Cytotoxic and Nitric Oxide Inhibition Activities of Propolis Extract along with Microencapsulation by Complex Coacervation

Abstract

In this study, cytotoxicity of ethanol extract of propolis (EEP) originating from Sivas, Turkey was screened against several cancer cell lines, namely PC-3, U87MG, A-549, mPANC96, CaCo-2, MCF-7, HeLa, MDA-MB-231 and a non-tumor cell line HEK293 by MTT assay. The inhibition levels of inducible nitric oxide synthase (iNOS) were also determined by using RAW 264.7 macrophage cells following lipopolysaccharide (LPS) treatment. EEP exhibited significant cytotoxic nitric oxide inhibition activities with an IC50 value of 0.1 ± 0.1 μg/ml indicating a high potential as an anti-inflammatory agent. In spite of these promising results and the fact that propolis is a highly nutritive substance, its low solubility and bitter taste limit the applications as a natural supplement. Encapsulation might serve as a good strategy in order to overcome these problems. Complex coacervation was applied where the main focus was on surfactant type, polymer ratio (alginate:gelatin), stirring rate and concentration of core material. The mean particle size of unloaded microparticles were 22.62 μm obtained with gelatin:alginate ratio of 1:1 at a stirring rate of 1400 rpm with 2 ml of 1 % (w/v) sodium carboxymethyl cellulose (Na-CMC), whereas addition of EEP at a concentration of 100 mg/ml increased the mean particle size to 36.44 μm and yielded an encapsulation efficiency of 98.77 %. The cytotoxicities of EEP loaded microparticles were also assessed both on MCF-7 and MDA-MB-231 where similar results were achieved as free EEP which can enhance the possible use of propolis extract in the industry as a natural supplement.

Propolis attenuates lipopolysaccharide‐induced inflammatory responses through intracellular ROS and NO levels along with downregulation of IL‐1β and IL‐6 expressions in murine RAW 264.7 macrophages

“…They showed that NO and IFN‐γ production had significantly inhibited EEP by decreasing iNOS expression. In the study on EEP in Turkey, the inhibition of NO production with IC 50 value of 0.1 ± 0.1 μg/ml without causing any cytotoxic effect on iNOS was reported (Onbas et al, ). In another investigation, Brazilian red propolis (BRP 60 μg/ml) inhibited 65% of NO production without any effects on cell viability (Bueno‐Silva et al, ).…”

“…Propolis extracts from various sources also showed that the given substance could act on host nonspecific immunity activating macrophages and inhibit nitric oxide production (Almeida & Menezes, ). Moreover, inhibition of NO production by low doses of PEEP extract probably affected its anti‐inflammatory and immunoregulatory activities (Onbas, Kazan, Nalbantsoy, & Yesil‐Celiktas, ). In this respect, Song et al () investigated the inhibition of NO production against RAW 264.7 macrophages with various concentrations of EEP.…”

“…In the present study using 15 and 1.5µg/ml of PEEP, the results showed that it was not able to inhibit NO production; nonetheless, a lower dose of PEEP (0.15 µg/ml) significantly inhibited NO production ( p < 0.05). More studies have further shown low concentrations of propolis extract containing high content of flavonoids that could attribute to the inhibition of the inducible NOS (iNOS) activity (Olszanecki, Gebska, Kozlovski, & Gryglewski, ; Onbas et al, ).…”

Effect of Stryphnodendron adstringens (Mart.) Coville extract in aerobic and anaerobic microorganisms and mammalian cells

“…This shows the importance of the current study because we found that S. adstringens may be a potential NO inhibitor. Some natural extracts and their phytochemicals, such as Apios americana (Seo et al, 2018), Inula Japonica (Jin et al, 2016), and the propolis ethanolic extract (Onbas et al, 2016) have demonstrated potent NO inhibitor effect when evaluated on LPS-stimulated RAW 264.7 cells.…”

Insight on Propolis from Mediterranean Countries: Chemical Composition, Biological Activities and Application Fields

“…This high potential of propolis as antitumoral agents was related to its constituents especially its phenolic content. Moreover, Onbas et al [243] have formed a microencapsulation by complex coacervation of propolis and screened its anti-inflammatory and cytotoxic potential on cancer cells, and have found that this complex has same activity as compared with propolis in free form, and suggested its possible use in the industry for the formulation of natural supplement.…”