Date Published: May 7, 2015
Publisher: Springer Berlin Heidelberg
Author(s): Raksha S. Pandit, Swapnil C. Gaikwad, Gauravi A. Agarkar, Aniket K. Gade, Mahendra Rai.
Curcumin is one of the polyphenols, which has been known for its medicinal use since long time. Curcumin shows poor solubility and low absorption, and therefore, its use as nanoparticles is beneficial due to their greater solubility and absorption. The main aim of the present study was the formation of curcumin nanoparticles (Nano curcu), evaluation of their antibacterial activity against human pathogenic bacteria and formulation of Nano curcu-based cream. We synthesized Nano curcu by sonication method. The synthesis of Nano curcu was assessed for their solubility in water and by UV–visible spectrophotometry. Further, the nanoparticles were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, nanoparticle tracking and analysis, and zeta potential analysis. In vitro antibacterial activity of Nano curcu was evaluated against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The cream containing Nano curcu was found to be effective against human bacterial pathogens and hence can be used for treatment of bacterial diseases.
Curcuma longa L. is a perennial herb, which belongs to family Zingiberaceae, and commonly known as turmeric. It occurs in tropical and sub-tropical regions throughout the world. It is commonly cultivated in Asian countries, mostly in India and China and is extensively used in ayurveda, unani, and siddha systems of medicine as one of the household therapies to alleviate different diseases (Araujo and Leon 2000; Chattopadhyay et al. 2004; Nawaz et al. 2011). Curcumin suppresses the activity of many bacteria such as Staphylococcus aureus, Salmonella paratyphi (Chaudhary and Sekhhon 2012) and Bacillus subtilis, B. macerans, B. licheniformis, and Azotobacter (Naz et al. 2010). Curcumin is also found to be effective against 20 types of Candida species (Martins et al. 2009). It has been observed by trials on human and mouse that oral consumption of curcumin shows less bioavailability and it undergoes intestinal metabolism (Sharma et al. 2005; Anand et al. 2007). These obstacles of curcumin can be eliminated by synthesis of curcumin nanoparticles (Nano curcu), liposomes, micelles, and phospholipid complexes which can be used for the purpose of longer circulation, permeability and increased resistance to metabolic processes (Aggarwal et al. 2006; Nawaz et al. 2011; Ravichandran 2013). Curcumin loaded in poly (lactic-coglycolic acid) (PLGA) nanospheres was synthesized by using solid/oil/water emulsion solvent evaporation technique (Mukerjee and Vishwantha 2009). PLGA-loaded Nano curcu are one of the efficient tools which can be used in the cancer therapy (Mukerjee and Vishwantha 2009). Curcumin-loaded hydrogel nanoparticles can act as an adjuvant in malarial treatment which reduces the use of antimalarial drugs (Dandekar et al. 2010).
Curcumin [1,7-bis (4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione] powder was procured from Hi-Media Laboratories Ltd., Mumbai.
Nano curcu detection was done by UV–visible spectroscopy and it was scanned in the range of 200–800 nm. The absorption spectra of curcumin in dichloromethane (control) and synthesized Nano curcu showed absorbance peak at 419 nm which is the characteristic feature of Nano curcu (Fig. 1). Further characterization of Nano curcu was performed by nanoparticles tracking and analysis system (NTA) to determine the average size and particle size distribution. From the NTA analysis, the mode value was found to be 92 nm, with the average size of 110 nm (Fig. 2). FTIR spectrum of curcumin in dichloromethane (control) and Nano curcu (experimental) was recorded. In FTIR spectrum of Nano curcu, peaks were observed at 1626, 1454, 1146 and 1037 cm−1 (Fig. 3). The zeta potential of Nano curcu was found to be −18 mV which showed moderate stability of Nano curcu (Fig. 4). The magnitude of the zeta potential gives an indication of the potential stability of the colloidal system. It is the potential which is measured, when one measures the velocity of the particles in a D.C. electric field. TEM analysis was performed to determine the size and shape of nanoparticles. It was found that Nano curcu showed spherical shape and polydisperse particles having the size range of 60–80 nm (Fig. 5). X-ray diffraction analyses are applied to determine the crystalline nature of Nano curcu. X-ray diffractograms of synthesized Nano curcu showed characteristic peaks at diffraction angle of 2θ at 23.03, 24.60, and 25.55 (Fig. 6).Fig. 1UV–vis spectra of synthesized Nano curcu. (Spectra A-curcumin powder in dichloromethane, Spectra B-Nano curcu). Inset fig comparative solubility of curcumin powder and Nano curcu. a Curcumin in water, b Nano curcu in waterFig. 2Nanoparticles tracking and analysis system (NTA) shows the size of Nano curcuFig. 3FTIR spectra of Nano curcu. a Experimental-Nano curcu, b control-curcumin in dichloromethaneFig. 4Zeta potential measurement of Nano curcu (−18 mV)Fig. 5TEM image showing size and shape of Nano curcuFig. 6X-ray diffraction pattern of synthesized Nano curcu
To confirm the synthesis of Nano curcu, solubility testing was performed in which Nano curcu were soluble in water, while curcumin powder was not soluble in water (Fig. 1 inset). It confirms the synthesis of Nano curcu. The results of UV–visible spectroscopy obtained in our study, corroborate with the result of Alam et al. (2012) and Ghosh et al. (2011) which specifies the synthesis of Nano curcu. The findings of NTA are similar with results obtained by Montes et al. (2010) for determining the size of polystyrene nanoparticles. In FTIR analysis, peaks correspond to different functional groups. Among these, the absorption peak at 1626 cm−1 can be assigned for C=C stretching, 1452 cm−1 corresponds to C=H, and the absorption at 1146 cm−1 due to C–H stretching. The absorption peak at 1037 cm−1 might be due to C–N stretch. The absorption spectra of control might be attributed to the functional group such as benzene ring, C–O–C bond, and aromatic C–H stretching. These finding are supported by many researchers (Yadav et al. 2009; Yen et al. 2010; Sav et al. 2012). Zeta potential measurement is used to characterize the surface charge of Nano curcu. The nanoparticles in colloidal suspension or emulsion carry electric charge which may be positive or negative. The synthesized Nano curcu were moderately stable. The X-Ray diffraction pattern confirms the crystals of Nano curcu which correspond with the results obtained by Sav et al. (2012) and Yen et al. (2010). Antibacterial activity of Nano curcu and silver nanoparticles alone was found to be more or less similar. But when Nano curcu and silver nanoparticles both were used in combination, it showed less zone of inhibition as compared with silver and Nano curcu when it is tested singly against different bacteria. Gentamycin showed higher activity against Gram-negative bacteria, whereas chloramphenicol showed better action against Gram-positive bacteria. From in vitro antibacterial assay of Nano curcu, it was found that Nano curcu showed better antimicrobial activity against Gram-negative bacteria as compared to Gram-positive ones, whereas bulk curcumin is more effective against Gram-positive bacteria. The variation in activities among bacteria may reflect differences in cell wall structures and composition between Gram-negative and Gram-positive bacteria.
The phenolic group in Nano curcu interacts with outer lipopolysaccharide layer present in the Gram-negative bacteria. Moreover, less peptidoglycan content helps in the weakening and breakage of bacterial cell wall, resulting in the death of the bacterial cell. In addition, antibacterial cream of Nano curcu possesses both the water phase and oil phase. Both the phases are stabilized by surfactant. The oil phase of the cream helps in the better interaction of Nano curcu with the outer lipopolysaccharide layer present in the Gram-negative bacteria, thereby causing the disruption of the less rigid cell wall of the Gram-negative bacteria (Fig. 10).Fig. 10Proposed mechanism for antimicrobial activity of Nano curcu
Nano curcu were fabricated by physico-chemical method. It is simple, natural, and easy method used for the synthesis of Nano curcu. Synthesized nanoparticles showed its efficacy against bacteria, viz., E. coli, S. aureus, and P. aeruginosa. It can be concluded from the results that Nano curcu synthesized by sonication method inhibited activity of bacteria. The formulated cream is new generation of antiseptic cream, which could be used in the treatment of infection caused by E. coli, S. aureus, and P. aeruginosa. The Nano curcu could also be used for wound healing.