Callistemon Citrinus Research Articles

Evaluation of urban air pollution by metal contents of woody vegetation leaves in the urban ecosystem

Urban air pollution is a major environmental concern, and it should be addressed on a priority basis for human health and the urban ecosystem. The study was performed to investigate and understand the spatial distribution and contamination levels in the leaves of selected plants (Eugenia jambolana, Morus alba, Dalbergia sissoo, Populus deltoides, Ficus religiosa, Ficus variegata, Cassia fistula, Eucalyptus camaldulensis, Melia azedarach, Psidium guajava, Pongamia pinnata, Callistemon citrinus, and Polyalthia longifolia) exposed to the polluted areas of Canal Road, Lahore. Metal concentrations (Pb, As, Cr, and Cd) in the leaves of the plants were analyzed using atomic absorption spectrometry (AAS). The contamination level of As (Average ~1.03 mg/kg) was found to be moderately low in all trees tested except in Eucalyptus camaldulensis (As~2.11 mg/kg). Lead (Pb) accumulation levels in the leaves were observed to be visibly higher in almost all samples (Average ~ 5.34 mg/kg) than the WHO recommended limit (2 mg/kg). Among all samples, Ficus religiosa was found to have the highest levels of Pb. The contamination trends of Cr were observed to be high (Average~1.06 mg/kg) in non-native species, specifically in Eucalyptus camaldulensis (3.21 mg/kg). The Cd concentrations were also found to be higher in all plant samples (Average ~1.90 mg/kg) than the WHO permissible limit (0.02 mg/kg) in plants. Principal Component Analysis (PCA), GIS, and Minitab-19 were also applied to the data. This work is important to set a baseline for future researchers to appraise pollution load in different areas in light of the findings of this study.

Role of Callistemon citrinus Leaf Phytosomes Against Oxidative Stress and Inflammation in Rats Fed with a High-Fat-Fructose Diet.

Phytosomes are used as vehicles that carry plant extracts. They exhibit biological activities and possess better bioavailability, bioabsorption, and lower toxicity than drugs. Obesity is an inflammatory state in which oxidative stress is present, which triggers severe effects on the body's organs. This study aimed to evaluate the impact of the extract and phytosomes of Callistemon citrinus on oxidative stress and inflammation in the liver and heart of Wistar rats fed with a high-fat-fructose diet. Phytosomes containing the extract of leaves of C. citrinus were prepared. The antioxidant, pro-inflammatory enzymes, and biomarkers of oxidative stress were evaluated. Among the groups, only the high-fat-fructose group presented an increase in the COX-2, 5-LOX, and MPO inflammatory enzymes, while the XO enzyme exhibited decreased activity. The groups were fed a hypercaloric diet for 15 weeks while orlistat, C. citrinus extract, and phytosomes were administered at three different concentrations, exhibiting enzyme activities similar to those of the control group. It was also observed that the lowest concentration of phytosomes had a comparable effect to the other concentrations. Callistemon citrinus extract can modulate the activities of enzymes involved in the inflammation process. Furthermore, small doses of phytosomes can serve as anti-inflammatory agents.

A pharmacological investigation for therapeutic potential of Callistemon citrinus as an anthelmintic agent (Bottle-Brush Plant)

The growing resistance of parasitic helminths to standard anthelmintic medications has sparked increased interest in exploring alternative treatments, particularly those derived from herbal sources. This research focuses on the anthelmintic properties of selected herbal plants, assessing their ability to inhibit and eliminate parasitic worms. Standard extraction techniques were employed to prepare various plant extracts, which were then tested using both in vitro and in vivo assays to determine their effectiveness. The findings revealed that several plant extracts showed significant anthelmintic effects, comparable to those of conventional medications. Phytochemical analysis identified a high concentration of alkaloids, tannins, saponins, and flavonoids, which are thought to be the primary contributors to the observed activity. These results indicate that these herbal plants may serve as promising natural anthelmintic agents, providing a sustainable and environmentally friendly alternative to synthetic drugs. Further research is necessary to isolate and identify the specific bioactive compounds, clarify their mechanisms of action, and assess their safety and efficacy in clinical applications. This study highlights the potential of herbal medicine in developing novel anthelmintic treatments and encourages the integration of traditional knowledge with modern scientific research.

Manufacture of Bioplastics Prepared from Chitosan Functionalized with Callistemon citrinus Extract.

The exploration of natural resources in bioplastics has advanced the development of bio-based materials. Utilizing the casting, chitosan (CH)-based films were manufactured with different glycerol (GLY) percentages (from 0 to 50% w/w of CH) and anthocyanin-enriched fractions (from 0 to 5% of w/w CH) of acidified ethanol extract of Callistemon citrinus flowers (CCE). Callistemon citrinus is an ornamental plant known for its bioactive compounds endowed with health benefits. The hydrocolloid films showed promising mechanical properties. The 30% GLY + 5% CCE film achieved an elongation at break of 57.4%, comparable to the 50% GLY film while possessing enhanced tensile strength and Young's modulus. The CCE, rich in antioxidants, acted as a plasticizer, improving films' flexibility and manageability. The films exhibit hydrophilic characteristics with moisture content and uptake values reflecting their water-absorbing capacity, while films with 30% GLY and 5% CCE exhibit enhanced hydrophobicity. In addition, CCE characterization reveals significant polyphenol content (734.45 mg GAE/g), highlighting its antioxidant capacity. Moreover, CCE supplies remarkable antioxidant properties to the films. These findings suggest the potential of these bioplastics for industrial applications as a sustainable solution to traditional plastics and in reducing environmental impact while preventing oxidative reactions in packaged products.

Novel Bioplastic Based on PVA Functionalized with Anthocyanins: Synthesis, Biochemical Properties and Food Applications.

Over the last ten years, researchers' efforts have aimed to replace the classic linear economy model with the circular economy model, favoring green chemical and industrial processes. From this point of view, biologically active molecules, coming from plants, flowers and biomass, are gaining considerable value. In this study, firstly we focus on the development of a green protocol to obtain the purification of anthocyanins from the flower of Callistemon citrinus, based on simulation and on response surface optimization methodology. After that, we utilize them to manufacture and add new properties to bioplastics belonging to class 3, based on modified polyvinyl alcohol (PVA) with increasing amounts from 0.10 to 1.00%. The new polymers are analyzed to monitor morphological changes, optical properties, mechanical properties and antioxidant and antimicrobial activities. Fourier transform infrared spectroscopy (FTIR) spectra of the new materials show the characteristic bands of the PVA alone and a modification of the band at around 1138 cm-1 and 1083 cm-1, showing an influence of the anthocyanins' addition on the sequence with crystalline and amorphous structures of the starting materials, as also shown by the results of the mechanical tests. These last showed an increase in thickening (from 29.92 μm to approx. 37 μm) and hydrophobicity with the concomitant increase in the added anthocyanins (change in wettability with water from 14° to 31°), decreasing the poor water/moisture resistance of PVA that decreases its strength and limits its application in food packaging, which makes the new materials ideal candidates for biodegradable packaging to extend the shelf-life of food. The functionalization also determines an increase in the opacity, from 2.46 to 3.42 T%/mm, the acquisition of antioxidant activity against 2,2-diphenyl-1-picrylhdrazyl and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) radicals and, in the ferric reducing power assay, the antimicrobial (bactericidal) activity against different Staphylococcus aureus strains at the maximum tested concentration (1.00% of anthocyanins). On the whole, functionalization with anthocyanins results in the acquisition of new properties, making it suitable for food packaging purposes, as highlighted by a food fresh-keeping test.

Enhancing bioactivity of Callistemon citrinus (Curtis) essential oil through novel nanoemulsion formulation

The main focus of this study was to create a stable and efficient nanoemulsion (NE) using Callistemon citrinus essential oil (EO). Various factors affecting the NE’s stability were optimized including oil %, Tween 80%, time of sonication, and its accelerated stability was examined. The research also considered the antibacterial, antifungal, and larvicidal effects of the optimized NE (B10). The optimum NE stood out for its stability, featuring a particle size of 33.15 ± 0.32 nm. Analysis via IR spectroscopy confirmed successful EO encapsulation in B10. The formulation remained stable for six months, with B10 showing significantly higher antibacterial and antifungal potency compared to the pure oil. When samples were subjected to tests against Fusarium oxysporum, B10 exhibited a MIC value of 62.5 mg/mL, whereas the pure oil showed a MIC value of 250 mg/mL. This indicates that the B10 formulation was 50 times more effective than the EO. In terms of antibacterial activity against Escherichia coli, the MIC value was 0.256 mg/mL for B10 and 4 mg/mL for the EO. Also, pure oil and B10 displayed larvicidal effects against Chilo suppressalis (Walker) larvae, with B10 eliminating 95.2% of larvae in 48 h. Overall, stable and optimum C. citrinus NE with its strong antimicrobial qualities, shows promise as an effective fungicide and insecticide.

Impact of Various IBA Concentrations on Rooting in Apical Shoot Cutting and Stem Cuttings of Callistemon lanceolatus (Sm.) Sweet in Polytunnel Conditions

The study was undertaken to identify the optimal concentration of IBA and type of cuttings suitable for propagation of Callistemon lanceolatus and it was conducted at the Vanavarayar Institute of Agriculture, Pollachi, Coimbatore, India from December 2022 to September 2023. The experiment addressed the challenges of seed propagation, such as their seed capsules need to be activated by fire and the unpredictable nature of seed germination, which results in high progeny diversity due to genetic recombination. The investigation focused on apical and stem cuttings subjected to fifteen different treatments with three replications each; the Tukey test was used for statistical analysis; the cuttings were treated with various concentrations of Indole-3-butyric acid (IBA) and placed under polytunnel conditions; observations were made after 45 days, measuring sprouting percentage, rooting percentage, mean number of leaves, shoot length, mean number of roots, and root length per cutting. In light of these issues, the study explored clonal propagation as an alternative for mass multiplication of elite trees. The results of the study depicted that the maximum rooting percentage and root length were observed in T6 (73.28±8.87%) and (12.54±0.00cm) due to the exogenous application of auxin. On the whole, the result of this investigation suggest that apical shoot cuttings with IBA at 6000ppm can be made to induce maximum rooting and to produce high quality planting stock material for clonal propagation in Callistemon lanceolatus.

Review on Callilstemon citrinus: Recent Approaches in Novel Drug Delivery System

Callistemon citrinus is an ornamental plant. The plant is commonly originated in subtropical and tropical region. C.citrinus, commonly referred to as bottlebrush, is a member of myrtaceae family. Active ingreadients such as 1, 8-cineole, triterpenoids, α-pinenes, eucalyptol, tannis, alkaloids, flavonoids, saponins, phytosterol etc. are mostly found in the various plant sections. It is generally use in traditional, folk and herbal medicine as a water accent, anticough, antibronchtits, insecticide and treatment of diarrhoea, dysentery and rheumatism. This article aims to provide a comprehensive review on the pharmacological aspects and recent novel approaches of callistemon citrinus highlight methodologies, applications, and potential contributions of this natural extract in enhancing drug delivery, offering insights into its pharmacological potential and future prospects in the field. The primary objective to collect updated information about effectiveness of the plant extract in addressing specific health issues and its potential as a therapeutic effect using novel drug delivery systems. Innovative methods explored in delivering the plant extract, such as Nano formulations in various diseases i.e. Antifungal properties, acute toxicity, brine shrimp cytotoxicity and relaxant activity, antimicrobial Activity etc. The methods improve therapeutic efficacy and reduces side effects by optimizing the delivery of bioactive compounds from callistemon citrinus. Keywords: Callistemon citrinus, Bottle brush, Pharmacological activities, Novel Drug Delivery Systems, Isolated compounds.

Comparative Study of Callistemon citrinus (Bottlebrush) and Punica granatum (Pomegranate) Extracts for Sustainable Synthesis of Silver Nanoparticles and Their Oral Antimicrobial Efficacy.

A comparative study was applied to investigate the potential of Callistemon citrinus (bottlebrush) flower extract (BBE) and Punica granatum (pomegranate) peel extracts (PPE) for the sustainable synthesis of the silver nanoparticles, Ag-BBE and Ag-PPE, respectively. The synthesis process of Ag NPs using the selected extracts was applied under optimized conditions. Hence, the effect of the selected plant's type on the different characteristics of the synthesized green Ag NPs was investigated. The UV-Vis spectroscopy revealed the presence of the characteristic silver peaks at 419 and 433 nm of the Ag-BBE and Ag-PPE, respectively. The XRD spectra reported the fcc phase formation of Ag NPs. The TEM results highlighted the morphological features of the synthesized Ag NPs. with a size range of 20-70 nm, and with 10-30 nm for Ag-BBE and Ag-PPE, correspondingly. The Raman spectra revealed characteristic silver bands in the Ag-PPE and reflected some bands related to the natural extract in the Ag-BBE sample. The antimicrobial activity and statistical analysis investigation were conducted against four selected oral pathogens (Staphylococcus aureus (SA), Candida albicans (CA), Staphylococcus epidermidis (S. epi), and Enterococcus faecalis (EF)). Both tested extracts, BBE, and PPE, revealed potential effectivity as reducing and capping agents for Ag NP green synthesis. However, the synthesized NPs demonstrated different features, depending on the used extract, reflecting the influence of the plant's biomolecules on the nanoparticles' properties.

Callistemon citrinus: A plant‐mediated synthesis of sustainable Rhodium nanoparticles and their antimicrobial activity

AbstractThis work investigates the potential of using Callistemon citrinu flower extract, commonly known as bottlebrush, in the environmentally friendly synthesis of Rhodium nanoparticles (Rh NPs). Callistemon citrinu flower extract contains a high concentration of flavonoids and other phytochemicals. Hence, the extract was used to provide the essential components for an environmentally, sustainable synthesis method of Rh NPs. Different characterization analyses were used to evaluate the different properties of the synthesized particles. UV spectroscopy analysis demonstrated a continuous UV absorption spectrum attributed to the formation of Rh NPs. The XRD data and SAED analysis showed an amorphous nature of the synthesized Rh NPs. The HRTEM imaging provided morphological information about the Rh NPs tested sample, where the efficiency of Callistemon citrinu flower extract as a capping agent was reported. Furthermore, Raman spectra displayed the characteristic vibrational bands of the synthesized Rh NPs. The antimicrobial activity of the synthesized samples was tested against several dental pathogens, that play a role in dental caries, Staphylococcus aureus (SA), Bacillus subtilis (BS), Candida albicans (CA), Escherichia coli (Eco), and Staphylococcus epidermidis (S. Epi). In comparison with the control, Chlorhexidine (CHX), Rh NPs showed a greater impact on C. albicans (20 ≤ Zone of inhibition (ZOI) (mm) ≤ 26). The statistical analysis demonstrated that Rh NPs had a greater mean ZOI than the Callistemon citrinu flower extract. These results reveal the considerable potential and biological capacity Rh NPs have as an antifungal agent for dental applications.

Biomonitoring with Lichens: Evaluating Heavy Metal Concentrations, Environmental Factors, and Lichen Diversity in Bengaluru, Karnataka, India

Lichens are commonly used in biomonitoring due to their unique characteristics that make them a cost-effective option. Unlike chemical analysis, sampling lichen diversity is less expensive, enabling a more extensive sampling coverage while reducing costs. This diverse group of organisms can be used to detect areas that are affected by pollution, land use changes, and ecological imbalances. In recent years, researchers have been working to establish a reliable protocol for lichen sampling in biomonitoring to enhance its utility and minimize any variations caused by extraneous environmental factors. In this article concentrations of heavy metals s (Cd, Cr, Cu, Fe, Ni, Pb and Zn), acidity and electrical conductance of few flowering trees bark (Albizialebbeck, Delonixregia, Pongamiaglabra, Callistemon Lanceolatus, Cassia Fistula, Cassia Javanica) were evaluated to determine the impact the lichen value diversity in six different places based on different environmental factors. It has been stated that the correlation between acidity level and lichen species exists in all investigated tree species. Six lichen species (Chrysothrixcandelaris (L.) Laundon, Graphisscripta (L.) Ach, G. scripta (L.) Ach., leucosorodes Nyl, D. consimilis (Stirton) Awasthi, D. aegialita (Afz. in Ach.) Moore and L.(perplexa Brodo) were registered, among them three were foliose and three were crutose. Lichen leucosorode Nyl was predominant in Albizialebbeck, Delonixregia, Pongamiaglabra trees. It was observed that the lichen diversity was less near heavy traffic location, industrial areas and also rougher bark of trees provided a better habitat of wider variety of lichen species.

Use of Callistemon citrinus as a gastroprotective and anti-inflammatory agent on indomethacin-induced gastric ulcers in obese rats.

Obesity leads to an elevated risk of developing gastrointestinal disease such as gastric ulcers. Callistemon citrinus leaf extract has shown antioxidant, antimicrobial, hepatoprotective, and chemoprotective effects against colon cancer. The aim of this study is to evaluate the gastroprotective effect of C. citrinus leaf extract on indomethacin-induced gastric ulcers in obese rats. Gastric ulcers were induced in female obese Wistar rats using a single oral dose of indomethacin (IND). In the first stage, the rats were fed with a high fat sugar diet (HFSD) for 15 weeks to induce obesity and, at the same time, the diet of the other group of animals included daily administration of ethanolic C. citrinus leaf extract (250 mg/kg) in addition to HFSD. In the second stage, gastric ulcers were induced with IND (30 mg/kg). The gastroprotective activity of C. citrinus, the inflammatory enzyme activities, and cytokines in the stomach were determined. C. citrinus produced a reduction of gastric lesions caused by IND. Myeloperoxidase (MPO), cyclooxygenase-2 (COX-2), and 5-lipoxygenase (5-LOX) activities also decreased. Although inflammatory biomarkers such as TNFα, IL-6, AOPP, and leptin were significantly decreased by C. citrinus, adiponectin levels increased. Moreover, C. citrinus decreased weight gain and morphological and biochemical parameters. The use of indomethacin in rats fed with a high fat-sugar diet increased gastric ulcers. Gastroprotective effect of C. citrinus in obese rats is attributed to the reduction of pro-inflammatory cytokines and the inflammatory enzymes.

Phytochemical Characterization of Callistemon lanceolatus Leaf Essential Oils and Their Application as Sustainable Stored Grain Protectants against Major Storage Insect Pests

Food storage has been important since the dawn of agriculture and human settlement. Insect pests cause major losses to food grains during storage and production. Essential oils are good alternatives for chemical insecticides for the management of storage pests. Red bottlebrush, Callistemon lanceolatus, is a flowering plant of the Myrtaceae family. This research work aimed to extract the oil from bottlebrush leaves, and chemically characterize and assess their repellent and insecticidal properties against the cowpea seed beetle, Callasobruchus maculatus (F.) (Coleoptera: Chrysomelidae), cigarette beetle, Lasioderma serricorne (F.) (Coleoptera: Ptinidae), and red flour beetle, Tribolium castaneum (Herbst.) (Coleoptera: Tenebrionidae), for the first time. The essential oil yielded by hydro-distillation of bottlebrush leaves was 1.02 ± 0.01%. GC-MS analysis determined the chemical composition of the volatile oil comprised 1,8-cineole (19.17%), α-terpineol (11.51%), α-pinene (10.28%), and α-Phellandrene (9.55%). The C. lanceolatus leaf oil showed potent repellence, contact toxicity, and fumigation toxic effects. In the contact toxicity assay, at 24 h, the LC50 values were 1.35, 0.52, and 0.58 mg/cm2 for the red flour beetle, cigarette beetle, and cowpea seed beetle, respectively. Likewise, in the fumigation assay observed after 24 h, LC50 values of 22.60, 5.48, and 1.43 µL/L air were demonstrated for the red flour beetle, cigarette beetle, and cowpea seed beetle, respectively. Additionally, there was no significance found by a phytotoxicity assay when the paddy seeds were exposed to C. lanceolatus oil. The results show that the volatile oils from red bottlebrush leaves have the potential to be applied as a biopesticide. Therefore, C. lanceolatus leaf oil can be utilized as a bio-insecticide to control stored product insects.

AAPH-induced oxidative damage reduced anion exchanger 1 (SLC4A1/AE1) activity in human red blood cells: protective effect of an anthocyanin-rich extract.

Introduction: During their lifespan in the bloodstream, red blood cells (RBCs) are exposed to multiple stressors, including increased oxidative stress, which can affect their morphology and function, thereby contributing to disease. Aim: This investigation aimed to explore the cellular and molecular mechanisms related to oxidative stress underlying anion exchanger 1 activity (band 3, SLC4A1/AE1) in human RBCs. To achieve this aim, the relationship between RBC morphology and functional and metabolic activity has been explored. Moreover, the potential protective effect of an anthocyanin-enriched fraction extracted from Callistemon citrinus flowers was studied. Methods: Cellular morphology, parameters of oxidative stress, as well as the anion exchange capability of band 3 have been analyzed in RBCs treated for 1h with 50mM of the pro-oxidant 2,2'-azobis (2-methylpropionamide)-dihydrochloride (AAPH). Before or after the oxidative insult, subsets of cells were exposed to 0.01μg/mL of an anthocyanin-enriched fraction for 1h. Results: Exposure to AAPH caused oxidative stress, exhaustion of reduced glutathione, and over-activation of the endogenous antioxidant machinery, resulting in morphological alterations of RBCs, specifically the formation of acanthocytes, increased lipid peroxidation and oxidation of proteins, as well as abnormal distribution and hyper-phosphorylation of band 3. Expected, oxidative stress was also associated with a decreased band 3 ion transport activity and an increase of oxidized haemoglobin, which led to abnormal clustering of band 3. Exposure of cells to the anthocyanin-enriched fraction prior to, but not after, oxidative stress efficiently counteracted oxidative stress-related alterations. Importantly, protection of band3 function from oxidative stress could only be achieved in intact cells and not in RBC ghosts. Conclusion: These findings contribute a) to clarify oxidative stress-related physiological and biochemical alterations in human RBCs, b) propose anthocyanins as natural antioxidants to neutralize oxidative stress-related modifications, and 3) suggest that cell integrity, and therefore a cytosolic component, is required to reverse oxidative stress-related pathophysiological derangements in human mature RBCs.

Comparative Studies of Essential Oil Composition and Biological Activities of Callistemon citrinus from Western Himalaya.

This work described a comprehensive study to estimate chemical constituents of essential oils (EOs) extracted from different parts of the Callistemon citrinus viz: fruits, leaves and aerial part. The EOs were characterized using physicochemical parameters, and GC-FID/MS. It was observed that among different parts, aerial part has the highest oil yield (0.90 %) followed by leaves and fruits. Further, seventeen compounds were characterized, and represented total amount (97.2-99.5 %) with domination of monoterpenes (12.5-34.6 %) and oxygenated monoterpenes hydrocarbon (61.8-86.8 %). α-pinene (11.8-24.7 %), α-phellandrene (1.2-3.0 %), p-cymene (3.3-3.9 %) and 1,8-cineole (58.3-85.1 %) were found as major compounds in C. citrinus samples. These major compounds are the quality chemical markers of C. citrinus oil. The findings revealed significant quantitative variations in EO composition of samples and were also clearly supported by multivariate statistical analysis. Moreover, EOs were evaluated for glucosidase and colon cancer cell lines inhibitory activities, which were found promising.

ORNAMENTAL PLANTS FOR ENVIRONMENTAL MANAGEMENT AT ROADSIDES IN KATHMANDU VALLEY, NEPAL

Plant species growing along roadsides in Kathmandu gives the development which is necessities of the good environment. This study determines plantation, coverage, leaves condition of important ornamental species at different sites of Kathmandu. Many Plant species are growing and applicable for bio-indicator and maintaining greenery. Bougainvillea glabra, Callistemon citrinus, Duranta erecta, Euphorbia pulcherrima, Jasminum mesnyi, Lagerstroemia indica, Malvaviscus penduliflorus, Nerium oleander and Rose indica are documented. The heavily polluted sites shows dominance of C. citrinus 73.33±2.08 and N. oleander has 73.7±1.6. The coverage of C. citrinus, D. erecta, J. mesnyi, L. indica and N. oleander has been observed as excellent along the roadside. However B. glabra, E. pulcherrima, M. penduliflorus and R. indica are seen at some places. These trees have the capacity to absorb carbon dioxide and reduce pollution levels. The study sites are heavily, moderately and less polluted sites. Plants in the period of study (2017 to 2022) from the observation and comparison are in further development. Elements analysis of soil and leaves are from ICP-OES (Inductively coupled plasma-optical emission spectrometry) were done. Subsequently, following elements Aluminium, Barilium, Cadmium, Cobalt, Chromium, Copper, Iron, Manganese, Nickel, Lead, Vanidium and Zinc were determined. The dust deposition on plants, chlorophyll content and anatomy of N. oleander was with less deposition of dust and chlorophyll values is increased (0.001547±0.000788 and 2.397±0.299). The stomata and stomatal index of C. citrinus are calculated (33.607± 4.509 and 15.699± 0.898). Evergreen and broad leaf trees have advantageous in environment. The summer in Kathmandu is gorgeous with L. indica flowers while flowers of C. citrinus and N. oleander observed in all seasons of the year. The success programs are recommended from the authority that is evaluated and continued for long term benefit.

Development and Evaluation of Phytosomes Containing Callistemon citrinus Leaf Extract: A Preclinical Approach for the Treatment of Obesity in a Rodent Model.

Callistemon citrinus has several biological effects; it is anti-inflammatory, anti-obesogenic, antioxidant, hepatoprotection, and chemoprotective. Its bioactive compounds include terpenoids, phenolic acids, and flavonoids which have low oral bioavailability and absorption. This study aimed at developing phytosomes of C. citrinus to improve oral bioavailability and absorption. Phytosomes were formulated with soybean phosphatidylcholine and C. citrinus leaf extract using the thin layer sonication method. Phytosomes were evaluated by scanning electron microscopy (SEM), entrapment efficiency, solubility, and particle size determination. Antioxidant capacity and total phenolic, flavonoid, and terpenoid contents were also measured. The in vivo anti-obesogenic activity was evaluated. Phytosomes loaded with C. citrinus (P C.c) extract had small spherical shapes. The average particle size was 129.98 ± 18.30 nm, encapsulation efficiency 80.49 ± 0.07%, and solubility 90.00%; the stability study presented no significant changes in the average particle size at 20 °C. P C.c presented high antioxidant capacity. For the first time, ellagic acid is reported in this plant. The in vivo obesity study showed a strong anti-obesogenic activity of phytosomes with C. citrinus to reduce 40% body weight as well as morphometric and biochemical parameters.

Plant Extracts Induced Resistance to Fusarium oxysporum f.sp. lycopersici in Tomato

Tomato (Lycopersicon esculentum Mill.) is the most consumed vegetable in the world after potato. In Cameroon, the plant is cultivated in almost all agroecological areas, however, yields remain low due to attacks by various pathogens and insects. Among the pathogens, Fusarium oxysporum f.sp. lycopersici (FOL) is a phytopathogenic fungus responsible for Fusarium wilt, a disease responsible for enormous economic losses. To contribute to the control of this microbial pathogen, the stimulatory effect of the tomato defence system of extracts of some plants in the tomato/FOL interaction was evaluated. Tomato plants were treated with the aqueous extracts (AE) of Callistemon citrinus (C. citrinus), Cymbopogon citratus (C. citratus), and Oxalis barrelieri (O. barrelieri ). After 4 days of spraying with the extracts, the plants were inoculated with a virulent strain of Fusarium oxysporum f.sp. lycopersici (FOL) under controlled conditions. Tomato roots were used to determine the contents of hydrogen peroxide (H2O2), phenols and malondialdehyde (MDA). The activities of the main antioxidant enzymes were also evaluated in tomato roots: catalase (CAT), phenylalanine ammonia lyase (PAL), peroxidase (POX) and superoxide dismutase (SOD). The results showed that treatment of tomato plants with plant extracts and their infection with FOL induced an increase in the contents of H2O2, phenols and MDA in tomato roots; an increase in PAL, POX, SOD activities and a reduction in CAT activity. Our results suggest that the increase and reduction of enzymatic activities, and the increase in the synthesis of some metabolites could mitigate the oxidative damage that takes place during the expansion of the pathogen. Aqueous extracts of C. citrinus, C. citratus and O. barrelieri at 10% (W/V) could be used as natural products to stimulate the tomato defence system against FOL. These results could contribute to the development of natural products to induce tomato resistance against FOL, thus improving productivity, quantity and quality of production.

Photocatalytic and biological properties of silver nanoparticles synthesized using Callistemon lanceolatus leaf extract

Silver nanoparticles (AgNPs) have been extensively explored due to their diverse applications in catalysis, medicine, drug delivery, etc. Physical and chemical methods of synthesizing AgNPs pose a threat to the environment due to the use of toxic and non-biodegradable substances. Green synthesis of AgNPs due to its eco-friendly nature is considered a novel approach as it can be easily scaled up and avoid the use of toxic chemicals. The aqueous extract of leaves from Callistemon lanceolatus was used in the present study for the biosynthesis of AgNPs using the Box-Behnken design (BBD) of response surface methodology (RSM). The study involves the determination of antioxidant, antibacterial, and α-amylase inhibitory activities of biosynthesized AgNPs. In addition, the photocatalytic activity of the synthesized AgNPs was assessed through the degradation of methylene blue dye. The AgNPs showed a characteristic plasmon resonance absorption band around 424 nm. Furthermore, biosynthesized AgNPs were face-centered cubic (fcc) with an average diameter of 41.93 nm as determined by XRD and TEM analysis respectively. The chemical nature of biogenic AgNPs was ascertained using energy-dispersive X-ray (EDX) analysis. Similarly, biosynthesized AgNPs were also characterized using FTIR, SEM, and DLS analysis. The AgNPs showed potential DPPH radical scavenging (IC50 of 40.86 ± 1.8 µg/mL) and α-amylase inhibitory (85.3 % at 100 µg/mL) activities. They also possessed appreciable antibacterial activity with MIC and MBC values ranging from 40 to 80 µg/mL and 60–150 µg/mL respectively. The photocatalytic degradation of methylene blue dye by AgNPs showed a rate constant of 0.009 min−1. Also, AgNPs were effective in degrading the MB dye up to 91 % in 300 min with a concentration of 0.1 mg/mL. Additionally, the reusability of AgNPs as nano-catalyst showed a small decrease in their photo-catalytic activity after every consecutive cycle up to five cycles. It may be concluded that AgNPs produced from C. lanceolatus leaf extract may have biomedical uses and applications in the purification of water contaminated with organic dyes.

Differential Changes in Some Antioxidant Enzymes and Biomolecules in Leaves of Tomato Infected by Phytophthora infestans (Mont.) de Bary

In Cameroon, tomato yields remain low due to attack by pathogens and insects. Phytophtora infestans (PI) is a phytopathogenic fungus responsible for the downy mildew of tomatoes, a fungal disease responsible for enormous economic losses. To contribute to the search for means of control, the stimulatory effect of the tomato defence system by extracts of some plants was evaluated. Tomato plants were treated with the aqueous macerates of Callistemon citrinus (C. citrinus) and Cymbopogon citratus (C. citratus) at 10% (W/V). After 4 days of spraying with the macerates, plants were inoculated with a virulent strain of PI. Tomato leaves collected at 2-day intervals for 10 days were used to determine the contents of chlorophyll a, proteins, carbohydrates, lipids, amino acids and proline. The activities of the main antioxidant enzymes were also assessed: Ascorbate Peroxidase (APX), Phenylalanine Ammonia Lyase (PAL), Peroxidase (POX), Superoxide Dismutase (SOD). The results showed that treatment of tomato plants with aqueous macerates of C. citrinus and C. citratus and their inoculation with PI induced an increase in chlorophyll a, protein, carbohydrate, lipid, amino acid and proline contents in tomato leaves; an increase in APX, PAL, POX, and SOD activities. Our results suggested that increased metabolite synthesis on the one hand, and increased enzymatic activities, on the other hand, could mitigate the oxidative damage that occured during pathogen expansion. Aqueous macerates of C. citrinus and C. citratus could be used as natural products to stimulate the defence system in tomato against Phytophtora infestans.