Experimental design-based optimization of lipid nanocarrier as delivery system against Mycobacterium species: in vitro and in vivo evaluation

Abstract

The study aimed to optimize self-nanoemulsifying drug delivery system using experimental design using excipients holding innate anti-mycobacterium activities followed with characterizations for responses such as optical clarity (Y₁), zone of inhibition (ZOI) against Mycobacterium smegmatis strains (Y₂, Y₃), and globular size (Y₄). The optimized formulations (OF1–OF3) were further characterized for responses and evaluated for zeta potential, minimum inhibition concentration (MIC) against non-pathogenic and tubercular strains, morphological (electron microscopy and atomic force microscopy), and confocal laser scanning microscopy (CLSM) studies. The desirability analysis suggested that the predicted values of the OF1 for the responses Y₁, Y₂, Y₃, and Y₄ were 0.137, 22.77 mm, 21.9 mm, and 191.11 nm, respectively. The morphological assessment confirmed the in vitro studies and established the inhibition mechanism as evidenced with oozing, ablation, and cell-wall fragmentation followed with cell disruption. The OF1, OF2, and OF3 showed an MIC value at 8.8 ± 0.56 mg/ml, 12.5 ± 0.22 mg/ml, and 15.0 ± 0.4 mg/ml, respectively, corroborating effectiveness against tubercular strain. CLSM studies revealed 75.1, 80.3, and 88.7% as an intense fluorescence intensity of OF1, OF2, and OF3, respectively, as compared with dye solution (∼53%). Conclusively, it can be inferred that the delivery of anti-tubercular drugs might be reassessed using excipients with inherent anti-mycobacterium activities.

Keywords:

• Mycobacterium species; electron microscopy studies
• SNEDDS formulations
• anti-tubercular study
• ex vivo CLSM

Acknowledgements

The authors thank the Birla Institute of Technology, Mesra, Ranchi, for providing the facilities and encouragement. The constructive comments and suggestions from the anonymous reviewers are gratefully acknowledged.

Disclosure statement

The authors report that they have no conflicts of interest. Authors are highly thankful to Department of Biotechnology (DBT), New Delhi, to provide Senior Research Fellow under project (No. BT/PR5653/MED/29/561/2012) for financial assistance for carrying out this work.