In Vitro Antitumor Activity of Endophytic and Rhizosphere Gram-Positive Bacteria from Ibervillea sonorae (S. Watson) Greene against L5178Y-R Lymphoma Cells

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.

Chitosan oligosaccharide alleviates the growth inhibition caused by physcion and synergistically enhances resilience in maize seedlings

The use of biopesticides has gradually become essential to ensure food security and sustainable agricultural production. Nevertheless, the use of single biopesticides is frequently suboptimal in agricultural production given the diversity of biotic and abiotic stresses. The present study investigated the effects of two biopesticides, physcion and chitosan-oligosaccharide (COS), alone and in combination, on growth regulation and antioxidant potential of maize seedlings by seed coating. As suggested from the results, physcion significantly inhibited the growth of the shoots of maize seedlings due to the elevated respiration rate. However, COS significantly reduced the growth inhibition induced by physcion in maize seedlings by lowering the respiration rate and increasing the content of photosynthetic pigments and root vigor, which accounted for lower consumption of photosynthesis products, a higher photosynthetic rate and a greater nutrient absorption rate. Thus, an improved growth was identified. As indicated from the in-depth research, the application of physcion and COS combination is more effective in down-regulated the malondialdehyde (MDA) content by facilitating the activities of the antioxidative enzymes (i.e., superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (G-POD)). Such results indicated that the combined use of physcion and COS neither affected the normal growth of maize seedlings, but also synergistically improved the antioxidant potential of the maize plants, resulting in plants with high stress resistance. Thus, the combined use of physcion and COS by seed coating in maize production has great potential to ensure yield and sustainable production of maize.

Amikacin potentiator activity of zinc complexed to a pyrithione derivative with enhanced solubility

Resistance to amikacin in Gram-negatives is usually mediated by the 6'-N-acetyltransferase type Ib [AAC(6')-Ib], which catalyzes the transfer of an acetyl group from acetyl CoA to the 6' position of the antibiotic molecule. A path to continue the effective use of amikacin against resistant infections is to combine it with inhibitors of the inactivating reaction. We have recently observed that addition of Zn2+ to in-vitro enzymatic reactions, obliterates acetylation of the acceptor antibiotic. Furthermore, when added to amikacin-containing culture medium in complex to ionophores such as pyrithione (ZnPT), it prevents the growth of resistant strains. An undesired property of ZnPT is its poor water-solubility, a problem that currently affects a large percentage of newly designed drugs. Water-solubility helps drugs to dissolve in body fluids and be transported to the target location. We tested a pyrithione derivative described previously (Magda et al. Cancer Res 68:5318–5325, 2008) that contains the amphoteric group di(ethyleneglycol)-methyl ether at position 5 (compound 5002), a modification that enhances the solubility. Compound 5002 in complex with zinc (Zn5002) was tested to assess growth inhibition of amikacin-resistant Acinetobacter baumannii and Klebsiella pneumoniae strains in the presence of the antibiotic. Zn5002 complexes in combination with amikacin at different concentrations completely inhibited growth of the tested strains. However, the concentrations needed to achieve growth inhibition were higher than those required to achieve the same results using ZnPT. Time-kill assays showed that the effect of the combination amikacin/Zn5002 was bactericidal. These results indicate that derivatives of pyrithione with enhanced water-solubility, a property that would make them drugs with better bioavailability and absorption, are a viable option for designing inhibitors of the resistance to amikacin mediated by AAC(6')-Ib, an enzyme commonly found in the clinics.

Antimalarial Activity of Ethanol Extract of Kelakai Leaves (Stenochlaena palustris) to Parasitemia and Splenomegaly in BALB/c Mice Infected with Plasmodium berghei ANKA

Introduction: Malaria is one of global health problems. Splenomegaly is one of malaria symptoms. Antimalarial drug resistance had been reported. Alternative treatment is by using traditional medicinal plants such as kelakai (Stenochlaena palustris). Kelakai contains alkaloid and flavonoid which had been reported to have antimalarial activity. The aim of this study was to discover antimalarial activity of ethanol extract of kelakai leaves to parasitemia and splenomegaly of Plasmodium berghei ANKA in infected BALB/c mice.Methods: This study was based on a modified Peter test using BALB/c mice infected with P. berghei ANKA treated with ethanol extract of kelakai leaves, with chloroquine diphosphate as a positive control. The negative control was P. berghei ANKA infected mice without any additional treatment. Administration of ethanol extract of kelakai leaves was performed for 4 days with a serial doses of 100, 10, and 1 mg/kg body weight. The positive control was given chloroquine diphosphate 20 mg/kg body weight. Parasitemia was observed daily prior to the calculation of the percentage of parasite growth and parasite growth inhibition. At the end of the test, the mice were sacrificed and spleens were isolated to measure their sizes. Probit analysis was performed to obtain ED50 to find the effect of extract in parasite killing by 50%. Spearman test was performed to analyze the correlation of doses of extract and splenomegaly.Results: Parasitemia growth inhibition was directly proportional to the dose. Higher parasitemia inhibition was obtained at higher doses and vice versa. Result of probit analysis showed an ED50 was 77.05 mg/kg body weight. Statistical analysis resulted in insignificant correlation between doses and splenomegaly p = 1.0 (significancy < 0.05).Conclusion: Ethanol extract of kelakai leaves possessed good antimalarial activity and there was no correlation between extract doses and splenomegaly in Plasmodium berghei ANKA-infected mice.