Host plant stimuli effects on survival and duration of dormancy of Rhagoletis zoqui, Rhagoletis completa (Diptera: Tephritidae) and associated parasitoids.

Tephritid fruit flies in the genus Rhagoletis bridge between predictable periods of fruit availability by becoming dormant. To cope with acyclic unpredictable events (e.g., frost, mast seeding, etc), a proportion of the population can undergo prolonged dormancy. In the case of walnut infesting Rhagoletis, host plant-derived cues such as juglone soil concentration vary seasonally in predictable patterns. Here, we examined the effects of host plant parts and derived compounds on emergence rates and dormancy duration of Rhagoletis completa (Cresson), Rhagoletis zoqui (Bush) (Diptera: Tephritidae), and associated parasitoids. Pupae of both species were exposed to walnut leaves, fruit, or fruit and leaves and compared to a control. In a second experiment, R. zoqui were exposed to 10 mg l-1 of juglone applied to pupation medium during four consecutive 4-week time periods under variable combinations of temperature and frequency of exposure. Overall, the presence of fruit resulted in greater overwintering survival of R. completa but had no effect on the duration of dormancy of either fly species. Application of juglone over two consecutive periods produced greater mortality of R. zoqui than the control. Three parasitoid species emerged from R. completa and one from R. zoqui. Duration of dormancy for parasitoids was longer than that of fly hosts. Regardless of treatment, 13.3-18.4% of R. completa pupae and 1.3-2.8% R. zoqui engaged in prolonged (>year) dormancy. Our results indicate that host plant derived cues have little or no effect on survival and duration of dormancy of walnut infesting Rhagoletis, and at the tested concentration juglone is toxic to R. zoqui pupae. Testing the effect of juglone at lower concentrations is necessary to rule out its role as an environmental cue for regulation of dormancy. So far, host plant fruiting phenology appears to play a greater role than host plant derived cues in selecting for fly eclosion times.

Juglone: A Versatile Natural Platform for Obtaining New Bioactive Compounds.

Juglone is a metabolite produced by several species of plants, in particular Juglans nigra. Additionally, juglone is a 1,4-naphthoquinone that has several biological actions. Antimicrobial, antifungal, sedative, oxidizing, antihypertensive, and especially anti-proliferative actions have been described for juglone. This justifies that 1,4-naphthoquinone is a privileged structure for Medicinal Chemistry, and it is useful for the development of new prototypes with varied actions. In this work, we make a profound review of juglone synthesis methodology, the biological actions of juglone, and mainly the synthesis and pharmacological actions of juglone derivatives. We hope that the potent biological actions described for these derivatives in this review will stimulate the continuous design, synthesis, and pharmacological evaluation of new juglone derivatives.

(3,3'-Methylene)bis-2-hydroxy-1,4-naphthoquinones induce cytotoxicity against DU145 and PC3 cancer cells by inhibiting cell viability and promoting cell cycle arrest.

We developed a novel method for the synthesis of bis-naphthoquinones (BNQ), which are hybrids of lawsone (2-hydroxy-1,4-naphthoquinone) and 3-hydroxy-juglone (3,5-dihydroxy-1,4-naphthoquinone). The anticancer activity of three synthesized compounds, named 4 (RC10), 5 (RCDFC), and 6 (RCDOH) was evaluated in vitro against two metastatic prostate cancer (PCa) cell lines, DU145 and PC3, using MTT assays. We found that 4 (RC10) and 5 (RCDFC) induced cytotoxicity against DU145 and PC3 cells. Flow cytometry analysis revealed that these two compounds promoted cell cycle arrest in G1/S and G2/M phases, increased Sub-G1 peak and induced inhibition in cell viability. We also showed that these effects are cell-type context dependent and more selective for these tested PCa cells than for HUVEC non-tumor cells. The two BNQ compounds 4 (RC10) and 5 (RCDFC) displayed promising anticancer activity against the two tested metastatic PCa cell lines, DU145 and PC3. Their effects are mainly associated with inhibition of cell viability, possibly through apoptotic cell death, besides altering the SubG1, G1/S and G2/M phases of cell cycle. 5 (RCDFC) compound was found to be more selective than 4 (RC10), when comparing their cytotoxic effects in relation to HUVEC non-tumoral cells. Future work should also test these compounds in combination with other chemotherapeutic drugs to evaluate their effects on further sensitizing drug-resistant metastatic PCa cells.

Thermal stability data of juglone from extracts of walnut (Juglans regia) green husk, and technologies used to concentrate juglone.

The data presented in this article are focused on thermal stability data of both juglone standard (in ethanol and methanol) and a natural extract containing juglone from lyophilized walnut green husk (in ethanol and methanol). On the other hand, we also show the data of the impact of three concentration technologies over the concentration yield of juglone from the natural extract in ethanol and methanol. All data presented are related with the information included in "Polyphenolic extracts of walnut (Juglans regia) green husk containing juglone inhibit the growth of HL-60 cells and induce apoptosis" Soto-Maldonado et al., 2019, where the discussion and interpretation of results can be found.

Polyphenolic extracts of walnut (Juglans regia) green husk containing juglone inhibit the growth of HL-60 cells and induce apoptosis

BACKGROUND: Juglone is a naphthoquinone currently obtained by chemical synthesis with biological activities including antitumor activity. Additionally, juglone is present in the green husk of walnut, which suggests evaluating the effect of GH extracts on carcinogenic cell lines. RESULTS: Walnut green husk ethanolic extract was obtained as 169.1 mg juglone/100 g Green Husk and antioxidant activity (ORAC) of 44,920 µmol Trolox Equivalent/100 g DW Green Husk. At 1 µM juglone in HL-60 cell culture, green husk extract showed an antiproliferative effect, but pure juglone did not; under these conditions, normal fibroblast cells were not affected. A dose-dependent effect on mitochondrial membrane potential loss was observed. Apoptosis of HL-60 was detected at 10 µM juglone. Despite high ORAC values, neither purified juglone nor the extract showed protective effects on HL-60 cells under oxidative conditions. CONCLUSIONS: Green husk extract generates an antiproliferative effect in HL-60 cells, which is related to an induction of the early stages of apoptosis and a loss of mitochondrial membrane potential. The normal cells were not affected when juglone is present at concentrations of 1 µM, while at higher concentrations, there is loss of viability of both cancerous and healthy cells.

In vivo inhibition of tumor progression by 5 hydroxy-1,4-naphthoquinone (juglone) and 2-(4-hydroxyanilino)-1,4-naphthoquinone (Q7) in combination with ascorbate.

The purpose of the study was to obtain further in vivo data of antitumor effects and mechanisms triggered by juglone and Q7 in combination with ascorbate. The study was done using Ehrlich ascites tumor-bearing mice. Treatments were intraperitoneal every 24 h for 9 days. Control group was treated with excipient. Previous tests selected the doses of juglone and Q7 plus ascorbate (1 and 100 mg/kg, respectively). Samples of ascitic fluid were collected to evaluate carbonyl proteins, GSH and activity of antioxidant enzymes such as catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase. Hypoxia inducible factor HIF-1α, GLUT1, proteins driving cell cycle (p53, p16 and cyclin A) and apoptosis (poly-ADP-polymerase PARP, Bax and Bcl-xL) were assessed by western blot. Tumor cells were categorized by the phase of cell cycle using flow cytometry and type of cell death using acridine orange/ethidium bromide. A glucose uptake assessment was performed by liquid scintillation using Ehrlich tumor cells cultured with (14)C-deoxyglucose. Treatments caused increased protein carbonylation and activity of antioxidant enzymes and decreased levels of GSH, HIF-1α, GLUT1 and glucose uptake in tumor cells. They also caused increased number of tumor cells in G1, p53 and p16 activation and decreased cyclin A, but only when combined with ascorbate. Apoptosis was induced mostly when treatments were done with ascorbate, causing PARP and Bax cleavage, and increased Bax/Bcl-xL ratio. Juglone and Q7 in combination with ascorbate caused inhibition of tumor progress in vivo by triggering apoptosis and cell cycle arrest associated with oxidative stress, suppression of HIF-1 and uncoupling of glycolytic metabolism.

Protective effects of novel organic selenium compounds against oxidative stress in the nematode Caenorhabditis elegans.

Organic selenium compounds possess numerous biological properties, including antioxidant activity. Yet, the high toxicity of some of them, such as diphenyl diselenide (DPDS), is a limiting factor in their current usage. Accordingly, we tested four novel organic selenium compounds in the non-parasite nematode Caenorhabditis elegans and compared their efficacy to DPDS. The novel organic selenium compounds are ß-selenoamines (1-phenyl-3-(p-tolylselanyl)propan-2-amine (C1) and 1-(2-methoxyphenylselanyl)-3-phenylpropan-2-amine (C2) and analogs of DPDS (1,2-bis (2-methoxyphenyl) diselenide (C3) and 1,2-bisp-tolyldiselenide (C4). Synchronized worms at the L4 larval stage were exposed for one hour in M9 buffer to these compounds. Oxidative stress conditions were induced by juglone (200 µM) and heat shock (35 °C). Moreover, we evaluated Caenorhabditis elegans behavior, GST-4::GFP (glutathione S-transferase) expression and the activity of acetylcholinesterase (AChE). All tested compounds efficiently restored viability in juglone stressed worms. However, DPDS, C2, C3 and C4 significantly decreased the defecation cycle time. Juglone-induced GST-4::GFP expression was not attenuated in worms pretreated with the novel compounds, except with C2. Finally, AChE activity was reduced by DPDS, C2, C3 and C4. To our knowledge, this is study firstly showed the effects of C1, C2, C3 and C4 selenium-derived compounds in Caenorhabditis elegans. Low toxic effects were noted, except for reduction in the defecation cycle, which is likely associated with AChE inhibition. The juglone-induced stress (reduced viability) was fully reversed by compounds to control animal levels. C2 was also efficient in reducing the juglone-induced GST-4::GFP expression, suggesting the latter may mediate the stress induced by this compound. Future studies could be profitably directed at addressing additional molecular mechanisms that mediate the protective effects of these novel organic selenium compounds.