Antibacterial Activity of Lotus Leaves (Nelumbo Nucifera) Against Food-Borne Pathogens

Dual Antibacterial Properties of Copper-Coated Nanotextured Stainless Steel

Bacterial adhesion to stainless steel, an alloy commonly used in shared settings, numerous medical devices, and food and beverage sectors, can give rise to serious infections, ultimately leading to morbidity, mortality, and significant healthcare expenses. In this study, Cu-coated nanotextured stainless steel (nSS) fabrication have been demonstrated using electrochemical technique and its potential as an antibiotic-free biocidal surface against Gram-positive and negative bacteria. As nanotexture and Cu combine for dual methods of killing, this material should not contribute to drug-resistant bacteria as antibiotic use does. This approach involves applying a Cu coating on nanotextured stainless steel, resulting in an antibacterial activity within 30 min. Comprehensive characterization of the surface revealing that the Cu coating consists of metallic Cu and oxidized states (Cu2+ and Cu+), has been performed by this study. Cu-coated nSS induces a remarkable reduction of 97% in Gram-negative Escherichia coli and 99% Gram-positive Staphylococcus epidermidis bacteria. This material has potential to be used to create effective, scalable, and sustainable solutions to prevent bacterial infections caused by surface contamination without contributing to antibiotic resistance.

A Current Perspective of Plants as an Antibacterial Agent: A Review

With the emergence and evolution of bacterial strains, it is now becoming difficult for pharmaceutical industries to provide remedies required for the betterment of mankind. Continuous exposure with available medication leads to the development of new strains with a significant amount of resistance, due to which pharmaceutical industries are facing various challenges. Antimicrobial resistance is the phenomenon causing a challenge in new drug development through conventional methods. Therefore, the requirement of alternative medicine is in high demand. Recently, allopathic medicines have seen a disinterest and people are preferring natural solutions due to their fewer side effects comparable to conventional medicine. Worldwide plants are utilized for various disease treatments such as bacterial infection, skin disorders, cancer, asthma, respiratory problems, etc. The presence of a wide range of phytocompounds in different plants provides an alternative to the pharmaceutical industries to counter the problem of bacterial infections. Different plants contain various phytochemicals that possess numerous therapeutic activities and provide a remedy to suppress various bacterial strains. Therefore, in this review, an overview of various plants and their phytocompounds which are responsible for antibacterial activity has been discussed.

Extraction of Graphene Nanostructures from Colocasia esculenta and Nelumbo nucifera Leaves and Surface Functionalization with Tin Oxide: Evaluation of Their Antibacterial Properties

Expeditious evolution of antimicrobial resistance in recent years has been identified as a growing concern by various health organizations around the world. Herein, facile and environmentally benign production of highly antibacterial carbonaceous nanomaterials from Colocasia esculenta and Nelumbo nucifera leaves is reported. After carbonization and oxidative treatment, smaller graphene domains are formed in Colocasia esculenta derivatives, whereas larger sheetlike structures are observed in the case of Nelumbo nucifera. Smaller particle size makes quantum confinement effects more prominent, as is evident in fine-tuning of the photoluminescence emission after each stage of treatment. The influence of precursor materials on the antibacterial properties of the nanosystems is also demonstrated. When microbiocidal activity was tested against model bacteria Pseudomonas aeruginosa, the nanocomposite derived from Colocasia esculenta leaves showed higher activity than the antibiotic drug clarithromycin (control) with a measured zone of inhibition of 40±0.5 mm. This is one of the highest values reported in comparison with plant-based carbon-silver nanosystems. Quantitative analysis revealed that the nanocomposite obtained from Colocasia esculenta leaves has antimicrobial efficacy equivalent to those of commercial antibiotic drugs and is able to eradicate bacteria at much lower concentrations than that obtained from Nelumbo nucifera leaves.

Enhancing the Bactericidal Efficacy of Nanostructured Multifunctional Surface Using an Ultrathin Metal Coating

Insects and plants exhibit bactericidal behavior through nanostructures, which leads to physical contact killing that does not require antibiotics or chemicals. Also, certain metallic ions (e.g., Ag⁺ and Cu²⁺) are well-known to kill bacteria by disrupting their cellular functionalities. The aim of this study is to explore the improvement in bactericidal activity by combining extreme physical structure with surface chemistry. We have fabricated tall (8-9 μm high) nanostructures on silicon surfaces (NSS) having sharp tips (35-110 nm) using a single-step, maskless deep reactive ion etching technique inspired by dragonfly wing. Bactericidal efficacy of the nanostructured surfaces coated with a thin layer of silver (NSS_Ag) or copper (NSS_Cu) was measured quantitatively using standard viability plate-count method and flow cytometry. NSS_Cu surfaces kill bacteria very efficiently (killing 97% within 30 min) when compared to the uncoated NSS. This can be attributed to the addition of a surface chemistry to the nanostructures. The antibacterial activity of NSS_Cu is further indicated by the morphological differences of the dying/dead bacteria observed in the SEM images. The nanostructured surfaces demonstrate excellent superhydrophobic behavior, even with an ultrathin layer of metal (Ag/Cu) coating. The nanostructured surfaces exhibit static contact angle greater than 150° and contact hysteresis less than 10°. Moreover, reflectance is found to be <1% (for NSS_Cu < 0.5%) for all the nanostructured surfaces in the wavelength range 250-800 nm. The results obtained suggest that the fabricated nanostructured surfaces are multifunctional and can be used in various practical applications.

Evolutionary origin of the NCSI gene subfamily encoding norcoclaurine synthase is associated with the biosynthesis of benzylisoquinoline alkaloids in plants

Sacred lotus is rich in biologically active compounds, particularly benzylisoquinoline alkaloids (BIAs). Here, we report on isolation of genes encoding (S)-norcoclaurine synthase (NCS) in sacred lotus, which is a key entry-enzyme in BIA biosynthesis. Seven NCS genes, designated NnNCS1 through NnNCS7, were identified in the sacred lotus genome, and five are located next to each other within a 83 kb region on scaffold 8. The NCS genes are divided into two subfamilies, designated NCSI and NCSII. The NCSII genes are universal in plants, while the NCSI genes are only identified in a limited number of dicotyledonous taxa that produce BIAs. In sacred lotus, only NnNCS4 belongs to the NCSII subfamily, whilst the rest NCS genes within the NCSI subfamily. Overall, the NnNCS7 gene was predominantly expressed in all tested tissues, and its expression is significantly correlated with alkaloid content in leaf. In contrast, the NnNCS4 expression shows no significant correlation with alkaloid accumulation in leaf, and its lack of expression cannot inhibit alkaloid accumulation. Taken together, these results suggest that the NCSI subfamily is crucial for BIA biosynthesis, and its origin may represent an important evolutionary event that allows certain plant taxa to produce BIAs.