Abstract
Vitamin D3 (Cholecalciferol, Chc) plays a critical role in the prevention and treatment of osteoporosis. However, Chc’s clinical and nutritional applications are substantially limited by poor aqueous solubility, low stability, and inadequate bioavailability. In this study, we developed a nano-micellar delivery system by encapsulating Chc with disodium glycyrrhizin (Na2GA) to form Chc-Na2GA micelles, aiming to overcome these limitations. The resulting formulation exhibited markedly improved solubility, enhanced physicochemical stability, increased bioavailability, and a higher hepatic accumulation rate. Importantly, Chc-Na2GA treatment significantly enhanced anti-osteoporotic efficacy, accompanied by the upregulation of key osteogenesis-related genes, including bmp2a, bump4, col2a, runx2a, and sp7. Structural analysis revealed that Chc was present in an amorphous state within the micelles, stabilized primarily through hydrogen bonding and Pi-alkyl interactions. Overall, this study demonstrates that Na2GA-based nano-micellization is an effective strategy to improve the delivery and biological efficacy of hydrophobic vitamin D3, highlighting its potential significance for pharmaceutical and food applications in osteoporosis management.
Highlights
- The bioavailability of encapsulated vitamin D3 has increased by 40 %.
- The anti-osteoporotic effects of encapsulated vitamin D3 has increased by 80 %.
- Five key genes involved in the involved in osteogenesis have been upregulated.
- Hydrogen bond contributes to the increased solubility and stability of vitamin D3.
- The amorphous surface of the encapsulated vitamin D3 facilitates the adsorption.
Introduction
Cholecalciferol (Chc), also known as plain vitamin D3, is a dietary supplement for people with vitamin D deficiency [1], [2]. It is also effective in preventing bone loss and osteoporosis [3], [4]. Osteoporosis is a prevalent systemic skeletal disorder characterized by reduced bone mineral density and impaired bone microarchitecture [4]. The development of osteoporosis is largely driven by the age-related decline in bone remodeling processes [5], [6]. Internal Chc is first converted to 25-hydroxyvitamin D3 (calcifediol, 25-OH-Chc) in the liver. The calcifediol is then converted to 1,25-dihydroxyvitamin D (calcitriol) in the kidneys [3]. Calcitriol increases intestinal calcium absorption [7], [8], and suppresses parathyroid hormones that helps bone resorption [9].
Since the in vivo activation of Chc is gradually conducted by patic 25-hydroxylase and renal 1α-hydroxylase [3], [10], its delivery holds great significance in the conversion rate. Since Chc is a highly hydrophobic molecule that rarely dissolves in water [11], the absorption of oral-taken Chc primarily relies on the fat absorption route that involves bile acids incorporation [12]. Chc can also be absorbed by cholesterol transporters [13]. However, these routes are very inefficient when compared to direct dissolution and subsequent intestinal absorption. Chc is also vulnerable to oxygen, light, and humidity [14]. These characteristics add complexity and expense to its production and distribution.
To address the low solubility of drugs, various formulation strategies have been explored, such as emulsification, mechanochemistry [11], [15], and nanoparticles formed by metal, selenium, chitosan, and magnetic nanocomposite [16], [17], [18], [19]. Emulsification is a common strategy that dispersed Chc into lipid-based carriers, shielding it from light, heat, and oxidation [15], [20]. However, the emulsions can be destabilized by coalescence, droplet flocculation, gravitational separation, and Ostwald ripening [21], [22]. Recently, mechanochemistry process has emerged as a good approach for delivering hydrophobic and unstable compounds [23], [24]. This innovative technology involves the application of mechanical energy, such as grinding, milling, or high-shear mixing, to induce chemical and physical transformations [25], [26]. The technique disrupts crystalline molecular structures, reduce particle sizes, and induce amorphization, significantly improving the solubility and dissolution rate [27], [28], [29], [30]. Importantly, mechanochemical techniques increase not only the solubility and stability of bioactive compounds, but also their bioavailability and therapeutic effects [31], [32].
In this work, a focused literature survey was conducted using the databases PubMed, Web of Science, Scopus, and Google Scholar. Publications from January 2000 to March 2025 were considered. Keywords included ‘vitamin D3’, ‘cholecalciferol delivery’, ‘mechanochemistry’, ‘nano-micelles’, ‘bioavailability’, and ‘osteoporosis therapy’. Only peer-reviewed articles written in English and reporting experimental or clinically relevant data were included. The collected literature was used to compare formulation strategies, evaluate biological relevance, and position the present work within current therapeutic developments.
In the present work, we employed a mechanochemical formulation strategy to address the challenges associated with Chc. Chc is encapsulated with disodium glycyrrhizin (Na2GA) [33] to generate nano micelles, Chc-Na2GA. It exhibits not only improved solubility and stability, but also bioavailability and hepatic accumulation rate. Chc-Na2GA introduced significantly enhanced anti-osteoporotic effects and increased expression of keenly relevant genes, bmp2a, bump4, col2a, runx2a, and sp7. The amorphous Chc-Na2GA micelle is sustained by hydrogen bonds and Pi-alkyl interactions. Osteoporosis represents a major global public health burden, particularly in aging populations, with increasing incidence, fracture risk, and socioeconomic cost. Despite widespread vitamin D supplementation, therapeutic outcomes remain highly variable due to limitations in bioavailability and metabolic activation of conventional formulations. Therefore, the development of more efficient and reliable vitamin D delivery strategies is of considerable clinical and scientific importance for improving long-term management of bone metabolic disorders. This preparation process has great potential for pharmaceutical and food applications, offering a promising solution for hydrophobic drug delivery.
Continue reading here
Weifeng Hu, Min Zhu, Yihan Wen, Yi Guo, Pei Qiao, Encapsulation promotes the anti-osteoporosis effects of vitamin D3 with enhanced bioavailability and activation efficiency, Process Biochemistry, Volume 162, 2026, Pages 24-31, ISSN 1359-5113, https://doi.org/10.1016/j.procbio.2026.01.006.
