Psidium guajava: A Single Plant for Multiple Health Problems of Rural Indian Population

Edible Medicinal Guava Fruit (Psidium guajava L.) Are a Source of Anti-Biofilm Compounds against Pseudomonas aeruginosa

Psidium guajava is one of the most common edible medicinal plants frequently used in Malagasy traditional medicine to treat gastrointestinal infections. In order to evaluate their probable antibacterial activities, three organic extracts (successive extractions by hexane, dichloromethane, and ethanol) of ripe guava fruits were assessed for their bactericidal and anti-virulence properties against P. aeruginosa PAO1. Although these three extracts have shown no direct antibacterial activity (MIC of 1000 µg/mL) and, at the non-bactericidal concentration of 100 µg/mL, no impact on the production of major P. aeruginosa PAO1 virulence factors (pyocyanin and rhamnolipids), the hexane and dichloromethane extracts showed significant anti-biofilm properties and the dichloromethane extract disrupted the P. aeruginosa PAO1 swarming motility. Bioguided fractionation of the dichloromethane extract led to the isolation and identification of lycopene and β-sitosterol-β-D-glucoside as major anti-biofilm compounds. Interestingly, both compounds disrupt P. aeruginosa PAO1 biofilm formation and maintenance with IC50 of 1383 µM and 131 µM, respectively. More interestingly, both compounds displayed a synergistic effect with tobramycin with a two-fold increase in its effectiveness in killing biofilm-encapsulated P. aeruginosa PAO1. The present study validates the traditional uses of this edible medicinal plant, indicating the therapeutic effectiveness of guava fruits plausibly through the presence of these tri- and tetraterpenoids, which deserve to be tested against pathogens generally implicated in diarrhea.

Boosting Solanum tuberosum resistance to Alternaria solani through green synthesized ferric oxide (Fe2O3) nanoparticles

Potato (Solanum tuberosum) is the third crucial global crop facing threats from Alternaria solani, a necrotrophic fungal pathogen causing early blight disease. Beyond crop impact, it leads to substantial production reduction and economic losses worldwide. This study introduces a green synthesis method for producing Ferric Oxide nanoparticles (FNPs) using dried Guava (Psidium guajava) leaves. Guava leaf extract acts as a reducing agent, with iron (III) chloride hexahydrate (FeCl3·6H2O) as the oxidizing agent. This study employed various characterization techniques for Ferric Oxide nanoparticles (FNPs). Fourier Transform Infrared Spectroscopy (FTIR) revealed peaks at 877 cm-1, 1180 cm-1, 1630 cm-1, 1833 cm-1, 2344 cm-1, and 3614 cm-1, associated with Maghemite vibrations, polyphenol compounds, and amino acids. UV-Vis spectroscopy exhibited a characteristic absorbance peak at 252 nm for FNPs. Scanning Electron Microscope (SEM) images illustrated particle sizes of 29-41 nm, and Energy Dispersive Spectroscopy (EDS) indicated elemental composition. X-ray diffraction (XRD) confirmed crystalline FNPs with peaks at 26.78, 30.64, 36.06, 38.21, 43.64, 53.52, 57.42, 63.14 and 78.32. Disease resistance assays demonstrated FNPs' effectiveness against A. solani, reducing disease incidence and severity. In the leaf detach assay, concentrations of 15, 10 and 5 mg/L showed a dose-dependent reduction in disease severity and incidence. The Greenhouse Assay confirmed FNPs' concentration-dependent effect on disease incidence and severity. The study also explored FNPs' potential as biocontrol agents showing no adverse effects on overall plant development. Additionally, the study highlighted the agronomic potential of FNPs in enhancing plant growth and development emphasizing their role as micronutrients in biofortification. The findings suggest the promising application of FNPs in plant protection and biofortification strategies.

Assessing the potential of Psidium guajava derived phytoconstituents as anticholinesterase inhibitor to combat Alzheimer's disease: an in-silico and in-vitro approach

Acetylcholinesterase (AChE) inhibitors play a crucial role in the treatment of Alzheimer's disease. These drugs increase acetylcholine levels by inhibiting the enzyme responsible for its degradation, which is a vital neurotransmitter involved in memory and cognition. This intervention intermittently improves cognitive symptoms and augments neurotransmission. This study investigates the potential of Psidium guajava fruit extract as an acetylcholinesterase (AChE) inhibitor for Alzheimer's disease treatment. Molecular characteristics and drug-likeness were analyzed after HR-LCMS revealed phytocompounds in an ethanolic extract of Psidium guajava fruit. Selected phytocompounds were subjected to molecular docking against AChE, with the best-docked compound then undergoing MD simulation, MMGBSA, DCCM, FEL, and PCA investigations to evaluate the complex stability. The hit compound's potential toxicity and further pharmacokinetic features were also predicted. Anticholinesterase activity was also studied using in vitro assay. The HR-LCMS uncovered 68 compounds. Based on computational analysis, Fluspirilene was determined to have the highest potential to inhibit AChE. It was discovered that the Fluspirilene-AChE complex is stable and that Fluspirilene has a high binding affinity for AChE. Extract of Psidium guajava fruit significantly inhibits AChE (88.37% at 200 μg/ml). It is comparable to the standard AChE inhibitor Galantamine. Fluspirilene exhibited remarkable binding to AChE. Psidium guajava fruit extract demonstrated substantial AChE inhibitory activity, indicating its potential for Alzheimer's treatment. The study underscores natural sources' significance in drug discovery.Communicated by Ramaswamy H. Sarma.

Psidium guajava: An Insight into Ethnomedicinal Uses, Phytochemistry, and Pharmacology

BACKGROUND

Psidium guajava (guava) is widely distributed in tropical and subtropical regions and adapted to various environmental conditions. Guava is an important economic fruit widely used as food and folk medicine. It contains flavonoids, alkaloids, tannins, triterpenoids, reducing sugars, essential oils, carotenoids, polyphenols, etc. The presence of triterpenoid acids such as guavacoumaric, ursolic, jacoumaric, guajavanoic, guavenoic, and Asiatic acids helps to develop novel drugs against various diseases. It is used traditionally for medicinal purposes, mainly for antioxidant, antimicrobial, antispasmodic, antidiabetic, anticancer, antiallergy, anti-inflammatory, and hepato-protective properties.

OBJECTIVE

The systematic literature study aims to summarize its botanical description, phytochemicals, pharmacological activities, and clinical trials. This review focuses on the plant's chemical composition and scientific approaches to human welfare.

METHODS

A systematic literature search was done on Psidium guajava through previous literature and online databases such as Google Scholar, Pubmed, Science Direct, etc., to explain its ethnomedicinal uses, phytochemistry, and pharmacological applications.

RESULTS

Previous literature studies of Psidium guajava suggest it can serve as antioxidant, antimicrobial, antispasmodic, antidiabetic, anticancer, anti-allergy, anti-inflammatory, and hepatoprotective effects. Successful clinical trials performed on the plant extracts against infantile rotaviral enteritis and infectious gastroenteritis showed future directions to work with the plant for clinical applications.

CONCLUSION

In this review, an attempt is made to show all literature studied, especially in phytochemistry, pharmacology, clinical trials and uses as traditional folk medicine around the world. The leaves have been used by folklore over the years to treat various ailments such as skin ulcers, diarrhoea, vaginal irritation, cough, conjunctivitis, etc. Further studies are required to explore more therapeutic remedies and to develop new medicines for future perspectives.

Nutritional Composition, Mineral Profiling, In Vitro Antioxidant, Antibacterial and Enzyme Inhibitory Properties of Selected Indian Guava Cultivars Leaf Extract

Psidium guajava L. is a small evergreen tree known for its magnificent medicinal and nutritional value. This study aimed to evaluate the nutritional profile and in vitro pharmacological potentialities of the different leaf extracts of four cultivars of Psidium guajava namely Surka chitti, Allahabad safeda, Karela, and Lucknow-49. The standard procedures of the Association of Official Analytical Chemists (AOAC) were followed to carry out the nutritional analysis and all of the cultivars recorded the presence of elements at a nominal range. The highest presence of phenols (125.77 mg GAE/g) and flavonoids (92.38 mg QE/g) in the methanolic leaf extract of the Karela cultivar was recorded. A wide range of minerals such as sodium, phosphorus, magnesium, zinc, and boron were recorded with a higher percentage in the Karela cultivar of Psidium guajava. In the enzyme inhibitory assays, Allahabad safeda showed potential inhibition with an IC50 of 113.31 ± 1.07, 98.2 ± 0.66 and 95.73 ± 0.39 μg/mL in α-amylase, α-glucosidase, and tyrosinase inhibition assays, respectively. The strong antioxidant effect was established by Lucknow-49 (IC50 of 74.43 ± 1.86 μg/mL) and Allahabad safeda (IC50 of 78.93 ± 0.46 μg/mL) for ABTS and DPPH assays, respectively. The ethyl acetate and methanolic leaf extracts of the Allahabad safeda cultivar showed better inhibition against Pseudomonas aeruginosa with an MIC of 14.84 and 28.69 µg/mL, respectively. A decent mean zone of inhibition was recorded in methanolic leaf extract that ranged from 21-25 mm in diameter against the tested bacterial strains (Proteus vulgaris, Bacillus subtilis, and P. aeruginosa). This is the first scientific report on the comparative and comprehensive analysis of indigenous guava cultivars to evidently shortlist the elite cultivars with enriched dietary nutrition and biological activities.

Aroma-based discrimination of Egyptian versus Indian guava fruits and in response to probiotics as analyzed via SPME/GC-MS and chemometric tools

Guava tree (Psidium guajava L., Myrtaceae) is an economic grown worldwide, particularly in tropical and subtropical regions. Guavas encompass numerous cultivars (cvs.) that were discriminated in previous studies based on leaf morphological features and profile of volatile organic compounds (VOCs). Nevertheless, fruit VOCs have also shown outstanding potential for discrimination of other plant taxa, which has not been utilized in guava. Hence, the current study investigates the various guava cvs. harvested from India and Egypt. A total of 5 samples were analyzed by solid phase microextraction coupled to gas chromatography/mass spectrometry. Results led to the detection of 42 VOCs belonging to aldehydes, alcohols, esters, ketones, aliphatic and aromatic hydrocarbons, in addition to monoterpene and sesquiterpene hydrocarbons. Butylated hydroxytoluene and β-caryophyllene were predominant reaching 77% and 41% in Egyptian and Indian guava, respectively. The impact of probiotic fermentation, i.e., Lactobacillus acidophilus and L. plantarum on aroma profile was not significantly different (p > 0.05). Multivariate data analyses were further applied for samples classification and markers determination, including principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). PCA score plot showed clear segregation of Egyptian from Indian specimens, whereas OPLS-DA revealed that β-caryophyllene was associated with white fruit versus 3-butenyl isothiocyanate and muurolol in red fruit type in the case of Indian guava. The richness of Egyptian guava in butylated hydroxytoluene in addition to the presence of vitamin C may potentiate its antioxidant activity, to be followed in subsequent studies regarding its health effects.

Antimicrobial Activity of Psidium guajava Aqueous Extract against Sensitive and Resistant Bacterial Strains

The inappropriate use of antimicrobials, along with environmental conditions, can lead to the emergence of resistant microorganisms. The use of phytopharmaceuticals and herbal medicines has a positive impact and represents a promising alternative. Psidium guajava extracts have been widely reported to have antimicrobial potential; however, studies reporting their activity against resistant bacterial strains are scarce. Because of the emerging resistance, the aim of this study was to analyze the antimicrobial capacity of the aqueous extract of guava leaves against wild-type and resistant bacterial strains. The aqueous extract obtained from the leaves of P. guajava was evaluated by HPLC for the content of total phenolics and tannins, antioxidant activity, and chemical composition. The antimicrobial activity of the extracts was analyzed by the disk diffusion and broth microdilution methods. The results of the chemical analysis of the extracts showed total phenolics content of 17.02 ± 6.87 mg/g of dry extract, total tannin content of 14.09 ± 1.20 mg of tannic acid equivalents/g of dry extract, and moderate antioxidant capacity with an EC₅₀ value of 140 µg/mL. Flavonoids are the major compounds (rutin, hesperidin, and quercetin), followed by phenolic acids. Disk diffusion test results showed the presence of inhibition halos for Gram-positive bacteria (Staphylococcus aureus, sensitive and resistant; Staphylococcus pseudintermedius, sensitive and resistant; and Streptococcus spp., beta-hemolytic), while for Gram-negative bacteria (Escherichia coli, sensitive and resistant), there was no inhibition in the tested concentration range. The Minimal Inhibitory Concentration was 6.8 mg/mL for all Gram-positive strains evaluated. The present study demonstrated the antimicrobial activity of the aqueous extract of P. guajava against sensitive and resistant Gram-positive bacteria. The better antimicrobial activity found in the present study compared with previously reported activity should be highlighted and may be related to the higher concentration of total phenolics present in the tested extract. Moreover, the content of tannins found suggests a species with high quality that produces tannins. These new findings suggest an innovative profile regarding therapeutic resources that can be adopted to combat resistant microbial strains.

Clinical outcomes associated with complementary and alternative medicine-related "immunity-boosting" practices in patients with cirrhosis during the COVID-19 pandemic - an observational study

During the coronavirus disease 2019 pandemic, Ayurvedic herbal supplements and homeopathic immune boosters (IBs) were promoted as disease-preventive agents. The present study examined the clinical outcomes among patients with chronic liver disease who presented with complications of portal hypertension or liver dysfunction temporally associated with the use of IBs in the absence of other competing causes. This single-center retrospective observational cohort study included patients with chronic liver disease admitted for the evaluation and management of jaundice, ascites, or hepatic encephalopathy temporally associated with the consumption of IBs and followed up for 180 days. Chemical analysis was performed on the retrieved IBs. From April 2020 to May 2021, 1022 patients with cirrhosis were screened, and 178 (19.8%) were found to have consumed complementary and alternative medicines. Nineteen patients with cirrhosis (10.7%), jaundice, ascites, hepatic encephalopathy, or their combination related to IBs use were included. The patients were predominantly male (89.5%). At admission, 14 (73.75%) patients had jaundice, 9 (47.4%) had ascites, 2 (10.5%) presented with acute kidney injury, and 1 (5.3%) had overt encephalopathy. Eight patients (42.1%) died at the end of the follow up period. Hepatic necrosis and portal-based neutrophilic inflammation were the predominant features of liver biopsies. IB analysis revealed detectable levels of (heavy metals) As (40%), Pb (60%), Hg (60%), and various hepatotoxic phytochemicals. Ayurvedic and Homeopathic supplements sold as IBs potentially cause the worsening of preexisting liver disease. Responsible dissemination of scientifically validated, evidence-based medical health information from regulatory bodies and media may help ameliorate this modifiable liver health burden.

In Vitro Dengue Virus Inhibition by Aqueous Extracts of Aegle marmelos, Munronia pinnata and Psidium guajava

Dengue is an arboviral (insect-transmitted) infection of global concern. Currently, there are still no specific dengue antiviral agents to treat the disease. Plant extracts have been used in traditional medicine for treating various viral infections - thus, in the present study, aqueous extracts of dried flowers of Aegle marmelos (AM), whole plant of Munronia pinnata (MP) and leaves of Psidium guajava (PG) were investigated for their potential capacity to inhibit dengue virus infection of Vero cells. The maximum non-toxic dose (MNTD) and the 50% cytotoxic concentration (CC₅₀) were determined by using the MTT assay. A plaque reduction antiviral assay was carried out with dengue virus types 1 (DV1), 2 (DV2), 3 (DV3) and 4 (DV4), in order to calculate the half-maximum inhibitory concentration (IC₅₀). AM extract inhibited all four virus serotypes tested; MP extract inhibited DV1, DV2 and DV4, but not DV3; PG extract inhibited DV1, DV2 and DV4, but not DV3. Thus, the results suggest that AM is a promising candidate for the pan-serotype inhibition of dengue viral activity.

Composition, Antibacterial Efficacy, and Anticancer Activity of Essential Oil Extracted from Psidium guajava (L.) Leaves

Essential oils (EO) are used as a natural remedy to treat various chronic diseases, although clinical evidence is lacking. In this context, we have endeavored to measure the percentage of chemical composition and biological efficacy of Psidium guajava (guava) leaf essential oil in treating oral infections and oral cancer. The essential oil obtained from hydrodistillation of P. guajava L. leaves was analyzed by gas chromatography−mass spectrometry (GC−MS). The activities of selected oral pathogens Candida albicans (C. albicans) and Streptococcus mutans (S. mutants) were studied in vitro and in silico. MTT assay was used to test for anticancer activity against human oral epidermal carcinoma (KB). GC−MS showed that the main components of PGLEO were limonene (38.01%) and β-caryophyllene (27.98%). Minimum inhibitory concentrations (MICs) of 0.05−0.1% were demonstrated against C. albicans and S. mutans. Antimicrobial activity against C. albicans and S. mutans, as shown by molecular linkage analysis, revealed that the main metabolites, limonene and β-caryophyllene, potentially inhibited the receptors of C. albicans and S. mutans. PGLEO showed significant (p < 0.001) anticancer activity (45.89%) at 200 µg/mL compared to doxorubicin (47.87%) with an IC50 value of 188.98 µg/mL. The outcomes of the present study suggest that PGLEO has promising antimicrobial and anticancer activities and could be a useful source for developing a natural therapeutic agent for oral infections and oral cancer.

Medicinal plants used for the management of respiratory diseases in Zimbabwe: Review and perspectives potential management of COVID-19

Respiratory diseases have in the recent past become a health concern globally. More than 523 million cases of coronavirus disease (COVID19), a recent respiratory diseases have been reported, leaving more than 6 million deaths worldwide since the start of the pandemic. In Zimbabwe, respiratory infections have largely been managed using traditional (herbal) medicines, due to their low cost and ease of accessibility. This review highlights the plants' toxicological and pharmacological evaluation studies explored. It seeks to document plants that have been traditionally used in Zimbabwe to treat respiratory ailments within and beyond the past four decades. Extensive literature review based on published papers and abstracts retrieved from the online bibliographic databases, books, book chapters, scientific reports and theses available at Universities in Zimbabwe, were used in this study. From the study, there were at least 58 plant families comprising 160 medicinal plants widely distributed throughout the country. The Fabaceae family had the highest number of medicinal plant species, with a total of 21 species. A total of 12 respiratory ailments were reportedly treatable using the identified plants. From a total of 160 plants, colds were reportedly treatable with 56, pneumonia 53, coughs 34, chest pain and related conditions 29, asthma 25, tuberculosis and spots in lungs 22, unspecified respiratory conditions 20, influenza 13, bronchial problems 12, dyspnoea 7, sore throat and infections 5 and sinus clearing 1 plant. The study identified potential medicinal plants that can be utilised in future to manage respiratory infections.

Macroporous adsorptive resin-assisted enrichment of polyphenol from Psidium guajava leaves improved its in vitro antioxidant and anti-hemolytic properties

Phytochemical analyses of guava leaf extracts, commonly applied in traditional medicine, revealed the presence of several bioactive polyphenols. In this study, we optimized the enrichment of total polyphenol from Guava leaf ethanolic extract (GEE) using six macroporous adsorptive resins (MAR) including AB8, D101, X5, ADS17, S400, and AD7. Also investigated are the contributions of adsorption time, extract concentration, pH, elution time, and eluent ethanol concentrations on the polyphenol enrichment potential of MAR. The antioxidant and anti-hemolytic properties of the crude and polyphenol-rich extracts were determined. Our results indicate that treatment of GEE extract with AB8 MAR at a concentration of 15 mg GEE/g resin, adsorption time of 45 min, elution time of 40 min, and eluent ethanol concentration of 50% (v/v) improved the flavonoids and phenol concentration of GEE by 2 and 2.5 folds respectively. The DPPH radical scavenging, ferric reducing ability of the plasma (FRAP), anti-hemolytic and anti-peroxidation activity of the resultant polyphenol-rich extracts improved by 1.5, 1.6, 1.4, and 1.88 folds respectively, when compared to the crude extract. Our work shows that the MAR-assisted enrichment operation is a rapid, feasible, and economical strategy for enriching bioactive polyphenols from guava leaf extracts.

Guava Leaf Essential Oil as a Potent Antioxidant and Anticancer Agent: Validated through Experimental and Computational Study

Several drugs now employed in cancer therapy were discovered as a result of anticancer drug research based on natural products. Here, we reported the in vitro antioxidant and anticancer activity followed by in silico anticancer and estrogen-like activity of Psidium guajava L. essential oil against ER-α receptors which lead to potential inhibitory action against breast cancer pathways.

METHODS

The bioactive compounds in guava essential oil were screened using gas chromatography-mass spectrometry (GC-MS). Similarly, the antioxidant properties of the extracted oil were evaluated using 2,2-Diphenyl-1-picrylhydrazyl scavenging assay. Furthermore, the in vitro anticancer activity of guava oil was observed through the MTT assay and an in silico molecular docking experiment was also carried out to ensure that they fit into the estrogen receptors (ERs) and possess anticancer potential.

RESULTS

The GC-MS profile of the essential oil revealed the presence of 17 chemicals, with limonene (51.3%), eucalyptol (21.3%), caryophyllene oxide (6.2%), caryophyllene (5.6%), and nerolidol (4.5%) occupying more than one-third of the chromatographic spectrum zone. Guava leaves' essential oil (EO) inhibited DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and exhibited concentration dependent free radical scavenging activity, acting as a potent antioxidant with an IC50 value of 29.3 ± 0.67 µg/mL. The outcome of the MTT assay showed that the extracted guava oil had nearly the same efficacy against breast and liver cancer cells at a low concentration (1 µg/mL), giving 98.3 ± 0.3% and 98.5 ± 0.4% cell viability against HepG2 at 1 µg/mL, respectively. When the concentration of essential oil was increased, it showed a small reduction in the percentage of viable cells. While conducting an in silico study of all the screened compounds, the potential for hydroxycaryophyllene, caryophyllene, caryophyllene oxide, humulene, terpineol, and calamenene to inhibit tumor growth was bolstered due to a resemblance to 4-hydroxytamoxifen, thereby implying that these compounds may act as selective estrogen receptor modulators (SERMs). The ADME analysis of the compounds indicated above revealed that they exhibit excellent drug likeness properties and follow the Lipinski rule of five.

CONCLUSIONS

Consequently, they have a substantial anticancer therapeutic potential and can be used for novel drug discovery in the effort to minimize the global burden of breast cancer.

Guava Leaf Extract Suppresses Fructose Mediated Non-Alcoholic Fatty Liver Disease in Growing Rats

Purpose

Fructose is highly lipogenic, and its unhindered ingestion by children and adolescents is understood to induce hypertriglyceridemia and non-alcoholic fatty liver disease (ped-NAFLD) that is till date managed symptomatically or surgically. The aim of the present study was to investigate the potential of hydroethanolic extract of leaves of Guava (PG-HM) to suppress the alterations in the hepatic molecular signals due to unrestricted fructose (15%) drinking by growing rats.

Methods

Weaned rats (4 weeks old) in control groups had ad libitum access to fructose drinking solution (15%) for four (4FDR) or eight (8FDR) weeks, ie, till puberty or early adulthood, respectively, while treatment groups (4PGR, 8PGR) additionally received PG-HM (500 mg/kg, po).

Results

The PG-HM suppressed ped-NAFLD through hepatic signalling pathways of 1) leptin-insulin (Akt/FOX-O1/SREBP-1c), 2) hypoxia-inflammation (HIF-1ɑ/VEGF, TNF-ɑ), 3) mitochondrial function (complexes I–V), 4) oxidative stress (MDA, GSH, SOD) and 5) glycolysis/gluconeogenesis/de novo lipogenesis (hexokinase, phosphofructokinase, ketohexokinase, aldehyde dehydrogenase). Parri passu, the insulin sensitizing effect of PG-HM and its ethyl acetate fraction (PG-EA) was elucidated using HepG2 cells grown in media enhanced with fructose. Further, in murine hepatocytes cultured in fructose-rich media, PG-HM (35 µg mL-1) outperformed Pioglitazone (15 µM) and Metformin (5 mM), to suppress hepatic insulin resistance.

Conclusion

This study established that hydroethanolic extract of leaves of Guava (PG-HM) has potential to suppress hepatic metabolic alteration for the management of the pediatric NAFLD.

Exploring the Role of Antioxidants to Combat Oxidative Stress in Malaria Parasites

BACKGROUND

Malaria, a global challenge, is a parasitic disease caused by Plasmodium species. Approximately 229 million cases of malaria were reported in 2019. Major incidences occur in various continents, including African and Eastern Mediterranean Continents and South-East Asia.

INTRODUCTION

Despite the overall decline in global incidence from 2010 to 2018, the rate of decline has been almost constant since 2014. The morbidity and mortality have been accelerated due to reactive oxygen species (ROS) caused by oxidative stress generated by the parasite responsible for the destruction of host metabolism and cell nutrients.

METHODS

The excessive release of free radicals is associated with the infection in the animal or human body by the parasites. This may be related to a reduction in nutrients required for the generation of antioxidants and the destruction of cells by parasite activity. Therefore, an intensive literature search has been carried out to find the natural antioxidants used to neutralize the free radicals generated during malarial infection.

RESULTS

The natural antioxidants may be useful as an adjuvant treatment along with the antimalarial chemotherapeutics to reduce the death rate and enhance the success rate of malaria treatment.

CONCLUSION

In this manuscript, an attempt has been made to provide significant insight into the antioxidant activities of herbal extracts against malaria parasites.

Isolation and Characterization of Aeromonas jandaei from Nile Tilapia in Lake Volta, Ghana, and Its Response to Antibiotics and Herbal Extracts

Production of Nile Tilapia Oreochromis niloticus contributes to economic growth in many countries. However, there has been a decline in its production over the years due to the influx of bacterial infections, with Aeromonas jandaei as an emerging threat. In this study, we identified and characterized A. jandaei from cage-cultured Nile Tilapia in Akosombo Stratum II of Lake Volta in Ghana and evaluated its response to commonly used antibiotics using the disc diffusion and agar well diffusion methods for herbal extracts at various concentrations (10, 30, 50, 70, and 100 mg/mL). The herbs considered included guava Psidium guajava leaf, bitter leaf Vernonia amygdalina, neem Azadirachta indica leaf, and their cocktail (GBNL in the ratio of 1:1:1). The bacterium was isolated from swab samples from the head kidneys of 27 moribund Nile Tilapia collected from nine fish farms. Samples were screened for A. jandaei by culturing and identification using morphological and molecular techniques. The bacterium isolate from fish in the study, identified as A. jandaei GH-AS II, had 92-93% identity to A. jandaei reference strains. Infection of healthy Nile Tilapia (n = 210) with the bacterium isolate showed that 1.0 × 10⁵  CFU/mL was the lethal dose causing 50% mortality. Antibiotic susceptibility testing showed that A. jandaei GH-AS II was resistant to tetracycline and ampicillin. Herbal extracts at the various concentrations inhibited the growth of the bacterium isolate, with a significant increment in the zones of inhibition with increasing concentrations of leaf extracts. However, GBNL showed prominence compared to the other extracts only at 100 mg/mL. Management of A. jandaei GH-AS II by using herbal extracts at Nile Tilapia farms in Lake Volta may be recommended since the use of antibiotics, such as tetracycline and ampicillin, may not yield the needed result.

Natural products for the treatment and management of diabetes mellitus in Zimbabwe-a review

Use of medicinal plants and herbs in the treatment and management of diseases, including diabetes mellitus and its complications remains an integral part of African tradition. In Zimbabwe, nearly one million people are living with diabetes mellitus. The prevalence of diabetes mellitus in Zimbabwe is increasing every year due to lifestyle changes, and has accelerated the use of traditional medicines for its treatment and management in urban areas. In addition, the high cost of modern medicine has led many people in rural parts of Zimbabwe to rely on herbal plant medicine for the treatment of diabetes mellitus and its complications. This review highlights a number of studies carried out to evaluate the antidiabetic properties of indigenous plants found in Zimbabwe with the goal of treating diabetes mellitus. Further, we discuss the mechanism of action of various plant extracts in the treatment and management of diabetes mellitus. Together, this review article can open pathways leading to discovery of new plant derived medicines and regularization of use of crude plant remedies to treat diabetes mellitus by the Zimbabwean government and others across Africa.

Development of rice based probiotic yogurt enriched with some fruit pulps and its quality analysis

Yogurt is one of the popular dairy products produced by the bacterial fermentation of milk. Researches proved that fruit enriched Rice-based yogurt is good alternative for the traditional yogurt. Hence, four different combinations of rice-based yogurt were prepared by adding rice slurry. Rice-based yogurt containing 25% milk and 75% rice slurry scored best in microbial analysis. Count of both Streptococcus salivarius ssp. thermophilus and Lactobacillus delbrueckii ssp. bulgaricus were higher in this combination but organoleptic quality was poor. The one with 75% milk and 25% slurry scored best in organoleptic analysis as it scored high in all the characters under study. Hence the combination with 75% milk and 25% slurry was selected and was enriched with the fruit pulps of Annona, Papaya and Guava. The one with 20% Annona fruit pulp and one with 5% Papaya fruit pulp were selected as the best combinations as they got the highest overall acceptability score and the count of both the bacteria were higher in these combinations, proved that fruit enrichment doesn't affect bacteria in yogurt. Cost analysis proved that collection of fruits from wild will help to reduce the price of the yogurt. Thus, Rice-based Probiotic Yogurt with 75% milk and 25% rice slurry with 20% Annona fruit pulp and one with 5% Papaya fruit pulp were developed as best combinations and can replace normal yogurts currently available in the market with low cost.

Minor tropical fruits as a potential source of bioactive and functional foods

Tropical fruits are defined as fruits that are grown in hot and humid regions within the Tropic of Cancer and Tropic of Capricorn, covering most of the tropical and subtropical areas of Asia, Africa, Central America, South America, the Caribbean and Oceania. Depending on the cultivation area covered, economic value and popularity these tropical fruits are divided into major and minor tropical fruits. There is an annual increment of 3.8% in terms of commercialization of the tropical fruits. In total 26 minor tropical fruits (Kiwifruit, Lutqua, Carambola, Tree Tomato, Elephant apple, Rambutan, Bay berry, Mangosteen, Bhawa, Loquat, Silver berry, Durian, Persimon, Longan, Passion fruit, Water apple, Pulasan, Indian gooseberry, Guava, Lychee, Annona, Pitaya, Sapodilla, Pepino, Jaboticaba, Jackfruit) have been covered in this work. The nutritional composition, phytochemical composition, health benefits, traditional use of these minor tropical fruits and their role in food fortification have been portrayed.

Guava (Psidium guajava L.): a glorious plant with cancer preventive and therapeutic potential

Guava (Psidium guajava L.) tree (Myrtaceae family) bears fruit rich in vitamins, fiber, and other nutrients. While native to Latin America, guava is grown in many tropical and subtropical regions across the globe where it has long been used in traditional medicine to treat a myriad of ailments. Guava has been shown to exhibit a number of biological and pharmacological activities, such as antioxidant, anti-inflammatory, immunomodulatory, antimicrobial, antidiabetic, and anticancer properties. Several parts of the plant, including the leaves, fruits, seeds, peels, pulp, bark, and oil, produce phytochemicals with medicinal properties. Emerging research has found that guava bioactive phytochemicals exert antitumorigenic effects against various human malignancies through multiple mechanisms. While there are numerous individual studies that document the anticancer effects of guava constituents, an up-to-date, comprehensive, and critical review of available research data has not been performed. Therefore, the purpose of this review is to present a complete analysis of the cancer preventive and anticancer therapeutic potential of guava-derived products and guava constituents, with a focus on the cellular and molecular mechanisms of action. The bioavailability, pharmacokinetics, and toxicity of guava as well as limitations, challenges, and future directions of research have also been discussed.

Pharmacological Effects of Guava (Psidium guajava L.) Seed Polysaccharides: GSF3 Inhibits PC-3 Prostate Cancer Cell Growth through Immunotherapy In Vitro

The inhibitory effects of purified fractions isolated from guava seed polysaccharides (GSPS) including guava seed polysaccharide fraction 1 (GSF1), GSF2, and GSF3 on prostate cancer cells remain unclear. To clarify the anti-prostate cancer potential, GSPS, GSF1, GSF2, and GSF3 were isolated using Sepharose 6B gel filtration chromatography to assay their inhibitory effects on prostate PC-3 cell growth with direct action or indirect immunotherapy using either splenocyte conditioned media (SCM) or macrophage conditioned media (MCM). Correlations between cytokine profiles in the conditioned media and pro-apoptotic gene expression levels in the corresponding treated PC-3 cells were analyzed. Results showed that GSPS, GSF1, GSF2, and GSF3, particularly GSF3, through either direct action or indirect treatments using SCM or MCM, significantly (p < 0.05) inhibited PC-3 cell growth. GSF3 direct treatments increased pro-apoptotic Bax/anti-apoptotic Bcl-2 mRNA expression ratios in corresponding treated PC-3 cells. Either SCM or MCM cultured with GSF3 increased Fas mRNA expression levels in corresponding treated PC-3 cells. Both Th2-polarized and anti-inflammatory cytokine IL-10 either secreted in SCM or MCM were positively correlated with Fas mRNA expression levels in corresponding treated PC-3 cells. Our results suggest that GSF3 is a potent biological response modifier to decrease PC-3 cell growth through inducing apoptosis.

1H nuclear magnetic resonance-based metabolite profiling of guava leaf extract: an attempt to develop a prototype for standardization of plant extracts

Background

Herbal medicines are fast gaining popularity. However, their acceptability by modern practitioners is low which is often due to lack of standardization. Several approaches towards standardization of herbals have been employed. The current study attempted to recognize key peaks from ¹H NMR spectra which together would comprise of a spectral fingerprint relating to efficacy of Psidium guajava (guava) leaf extract as an antidiarrhoeal when a number of unidentified active principles are involved.

Methods

Ninety samples of guava leaves were collected from three locations over three seasons. Hydroalcoholic (water and ethanol, 50:50) extracts of these samples were prepared and their ¹H NMR spectra were acquired. Spectra were also obtained for quercetin, ferulic acid and gallic acid as standards. Eight bioassays reflecting different stages of diarrhoeal pathogenesis were undertaken and based on pre-decided cut-offs, the extracts were classified as ‘good’ or ‘poor’ extracts. The bioactivity data was then correlated with the ¹H NMR profiles using Regression or Orthogonal Partial Least Square-Discriminant Analysis (OPLS-DA).

Results

OPLS-DA showed seasonal and regional segregation of extracts. Significant models were established for seven bioassays, namely those for anti-bacterial activity against Shigella flexneri and Vibrio cholerae, adherence of E. coli, invasion of E. coli and S. flexneri and production and binding of toxin produced by V. cholerae. It was observed that none of the extracts were good or bad across all the bioassays. The spectral analysis showed multiple peaks correlating with a particular activity. Based on NMR and LC-MS/MS, it was noted that the extracts contained quercetin, ferulic acid and gallic acid. However, they did not correlate with the peaks that segregated extracts with good and poor activity.

Conclusions

The current study identified key peaks in ¹H NMR spectra contributing to the anti-diarrhoeal activity of guava leaf extracts. The approach of using spectral fingerprinting employed in the present study can thus be used as a prototype towards standardization of plant extracts with respect to efficacy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03221-5.

Effect of Psidium guajava (guava) L. Leaf Decoction on Antibiotic-resistant Clinical Diarrhoeagenic Isolates of Shigella spp

Background: Although shigellosis is self-limiting, antibiotics are recommended to minimize the severity of symptoms and reduce mortality rates. However, due to the increasing reports of antibiotic resistance, alternative approaches are needed to combat shigellosis. Interest for research on medicinal plants has increased in recent years, and hence, they can be explored to treat this infectious diarrhoea. Objective: To study the effect of Psidium guajava L. (guava) leaf decoction (GLD) on the antibiotic-resistant clinical isolates of Shigella spp. Materials and Methods: A total of 43 isolated Shigella spp. from diarrhoeal patients were used in this study. The effect of GLD on the bacterial viability was initially assessed. The isolates were divided into two categories: sensitive and resistant to GLD. For sensitive isolates, antibacterial activity of GLD was evaluated while for resistant strains, the ability of GLD for reducing the bacterial invasion of the HEp-2 cell line underwent an investigation. Results: Among the 43 Shigella isolates, GLD affected the growth of 23 strains. The invasion of 9 strains from the 20 remaining resistant isolates was unaffected. Although the number of isolates was less, the data suggested that isolates belonging to S. flexneri serogroup were more sensitive to GLD in comparison with other spp (i.e., sonnei, boydii, and dysenteriae). Conclusion: The results of this study revealed the efficacy of GLD against drug-resistant Shigella spp. and thus could be considered for the treatment of diarrhoea. GLD can be a cost-effective alternative to antibiotics.

Anxiolytic activity of Psidium guajava in mice subjected to chronic restraint stress and effect on neurotransmitters in brain

The anxiolytic activity of Psidium guajava L. leaf ethanolic extract (PLE) and its effect on neurotransmitter systems was investigated. PLE, extracted using Soxhlet apparatus, was subjected to preliminary qualitative and quantitative (flavonoids and phenols) analyses. The anxiolytic activity at 100, 200, and 400 mg/Kg doses were assessed in mice using elevated plus maze (EPM) and light/dark transition (LDT) test models on days 1 and 16. Neurotransmitters such as monoamines (serotonin, norepinephrine, and dopamine), γ-aminobutyric acid (GABA), and glutamate were estimated in different regions of the brain (cortex, hippocampus, and cerebellum and brain stem). Phytoconstituents identified using gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry were analyzed in silico to evaluate their potential binding mode(s) to GABA_A and 5-HT_1A receptors. Phytochemical studies showed the presence of alkaloids, tannins, flavonoids, saponins, anthraquinone glycosides, carbohydrates, and proteins, whereas total flavonoid and phenol contents were estimated to be 64.96 ± 0.95 and 206.58 ± 1.60 mg/g of dried extract, respectively. PLE treatment significantly enhanced exploratory activity of mice in EPM and LDT models with significant effects on monoamines, GABA and glutamate levels in the brain. The in silico studies suggested the interaction(s) of PLE component(s) with GABA_A /5-HT_1A receptors as a potential mechanism of its anxiolytic activity.

Antiplasmodial and Genotoxic Study of Selected Ghanaian Medicinal Plants

Results

Five out of the eight plants, A. boonei stem bark, S; siamea Lam root, M. lucida Benth leaves, P. niruri, and A. hispidum DC whole plants, showed varying degrees of antiplasmodial activity against the asexual stage of the parasite. The most active extract against chloroquine-sensitive (3D7) and chloroquine-resistant (Dd2) P. falciparum strains is the A. hispidum extract which yielded a mean inhibitory concentration at 50% (IC₅₀) of 3.66 µg/ml and 3.71 µg/ml for 3D7 and Dd2, respectively. This was followed by S. siamea Lam with 3.95 µg/ml for 3D7 and 4.47 µg/ml for Dd2. The IC₅₀ values of the A. boonei extract against 3D7 and Dd2 P. falciparum parasites were 5.13 µg/ml and 3.62 µg/ml, respectively. For the M. lucida Benth extract, the least IC₅₀ value was 6.46 µg/ml. All five extracts exhibited dose-dependent antiplasmodial activity. Assessment of the genotoxic effects the A. hispidum extract by the comet assay revealed substantial damage to P. falciparum DNA.

Conclusion

This study demonstrates that the crude extract of A. hispidum DC, one of the plants used traditionally to treat malaria, inhibits the growth of P. falciparum in vitro and could be a potential source of antimalarial drug. The report has highlighted genotoxic and cytotoxic effects of the selected plant extracts on human leukocytes as well.

A randomized open label efficacy clinical trial of oral guava leaf decoction in patients with acute infectious diarrhoea

Background

Diarrhoea is amongst the first ten causes of death and its treatment faces an increased threat of drug resistance. Previous studies on the guava leaf decoction (GLD) revealed its suitability for use in infectious diarrhoea of unknown etiology.

Objective

The objective of this trial was to establish efficacy, dose and safety of GLD prepared from the Indian Sardar variety in adults with acute infectious diarrhoea.

Methods

The current trial was an open efficacy randomized 5-day, parallel group multi-arm interventional study. Amongst 137 adults (18–60 years) suffering with acute diarrhoea, 109 were included (57% females, 43% males). Three doses of GLD (6-leaf, 10-leaf and 14-leaf) were compared with controls receiving oral rehydration solution. Decrease in stool frequency and improvement in consistency were the outcomes measured. The data was analyzed using ANOVA, Tukey's post-hoc test, Kruscal-Wallis test and Chi-Square test where applicable.

Results

The trial showed that the 14-leaf (7.4 g) decoction was the most effective. Administration of the decoction, thrice daily helped the patients regain normalcy in 72 h as opposed to 120 h in controls. Safety of the intervention was reflected by normal levels of haemoglobin, liver and kidney parameters. No adverse events were reported.

Conclusion

The 14 leaves decoction was a safe treatment for adult acute uncomplicated diarrhoea of unknown etiology. Moreover due to component synergy and divergent mechanisms of action, it could possibly combat the generation of drug resistance and destruction of gut microbiota. Hence GLD has the potential for development as a first line treatment for diarrhoea.

Trial registration

Trial was registered with Clinical Trials Registry - India (CTRI registration number: CTRI/2016/07/007095). The trial was retrospectively registered.