With the successful clinical trials, multifunctional glycoprotein bovine lactoferrin is gaining attention as a safe nutraceutical and biologic drug targeting cancer, chronic-inflammatory, viral and microbial diseases. Interestingly, recent findings that human lactoferrin oligomerizes under simulated physiological conditions signify the possible role of oligomerization in the multifunctional activities of lactoferrin molecule during infections and in disease targeting signaling pathways. Here we report the purification and physicochemical characterization of high molecular weight biomacromolecular complex containing bovine lactoferrin (≥250 kDa), from bovine colostrum, a naturally enriched source of lactoferrin. It showed structural similarities to native monomeric iron free (Apo) lactoferrin (∼78–80 kDa), retained anti-bovine lactoferrin antibody specific binding and displayed potential receptor binding properties when tested for cellular internalization. It further displayed higher thermal stability and better resistance to gut enzyme digestion than native bLf monomer. High molecular weight bovine lactoferrin was functionally bioactive and inhibited significantly the cell proliferation (p<0.01) of human breast and colon carcinoma derived cells. It induced significantly higher cancer cell death (apoptosis) and cytotoxicity in a dose-dependent manner in cancer cells than the normal intestinal cells. Upon cellular internalization, it led to the up-regulation of caspase-3 expression and degradation of actin. In order to identify the cutting edge future potential of this bio-macromolecule in medicine over the monomer, its in-depth structural and functional properties need to be investigated further.

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Polymannose (PM) having a weight-average molar mass (M) of 30-53 kDa was synthesized by the polycondensation of mannose using phosphorous acid as the catalyst and characterized by various techniques such as NMR, IR, GPC and polarimetry. 2D NMR results confirmed the presence of (1 → 6)-linked α-D-mannose residues as backbone with O-3 and O-2 substituted linear or branched chains in PM. Amphotericin B (AmB) was conjugated to periodate-oxidized PM through Schiff's linkages at 20 wt% concentration. The AmB-PM conjugates were highly soluble in phosphate buffered saline (180-250 mg/mL), exhibited negligible hemolytic potential to human erythrocytes even at a concentration of 200 μg/mL (equivalent to ~40 μg/mL AmB) and were non-toxic to human embryonic kidney (HEK293T) cells even at a concentration of 250 μg/mL (equivalent to ~50 μg/mL AmB). The minimum inhibitory concentration of the AmB-PM conjugates against C. albicans, C. parapsilosis and C. neoformans was in the range of 0.5-1.0 μg/mL. Mannose receptors are widely expressed on myeloid cells such as macrophages, neutrophils, and dendritic cells. Therefore, apart from treating fungal infections, AmB-PM conjugates also may have therapeutic potential for the treatment of macrophage-associated diseases such as leishmaniasis where mannose receptors are overexpressed.

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Understanding the cellular target structure and thereby proposing the best delivery system to achieve sustained release of drugs has always been a significant area of focus in biomedical research for translational benefits. Specific targeting of the receptors expressed on the target cell represents an effective strategy for increasing the pharmacological efficacy of the administered drug. Liposomes offer enhanced conveyance as a potential carrier of biomacromolecules such as anti-cancer proteins, drugs and siRNA for targeting tumour cell death. Commonly used liposomal constructs for various therapies are Doxil, Myocet, DepoCyt and Abraxanes. However, recent strategy of using multifunctional liposomes for the sustained release of drugs with increased plasma residence time and monoclonal antibody-based targeting of tumours coupled with imaging modalities have attracted enormous scientific attention. The ability of liposomes coated with specific ligands such as Apo-E derived RGD R9 and Tat peptide, to reverse the conceptualisation of drug resistance and cross the blood brain barrier, provides promising future for their use as an efficient drug delivery system. By outlining the recent advancements and innovations in the established concept of liposomal drug delivery, this review will focus on the multifunctional liposomes as an emerging novel lipid based drug delivery system.