Guajadials C-F, four unusual meroterpenoids from Psidium guajava

Guajadials C-F(1-4),four sesquiterpenoid-based meroterpenoids with unprecedented skeletons were isolated from the leaves of Psidium guajava.Their structures and relative configurations were established by extensive spectroscopic analysis.A possible biosynthetic pathway for 1-4 was also proposed.

Determination of 2 Flavonoids in Psidium guajava Linn. from Different Habitats in Guizhou

[ Objective] This study was conducted to determinate the contents of hyperoside and isoquercitrin in the leaves of Psidium guajava Linn. from different areas of Guizhou Province, which would provide data support for production and quality control of P. guajava leaf material. [ Method] The contents of hypereside and isoquercitrin were measured by HPLC under following conditions： Agilent XDB-C18,4.6 mm x 250 ram, 5 ttm, CH3CN-0.1% HCOOH （13： 87） as mobile phase, column temporature at 25 ℃, detection wavelength of 257 mn and flow rate at 1.0 ml/min. [ Result ] The results showed that leaves of P. guajava from dif- ferent producing areas contained variable hypereaide and isoquercitrin contents in the same period, and the differences in quality were obvious between different are- as. [ Conclusion] The method for detecting the contents of hypereside and isoquercitrin in P. guajava leaf materials is simple with reliable accurate results. The P. guajava leaf material produced in Gouting Township, Luedian County has better quality.

Advances in Pharmacological Research of Psidium Guajava L.Leaves in Resisting Diabetes and Its Complications

Modern pharmacological studies have shown that Psidium Guajava L.leaves have a variety of pharmacological effects,such as anti-inflammation,anti-oxidation,anti-tumor,reducing blood lipid,and reducing blood sugar.In recent years,the effect of Psidium Guajava L.leaves on diabetes and its complications has become the focus of research.This paper reviews the pharmacological research trends of effect of Psidium Guajava L.leaves on diabetes and its complications,in order to provide reference for the application and research and development of this plant.

Antibacterial Activity of Psidium guajava 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.

Antibacterial Activities of <i>Psidium guajava</i>(Guava) and <i>Velvet tamarin</i>(Icheku) Local Chewing Sticks on <i>Streptococcus mutans</i>Isolated from Human Mouth

Globally dental diseases are mainly caused by Streptococcus mutans, it is one of the leading causative agents of dental caries worldwide, because of its resistance to conventional antibacterial agents, alternative therapies are used to control resistance of oral pathogens. This research was done to determine the antibacterial activities of Psidium guajava (guava) and Velvet tamarin (Icheku) chewing sticks on Streptococcus mutans isolated from the oral cavity. The study was conducted in Owerri Imo State Nigeria during November-December period. Phytochemical analysis of the plant extracts was done using appropriate techniques. The procedure used for antimicrobial susceptibility test was disk diffusion method. Serial dilutions of Psidium guajava (guava) and Velvet tamarind (Icheku) extracts were prepared, Muller-Hinton media was used to put together the extract of serial dilutions of Psidium guajava (guava) and Velvet tamarin (Icheku) and a microbiological procedure were used for visually determining the minimum inhibitory concentration as well as minimum bactericidal concentration. Phytochemical evaluation of the plants’ extracts revealed that it contains saponins, tannins, alkaloid, steriods, glycosides and phenol. The results obtained from the antibacterial susceptibility testing of the extracts against Streptococcus mutans showed that the zones of inhibition recorded ranged from 18 mm to 27 mm. Ethanol (Soxhlet) extract of Icheku twig showed no zone of inhibition on the isolated organism. The ethanol (soxhlet) extract of the individual Psidium guajava (guava) and Velvet tamarin (Icheku) has a better antibacterial effect when compared to their aqueous extracts and combined forms. Psidium guajava (Guava) and Velvet tamarin (Icheku) twigs are made up of composite that is active against S. mutans and can be used in oral hygiene. There is a need for further investigation on the plant extracts as the rural poor make use of it because it is cheap, readily available and the rich also use it once they are in the village mostly in Eastern Nigeria. Similarly chewing sticks has been reported to be practiced by 90 of rural population in Nigeria.

番石榴(Psidium guajava L.)资源的ISSR分析初报

用ISSR技术分析16份番石榴资源的亲缘关系。结果表明:从11条能扩增出较清晰多态性指纹图谱的引物中,筛选出了6条引物能对所有资源均扩增出可重复的清晰指纹,共扩增出44条可重复带,其中多态性带占61.4%;扩增结果可将16份供试资源一一分开,部分资源存在同名异物现象;各资源间的相似系数在0.689～0.981之间,平均为0.841。UPGMA聚类结果将16份资源分成了3组。

Phytochemical Composition and Antioxidant Capacity of Psidium guajava Fresh Fruits and Flour

Psidium guajava fruits are consumed fresh or processed (beverages, syrup, ice cream, jams and jellies). Guayaba is a fruit highly perishable and susceptible to damage during the postharvest. One strategy to overcome this problem is its processing by using techniques that preserve its organoleptic, nutritive and functional properties and allow getting food with added value. The purpose of this study was to obtain flour from fresh fruits cultivated in Argentina Northwestern by lyophilization and to determine the antioxidant activity and the main phytochemicals present in fresh fruits and flour. Nutritional composition (sugar, protein and fat) and the bioactive phytochemicals (total phenolic compounds, flavonoid phenolic, condensed and hydrolizable tannin, ascorbic acid, pigments such as anthocyanin and carotenoids) as well as fiber content, were evaluated. The flour preserved flavor, aroma and color of pulp from fresh fruits. The flour contained around 30% of sugar, 20% of total protein, 0.5% of fat and high level of crude fiber. Carotenoids and ascorbic acid were the dominant phytochemicals in flour as well as in fresh fruits. The guayaba flour showed antioxidant activity with SC50 values similar to fresh fruits. The flour showed nutraceutical characteristics that are demanded by functional food and could be used as a dietary supplement.

Growth Kinetics of Vegetative and Reproductive Organs of Guava(Psidium guajava L.)in Iguala Guerrero,Mexico

In the Mexican tropics the guava trees can grow and produce in any season, so they can be har-vested out of the period of high competition marketing (Summer). It?studied the growth kinetics of leaves and fruits of guava trees at the dry tropical conditions of the State of Guerrero, in guava trees of four years old and was evaluated a non-destructive method for measuring leaf area from November to May. 100 sheets of 10 randomly selected trees were cut. It was found that leaf length X the width X 0.72581647 (conversion factor) gave an estimated leaf area which?was significantly correlated with that obtained by the integrator of leaf area. Both in length and width the leaf growth kinetics were sigmoid with three growth stages: In Stage I (15 days) leaves grew 21.2% and 21.5%;in Stage II (26 days) grew 73.6% and 68%;and in Stage III (30 days). They Increased 5.2% and 10.5% in the primary and secondary sprouts. The fruit growth in its equatorial and polar diameters corresponded to a double sigmoid kinetics. In Stage I (61 days) it reached 1.9 and 2.3 cm;in Stage II (62 - 102 days) it reached 3.09 and 3.62 cm;and in Stage III (103 to 126 days) it reached 4.63 and 5.13 cm, as well the physiological maturity of fruit.

Effects of two medicinal plants Psidium guajava L. (Myrtaceae) and Diospyros mespiliformis L. (Ebenaceae) leaf extracts on rat skeletal muscle cells in primary culture

Crude decoction, aqueous and ethanolic extracts of two medicinal plants (Psidium guajava and Diospyros mespili- formis), widely used in the central plateau of Burkina Faso to treat many diseases were evaluated for their antagonistic effects on caffeine induced calcium release from sarcoplasmic reticulum of rat skeletal muscle cells. These different extracts showed a decrease of caffeine induced calcium release in a dose dependent manner. Comparison of the results showed that Psidium guajava leaf extracts are more active than extracts of Diospyros mespiliformis and that crude decoctions show better inhibitory activity. The observed results could explaine their use as antihypertensive and antidiarrhoeal agents in traditional medicine, by inhibiting intracellular calcium release.

Guava extract (Psidium guajava) alters the labelling of blood constituents with technetium-99m

Psidium guajava (guava) leaf is a phytotherapic used in folk medicine to treat gastrointestinal and respiratory dis-turbances and is used as anti-inflammatory medicine. In nuclear medicine, blood constituents (BC) are labelled with techne-tium-99m (99mTc) and used to image procedures. However, data have demonstrated that synthetic or natural drugs could modify the labelling of BC with 99mTc. The aim of this work was to evaluate the effects of aqueous extract of guava leaves on the labelling of BC with 99mTc. Blood samples of Wistar rats were incubated with different concentrations of guava extract and labelled with 99mTc after the percentage of incorporated radioactivity (%ATI) in BC was determined. The results suggest that aqueous guava extract could present antioxidant action and/or alters the membrane structures involved in ion transport into cells, thus decreasing the radiolabelling of BC with 99mTc. The data showed significant (P<0.05) alteration of ATI in BC from blood incubated with guava extract.

Antidiabetic and antidiarrhoeal effects on ethanolic extract of Psidium guajava(L.) Bat.leaves in Wister rats

Objective:To evaluate the antidiabetic and the antidiarrhoeal effects of ethanolic extracts of Psidium guajava leave(EEPGL) in Wisier rais to support its traditional uses.Methods:Oral glucose tolerance test model and alloxan induced diabetic test model were performed to evaluate antidiabetic activity of EEPGL at doses of 1.00.0.50 and 0.75 g/kg respectively.For antidiarrhoeal effects of EEPGL.castor oil-induced diarrhoea model and gastrointestinal motility test with barium sulphate milk model were also assessed at doses of750.500 and 250 mg/kg.respectively.Results:Administration of EEPGL at doses 1.00 and 0.50 g/kg significantly(P<0.05)decreased blood glucose levels in oral glucose tolerance test model as well as 0.75 g/kg dose in alloxan induced diabetic test model in Wister rats(P<0.001).Application of EEPGL at doses of 750 and 500 mg/kg showed antidiarrhoeal effect in castor oil-induced diarrhoeal model(P<0.00 l and P<0.01,respectively),and 750 mg/kg(P<0.01),500 and 250 mg/kg(P<0.05)doses in barium sulphate milk model in aforesaid animals.Conclusions:These results exhibited the significant antidiabetic and antidiarrhoeal activities of ethanolic extracts of Psidium guajava leave in Wister rats.

Therapeutic Effects of Essential Oil from Waste Leaves of <i>Psidium guajava</i>L. against Cosmetic Embarrassment Using Phylogenetic Approach

Medicinal plants are facing threats due to loss of habitat and overexploitation of knows species. Therefore the present work shows utilization of essential oil from discarded leaves of Psidium guajava Linn. against human dermatophytic fungi Trichophyton rubrum, T. mentagrophytes, Trichophyton violaceum, Trichophyton tonsurans, Epidermophyton floccosum, Microsporum gypseum and Microsporum canis. The oil was found to be fungicidal at 3.0 μl/ml and it tolerated heavy inoculum of pathogens at fungicidal concentrations. The fungicidal activity of the oil was thermostable, up to 70°C and shelf life was found to be six months, which was maximum the time taken into consideration. The oil having cineole, caryophyllane, copaene, azulene and eucalyptol as main constituents, exhibited broad fungicidal activity. The oil did not show any adverse effect on mammalian skin upto 5% concentration. Phylogeny of the dermatophytes with respect to toxicity of the oil has also been discussed using molecular data. The cost effective formulation from waste leaves can be exploited after undergoing double blind successful multicentral topical testing.

Hepatoprotective Effect of Guava (<i>Psidium guajava</i>L.) Leaf Extracts on Ethanol-Induced Injury on Clone 9 Rat Liver Cells

Guava (Psidium guajava L.), a tropical fruit, belongs to Myrtaceae family. Leaves and fruits of guava have been reported to have an anti-diarrheal, hypoglycemic, lipid lowering, anti-bacterial in addition to antioxidant activities. The aim of this study was to investigate several guava leaf extract cytotoxic effects on healthy clone 9 liver cells and its hepatoprotective effects on ethanol-induced heap-toxicity. It was discovered that when the clone 9 liver cells were treated with guava (Psidium guajava Linn.) extracts for 24 hours, there was no retardation of growth as well as when ethanol and acetone extracts at low concentrations 100 μg/mL and 50 μg/mL were administered however cytototoxic effects were detected at higher concentrations. Water and hot water extracts in concentrations lower than or equal to 500 μg/mL revealed no cytotoxic effects. Injury induction to healthy clone 9 liver cells using 5% alcohol concentration for 30 minutes revealed the hepatoprotective properties of guava (Psidium guajava Linn.) extracts. This was significant in concentrations of 100 μg/mL or lower for ethanol and all concentrations for hot water extracts. Hot water extracts showed higher hepatoprotective and lower cytotoxic properties than other extracts.

Antibacterial Activity of <i>Psidium guajava</i>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.

Green synthesis of titanium dioxide nanoparticles using Psidium guajava extract and its antibacterial and antioxidant properties

Objective:To determine the efficacies of antibacterial and antioxidant activities of aqueous leaf extract of Psidium guajava mediated biosynthesis of titanium dioxide nanoparticles(TiO_2,NPs).Methods:Synthesized TiO_2 NPs were tested by disc diffusion method against against human pathogenic bacteria.The total antioxidant activity and phenolic content(Folin—Ciocalteau method) of synthesized TiO_2 NTs and aqueous plant extract were determined.The scavenging radicals were estimated hv DPPH method.The synthesized TiO_2 NPs were characterized by XRD,FTIR.FESEM and EDX,Results:FTIR spectra of synthesized TiO_2 NPs exhibited prominent peaks at 3410 cm^(-1)(alkynes),1 578 cm^(-1).1 451 cm^(-1)(alkanes),and 1 123 cm^(-1)(C-O absorption).The morphological characterization of synthesized TiO_2 NPs was analysed by FESEM which showed spherical shape and clusters with an average size of 32.58 nm.The maximum zone of inhibition was observed in the synthesized TiO_2 NPs(20 μg/mL) against Staphylococcus aureus(25 mm) and Escherichia coli(23 mm).The synthesized TiO_2 NPs showed more antibacterial activity than the standard antibiotic disk,tetracycline which drastically reduces the chances for the development of antibiotics resistance of bacterial species.The plant aqueous extract and synthesized TiO_2NPs were found to possess maximum antioxidant activity when compared with ascorbic acid.The content of phenolic compounds(mg/g) in Leaf aqueous extract and synthesized TiO_2 NPs were found to be 85.4 and 18.3 mgTA/g,respectively.Conclusions:Green synthesized TiO_2 NPs provides a promising approach can satisfy the requirement of large-scale industrial production hearing the advantage of low—cost,eco—friendly and reproducible.

Clonal propagation of guava (Psidium guajava Linn.) by stem cutting from mature stockplants

The study describes the scope of clonal propagation of guava (Psidium guajava Linn.) by stem cutting collected from mature stockplants. Cuttings were treated with 0, 0.2%, 0.4% and 0.8% IBA solution and rooted in the non-mist propagator. Rooted cuttings were allowed to grow in the polybags filled with soil and cow-dung mixed in the ratio of 3: 1 (by volume) for three months to assess the steckling capacity and initial growth performance. The study reveals that the species is amenable for clonal propagation by mature stem cutting. The highest rooting percentage (60%) was observed in the cuttings treated with 0.4% IBA solution followed by 0.2% IBA and the lowest was in controlled cuttings. The maximum number of primary root (32.7) was developed in the cuttings treated with 0.8% IBA solution followed by 0.4% IBA and the lowest was in the cuttings without IBA treatment. The highest survival percentage (70.9) was observed in the cuttings rooted with 0.4% IBA treatment and the lowest (58.3) was in the cuttings without any treatment. However, there was no significant variation in height growth of cutlings due to IBA treatments in rooting.

Biogenic Synthesis of Silver Nanoparticles Using Guava (<i>Psidium guajava</i>) Leaf Extract and Its Larvicidal Action against <i>Anopheles gambiae</i>

The progress in the field of nanotechnology has contributed to the development of tools for combating the most critical problems in developing countries. The requirements that such tools should meet are low-cost and resource settings, environmental protection, ease of use, and availability. The use of plant properties for the generation of nanoparticles (NPs), which serve as bioinsecticides to combat the plasticity and resistance of mosquitoes and parasites, is considered possible. Here, we report for the first time the larvicidal activity of silver (Ag) NPs (AgNPs) synthesized from Psidium guajava (P. guajava) extract, which targets the 4th instar larvae of Anopheles gambiae. Concentrations of AgNPs between 0 and 200 ppm were used and their LC50 at 24 h and 48 h were determined as 19.55 ppm and 8.737 ppm, respectively. The AgNPs were stable and highly effective against the larvae of A. gambiae and thereby we anticipate that they can be used to combat vector-borne diseases in developing countries.

A review of meroterpenoids and of their bioactivity from guava(Psidium guajava L.)

Psidium guajava Linn.(family Myrtaceae),is commonly known as guava.Guava is consumed in large quantities throughout the world due to its ease of cultivation and high nutritional value.As an important perennial fruit tree distributed around the world,guava has been widely used to manage various diseases in traditional medicine.Guava has been shown significant bioactivity such as antioxidant,anti-inflammatory,immunomodulatory,antimicrobial,antidiabetic,and anticancer properties.A large number of studies indicated that guava contains various type of phytochemicals including monoterpenes,sesquiterpenes,triterpenes,phenolics,and meroterpenoids.Among them,meroterpenoids are characteristic components of guava,which are hybrid of acylphloroglucinol with terpenoids(monoterpenes,sesquiterpenes).Modern pharmacological investigations showed intricate Psidium meroterpenoids possess a wide range of bioactivities.Although a large and growing body of literatures have investigated the Psidium meroterpenoids isolated from guava,a comprehensive review of Psidium meroterpenoids and their bioactivities has not been conducted.Therefore,this review provides a comprehensive compile of 75 meroterpenoids isolated from guava and their bioactivities between 2007 and May 2022.Furthermore,the possible biosynthesis way and future directions of Psidium meroterpenoids have also been discussed.

Seed Extract of Psidium guajava as Ecofriendly Corrosion Inhibitor for Carbon Steel in Hydrochloric Acid Medium

The anticorrosion characteristics of the seeds of Psidium guajava （P. guajava） fruits on carbon steel in acid medium were examined with weight loss data and subsequently thermodynamic factors such as heat of ad- sorption of the inhibitor on the metal surface （Q）, change in entropy （ΔS）, change in flee energy of the reaction （ΔG）, corrosion rate （CR） and energy of activation for corrosion reaction of carbon steel （E） were also evaluated. Adsorption isotherm was plotted to study the adsorption of the inhibitor on the metal surface with increasing concentration of the inhibitor. The functional groups responsible for inhibition were investi- gated using Fourier transform infrared （FT-IR） spectra. Electrochemical parameters were evaluated through the potentiodynamic Tafel polarization and impedance spectral studies. Scanning electron microscopy （SEM） micrographs were recorded to investigate the change in surface morphology. The complete study reveals the efficiency of seed extract of P. guajava as a safe, ecofriendly and alternate corrosion inhibitor for carbon steel in acid medium.

Guajamers A-I, Rearranged Polycyclic Phloroglucinol Meroterpenoids from Psidium guajava Leaves and Their Antibacterial Activity

Eight new polycyclic phloroglucinol meroterpenoids guajamers A-H(1-8),a methylated benzoylphloroglucinol meroterpenoid guajamer I(9)representing a new skeleton,and two known analogues(10 and 11)were isolated from the leaves of Psidium guajava.The structures of new molecules were elucidated by detailed analysis of spectroscopic data,and those of 1,2,8,and 9 were unambiguously confirmed by single-crystal X-ray diffraction study.Structurally,compounds 1-8 were sesquiterpene and monoterpene-based meroterpenoids with rearranged skeletons,while compound 9 was the first case of 3-alkyl-5-formyl-benzoylphloroglucinol-coupled sesquiterpene containing an unusual C-l-spiro-fused 6/6/9/4 polycyclic skeleton.In addition,all the isolated compounds were evaluated for their antibacterial activity against three bacterial strains,and most of them(compounds 2-7,10,and 11)showed antibacterial activity against Staphylococcus aureus and Staphylococcus epidermidis with MIC values of 8-32 μmol/L.These findings suggested that meroterpenoids isolated from Psidium guajava can be considered as potential antibacterial leading compounds for pharmaceutical industry.