Aqueous Extract Of Psidium Guajava Research Articles

Phytochemicals and Antibiotic Studies of Ethanolic Extracts of Dennettia Tripetala (Mmimi/Pepper Fruit) and Psidium Guajava (Guava) Leaves on Clinical Isolates of Staphylococcus Aureus and Escherichia Coli

Aqueous and ethanolic leaf extracts of Dennetia tripetala and Psidium guajava were evaluated for their antimicrobial effects against clinical isolates of Staphylococcus aureus and Escherichia coli from Annunciation Specialist Hospital Enugu State Nigeria. The identified isolates were sub-cultured on sterile nutrient agar plates and incubated over night at 37°C. The identified isolates were then re-identified and characterized. Polymerase chain reaction (PCR) was used to detect Staphylococcus aureus strain which has 85% pairwise similarity with Staphylococcus haemolyticus strain SH1 and Escherichia coli strain which has 99.62% pairwise similarity with E. coli strain AC1. Quantitative and qualitative phytochemical analysis were done on the extracts of Dennetia tripetala and Psidium guajava using water and ethanol as extracting solvents. The phytochemical screening of the extracts revealed the presence of tannins, saponins, alkaloids, flavonoids, glycosides and phenols. Quinonas however, was absent in this study. The isolates were screened for sensitivity to different extracts using agar well diffusion technique. The results indicated that both the ethanol and aqueous extracts of the Psidium guajava leaves showed inhibitory activity against Staphylococcus aureus at 10mm and 12mm respectively but no activity against E. coli. On the other hand, the aqueous extracts of the Dennetia tripetala showed inhibitory activity against S. aureus and E. coli at 20mm and 10mm respectively whereas, the ethanol extract has no activity on both test microorganism. The extracts were reconstituted with Dimethyl sulfoxide (DMSO) to concentrations (mg/ml) of 200, 100, 50, 25, 12.5 and the minimal inhibitory concentration (MIC) of the extracts were determined using agar well method. The MIC of the Psidium guajava leaves extract revealed that both ethanolic and aqueous extracts inhibited S. aureus at 12.5mg/ml. While MIC of the Dennetia tripetala revealed that the aquous extract inhibited S. aureus at 50mg/ml and E. coli at 100mg/ml from the results, the aqueous extracts of both plants generally have a better inhibitory property than the ethanolic extracts. Based on the present findings, Dennetia tripetala and Psidium guajava leaves possess the capability of being good candidates in the search for a natural antimicrobial agent against infections or diseases caused by Staphylococcus aureus and Escherichia coli.

Evaluation of the Effect of an Aqueous Extract of Psidium guajava (Guava) Leaves on the Frontal Cortex of Diabetic Wistar Rats

Evaluation of the Effect of an Aqueous Extract of Psidium guajava (Guava) Leaves on the Frontal Cortex of Diabetic Wistar Rats

Efficient removal of Sb(III) from wastewater using selenium nanoparticles synthesized by Psidium guajava plant extract.

Antimony (Sb) pollution in aquatic ecosystems has emerged as a critical environmental issue on a global scale, emphasizing the urgent need for cost-effective and user-friendly technologies to remove Sb compounds from water sources. In this study, a novel adsorbent, selenium nanoparticles (SeNPs), was synthesized using the aqueous extract of Psidium guajava L. leaves (AEP) for the purpose of eliminating Sb(III) from aqueous solutions. The biosynthesized SeNPs was characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray fluorescence spectrometer (XRF), Fourier Transform-Infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis techniques. Additionally, the removal efficiency of the SeNPs for Sb(III) was systematic investigated under the effects of SeNPs dose, temperature, pH and re-usability. The results of this study showed that the adsorption data fitted well into pseudo-second order model, while the Sips modeling demonstrated a high adsorption capacity (62.7mg/g) of SeNPs for Sb(III) ions at 303.15K from aqueous solution. The exothermic enthalpy change of - 22.59kJ/mol and negative Gibbs free energy change assured the viability of the adsorption process under the considered temperature conditions. Surface functional groups on SeNPs like carboxyl, amide, hydroxyl, carbonyl, and methylene significantly facilitate the adsorption processes. Furthermore, the removal efficiencies of Sb in the two actual Sb mine wastewater samples were remarkably high, achieving nearly to 100% with 1.5g/L SeNPs within 48h. This outcome underscores the potential of SeNPs as a highly promising solution for efficiently remediating Sb from aquatic environments, owing to their cost-effectiveness, ease of regeneration, and rapid uptake capabilities.

Efficient reduction of Cr(VI) by guava (Psidium guajava) leaf extract and its mitigation effect on Cr toxicity in rice seedlings

Hexavalent chromium (Cr(VI)) is a toxic element that has negative impacts on crop growth and yield. Using plant extracts to convert toxic Cr(VI) into less toxic Cr(III) may be a more favorable option compared to chemical reducing agents. In this study, the potential effects and mechanisms of using an aqueous extract of Psidium guajava L. leaves (AEP) in reducing Cr(VI) toxicity in rice were comprehensively studied. Firstly, the reducing power of AEP for Cr(VI) was confirmed by the cyclic voltammetry combined with X-ray photoelectron spectroscopy (XPS) assays. The highest Cr(VI) reduction efficiency reached approximately 78% under 1.5 mg gallic acid equivalent (GAE)/mL of AEP and 10 mg/L Cr(VI) condition. Additionally, Cr(VI) stress had a significant inhibitory effect on rice growth. However, the exogenous application of AEP alleviated the growth inhibition and oxidative damage of rice under Cr(VI) stress by increasing the activity and level of enzymatic and non-enzymatic antioxidants. Furthermore, the addition of AEP restored the ultrastructure of root cells, promoted Cr adsorption onto root cell walls, and limited the translocation Cr to shoots. In shoots, AEP application also triggered the expression of specific genes involved in Cr defense and detoxification response, including photosynthesis pathways, antioxidant systems, flavonoids biosynthesis, and plant hormone signal transduction. These results suggest that AEP is an efficient reduction agent for Cr(VI), and exogenous application of AEP may be a promising strategy to mitigate the harm of Cr(VI) on rice, ultimately contributing to improved crop yield in Cr-contaminated environments.

Wormlike reverse micelles loaded with aqueous extracts of Psidium guajava leaves: Performance evaluation by rheology and Raman microscopy methods

Phenolic compounds are molecules that provide health benefits. However, they present problems for their use. The use of wormlike reverse micelles to load aqueous extracts of Psidium guajava (guava) was carried out. Different solutions (i.e., content variation of canola oil, oleic acid, soy lecithin; stirring time, stirring speed) were obtained by incorporation of water by ultrasound and centrifugation. The behavior of the wormlike micelles was evaluated with optical microscopy, simple shear tests, and Raman microscopy with and without aqueous extract of guava leaves. The wormlike reverse micelles solution were adjusted to the Carreau-Yasuda model. Influence of the aqueous extracts of guava leaves were observed in the parameters of Carreau-Yasuda model, related with changes in the packing of the hydroxyl groups and high order of packing in wormlike reverse micellar system.

HYPOGLYCEMIC EFFECT OF PSIDIUM GUAJAVA AND AZADIRACHTA INDICA LEAVES POWDER EXTRACT IN ALLOXAN INDUCED MICE

Traditional plant treatment for Diabetes has shown a surging treatment in the last few decades. This study focuses on herbal Anti Diabetic formulations of two different plants and also mixed group is used in the Treatment of Diabetes. The Efficacy of the herbal plant aqueous extract of Psidium guajava , Azadirachta indica and mixed group (equal amount of Psidium guajava and Azadirachta indica) has been tested on Alloxan induced Diabetic Mice. Three extract fed mice groups were compared to the diabetic mice, for the Hypoglycemic effect. The aqueous plant extract of Psidium guajava dose level of 200 mg/kg body weight , produced a significant decrease in the blood glucose level, when compared to the other two groups. KEY WORDS: Diabetic mellitus, Plant Extract, Alternative medicine, Glucometer.

Influence of factors and interactions in ultrasound-assisted extraction and conventional maceration on aqueous extract of Psidium guajava leaves

Background: Extraction techniques of phenolic compounds (PC), such as conventional maceration (CM) has been associated with high consumption of organic solvents and time. Objective: The objective of this study was to evaluate the effects and interactions of the variables involved in the aqueous extraction of phenolic compounds from Psidium guajava leaves by CM and ultrasound-assisted extraction (UAE). Methods: A split-plot design was developed according to the extraction variables of interest. For CM was time, temperature, and dilution were considered and for UAE the wave amplitude was included. Response variables were considered the following parameters: yield, total phenolic compounds, total flavonoid compounds, antioxidant capacity measured as radical uptake by ABTS and DPPH.Results: The results show that for UAE, the treatment of 1 g/ 50 mL, 50ºC temperature, 30% amplitude, and 20 min of extraction was associated with a higher extraction yield, reporting 125.84 mg of acid gallic equivalents/ g for PC, 381.18 mg quercetin equivalents/g for total flavonoids and 85.28% ABTS and DPPH 40.2% expressed as radical scavenging activity. On the other hand, the maceration method reported best extraction yield, using the treatment of 1 g/ 50 mL of dilution, 50ºC temperature and 10h of extraction time, achieving a total of 62.04 mg of gallic equivalents/ g for PC, 289 mg quercetin equivalents/g for total flavonoids, and 95.9% ABTS and DPPH 48% regarding radical scavenging activity.Conclusion: The ultrasound process was more effective in extracting phenolic compounds, flavonoid compounds, and their extracts had the highest antioxidant capacity. Keywords: Psidium guajava, phenolic compounds, extraction, ultrasound.

Anti-diabetic potential of Psidium guajava leaf in streptozotocin induced diabetic rats

BackgroundPsidium guajava is a medicinal plant with antidiabetic properties and can be found growing in tropical and sub-tropical countries around the world. PurposeThe aim of the present study was to investigate the anti-diabetic potential of Psidium guajava leaf in streptozotocin-induced diabetic rats, with particular focus on key enzymes of glycogen metabolism in skeletal muscle. Study designThe study design involved preparation of an aqueous Psidium guajava leaf extract; investigation of its effect on muscle glycogen synthase and phosphorylase activities and possible protective effect on pancreas in streptozotocin induced diabetic male Sprague-Dawley rats and phytochemical study of the extract to identify further compounds with anti-diabetic potential. MethodDiabetes was induced in male Sprague-Dawley rats with a single intraperitoneal injection of 40 mg/kg streptozotocin. Normal and diabetic animals were treated with 400 mg/kg body weight of Psidium guajava leaves aqueous extract for a period of 14 days. ResultsThe treatment of diabetic animals with the Psidium guajava extract ameliorated damage to the pancreatic islets and enhanced lowering of blood glucose following a glucose load. Diabetes significantly decreased (P < 0.05) glycogen synthase activity by 31% compared to normal animals this being associated with a decrease in enzyme expression. Psidium guajava treatment returned the enzyme activity to near normal levels. In diabetic animals, glycogen phosphorylase activity was elevated but not significantly (P > 0.5) and treatment of both diabetic and normal animals with the extract reduced activity of the enzyme. The Psidium guajava extract also reduced glycogen phosphorylase expression in diabetic animals. Skeletal muscle glycogen content reduced by diabetes was increased as a result of treatment of diabetic animals with the Psidium guajava extract. Phytochemical analysis of the aqueous extract of Psidium guajava using Gas Chromatography-Mass Spectroscopy indicated the presence of triterpenes and phenolic compounds and we also report what we believe are three new compounds. ConclusionThe results from this study suggest that the antidiabetic effects of Psidium guajava may be due to modulation of glycogen metabolism mediated by phenolic compounds and triterpenes present in the extract.

Antibacterial Activity of &amp;lt;i&amp;gt;Psidium guajava&amp;lt;/i&amp;gt; Leaf and Stem Bark Extracts on Selected Bacteria in Ugbokolo, Benue State, Nigeria

Aim: In recent years, there has been a growing interest in researching and developing new antimicrobial agents from various sources to combat microbial resistance. The study was aimed at determining the phytochemical constituents and in vitro antibacterial activity of methanol and aqueous extracts of Psidium guajava leaves and stem bark on Escherichia coli, Salmonella typhi, Staphylococcus aureus and Proteus sp. in Ugbokolo, Nigeria. Materials and Methods: The phytochemical screening of the plant materials for various bioactive components was conducted between July and December, 2019 using standard laboratory techniques. The extracts were purified using column chromatography. The identity of the test isolates were confirmed using morphological characteristics, gram stain, motility and appropriate biochemical tests such as indole, catalase, coagulase, triple sugar iron agar. The susceptibility of the isolates to each bioactive component was determined using the agar well diffusion method. The broth dilution method was employed for the determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extracts. Results: The result of the study showed the presence of phenol, tannins, flavonoids and saponins as bioactive compounds. The antibacterial susceptibility of the isolates to aqueous and methanol extracts of leaf and stem bark of Psidium guajava varied significantly (P Staphylococcus aureus was the most susceptible isolate at 200 mg/ml concentration with average zone of inhibition of 13.05 mm for leaf extract and 15.34 mm for stem bark extract. Proteus sp. is the least susceptible with average zone of inhibition of 8.88 mm for the leaf extract and 12.36 mm for the stem bark extract respectively. Minimum Inhibitory Concentration and Minimum Bactericidal Concentration of aqueous and methanol extract of P. guajava leaf and stem bark showed that dilutions of various concentrations of aqueous and methanol extracts can inhibit and/or kill the isolates. Lower MIC (3.125 mg/ml) was shown by methanol extract than aqueous extract. MBC of methanol extract ranges between 6.25 - 25.0 mg/ml. Statistical analysis of the result showed methanol extract is more effective than aqueous extract while the stem bark of the plant showed higher efficacy than the leaf. Conclusion: The findings of the study imply that the extract of Psidium guajava has shown promising properties against tested microorganisms. Further study of the extract is therefore recommended.

EFFECT OF COMBINATION OF AQUEOUS LEAF EXTRACTS OF PSIDIUM GUAJAVA LINN AND MORINGA OLEIFERA LAM ON DIABETES MELLITUS

Objective: To determine the anti-diabetic activity of combined aqueous extracts (1:1mixture) of dry leaves of Psidium guajava linn and Moringa oleifera lam as well as to compare the anti-diabetic activity of these plants by in vitro methods.&#x0D; Methods: In vitro alpha amylase inhibitory assay was performed on porcine alpha amylase and the absorbance was measured at 540 nm using a microplate reader and glucose diffusion inhibitory assay using dialysis membrane. Acarbose was used as the standard in the above mentioned methods.&#x0D; Results: The mixture (1:1) of aqueous plant extracts (at a concentration of 100µg/ml) of Psidium guajava linn and Moringa oleifera lam exhibited 72.08333% inhibition with IC50 value of 10.9µg/ml. The leaf extracts of Psidium guajava (at a concentration 100µg/ml) exhibited 71.23288% of a α amylase inhibitory activity with an IC50 values 19.883µg/ml whereas the leaf extracts of Moringa oleifera (at a concentration of 100µg/ml) exhibited 70.58824% of α amylase inhibitory activity with an IC50 value of 27.974 µg/ml. The Acarbose (standard drug) at a concentration of 100µg/ml showed 72.09302% inhibitory effect on the α amylase activity with an IC50 value 8.9µg/ml. In glucose diffusion inhibition assay the mixture of plant extracts exhibited 76.57% inhibition at 150 min which produces more effects than the two plants. The aqueous extract of Psidium guajava leaves exhibited maximum glucose diffusion inhibition (75.32%) at 150 min as well as Moringa oleifera leaf extract showed the maximum inhibition of 73.70% at the same time interval. For acarbose the percentage was 82.74 at 150 min. The interpretation of the results was done by one-way anova method.&#x0D; Conclusion: The combined extract of the leaves of the 2 plants was found to be more effective than individual plant extracts against diabetes. On comparison of two plants Psidium guajava was found to be more active against diabetes than Moringa oleifera. Also the potentiation effect shown by the combination of extract may be due to synergistic effect of the phytochemical constituents. As the 1:1 mixture of the aqueous extract is found to be more active, the combination of the two plants can be used to formulate drugs for treating diabetes.

Development and Characterization of Phytoniosome Nano Vesicle Loaded with Aqueous Leaf Extracts of Justicia adhatoda and Psidium guajoava Against Dengue Virus (DEN-2)

The leaves of Psidium guajava (PG) and Justicia adhatoda (JA) are traditionally used in the Indian herbal medicine for the treatment of dengue. The current research work was aimed to evaluate the antiviral activity of the phytoniosomes (PN) loaded with the aqueous extracts of PG and JA (AGN) against dengue virus-2 strain (DEN-2). The AGN were prepared by ultrasonication method using tween 80, poloxamer 407, polyethylene glycol 6000 and cholesterol. The particle size of the PN was found out to be in the range of 105.1 ± 3.6–279.4 ± 5.2 nm. In comparison to the non-PEGylated niosomes, PEGylated niosomes showed lower particle size. AGN showed in vitro antiviral activity against vero cells infected with DEN-2 virus. Capsules containing AGN powder were found to be stable for 3 months when stored at room temperature. AGN4 showed maximum of 40% plaque forming units, indicating that formulation poses significant viral inhibition in in vitro condition.

Bio-inspired iron oxide nanoparticles using Psidium guajava aqueous extract for antibacterial activity

Bio-inspired synthesis of iron oxide nanoparticles (FeONPs) has been carried out by eco-friendly, low cost, and facile method using an aqueous extract of Psidium guajava (PG) leaf as a potential reducing agent. The obtained FeONPs were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and energy-dispersive spectroscopy techniques. The surface plasmon resonance peak of FeONPs was found to be 310 nm. The FTIR spectra analysis indicates the presence of various functional groups in PG extract that are responsible for the biosynthesis of FeONPs. The XRD confirmed that FeONPs were indexed into the cubic spinel lattice structure. The SEM and TEM analysis confirmed the spherical morphology of FeONPs with particle size ranging from 1 to 6 nm. The superparamagnetic nature of the formulated FeONPs was determined using VSM. The FeONPs formulated inhibit the growth of six human pathogenic strains with strong activity chiefly against Escherichia coli and Staphylococcus aureus at low concentration when compared to other standard antibacterial drugs. It is noteworthy that the formulated FeONPs are efficient as an antibacterial agent.

Toxicological Characterization of Six Plants of the Beninese Pharmacopoeia Used in the Treatment of Salmonellosis.

Recent studies reported interesting ethnopharmacological, antibacterial, and phytochemical data on some medicinal plants used in the traditional treatment of salmonellosis in Benin. Unfortunately, very little data exists on the toxicity of these species. This study aims to evaluate chemical characteristic of six Benin pharmacopoeial plants used in the traditional treatment of salmonellosis in Benin. The acute toxicity of aqueous and ethanolic extracts of Psidium guajava, Vernonia amygdalina, Cajanus cajan, Phyllanthus amarus, Uvaria chamae, and Lantana camara was evaluated according to OECD Guideline 423 at a single dose of 2000 mg/kg body weight on Wistar rats. Histological sections were performed on the liver and kidneys to confirm hematological and biochemical data. The content of aluminum, chromium, cadmium, copper, iron, lead, zinc, arsenic, selenium, and manganese was measured in 10 mg of each extract by the inductively coupled plasma optical emission spectroscopy (ICPOES) method. The results of our study generally show the absence of significant effect of the extracts on the hematological and biochemical parameters of the rats. However, with the exception of the aqueous and ethanolic extracts of Psidium guajava root and the ethanolic extract of Phyllanthus amarus (P>0.05), all the extracts have a significant effect on the aspartate aminotransferase (ASAT) level, with a variable threshold of significance (0.0001< P ≤ 0.05). No mortalities and no renal histological conditions were recorded in the treated rats. In general, the heavy metal contents of the extracts do not exceed the standards set by the WHO/FDA except for a few extracts. Arsenic was not detected in any extract, while aluminum and chromium were detected at levels above the WHO/FDA standards. On the basis of these data, it appears that the six plants studied do not show any toxicity. In view of the pharmacological and chemical data previously available, these plants are good candidates for the development of improved traditional medicines with antibacterial and particularly anti-Salmonella properties.

Eriochrome Black T sensing using silver nanoparticle-reduced graphene oxide composite via luminescent “turn-off” mechanism and its biosorption on guava (Psidium guajava) leaf powder

We report label-free sensitive and selective detection of Eriochrome Black T (EBT) in water using luminescent “turn-off” mechanism of silver nanoparticle-reduced graphene oxide composite. Silver nanoparticle-reduced graphene oxide composite was synthesized by simple and cost-effective reflux method utilizing aqueous extracts of Psidium guajava as a reducing agent and silver nitrate and graphene oxide as precursors. Silver nitrate facilitates the formation of defects in graphene in the form of graphene quantum dots. The average size of graphene quantum dots and the silver nanoparticles in the composite is $$8.9\pm 0.2$$ nm and $$27.5\pm 0.5$$ nm, respectively. By activating the plasmonic field at 350 nm excitation, these particles in the composite help in efficient detection of the dye via strong interaction with the graphene surface. The linear calibration plot for the intensity ratio was obtained with the optimized concentration of EBT between 0.1 and 7.5 $$\upmu \hbox {M}$$ . This composite material selectively detects EBT where a detection limit as low as 6.9 $$\upmu \hbox {M}$$ is achieved. In addition, the kinetics of adsorption of EBT on Psidium guajava powder are also examined. The interaction between the dye and the adsorbent follows pseudo-second-order kinetics with equilibrium adsorption capacity of 25.88 mg/g and 14.56 mg/g for 2 g/L and 5 g/L of adsorbent dose, respectively.

Evaluation of antidepressant effect of aqueous extract of Psidium guajava leaves on Wistar albino rats

Background: Depression is one of the common mental disorder prevalent worldwide. Use of herbal medicines in the treatment of depression is becoming popular because of adverse effects of existing non herbal drugs. In this study Psidium guajava leaf aqueous extract is screened for antidepressant activity in Wistar albino rats.Methods: Wistar albino rats of both sex were used. After performing acute toxicity study, dose of test drug was fixed to 100mg/kg and 200mg/kg. Test and standard drugs were administered for 10 days orally. Standard drug used was Imipramine. Antidepressant activity was assessed using forced swim test and tail suspension test.Results: Statistical analysis was done by one way ANOVA followed by Tukey Kramer. Aqueous extract of Psidium guajava leaves showed significant antidepressant activity. Both Psidium guajava aqueous extract (PGAE)-100mg/kg and 200mg/kg showed antidepressant effect but compared to 100mg/kg dose of PGAE, 200mg/kg showed significant antidepressant activity.Conclusions: From this study it can be concluded that aqueous extract of Psidium guajava leaves has antidepressant activity.

Antibacterial Activity of &amp;lt;i&amp;gt;Psidium guajava&amp;lt;/i&amp;gt; Leaf Extract against Selected Pathogenic Bacteria

This study has been embarked upon due to increased resistance of bacteria to many already synthesized drugs and the high price of the orthodox medicines in the market, the antimicrobial effect of Psidium guajava leaf extracts against selected drug-resistant bacteria will help to reduce the overdependence on orthodox or synthetic drugs which greater population of the society cannot afford due to economic/financial restriction. Ethanolic and aqueous extracts of Psidium guajava were assayed for antibacterial activity using the agar dilution method in the determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The bioactive components of the extracts were determined using standard techniques and the inhibitory activities of the extracts were compared to gentamicin, ciprofloxacin, erythromycin, azithromycin, ofloxacin, and nitrofurantoin. The MIC of the extract on the test organisms ranges from 10 mg/ml - 40 mg/ml. The sensitivity test showed that the organisms were susceptible to Psidium guajava leave extract except Pseudomonas aeruginosa. The phytochemical analysis of the extracts revealed the presence of bioactive compounds such as Tannin, Saponin, Balsam, Flavonoids, Alkaloids, Cardiac glycosides, Carbohydrate, Resins, Terpenes, and Sterols. It has been shown that the leaves of Psidium guajava have antibacterial effects and hence can be used to treat the ailments caused by those organisms at a particular dosage and concentration. However, more research work on its toxicity level, synergistic or antagonistic interaction with other plants or drugs is needed to consolidate its usage.

Tuning photoluminescence quenching efficiency of reduced graphene oxide substrates using silver nanoparticles

In this paper we report the synthesis of reduced graphene oxide doped with silver nanoparticles using aqueous extract of Psidium guajava. The dependence of photoluminescence (PL) quenching efficiency of reduced graphene oxide with variable dosage of silver nanoparticles using methylene blue as a model dye is investigated. The effect of excitation energies on the PL quenching efficiency of as-synthesized samples is also systematically studied. At 420 nm excitation, the plasmonic field of silver nanoparticles accelerates charge transfer from methylene blue to reduced graphene oxide resulting in efficient PL quenching as compared to pristine reduced graphene oxide. However at 650 nm excitation, the PL quenching efficiency of reduced graphene oxide surpasses silver nanoparticles doped reduced graphene oxide. This is attributed to strong interaction between reduced graphene oxide and methylene blue in absence of plasmonic fields at lower excitation energies. In order to enhance the quenching efficiency of silver nanoparticle doped reduced graphene oxide at 650 nm excitation, the concentration of silver nanoparticles over graphene surface is increased. This leads to increase in inhomogeneously sized and shaped nanoparticles over graphene surface which not only broadens the plasmonic absorption band but also improves the quenching efficiency at 650 nm. The schematics of charge transfer states via which the PL quenching occurs at different excitation energies are also presented.

Evaluation of antiangiogenic potential of Psidium guajava leaves using In-Ovo chick chorioallantoic membrane assay

Background: Angiogenesis is the process of formation of new blood vessels from the existing one. Pathological angiogenesis is widely implicated in many diseases, including cancer, diabetic neuropathy, retinopathy, obesity, and arthritis. Objective: The present study was aimed to evaluate the in vitro antioxidant and in ovo antiangiogenic activity of aqueous extract of Psidium guajava leaves (AEPG). Materials and Methods: Psidium guajava commonly known as guava reported to contain polyphenols and flavonoids such as gallic acid, epigallocatechin, catechin, rutin, and quercetin in glycosidic forms in its leaves. The antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), nitric oxide, hydrogen peroxide, hydroxyl, and superoxide radical scavenging assays (RSAs) and antiangiogenic activity was evaluated using vascular endothelial growth factor (VEGF)-induced chick chorioallantoic membrane (CAM).The correlation between the antioxidant and antiangiogenic activity was correlated with total phenolic content (TPC) of AEPG. Results: The TPC of AEPG was found to be 493.8 ± 8.9 mg of GAE/g. The total flavonoid content of AEPG was found to be 254.9 ± 13.7 mg of CE/g. In vitro antioxidant activity of AEPG showed IC50 values of 19.4 ± 1.9, 25.5 ± 0.2, 4.9 ± 0.5, 29.9 ± 2.06, 39.5 ± 2.07, and 29.9 ± 0.9 μg/ml, respectively, for DPPH, ABTS, nitric oxide, hydrogen peroxide, hydroxyl, and superoxide RSAs. Significant reduction in angiogenesis in the AEPG treated groups when compared to untreated VEGF groups and the Pearson's correlation coefficient between TPC of AEPG and total length, area, branches of blood vessels and CAM thickness were −0.9261, −0.9807, −0.9637, and −0.9597, respectively. Conclusion: The results revealed potent antiangiogenic activity of AEPG leaves and exhibit significant correlation between the antioxidant and antiangiogenic activity of AEPG and its TPC. Abbreviations used: EGF: Epidermal growth factor; FGF: Fibroblast growth factor; G-CSF: Granulocyte colony stimulating factor; IL: Interleukin; INF: Interferon; MMP: Matrix metalloproteinases; NOS: Nitric oxide synthase; PAF: Platelet-activating factor; PAI: Plasminogen activator inhibitor; PDGF: Platelet-derived growth factor; PG-E: Prostaglandin E; RSA: Radical scavenging assay; TFC: Total flavonoid content; TPC: Total Phenolic content; TIMP: Tissue inhibitors of metalloproteinases; TNF-α: Tumor necrosis factor alpha; VEGF: Vascular endothelial growth factor.

Aqueous extract of Psidium guajava leaves: phenolic compounds and inhibitory potential on digestive enzymes.

Leaves of Psidium guajava L. (guava) have been widely used in the popular way for prevention and treatment of various diseases. Thus, the objective of this study was to evaluate the inhibitory potential of leaves aqueous extract from three cultivars of P. guajava (Pedro Sato, Paluma and Século XXI) on α-amylase, α-glycosidase, lipase, and trypsin enzymes, in the presence or not of simulated gastric fluid and to determine the content of phenolic compounds by high performance liquid chromatography. All cultivars presented the same composition in phenolic compounds, but in different proportions. The compounds identified are gallic acid, epigallocatechin gallate, syringic acid, o-coumaric acid, resveratrol, quercetin, and catechin (which was the major compound in all the cultivars evaluated). In the absence of simulated gastric fluid, it was observed different inhibitions exercised by the leaves aqueous extracts from three cultivars of P. guajava on each enzyme. In presence of simulated gastric fluid, all cultivars showed increase in the inhibition of lipase and α-glycosidase, and decrease in inhibition of α-amylase and trypsin enzymes. These results indicate that P. guajava leaves aqueous extracts from all cultivars evaluated possess potential of use as an adjuvant in the treatment of obesity and other dyslipidemias.

Comparative evaluation of antimicrobial efficacy of an alternative natural agent for disinfection of toothbrushes.

Objective:The aim of this study was to assess the antimicrobial potency of aqueous extract of Psidium guajava leaves in two different concentrations as a toothbrush disinfectant against three oral bacterial species.Materials and Methods:Aqueous extracts of P. guajava leaves were prepared at 20% and 30% concentrations and 0.2% chlorhexidine was used as control. The toothbrushes were equally divided into 9 groups with 10 toothbrushes per disinfectant, which were contaminated with Streptococcus mutans, Lactobacillus acidophilus, and Enterococcus faecalis. Microbial culture was done after 5 min and 3 h of decontamination.Results:Group Ia and Ib showed that the presence of E. faecalis was observed in 8 (40%) of 20 toothbrushes. Group IIa and IIb showed a significant reduction in colony forming unit/toothbrush during 3 h evaluation. Group IIIa and IIIb showed nil growth during 3 h evaluation. Nil growth was observed with the control group for all three organisms. Statistically significant values were obtained for 5 min (P < 0.001) and 3 h (P < 0.001) disinfection period against L. acidophilus at two different concentrations.Conclusion:Aqueous extracts of guava leaves can be used as an alternative organic product for disinfection of toothbrushes.