The impact of green tea polyphenols on development and reproduction in Drosophila melanogaster

Co-administration of resveratrol rescued lead-induced toxicity in Drosophila melanogaster

Lead toxicity poses a significant environmental concern linked to diverse health issues. This study explores the potential mitigating effects of resveratrol on lead-induced toxicity in Drosophila melanogaster. Adult fruit flies, aged three days, were orally exposed to lead (60 mg/L), Succimer (10 mg), and varying concentrations of resveratrol (50, 100, and 150 mg). The investigation encompassed the assessment of selected biological parameters, biochemical markers, oxidative stress indicators, and antioxidant enzymes. Resveratrol exhibited a dose-dependent enhancement of egg-laying, eclosion rate, filial generation output, locomotor activity, and life span in D. melanogaster, significantly to 150 mg of diet. Most of the investigated biochemical parameters were significantly rescued in lead-exposed fruit flies when co-treated with resveratrol (p < 0.05). However, oxidative stress remained unaffected by resveratrol. The findings suggest that resveratrol effectively protects against lead toxicity in Drosophila melanogaster and may hold therapeutic potential as an agent for managing lead poisoning in humans.

The plant specialized metabolite epicatechin- 3-gallate (EC3G) perturbs lipid metabolism and attenuates fat accumulation in pigeonpea pod borer, Helicoverpa armigera

Control of pod borer Helicoverpa armigera, a notorious polyphagous pest requires paramount attention with focus on environment-friendly management approaches. Overproduction of catechins (epigallocatechin-EGC and epicatechin-3-gallate-EC3G) in the pod borer-resistant pigeonpea wild relative, Cajanus platycarpus during continued herbivory prodded us to assess their underlying molecular effect on H. armigera. Significant reduction in larval and pupal growth parameters was observed when reared on artificial diet incorporated with 100 ppm EC3G vis a vis 100 ppm EGC and EGC + EC3G. Comparative RNAseq analyses of larvae that fed on normal and EC3G-incorporated diet revealed 62 differentially expressed genes dominated by detoxification and lipid metabolism. While lipase and fatty acid-binding protein 2-like were up-regulated, delta9-FADS-like involved in fatty acid synthesis was downregulated, indicating effect of EC3G on fat metabolism. Validation of RNAseq data by qPCR; midgut glutathione-S-transferase and esterase assays depicted increased lipolysis and reduced lipogenesis in EC3G-fed larvae. Additionally, differential accumulation of stearic acid and oleic acid in EC3G-fed and control larvae/adults ascertained perturbation in lipogenesis. Supported by modelling, molecular docking and simulations, we demonstrate the possible involvement of the insect adipokinetic hormone receptor (AKHR) in the EC3G-mediated response. The study demonstrates plant specialized metabolite EC3G as a potential candidate for H. armigera control.

Characteristics of Leaf Spot Disease Caused by Didymella Species and the Influence of Infection on Tea Quality

Leaf spots are the most damaging and common foliar diseases of tea and are caused by several species of fungi. During 2018 to 2020, leaf spot diseases showing different symptoms (large and small spots) were observed in commercial tea plantations in Guizhou and Sichuan provinces of China. The pathogen causing the two different sized leaf spots was identified as the same species (Didymella segeticola) based on morphological characteristics, pathogenicity, and multilocus phylogenetic analysis using the combined ITS, TUB, LSU, and RPB2 gene regions. Microbial diversity analysis of lesion tissues from small spots on naturally infected tea leaves further confirmed Didymella to be present as the main pathogen. Results of sensory evaluation and quality-related metabolite analysis of tea shoots infected with the small leaf spot symptom indicated that D. segeticola negatively affected the quality and flavor of tea by changing the composition and content of caffeine, catechins, and amino acids. In addition, the significantly reduced amino acid derivatives in tea are confirmed to be positively associated with the enhanced bitter taste. The results improve our understanding of the pathogenicity of Didymella species and the influence of Didymella on the host plant, Camellia sinensis.

Apple Polyphenol Diet Extends Lifespan, Slows down Mitotic Rate and Reduces Morphometric Parameters in Drosophila Melanogaster: A Comparison between Three Different Apple Cultivars

Plant-derived polyphenols exhibit beneficial effects on physiological and pathological processes, including cancer and neurodegenerative disorders, mainly because of their antioxidant activity. Apples are highly enriched in these compounds, mainly in their peel. The Tuscia Red (TR) apple variety exhibits the peculiar characteristic of depositing high quantities of polyphenols in the pulp, the edible part of the fruit. Since polyphenols, as any natural product, cannot be considered a panacea per se, in this paper, we propose to assess the biological effects of TR flesh extracts, in comparison with two commercial varieties, in a model system, the insect Drosophila melanogaster, largely recognized as a reliable system to test the in vivo effects of natural and synthetic compounds. We performed a comparative, qualitative and quantitative analysis of the polyphenol compositions of the three cultivars and found that TR flesh shows the highest content of polyphenols, and markedly, anthocyanins. Then, we focused on their effects on a panel of physiological, morphometrical, cellular and behavioral phenotypes in wild-type D. melanogaster. We found that all the apple polyphenol extracts showed dose-dependent effects on most of the phenotypes we considered. Remarkably, all the varieties induced a strong relenting of the cell division rate.

Ameliorative effect of bayberry leaves proanthocyanidins on high sugar diet induced Drosophila melanogaster

Bayberry leaves proanthocyanidins (BLPs) were distributed in natural plant food, considered to have the potential for metabolic syndrome. In this study, we raised Drosophila melanogaster on high sugar diet (HSD) from the egg stage to induce hyperglycemia, and the ameliorative effect of BLPs was assessed based on this model. Phenotypical, biochemical, and molecular analyses related to diabetes mellitus pathogenesis were measured. Flies exposed to BLPs were found to suppress the HSD-induced high glucose and high triglycerides levels. Moreover, BLPs showed an inhibitory effect on carbohydrate digestive enzymes (α-amylase and α-glucosidase) activity and mRNA expression, exhibiting the potential for carbohydrate digestion retardation. Transcriptional levels of key genes associated with glycolipid metabolism were further evaluated, including dilp, InR, and downstream dAKT-dFOXO-PEPCK, together with E78, SREBP, FAS, and LSD genes, were all downregulated after BLPs-exposure, suggesting the ameliorative effect of BLPs on dysbiosis associated with the insulin signaling pathway. This study provided a new functional compound, which is beneficial to further antidiabetic therapy studies.

(+)-Catechin, epicatechin and epigallocatechin gallate are important inducible defensive compounds against Ectropis grisescens in tea plants

The tea plant, Camellia sinensis (L.) O. Kuntze, is an economically important, perennial woody plant rich in catechins. Although catechins have been reported to play an important role in plant defences against microbes, their roles in the defence of tea plants against herbivores remain unknown. In this study, we allowed the larvae of Ectropis grisescens, a leaf-feeding pest, to feed on the plants, and alternatively, we wounded the plants and then treated them with E. grisescens oral secretions (WOS). Both approaches triggered jasmonic acid-, ethylene- and auxin-mediated signalling pathways; as a result, plants accumulated three catechin compounds: (+)-catechin, epicatechin and epigallocatechin. Not only was the mass of E. grisescens larvae fed on plants previously infested with E. grisescens or treated with WOS significantly lower than that of larvae fed on controls, but also artificial diet supplemented with epicatechin, (+)-catechin or epigallocatechin gallate reduced larval growth rates. In addition, the exogenous application of jasmonic acid, ethylene or auxin induced the biosynthesis of the three catechins, which, in turn, enhanced the resistance of tea plants to E. grisescens, leading to the coordination of the three signalling pathways. Our results suggest that the three catechins play an important role in the defences of tea plants against E. grisescens.

Potential of Cucurbitacin B and Epigallocatechin Gallate as Biopesticides against Aphis gossypii

Simple Summary

The Aphis gossypii is a global problem for its pesticide resistance with substantial economic and ecological cost and a wide host range, including cotton and cucurbits. The development of insecticide resistance is rapid and widespread and threatens crop productivity. Biopesticides have emerged as a better alternative for pest control. Cucurbitacin B (CucB) and epigallocatechin gallate (EGCG) are the major secondary metabolites of host plants cucurbits and cotton. In this study, we used cotton- and cucurbit-specialized aphids (CO and CU) as a study system to better understand the effects of CucB and EGCG on cotton aphid. Our study showed that CucB and EGCG can significantly reduce the population-level fitness of A. gossypii, affect their ability to adapt to nonhost plants and alter the levels of some detoxifying enzymes, which showed a potential to be developed into new biopesticides against the notorious aphids.

Abstract

Aphis gossypii (Glover) is distributed worldwide and causes substantial economic and ecological problems owing to its rapid reproduction and high pesticide resistance. Plant-derived cucurbitacin B (CucB) and epigallocatechin gallate (EGCG) are known to have insecticidal and repellent activities. However, their insecticidal activity on cotton- and cucurbit-specialized aphids (CO and CU), the two important host biotypes of A. gossypii, remains to be investigated. In the present study, we characterized, for the first time, the effects of these two plant extracts on the two host biotypes of A. gossypii. CucB and EGCG significantly reduced the A. gossypii population-level fitness and affected their ability to adapt to nonhost plants. Activities of important detoxification enzymes were also altered, indicating that pesticide resistance is weakened in the tested aphids. Our results suggest that CucB and EGCG have unique properties and may be developed as potential biopesticides for aphid control in agriculture.

The Drosophila Model: Exploring Novel Therapeutic Compounds against Neurodegenerative Diseases

Polyphenols are secondary metabolites of plants, fruits, and vegetables. They act as antioxidants against free radicals from UV light, pathogens, parasites, and oxidative stress. In Drosophila models, feeding with various polyphenols results in increased antioxidant capacity and prolonged lifespan. Therefore, dietary polyphenols have several health advantages for preventing many human diseases, including cardiovascular diseases, cancer, and neurodegenerative diseases. However, the exact role of polyphenols in neurodegenerative diseases is still yet to be completely defined. This review focuses on the most recent studies related to the therapeutic effect of polyphenols in neurodegenerative disease management and provides an overview of novel drug discovery from various polyphenols using the Drosophila model.

Acute and Subchronic Oral Toxicity of Fermented Green Tea with Aquilariae Lignum in Rodents

Green tea is generally considered safe, but there have been concerns regarding side effects relating to the main component, catechins, especially hepatotoxicities. We have previously shown beneficial effects of fermented green tea with Aquilariae Lignum (fGT) via an oral route in diabetic and obese models. Thus, the toxicological safety of fGT was assessed at limited oral doses for a rodent. Mice or rats of both genders were orally administered distilled water as a control and fGT at 2.0, 1.0, and 0.5 g/kg. There were no mortalities or gross abnormalities in the fGT groups for 2 weeks following the single oral dose in mice. No fGT-relevant abnormalities were found in postmortem and histopathological examinations, suggesting LD₅₀ of fGT at more than 2.0 g/kg with no specific target organs. There were also no fGT-relevant mortalities or abnormal signs in the repeated oral dose for 13 weeks in rats. In the fGT groups, no body weight changes or daily metabolic changes were found, and hematological and serum biochemical ranges were normal. The postmortem and histopathological examinations revealed few fGT-related abnormalities in most of the organs including the liver, although slight lymphoid cell hyperplasia in the lymph node was observed in a few rats with fGT at 2.0 g/kg. This may be secondary to increased immune response to the highest dose because there were no histopathological lesions or organ weight changes. It suggests nontoxic safety of fGT at up to 2.0 g/kg, which provides useful information for clinical use.

Impact of probiotics on development and behaviour in Drosophila melanogaster - a potential in vivo model to assess probiotics

In vitro models are frequently used in probiotic research. However, such models often fail to predict in vivo functionality and efficacy. This fact complicates the screening process for selecting the most suitable strains, prior to accomplish expensive animal studies and clinical intervention trials. Therefore, additional sensitive, discriminating and cost-effective models are needed to conduct preliminary assays before undertaking human intervention studies definitely proving efficacy. With this purpose in mind, we explored the potential of axenic Drosophila melanogaster populations as well as of these axenic flies treated with probiotic microbial strains as a model to test the effects of probiotics on a subset of developmental and behavioural traits. An axenic D. melanogaster progeny from the wild-type Canton S strain was obtained and its eggs were further developed until pupae eclosion occurred in growth medium containing either of two probiotic strains: Bifidobacterium animalis subsp. lactis Bb12 or Lactobacillus rhamnosus GG. Whereas B. animalis Bb12 colonised the flies, the capacity of L. rhamnosus LGG to colonise was considerably lower in our experimental conditions. Regarding the influence of microbial load on the flies' development, the axenic condition caused a decrease in egg survival, and lowered adults' average weight with respect to wild-type flies. Both probiotics were able to counteract these effects. An earlier emergence of adults was observed from eggs treated with L. rhamnosus GG in comparison to the other fly populations. The axenic condition did not influence negative geotaxis behaviour in Drosophila; however, flies mono-associated with B. animalis Bb12 moved faster than wild-type. Our results suggest that the use of axenic/probiotic-treated D. melanogaster populations may be an affordable model for preliminary testing of the effects of probiotics on developmental or behavioural aspects.

Toxicological effects of Camellia sinensis (green tea): A review

Many scientific articles proved that green tea (GT), Camellia sinensis, has a great potential to manage central nervous system, cardiovascular, and metabolic diseases and treat cancer and inflammatory disorders. However, it is important to consider that "natural" is not always "safe." Some relevant articles reported side effects of GT, detrimental effects on health. The aim of this study is to provide a classified report about the toxicity of GT and its main constituents in acute, subacute, subchronic, and chronic states. Furthermore, it discusses on the cytotoxicity, genotoxicity, mutagenicity, carcinogenicity, and developmental toxicity of GT and its main constituents. The most important side effects have been reported hepatotoxicity and gastrointestinal disorders specially while consumed on an empty stomach. GT and its main components are not major teratogen, mutagen, or carcinogen substances. However, there is limited data in using them during pregnancy, and they should be used with caution in pregnancy, breast-feeding, and susceptible people. Because GT and its main components have a wide variety of drug interactions, consideration should be taken in coadministration of them with narrow therapeutic indexed drugs. Furthermore, they evoke selective cytotoxicity on cancerous cells that could engage them as an adjuvant substance in cancer therapy.

Drosophila melanogaster "a potential model organism" for identification of pharmacological properties of plants/plant-derived components

Plants/plant-derived components have been used from ancient times to treat/cure several human diseases. Plants and their parts possess several chemical components that play the vital role in the improvement of human health and their life expectancy. Allopathic medicines have been playing a key role in the treatment of several diseases. Though allopathic medicines provide fast relief, long time consumption cause serious health concerns such as hyperallergic reactions, liver damage, etc. So, the study of medicinal plants which rarely cause any side effect is very important to mankind. Plants contain many health benefit properties like antioxidant, anti-aging, neuroprotective, anti-genotoxic, anti-mutagenic and bioinsecticidal activity. Thus, identification of pharmacological properties of plants/plant-derived components are of utmost importance to be explored. Several model organisms have been used to identify the pharmacological properties of the different plants or active components therein and Drosophila is one of them. Drosophila melanogaster "fruit fly" is a well understood, high-throughput model organism being used more than 110 years to study the different biological aspects related to the development and diseases. Most of the developmental and cell signaling pathways and ∼75% human disease-related genes are conserved between human and Drosophila. Using Drosophila, one can easily analyze the pharmacological properties of plants/plant-derived components by performing several assays available with flies such as survivorship, locomotor, antioxidant, cell death, etc. The current review focuses on the potential of Drosophila melanogaster for the identification of medicinal/pharmacological properties associated with plants/plant-derived components.

Green tea proanthocyanidins cause impairment of hormone-regulated larval development and reproductive fitness via repression of juvenile hormone acid methyltransferase, insulin-like peptide and cytochrome P450 genes in Anopheles gambiae sensu stricto

Successful optimization of plant-derived compounds into control of nuisance insects would benefit from scientifically validated targets. However, the close association between the genotypic responses and physiological toxicity effects mediated by these compounds remains underexplored. In this study, we evaluated the sublethal dose effects of proanthocyanidins (PAs) sourced from green tea (Camellia sinensis) on life history traits of Anopheles gambiae (sensu stricto) mosquitoes with an aim to unravel the probable molecular targets. Based on the induced phenotypic effects, genes selected for study targeted juvenile hormone (JH) biosynthesis, signal transduction, oxidative stress response and xenobiotic detoxification in addition to vitellogenesis in females. Our findings suggest that chronic exposure of larval stages (L3/L4) to sublethal dose of 5 ppm dramatically extended larval developmental period for up to 12 days, slowed down pupation rates, induced abnormal larval-pupal intermediates and caused 100% inhibition of adult emergence. Further, females exhibited significant interference of fecundity and egg hatchability relative to controls (p < 0.001). Using reverse transcription quantitative polymerase chain reaction (RT-qPCR), our findings show that PA-treated larvae exhibited significant repression of AgamJHAMT (p < 0.001), AgamILP1 (p < 0.001) and AgamCYP6M2 (p < 0.001) with up-regulation of Hsp70 (p < 0.001). Females exposed as larvae demonstrated down-regulation of AgamVg (p = 0.03), AgamILP1 (p = 0.009), AgamCYP6M2 (p = 0.05) and AgamJHAMT (p = 0.02). Our findings support that C. sinensis proanthocyanidins affect important vectorial capacity components such as mosquito survival rates and reproductive fitness thus could be potentially used for controlling populations of malaria vectors.

Influence of Quercetin in the Temporal Regulation of Redox Homeostasis in Drosophila melanogaster

Numerous biological processes are governed by the biological clock. Studies using Drosophila melanogaster (L.) are valuable that could be of importance for their effective applications on rodent studies. In this study, the beneficial role of quercetin (a flavonoid) on H2O2 induced stress in D. melanogaster was investigated. D. melanogaster flies were divided into four groups (group I - control, group II - H2O2 (acute exposure), group III - quercetin, and group IV - quercetin + H2O2 treated). Negative geotaxis assay, oxidative stress indicators (protein carbonyls, thiobarbituric reactive substances [TBARS]), and antioxidants (superoxide dismutase [SOD], catalase [CAT], glutathione-S-transferase [GST], glutathione peroxidase, and reduced glutathione [GSH]) were measured at 4 h intervals over 24 h and temporal expression of heat shock protein-70 (Hsp70), Upd1 (homolog of IL-6 in Drosophila), and nitric oxide synthase (Nos) was analyzed by Western blotting. Groups II and IV showed altered biochemical rhythms (compared with controls). Decreased mesor values of negative geotaxis, SOD, CAT, GST, and GSH were noticed in H2O2, increased mesor of oxidative stress indicators (TBARS and protein carbonyl content) and a reversibility of the rhythmic characteristics were conspicuous after quercetin treatment. The expression levels of Hsp70, Upd1, and Nos were noticeably maximum at 04:00. Significant elevation of expression by H2O2 was nearly normalized by quercetin treatment. The possible mechanism by which quercetin modulates oxidant-antioxidant imbalance under oxidative stress could be ascribed to the modulation of the rhythmic properties. Our results will be helpful to understand the molecular interlink between circadian rhythm and oxidative stress mechanism.

Green tea polyphenols require the mitochondrial iron transporter, mitoferrin, for lifespan extension in Drosophila melanogaster

Green tea has been found to increase the lifespan of various experimental animal models including the fruit fly, Drosophila melanogaster. High in polyphenolic content, green tea has been shown to reduce oxidative stress in part by its ability to bind free iron, a micronutrient that is both essential for and toxic to all living organisms. Due to green tea's iron-binding properties, we questioned whether green tea acts to increase the lifespan of the fruit fly by modulating iron regulators, specifically, mitoferrin, a mitochondrial iron transporter, and transferrin, found in the hemolymph of flies. Publicly available hypomorph mutants for these iron regulators were utilized to investigate the effect of green tea on lifespan and fertility. We identified that green tea could not increase the lifespan of mitoferrin mutants but did rescue the reduced male fertility phenotype. The effect of green tea on transferrin mutant lifespan and fertility were comparable to w¹¹¹⁸ flies, as observed in our previous studies, in which green tea increased male fly lifespan and reduced male fertility. Expression levels in both w¹¹¹⁸ flies and mutant flies, supplemented with green tea, showed an upregulation of mitoferrin but not transferrin. Total body and mitochondrial iron levels were significantly reduced by green tea supplementation in w¹¹¹⁸ and mitoferrin mutants but not transferrin mutant flies. Our results demonstrate that green tea may act to increase the lifespan of Drosophila in part by the regulation of mitoferrin and reduction of mitochondrial iron.

Potential of Camellia sinensis proanthocyanidins-rich fraction for controlling malaria mosquito populations through disruption of larval development

BACKGROUND

Anopheles arabiensis and A. gambiae (sensu stricto) are the most prolific Afrotropical malaria vectors. Population control efforts of these two vectors have been hampered by extremely diverse larval breeding sites and widespread resistance to currently available insecticides. Control of mosquito larval stages using bioactive compounds of plant origin has the potential to suppress vector populations leading to concomitant reduction in disease transmission rates. In this study, we evaluated the efficacy of Camellia sinensis crude leaf extract and its fraction against the larvae of A. arabiensis and A. gambiae (s.s.).

METHODS

Late third/early fourth instar larvae (L3/L4) of A. arabiensis and A. gambiae (s.s.) were exposed to increasing doses of C. sinensis leaf extract and its active fraction for 72 h, with mortality rates recorded every 24 h in both control and test groups. Ultra performance liquid chromatography electron spray ionization quadruple time of flight coupled with mass spectrometry (UPLC/ESI-Qtof/MS) was used to determine the main active constituents in the fraction.

RESULTS

The major bioactive chemical constituents in the C. sinensis leaf extract were identified to be proanthocyanidins. The extract significantly interfered with larval survival and adult emergence in both species (ANOVA, F _(5,24) = 1435.92, P < 0.001). Additionally, larval exposure to crude extract at 250 ppm and 500 ppm for 24 h resulted in larval mortality rates of over 90 % in A. gambiae (s.s.) and 75 % in A. arabiensis. A relatively lower concentration of 100 ppm resulted in moderate mortality rates of < 50 % in both species, but induced growth disruption effects evident as abnormal larval-pupal intermediates and disrupted adult emergence. The estimated LC₅₀ concentrations of the crude leaf extract against A. arabiensis and A. gambiae (s.s.) larvae at 24 h were 154.58 ppm (95 % CI: 152.37-158.22) and 117.15 ppm (95 % CI: 112.86-127.04), respectively. The bioactive polar fraction caused 100 % larval mortality in both vector species at 25 ppm.

CONCLUSIONS

Our findings demonstrate the potential of green tea extract and its active constituents in disrupting mosquito larval development. This could contribute to the control of mosquito populations and improved management of malaria.

Safety and anti-hyperglycemic efficacy of various tea types in mice

Tea, a beverage consumed worldwide, has proven anti-hyperglycemic effects in animal models. Better efficacies of tea beverages are frequently associated with high-dose levels, whose safety attracts considerable attention. Based on the inherent nature of tea catechin oxidation, fresh tea leaves are manufactured into diverse tea types by modulating the oxidation degree of catechins. The present study aimed to assess various tea types for their safety properties and anti-hyperglycemic effects. Mice were allowed free access to tea infusion (1:30, w/v) for one week, and the rare smoked tea caused salient adverse reactions, including hepatic and gastrointestinal toxicities; meanwhile, the widely-consumed green and black teas, unlike the rare yellow tea, suppressed growth in fast-growing healthy mice. When mice were fed a high-fat diet and allowed free access to tea infusion (1:30, w/v) for 25 days, only yellow tea significantly reduced blood glucose. Therefore, various teas showed different safety profiles as well as anti-hyperglycemic efficacy strengths. To achieve an effective and safe anti-hyperglycemic outcome, yellow tea, which effectively suppressed high-fat diet-induced early elevation of hepatic thioredoxin-interacting protein, is an optimal choice.