Extended Abstract
1. Introduction
Bone cancer is an early mesenchymal tumor, i.e. histologically characterized by the production of steroids by malignant cells. It is a relatively rare malignancy and the most frequent bone malignancy. Available treatment methods often have severe adverse effects; thus, implementing medicinal plants, like Iranian nepeta (Pooneh-sa) and their derivatives has received significant attention. It is hoped that these plants, which have fewer adverse effects, could be more effective in fighting cancer cells. In modern pharmacology, numerous efforts have been made to improve drug delivery and optimize its pharmacological performance. A measure to solve this problem is applying nanotechnology, and consequently, using carriers, like niosomes. As two-layer carriers, niosomes are ideal models of biological cell membranes that work by minimizing the harmful effects on cell and tissue health.
Niosomes are carriers composed of cholesterol hydration with non-ionic surfactants in the aquatic environment; they could trap materials. Due to their biocompatibility and biodegradability along with nanoscale size, these carriers have demonstrated numerous applications in various fields, including cancer treatment [3]. The general tendency of society to use herbal medicines and natural products is increasing. Furthermore, a large share of commercial pharmaceutical products belongs to herbal medicines [4, 5]. Herbs have long been implemented to treat various human diseases. Genus Nepeta (of Lamiaceae family), known as “poone-sa” in Iran, contains different annual and perennial species. It is found in different parts of Asia, Europe, and North Africa. Approximately 250 species of this genus have been reported in different parts of the world [8]. The genus nepeta in Iran has 67 wildling species, i.e. distributed in various regions of Iran and are mostly indigenous [12].
The present study aimed to investigate the anti-cancer properties of the extract of Iranian nepeta plants (Nepeta persica) and the niosomes containing this extract against bone cancer cells.
2. Materials and Methods
Bone cancer cells (MG63 cell line) were studied in cell cultivation conditions in DMEM plant growth regulator enriched with 10% FBS in a CO2 incubator at 37°C, 5% CO2, and 95% humidity.
The MG63 cell line of bone cancer was obtained from the Cell Bank of Pasteur Institute of Iran. The extraction of the Iranian nepeta plant (Nepeta persica) was performed using the soxhlet apparatus. After drying, the dried extract was applied for further experiments. Thin-film hydration method was employed to synthesize nano-niosomes. The lipid phase consisted of span 60-cholesterol, which was formed by multiple mole ratios (F1-F3 formulations), using a rotating evaporator of a thin lipid film. Then, the thin lipid film was hydrated, homogenized, and filtered to reduce the size. After separating the free extract, the amount of the loaded extract was determined. Then, the physicochemical properties of the niosomes containing the extract, including their size and surface charge were evaluated. For this purpose, we applied a DLS and a Zetasizer device. Moreover, we evaluated it using the Scanning Electron Microscope (SEM) image of the morphology of the niosomes. Finally, the cytotoxic effect of the extract and the best formulation of the enzyme-containing niosomes (F2) were evaluated after 48 hours of treatment. We employed the MTT test on bone cancer cells for this assessment. Analysis of Variance (ANOVA) and Student’s t-test was used in SPSS for data analysis (Table 1 & Figure 1).
3. Results
Based on the loading rate of the extract in the niosomes, the F2 formulation with 79.11% loading was recognized as the optimal formulation; subsequently, it was used in other research stages. The size of the niosome nano-carrier, containing the extract was 108.6 nanometers. Besides, the surface load of the niosome nano-carrier, containing the extract averaged -38.02±1.18 mV. The SEM image suggested that the particles had the right size distribution and spherical structure and were agglomerated. The MTT test results indicated that the survival rate of the cells against these two samples was 22% and 5.88%, respectively. Thus, at the same concentrations, the niosome system significantly destroyed a higher percentage of cancer cells.
4. Discussion
In 2014, Abolfazl Shakeri et al. examined the chemical compounds and antibacterial activity and cell toxicity of Nepeta ucrainica. They concluded that the extract of this plant presented antibacterial activity, especially against gram-positive bacteria. It also controlled the growth of ovarian cancer and breast cancer (MCF-7). Eventually, cytotoxic activity was associated with significant doses against MCF-7 and A2780 [17]. Askari et al. investigated the effect of cellular toxicity of pomegranate skin extract in the form of niosomes on breast cancer. They stated that using niosomes as a carrier improves the extraction process and further reduces the survival rate. In addition, the release rate and effectiveness of the extract in the condition of cancer cells (in terms of temperature and pH) are better than nanocarriers. Such data signify that their study findings are consistent with those of the present study [23].

Using other nanocarriers to load the extract of Iranian nepeta plants and comparing it with the current research findings could provide the best nanocarrier that could induce this plant’s maximum anti-cancer properties.
Apart from the high cost of materials and services, there were no restrictions for conducting the present study.

5. Conclusion
The obtained data revealed the higher effectiveness of nano niosomic form of the extract of Iranian nepeta plant, compared to the free form of the extract; such efficacy regarded the ability to enter the cell and induce anti-cancer effects.

Ethical Considerations
Compliance with ethical guidelines
The Medical Ethics Committee of the Islamic Azad University, based on letter No. 98975, has approved this research in terms of biological ethics.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or non-profit sectors.Authors' contributions
All authors contributed in designing, running, and writing all parts of the research.
Conflicts of interest
The authors declared no conflict of interest.
Acknowledgment
The authors express their gratitude to the School of Paramedical Sciences of Yazd Shahid Sadoughi University of Medical Sciences.