Preparation, in-vitro release and antioxidant potential of formulation of apigenin with hydroxypropyl-β-cyclodextrin modified microemulsion

Formulation of Chitosan-Coated Apigenin Bilosomes: In Vitro Characterization, Antimicrobial and Cytotoxicity Assessment

We prepared apigenin (APG)-loaded bilosomes (BLs) and evaluated them for vesicle size, zeta-potential and encapsulation efficiency. The formulations were prepared with cholesterol (CHL), sodium deoxy cholate (SDC), Tween 80 (T80) and phosphatidylcholine (PC) using solvent evaporation method. The prepared formulations showed the optimum result was coated with much mucoadhesive polymer chitosan (CH, 0.25 and 0.5% w/v). The chitosan-coated bilosomes (CH-BLs) were further evaluated for surface morphology, drug−polymer interaction, mucoadhesion, permeation, antimicrobial activity and cell viability. The prepared APG-BLs showed nano-metric size (211 ± 2.87 nm to 433 ± 1.98 nm), polydispersibility index <0.5, negative zeta potential (−15 to −29 mV) and enhanced encapsulation efficiency (69.5 ± 0.93 to 81.9 ± 1.3%). Based on these findings, selected formulation (F2) was further coated with chitosan and showed a marked increase in vesicle size (298 ± 3.56 nm), a positive zeta potential (+17 mV), superior encapsulation efficiency (88.1 ± 1.48%) and improved drug release (69.37 ± 1.34%). Formulation F2C1 showed significantly enhanced permeation and mucoadhesion (p < 0.05) compared to formulation F2 due to the presence of CH as a mucoadhesive polymer. The presence of CH on the surfaces of BLs helps to open the tight membrane junctions and leads to enhanced permeation. A TEM study revealed non-aggregated smooth surface vesicles. The antimicrobial and cell viability assessment revealed better effects in terms of zone of inhibition and cell line assessment against two different cancer cell line. From the study, it can be concluded that APG-CHBLs could be a superior alternative to conventional delivery systems.

Formulation of Apigenin-Cyclodextrin-Chitosan Ternary Complex: Physicochemical Characterization, In Vitro and In Vivo Studies

The current investigation was performed with an aim to improve the aqueous solubility, dissolution rate, and thus the biological activity of apigenin (APG) using the solubilizers hydroxypropyl beta-cyclodextrin (HPβCD) and chitosan (CTSN). A binary and ternary inclusion complexes of APG with HPβCD and CTSN were prepared by physical mixing, fusion, and solvent evaporation methods. The liquid state characterization of the APG, the solubilizers, and the physical and chemical interactions between them was done through phase solubility approach. The solid-state characterization was performed by proton nuclear magnetic resonance (1H-NMR), differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). The in vitro dissolution test and antioxidant activity and in vivo anti-inflammatory activity of the ternary inclusion complex in albino rats were performed to assess the performance of the APG. Phase solubility study results revealed a remarkable increase in apparent stability constant (Kc) and complexation efficiency (CE) of HPβCD in presence of CTSN in ternary complex with above 8 folds more increment in solubility of APG than its binary complex. The in vitro dissolution rate, antioxidant activity, and the anti-inflammatory effect of the APG ternary inclusion complex were found to be significantly higher than that of pure APG. Solid state characterization confirmed the formation of a ternary inclusion complex. 1H-NMR study gave more insight at molecular level into how different groups of APG were responsible for complex formation with the HPβCD and how CTSN was significantly influencing on the APG-HPβCD complex formed. Nevertheless, pharmacokinetic and histopathological studies of our APG-HPβCD-CTSN ternary complex would yield much rewarding results.

Functionality of apigenin as a potent antioxidant with emphasis on bioavailability, metabolism, action mechanism and in vitro and in vivo studies: A review

Numerous diseases such as cancer, diabetes, cardiovascular, neurodegenerative diseases, etc. are linked with overproduction of reactive oxygen species (ROS) and oxidative stress. Apigenin (5,7,4'-trihydroxyflavone) is a widely distributed flavonoid, responsible for antioxidant potential and chelating redox active metals. Being present as glycosides or polymers, the apigenin degrades to variable amount in the digestive tract; during processing, its activity is also reduced due to high temperature or Fe/Cu addition. Although its metabolism remains elusive, enteric absorption occurs sufficiently to reduce plasma indices of oxidant status. Delayed clearance in plasma and slow liver decomposition enhance its systematic bioavailability. Antioxidant mechanism of apigenin includes: oxidant enzymes inhibition, modulation of redox signaling pathways (NF-kB, Nrf2, MAPK, and P13/Akt), reinforcing enzymatic and nonenzymatic antioxidant, metal chelation, and free radical scavenging. DPPH, ORAC, ABTS, and FRAP are the major in vitro methods for determining the antioxidant potential of apigenin, whereas its protective effects in whole and living cells of animals are examined using in vivo studies. Due to limited information on antioxidant potential of apigenin, its in vitro and in vivo antioxidant effects are, therefore, discussed with action mechanism and interaction with the signaling pathways. This paper concludes that apigenin is a potent antioxidant compound to overcome the difficulties related to oxidative stress and other chronic diseases.

Advantages of the combined use of cyclodextrins and nanocarriers in drug delivery: A review

Complexation with cyclodextrins (CDs) has been widely and successfully used in pharmaceutical field, mainly for enhancing solubility, stability and bioavailability of a variety of drugs. However, some important drawbacks, including rapid removal from the bloodstream after in vivo administration, or possible replacement, in biological media, of the entrapped drug moieties by other molecules with higher affinity for the CD cavity, can limit the CDs effectiveness as drug carriers. This review is focused on combined strategies simultaneously exploiting CD complexation, and loading of the complexed drug into various colloidal carriers (liposomes, niosomes, polymeric nanoparticles, lipid nanoparticles, nanoemulsions, micelles) which have been investigated as a possible means for circumventing the problems associated with both such carriers, when used separately, and join their relative benefits in a unique delivery system. Several examples of applications have been reported, to illustrate the possible advantages achievable by such a dual strategy, depending on the CD-nanocarrier combination, and mainly resulting in enhanced performance of the delivery system and improved biopharmaceutical properties and therapeutic efficacy of drugs. The major problems and/or drawbacks found in the development of such systems, as well as the (rare) case of failures in achieving the expected improvements have also been highlighted.

Dissolution and bioavailability improvement of bioactive apigenin using solid dispersions prepared by different techniques

Apigenin (APG) is a poorly soluble bioactive compound/nutraceutical which shows poor bioavailability upon oral administration. Hence, the objective of this research work was to develop APG solid dispersions (SDs) using different techniques with the expectation to obtain improvement in its in vitro dissolution rate and in vivo bioavailability upon oral administration. Different SDs of APG were prepared by microwave, melted and kneaded technology using pluronic-F127 (PL) as a carrier. Prepared SDs were characterized using "thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infra-red (FTIR) spectrometer, powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM)". After characterization, prepared SDs of APG were studied for in vitro drug release/dissolution profile and in vivo pharmacokinetic studies. The results of TGA, DSC, FTIR, PXRD and SEM indicated successful formation of APG SDs. In vitro dissolution experiments suggested significant release of APG from all SDs (67.39-84.13%) in comparison with control (32.74%). Optimized SD of APG from each technology was subjected to in vivo pharmacokinetic study in rats. The results indicated significant improvement in oral absorption of APG from SD prepared using microwave and melted technology in comparison with pure drug and commercial capsule. The enhancement in oral bioavailability of APG from microwave SD (319.19%) was 3.19 fold as compared with marketed capsule (100.00%). Significant enhancement in the dissolution rate and oral absorption of APG from SD suggested that developed SD systems can be successfully used for oral drug delivery system of APG.

Preparation, characterization and antitumor activity evaluation of apigenin nanoparticles by the liquid antisolvent precipitation technique

The present work aimed to apply the liquid antisolvent precipitation (LAP) method for preparing the apigenin nanoparticles and thereby improving the solubility and bioavailability of apigenin. The different experimental parameters on particle size were optimized through central composite design (CCD) using the Design-Expert® software. Under the optimum conditions, the particle size of the apigenin nanosuspension was about 159.2 nm. In order to get apigenin nanoparticles, the freeze-drying method was selected and the mannitol was used as a cryoprotectant. Then the solid state properties of the apigenin nanoparticles were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermo gravimetric (TG), and X-ray diffraction (XRD). The results obtained displayed that the apigenin nanoparticles exhibited near-spherical shape and could be transformed into an amorphous form. In addition, the dissolving test, the bioavailability in rats, and the antitumor activity were also studied. The experimental results showed that the solubility of the apigenin nanoparticles were about 29.61 times and 64.81 times of raw apigenin in artificial gastric juice and in artificial intestinal juice, respectively, and the apigenin nanoparticles showed higher dissolution rates compared to raw apigenin, and was about 6.08 times and 6.14 times than that of raw apigenin in artificial gastric juice and in artificial intestinal juice. The oral bioavailability of apigenin nanoparticles was about 4.96 times higher than that of the raw apigenin, but the apigenin nanoparticles had no toxic effect on the organs of rats. In addition, the apigenin nanoparticles had a higher inhibition to HepG2 cells by lower IC50 than that of raw apigenin.

Solubility and dissolution rate improvement of the inclusion complex of apigenin with 2-hydroxypropyl-β-cyclodextrin prepared using the liquid antisolvent precipitation and solvent removal combination methods

Apigenin (AP) has many pharmacological activities. AP has poor solubility in some solvents. AP is insoluble in water and slightly soluble in ethanol (1.93 mg/ml). It has limited application and exploitation. Therefore, the liquid antisolvent precipitation (LAP) method was applied to improve the solubility of AP in ethanol by changing its crystal form or producing ultra-fine particles. Then, the inclusion complex of AP with 2-Hydroxypropyl-β-cyclodextrin (HP-β-CD) is prepared using the solvent removal method. The effects of various experimental parameters on the solubility of AP in ethanol were investigated through the single factor design. Under the optimum conditions, the AP-ethanol solution of 6.19 mg/ml was obtained. The inclusion complex of AP with HP-β-CD was obtained by the solvent removal method. The load efficiency (LE) and drug encapsulation efficiency (EE) of the inclusion complex of AP with HP-β-CD were 13.98%±0.14% and 97.86%±1.07%, respectively. SEM, FTIR, ¹HNMR, XRD, DSC and TG were used to analyze the characteristics of the inclusion complex of AP with HP-β-CD. These results showed that the inclusion complex has significantly different characteristics with AP. In addition, the dissolution rate and solubility of the inclusion complex were approximately 15.24 and 68.7 times higher than AP in artificial gastric juice, and was separately 10.4 times and 40.05 times higher than AP in artificial intestinal juice. The bioavailability of inclusion complex increased 3.97 times compared with AP.