Correlation between Structures and Antioxidant Activities of Polyvinylpyrrolidone/Garcinia mangostana L. Extract Composite Nanofiber Mats Prepared Using Electrospinning

Hindawi Journal of Nanomaterials Volume 2017, Article ID 9687896, 10 pages https://doi.org/10.1155/2017/9687896 Research Article Correlation between Structures and Antioxidant Activities of Polyvinylpyrrolidone/Garcinia mangostana L. Extract Composite Nanofiber Mats Prepared Using Electrospinning Ida Sriyanti,1,2 Dhewa Edikresnha,1,2 Annisa Rahma,3 Muhammad Miftahul Munir,1,2 Heni Rachmawati,3,4 and Khairurrijal Khairurrijal1,2 1 Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Bandung 40132, Indonesia Bioscience and Biotechnology Research Center, Institute for Research and Community Services, Institut Teknologi Bandung, Bandung 40132, Indonesia 3 Pharmaceutics Research Division, School of Pharmacy, Institut Teknologi Bandung, Bandung 40132, Indonesia 4 Nanoscience and Nanotechnology Research Center, Institute for Research and Community Services, Institut Teknologi Bandung, Bandung 40132, Indonesia 2 Correspondence should be addressed to Khairurrijal Khairurrijal; Received 31 March 2017; Accepted 1 June 2017; Published 18 July 2017 Academic Editor: Silvia Licoccia Copyright © 2017 Ida Sriyanti et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Nanofiber mats of polyvinyl(pyrrolidone) (PVP) with Garcinia mangostana extract (GME) as the encapsulated drug have been developed using electrospinning. SEM images of all electrospun PVP/GME composite nanofiber mats showed that they had similar and smooth morphology, no beads, and spindle shape. Its average diameter decreased and its surface area therefore increased with the decrease of its PVP concentration. The benefit of high surface area is obvious in drug delivery systems for poorly water-soluble drugs. Their FTIR spectra indicated that PVP and GME interacted intermolecularly via hydrogen bonds in the composite nanofiber mats. A conformational change in the C-H chain of PVP occurred in the composite nanofiber mats due to the intermolecular interactions. Their XRD patterns confirmed that they were amorphous because of amorphization during electrospinning. The XRD analyses also strengthened the FTIR studies; namely, GME and PVP formed intermolecular interactions in the electrospun composite nanofiber mats. As a result, GME as the encapsulated drug was molecularly dispersed in the electrospun PVP nanofiber matrix that functioned as a drug delivery system. From the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, the composite nanofiber mats exhibited very high antioxidant activities despite having been exposed to high voltage during electrospinning. Therefore, they are potential antioxidant products for food and pharmaceutics. 1. Introduction Mangosteen (Garcinia mangostana L.) is widely cultivated across Indonesia. The color of mangosteen is dark purple or reddish with white, soft, and juicy edible pulp. It has slightly sour but sweet flavor as well as pleasant aroma. The fruit has been used as traditional medicine to treat abdominal pain, diarrhea, dysentery, infected wound, suppuration, and chronic ulcer. The major active substances in mangosteen pericarp are xanthones and their derivatives such as 𝛼-, 𝛽-, 𝛾mangostin, garcinone, mangostanol, and gartinin, in which 𝛼-mangostin is the major xanthone [1]. They are classified into polyphenolic compounds and have been reported to have high antioxidant activities [2–4]. Some delivery methods to improve the bioavailability of 𝛼-mangostin have recently been studied, including microgel [5], solid dispersion [6], microsphere [7], and nanofiber mat [8]. Electrospinning is a method to produce nanofiber mats with a very large surface area to volume ratio from a precursor polymer solution. An electrostatic field is applied to the precursor polymer solution to induce positive charges on the surface of the polymer solution so that when it is subjected to a very high potential difference, the positively charged polymer solution will be attracted towards the grounded 2 collector to form nanometer-size fibers [9, 10]. By adjusting properties of the polymer solution and electrostatic field during the electrospinning process, the morphology and size of the resulting fibers can be controlled. Recently, it has been reported that highly uniform polymer nanofibers could be obtained by maintaining a constant current [11]. Although the simple and straightforward electrospinning processes have developed very quickly to prepare a wide variety of complicated nanostructures such as core-sheath, Janus, and tri-layer [12–14], the mainstream is still the monolithic nanocomposites resulted from the single-fluid electrospinning processes, in which an active ingredient is homogeneously distributed within the polymeric matrix to take advantages of the nanofibers huge surface area. Polyvinylpyrrolidone (PVP) along with polyvinyl alcohol (PVA) and polyethylene glycol (PEG) are vinyl polymers that are widely used to develop products of drug delivery media [15]. Moreover, PVP is a widely used hydrophilic polymer because it is nontoxic, electrospinnable, and soluble in water, and it also has good biocompatibility [16–19]. It has also been reported that electrospun PVP nanofibers had an effective release control and it was able to increase the solubility of curcumin [20]. Although many studies have been done to load GME into polymer nanofibers, the use of PVP nanofibers, however, is rarely explored. Very recently, a short description of electrospun PVP/GME composite nanofiber mats along with the release of GME from the nanofibers has been given [18]. In this paper, we will report their antioxidant activities investigated by using the 1.1diphenyl-2-picrylhydrazyl (DPPH) assay. Their structures were also analyzed by employing a scanning electron microscope (SEM), an X-ray diffractometer (XRD), and a Fourier transforms infrared (FTIR) spectrometer. The relationship between their structures and antioxidant activities will be thoroughly discussed. 2. Materials and Methods 2.1. Materials. Polyvinylpyrrolidone (PVP) (MW 1,300 kg⋅mol−1 ) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 𝛼-mangostin standard were purchased from Sigma-Aldrich, Indonesia. Mangosteen pericarps were obtained from a local market in Bandung, Indonesia. Technical grade ethanol 96% for maceration was acquired from Bratachem, Indonesia, while analytical grade methanol used for antioxidant tests was purchased from Merck, Indonesia. 2.2. 𝛼-Mangostin Content Assay. GME paste was obtained from mangosteen pericarp extraction using the maceration method. The 𝛼-mangostin content in the GME paste and nanofiber mats was analyzed using High Performance Liquid Chromatography (HPLC). The sample was injected into a C-18 column (Phenomenex, 250 mm × 4,6 mm, particle size 5 𝜇m) using a HPLC system with a UV spectrophotometer detector (Shimadzu, SPD-20A (...truncated)