Intercalating agents with covalent bond forming capability. A novel type of potential anticancer agents. 2. Derivatives of chrysophanol and emodin

Comparative analysis of an anthraquinone and chalcone derivatives-based virtual combinatorial library. A cheminformatics "proof-of-concept" study

A Laplacian scoring algorithm for gene selection and the Gini coefficient to identify the genes whose expression varied least across a large set of samples were the state-of-the-art methods used here. These methods have not been trialed for their feasibility in cheminformatics. This was a maiden attempt to investigate a complete comparative analysis of an anthraquinone and chalcone derivatives-based virtual combinatorial library. This computational "proof-of-concept" study illustrated the combinatorial approach used to explain how the structure of the selected natural products (NPs) undergoes molecular diversity analysis. A virtual combinatorial library (1.6 M) based on 20 anthraquinones and 24 chalcones was enumerated. The resulting compounds were optimized to the near drug-likeness properties, and the physicochemical descriptors were calculated for all datasets including FDA, Non-FDA, and NPs from ZINC 15. UMAP and PCA were applied to compare and represent the chemical space coverage of each dataset. Subsequently, the Laplacian score and Gini coefficient were applied to delineate feature selection and selectivity among properties, respectively. Finally, we demonstrated the diversity between the datasets by employing Murcko's and the central scaffolds systems, calculating three fingerprint descriptors and analyzing their diversity by PCA and SOM. The optimized enumeration resulted in 1,610,268 compounds with NP-Likeness, and synthetic feasibility mean scores close to FDA, Non-FDA, and NPs datasets. The overlap between the chemical space of the 1.6 M database was more prominent than with the NPs dataset. A Laplacian score prioritized NP-likeness and hydrogen bond acceptor properties (1.0 and 0.923), respectively, while the Gini coefficient showed that all properties have selective effects on datasets (0.81-0.93). Scaffold and fingerprint diversity indicated that the descending order for the tested datasets was FDA, Non-FDA, NPs and 1.6 M. Virtual combinatorial libraries based on NPs can be considered as a source of the combinatorial compound with NP-likeness properties. Furthermore, measuring molecular diversity is supposed to be performed by different methods to allow for comparison and better judgment.

A Review of Anti-Cancer and Related Properties of Lichen-Extracts and Metabolites

BACKGROUND

Lichens are a composite consortium of fungus and alga. The symbiotic organisms are naturally equipped with distinct characteristics as compared to constituting organisms separately. Lichens due to their peculiar anatomy and physiology, are the reservoir of more than 600 unique secondary metabolites, also known as 'lichen substances'. Since ancient times, many ethnic groups from various parts of the world had knowledge about the applications of lichens as major provenance of food/fodder, medicine, dyes, spices, perfumes, etc. Lichen substances have shown impressive antioxidant, antimicrobial, antiviral, antitumor, and anti-inflammatory activities under experimental conditions. Usnic acid, a well-known metabolite, found in several species of lichens, possesses potent antioxidant and anti-inflammatory activities. It also has significant anti-proliferative potential as revealed through testing in different cancer cell lines. Atranorin, Lecanoric acid, Norstictic acid, Lobaric acid, Stictic acid, Ramalin, Gyrophoric acid, Salazinic acid, Protolichesterinic, and Fumarprotocetraric acid are some of the other purified lichen metabolites with potent anti-cancer activities.

OBJECTIVE

This study presents an overview of lichen derived extracts/compounds augmenting the anti-cancer (related) properties.

METHOD

The review comprehends different studies (in vivo and in vitro) backing up the possibility of lichen extracts and metabolites towards their use as antioxidant, anti-proliferative, anti-inflammatory and EMT-inhibiting agents.

RESULTS

The review focuses on anti-cancer and related properties of lichen extracts and metabolites that include their anti-oxidative, anti-inflammatory, anti-proliferative and pro-apoptotic, cancer stemness reduction, activities and, the potential of inhibition of cancer-associated Epithelial-mesenchymal transition (EMT) that is responsible for multiple drug-resistance and metastasis of cancer cells in a large proportion of cases.

CONCLUSION

Lichens can be the repertoire of a plethora of lichen metabolites with putative bioactive potential, which is needed to be explored in order to find out novel anti-cancer drugs.

In the Mists of a Fungal Metabolite: An Unexpected Reaction of 2,4,5-Trimethoxyphenylglyoxylic Acid

The reactions of phenylglyoxylic acids during the synthesis and biological evaluation of fungal metabolites led to the discovery of hitherto unknown compounds with a p-quinone methide (p-QM) structure. The formation of these p-QMs using ¹³C-labelled starting materials revealed a key-step of this reaction being a retro-Friedel–Crafts alkylation.

NBO-Analysis of Peri-dihydroxy-9,10-anthraquinones and their Deprotonated Forms

The natural bonding orbitals (NBO) approach is employed to gain a deeper insight into the nature of intramolecular interactions in a series of peri-hydroxyderivatives of 9,10-anthraquinones and their deprotonated forms. The intuitive predictions of relative energies of these species and the strength of hydrogen bonding were confirmed by the NBO analysis, whereas intuitive evaluation of the role of steric effects in the stability of deprotonated hydroxyanthraquinones seemed to be exaggerated.

Design and synthesis of emodin derivatives as novel inhibitors of ATP-citrate lyase

Aberrant cellular metabolism drives cancer proliferation and metastasis. ATP citrate lyase (ACL) plays a critical role in generating cytosolic acetyl CoA, a key building block for de novo fatty acid and cholesterol biosynthesis. ACL is overexpressed in cancer cells, and siRNA knockdown of ACL limits cancer cell proliferation and reduces cancer stemness. We characterized a new class of ACL inhibitors bearing the key structural feature of the natural product emodin. Structure-activity relationship (SAR) study led to the identification of 1d as a potent lead that demonstrated dose-dependent inhibition of proliferation and cancer stemness of the A549 lung cancer cell line. Computational modeling indicates this class of inhibitors occupies an allosteric binding site and blocks the entrance of the substrate citrate to its binding site.

Design and synthesis of novel hydroxyanthraquinone nitrogen mustard derivatives as potential anticancer agents via a bioisostere approach

A series of hydroxyanthraquinones having an alkylating N-mustard pharmacophore at 1'-position were synthesized via a bioisostere approach to evaluate their cytotoxicity against four tumor cell lines (MDA-MB-231, HeLa, MCF-7 and A549). These compounds displayed significant in vitro cytotoxicity against MDA-MB-231 and MCF-7 cells, reflecting the excellent selectivity for the human breast cancer. Among them, compound 5k was the most cytotoxic with IC50 value of 0.263 nM and is more potent than DXR (IC50 = 0.294 nM) in inhibiting the growth of MCF-7 cells. The excellent cytotoxicity and good selectivity of compound 5k suggest that it could be a promising lead for further design and development of anticancer agents, especially for breast cancer.

Synthesis and biological activity evaluation of emodin quaternary ammonium salt derivatives as potential anticancer agents

Twenty-six emodin derivatives (17 novel) which attach quaternary ammonium salt were synthesized and evaluated for their anticancer activities in vitro and in vivo. Compounds 11g + 12g and 11h + 12h had more significant antiproliferative ability against three cancer cell lines and low cytotoxicity to HELF. 11g + 12g and 11h + 12h induced AGS cell apoptosis and arrested cell cycle at the G(0)/G(1) phase in a dose-dependent manner. Furthermore, the activities of the caspase-3, -9 enzymes were increased in the treated cells. In vivo studies revealed that compounds 11g + 12g and 11h + 12h showed significant anti-tumor activity compared with controlled group.

Synthesis and antitumor activity of emodin quaternary ammonium salt derivatives

A series of new emodin derivatives modified at the C-3 and the C-6 positions were synthesized, and evaluated for their anticancer activities in vitro and in vivo. Among them, Compounds 5g and 5h had more significant antiproliferative ability against HepG2, BGC-823, AGS cancer cell lines and low cytotoxicity to HELF normal cell line, respectively. Compounds 5g and 5h induced AGS cell cycle arrest at G0/G1 phase and induce apoptosis via activation of caspase-3 and caspase-9 enzyme. In vivo studies using H22 xenografts in Kunming mice were conducted with 5g and 5h. The results revealed that the medium dosage group (10 mg/kg) of 5g and the high dosage group (25 mg/kg) of 5h showed significant antitumor activity compared to the control group.

Synthesis and antitumor activity of conjugates of 5-Fluorouracil and emodin

A series of conjugates of 5-Fluorouracil (5-FU) and emodin were synthesized by coupling trimethyl emodin with N(1), N(3) dialkylated 5-FU. The 5-FU moiety contained various substituents at the N(3)-position were linked to the 2-position of trimethyl emodin via a methylene linkage. Their cytotoxicity against three cancer cell lines and one noncancerous cell were studied. The results revealed that some of conjugates exhibited better or comparable in vitro antitumor activity to 5-FU and emodin and low toxicity in the normal cell. The structure-activity relationship study showed N(3)-aromatic substituent was important for their cytotoxic activity.

Novel rhein analogues as potential anticancer agents

Two series of rhein analogues were synthesized with modification at the 3-position. Their cytotoxicities were evaluated using an MTT assay. Among all the compounds synthesized, one compound showed the best potency, with an IC(50) value of 2.7 μM against the HeLa cell line and 0.6 μM against the MOLT4 cell line.

Structural and spectral assignments of six anthraquinone derivatives from the mangrove fungus (ZSUH-36)

A new natural product named 6,8,1'-tri-O-methyl averantin (1) has been isolated together with five known anthraquinones 1'-O-methyl averantin (2), 6,8-di-O-methyl averufin (3) averufin (4), versicolorin C (5) and 6,8-di-O-methyl averufanin (6) from a mangrove endophytic fungus ZSUH-36 collected from the South China Sea. NMR techniques including COSY, HMQC, and HMBC were used to elucidate the structures of these compounds. We report the unambiguous assignments of the (1)H and (13)C NMR spectra of the new compound 6,8,1'-tri-O-methyl averantin(1).

Preparation of 1,8-di-O-alkylaloe-emodins and 15-amino-, 15-thiocyano-, and 15-selenocyanochrysophanol derivatives from aloe-emodin and studying their cytotoxic effects

1,8-di-O-alkylaloe-emodin derivatives (namely, methyl-, propyl-, hexyl-, dodecyl-, and octadecyl) were synthesized from naturally occurring aloe-emodin. Further, derivatives having various substituents such as diethylamino, pyrrolidinyl, piperidinyl, methylpiperazinyl, imidazolyl, thiocyano and selenocyano groups at the 15 position of chrysophanol and 1,8-di-O-hexylchrysophanol from aloe-emodin were synthesized. The cytotoxic effects of these derivatives on less P-glycoprotein (P-gp)-expressing HCT 116 cells and stably P-gp-expressing Hep G2 cells were evaluated by performing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Among these products, several of them exhibited markedly higher potent cytotoxic effects not only on HCT116 cells but also Hep G2 cancer cells as compared to aloe-emodin.

Metal ion induced allosteric transition in the catalytic activity of an artificial phosphodiesterase

An artificial phosphodiesterase () bearing two types of metal binding sites, a catalytic site and a regulatory bipyridine site showed a unique allosteric transition in the catalytic activity against the metal concentration. The rate constants for the hydrolysis reaction of 2-hydroxypropyl-p-nitrophenyl phosphate (HPNP) and RNA dimer (ApA) with and without an effector metal ion were evaluated; the k(obs) value of HPNP hydrolysis for .(Zn(2+))(3) (2.0 x 10(-4) s(-1)) is 3.3 times larger than that for .(Zn(2+))(2). In the case of and Cu(2+), a 19.4 times larger k(obs) value was obtained for .(Cu(2+))(3) (1.2 x 10(-3) s(-1)) against .(Cu(2+))(2). The increase in the catalytic activity is ascribed to the allosteric conformational transition of induced by the coordination of effector metal ion to the Bpy moiety. A detailed investigation revealed that a conformational change of induced by the third M(2+) complexation enhances the rate of hydrolysis rather than a change in the substrate affinity.

Synthesis, DNA binding, and cytotoxicity studies of pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone conjugates

A series of pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone conjugates have been prepared and evaluated for their DNA binding ability as well as anticancer activity. Some of these molecules have shown significant anticancer activity in a number of cancer cell lines.

Comparison of the cytotoxic activities of naturally occurring hydroxyanthraquinones and hydroxynaphthoquinones

Seven hydroxyanthraquinone derivatives, 1-7, were isolated from the root of Rheum palmatum (Polygonaceae). Two propionated anthraquinone derivatives, 8 and 9, were synthesized. Four hydroxynaphthoquinone derivatives, 13, 14, 16 and 21, were isolated from the root of Lithospermum erythrorhizon Sieb. et Zucc. (Boraginaceae) and also three naphthoquinone derivatives, 19, 22 and 23, were isolated from the root of Macrotomia euchroma (Royle) Pauls. (Boraginaceae). The cytotoxicity of the anthraquinone and naphthoquinone derivatives on P-gp-underexpressing HCT 116 cells and P-gp-overexpressing Hep G2 cells was examined by MTT assay. Among the anthraquinone derivatives, compounds 3-5 which had OH, CH(2)OH and COOH substituent groups on the anthraquinone skeletons, respectively, showed potent growth inhibitory activities against both types of cancer cells (IC(50) values: 5.7+/-0.9 to 13.0+/-0.7 microM in the case of HCT 116 cells and 5.2+/-0.7 to 12.3+/-0.9 microM in the case of Hep G2 cells). All hydroxynaphthoquinone derivatives isolated in this study exhibited extremely potent growth inhibitory activities against both types of cancer cells (IC(50) values: 0.3+/-0.09 to 0.46+/-1.0 microM in the case of HCT 116 cells and 0.22+/-0.03 to 0.59+/-0.06 microM in the case of Hep G2 cells) as well as shikonin 10 (IC(50) values: 0.32+/-0.02 microM in the case of HCT 116 cells and 0.24+/-0.03 microM in the case of Hep G2 cells).

Theoretical basis, experimental design, and computerized simulation of synergism and antagonism in drug combination studies

The median-effect equation derived from the mass-action law principle at equilibrium-steady state via mathematical induction and deduction for different reaction sequences and mechanisms and different types of inhibition has been shown to be the unified theory for the Michaelis-Menten equation, Hill equation, Henderson-Hasselbalch equation, and Scatchard equation. It is shown that dose and effect are interchangeable via defined parameters. This general equation for the single drug effect has been extended to the multiple drug effect equation for n drugs. These equations provide the theoretical basis for the combination index (CI)-isobologram equation that allows quantitative determination of drug interactions, where CI < 1, = 1, and > 1 indicate synergism, additive effect, and antagonism, respectively. Based on these algorithms, computer software has been developed to allow automated simulation of synergism and antagonism at all dose or effect levels. It displays the dose-effect curve, median-effect plot, combination index plot, isobologram, dose-reduction index plot, and polygonogram for in vitro or in vivo studies. This theoretical development, experimental design, and computerized data analysis have facilitated dose-effect analysis for single drug evaluation or carcinogen and radiation risk assessment, as well as for drug or other entity combinations in a vast field of disciplines of biomedical sciences. In this review, selected examples of applications are given, and step-by-step examples of experimental designs and real data analysis are also illustrated. The merging of the mass-action law principle with mathematical induction-deduction has been proven to be a unique and effective scientific method for general theory development. The median-effect principle and its mass-action law based computer software are gaining increased applications in biomedical sciences, from how to effectively evaluate a single compound or entity to how to beneficially use multiple drugs or modalities in combination therapies.

Potent Antitumor 9-Anilinoacridines and Acridines Bearing an AlkylatingN-Mustard Residue on the Acridine Chromophore: Synthesis and Biological Activity

A series of 9-anilinoacridine and acridine derivatives bearing an alkylating N-mustard residue at C4 of the acridine chromophore were synthesized. The N-mustard pharmacophore was linked to the C4 of the acridine ring with an O-ethyl (O-C(2)), O-propyl (O-C(3)), or O-butyl (O-C(4)) spacer. It revealed that all newly synthesized compounds were very potent cytotoxic agents against human leukemia and various solid tumors in vitro. These agents did not exhibit cross-resistance against vinblastine-resistant (CCRF-CEM/VBL) or taxol-resistant (CCRF-CEM/taxol) cells. It also showed that these agents were DNA cross-linking agents rather than topoisomerase II inhibitors. Of these agents, compounds 27a and 27c were shown to have potent antitumor activity in nude mice bearing the human breast carcinoma MX-1 xenograft. The therapeutic efficacies of these two agents are comparable to that of taxol.

Potent antitumor 9-anilinoacridines bearing an alkylating N-mustard residue on the anilino ring: synthesis and biological activity

A series of N-mustard derivatives of 9-anilinoacridine was synthesized for antitumor and structure-activity relationship studies. The alkylating N-mustard residue was linked to the C-3' or C-4' position of the anilino ring with an O-ethylene (O-C(2)), O-butylene (O-C(4)), and methylene (C(1)) spacer. All of the new N-mustard derivatives exhibited significant cytotoxicity in inhibiting human lymphoblastic leukemic cells (CCRF-CEM) in culture. Of these agents, (3-(acridin-9-ylamino)-5-{2-[bis (2-chloroethyl)amino]ethoxy}phenyl)methanol (10) was subjected to antitumor studies, resulting in an approximately 100-fold more potent effect than its parent analogue 3-(9-acridinylamino)-5-hydroxymethylaniline (AHMA) in inhibiting the growth of human lymphoblastic leukemic cells (CCRF-CEM) in vitro. This agent did not exhibit cross-resistance against vinblastine-resistant (CCRF-CEM/VBL) or Taxol-resistant (CCRF-CEM/Taxol) cells. Remarkably, the therapeutic effect of 10 at a dose as low as one tenth of the Taxol therapeutic dose [i.e., 1-2mg/kg (Q3Dx7) or 3mg/kg (Q4Dx5); intravenous injection] on nude mice bearing human breast carcinoma MX-1 xenografts resulted in complete tumor remission in two out of three mice. Furthermore, 10 yielded xenograft tumor suppression of 81-96% using human T-cell acute lymphoblastic leukemia CCRF-CEM, colon carcinoma HCT-116, and ovarian adenocarcinoma SK-OV-3 tumor models.

Pyrrolo[2,1-c][1,4]benzodiazepine–anthraquinone conjugates. Synthesis, DNA binding and cytotoxicity

New pyrrolobenzodiazepine-anthraquinone hybrids have been designed and synthesized, found to effectively bind to DNA and also exhibit cytotoxicity against many cancer cell lines

Potent antitumor N-mustard derivatives of 9-anilinoacridine, synthesis and antitumor evaluation

A series of 9-anilinoacridine N-mustard derivatives, in which the alkylating N-mustard residue was linked to the C-3' or C-4' position of the anilino ring with an O-ethylene spacer, was synthesized and evaluated for cytotoxicity against human lymphoblastic leukemic cells (CCRF-CEM) in culture. The results showed that all of the new compounds exhibited potent cytotoxicity with IC(50) values ranging from 0.002 to 0.7 microM, which were as potent or significantly more potent than 3-(9-acridinylamino)-5-hydroxymethylaniline (AHMA). Compound 9 did not exhibit cross-resistance against both vinblastine-resistant (CCRF-CEM/VBL) and taxol-resistant (CCRF-CEM/taxol) cells. Additionally, compound 9 demonstrated potent antitumor effect in nude mice bearing human breast carcinoma MX-1 xenografts, resulting in complete tumor remission in two out of three mice at the maximal dose of 1-2mg/kg (Q3Dx7) or 3mg/kg (Q4Dx5) via intravenous injection.

Generation of free radicals by emodic acid and its [D-Lys6]GnRH-conjugate

In an attempt to develop an efficient chemotherapeutic agent targeted at malignant cells that express receptors to gonadotropin releasing hormone (GnRH) we coupled [D-Lys6]GnRH covalently to an emodin derivative, i.e. emodic acid (Emo) to yield [D-Lys6(Emo)]GnRH. Emodin is a naturally occurring anthraquinone which is widely used as a laxative and has other versatile biological activities. Physico-chemical studies employing electron paramagnetic resonance and electrochemistry of the conjugate as well as the (Emo) moiety showed that these compounds could be easily reduced either chemically, photochemically or enzymatically to their corresponding semiquinones. In the presence of oxygen the semiquinones generated reactive oxygen species (ROS), mainly superoxide and hydroxyl radicals, which were detected by the spin trapping method. Moreover, upon irradiation with visible light these compounds produced ROS and a highly reactive excited triplet state of Emo, which by itself may cause the oxidation of certain electron acceptors such as amino acids and bases of nucleic acids. Thus, [D-Lys6]GnRH-photosensitizer conjugates may be potentially used for targeted photodynamic chemotherapy aimed at treating cancer cells that carry GnRH receptors. These conjugates may also induce cytotoxicity in the dark similar to common conventional chemotherapeutic agents. The peptidic moiety, [D-Lys6]GnRH, was found to be stable toward highly reactive ROS generated either from enzymatic reduction or upon photoirradiation. The physico-chemical properties of Emo were only marginally influenced by the peptidic [D-Lys6]GnRH carrier.

Esters of chlorambucil with 2-substituted 1,4-dihydroxy-9,10-anthraquinones as multifunctional anticancer agents

Novel twelve esters of chlorambucil with 2-(1-hydroxyalkyl)-1,4-dihydroxy-9,10-anthraquinone were synthesized and tested for their antitumor activity in mice bearing S-180 ascitic cells as well as cytotoxic activity against L1210 cells. Eight of them were highly cytotoxic on L1210 cells (ED(50), <6 microg mL(-1)) and derivatives 1 and 12 (T/C, 200 and 205%) appeared more active in vivo than chlorambucil (T/C, 168%).

Synthesis and evaluation of the antitumor activity of 2-substituted 1,4-dihydroxy-9,10-anthraquinones

2-(1-Hydroxyiminoalkyl)-1,4-dimethoxy-9,10-anthraquinones were demethylated to produce 2-(1-hydroxyiminoalkyl)-1,4-dihydroxy-9,10-anthraquinones (1,4-dihydroxy-9,10-anthraquinone, DHAQ), oxime hydroxyl groups were in turn acylated to give the corresponding 2-(1-acyloxyiminoalkyl)-DHAQ derivatives. The anti-proliferative activity of 2-(1-hydroxyiminoalkyl)-DHAQ derivatives was found to be dependent on the size of an alkyl chain. Thus, DHAQ analogues with alkyl chains longer than heptyl had negligible anti-proliferative activity, whilst those compounds possessing shorter chains demonstrated moderate anti-proliferative activity (ED50, 2.73-19.21 microM). However, the antitumor activity as expressed by T/C values did not correlate with the anti-proliferative activity; 2-(1-hydroxyiminononyl)-DHAQ with an ED50 value of more than 20 microM exhibited potent antitumor activity (T/C, 166%). Only four of the 2-(1-hydroxyiminoalkyl)-DHAQ analogues showed good antitumor activity (T/C, > 150%); 2-(1-hydroxyiminobutyl)-DHAQ (T/C, 163%), 2-(1-hydroxyiminopentyl)-DHAQ (T/C, 180%) and 2-(1-hydroxyiminononyl)-DHAQ (T/C, 166%). Acylation of the hydroxyl group of these oximes enhanced the anti-proliferative activity and antitumor effects; 2-(1-propanoyloxyiminopropyl)-DHAQ (ED50, 4.41 microM; T/C, 221%) vs. 2-(1-hydroxyiminopropyl)-DHAQ (ED50, 14.64 microM; T/C, 100%) and 2-(1-propanoyloxyiminobutyl)-DHAQ (ED50, 2.65 microM; T/C, 202%) vs. 2-(1-hydroxyiminobutyl)-DHAQ (ED50, 16.43 microM; T/C, 163%).

Anti-leukaemic and anti-mutagenic effects of di(2-ethylhexyl)phthalate isolated from Aloe vera Linne

Extracts of Aloe vera Linne have been found to exhibit cytotoxicity against human tumour cell lines. This study examines the anti-tumour effects of di(2-ethylhexyl)phthalate (DEHP) isolated from Aloe vera Linne, in human and animal cell lines. Its anti-mutagenic effects were examined using Salmonella typhimurium TA98 and TA100 strains. Growth inhibition was specifically exerted by DEHP against three leukaemic cell lines at concentrations below 100 microg mL(-1). At 100 microg mL(-1) DEHP, K562, HL60 and U937 leukaemic cell lines showed growth inhibition of 95, 97 and 95%, respectively. DEHP exhibited an inhibitory activity of 74, 83 and 81%, respectively, in K562, HL60 and U937 cell lines at a concentration of 10 microg mL(-1). At a concentration of 1 microg mL(-1), DEHP exerted an inhibitory activity of 50, 51 and 52%, respectively, in K562, HL60 and U937. In a normal cell line, MDBK, DEHP exerted 30% growth inhibition at a concentration of 100 microg mL(-1), and showed no inhibitory activity at concentrations below 50 microg mL(-1). It was found that DEHP exerted anti-mutagenic activity in the Salmonella mutation assay. The number of mutant colonies of Salmonella typhimurium strain TA98 upon exposure to AF-2 (0.2 microg/plate) decreased in a concentration-dependent manner in the presence of different DEHP concentrations (decreasing to 90.4, 83.9, 75.4, 69.6 and 46.9%, respectively, for DEHP concentrations of 100, 50, 10, 5 and 1 microg/plate). In the case of Salmonella typhimurium strain TA100, DEHP reduced AF-2-induced mutagenicity at 1, 5, 10, 50 and 100 microg/plate to 57.4, 77.5, 80.0, 89.0 and 91.5%, respectively. The isolated compound from Aloe vera Linne, DEHP, was considered to be the active principle responsible for anti-leukaemic and anti-mutagenic effects in-vitro.

2-(1-Oxyalkyl)-1,4-dioxy-9,10-anthraquinones: synthesis and evaluation of antitumor activity

Fourty eight derivatives of 2-(1-oxyalkyl)-1,4-dioxy-9,10-anthraquinone were synthesized, and their antitumor activity was evaluated. On the whole, 2-(1-hydroxyalkyl)-1,4-dihydroxy-9,10-anthraquinones (DHAQ = 1,4-dihydroxy-9,10-anthraquinone) showed stronger cytotoxic activity against L1210 cells than 2-(1-hydroxyalkyl)-1,4-dimethoxy-9,10-anthraquinones(DMAQ = 1,4-dimethoxy-9,10-anthraquinone), implying that free hydroxy groups at C-1 and C-4 of the anthraquinone structure are necessary for the cytotoxic activity. The bioactivity of 2-(1-hydroxyalkyl)-DHAQ derivatives differed according to the size of alkyl group at C-1; while the elongation of alkyl group over 7 carbon atoms failed to enhance the bioactivity, the derivatives possessing alkyl moiety of 1-6 carbon atoms showed an increase in the cytotoxicity and the antitumor activity in Sarcoma-180; 2-hydroxymethyl-DHAQ (ED50, 15 micrograms/ml; T/C, 125%), 2-(1-hydroxyethyl)-DHAQ(1.9 micrograms/ml; 139.2%), 2-(1-hydroxypropyl)-DHAQ (7.2 micrograms/ml; 135.1%), 2-(1-hydroxybutyl)-DHAQ (10.2 micrograms/ml; 125.3%), 2-(1-hydroxypentyl)-DHAQ (23.7 micrograms/ml; 110.1%), and 2-(1-hydroxyhexyl)-DHAQ (58 micrograms/ml; 108%). Next, 2-(1-Hydroxyalkyl)-DHAQ derivatives were acetylated to produce 2-(1-acetoxyalkyl)-DHAQ analogues. Although the acetylation somewhat enhanced the cytotoxicity, but not the antitumor action. In addition, the presence of phenyl group at C-1' enhanced the cytotoxicity and the T/C value, compared to alkyl groups of same size; 2-(1-hydroxy-1-phenyl)-DHAQ (ED50, 5.6 micrograms/ml; T/C, 137%).

Synthesis of antineoplaston A10 analogs as potential antitumor agents

Several aniline mustard analogues were obtained by introducing N,N-bis(2-chloroethyl)amino moiety to phenyl ring of A10 analogues in order to increase reactivity of A10 analogs and selectivity into DNA. The in vitro antitumor activity of synthesized compounds was evaluated using five different solid tumor cell lines by SRB method. Aniline mustard analogues exhibited more potent antitumor activity than A10 analogs. Especially, m-aniline mustard of benzoyl analogue displayed remarkable antitumor activity.

Inhibitory actions of emodin on arylamine N-acetyltransferase activity in strains of Helicobacter pylori from peptic ulcer patients

Arylamine N-acetyltransferase (NAT) activities with p-aminobenzoic acid and 2-aminofluorene were determined in Helicobacter pylori, a gram-negative rod bacteria collected from peptic ulcer patients. The NAT activity was determined using a acetyl CoA recycling assay and HPLC. Cytosols or suspensions of H. pylori with and without selected concentrations of emodin co-treatment showed different percentages of 2-aminofluorene and p-aminobenzoic acid acetylation. The data indicate that there were decreased NAT activity associated with increased emodin in H. pylori cytosols. As 400 microns of emodin can obviously inhibit NAT activity both in vitro and in vivo (inhibition rate 90% and 93% for 2-aminofluorene and p-aminobenzoic acid in vitro, and 90% and 92%, respectively, for both substrate in vivo). For in vitro examination, the apparent values of Km and Vmax were 3.12 +/- 0.38 mM and 15.20 +/- 3.16 nmol/min/mg protein for 2-aminofluorene, and 0.56 +/- 0.12 mM and 0.74 +/- 0.09 nmol/min mg protein for p-aminobenzoic acid. However, when emodin was added to the reaction mixtures, the values of apparent Km and Vmax were 2.40 +/- 0.32 mM and 10.62 +/- 0.04 nmol/min/mg protein for 2-aminofluorene, and 0.23 +/- 0.02 mM and 0.62 +/- 0.08 nmol/min/mg protein for p-aminobenzoic acid. For in vivo examination, the apparent Km and Vmax were 0.82 +/- 0.18 mM and 0.92 +/- 0.21 nmol/min/10 x 10(10) colony forming units (CFU) for 2-aminofluorene, and 0.78 +/- 0.14 mM and 0.52 +/- 0.06 nmol/min/ 10 x 10(10) (CFU) for p-aminobenzoic acid. However, when emodin was added to the reaction mixtures, the values of apparent Km and Vmax were 0.50 +/- 0.08 mM and 0.62 +/- 0.22 nmol/min/ 10 x 10(10) (CFU) for 2-aminofluorene, and 0.52 +/- 0.21 mM and 0.26 +/- 0.04 nmol/min/ 10 x 10(10) (CFU) for p-aminobenzoic acid. This report is the first finding of emodin inhibition of arylamine N-acetyltransferase activity in a strain of H. pylori.

Antitumor agents--CLXVII. Synthesis and structure-activity correlations of the cytotoxic anthraquinone 1,4-bis-(2,3-epoxypropylamino)-9,10-anthracenedione, and of related compounds

1,4-Bis-(2,3-epoxypropylamino)-9,10-anthracenedione (3) was synthesized in this laboratory and was found to be a potent antitumor agent. Derivatives of this compound containing anthraquinone, naphthoquinone, and quinone skeletons were also prepared and evaluated for in vitro cytotoxic activity in several cell lines. These molecules were designed as bifunctional antitumor agents with the potential to act as (1) intercalating agents due to their planar backbones, and (2) alkylating agents due to the presence of alkylating moieties in their side chains. Compounds with an anthraquinone skeleton and propylamino side chains containing epoxides or halohydrins as the alkylating species showed greater activity than similar compounds with naphthoquinone or quinone skeletons. Compounds without these alkylating functionalities (e.g., with alkene or amino groups) were generally inactive. Hydroxy substitution on the planar skeleton in conjunction with alkylating side chains gave compounds with the most potent cytotoxic activity. The position of the hydroxy groups and side chains could be varied without substantially affecting activity. Activity was retained when an epoxypropyloxy side chain was substituted for the epoxypropylamino side chain in the parent compound.