Siriporn Okonogi

Curcumin nanoformulations: A review of pharmaceutical properties and preclinical studies and clinical data related to cancer treatment

Curcumin, a natural yellow phenolic compound, is present in many kinds of herbs, particularly in Curcuma longa Linn. (turmeric). It is a natural antioxidant and has shown many pharmacological activities such as anti-inflammatory, anti-microbial, anti-cancer, and anti-Alzheimer in both preclinical and clinical studies. Moreover, curcumin has hepatoprotective, nephroprotective, cardioprotective, neuroprotective, hypoglycemic, antirheumatic, and antidiabetic activities and it also suppresses thrombosis and protects against myocardial infarction. Particularly, curcumin has demonstrated efficacy as an anticancer agent, but a limiting factor is its extremely low aqueous solubility which hampers its use as therapeutic agent. Therefore, many technologies have been developed and applied to overcome this limitation. In this review, we summarize the recent works on the design and development of nano-sized delivery systems for curcumin, including liposomes, polymeric nanoparticles and micelles, conjugates, peptide carriers, cyclodextrins, solid dispersions, lipid nanoparticles and emulsions. Efficacy studies of curcumin nanoformulations using cancer cell lines and in vivo models as well as up-to-date human clinical trials are also discussed.

Dissolution improvement of high drug-loaded solid dispersion.

This study focused on an investigation of a high drug-loaded solid dispersion system consisting of drug, carrier, and surfactant. Solid dispersions of a water-insoluble ofloxacin (OFX) with polyethylene glycol (PEG) of different molecular weights, namely binary solid dispersion systems, were prepared at drug to carrier not less than 5∶5. Polysorbate 80, a nonionic surfactant, was incorporated into the binary solid dispersion systems as the third component to obtain the ternary solid dispersion systems. The powder x-ray diffraction and differential scanning calorimetric studies indicated that crystalline OFX existed in the solid dispersions with high drug loading. However, a decreased crystallinity of the solid dispersions obtained revealed that a portion of OFX was in an amorphous state. The results indicated a remarkably improved dissolution of drug from the ternary solid dispersion systems when compared with the binary solid dispersion systems. This was because of polysorbate 80, which improved wettability and solubilized the non-molecularly dispersed or crystalline fraction of OFX.

Preparation of lipid nanoemulsions incorporating curcumin for cancer therapy

The aim of this study was to develop a new formulation of a curcumin lipid nanoemulsion having the smallest particle size, the highest loading, and a good physical stability for cancer chemotherapy. Curcumin lipid nanoemulsions were prepared by a modified thin-film hydration method followed by sonication. Soybean oil, hydrogenated L-α-phosphatidylcholine from egg yolk, and cosurfactants were used to formulate the emulsions. The resultant nanoemulsions showed mean particle diameter of 47–55 nm, could incorporate 23–28 mg curcumin per 30 mL, and were stable in particle size for 60 days at 4°C. The cytotoxicity studies of curucumin solution and curcumin-loaded nanoemulsion using B16F10 and leukemic cell lines showed IC50 values ranging from 3.5 to 30.1 and 22.2 to 53.7 μM, respectively. These results demonstrated the successful incorporation of curcumin into lipid nanoemulsion particles with small particle size, high loading capacity, good physical stability, and preserved cytotoxicity.

Development of tablets containing probiotics: Effects of formulation and processing parameters on bacterial viability.

The probiotic products available in the market nowadays are mostly in the form of liquid or semisolid formulations which show low cell viability after oral administration, mainly because the bacteria do not survive the harsh conditions in the stomach. The development of suitable dry dosage forms enable higher bacterial survival and consequently is the main aim of the present study. An anticipated advantage is that due to the low water-activity lyophilized bacterial cells will preserve their viability. Further, by a proper selection of a tablet forming matrix, it is foreseen that the entrapped bacteria are protected against the low pH in the stomach. In this study, the effects on bacterial survival in tablets were investigated concerning compression force, matrix forming excipients such as hydroxypropyl methylcellulose phthalate (HPMCP) or other swelling agents. The results showed that the proportion of matrix forming excipients in tablets and the compression force affected the properties of probiotic tablets in terms of tensile strength and disintegration as well as the survival of the bacteria. The tensile strength of the tablets increased with increase of HPMCP content. Tablets manufactured with high compression force showed a slow disintegration time and high bacterial cell viability (more than 80%). Incorporation of sodium alginate in the tablets resulted in higher cell survival in simulated GI fluid (>90%) and a suitable disintegration time (approximately 5h). By a proper design of the formulation, tablets with a fast disintegration time and a high preservation of bacterial cell viability were developed.

Investigation of fruit peel extracts as sources for compounds with antioxidant and antiproliferative activities against human cell lines

The aim of this study was to evaluate antioxidant activity and cytotoxicity against human cell lines of fruit peel extracts from rambutan, mangosteen and coconut. The highest antioxidant activity was found from rambutan peel crude extract where the highest radical scavenging capacity via ABTS assay was from its ethyl acetate fraction with a TEAC value of 23.0mM/mg and the highest ferric ion reduction activity via FRAP assay was from its methanol fraction with an EC value of 20.2mM/mg. Importantly, using both assays, these fractions had a higher antioxidant activity than butylated hydroxyl toluene and vitamin E. It was shown that the ethyl acetate fraction of rambutan peel had the highest polyphenolic content with a gallic acid equivalent of 2.3mg/mL. The results indicate that the polyphenolic compounds are responsible for the observed antioxidant activity of the extracts. Interestingly, the hexane fraction of coconut peel showed a potent cytotoxic effect on KB cell line by MTT assay (IC(50)=7.7 microg/mL), and no detectable cytotoxicity toward normal cells. We concluded that the ethyl acetate fraction of rambutan peel is a promising resource for potential novel antioxidant agents whereas the hexane fraction of coconut peel may contain novel anticancer compounds.

Preparation and Characterization of Cephalexin Loaded PLGA Microspheres

The aim of this study was to evaluate the effects of emulsion type and process parameters on the properties of CPX-loaded PLGA microspheres in order to obtain delivery systems suitable for the treatment of dairy mastitis. The microsphere size was analyzed by photon correlation spectrophotometry. Determination of the drug loading was achieved by HPLC. It was found that CPX-loaded PLGA microspheres prepared using a w/o/w double emulsion technology were slightly larger (approximately 3-5 microm) but much higher in drug content (approximately 18% w/w) than those obtained using o/w single emulsion preparation technology (average size was 2 microm, encapsulation efficiency was less than 2 %). It was also demonstrated that stirring during emulsification and a change in both the internal and external phase of the emulsion, affected the size and the drug entrapment efficiency of the microspheres obtained. A 60/40 v/v mixture of chloroform and acetone was found to be the best organic solvent system for creating the primary emulsion. To obtain a high yield (>90%) of microspheres with a desirable size and high drug entrapment efficacy, a stirring rate of 8,000-10,000 rpm gave the best results. It is concluded CPX-loaded PLGA microspheres with suitable characteristics for the treatment of cows with dairy mastitis can be prepared by a w/o/w double emulsion preparation method.

Two flavonol glycosides from seeds of Camellia sinensis

Two novel flavonol triglycosides, camelliaside A and B, have been isolated from seeds of Camellia sinensis. The structures were determined to be kaempferol 3-O-[2-O-beta-D- galactopyranosyl-6-O-alpha-L-rhamnopyranosyl]-beta-D-glucopyranoside and kaempferol 3-O-[2-O-beta- D-xylopyranosyl-6-O-alpha-L-rhamnopyranosyl]-beta-D-glucopyranoside on the basis of spectroscopic, chemical and enzymatic studies. These types of interglycosidic linkages, Gal(1----2)[Rha(1----6)]Glc and Xyl(1----2)[Rha(1----6)]Glc, have not been reported previously in flavone and flavonol glycosides.

Enhanced gentamicin loading and release of PLGA and PLHMGA microspheres by varying the formulation parameters

The purpose of this study was to develop a suitable formulation for gentamicin sulfate (GS) that gives a sustained release of the drug. Therefore this drug was loaded into poly(D,L-lactide-co-glycolide) (PLGA) and poly(lactic-co-hydroxymethyl glycolic acid) (PLHMGA) microspheres. The effects of various formulation parameters (ethanol, surfactant, osmotic value of the external phase, polymer type and concentration) on particle characteristics (size, loading and release) were investigated. The GS loaded microspheres were prepared using a double emulsion evaporation technique. The results demonstrate that neither ethanol nor surfactants had beneficial effects on the drug loading efficiency (around 4-10%). However, an increase in buffer concentration (and thus osmotic pressure) of the external phase resulted in a substantial increase of GS-loading (from 10 to 28%). Further, an increase of concentration of PLGA in DCM from 10% to 15/20% caused a 4-time increase of the drug loading. The best formulation identified in this study had a loading efficiency of around 70% resulting in PLGA microspheres with a 6% (w/w) loading. The particles showed a burst release of the drug depending on their porosity, followed by a phase of 35 days where hardly any release occurred. The drug was then slowly released for around 25 days likely due to degradation of the microspheres. The drug loading efficiency of GS in PLHMGA was not significantly different from PLGA microspheres (64%). The release of GS from PLHMGA microspheres was faster than that of PLGA because the degradation rate of PLHMGA is more rapid than PLGA. This study shows that prolonged release of gentamicin can be obtained by loading this drug into microspheres made of biodegradable aliphatic polyesters.

PEG-OCL micelles for quercetin solubilization and inhibition of cancer cell growth

In this study, quercetin (QCT), a flavonoid with high anticancer potential, was loaded into polymeric micelles of PEG-OCL (poly(ethylene glycol)-b-oligo(ε-caprolactone)) with naphthyl or benzyl end groups in order to increase its aqueous solubility. The cytostatic activity of the QCT-loaded micelles toward different human cancer cell lines and normal cells was investigated. The results showed that the solubility of QCT entrapped in mPEG750-b-OCL micelles was substantially increased up to 1 mg/ml, which is approximately 110 times higher than that of its solubility in water (9 μg/ml). The average particle size of QCT-loaded micelles ranged from 14 to 19 nm. The QCT loading capacity of the polymeric micelles with naphthyl groups was higher than that with benzyl groups (10% and 6%, respectively). QCT-loaded, benzyl- and naphthyl-modified micelles effectively inhibited the growth of both sensitive and resistance cancer cells (human erythromyelogenous leukemia cells (K562) and small lung carcinoma cells (GLC4)). However, the benzyl-modified micelles have a good cytocompatibility (in the concentration range investigated (up to 100 μg/ml), they are well tolerated by living cells), whereas their naphthyl counterparts showed some cytotoxicity at higher concentrations (60-100 μg/ml). Flow cytometry demonstrated that the mechanism underlying the growth inhibitory effect of QCT in its free form was inducing cell cycle arrest at the G2/M phase. Benzyl-modified micelles loaded with QCT also exhibited this cycle arresting the effect of cancer cells. In conclusion, this paper shows the enhancement of solubility and cell cycle arrest of QCT loaded into micelles composed of mPEG750-b-OCL modified with benzyl end groups. These micelles are therefore considered to be an attractive vehicle for the (targeted) delivery of QCT to tumors.

Inhibition of cholinesterase by essential oil from food plant

Inhibition of cholinesterase has attracted much attention recently because of its potential for the treatment of Alzheimers disease. In this work, the anticholinesterase activities of plant oils were investigated using Ellmans colorimetric method. The results indicate that essential oils obtained from Melissa officinalis leaf and Citrus aurantifolia leaf showed high acetylcholinesterase and butyrylcholinesterase co-inhibitory activities. C. aurantifolia leaf oil revealed in this study has an IC(50) value on acetylcholinesterase and butyrylcholinesterase of 139 ± 35 and 42 ± 5 μg/ml, respectively. GC/MS analysis revealed that the major constituents of C. aurantifolia leaf oil are monoterpenoids including limonene, l-camphor, citronellol, o-cymene and 1,8-cineole.