Preparation and evaluation of surface solid dispersion of Moringa oleifera leaf extract using freeze-drying method

Moringa leaf extract contains flavonoids, which are useful as a source of antioxidants. Its development into pharmaceutical dosage forms, however, has several problems, including thick consistency, low solubility in water, and heat-sensitive stability. Formation into surface solid dispersion (SSD) is one approach to increase the solubility of flavonoid compounds and improve the physical-mechanical characteristics of moringa leaf extract. This research aimed to develop SSD of moringa extract with microcrystalline cellulose as the carrier as well as to perform its physical and chemical characterization. The method used to prepare the SSD was freeze drying with two extract-to-microcrystalline cellulose ratios, namely 1:2 and 1:4. Results showed that the 1:2 ratio produced 6.09% moisture content and adequate powder flowability, while the 1:4 SSD system had 5.06% moisture content and poor flowability. In addition, crystallinity analysis and thermal characteristics indicated a reduction in the regularity of the crystal lattice, marked by a decrease in the specific peak intensity on the X-ray diffractogram, as well as a shift in the melting point and a decrease in the enthalpy of the SSD system in both ratios on the DSC thermogram. The total flavonoid contents of the SSD were 7.1 ± 0.0527 mg QE/g for the 1:2 ratio and 4.0 ± 0.0797 mg QE/g for the 1:4 ratio. Also, the solubility of flavonoid compounds of the 1:2 SSD system was 67.33 µg/ml, showing enhanced solubility compared to moringa leaf extract (64.11 µg/ml), physical mixture (54.60–58.81 µg/ml), and the 1:4 SSD system (48.09 µg/ml) (p