A novel cytosporone 3-Heptyl-4,6-dihydroxy-3H-isobenzofuran-1-one: synthesis; toxicological, apoptotic and immunomodulatory properties; and potentiation of mutagenic damage

Biosynthesis of Cytosporones in Leotiomycetous Filamentous Fungi

Polyketides with the isochroman-3-one pharmacophore are rare among fungal natural products as their biosynthesis requires an unorthodox S-type aromatic ring cyclization. Genome mining uncovered a conserved gene cluster in select leotiomycetous fungi that encodes the biosynthesis of cytosporones, including isochroman-3-one congeners. Combinatorial biosynthesis in total biosynthetic and biocatalytic formats in Saccharomyces cerevisiae and in vitro reconstitution of key reactions with purified enzymes revealed how cytosporone structural and bioactivity diversity is generated. The S-type acyl dihydroxyphenylacetic acid (ADA) core of cytosporones is assembled by a collaborating polyketide synthase pair. Thioesterase domain-catalyzed transesterification releases ADA esters, some of which are known Nur77 modulators. Alternatively, hydrolytic release allows C6 hydroxylation by a flavin-dependent monooxygenase, yielding a trihydroxybenzene moiety. Reduction of the C9 carbonyl by a short chain dehydrogenase/reductase initiates isochroman-3-one formation, affording cytosporones with cytotoxic and antimicrobial activity. Enoyl di- or trihydroxyphenylacetic acids are generated as shunt products, while isocroman-3,4-diones are formed by autoxidation. The cytosporone pathway offers novel polyketide biosynthetic enzymes for combinatorial synthetic biology to advance the production of "unnatural" natural products for drug discovery.

Chemotherapeutic Mechanism of Action of the Synthetic Resorcinolic Methyl 3,5-dimethoxy-2-octanoylbenzoate

Resorcinolic lipids are described as potential examples of selective chemotherapeutic adjuvants that can enhance the effects of cyclophosphamide (CYC) while promoting cell death without causing DNA damage. Therefore, the current study attempted to describe how the resorcinolic lipid methyl 3,5-dimethoxy-2-octanoylbenzoate (AMS35BB) interacted with DNA (DNA docking) and how this compound affected genetic toxicology models and other biological characteristics when combined with CYC. We observed that AMS35BB, used alone (7.5 and 10 mg/kg), increases the frequency of genomic damage (comet assay) but not chromosomal damage (micronuclei assay), lowers phagocytosis, and promotes cell death in Swiss male mice. When used in association with CYC, AMS35BB can reduce the risk of genomic damage by up to 33.8% as well as chromosomal damage, splenic phagocytosis, cell death, and lymphocyte frequency. Molecular docking showed that AMS35BB had a higher affinity than the active metabolite of CYC for binding to the DNA double helix major groove. As a result, AMS35BB has the potential to be both an adjuvant when used in association with CYC and a therapeutic candidate for the development of a selective chemotherapeutic drug.

Absence of maternal-fetal adverse effects of Alternanthera littoralis P. Beauv. following treatment during pregnancy in mice

Alternanthera littoralis P. Beauv is a plant native to Brazil that exhibits various beneficial activities including antioxidant, antibacterial, antifungal, antiprotozoal, anti-hyperalgesic, and anti-inflammatory properties. The aim of this study was to assess the impact of the ethanol extract of Alternanthera littoralis (EEAl) on reproductive outcomes, embryofetal development, and DNA integrity of pregnant female mice. Pregnant Swiss female mice were randomly assigned to three experimental groups (n = 10): controls were administered either 1% Tween 80 (vehicle), EEAl 100 mg/kg or EEAl 1000 mg/kg. Treatment was administered through gavage during the gestational period until day 18. On gestational days 16, 17, and 18, a peripheral blood sample from the tail vein was obtained for DNA integrity analysis (micronucleus test). After the last collection, animals were euthanized by cervical dislocation. Maternal organs and fetuses were collected, weighed, and subsequently analyzed. Reproductive outcome parameters were assessed by measurement of number of implants, live fetuses, and resorptions. Embryonic development was determined by adequacy of weight for gestational age as well as determination of external, visceral, and skeletal malformations. Data demonstrated that EEAl did not produce maternal toxicity at either dose associated with no marked alterations in any of the reproductive outcome parameters including implantation sites, live/dead fetuses ratio, fetal viability, post-implantation losses, resorptions, and resorption rate. However, EEAl 1000 group reduced embryofetal development by lowering placental weight. In addition, there was an increase in the frequency of external and skeletal malformations in the EEAl 1000 group, which could not be attributed to extract exposure as these values were within control levels. Based upon our findings, evidence indicates that the EEAl at the concentrations employed in our study may be considered safe for use during pregnancy and extracts of this plant show potential for development of phytomedicines to be used in pregnancy.

3-Heptylidene-4,6-Dimethoxy-3H-Isobenzofuran-1-One Is Genotoxic, Increases the Frequency of Cell Death, and Potentiates the Effects of Cyclophosphamide and Cisplatin

3-heptylidene-4,6-dimethoxy-3H-isobenzofuran-1-one (Phthalide 1) is the precursor of three resorcinol lipids that have been described as potential chemotherapeutic agents and capable of potentiating the effects of cyclophosphamide. In this study, we evaluated the genotoxic potential, cell-killing potential, and interactions with cyclophosphamide and cisplatin of phthalide 1. Twelve groups were created from 120 mice: Negative Control, cyclophosphamide (100 mg/kg), cisplatin (6 mg/kg), Phthalide 1 (5, 10 and 20 mg/kg), and associations of 1 with cyclophosphamide and 1 with cisplatin. The results demonstrate that 1 increases (p < 0.05) the frequency of chromosomal damage, liver and kidney cell death, and splenic phagocytosis. The association of 1 with cyclophosphamide and cisplatin demonstrated a chemopreventive effect and, therefore, a reduction (p < 0.05) in the frequency of chromosomal damage. However, cell death and splenic phagocytosis did not suffer significant variations. As a result of the above, 1 has potential chemotherapeutic application and may be a candidate for developing a new generation of chemotherapeutics. In addition, it has characteristics to be used as a chemotherapy adjuvant in association with cyclophosphamide and cisplatin since it increases the frequency of cell death induced by chemotherapy. We also reported that the chemopreventive effect of 1, in association with cyclophosphamide and cisplatin, can prevent adverse effects (induction of DNA damage in non-tumor cells) without interfering with the mode of action of chemotherapy drugs and, therefore, without reducing the induction of cell death.

ZIM, a Norbornene Derived from 4-Aminoantipyrine, Induces DNA Damage and Cell Death but in Association Reduces the Effect of Commercial Chemotherapeutics

Cancer incidence is increasing, and the drugs are not very selective. These drugs cause adverse effects, and the cells become resistant. Therefore, new drugs are needed. Here, we evaluated the effects of ZIM, a candidate for chemotherapy, and 4-AA alone and in association with commercial chemotherapeutic agents. Subsequently, the results of ZIM and 4-AA were compared. Male Swiss mice were treated with doses of 12, 24, or 48 mg/kg ZIM or 4-AA alone or in association with cisplatin (6 mg/kg), doxorubicin (16 mg/kg), and cyclophosphamide (100 mg/kg). Biometric parameters, DNA damage (comet and micronuclei), cell death, and splenic phagocytosis were evaluated. DNA docking was also performed to confirm the possible interactions of ZIM and 4-AA with DNA. 4-AA has been shown to have low genotoxic potential, increase the frequency of cell death, and activate phagocytosis. ZIM causes genomic and chromosomal damage in addition to causing cell death and activating phagocytosis. In association with chemotherapeutical agents, both 4-AA and ZIM have a chemopreventive effect and, therefore, reduce the frequency of DNA damage, cell death, and splenic phagocytosis. The association of 4-AA and ZIM with commercial chemotherapeutic agents increased the frequency of lymphocytes compared to chemotherapeutic agents alone. Molecular docking demonstrated that ZIM has more affinity for DNA than 4-AA and its precursors (1 and 2). This was confirmed by the lower interaction energy of the complex (-119.83 kcal/mol). ZIM can break the DNA molecule and, therefore, its chemotherapeutic effect can be related to DNA damage. It is considered that ZIM has chemotherapeutic potential. However, it should not be used in combination with cisplatin, doxorubicin, and cyclophosphamide as it reduces the effects of these drugs.

Antimicrobial activity of plant extracts against carbapenem-producing Klebsiella pneumoniae and in vivo toxicological assessment

The global spread of multidrug-resistant strains has prompted the scientific community to explore novel sources of chemicals with antimicrobial activity. The aim of the study was to examine the antimicrobial activity in vitro of 28 extracts against carbapenem-producing Klebsiella pneumoniae, individually and in combination with antibiotics and in vivo toxicological assessment of the most active product. The multi-resistant K. pneumoniae strain was submitted for phenotypic and molecular characterization. The antibacterial activity of 28 plant extracts was evaluated alone and in combination with antibiotics against this strain through the agar disk diffusion. Of these, 16 extracts showed synergism against carbapenem-producing K. pneumoniae, being that B. crassifolia extract exhibited synergism with three antibiotics. Based on this assessment, B. crassifolia-extract-induced toxicity on Swiss male mice was evaluated by administering this extract and subsequently determining apoptosis and splenic phagocytosis using the comet and micronucleus assays. The results of this study showed that B. crassifolia extract had synergistic activity promising and groups treated with B. crassifolia exhibited no genotoxic or mutagenic activity, indicating that B. crassifolia extract exerted beneficial effects and appeared safe to use at the studied concentrations.

Genotoxicity assessment of saline extract from Pilosocereus gounellei (Cactaceae) and its chemopreventive effect against cyclophosphamide-induced DNA damage

Pilosocereus gounellei (Cactaceae) is used to treat wounds and inflammation. In this study, we evaluated whether the saline extract from its stem would have genotoxic or anti-genotoxic effects. In the genotoxicity evaluation, mice received the extract (500, 1,000, or 2,000 mg/kg) orally while negative and positive controls were treated with saline solution (0.9% NaCl) per os and cyclophosphamide (CPA, 80 mg/kg i.p.), respectively. In the anti-genotoxicity assay, using other animals, treatments were carried out by administering the extract (500, 1,000 or 2,000 mg/kg) or saline solution (negative control) per os and then CPA (80 mg/kg i.p.) 1 h later. Genotoxic effects were evaluated by micronucleus test and comet assay using peripheral blood and bone marrow cells. Oral administration of only the extract at 500 and 1,000 mg/kg did not result in genotoxicity. A slight increase in the incidence of micronucleus was observed at the highest dose (2,000 mg/kg). Administration of the extract before CPA reduced the micronucleated polychromatic erythrocytes (MNPCE) number by 49.07–71.43%, and DNA fragmentation in peripheral blood (85.04–94.44%) and bone marrow (87.43–92.70%) cells also decreased. In conclusion, when administered orally at the tested doses, the extract is genotoxically safe, being cautious in doses above 1,000 mg/kg, and has a protective effect against CPA-induced DNA damage.

Assessment of the toxicogenic effects and cell death potential of the ester (Z)-methyl 4-((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)amino)-4-oxobut-2-anoate in combination with cisplatin, cyclophosphamide and doxorubicin

Despite rapid advances in both the early detection and treatment of cancer, the mortality from this disease remains high, which justifies the development of new products that are more selective and effective and have fewer side effects. Accordingly, a novel ester was synthesized that contains two pharmacophores with important biological activities: (I) 4-aminoantipyrine, which has anti-inflammatory and antioxidant effects, and (II) the pharmacophore 1,4-dioxo-butenyl, which has cytotoxic activity. When administered alone, this compound is non-genotoxic, and it does not cause an increasing in splenic phagocytosis. Nevertheless, it can induce cell death. When administered in combination with commercial chemotherapeutic agents, such as doxorubicin, cisplatin, and cyclophosphamide, the ester shows antigenotoxic activity and decreases phagocytosis and reduces the potential to cause cell death. These results indicate that the compound should not be used in combination with chemotherapeutic agents that exert their effect through DNA damage, an important feature of antitumor drugs.

Resorcinolic lipid 3-heptyl-3,4,6-trimethoxy-3H-isobenzofuran-1-one is a strategy for melanoma treatment

AIMS

Previous studies performed by our research group indicated that cytosporone analogues are capable of prevent or repair DNA damages. This work presents the evaluation of the activity of AMS35AA for metastatic murine melanoma cells (B16F10) in experimental model in vitro and, in pre-clinic assay of metastatic melanoma in vivo, using mice lineage C57BL/6.

MAIN METHODS

In vitro assays were performed: MTT and comet assay, flow cytometry evaluation, gene expression assay by RT-PCR, qualitative evaluation of cell death using B16F10 cells. In vivo assays: micronucleus and comet assay, splenic phagocytosis, melanoma murine model and histopathological analysis, using mice lineage C57BL/6 (n = 20).

KEY FINDINGS

In vitro results performed by MTT assay showed that AMS35AA is cytotoxic for B16F10 cells (p < 0.05). Based on comet assay the genotoxicity of the IC₅₀ was determined (95.83 μg/mL) (p < 0.05). These data were corroborated by flow cytometry analysis after the treatment with AMS35AA, which indicates the cellular death by apoptosis (p < 0.05) and increasing of ATR, p53, p21 and GADD45 gene expressions verified using RT-PCR. With respect to in vivo results, it was observed that AMS35AA did not show genotoxic activity. Data of tumor volume ex vivo indicate reduction of tumor for the treated animals with AMS35AA up to 15.84×, which is superior to Dacarbazina (50 mg/Kg, p.c.; i.p.).

SIGNIFICANCE

In summary, the study showed that AMS35AA reveals relevant results regarding to cytotoxicity of B16F10 murine melanoma cells, inducing death by apoptosis via mitochondrial and/or mediated by DNA damages.

Assessment of genetic integrity, splenic phagocytosis and cell death potential of (Z)-4-((1,5-dimethyl-3-oxo-2-phenyl-2,3dihydro-1H-pyrazol-4-yl) amino)-4-oxobut-2-enoic acid and its effect when combined with commercial chemotherapeutics

The increased incidence of cancer and its high treatment costs have encouraged the search for new compounds to be used in adjuvant therapies for this disease. This study discloses the synthesis of (Z)-4-((1,5-dimethyl-3-oxo-2-phenyl-2,3dihydro-1H-pyrazol-4-yl) amino)-4-oxobut-2-enoic acid (IR-01) and evaluates not only the action of this compound on genetic integrity, increase in splenic phagocytosis and induction of cell death but also its effects in combination with the commercial chemotherapeutic agents doxorubicin, cisplatin and cyclophosphamide. IR-01 was designed and synthesized based on two multifunctionalyzed structural fragments: 4-aminoantipyrine, an active dipyrone metabolite, described as an antioxidant and anti-inflammatory agent; and the pharmacophore fragment 1,4-dioxo-2-butenyl, a cytotoxic agent. The results indicated that IR-01 is an effective chemoprotector because it can prevent clastogenic and/or aneugenic damage, has good potential to prevent genomic damage, can increase splenic phagocytosis and lymphocyte frequency and induces cell death. However, its use as an adjuvant in combination with chemotherapy is discouraged since IR-01 interferes in the effectiveness of the tested chemotherapeutic agents. This is a pioneer study as it demonstrates the chemopreventive effects of IR-01, which may be associated with the higher antioxidant activity of the precursor structure of 4-aminoantipyrine over the effects of the 1,4-dioxo-2-butenyl fragment.

Genetic toxicological assessment and anti-arthritic effects of an ethanolic extract obtained from Salvia lachnostachys Benth leaves in mice

In the present study, mice were subjected to prolonged treatment with ethanolic extract of Salvia lachnostachys Benth leaves (SLEE), and the inflammatory and arthritic parameters were evaluated using the Complete Freund's Adjuvant (CFA) model. The genotoxicity of SLEE were also assayed using genetic toxicological tests. For the CFA model, 28 male C57BL/6 mice were distributed randomly into four groups (control, 50 mg/kg of SLEE, 100 mg/kg of SLEE and dexamethasone) for the evaluation of hyperalgesia and paw edema for 21 days after injection of CFA into the paw. To conduct the toxicogenetic assessments (comet assay and micronuclei assay), apoptosis and splenic phagocytosis were evaluated in male Swiss mice after the administration of saline (control group), cyclophosphamide (positive control group) and SLEE (10, 100 and 1000 mg/kg). SLEE significantly reduced the mechanical hyperalgesia and edema caused by CFA injection. The results of the toxicogenetic assessment revealed no toxicogenetic potential in the mice, and the evaluation of apoptosis showed an increase in apoptotic cells in the spleen after 72 h of treatment with SLEE (1000 mg/kg). SLEE exhibited anti-arthritic activity with no toxicogenetic damage. These toxicogenic results support the safety of SLEE.

Cardanol: toxicogenetic assessment and its effects when combined with cyclophosphamide

Cardanol is an effective antioxidant and is a compound with antimutagenic and antitumoral activity. Here, we evaluated the genotoxic and mutagenic potential of saturated side chain cardanol and its effects in combination with cyclophosphamide in preventing DNA damage, apoptosis, and immunomodulation. Swiss mice were treated with cardanol (2.5, 5 and 10 mg/kg) alone or in combination with cyclophosphamide (100 mg/kg). The results showed that cardanol is an effective chemopreventive compound, with damage reduction percentages that ranged from 18.9 to 31.76% in the comet assay and from 45 to 97% in the micronucleus assay. Moreover, cardanol has the ability to reduce the frequency of apoptosis induced by cyclophosphamide. The compound did not show immunomodulatory activity. A final interpretation of the data showed that, despite its chemoprotective capacity, cardanol has a tendency to induce DNA damage. Hence, caution is needed if this compound is used as a chemopreventive agent. Also, this compound is likely not suitable as an adjuvant in chemotherapy treatments that use cyclophosphamide.