In vitro antimicrobial activity of methanolic leaf extract of Psidium guajava L

GC-MS analysis and pharmacological potentiality of Lasia spinosa (L.) Thwaites leaves and fruit extracts: an in vitro and in silico studies

Lasia spinosa (L. spinosa) is widely used in Asian countries for treating various diseases and as a vegetable, yet its bioactive properties remain under-researched. It is traditionally utilized in Ayurveda and the AYUSH system of medicine for its medicinal properties, and commonly used to treat digestive disorders, respiratory issues, and inflammatory conditions. This study aims to identify the phytochemicals in L. spinosa leaves and fruit extracts and evaluate their biological activities. Phytochemicals in methanol extracts of L. spinosa fruits and leaves were identified by GC-MS analysis. Antioxidant and cytotoxic activities were assessed using the DPPH free radical and nitric oxide (NO) scavenging assay and brine shrimp lethality test. Antibacterial activity was evaluated against Shigella boydii, Shigella flexneri, Streptococcus iniae, and Streptococcus dysgalactiae, while antifungal properties were tested against Cercospora beticola and Rhizoctonia solani. Molecular docking was conducted to predict the effectiveness of L. spinosa phytochemicals against NADPH oxidase and the Shigella effector OspG. Nine compounds were detected from both extracts. The methanol leaves extract exhibited superior antioxidant activity compared to the fruit extract, with IC50 values of 111.81 ± 8.99 µg/ml and 174.81 ± 4.86 µg/ml, respectively, as determined by the DPPH scavenging assay. The nitric oxide (NO) scavenging assay also revealed higher potency in the leaves extract (IC50 = 138.59 ± 1.50 µg/ml) compared to the fruit extract (IC50 = 196.47 ± 1.72 µg/ml). Both extracts showed significant antimicrobial activity against all tested microorganisms. In silico studies indicated notable inhibitory activity of all phytochemicals against the target proteins, with Linoelaidic acid and 9-Octadecenamide, (Z)- exhibiting the highest activity against NADPH oxidase (PDB: 2cdu) and Shigella flexneri OspG effector kinase (PDB: 4bvu), respectively. These findings suggest that L. spinosa has potent antioxidant and antimicrobial activities. Compounds from this plant could serve as lead compounds for developing antioxidant and antibacterial agents. However, molecular studies should be addressed.

Herbal medicine: the magic way crouching microbial resistance

Bacterial resistance to antibiotics poses a high level of danger worldwide. Bacterial resistance mechanisms are spreading globally, impeding our ability to treat common infectious diseases. Misuse and overuse of antibiotics accelerate microbial resistance to antibiotics. Despite the exerted efforts, none of the newly developed antibiotics are expected to be effective against the dangerous forms of antibiotic-resistant bacteria. Since many plants have been shown to contain powerful antimicrobial compounds that can act synergistically or alternatively to antibiotics, the demand for herbal medicines has recently increased to co-treat microbes that are resistant to antibiotics. Maximum benefit can be achieved when the pharmacokinetics and pharmacodynamics of natural products match the antibiotic. This review article refers to nine highly effective and key herbs to use alongside antibiotics to overcome crises of antibiotic resistance. Their unique molecular mechanisms of action have been highlighted.

Enhancement of the Functional Performance of Cotton and Polyester Fabrics upon Treatment with Polymeric Materials Having Different Functional Groups in the Presence of Different Metal Nanoparticles

This work examined the functional properties of three different treated fabrics, cotton, polyester, and cotton/polyester, with different polymeric materials (polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), or chitosan) in the presence and absence of two synthesized metal nanoparticles to impart and enhance fabric properties. Both metal nanoparticles (silver nanoparticle (AgNPs) and Zinc oxide nanoparticles (ZnONPs)) were synthesized using Psidium guajava Leaves and characterized using different techniques. The different treated fabrics were dyed with Reactive Dye (Syozol red k-3BS) and evaluated for their color strength, fastness properties, ultraviolet protection, antimicrobial activity, and mechanical properties. Results showed that treatment with polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), or chitosan enhances the functionality of all fabrics, with improved color strength, UV protection, and antimicrobial properties. Additionally, mechanical properties were slightly increased due to the creation of a thin film on the fabric surface. All dyed treated fabrics showed good ultraviolet protection and antimicrobial properties. The K/S of all treated textiles including nanoparticles and polymers was marginally greater than that of the treated materials without polymers. The UPF values demonstrate that the three investigated polymers and both metal nanoparticles enhance the fabrics' ability to block UV radiation and shield people's skin from its damaging effects. All treated textiles had UPF values that are higher than those of untreated textiles. Further research demonstrates that ZnONP-treated textiles exhibited greater UPF values than AgNP-treated textiles when the polymer component was present. Antibacterial examination demonstrated that treated materials had robust microbial resistance. This resistance is diminished by washing, but still prevents bacterial growth more effectively than untreated textiles.

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.

Effect of altitude and solvent on Psidium guajava Linn. leaves extracts: phytochemical analysis, antioxidant, cytotoxicity and antimicrobial activity against food spoilage microbes

BACKGROUND

Guava (Psidium guajava Linn.) has been traditionally used in the treatment of a wide range of diseases due to its rich content of secondary metabolites.

AIM

This study was aimed to evaluate the effect of altitude and solvent systems on guava leaves crude extract's phenolics and flavonoid content, antioxidant, antimicrobial, and toxicity nature.

METHODS

Guava leaves were collected from three different geographical locations in Nepal while solvents with an increasing polarity index were used for extraction. The yield percentage of extracts was calculated. Total Phenolic Content, Total Flavonoid Content, and antioxidant activity were determined by the Folin-Ciocalteu method, Aluminium chloride colorimetric method, and DPPH (2,2'-Diphenyl-1-picrylhydrazyl) assay respectively. The quantification of fisetin and quercetin was performed using the HPLC with method validation. The antimicrobial activity of the extracts was tested against bacteria and fungus isolated from spoiled fruits and vegetables and identified through 16s and 18s rRNA sequencing. Finally, Brine Shrimp Lethality Assay (BSLA) was used for testing the toxicity of the extracts.

RESULTS

The phenolic and total flavonoid content was found to be higher in ethanol extract (331.84 mg GAE/g dry extract) and methanol extract (95.53 mg QE/g dry extract) from Kuleshwor respectively. Water extract of guava leaves from Kuleshwor (WGK) did not show significantly different antioxidant activity when compared to methanol and ethanol extracts. Fisetin and quercetin were higher in WGK (1.176 mg/100 g) and (10.967 mg/100 g) dry extract weight respectively. Antibacterial activity against food spoilage bacteria was dose-dependent and found to be highest for all the extracts from different solvents and altitudes at higher concentrations (80 mg/ml). Similarly, methanol and ethanol guava extracts from all locations showed antifungal activity against Geotrichum candidum RIBB-SCM43 and Geotrichum candidum RIBB-SCM44. WGK was found to be non-toxic.

CONCLUSION

Our study concludes that the antioxidant and antimicrobial activity of WGK was found to be similar statistically to that of methanol and ethanol extracts of Bishnupur Katti and Mahajidiya. These results suggest the possibility of using water as a sustainable solvent to extract natural antioxidant and antimicrobial compounds which can further be used as natural preservatives to extend the shelf life of fruits and vegetables.

Antimicrobial Biosynthetic Potential and Phylogenetic Analysis of Culturable Bacteria Associated with the Sponge Ophlitaspongia sp. from the Yellow Sea, China

Sponge-derived bacteria are considered to be a promising source of novel drugs, owing to their abundant secondary metabolites that have diverse biological activities. In this study, we explored the antimicrobial biosynthetic potential and phylogenetics of culturable bacteria associated with the sponge Ophlitaspongia sp. from the Yellow Sea, China. Using culture-dependent methods, we obtained 151 bacterial strains, which were then analysed for their antimicrobial activities against seven indicator strains. The results indicate that 94 (62.3%) of the 151 isolated strains exhibited antimicrobial activities and inhibited at least one of the indicator strains. Fifty-two strains were selected for further phylogenetic analysis using 16S rRNA gene sequencing, as well as for the presence of polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS) genes. These 52 strains belonged to 20 genera from 18 families in 4 phyla, including Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. Five strains with PKS genes and ten strains with NRPS genes were detected. Among them, two strains contained both PKS and NRPS genes. Notoacmeibacter sp. strain HMA008 (class Alphaproteobacteria) exhibited potent antimicrobial activity; thus, whole genome sequencing methods were used to analyse its secondary metabolite biosynthetic gene clusters. The genome of HMA008 contained 12 biosynthetic gene clusters that potentially encode secondary metabolites belonging to compound classes such as non-ribosomal peptides, prodigiosin, terpene, β-lactones, and siderophore, among others. This study indicates that the sponge Ophlitaspongia sp. harbours diverse bacterial strains with antimicrobial properties and may serve as a potential source of bioactive compounds.

An Annotated Inventory of Tanzanian Medicinal Plants Traditionally Used for the Treatment of Respiratory Bacterial Infections

This review comprehensively covers and analyzes scientific information on plants used in Tanzanian traditional medicine against respiratory diseases. It covers ethnobotanical and ethnopharmacological information extracted from SciFinder, Google Scholar, and Reaxys as well as the literature collected at the Institute of Traditional Medicine in Dar-es-Salaam. Crude extracts and fractions of 133 plant species have literature reports on antimicrobial bioassays. Of these, 16 plant species had a minimum inhibitory activity of MIC ≤ 50 µg/mL. Structurally diverse compounds were reported for 49 plant species, of which 7 had constituents with MIC ≤ 5 µg/mL against various bacteria: Bryophyllum pinnatum (Lam.) Oken, Warburgia ugandensis Sprague, Diospyros mespiliformis Hochst. ex DC., Cassia abbreviata Oliv., Entada abyssinica A. Rich., Strychnos spinosa Lam., and Milicia excelsa (Welw.) C.C. Berg. The low number of antimicrobial active extracts and compounds suggests that antibacterial and antimycobacterial drug discovery needs to have a fresh look at ethnobotanical information, diverting from too reductionist an approach and better taking into account that the descriptions of symptoms and concepts of underlying diseases are different in traditional African and modern Western medicine. Nevertheless, some structurally diverse compounds found in anti-infective plants are highlighted in this review as worthy of detailed study and chemical modification.

Kinetic and Thermodynamic Study of Plantaricin IIA-1A5, a Bacteriocin Produced by Indonesian Probiotic Lactobacillus plantarum IIA-1A5

BACKGROUND

Plantaricin IIA-1A5 is a bacteriocin produced by Lactobacillus plantarum IIA-1A5, a locally isolated probiotic from Indonesia. Plantaricin IIA-1A5 exhibits antibacterial activity against wide spectrum of pathogenic bacteria, thus promising to be applied in various food products. Nevertheless, thermal stability of this bacteriocin remains to be fully investigated.

OBJECTIVE

This study aims to determine thermal stability of plantaricin IIA-1A5 through kinetic and thermodynamic parameters.

METHOD

To address, plantaricin IIA-1A5 was purified from Lactobacillus plantarum IIA-1A5, which was growth under whey media, using ammonium sulfate precipitation followed by ionexchange chromatography. Purified plantaricin IIA-IA5 was then subjected to analysis of its bacteriocin activity. The thermal inactivation of bacteriocin from L. plantarum IIA-1A5 was calculated by incubating the bacteriocin at different temperatures ranging from 60-80 °C for 30 to 90 min, which was then used to calculate its kinetic and thermodynamic parameters.

RESULTS

The result showed the inactivation rates (k-value) were ranging from 0.008 to 0.013 min-1. Heat resistance of plantaricin IIA-1A5 (D-value) at constant heating temperature of 60, 65, 70, 75, and 80 °C were 311.6, 305.9, 294.5, 198.9, and 180.2 min, which indicated a faster inactivation at higher temperatures. D-value sensitivity for temperature changes (z-value) was calculated to be 75.76 °C. Further, thermodynamic analysis suggested that plantaricin IIA-1A5 is thermostable, with activation energy (Ea) of 29.02 kJ mol-1.

CONCLUSION

This result showed that plantaricin IIA-1A5 is considerably more heat-stable than plantaricin members and promises to be applied in food industries where heat treatments are applied. Furthermore, a possible mechanism by which plantaricin IIA-1A5 maintains its stability was also discussed by referring to its thermodynamic parameters.

Chemical constituents of Psidium guajava leaves and their antibacterial activity

Seven undescribed compounds, namely (+)-psiflavanone A, (-)-psiflavanone A, (+)-psiflavanone B, (-)-psiflavanone B, (+)-psiketide, (-)-psiketide, and psidinone, were isolated and chirally separated from the 95%-ethanol extract of Psidium guajava leaves. (+)/(-)-Psiflavanone A and (+)/(-)-psiflavanone B are two pairs of rare enantiomeric C-benzoylated flavanones isolated from the title plant for the first time. (+)/(-)-Psiketide are a pair of enantiomeric aromatic polyketides, and psidinone is the first example of a C₁₈ phenanthrenediquinone with an angle-type 6/6/6 tricyclic skeleton. Their structures were identified by extensive analysis of HRESIMS, UV, IR, NMR, and calculated electronic circular dichroism (ECD) data. Particularly, the structures of (+)-psiflavanone A, (-)-psiflavanone A, (+)-psiflavanone B, and psidinone were further confirmed by X-ray diffraction. Psidinone exhibited antibacterial activity against Staphylococcus aureus, Staphylococcus epidermidis, and Mycobacterium Smegmatis mc² 155, with minimum inhibitory concentrations (MICs) of 16, 8, and 0.5 μM, respectively. These results not only highlight the chemical diversity and biological activity of P. guajava but are also expected to pave way for its further expansion to other applications in future.

Guava (Psidium guajava L.) Leaves: Nutritional Composition, Phytochemical Profile, and Health-Promoting Bioactivities

Psidium guajava (L.) belongs to the Myrtaceae family and it is an important fruit in tropical areas like India, Indonesia, Pakistan, Bangladesh, and South America. The leaves of the guava plant have been studied for their health benefits which are attributed to their plethora of phytochemicals, such as quercetin, avicularin, apigenin, guaijaverin, kaempferol, hyperin, myricetin, gallic acid, catechin, epicatechin, chlorogenic acid, epigallocatechin gallate, and caffeic acid. Extracts from guava leaves (GLs) have been studied for their biological activities, including anticancer, antidiabetic, antioxidant, antidiarrheal, antimicrobial, lipid-lowering, and hepatoprotection activities. In the present review, we comprehensively present the nutritional profile and phytochemical profile of GLs. Further, various bioactivities of the GL extracts are also discussed critically. Considering the phytochemical profile and beneficial effects of GLs, they can potentially be used as an ingredient in the development of functional foods and pharmaceuticals. More detailed clinical trials need to be conducted to establish the efficacy of the GL extracts.

Health Effects of Psidium guajava L. Leaves: An Overview of the Last Decade

Today, there is increasing interest in discovering new bioactive compounds derived from ethnomedicine. Preparations of guava (Psidium guajava L.) leaves have traditionally been used to manage several diseases. The pharmacological research in vitro as well as in vivo has been widely used to demonstrate the potential of the extracts from the leaves for the co-treatment of different ailments with high prevalence worldwide, upholding the traditional medicine in cases such as diabetes mellitus, cardiovascular diseases, cancer, and parasitic infections. Moreover, the biological activity has been attributed to the bioactive composition of the leaves, to some specific phytochemical subclasses, or even to individual compounds. Phenolic compounds in guava leaves have been credited with regulating blood-glucose levels. Thus, the aim of the present review was to compile results from in vitro and in vivo studies carried out with guava leaves over the last decade, relating the effects to their clinical applications in order to focus further research for finding individual bioactive compounds. Some food applications (guava tea and supplementary feed for aquaculture) and some clinical, in vitro, and in vivo outcomes are also included.

The effects of Nigella sativa (Ns), Anthemis hyalina (Ah) and Citrus sinensis (Cs) extracts on the replication of coronavirus and the expression of TRP genes family

Extracts of Anthemis hyalina (Ah), Nigella sativa (Ns) and peels of Citrus sinensis (Cs) have been used as folk medicine to fight antimicrobial diseases. To evaluate the effect of extracts of Ah, Ns and Cs on the replication of coronavirus (CoV) and on the expression of TRP genes during coronavirus infection, HeLa-CEACAM1a (HeLa-epithelial carcinoembryonic antigen-related cell adhesion molecule 1a) cells were inoculated with MHV-A59 (mouse hepatitis virus–A59) at moi of 30. 1/50 dilution of the extracts was found to be the safe active dose. ELISA kits were used to detect the human IL-8 levels. Total RNA was isolated from the infected cells and cDNA was synthesized. Fluidigm Dynamic Array nanofluidic chip 96.96 was used to analyze the mRNA expression of 21 TRP genes and two control genes. Data was analyzed using the BioMark digital array software. Determinations of relative gene expression values were carried out by using the 2^−∆∆Ct method (normalized threshold cycle (Ct) value of sample minus normalized Ct value of control). TCID₅₀/ml (tissue culture infectious dose that will produce cytopathic effect in 50 % of the inoculated tissue culture cells) was found for treatments to determine the viral loads. The inflammatory cytokine IL-8 level was found to increase for both 24 and 48 h time points following Ns extract treatment. TRPA1, TRPC4, TRPM6, TRPM7, TRPM8 and TRPV4 were the genes which expression levels changed significantly after Ah, Ns or Cs extract treatments. The virus load decreased when any of the Ah, Ns or Cs extracts was added to the CoV infected cells with Ah extract treatment leading to undetectable virus load for both 6 and 8hpi. Although all the extract treatments had an effect on IL-8 secretion, TRP gene expression and virus load after CoV infection, it was the Ah extract treatment that showed the biggest difference in virus load. Therefore Ah extract is the best candidate in our hands that contains potential treatment molecule(s).

Antimicrobial and free radical scavenging activities of five Palestinian medicinal plants

Extracts from five indigenous Palestinian medicinal plants including Rosmarinus officinalis, Pisidium guajava, Punica granatum peel, grape seeds and Teucrium polium were investigated for antimicrobial and free radical scavenging activities against eight microorganisms, using well diffusion method. The microorganisms included six bacterial isolates (i.e. Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginos, Klebsiella pneumonia, Bacillus subtilis and Micrococcus luteus) and two fungal isolates (i.e. Candida albicans and Aspergillus niger). A standard antioxidant assay was performed on the plant extracts to assess their capability in scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH). Of the five tested plant extract, only Rosmarinus offcinalis extract contained significant antimicrobial activity against all eight microbial isolates including Pseudomonas aeruginosa. Extracts from other four plants exhibited a variable antimicrobial activity against all microorganisms, except Pseudomonas aeruginosa. Significant antioxidant activity was detected in all plant extracts. However, extracts from Pisidium guajava leaves contained significantly higher antioxidant activity compared to the other extracts tested. The antimicrobial and scavenging activities detected in this in vitro study in extracts from the five Palestinian medicinal plants suggest that further study is needed to identify active compounds to target diseases caused by a wide-spectrum pathogens.

Interactions of extracts from selected chewing stick sources with Aggregatibacter actinomycetemcomitans

Background

Aggregatibacter actinomycetemcomitans produces a leukotoxin that activates a pro-inflammatory death of human monocytes/macrophages. A specific clone of this bacterium (JP2) has a 530-base pair deletion in the leukotoxin promoter gene and significantly enhanced expression of leukotoxin. This specific clone of A. actinomycetemcomitans is common in some African populations and has a strong association with periodontal attachment loss in adolescents in these populations. Chewing sticks of plant origin are commonly used as oral hygiene tool in Africa, but their role as a therapeutic agent in periodontal disease is poorly investigated.

Results

Ethanol extracts were made from 7 common plants used as chewing sticks in West-Africa. None of the tested extracts inhibited growth of A. actinomycetemcomitans. However, extracts from Psidium guajava (Guava) completely neutralized the cell death and pro-inflammatory response of human leukocytes induced by the leukotoxin. None of the six other tested chewing stick extracts showed this effect.

Conclusions

The discovery that extracts from Guava efficiently neutralizes A. actinomycetemcomitans leukotoxicity might lead to novel therapeutic agents and strategies for prevention and treatment of aggressive forms of periodontitis induced by infections with the highly leukotoxic JP2 clone of this bacterium.