No abstract

Gradual emergence of new bacterial strains, resistant to one or more antibiotics, necessitates development of new antibacterials to prevent us from newly evolved disease-causing, drug-resistant, pathogenic bacteria. Different inorganic and organic compounds have been synthesized as antibacterials, but with the problem of toxicity. Other alternatives of using green products, i.e., the medicinal plant extracts with biocompatible and potent antibacterial characteristics, also had limitation because of their low aqueous solubility and therefore less bioavailability. Use of nanotechnological strategy appears to be a savior, where phytochemicals are nanonized through encapsulation or entrapment within inorganic or organic hydrophilic capping agents. Nanonization of such products not only makes them water soluble but also helps to attain high surface to volume ratio and therefore high reaction area of the nanonized products with better therapeutic potential, over that of the equivalent amount of raw bulk products. Medicinal plant extracts, whose prime components are flavonoids, alkaloids, terpenoids, polyphenolic compounds, and essential oils, are in one hand nanonized (capped and stabilized) by polymers, lipids, or clay materials for developing nanodrugs; on the other hand, high antioxidant activity of those plant extracts is also used to reduce various metal salts to produce metallic nanoparticles. In this review, five medicinal plants, viz., tulsi (Ocimum sanctum), turmeric (Curcuma longa), aloe vera (Aloe vera), oregano (Oregano vulgare), and eucalyptus (Eucalyptus globulus), with promising antibacterial potential and the nanoformulations associated with the plants’ crude extracts and their respective major components (eugenol, curcumin, anthraquinone, carvacrol, eucalyptus oil) have been discussed with respect to their antibacterial potency.

No abstract

This study dealt with nanonization of eugenol, a major phytochemical present in basil leaf, which has pharmacological potential as an anti-bacterial agent. Eugenol nanoparticle (ENP) was synthesized by simple ultrasonic cavitation method through emulsification of hydrophobic eugenol into hydrophilic gelatin. Thus, the nanonization process made the water-insoluble eugenol to water-soluble nano-eugenol, making the nano-form bioavailable. The average size of the ENPs was 20-30 nm. Entrapment efficiency of eugenol within gelatin cap was about 80% of the eugenol, that was used as precursor in the nanonization reaction. In vitro release of eugenol from gelatin cap was slow and sustained over a period of five days. The ENP had higher anti-biofilm potency than eugenol for both formation and eradication of biofilm, formed by clinically relevant pathogen Pseudomonas aeruginosa. Minimal biofilm inhibitory concentration and minimal biofilm eradication concentration of ENPs were 2.0 and 4.0 mM respectively. In addition, the measurement of P. aeruginosa biofilm biomass, biofilm pellicle formation, biofilm thickness, amount of biofilm-forming extra-polymeric substance, cell surface hydrophobicity, cell swarming and twitching efficiencies, cellular morphology and biofilm formation in catheter demonstrated that the anti-biofilm efficacy of nano-eugenol was 30-40% higher than that of bulk eugenol. Thus, ENP can be used as a potential drug against pneumonia, a chronic infection in lung caused by P. aeruginosa, which is difficult to treat with antibiotics, due to natural intrinsic resistance of biofilm-formed cells to most antibiotics. The overall actions of ENP have been presented in the figure 1.