Metabolomic Comparison of Guava (Psidium guajava L.) Leaf Extracts Fermented by Limosilactobacillus fermentum and Lactiplantibacillus plantarum and Their Antioxidant and Antiglycation Activities.

Probiotic fermentation of plant-based materials can lead to the generation of various bioactive substances via bacterial metabolites and the biotransformation of phenolic compounds. We compared the metabolic differences between fermentation by Limosilactobacillus fermentum KCTC15072BP (LFG) and fermentation by Lactiplantibacillus plantarum KGMB00831 (LPG) in guava leaf extract (0%, 0.5%, and 2% (w/v))-supplemented medium via non-targeted metabolite profiling. By performing multivariate statistical analysis and comparing the different guava leaf extract groups, 21 guava-derived and 30 bacterial metabolites were identified. The contents of guava-derived glucogallin, gallic acid, and sugar alcohols were significantly higher in LFG than they were in LPG. Similarly, significantly higher contents of guava-derived pyrogallol, vanillic acid, naringenin, phloretin, and aromatic amino acid catabolites were obtained with LPG than with LFG. LFG led to significantly higher antioxidant activities than LPG, while LPG led to significantly higher antiglycation activity than LFG. Interestingly, the fermentation-induced increase in the guava-leaf-extract-supplemented group was significantly higher than that in the control group. Thus, the increased bioactivity induced by guava fermentation with the Lactobacillaceae strain may be influenced by the synergistic effects between microbial metabolites and plant-derived compounds. Overall, examining the metabolic changes in plant-based food fermentation by differentiating the origin of metabolites provides a better understanding of food fermentation.

Probiotic Yogurt Supplemented with Lactococcus lactis R7 and Red Guava Extract: Bioaccessibility of Phenolic Compounds and Influence in Antioxidant Activity and Action of Alpha-amylase and Alpha-glucosidase Enzymes.

The industry has increasingly explored the development of foods with functional properties, where supplementation with probiotics and bioactive compounds has gained prominence. In this context, the study aimed to evaluate the influence of in vitro biological digestion on the content of phenolic compounds, antioxidant activity, and inhibition of α-amylase and α-glucosidase activities of probiotic yogurt supplemented with the lactic acid bacteria Lactococcus lactis R7 and red guava extract (Psidium cattleianum). A yogurt containing L. lactis R7 (0.1%) and red guava extract (4%) was characterized for the content of phenolic compounds, antioxidant activity, and potential for inhibition of digestive enzymes after a simulated in vitro digestion process. After digestion, the caffeic and hydroxybenzoic acids remained, and sinapic acid only in the last digestive phase. Antioxidant activity decreased during digestion by 28.93, 53.60, and 27.97% for DPPH, nitric oxide and hydroxyl radicals, respectively, and the inhibition of the α-amylase enzyme decreased only 4.01% after the digestion process. α-glucosidase was more efficient in intestinal digestion, demonstrating an increase of almost 50% in probiotic yogurt with red guava extract before digestion. Possibly, the phenolics change their conformation during digestion, generating new compounds, reducing antioxidant activity, and increasing the inhibitory activity of α-glucosidase digestive enzymes. It was concluded that the probiotic yogurt formulation supplemented with red guava extract could interfere with the concentration of phenolic compounds and the formation of new compounds, suggesting a positive and effective inhibition of the digestive enzymes, even after the digestive process.

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.

Evaluation of 28-day repeated doses oral toxicity of essential oil from Psidium glaziovianum Kiaersk leaves on various biological parameters in Swiss mice.

Only a small number of the many medicinally important species in the genus Psidium L. have had their safety assessed. Psidium glaziovianum, a plant native to Brazil, is reported to exert antinociceptive and anti-inflammatory effects; however, there are no apparent reports of long-term safety following administering of repeated doses. The aim of this study was to examine the effects of 28-day oral of treatment at 250, 500 or 1,000 mg/kg Psidium glaziovianum essential oil (PgEO) on behavioral and physiological parameters in male and female Swiss mice. First, PgEO was chemically characterized by gas chromatography mass spectrometry (GC-MS). The following parameters were examined: motor activity, body temperature, blood glucose, urine, hematology, biochemistry, histology, and oxidative stress. Characterization of PgEO revealed 48 components which were dominated by sesquiterpenes 1,8-cineol (24.29%), α-pinene (19.73%) and ß-pinene (17.31%). Data showed that PgEO treatment in mice increased activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) without markedly affecting body weight, hematological or biochemical parameters, as well as water or food consumption. Administration of PgEO in repeated daily dosages over 28 days did not significantly alter exploratory or locomotor activities. Based upon our findings, PgEO administration daily for 28 days, exhibited low toxicity and absence of effects on the nervous system. Data demonstrated that PgEO produced hypoglycemic and antioxidant actions which need to be considered in safety assessment.

Chemical composition, antinociceptive and anti-inflammatory effects in mice of the essential oil of Psidium cattleyanum Sabine leaves.

ETHNOPHARMACOLOGICAL RELEVANCE: One of the native species of the genus most often mentioned by traditional people is Psidium cattleyanum Sabine, which is used mostly to treat disorders of the respiratory, genitourinary, and digestive systems. These symptoms are mainly treated by the decoction of the leaves. Additionally, there are gaps in the in vivo and toxicity investigations of this species. AIM OF THE STUDY: The aim of this study was evaluate antinociceptive and anti-inflammatory potential of essential oil from P. cattleyanum leaves in vivo. MATERIALS AND METHODS: Gas chromatography-mass spectrometry (GC/MS) was used to examine the essential oil of P. cattleyanum. The acute toxicity test was then done with a 2000 mg/kg dosage. The oil at 50, 100, and 200 mg/kg orally, as well as the reference medications Morphine 10.0 mg/kg IP and/or Indomethacin 20.0 mg/kg IP, were tested using nociception (abdominal writhing, formalin, and tail immersion) and inflammatory models (paw edema and peritonitis). RESULTS: The phytochemical assay showed a high concentration of ß-caryophyllene (46.68%) and α-caryophyllene (10.81%). In the in vivo assays, P. cattleyanum essential oil proved to be an important antinociceptive agent, reaching 76.96% inhibition of abdominal writhing with acetic acid and 67.12% in the formalin assay. An increase in latency time in the tail test was also reported. In the test with carrageenan, the oil showed significant inhibition compared to the control. A decrease in the migration of leukocytes was also reported in the group treated with P. cattleyanum, reaching 60.49% at the dose of 200 mg/kg. CONCLUSIONS: The essential oil from the leaves of P. cattleyanum has anti-inflammatory and antinociceptive action and has potential for application in the pharmaceutical and food industry.

Fishing the Targets of Bioactive Compounds from Psidium guajava L. Leaves in the Context of Diabetes.

Psidium guajava L. (guava) leaves have demonstrated their in vitro and in vivo effect against diabetes mellitus (DM). However, there is a lack of literature concerning the effect of the individual phenolic compounds present in the leaves in DM disease. The aim of the present work was to identify the individual compounds in Spanish guava leaves and their potential contribution to the observed anti-diabetic effect. Seventy-three phenolic compounds were identified from an 80% ethanol extract of guava leaves by high performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry. The potential anti-diabetic activity of each compound was evaluated with the DIA-DB web server that uses a docking and molecular shape similarity approach. The DIA-DB web server revealed that aldose reductase was the target protein with heterogeneous affinity for compounds naringenin, avicularin, guaijaverin, quercetin, ellagic acid, morin, catechin and guavinoside C. Naringenin exhibited the highest number of interactions with target proteins dipeptidyl peptidase-4, hydroxysteroid 11-beta dehydrogenase 1, aldose reductase and peroxisome proliferator-activated receptor. Compounds catechin, quercetin and naringenin displayed similarities with the known antidiabetic drug tolrestat. In conclusion, the computational workflow showed that guava leaves contain several compounds acting in the DM mechanism by interacting with specific DM protein targets.

Self-Emulsifying Micellization of Crude Extracts from Apple (Malus domestica cv. Anna), Plum (Prunus domestica cv. Satsuma), and Guava (Psidium guajava L.) Fruits.

Micellar microemulsions are thermodynamically stable self-emulsifying systems that have been used to successfully improve the low oral bioavailability of several bioactive phytochemicals, such as antioxidant polyphenols. However, most studies have reported the micellization of single-compounds or purified chemical fractions; thus, the stability, phytochemical-loading efficiency, and bioactivity of complex crude extracts remain largely unexplored. In this study, we evaluated the effects of micellar emulsification of tropical apple (Malus domestica cv. Anna), plum (Prunus domestica cv. Satsuma), and guava (Psidium guajava L.) extracts regarding particle size and stability, polyphenol-loading efficiency, antioxidant capacity, and cytotoxic activity in human and murine cells. Simple food-grade extraction protocols were implemented to obtain apple, plum, and guava extracts. Total polyphenols, flavonoids, and antioxidant activity (DPPH) were determined in the fruit extracts, and their polyphenol profile was further characterized by liquid chromatography (HPLC-DAD). The dried extracts were mixed into a food-grade, self-emulsifying system, and their cytotoxicity in human and murine cell lines was compared. Our research showed that complex fruit matrixes were successfully emulsified into thermodynamically stable polysorbate-based nanometric micelles with uniform size distribution and consistent pH stability, with potential applications in food and biomedical industries.

Effect and mechanism of norfloxacin removal by guava leaf extract in the ZVI/H2O2 system.

To overcome the bottlenecks of the conventional zero-valent iron Fenton-like (ZVI/H2O2) process, such as low reagent utilization, low applicable pH, and iron sludge contamination, guava leaf extract (GLE) was used as a green promoter to enhance ZVI/H2O2 process in this study. Compared with the ZVI/H2O2 system, the removal rate and kobs of norfloxacin by the ZVI/H2O2/GLE system were increased by 33.76% and 2.19 times, respectively. The experimental investigation of the mechanism showed that the attack of reactive oxygen species was the main pathway for the removal of pollutants, and three types of reactive oxygen species (1O2, O2-,·OH) generations in the ZVI/H2O2/GLE system were effectively promoted by the introduction of GLE. The reactivity improvement was mainly due to the decrease of pH. At the same time, the chelation of iron ions by GLE promoted the Fe(III)/Fe(II) cycle on the catalyst surface was also a minor mechanism to improve the reactivity. This study provides a crucial reference for the practical application of guava leaf to promote the ZVI/H2O2 process in environmental pollution control.

Preparation, structural characterization, and bioactivities of polysaccharides from Psidium guajava: A review.

Psidium guajava L. is one of the most pivotal members belong to the Myrtaceae family, and it is an important tropical fruit with highly nutritional, healthy, and pharmacological values prevailing in worldwide for decades. The polysaccharides of P. guajava (PGPs) are served as one of the most active constituents, which possess a variety of biofunctionalities including anti-inflammatory, antidiarrheic, antihypertension, and antidiabetic properties. Hence, a systematic review aimed to comprehensively summarize the recent research advances of PGPs is necessary for facilitating their better understanding. The present review discussed current research progress on the PGPs, including extraction and purification methods, structural features, biological activities, and potential pharmacological mechanism. In addition, this review may also provide some valuable insights for further development and potential value in affording functionally useful agents in food industry or therapeutically effective medicine in the fields of P. guajava polysaccharides.

Silk nanoparticles for the protection and delivery of guava leaf (Psidium guajava L.) extract for cosmetic industry, a new approach for an old herb.

Guava (Psidium guajava L.) is a well-known plant containing high levels of natural antioxidants, the phenolic compounds, which have been employed in numerous cosmetic products. However, these molecules are unstable to oxidants, light, temperature, pH, water, and enzymatic activities. Therefore, to enhance their stability and preserve their antioxidant activity, this study investigated the silk fibroin nanoparticles (SFNs) ability to encapsulate, deliver, and heat-protect the phenolic compounds of the guava leaves ethanolic extract. Firstly, the guava ethanolic extract was produced by maceration, which possessed a total phenolic content of 312.6 mg GAE/g DPW and a high antioxidant activity (IC50 = 5.397 ± 0.618 µg/mL). Then, the extract loaded SFNs were manufactured by desolvation method, and the particles demonstrated appropriate sizes of 200-700 nm with narrow size distribution, spherical shape, silk-II crystalline structure, high drug entrapment efficiency of > 70% (dependent on the fibroin content), and a two-phase sustained drug release for at least 210 min. Using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, the antioxidant activity of the guava extract was well-preserved in the extract loaded SFNs. Finally, after being treated with high temperature of 70 °C for 24 h, the guava extract almost loses all of its antioxidant property (5 times decrement), whereas the extract loaded SFNs could retain the extract activity. Conclusively, the SFNs proved much potential to deliver and heat-protect the guava extract phenolic compounds, and preserve their antioxidant activity. Confirmed by this case, SFNs could be further explored in protecting other natural compounds from environmental factors.

The improvement of guava (Psidium guajava) juice quality using crude multi-enzymatic extracts obtained from yeasts.

Guava juice is cloudy and viscous, which hinders filtration, decreases yield, and causes the loss of quality after its processing and during storage. This study aimed to evaluate enzymatic treatment effects using crude multi-enzymatic extracts (CME) obtained from Rhodotorula mucilaginosa, Rhodotorula orizycola, and Pseudozyma sp. produced by submerse fermentation in the extraction of juice guava. Mixtures of 100 ml of guava pulp and multi-enzymatic extracts proposed by Doehlert planning were incubated under constant agitation at 150 rpm and 50°C, and a Doehlert design was applied as a multivariate optimization strategy. The optimal conditions using the multi-enzymatic extract were: 0.4% (v/v) of CME for 131 min for the multi-enzymatic treatment using Pseudozyma sp.; 3.0% (v/v) of CME for 154 min using the R. mucilaginosa CME; and 5.0% (v/v) of CME for 90 min using R. oryzicola. The maximum viscosity reduction values for the juices treated with the CME of yeasts were 10.33%, 86.38%, and 13.33% for the juices treated with the CME of Pseudozyma sp., R. mucilaginosa, and R. orizycola, respectively. The physical-chemical properties were improved after treatment with CMEs, yielding a reduction of clarity, increase of total soluble solids and reducing sugars, and decreasing the acidity (pH) for all treatments with enzymatic extracts of all strains. The yeasts studied showed a potential for CME production to be applied to juice, improving the quality of the juice, and R. mucilaginosa was the most prominent yeast due to most significant reduction of viscosity in guava juice.

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.

Chemical constituents from the leaves of psidium guajava linn. and their chemotaxonomic significance.

The phytochemical investigation on the leaves of Psidium guajava Linn. led to the isolation and identification of 18 compounds, including six guavinoside (1-6), four flavonoids (7-10), eight triterpenoids (11-17) and one lignans (18). All chemical structures were elucidated via NMR spectroscopic methods, and further supported by comparison with literature data. Compounds 12, 14, 16 and 18 was isolated from the Myrtaceae family for the first time. The chemotaxonomic significance of these compounds was also discussed based on their structure types, as well as compounds-genus/family network analysis. The results showed that there were close chemotaxonomic relationships among the Myrtaceae, Asteraceae, and Lamiaceae families. Guavinosides A-F could be considered as valuable chemotaxonomic markers of Myrtaceae family, while guavinosides C-F might serve as chemotaxonomic markers for distinguishing the P. guajava.

Phytochemical profiling, antidiabetic, antitumoral and cytotoxic potential of Psidium cattleianum Afzel. ex Sabine leaves of red variety.

In this study, phytochemical profiling, and antidiabetic, antitumoral and cytotoxic potential of aqueous extracts of leaves of red variety of Psidium cattleianum Afzel. ex Sabine were investigated. The extracts were obtained using a cellulase complex. The total phenolic compounds (TPC) were determined, and the individual phenolic compounds were quantified by HPLC-ESI-MS/MS. For the TPC, the amounts varied from 85.91 to 106.33 mg EAG g-1. Eighteen compounds have been identified. The compounds with the highest concentrations were gallic acid, quercetin and protocatechuic acid. Antidiabetic activity was obtained through α-amylase and α-glucosidase inhibition tests. The extract inhibited 17.94% of α-amylase activity and 73.34% of α-glucosidase activity. The antitumoral activity in cells of cutaneous melanoma (SK-MEL-28) and the cytotoxic activity was determined in peripheral blood mononuclear cells (PBMC). The cellular migration was determined for cells SK-MEL-28. Antitumoral effects on cells SK-MEL-28 were observed and the absence of cytotoxicity on the PBMCs.

Investigation of the chemical composition of antibacterial Psidium guajava extract and partitions against foodborne pathogens.

P. guajava was partitioned into aqueous and ethyl acetate fractions and studied for its antibacterial chemical constituents. The minimum inhibitory concentrations of the aqueous and ethyl acetate partitions against Escherichia coli, Salmonella Typhimurium, and Staphylococcus aureus were found to be 0.75, 0.75, 0.15, 0.5, 0.5, and 0.125%, respectively. Using LC-MS-based chemical fingerprinting, auto MS/MS fragmentation and bioactive molecular networking, 18 compounds of interest were detected. The top 10 bioactive compounds and eight additional non-bioactive compounds known to be found in P. guajava are highlighted. We report five compounds to be identified in P. guajava for the first time. Studies have indicated P. guajava to be a plant source of antibacterial compounds that could be useful in the food industry to prevent foodborne illnesses outbreaks, reduce food spoilage, and satisfy consumer demands for less synthetic chemical usage in the food industry.

Major chemical carcinogens and health exposure risks in some therapeutic herbal plants in Nigeria.

People of all ages and genders utilize herbal medicine to treat varieties of problems all around the world. The accumulation of Cd and Cr in therapeutic herbs (Adansonia digitata, Psidium guajava, and Carica papaya) can lead to a variety of health complications. These leaf extracts are used to treat varieties of ailments, including cancer, in the northern Nigerian states of Borno, Jigawa, and Kano. The researchers employed high-resolution continuous source atomic absorption spectrometry. The statistical parameters such as mean, range, minimum and maximum were computed along with one-way analysis of variance (ANOVA) to assess activity concentrations of Major Chemical Carcinogens (MCCs) in the herb extracts from the three states. The result demonstrated substantial statistical variation in the concentration of Chromium between groups with C. papaya (F = 190.683, p = 0.000), P. guajava (F = 5.698, p = 0.006), A. digitata (F = 243.154, p = 0.000). The post hoc test revealed that the C. papaya and A. digitata observed concentrations were statistically significant across the three states (p = 0.000). It was observed that there is no statistically significant difference between concentrations of the extracts between Kano and Borno states for P. guajava (p = 0.686). For Cd, the one-way ANOVA showed significant statistically variation in the concentration between groups with C. papaya (F = 77.393, p = 0.000), P. guajava (F = 4.496, p = 0.017), A. digitata (F = 69.042, p = 0.000). The post hoc test with multiple comparisons revealed that the activity concentration of all extracts was statistically significant across the three states (p<0.05). The target risk quotient (THQ) for Cd was more than unity in A. digitata and C. papaya, except for P. guajava from Borno State. The probable cancer risk was observed for consumption of plant extracts as a result of Cr and Cd.

Psidium guajava L. An Incalculable but Underexplored Food Crop: Its Phytochemistry, Ethnopharmacology, and Industrial Applications.

Psidium guajava L. (guava) is a small tree known for its fruit flavor that is cultivated almost around the globe in tropical areas. Its fruit is amazingly rich in antioxidants, vitamin C, potassium, and dietary fiber. In different parts of the world, this plant holds a special place with respect to fruit and nutritional items. Pharmacological research has shown that this plant has more potential than just a fruit source; it also has beneficial effects against a variety of chronic diseases due to its rich nutritional and phytochemical profile. The primary goal of this document is to provide an updated overview of Psidium guajava L. and its bioactive secondary metabolites, as well as their availability for further study, with a focus on the health benefits and potential industrial applications. There have been several studies conducted on Psidium guajava L. in relation to its use in the pharmaceutical industry. However, its clinical efficacy and applications are still debatable. Therefore, in this review a detailed study with respect to phytochemistry of the plant through modern instruments such as GC and LC-MS has been discussed. The biological activities of secondary metabolites isolated from this plant have been extensively discussed. In order to perform long-term clinical trials to learn more about their effectiveness as drugs and applications for various health benefits, a structure activity relationship has been established. Based on the literature, it is concluded that this plant has a wide variety of biopharmaceutical applications. As a whole, this article calls for long-term clinical trials to obtain a greater understanding of how it can be used to treat different diseases.

Green Synthesis and Characterization of Cobalt Oxide Nanoparticles Using Psidium guajava Leaves Extracts and Their Photocatalytic and Biological Activities.

The advanced technology for synthesizing nanoparticles utilizes natural resources in an environmentally friendly manner. Additionally, green synthesis is preferred to chemical and physical synthesis because it takes less time and effort. The green synthesis of cobalt oxide nanoparticles has recently risen due to its physico-chemical properties. In this study, many functional groups present in Psidium guajava leaf extracts are used to stabilize the synthesis of cobalt oxide nanoparticles. The biosynthesized cobalt oxide nanoparticles were investigated using UV-visible spectroscopic analysis. Additionally, Fourier-transform infrared spectroscopy revealed the presence of carboxylic acids, hydroxyl groups, aromatic amines, alcohols and phenolic groups. The X-ray diffraction analysis showed various peaks ranging from 32.35 to 67.35°, and the highest intensity showed at 36.69°. The particle size ranged from 26 to 40 nm and confirmed the average particle size is 30.9 nm. The green synthesized P. guajava cobalt oxide nanoparticles contain cobalt as the major abundant element, with 42.26 wt% and 18.75 at% confirmed by the EDAX techniques. SEM images of green synthesized P. guajava cobalt oxide nanoparticles showed agglomerated and non-uniform spherical particles. The anti-bacterial activity of green synthesized P. guajava cobalt oxide nanoparticles was evaluated against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli with a 7 to 18 mm inhibitory zone. The photocatalytic activity was evaluated using green synthesized P. guajava cobalt oxide nanoparticles and observed 79% of dye degradation. The MTT assay of P. guajava cobalt oxide nanoparticles showed an excellent cytotoxic effect against MCF 7 and HCT 116 cells compared to normal cells. The percentage of cell viability of P. guajava cobalt oxide nanoparticles was observed as 90, 83, 77, 68, 61, 58 and 52% for MCF-7 cells and 82, 70, 63, 51, 43, 40, and 37% for HCT 116 cells at the concentration of 1.53, 3.06, 6.12, 12.24, 24.48, 50, and 100 µg/mL compared to control cells. These results confirmed that green synthesized P. guajava cobalt oxide nanoparticles have a potential photocatalytic and anti-bacterial activity and also reduced cell viability against MCF-7 breast cancer and HCT 116 colorectal cancer cells.

The effect of Psidium guajava hydroalcoholic extract on reducing the expression of Resistin and TNF-α genes in articular chondrocytes of patients with knee osteoarthritis.

Knee osteoarthritis is the most common joint disease and the most important cause of disability in elderly patients. Due to the side effects of nonsteroidal anti-inflammatory drugs (NSAIDs) in the treatment of osteoarthritis, the use of herbs is recommended as an alternative treatment. The guava fruit can be considered as a natural medicine due to its antioxidant and anti-inflammatory properties. In this study, the effect of Psidium guajava hydroalcoholic extract was considered on reducing the expression of the resistin gene and TNF-α gene in articular chondrocytes of patients with knee osteoarthritis. For this purpose, cartilage chondrocytes of 10 Chinese patients with knee osteoarthritis, who were indicated for arthroplasty, were used for evaluating the effect of guava fruit on the expression of these genes. Articular chondrocytes were cultured under appropriate conditions and their viability was assessed by MTT assay. To increase the level of cytokines, cells were treated with lipopolysaccharide (LPS). They were kept in an incubator with 90% humidity at 37°C for the next steps. Then, the expression of the resistin gene and TNF-α gene was investigated by RNA isolation and cDNA preparation. The results showed that the expression of the resistin gene and TNF-α gene were reduced to 56.59% and 51.86%, respectively, by hydroalcoholic extract of guava fruit. Therefore, according to the results of this study and previous researches, the hydroalcoholic extract of guava fruit (Psidium guajava) can be considered as an effective complementary and alternative treatment for osteoarthritis of the knee.

Antidiabetic effects of Psidium x durbanensis Baijnath & Ramcharun ined. (Myrtaceae) leaf extract on streptozotocin-induced diabetes in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Psidium guajava L. leaves are used to treat diabetes in South African folkloric medicine and in other parts of the world. Psidium x durbanensis Baijnath & Ramcharun ined. (PD) is a natural sterile hybrid and congener of Psidium guajava that is expected to share the medicinal properties of the genus Psidium and is widely distributed in South Africa. AIM OF THE STUDY: This study investigates the antioxidant, antidiabetic effects, and mechanisms of action of hydro-methanolic leaf extracts of PD on streptozotocin-induced diabetes in rats. MATERIAL AND METHODS: Phytochemical constituents of hydro-methanolic extract of PD were analyzed by gas chromatography-mass spectrometry (GC-MS). Male Wistar rats 250-300 g body weight (BW) were rendered diabetic after a single intraperitoneal injection with streptozotocin, 45 mg/kg BW. The diabetic rats were treated with hydro-methanolic (20:80 v/v) leaf extracts of PD (400 mg/kg/BW) or subcutaneous injections of regular insulin (2.0U/kg/BW, bid) for 56 days. The body weights of the animals were recorded daily. Fasting blood glucose, glucose tolerance tests, and insulin resistance index were measured. The effects of the extracts on total superoxide dismutase, catalase, and reduced glutathione activities, histopathology, and gene expression of insulin receptor substrate 1 and glucose transporter 4 were determined in the liver, pancreas, and gastrocnemius muscles of the rats. RESULTS: In the acute toxicity studies, there were no signs of toxicity observed for PD up to 2000 mg/kg BW doses. Diabetic animals showed significant weight loss, elevated and reduced fasting blood glucose and insulin, respectively, impaired glucose tolerance and diminished antioxidant enzymes' activities compared to controls. Treatment with PD hydro-methanolic leaf extracts improved body weight, glucose tolerance, insulin resistance, and antioxidant enzymes but not plasma insulin in diabetic animals compared to controls, respectively. GC-MS analysis identified organic acids, alcohols, vitamins, terpenoids, and esters in the extracts. Treatment with PD improved glucose uptake by stimulating mRNA expression of GLUT 4 in gastrocnemius muscles of diabetic animals compared to the untreated control and also restored histological aberrations in the pancreas and liver of diabetic rats compared with the untreated control rats. CONCLUSION: Collectively, the present study suggests that treatment with PD leaf extracts significantly ameliorated diabetes symptoms and oxidative stress in rats, and these effects may be linked to the bioactive phytoconstituents present in the plant. This study further suggests that PD improves insulin resistance by increasing glucose uptake in gastrocnemius muscles in an insulin-independent manner.