Luis Jesús Galán-Wong

Microalgae are increasingly recognized as valuable sources of natural products with potential applications in cancer prevention and therapy due to their ability to produce structurally diverse bioactive metabolites. In the present study, methanolic extracts from microalgal strains isolated from the oligotrophic desert oasis of the Cuatro Ciénegas Basin (Mexico) were evaluated for their antioxidant activity and in vitro cytotoxic effects against human breast (MCF7), colon (Caco2), prostate (DU145), leukemia (MOLT-4), and ovarian (OVCAR-3) cancer cell lines. The isolates were identified by rbcL gene sequencing and phylogenetic analysis as members of the genera Asterarcys, Chlorella, and Neochloris. Antioxidant properties were evaluated using complementary in vitro assays, whereas cytotoxicity was assessed using the MTT assay and apoptosis-associated cellular responses were investigated by morphological analysis, acridine orange/ethidium bromide staining, and measurement of executioner caspase-3/7 activity. Neochloris sp. PA3 showed the highest total antioxidant capacity and detectable ferrous ion-chelating activity, whereas Chlorella sp. PS exhibited the strongest superoxide radical scavenging activity. Among the evaluated strains, the methanolic extract of Neochloris sp. PA3 exhibited the most favorable overall antiproliferative profile, with IC₅₀ values of 17.1, 19.0, and 19.1 µg/mL against MCF7, Caco2, and DU145 cells, respectively, while displaying markedly lower cytotoxicity toward the non-tumorigenic Vero and Detroit 548 cell lines, indicating differential cytotoxicity between the tested cancer and non-tumorigenic cell models. The extract induced time-dependent reductions in cell viability, morphological and nuclear alterations consistent with apoptotic cell death, and increased executioner caspase-3/7 activity. Collectively, these findings provide preliminary in vitro evidence of differential cytotoxicity and an apoptosis-associated cellular response in Neochloris sp. PA3-treated cancer cells.

Actinomycetes are a group of bacteria that have been reported as potential controllers of several plant pathogens and plant growth-promoting agents. This study focused on the isolation of 60 actinobacterial strains from the Cuatro Cienegas Basin, Coahuila, Mexico, with an emphasis on evaluating their potential as biocontrol agents against plant pathogens. Among the strains tested, the isolate PR69 exhibited significant in vitro antagonistic activity against eight plant pathogens, with inhibition rates ranging from 44% to 73%, including Phytophthora capsici. The genome of PR69 was sequenced and assembled. It was identified as Streptomyces by phylogenetic analysis based on concatenated multiple sequence alignments of 81 core bacterial genes. Additionally, volatile compounds produced by PR69 enhanced the growth of Arabidopsis thaliana seedlings in vitro, increasing seedling weight, primary root length, and the number of secondary roots. Furthermore, the soil treated with Streptomyces sp. PR69 effectively controlled the infection caused by the pathogen P. capsici in bell pepper plants, reducing mortality by 47% compared to plants inoculated solely with the pathogen. PR69-treated plants also showed 30% increase in fresh weight compared to untreated controls. These findings suggest that Streptomyces sp. PR69 holds promise as a bioinoculant for promoting pepper plant growth and controlling P. capsici populations.

Actinomycetes are a group of bacteria that have been reported as potential controllers of several plant pathogens and as plant growth promoting agents. This study focused on the isolation of 60 actinobacterial strains from the Cuatro Cienegas Basin, Coahuila, Mexico, with an emphasis on evaluating their potential as biocontrol agents against plant pathogens. Among the strains tested, the isolate PR69 exhibited significant in vitro antagonistic activity against eight plant pathogens, with inhibition rates ranging from 44% to 73%, including Phytophthora capsici. The genome of PR69 was sequenced and assembled, confirming its classification as a member of the genus Streptomyces through a phylogenetic analysis based on concatenated multiple sequence alignments of 81 core bacterial genes. Additionally, volatile compounds produced by PR69 enhanced the growth of Arabidopsis thaliana seedlings in vitro, increasing seedling weight, primary root length, and the number of secondary roots. Furthermore, the soil treated with Streptomyces sp. PR69 effectively controlled the infection caused by the pathogen P. capsici in bell pepper plants, reducing disease symptoms by 50% compared to plants inoculated solely with the pathogen. PR69-treated plants also showed an increase in fresh weight compared to untreated controls. These findings suggest that Streptomyces sp. PR69 holds promise as a bioinoculant for promoting pepper plant growth and controlling P. capsici populations.

Entamoeba histolytica causes amoebic liver abscess (ALA) in humans. The injury of target cells by E. histolytica includes processes controlled by the ubiquitin Ehub. Previously, we found immunodominance of Ehub glycan moieties using immunized rabbits. In this work, we analysed dominance of antibodies to the glycoprotein Ehub in the sera from 52 patients with ALA. Controls were sera from 20 healthy people living in endemic areas with a high seroprevalence of antibodies to amoebas, and 20 patients with alcoholic hepatitis (AH) to rule out the cross‐reaction of Ehub with autoantibodies induced by liver damage. Antigens were trophozoite extract, glycoprotein Ehub and the recombinant protein E. histolytica recombinant ubiquitin (rEhub). The sera from healthy volunteers and patients with AH do not have antibodies to glycoprotein Ehub. Surprisingly, only the antibodies from patients with ALA recognized the glycoprotein Ehub, and some sera gave a faint reaction with the recombinant protein, especially because evolutionarily, the ubiquitin is conserved between species. This is the first report demonstrating that antibodies to ubiquitin Ehub are induced exclusively in patients with invasive amoebiasis, and the antibody response is mainly to the glycoprotein, indicating glycans are immunodominant. Inhibitors of the Ehub glycans could be potential treatment for amoebiasis by selectively damaging trophozoites.

Background: Bacillus thuringiensis subsp. israelensis (Bti) produces insecticidal endotoxins known as Cry and Cyt. Its efficiency and specificity make it the most widely used substance as a biopesticide for controlling disease from vector insects, such as mosquitoes, responsible for important human diseases such as malaria, filariasis, dengue, and yellow fevers. To date, it is proven difficult to develop a commercial product that has more than 2 years of shelf life, and there is little information on the viability of these commercial proteins under prolonged storage conditions. Results: This study aimed to evaluate biological activity of reconstituted Bti endotoxins after 40 years of storage against the mosquito Aedes aegypti larvae. Five concentrations of Bti extracts were used for bioassays against 3rd and 4th instars of A. aegypti larvae. All reconstituted endotoxins from stored extracts showed a potency increase. The strain HD-500 from extract 3260 was the most effective insecticide (LC₅₀ = 0.0014 mg/l), followed by 3756 (LC₅₀ = 0.0037 mg/l). These strains were particularly notable, increasing their larvicidal potency one hundredfold and one thousandfold, respectively. Protein profiles in polyacrylamide gels revealed a greater presence of Cyt toxins compared to the stored Bti extracts, which maintained their activity at high concentrations. Conclusion: The reconstituted Bti strains presented a great biological activity against A. aegypti larvae, specially extract 3260 (median lethal concentration (LC₅₀) value = 0.0014 mg/l). This considerable larvicidal activity after 40 years under storage was an encouraging signal for the development of future formulation strategies regarding their useful life. The stability of extracts of stored endotoxins produced by Bti decreased significantly, particularly Cyt1A protein, which is responsible for their synergistic activity.

The toxins of Bacillus thuringiensis (Bt) have shown great potential in the control of harmful insects affecting human health and agriculture, used as the main biological agent for the formulation of bioinsecticides due to its specificity to target different insects’ orders. This has led Bt-based products to become the best-selling biological insecticides in the world since the genes encoding insecticidal proteins have been successfully used in novel insecticidal formulation, genetically engineered (GE) crops, and development of transgenic rice that produce insecticidal toxins derived from Bacillus thuringiensis. It has been proven that insecticidal activity of Bt protein crystals can prolong their toxicity in shelf life or field under specific conditions, and this can improve the use of special strains and formulations to control insect vectors of diseases. Bt toxins have shown well-documented toxicity against lepidopterans, coleopterans, hemipterans, dipterans, nematodes, Rhabditida and human cancer cells of various origins. These crystal toxins may be responsible for other novel biological properties suggesting a pluripotential nature with different specificities.

This study was carried out to determine the persistence of toxicity of fermentation extracts ofBacillus thuringiensisvar.israelensisafter more than three decades of storage. For this purpose, a population ofAedes aegyptiwas established. The mortality rate of 20 spore-crystal extracts purified using the acetone-lactose coprecipitation method was measured and evaluated by bioassays according to a modified WHO protocol. The extracts with the highest mortality rate were determined in triplicate by their LD₅₀and LD₉₈. All extracts showed toxicity at the highest tested dose (1000 ppm) and some, such as strains 3260 and 3501, still killed larvae at doses as low as 0.01 ppm. These data are surprising because no study on the activity ofB. thuringiensistoxic proteins after such a long storage time has been reported.

Thevetia peruviana (Pers.) K. Schum or Cascabela peruviana (L.) Lippold (commonly known as ayoyote, codo de fraile, lucky nut, or yellow oleander), native to Mexico and Central America, is a medicinal plant used traditionally to cure diseases like ulcers, scabies, hemorrhoids and dissolve tumors. The purpose of this study was to evaluate the cytotoxic, antiproliferative and apoptotic activity of methanolic extract of T. peruviana fruits on human cancer cell lines. The cytotoxic activity of T. peruviana methanolic extract was carried out on human breast, colorectal, prostate and lung cancer cell lines and non-tumorigenic control cells (fibroblast and Vero), using the MTT assay. For proliferation and motility, clonogenic and wound-healing assays were performed. Morphological alterations were monitored by trypan blue exclusion, as well as DNA fragmentation and AO/EB double staining was performed to evaluate apoptosis. The extract was separated using flash chromatography, and the resulting fractions were evaluated on colorectal cancer cells for their cytotoxic activity. The active fractions were further analyzed through mass spectrometry. The T. peruviana methanolic extract exhibited cytotoxic activity on four human cancer cell lines: prostate, breast, colorectal and lung, with values of IC50 1.91 ± 0.76, 5.78 ± 2.12, 6.30 ± 4.45 and 12.04 ± 3.43 μg/mL, respectively. The extract caused a significant reduction of cell motility and colony formation on all evaluated cancer cell lines. In addition, morphological examination displayed cell size reduction, membrane blebbing and detachment of cells, compared to non-treated cancer cell lines. The T. peruviana extract induced apoptotic cell death, which was confirmed by DNA fragmentation and AO/EB double staining. Fractions 4 and 5 showed the most effective cytotoxic activity and their MS analysis revealed the presence of the secondary metabolites: thevetiaflavone and cardiac glycosides. T. peruviana extract has potential as natural anti-cancer product with critical effects in the proliferation, motility, and adhesion of human breast and colorectal cancer cells, and apoptosis induction in human prostate and lung cancer cell lines, with minimal effects on non-tumorigenic cell lines.