-1 but do not effect NO production or the expression of iNOS. These results suggest that the bengamides may serve as therapeutic leads for the treatment of diseases involving inflammation, that their anti-tumor activity can in part be attributed to their ability to serve as immune modulating agents, and that their therapeutic potential against cancer merits further consideration

Another Look at Pyrroloiminoquinone Alkaloids-Perspectives on Their Therapeutic Potential from Known Structures and Semisynthetic Analogues

This study began with the goal of identifying constituents from Zyzzya fuliginosa extracts that showed selectivity in our primary cytotoxicity screen against the PANC-1 tumor cell line. During the course of this project, which focused on six Z. fuliginosa samples collected from various regions of the Indo-Pacific, known compounds were obtained consisting of nine makaluvamine and three damirone analogues. Four new acetylated derivatives were also prepared. High-accuracy electrospray ionization mass spectrometry (HAESI-MS) m/z ions produced through MS² runs were obtained and interpreted to provide a rapid way for dereplicating isomers containing a pyrrolo[4,3,2-de]quinoline core. In vitro human pancreas/duct epithelioid carcinoma (PANC-1) cell line IC50 data was obtained for 16 compounds and two therapeutic standards. These results along with data gleaned from the literature provided useful structure activity relationship conclusions. Three structural motifs proved to be important in maximizing potency against PANC-1: (i) conjugation within the core of the ABC-ring; (ii) the presence of a positive charge in the C-ring; and (iii) inclusion of a 4-ethyl phenol or 4-ethyl phenol acetate substituent off the B-ring. Two compounds, makaluvamine J (9) and 15-O-acetyl makaluvamine J (15), contained all three of these frameworks and exhibited the best potency with IC50 values of 54 nM and 81 nM, respectively. These two most potent analogs were then tested against the OVCAR-5 cell line and the presence of the acetyl group increased the potency 14-fold from that of 9 whose IC50 = 120 nM vs. that of 15 having IC50 = 8.6 nM

Development and validation of a rapid method for the detection of latrunculol A in plasma

Latrunculol A is a recently discovered 6,7-dihydroxy analog of the potent actin inhibitor latrunculin A. Latrunculol A has exhibited greater cytotoxicity than latrunculin A against both murine and human colon tumor cell lines in vitro. Currently, there are no reports regarding the bioavailability of latrunculol A in vivo. This study was undertaken as a prelude to pharmacokinetic assessments and it is the first work where bioavailability of latrunculol A was studied. In the present work, a simple plasma preparation and a rapid HPLC method have been developed. Mouse plasma containing latrunculol A was first treated by acetonitrile and then centrifuged at 14,000 rpm at 4 °C for 25 min. The supernatant was injected in an HPLC system comprising a Waters Symmetry NH2 column, a mobile phase of acetonitrile/water (95/5, v/v), a flow rate of 1.0 mL/min, at 220 nm. The method was validated by parameters including a good linear correlation, a limit of quantification of 9 ng/mL, and a good precision with a coefficient variation of 1.65, 1.86, and 1.26% for 20, 400, and 800 ng/mL, respectively. With this simple method, excellent separation and sensitivity of latrunculol A are achieved, thus allowing a rapid analysis of the plasma samples for absorption, distribution, and metabolism studies

Synthesis and Biological Evaluation of Novel N-phenyl-5-carboxamidyl Isoxazoles as Potential Chemotherapeutic Agents for Colon Cancer

Abstract A new series of isoxazole derivatives, N-phenyl-5-carboxamidyl isoxazoles, was investigated for their anticancer activity with solid tumor selectivity. Six N-phenyl-5-carboxamidylisoxazoles were chemically synthesized and evaluated by the in vitro disk-diffusion assay and IC 50 cytotoxicity determination. The results showed that one of the derivatives, compound 3, N-(4-chlorophenyl)-5-carboxamidyl isoxazole, was the most active against colon 38 and CT-26 mouse colon tumor cells with an IC 50 of 2.5 µg/mL for both cell lines. Western blot analysis showed that compound 3 significantly down-regulated the expression of phosphorylated STAT3 in both human and mouse colon cancer cells indicating that the mechanism of action for compound 3 may involve the inhibition of JAK3/STAT3 signaling pathways. Flow cytometric analysis with Annexin V staining showed that the death induced by compound 3 is mediated through cell necrosis and not apoptotic pathway. In summary, our results show that compound 3 is a new N-phenyl-5-carboxamidyl isoxazole with potential anticancer activity. Compound 3 inhibits the phosphorylation of STAT3, a novel target for chemotherapeutic drugs, and is worthy of further investigation as a potential chemotherapeutic agent for treating colon cancer

Arctin and Arctigenin as a Potential Treatment for Solid Tumors

Arctigenin (AR) and its glucoside arctiin are two major active ingredients of the lignin-containing plant Arctium lappa. Traditional Chinese Medicine has demonstrated the utility of these lignin-containing compounds for a wide spectrum of activity. These compounds have been shown to possess various biological activities like antiinflammatory, anti-viral, and anti-cancer activity. Our interest in arctiin/AR relates to their antiproliferative/antitumor activity. The studies conducted in the past have not been structured in a well-defined manner for anti-cancer potential. We focused on the anti-tumor activity of these compounds against a set of human solid tumor cell lines (Pancreatic-PANC-1, colon-H116, lung-H125, liver- HepG2, OVC-5 and brain-U251N). Further, our study is based on our developmental paradigm; determination of the IC50 value; an in vitro clonogenic assessment of the drug as a function of both concentration and duration of exposure; preparation of an intravenous formulation of the drug followed by a determination of the maximum tolerated dose. To carry out our study, we first did an in-vitro disk diffusion assay which defines the differential cell killing against the solid tumor cell lines examined. When compared with murine CFU-GM and human leukemia CEM; we found that arctiin and AR were selective against H116, PANC-1, HepG2 and U251N cell lines. Following this, IC-50 determinations were performed against H116 and we found that IC50 values were 2.5μg/ml for arctiin and 0.31μg/ml for AR. Colonogenic (colony forming) studies were done for these compounds for H116 cell line at 2 hr, 24hr and 7days. The clonogenic assay defines tS10 which is 10% survival of the colonies after treatment with the compounds for time “t”. We found that for arctiin, 2hS10 was \u3e100μg/ml, 24hS10 was \u3e100μg/ml and 7dS10 was 1.5μg/ml whereas for AR, 2hS10 was \u3e100μg/ml, 24hS10 was \u3e100μg/ml and 7dS10 was 0.3μg/ml. Maximum Tolerance Dose (MTD) was done in mice for these compounds. Arctiin and AR were administered to the mice both via oral and intravenous (iv) route. For arctiin, MTD was \u3e313 mg/kg for both oral and iv routes and for AR, MTD was above 50mg/kg (oral) and 6.25mg/kg (iv) route. Pharmacokinetic studies are being done to understand the kinetics and the metabolism of these drugs. Based on the studies mentioned above, our data suggests that AR is more potent than arctiin. Additionally, arctiin can likely be used as a prodrug since it is less toxic than arctigenin and is converted to AR. In conclusion, Arctiin and AR have a potential to be developed as drugs for the treatment of solid tumors in humans