Current Issues - Allelopathy Journal

We evaluated the anti-enterobacterial activity of C. zeylanicum bark essential oil against

4-pathogenic enteric bacterial strains [(Salmonella sp. (non-typhoidal), Shigella dysenteriae,

Escherichia coli (ATCC 25922) and Klebsiella pneumoniae (ATCC 700603)]. The essential oil

antibacterial activity was determined by the agar well-diffusion method. The inhibition zones were

measured to determine the extent of antibacterial efficacy. C. zeylanicum bark oil exhibited

significant inhibitory effects on all tested bacterial strains, suggesting its potential as a natural

therapeutic agent to treat gastrointestinal infections. Thus cinnamon bark oil may be used to develop

alternate treatment strategies, against drug-resistant enteric pathogens. Further investigations on the

chemical composition of oil and the mechanisms underlying its antibacterial action are essential to

support its potential applications in clinical therapeutics.

This study compared the antifungal efficacy of essential oils extracted from the bark of

Cinnamomum zeylanicum and Cinnamomum camphora. The antifungal activity of essential oils was

evaluated against 7-fungal strains (Aspergillus niger, Aspergillus flavus, Trichoderma viridae,

Fusarium oxysporum, Rhizopus stolonifer, Candida albicans and Penicillium chrysogenum) using agar

well diffusion, broth microdilution for Minimum Inhibitory Concentration (MIC) and time-kill kinetic

assays. C. zeylanicum bark oil was, dominated by cinnamaldehyde (72.4 %), exhibited superior and

broad-spectrum antifungal activity. It showed remarkable efficacy against C. albicans and

F. oxysporum, resulting in complete plate clearance and very low MIC values of 0.125 % and 0.25 %,

respectively. Time-kill assays confirmed its rapid fungicidal activity against C. albicans. In contrast,

C. camphora bark oil, rich in camphor (54.8 %), displayed high activity against P. chrysogenum

(MIC 0.5 %) but no inhibition of F. oxysporum. Statistical analysis revealed strong positive correlations

between the major constituents and the observed antifungal effects. There was significant potential of

C. zeylanicum bark oil as a natural antifungal agent for applications in medicine, agriculture and food

preservation. Further research is warranted to elucidate the precise mechanisms of action, conduct

in-vivo safety and efficacy studies and develop stable formulations for clinical and commercial use.

This study aimed to evaluate the antifungal efficacy of essential bark oil of Cinnamomum

zeylanicum against many pathogenic and non-pathogenic fungal strains. Essential oil was extracted

from the bark using the hydrodistillation method with a Clevenger apparatus and antifungal activity

was assessed by the plate diffusion technique. Results showed that C. zeylanicum essential bark oil

exhibited significant antifungal activity, suggesting its potential as a natural antifungal agent. These

findings indicated that the essential oil may serve as a promising candidate for broader applications,

warranting further evaluation of its efficacy and safety for human use.

This study aimed to evaluate the antimicrobial efficacy of essential leaf oils of Cinnamomum

zeylanicum and Cinnamomum tamala against a broad spectrum of bacterial strains (Vibrio cholerae,

Alcaligenes xylosoxidans, Staphylococcus aureus, Rhizobium trifolii, Klebsiella pneumoniae, Proteus

vulgaris, Shigella dysenteriae and Streptomyces cinerochromogenes). Essential oils antibacterial

activity was assessed by the agar diffusion method. The antimicrobial activity was determined based

on the Inhibition Zones Diameter. Results indicated that both C. zeylanicum and C. tamala leaf oils

had significant antibacterial potential, suggesting their promising role as natural antibacterial agents.

These findings warrant further investigation into their efficacy and safety for potential therapeutic

applications.

We studied the protective impacts of Thymus numidicus Poiret essential oil (TEO) on the

nephrotoxicity induced by TiO2 nanoparticles (NPs) at both histological and oxidative levels. Adult

male albino rats were randomly divided into four groups: Group-I: Control, Group-II: Received

12 mg/kg/day of TiO2 NPs, Group-III: Received 4μL/kg/day of Thymus numidicus Poiret essential

oil and Group-IV: Administered Essential oil and TiO2 NPs for 30 days. Administered TiO2 NPs

significantly increased the serum uric acid levels and creatinine levels than control. Furthermore,

rats exposed to TiO2 NPs increased MDA content with reduction in renal GSH, GPx and GST

activities when compared with control. Renal toxicities induced by TiO2 NPs were evident through

disturbances in oxidative-antioxidant system and changes in serum renal markers. However, these

changes were prevented and the antioxidant status was preserved when experimental rats were

treated with Thymus numidicus Poiret essential oil. The biochemical evidence of nephroprotection

was supported by the histological findings. This study demonstrated that Thymus numidicus Poiret

essential oil significantly decreased the adverse effects of TiO2 NPs, highlighting its role in

reducing nanoparticle-induced renal dysfunction. Its nephroprotective activity was attributed to its

chemical composition and antioxidant properties.

This study aimed to investigate the hypoglycaemic effects of Trianthema portulacastrum L.,

leaves and its in-vitro potential. The study involved DPPH radical scavenging and assay inhibition,

α-amylase and α-glucosidase to evaluate in-vitro anti-oxidant and antidiabetic properties. The dried

plant material was extracted with solvents of varying polarity (Petroleum ether, Ethyl acetate and

Ethanol) using Soxhlet’s apparatus, while aqueous extraction was done by decoction. Phytochemical

study revealed major chemical components in petroleum ether, ethyl acetate, ethanol and water

extracts. Ethyl acetate extract showed the presence of phenols and flavonoids, but lacked alkaloids.

Antioxidant action of extracts was evaluated using DPPH assay. For the ethyl acetate extract of

Trianthema portulacastrum leaves, the IC50 value was 147.65 µg/ml for DPPH respectively. Among

the extracts, ethyl acetate extract exhibited significant activity compared to petroleum ether, ethanol

and aqueous extracts. Inhibition of two major enzymes α-amylase and α-glucosidase, is the most

important treatment of Diabetes mellitus. Polysaccharides and saccharides are the major component

of the human diet and α-amylase and α-glucosidase are involved in their digestion. These saccharides

are first broken down into oligosaccharides by α-amylase and then α-glucosidase covert them into

simpler sugar molecules (monosaccharides). The inhibition of the digestive enzymes involved in

polysaccharide breakdown significantly reduces the blood sugar level. The anti-diabetic activity of T.

portulacastrum against α amylase and α glucosidase inhibition assay showed concentration

dependent inhibition (%). The ethyl acetate extract exhibited dose-dependent inhibitory effects on α-

amylase and α-glucosidase, likely due to flavonoids and/or phenolic compounds and their free radical

scavenging properties. The ethyl acetate extract of Trianthema portulacastrum showed promising

antidiabetic activity.

We isolated 30-bacterial isolates from tomato (Solanum lycopersicum L.) plant rhizosphere

roots and screened their ability to mitigate the pathogenic effects of Fusarium oxysporum fungus

on tomato plant. Initially 12-isolates among 30-were selected based on their antagonistic activity

against Fusarium and5-isolates exhibited strong Plant Growth-Promoting characteristics, were

further selected and identified using 16S rDNA analysis. The PGPR consortium was prepared

comprising all 5-selected isolates and was used in this study to analyse its positive effects on the

tomato plant against Fusarium infection. The PGPR consortium was applied in the roots15-days

before Fusarium inoculation and its effect was analysed for 3-days post-infection. PGPR-treated

plants significantly improved all measured parameters like total phenolics, total proteins and five

different PR proteins like peroxidise, β-1,3-Glucanase and chitinase, while the combined PGPR

and Fusarium treatment gave consistently higher yield. These findings suggested that PGPR pre-

treatments, enhanced the resistance against the Fusarium infection.

We did phytochemical screening of Nerium oleander L.,ethanolic and aqueous extracts, to
determine the content of total polyphenols and flavonoids, to test their in-vitro antioxidant activity
by DPPH radical scavenging and antimicrobial activity using the disk diffusion method. The plant
contained flavonoids, gallic tannins, catechol tannins, saponins and terpenes. The total polyphenols
and flavonoids contents ranged from 65.321±4.93 mg GAE/g to 11.753±0.92 mg QE/g for the
aqueous extract and 88.25±3.25 mg GAE/g to 10.035±0.34 mg QE/g for the ethanolic extract,
respectively. N. oleander extracts had higher antioxidant activities (from 33.38±2.88 aqueous and
10.97±1.66 μg/mL for ethanolic). The antimicrobial properties of N. oleander extracts were
evaluated against 3-Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa and
Serratia marcescens), 2-Gram-positive bacteria (Staphylococcus epidermidis and Staphylococcus
aureus) and 2-fungal species (Candida albicans and Candida parapsilosis). Both ethanolic and
aqueous extracts demonstrated significant antimicrobial activity against all tested strains, except the
Serratia marcescens. The ethanolic extract of N. oleander showed the highest antimicrobial activity,
with inhibition zones of 15-17 mm against the most sensitive isolates. The lowest minimal
inhibitory concentration (MIC) of 39 μg/mL was observed for the ethanolic extract against C.
albicans, while the aqueous extract had an MIC of 78 μg/mL against P. aeruginosa.

This 15-days study evaluated the effects of drought stress (40 % field capacity) at the initial reproductive stage and increase of the allelopathic potential of Cosmos sulphureus Cav. Thereafter, fresh leaves were collected for malondialdehyde and proteomic tests and to prepare crude extract. Bioassays were done on crops [Lactuca sativa L., Sorghum bicolor (L.) Moench], Cucumis sativus L.] and weeds [Urochloa decumbens (Stapf) Webster, Portulaca oleracea L. and Panicum maximum Jacq.]. All extracts significantly inhibited the germination (5-90 %), depending on the species and extract concentration. However, the extracts from stressed plants were more inhibitory to germination (22.74 %), shoot growth (43.91 %) and root growth (35.60 %) than extracts from non-stressed plants (15.69 %, 44.70 % and 33.65 %, respectively). No significant differences were observed between the drought and non-stress conditions. It was concluded that drought stress (40 % field capacity) for 15-days, at the initial reproductive stage in Cosmos sulphureus Cav. plants, did not increase the allelopathic potential of this specie. These findings support further study of its bioherbicidal activity and sustainable weed control.