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.

Endophytic fungi have become potential sources of antitumor agents, particularly against antineoplastic-resistant cancer cells, with marginal or nil adverse effects for the oncological patient. Endophytic fungi were isolated from stems of the Lophocereus marginatus cactus, commonly found in Mexico. Methanol extracts were then obtained from fungus liquid cultures and their effects on tumor cell growth against murine lymphoma (L5178Y-R), human colorectal adenocarcinoma (HT-29), and human breast cancer (MCF-7) cells were evaluated at concentrations ranging from 31 µg/mL to 250 µg/mL via the colorimetric 3- [4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide reduction assay, using monkey kidney epithelial (MA-104) and human peripheral mononuclear (PBMC) cells as controls. Furthermore, we obtained the IC₅₀ and the selectivity index (SI) was calculated from the IC₅₀ ratio of normal and tumor cells. In addition, molecular identification of fungi showing cytotoxic activity was determined, using internal transcribed spacer molecular markers. PME-H001, PME-H002, PME-H005, PME-H007, and PME-H008 filamentous fungus strain extracts showed significant (p < 0.05) tumor cell growth inhibition. In particular, they significantly (p < 0.05) inhibited L5178Y-R cell growth, whereas the least susceptible cell line was HT-29. The endophytic strain PME-H008 of Cladosporium sp. caused the highest growth inhibition percentage against L5178Y-R and HT-29 cells with 96.6% (p < 0.01) and 42.5% (p < 0.05) respectively, and the highest SIs against L5178Y-R cells with 2.4 and 2.9 for MA-104 and PBMCs, respectively, whereas the PME-H005 extract showed SIs of 2.77 and 1.5 against MCF-7 and L5178Y-R cells, respectively, as compared with PBMCs. In addition, the endophytic strain PME-H007 of Metarhizium anisopliae caused the highest percentage of growth inhibition (p < 0.01) against MCF-7 cells with 55.8% at 250 µg/mL. We demonstrated in vitro antitumor effects of L. marginatus endophytic fungi. Further research will involve the isolation and in vivo testing of bioactive compounds.

Plant-associated microorganisms represent a potential source of new antitumor compounds. The aim of the present study was to isolate endophytic and rhizosphere Gram-positive bacteria from Ibervillea sonorae and produce extracts with antitumor activity. Methanol and ethyl acetate extracts were obtained from 28 d bacterial fermentation, after which murine L5178Y-R lymphoma cells growth inhibition was evaluated at concentrations ranging from 15.62 µg/mL to 500 µg/mL by the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide reduction colorimetric assay. IC₅₀ and the selectivity index (SI) were calculated and compared with healthy control human peripheral blood mononuclear cells (PBMC). Identification of the isolated strains was performed using the 16S ribosomal gene and by MALDI-TOF MS mass spectrometry. The endophytic and rhizosphere bacterial extracts from strains ISE-B22, ISE-B26, ISE-B27, ISS-A01, ISS-A06, and ISS-A16 showed significant (p < 0.05) L5178Y-R cell growth inhibition, compared with an untreated control. The rhizosphere Micromonospora echinospora isolate ISS-A16 showed the highest (90.48%) percentage of lymphoma cells growth inhibition and SI (19.1) for PBMC, whereas the Bacillus subtilis ISE-B26 isolate caused significant (p < 0.01) growth inhibition (84.32%) and a SI of 5.2. Taken together, results of the present study evidenced antitumor effects by I. sonorae endophytic and rhizosphere bacteria culture extracts. Further research will involve the elucidation of the compounds that exert the antitumor activity and their evaluation in pre-clinical studies.

Cancer belongs to a group of diseases characterized by uncontrolled cell growth. The search for new effective treatments for cancer has led to the discovery of different molecules from plants, bacteria, and fungi with pharmacological use. Plant endophytic fungi are large producers of metabolites with antitumor properties. We aimed to evaluate the in vitro and in vivo antitumor potential of extracts from Lophocereus marginatus endophytic fungi. We obtained ethyl acetate and hexane extracts from the L. marginatus endophytes Metarhizium anisopliae and Aspergillus versicolor and evaluated their antitumor activity against murine L5178Y-R lymphoma cells and human peripheral blood mononuclear cells, using the 3-(4,5-dimethylthiazol-2-yl)-2-diphenyltetrazolium bromide reduction colorimetric technique. M. anisopliae and A. versicolor ethyl acetate extracts showed IC₅₀ values of 9.168 ± 1.21 μg/mL and 13.51 ± 1.62, respectively, and selectivity indices > 30. We also observed that the maximum tolerated dose (100 mg/kg) of ethyl acetate extracts and the vehicle in BALB/c mice did not cause hepatotoxicity. In addition, we evaluated the effects of ethyl acetate extracts on survival and tumor volume in the L5178Y-R lymphoma tumor model. An increase in survival (17 d) was observed in mice treated with A. versicolor extract. Furthermore, it did not increase tumor volume during 10 d, as compared with the control groups without treatment, vehicle, and M. anisopliae extract, which had a maximum survival of 10 d. A. versicolor ethyl acetate extract showed in vitro and in vivo antitumor activity against lymphoma L5178Y-R, increasing mice survival.

Culture conditions affect the production of secondary metabolites in endophytic fungi. Therefore, the aim of the present study was to evaluate the yield and anticancer and antioxidant activity of endophytic fungi extracts from the cactus Lophocereus marginatus, under different culture conditions. The strains Penicillium citrinum, Aspergillus versicolor, Metarhizium anisopliae, and Cladosporium sp. were fermented in different culture media (potato dextrose agar, Czapeck broth, and malt broth), types of inoculums (spore or mycelium), and shaking conditions (150 rpm or static) for one week. Methanol extracts were obtained from mycelia, which was followed by determining their yields and evaluating their effect on L5178Y-R murine lymphoma cells growth and human peripheral blood mononuclear cells (PBMCs) viability, using the 3-[4,5dimethylthiazol-2-yl]2,5-diphenyl tetrazolium bromide reduction colorimetric assay. In addition, antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazyl test. We determined the half-maximal inhibitory concentration (IC₅₀) values of tumor cell growth inhibition, the selectivity index (SI), and the antioxidant activity, as compared with the healthy cells control. The best yields were obtained with the Czapeck broth medium in all the evaluated strains, reaching values of 50.3%. Of the 48 extracts evaluated, only seven significantly (p < 0.01) inhibited tumor cell growth (IC₅₀ < 250 µg/mL). A. versicolor extract showed the highest anticancer activity, after culturing spores (IC₅₀ = 49.62 µg/mL; SI = 15.8) or mycelium (IC₅₀ = 69.67 µg/mL; SI = 12.2) in malt broth, under static conditions. Extracts did not present significant antioxidant activity. In conclusion, we showed that culture conditions influenced the anticancer activity of L. marginatus endophytic fungi.

Identification of new sources of compounds with anticancer and antioxidant potential is essential for cancer treatment. Rhizospheric bacteria have emerged as a promising source of these agents. This study is aimed at investigating the anticancer and antioxidant properties of bacteria isolated from the rhizosphere of Lophocereus marginatus . Six rhizobacteria of L. marginatus were isolated and molecularly identified by sequencing the 16S rRNA gene and MALDI‐TOF. We evaluated the inhibitory activity of methanol (MeOH) and ethyl acetate (EtOAc) extracts obtained from rhizobacteria against the murine lymphoma cell line L5178Y‐R, as well as normal Vero monkey kidney cells and peripheral blood mononuclear cells (PBMCs). Compared with those of normal cells, the MeOH extract of Paenibacillus sp. PMS‐B023 showed selective anticancer activity against lymphoma, with 50% inhibitory concentration (IC ₅₀ ) values of 117.5 μ g/mL and a selectivity index (SI) > 2.1, as compared with those of normal cells. L‐Pro‐L‐Val cycle, gageostatin B, cinnamic acid, parvifloracin, daidzein, genistein, actinomycin D, actinomycin Y4, and surfactin C were detected in the MeOH extract, which may be responsible for its antilymphoma activity. We did not find significant antioxidant activity in any of the extracts evaluated using the 2,2‐diphenyl‐1‐picrylhydrazyl technique (IC ₅₀ > 250  μ g/mL). The results showed that Paenibacillus sp. PMS‐B023 has antitumor potential and selective activity against L5178Y‐R lymphoma cells. The presence of anticancer compounds was also demonstrated, as previously described in the literature.