The search for plants with anticancer activity: pitfalls at the early stages

Functional Properties of Dunaliella salina and Its Positive Effect on Probiotics

The unicellular green microalga Dunaliella is a potential source of a wide range of nutritionally important compounds applicable to the food industry. The aim of this study was to assess the effect of Dunaliella salina dried biomass on the growth and adherence of 10 strains of Lactobacillus, Lacticaseibacillus, and Bifidobacterium. The immunomodulatory, antioxidant, and cytotoxic effects of D. salina on human peripheral mononuclear cells and simulated intestinal epithelial cell lines Caco-2 and HT-29 were evaluated. Furthermore, the hypocholesterolemic effects of the microalgae on lipid metabolism in rats fed a high-fat diet were analyzed. The addition of D. salina biomass had a positive effect on the growth of nine out of 10 probiotics and promoted the adherence of three bifidobacteria strains to human cell lines. The antioxidant and immunomodulatory properties of D. salina were concentration-dependent. The inflammatory cytokines (TNF-α and IL-6) were significantly increased following Dunaliella stimulation at the lowest concentration (0.5% w/v). Eight week supplementation of D. salina to the diet of hypercholesteromic rats significantly decreased the serum concentrations of LDL-C, VLDL, IDL-B, and IDL-C. D. salina is not cytotoxic in intestinal cell models; it promotes adherence of selected bifidobacteria, it affords immunomodulatory and antioxidant effects, and its addition to diets may help decrease atherosclerosis risk factors.

Addressing artifacts of colorimetric anticancer assays for plant-based drug development

Cancer has become the silent killer in less-developed countries and the most significant cause of morbidity worldwide. The accessible and frequently used treatments include surgery, radiotherapy, chemotherapy, and immunotherapy. Chemotherapeutic drugs traditionally involve using plant-based medications either in the form of isolated compounds or as scaffolds for synthetic drugs. To launch a drug in the market, it has to pass through several intricate steps. The multidrug resistance in cancers calls for novel drug discovery and development. Every year anticancer potential of several plant-based compounds and extracts is reported but only a few advances to clinical trials. The false-positive or negative results impact the progress of the cell-based anticancer assays. There are several cell-based assays but the widely used include MTT, MTS, and XTT. In this article, we have discussed various pitfalls and workable solutions.

Functional Properties of Chlorella vulgaris, Colostrum, and Bifidobacteria, and Their Potential for Application in Functional Foods

The market for new functional foods and food supplements is rapidly evolving, with a current emphasis on using natural sources. Algae, probiotics, and colostrum are rich sources of nutrients and bioactive compounds with positive effects on human and animal health. To determine the potential for developing new functional foods combining these components, we evaluated their synergistic effects. We assessed the growth of selected bifidobacteria in a medium supplemented with Chlorella vulgaris and its immunomodulatory and cytotoxic effects on the human peripheral mononuclear cells and colon cancer cell lines Caco-2 and HT29. The hypocholesterolemic effects of Chlorella powder and bovine colostrum fermented by Bifidobacterium animalis subsp. lactis BB12® on lipid metabolism in rats fed a high-fat diet were also determined. Chlorella addition promoted Bifidobacteria growth, with significantly increased inflammatory cytokine (TNF-α and IL-6) levels following 1.0% (w/v) Chlorella stimulation. Rats fed diets containing fermented colostrum with 0.5% (w/v) added Chlorella powder exhibited significantly decreased triglyceride, very low-density lipoprotein, and alanine and aspartate aminotransferase levels, compared to those of the control group. These results support that C. vulgaris is not cytotoxic in intestinal cell models and affords prebiotic and immunomodulatory effects, as well as synergistic triglyceride-lowering effects with bovine colostrum and B. animalis subsp. lactis BB-12.

All that glitters is not gold: Panning cytotoxic natural products and derivatives with a fused tricyclic backbone by the estimation of their leadlikeness for cancer treatment

Tricyclic compounds call the attention because of their pharmacological properties, and are considered a preferred platform for the development of drugs. Especially, in cancer treatment, these planar compounds are known for their ability to stack with DNA base pairs, acting as intercalators. In this sense, natural products (NPs) are a prodigal source of polycyclic compounds, comprising classes, such as carbolines, anthraquinones and xanthones. However, most of these compounds lack suitable physico-chemical properties, compatible to oral bioaviability. In this perspective, this paper aims to overview the role of tricyclic cores in the development of cytotoxic compounds, focusing on the leadlikeness estimation of the most prominent NP classes and their synthetic derivatives.

Assessment of the cytotoxic potential of an aqueous-ethanolic extract from Thalassia testudinum angiosperm marine grown in the Caribbean Sea

OBJECTIVES

Reported antioxidant, anti-inflammatory and neuroprotective properties for one aqueous-ethanolic extract from Thalassia testudinum which grows in the Caribbean Sea compelled us to explore about extract cytotoxic effects.

METHODS

Cell viability was assayed on tumour (HepG2, PC12, Caco-2 and 4T1) and non-tumour (VERO, 3T3, CHO, MCDK and BHK2) cell lines. The extract effects upon primary cultures of rat and human hepatocytes and human lymphocytes were assayed.

KEY FINDINGS

The extract exhibited cytotoxicity against cancer cells compared to normal cells, and the IC₅₀ values were 102 μg/ml for HepG2, 135 μg/ml for PC12, 165 μg/ml for Caco-2 and 129 μg/ml for 4T1 cells after 48 h, whereas IC₅₀ could not be calculated for normal cells. Additional data from a high-content screening multiparametric assay indicated that after 24-h exposure, the extract (up to 100 μg/ml) induced death in HepG2 cells through oxidative stress-associated mechanism, DNA damage and hypercalcaemia. Comet assay corroborated extract-induced DNA damage.

CONCLUSIONS

Thalassia testudinum extract is more cytotoxic and produced more DNA damage on human hepatoma cells than to other non-tumour cells. A possible mechanism is suggested for extract-induced cytotoxicity based on oxidative stress, nuclear damage and hypercalcaemia in HepG2 cells. T. testudinum may be a source for antitumour agents.

Solidification of hydatid cyst fluid with an injectable chitosan/carboxymethylcellulose/β-glycerophosphate hydrogel for effective control of spillage during aspiration of hydatid cysts

Cystic echinococcosis (CE)/hydatid cyst is one of the most important helminthic diseases in the world. The treatment of hydatid cyst ranges from surgical intervention to chemotherapy, although the efficacy of chemotherapy is still unclear. Postoperative complication which results from the spillage of cysts during surgical operation is one of the most important concerns in surgical treatment of hydatid cyst. The aim of the current study was to solidify the hydatid cyst fluid (HCF) with an injectable and thermosensitive chitosan (CS)/carboxymethyl cellulose (CMC)/β-glycerol phosphate (BGP) hydrogel for effective control of spillage during the aspiration of hydatid cysts. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), water uptake, rheological analysis, and Alamar Blue cytotoxicity assay were employed to characterize the hydrogel. A five level with three times replication at the central point using a central composite design (CCD), which is a response surface methodology (RSM), was used to optimize the experimental conditions. Assessment of the produced hydrogel showed that the intermolecular interactions of amino groups of chitosan and hydrogen groups of CMC were correctively established and appreciable swelling with a good strength was obtained. Hydrogels morphology had a porous structure. Rheological analysis showed that CS/CMC/BGP blends had a phase transition (32-35 °C) of sol-gel close to the body temperature. Alamar Blue cytotoxicity assay showed that CS (1.75%)/CMC (1.4%)/BGP (2.9%) had IC50 values of 0.598, 0.235 and 0.138 (µg/µL) for 24, 48 and 72 h, which indicated that the produced polymer solution had no significant cytotoxic effect for human fibroblast cell line. In vitro injection of the polymer solution of CS/CMC/BGP with CS/CMC ratio of 1.75/1.4 was done on HCF (1 mL polymer solution to 3 mL of HCF) at 37 °C with a final concentration of 2.9% for BGP resulting in solidification of HCF in less than 45 min.

High-content cell death imaging using quantum dot-based TIRF microscopy for the determination of anticancer activity against breast cancer stem cell

We report a two color monitoring of drug-induced cell deaths using total internal reflection fluorescence (TIRF) as a novel method to determine anticancer activity. Instead of cancer cells, breast cancer stem cells (CSCs) were directly tested in the present assay to determine the effective concentration (EC₅₀ ) values of camptothecin and cisplatin. Phosphatidylserine and HMGB1 protein were concurrently detected to observe apoptotic and necrotic cell death induced by anticancer drugs using quantum dot (Qdot)-antibody conjugates. Only 50-to-100 breast CSCs were consumed at each cell chamber due to the high sensitivity of Qdot-based TIRF. The high sensitivity of Qdot-based TIRF, that enables the consumption of a small number of cells, is advantageous for cost-effective large-scale drug screening. In addition, unlike MTT assay, this approach can provide a more uniform range of EC₅₀ values because the average values of single breast CSCs fluorescence intensities are observed to acquire EC₅₀ values as a function of dose. This research successfully demonstrated the possibility that Qdot-based TIRF can be widely used as an improved alternative to MTT assay for the determination of anticancer drug efficacies.

The chemopotential effect of Annona muricata leaves against azoxymethane-induced colonic aberrant crypt foci in rats and the apoptotic effect of Acetogenin Annomuricin E in HT-29 cells: a bioassay-guided approach

Annona muricata has been used in folk medicine for the treatment of cancer and tumors. This study evaluated the chemopreventive properties of an ethyl acetate extract of A. muricata leaves (EEAML) on azoxymethane-induced colonic aberrant crypt foci (ACF) in rats. Moreover, the cytotoxic compound of EEAML (Annomuricin E) was isolated, and its apoptosis-inducing effect was investigated against HT-29 colon cancer cell line using a bioassay-guided approach. This experiment was performed on five groups of rats: negative control, cancer control, EEAML (250 mg/kg), EEAML (500 mg/kg) and positive control (5-fluorouracil). Methylene blue staining of colorectal specimens showed that application of EEAML at both doses significantly reduced the colonic ACF formation compared with the cancer control group. Immunohistochemistry analysis showed the down-regulation of PCNA and Bcl-2 proteins and the up-regulation of Bax protein after administration of EEAML compared with the cancer control group. In addition, an increase in the levels of enzymatic antioxidants and a decrease in the malondialdehyde level of the colon tissue homogenates were observed, suggesting the suppression of lipid peroxidation. Annomuricin E inhibited the growth of HT-29 cells with an IC50 value of 1.62 ± 0.24 μg/ml after 48 h. The cytotoxic effect of annomuricin E was further substantiated by G1 cell cycle arrest and early apoptosis induction in HT-29 cells. Annomuricin E triggered mitochondria-initiated events, including the dissipation of the mitochondrial membrane potential and the leakage of cytochrome c from the mitochondria. Prior to these events, annomuricin E activated caspase 3/7 and caspase 9. Upstream, annomuricin E induced a time-dependent upregulation of Bax and downregulation of Bcl-2 at the mRNA and protein levels. In conclusion, these findings substantiate the usage of A. muricata leaves in ethnomedicine against cancer and highlight annomuricin E as one of the contributing compounds in the anticancer activity of A. muricata leaves.