A phenolic ester from Aglaia loheri leaves reveals cytotoxicity towards sensitive and multidrug-resistant cancer cells.

BACKGROUND: Bioactivity-guided fractionation of extracts of Aglaia loheri Blanco (Meliaceae) yielded a cytotoxic isolate, termed Maldi 531.2[M + H]+. This phenolic ester was further investigated for its in vitro cytotoxicity toward human CCRF-CEM leukemia cells and their multi-drug resistant (MDR) subline, CEM/ADR5000. The intrinsic mitochondrial membrane potential (ΔΨm) and induction of apoptosis by this isolate were evaluated. METHODS: Chromatography techniques, mass spectrometry and proton NMR were employed to isolate Maldi 531.2[M + H]+. XTT cell proliferation and viability assay was used for cytotoxic test, and JC-1[5',5',6,6',-tetrachloro-1,1',3,3'-tetraethylbenzimidazoyl carbocyanine iodide was used to assess ΔΨm and initiation of apoptosis; Annexin V/FITC-PI staining was employed to analyse apoptosis. RESULTS: Maldi 531.2[M + H]+ was cytotoxic towards both CCRF-CEM and CEM/ADR5000 cells with IC50 values of 0.02 and 0.03 µM, respectively. The mitochondrial membrane potential (ΔΨm) of MDR cells was significantly reduced in a dose-dependent manner leading to apoptosis as detected by flow cytometric Annexin V-FITC/ PI staining. CONCLUSION: Maldi 531.2[M + H]+ may be a potential anti-cancer drug candidate whose mode of action include reduction of the mitochondrial membrane potential and induction of apoptosis.

Polyhydroxylated steroidal glycosides from Paris polyphylla.

Three new steroidal saponins, parisyunnanosides G-I (1-3), one new C(21) steroidal glycoside, parisyunnanoside J (4), and three known compounds, padelaoside B (5), pinnatasterone (6), and 20-hydroxyecdyson (7), were isolated from the rhizomes of Paris polyphylla Smith var. yunnanensis. Compounds 1 and 3 have unique trisdesmoside structures that include a C-21 ß-d-galactopyranose moiety. All compounds were evaluated for their cytotoxicity against human CCRF leukemia cells.

Substrate Specificity of Aglaia loheri Active Isolate towards P-glycoprotein in Multidrug-Resistant Cancer Cells.

Multidrug resistance (MDR) is a major contributory factor in the failure of chemotherapy. Concrete interpretation of P-glycoprotein (P-gp) substrate specificity, whether a substance is a substrate or an inhibitor, represents an important feature of a compound's pharmaceutical profiling in drug design and development. In this work, the P-gp substrate specificity of Maldi 531.2[M+H](+), a phenol ester from Aglaia loheri Blanco leaves was investigated. This study focuses on the effect of Maldi 531.2[M+H](+) on P-gp ATPase activity, which was examined by measuring the amount of inorganic phosphates (Pi) released as a result of ATP hydrolysis. To test the effects of Maldi 531.2[M+H](+) on MDR activity, an attempt to combine Maldi 531.2[M+H](+) with a potent P-gp substrate such as verapamil was performed. As a result of this combination treatment, two distinct patterns of interaction with P-gp activity were determined by a calcein-acetoxymethyl ester (AM) assay. Depending on the concentratgion, both stimulation and inhibition of MDR activity were observed at certain drug concentrations suggesting biphasic reactions, which can be understood as cooperative stimulation and competitive inhibition, respectively. Verapamil is a strong substrate to P-gp. Substrate specificity of Maldi 531.2[M+H](+) may be less than the substrate specificity of verapamil, but it acts additively together with low concentrations of verapamil in stimulating ATPase activity. On the one hand, verapamil and Maldi 531.2[M+H](+) exerted cooperative stimulation on P-gp. On the other hand, Maldi 531.2[M+H](+) acts as competitive inhibitor at higher concentrations.

Biopiracy of natural products and good bioprospecting practice.

BACKGROUND: Biopiracy mainly focuses on the use of biological resources and/or knowledge of indigenous tribes or communities without allowing them to share the revenues generated out of economic exploitation or other non-monetary incentives associated with the resource/knowledge. METHODS: Based on collaborations of scientists from five continents, we have created a communication platform to discuss not only scientific topics, but also more general issues with social relevance. This platform was termed 'PhytCancer -Phytotherapy to Fight Cancer' (www.phyt-cancer.uni-mainz.de). As a starting point, we have chosen the topic "biopiracy", since we feel this is of pragmatic significance for scientists working with medicinal plants. RESULTS: It was argued that the patenting of herbs or natural products by pharmaceutical corporations disregarded the ownership of the knowledge possessed by the indigenous communities on how these substances worked. Despite numerous court decisions in U.S.A. and Europe, several international treaties, (e.g. from United Nations, World Health Organization, World Trade Organization, the African Unity and others), sharing of a rational set of benefits amongst producers (mainly pharmaceutical companies) and indigenous communities is yet a distant reality. In this paper, we present an overview of the legal frameworks, discuss some exemplary cases of biopiracy and bioprospecting as excellent forms of utilization of natural resources. CONCLUSIONS: We suggest certain perspectives, by which we as scientists, may contribute towards prevention of biopiracy and also to foster the fair utilization of natural resources. We discuss ways, in which the interests of indigenous people especially from developing countries can be secured.

In vitro and in vivo evaluations of the performance of an indirubin derivative, formulated in four different self-emulsifying drug delivery systems.

OBJECTIVES: Anticancer indirubins are poorly soluble in water. Here, digestion of four self-emulsifying drug delivery systems (SEDDS) containing E804 (indirubin-3'-oxime 2,3-dihydroxypropyl ether) was compared by dynamic lipolysis and bioavailability studies. Used lipids were either medium-chain or long-chain glycerides. METHODS: SEDDS E804 were developed. In-vitro lipolysis was carried out at pH 6.5 (37°C) by adding pancreatic lipase (800 U/ml) and controlling by CaCl2 and NaOH addition. E804 content was quantified in the aqueous micellar phase and precipitate using HPLC. Oral bioavailability was determined in rats. Plasma drug content was determined by liquid chromatography (LC)-mass spectrometry. KEY FINDINGS: All formulations reserved E804 in the aqueous micellar phase up to 60 min. Precipitation proceeded towards the end of lipolysis up to 45%. Lowest level of precipitation (21%) occurred with long-chain lipids (LC-SEDDS). However, lipolysis was not really discriminative between formulations as the drug mainly stayed in solution. Oral administration of formulations resulted in similar bioavailability of E804 with no significantly different area under the concentration curve. Only medium-chain self-nanoemulsifying drug delivery systems revealed shorter Tmax compared with the other formulations. CONCLUSION: E804 had a similar performance in four lipid/surfactant systems. All formulations increased the bioavailability of E804 with no significant difference.