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Targeted therapy has been recently highlighted due to the reduction of side effects and improvement in overall efficacy and survival from different types of cancers. Considering the approval of many monoclonal antibodies in the last twenty years, cancer treatment can be accomplished by the combination of monoclonal antibodies and small molecule chemotherapeutics. Thus, strategies to combine both drugs in a single administration system are relevant in the clinic. In this context, two strategies are possible and will be further discussed in this review: antibody-drug conjugates (ADCs) and antibody-functionalized nanoparticles. First, it is important to better understand the possible molecular targets for cancer therapy, addressing different antigens that can selectively bind to antibodies. After selecting the best target, ADCs can be prepared by attaching a cytotoxic drug to an antibody able to target a cancer cell antigen. Briefly, an ADC will be formed by a monoclonal antibody (MAb), a cytotoxic molecule (cytotoxin) and a chemical linker. Usually, surface-exposed lysine or the thiol group of cysteine residues are used as anchor sites for linker-drug molecules. Another strategy that should be considered is antibody-functionalized nanoparticles. Basically, liposomes, polymeric and inorganic nanoparticles can be attached to specific antibodies for targeted therapy. Different conjugation strategies can be used, but nanoparticles coupling between maleimide and thiolated antibodies or activation with the addition of ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC)/ N-hydroxysuccinimide (NHS) (1:5) and further addition of the antibody are some of the most used strategies. Herein, molecular targets and conjugation strategies will be presented and discussed to better understand the in vitro and in vivo applications presented. Also, the clinical development of ADCs and antibody-conjugated nanoparticles are addressed in the clinical development section. Finally, due to the innovation related to the targeted therapy, it is convenient to analyze the impact on patenting and technology. Information related to the temporal evolution of the number of patents, distribution of patent holders and also the number of patents related to cancer types are presented and discussed. Thus, our aim is to provide an overview of the recent developments in immunoconjugates for cancer targeting and highlight the most important aspects for clinical relevance and innovation.

Prostate cancer is the second most common malignancy in men and the development of effective therapeutic strategies remains challenging when more advanced, androgen-independent or insensitive forms are involved. Accordingly, we have evaluated, using flow cytometry, confocal microscopy and image analysis, the anti-proliferative effects of (+)-2,3,9-trimethoxypterocarpan [(+)-PTC, 1] on relevant human prostate cancer cells as well as its capacity to control mitosis within them. In particular, the studies reported herein reveal that (+)-PTC exerts anti-proliferative activity against the PC-3 cell lines by regulating cell-cycle progression with mitosis being arrested in the prophase or prometaphase. Furthermore, it emerges that treatment of the target cells with this compound results in the formation of monopolar spindles, disorganized centrosomes and extensively disrupted γ-tubulin distributions while centriole replication remains unaffected. Such effects suggest (+)-PTC should be considered as a possible therapy for androgen-insensitive/independent prostate cancer.

Ortho-Quinones represent a special class of redox active compounds associated with a spectrum of pronounced biological activities, including selective cytotoxicity and antimicrobial actions. The modification of the quinone ring by simple nitrogen and sulphur substitutions leads to several new classes of compounds with their own, distinct redox behaviour and equally distinct activities against cancer cell lines and Trypanosoma cruzi. Some of the compounds investigated show activity against T. cruzi at concentrations of 24.3 and 65.6 μM with a selectivity index of around 1. These results demonstrate that simple chemical modifications on the ortho-quinone ring system, in particular, by heteroatoms such as nitrogen and sulphur, transform these simple redox molecules into powerful cytotoxic agents with considerable “potential”, not only in synthesis and electrochemistry, but also, in a broader sense, in health sciences.

Oncocalyxone A, a 1,4-benzoquinone derived from Cordia oncocalyx, exhibits anti-inflammatory, antimicrobial and antidiabetic properties. The aim of this study was to (1) examine the cytotoxic actio...

The tambjamines are a small group of bipyrrolic alkaloids that, collectively, display a significant range of biological activities including antitumor, antimicrobial and immunosuppressive properties. The key objective of the present study was to undertake preclinical assessments of tambjamine J (T-J) so as to determine its in vivo antitumor effects. To that end, sarcoma 180 cells were transplanted in mice and the impacts of the title compound then evaluated using a range of protocols including hematological, biochemical, histopathological, genotoxic and clastogenic assays. As a result it was established that this alkaloid has a significant therapeutic window and effectively reduces tumor growth (by 40 % and 79 % at doses of 10 and 20 mg/kg/day, respectively). In this regard it displays similar antitumor activity to the anticancer agent cyclophosphamide and alters animal weight in an analogous manner.

In this paper, we complement our previous study on the antiproliferative activity of Calea fruticosa (Asteraceae) by isolating the compounds apigenin-4',7-dimethyl ether (1), budlein A (2), quercetin (3), and cichoriin (4) from the plant’s aerial parts. The antiproliferative activity of these compounds was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method against human tumor cell lines. Compound 3 displayed moderate antiproliferative activity in three cell lines (HCT-116, PC-3, and SF-295, with cell growth inhibition values of 72.97, 74.55, and 68.94%) and high antiproliferative activity (90.86%) in the HL-60 cell line. The in vitro sun protection factor (SPF) of the extracts and compound 4, with and without sunscreen, was determined by a spectrophotometric method. The ethanol extract exhibited the highest SPF (9.67) at a concentration of 0.100 mg/mL, while compound 4, isolated from this extract, showed a SPF of 13.79 at the same concentration. A relative increased efficacy of SPF was observed for the extracts and compound 4 when sunscreen was also used. Compound 4 has not been reported previously from any species within the genus Calea. Compounds 1–4 were obtained from this species for the first time.

In this work, we characterize nor-β-lapachone-loaded (NβL-loaded) microcapsules prepared using an emulsification/solvent extraction technique. Features such as surface morphology, particle size distribution, zeta potential, optical absorption, Raman and Fourier transform infrared spectra, thermal analysis data, drug encapsulation efficiency, drug release kinetics and in vitro cytotoxicity were studied. Spherical microcapsules with a size of 1.03 ± 0.46 μm were produced with an encapsulation efficiency of approximately 19%. Quantum DFT calculations were also performed to estimate typical interaction energies between a single nor-β-lapachone molecule and the surface of the microparticles. The NβL-loaded PLGA microcapsules exhibited a pronounced initial burst release. After the in vitro treatment with NβL-loaded microcapsules, a clear phagocytosis of the spheres was observed in a few minutes. The cytotoxic activity against a set of cancer cell lines was investigated.

Endophytic actinobacteria from the Brazilian medicinal plant Lychnophora ericoides were isolated for the first time, and the biological potential of their secondary metabolites was evaluated. A phylogenic analysis of isolated actinobacteria was accomplished with 16S rRNA gene sequencing, and the predominance of the genus Streptomyces was observed. All strains were cultured on solid rice medium, and ethanol extracts were evaluated with antimicrobial and cytotoxic assays against cancer cell lines. As a result, 92% of the extracts showed a high or moderate activity against at least one pathogenic microbial strain or cancer cell line. Based on the biological and chemical analyses of crude extracts, three endophytic strains were selected for further investigation of their chemical profiles. Sixteen compounds were isolated, and 3-hydroxy-4-methoxybenzamide (9) and 2,3-dihydro-2,2-dimethyl-4(1H)-quinazolinone (15) are reported as natural products for the first time in this study. The biological activity of the pure compounds was also assessed. Compound 15 displayed potent cytotoxic activity against all four tested cancer cell lines. Nocardamine (2) was only moderately active against two cancer cell lines but showed strong activity against Trypanosoma cruzi. Our results show that endophytic actinobacteria from L. ericoides are a promising source of bioactive compounds.

Seven β-aryl-substituted γ-alkylidene-γ-lactone analogues of rubrolides were synthesized from mucochloric acid and converted into their corresponding γ-hydroxy-γ-lactams (76–85%) by a reaction with isobutylamine and propylamine. Further dehydration of the γ-hydroxy-γ-lactams led to the corresponding (Z)- and (E)-γ-alkylidene-γ-lactams (23–45%). All compounds were fully characterized by spectroscopic methods. These 14 compounds, together with 32 other rubrolide analogues, were assayed against four human tumor cell lines (HL-60, leukaemia; HCT-116, colon; SF-295, central nervous system; and OVCAR-8, ovarian). Of the 46 compounds assayed, 7 caused a large reduction in cell viability (% RCV > 80%) in the tested cell lines and the most active compounds had halogen substituents on the aromatic ring. Compounds 10a and 14i were the most active (RC50 = 3.00 and 3.58 μM, respectively) against HL-60 and were not cytotoxic to L929 normal cells at the concentrations tested (RC50 > 50 μM). To further understand the mechanism underlying the cytotoxicity of 10a and 14i, studies involving DNA fragmentation, cell cycle analysis, phosphatidyl serine externalization and mitochondrial depolarization were performed in the HL-60 cells, using doxorubicin as a positive control. The results indicated that the cytotoxicity of 10a and 14i involved the induction of cell death by apoptosis. The cell cycle analysis showed that 14i caused the accumulation of cells in the G0/G1 phase at 2.5 and 5 μM.

Quinoxaline derivatives are reported as antineoplastic agents against a variety of human cancer cell lines, with some compounds being submitted to clinical trials. In this work, we report the synthesis, characterization and cytotoxicity potential of a new series of quinoxalinyl-hydrazones. The most cytotoxic compound was (E)-2-[2-(2-pyridin-2-ylmethylene)hydrazinyl]quinoxaline (PJOV56) that presented a time-dependent effect against HCT-116 cells. After 48 h of incubation, PJOV56 was able to induce autophagy and apoptosis of HCT-116 cells, mediated by upregulation of Beclin 1, upregulation of LC3A/B II and activation of caspase 7. Apoptosis was induced along with G0/G1 cell cycle arrest at the highest concentration of PJOV56 (6.0 µM). Thus, PJOV56 showed a dose-dependent mode of action related to induction of autophagy and apoptosis in HCT-116 cells.

Fluorescent naphthoxazoles and their boron derivatives have been synthesized and applied as superior and selective probes for endocytic pathway tracking in live cancer cells. The best fluorophores were compared with the commercially available acridine orange (co-staining experiments), showing far better selectivity.

For the first time, a fluorescent lapachone-based BODIPY was synthesised and characterised by NMR and mass spectrometry. Computational and electrochemical aspects, as well as cytotoxic activity and subcellular localisation, were studied. Confocal microscopy experiments indicated that the probe was a specific mitochondria-staining agent. These in-detail analyses were useful in understanding the cytotoxic effects and mechanism of action of this novel hybrid compound. This molecule constitutes a promising prototype owing to its potential biological activities and the new strategies aimed at mechanistic investigations in cells and in vivo, and opens up an interesting avenue of research.

Ten novel a -santonin derivatives have been synthesized as cytotoxic agents. The in vitro antitumor activity of these compounds has been evaluated against cancer cells lines. Structure-activity relationships indicate that a -methylene- g -lactone and endoperoxide functionalities play important roles in conferring cytotoxicity. The compounds 2e4, possessing the a -methylene- g -lactone group showed IC 50 values between 5.70 and 16.40 m M. Mixture of isomers 5 and 6, with the a -methylene- g -lactone and endoperoxide functionalities, displayed the greatest activity, with IC 50 values between 1.45 and 4.35 m M. The biological assays conducted with normal cells revealed that the compounds 2, 5 and 6 are selective against cancer cells lines tested. Bioactive lactones described herein and in our previous report did not cause disruption of the cell membrane in mouse erythrocytes.

Two new diterpenes, 1 and 2, together with the known ent-15-oxo-kaur-16-en-18-oic acid (3), were isolated from the bark of Croton argyrophylloides. The structural characterization of 1 and 2 was determined on the basis of spectroscopic data interpretation. The cytotoxicity of each compound was evaluated against HL-60 (leukemia), MDAMB-435 (melanoma), SF-295 (glioblastoma), and HCT-8 (colon carcinoma) human tumor cell lines and against human peripheral blood mononuclear cells. The hemolytic potential in mouse erythrocytes was also tested for 1-3.

Chalcogen-containing β-lapachone derivatives were synthesized using a straightforward methodology and evaluated against several cancer cell lines (leukaemia, human colon carcinoma, prostate, human metastatic prostate, ovarian, central nervous system and breast), showing, in some cases, IC50 values below 1 μM. The cytotoxic potential of the lapachones evaluated was also assayed using non-tumor cells: human peripheral blood mononuclear cells, two murine fibroblast lines (L929 and V79 cells) and MDCK (canine kidney epithelial cells). These compounds could provide promising new lead derivatives for anticancer drug development. This manuscript reports important findings since few authors have described C-3 substituted β-lapachone with potent antitumor activity. The methodology employed allowed the preparation of the compounds from lapachol within a few minutes in a green approach.

Novel naphthoquinone-based chalcones were prepared from the reaction between 3-bromo-nor-beta-lapachone and amino-chalcones. Lapachone derivatives are also described here. All the substances were evaluated against cancer and normal cell lines and several compounds demonstrated potent antitumor activity.

The present study evaluated the cytotoxic activity of nepetin and quercetin-3-O-glucoside, compounds isolated from the aerial parts of Eupatorium ballotaefolium. The antimitotic activity was determined as the ability to inhibit sea urchin eggs development and five tumor cells lines growth. Moreover, the activities of these compounds were compared to quercetin in the same models. Nepetin inhibited the proliferation of the five tumor cell lines, once quercetin-3-O-glucoside did not present any activity even at the highest tested concentration and quercetin only inhibited proliferation of the B16 cell line. On the sea urchin assay, nepetin and quercetin induced a dose-dependent inhibition on egg development, while quercetin-3-O-glucoside did not modify normalegg cleavage, even at the highest tested concentration (100 microg/ml).