Design, characterization andin vitroevaluation of SMEDDS containing an anticancer peptide, linear LyP-1

The role of peptide-based therapeutics in oncotherapy

Cancer is the second leading cause of death worldwide, and the search for specialised therapy options has been a challenge for decades. The emergence of active targeted therapies provides the opportunity to treat cancerous tissues without harming healthy ones due to peculiar physiological changes. Herein, peptides and peptide analogs have been gaining a lot of attention over the last decade, especially for the on-site delivery of therapeutics to target tissues in order to achieve efficient and reliable cancer treatment. Combining peptides with highly efficient drug delivery platforms could potentially eliminate off-target adverse effects encountered during active targeting of conventional chemotherapeutics. Small size, ease of production and characterisation, low immunogenicity and satisfactory binding affinity of peptides offer some advantages over other complex targeting moiety, no wonder the market of peptide-based drugs continues to expand expeditiously. It is estimated that the global peptide drug market will be worth around USD 48.04 billion by 2025, with a compound annual growth rate of 9.4%. In this review, the current state of art of peptide-based therapeutics with special interest on tumour targeting peptides has been discussed. Moreover, various active targeting strategies such as the use functionalised peptides or peptide analogs are also elaborated.

Lipid Drug Carriers for Cancer Therapeutics: An Insight into Lymphatic Targeting, P-gp, CYP3A4 Modulation and Bioavailability Enhancement

In the treatment of cancer, chemotherapy plays an important role though the efficacy of anti-cancer drug administered orally is limited, due to their poor solubility in physiological medium, inability to cross biological membrane, high Para-glycoprotein (P-gp) mediated drug efflux, and pre-systemic metabolism. These all factors cumulatively reduce drug exposure at the target site leading to multidrug resistance (MDR). Lipid based carriers systems has been explored to overcome solubility and permeability related issues of anti-cancer drugs. The lipid based formulations have also been reported to circumvent the effect of P-gp and CYP3A4. Further long chain triglycerides (LCT) has shown their ability to access Lymphatic route over Medium Chain Triglycerides, as the former has been extensively used for targeting anti-cancer drugs at proliferating cells through lymphatic route. Therefore this review tries to reflect the usefulness of lipid based drug carriers systems (viz. liposome, solid lipid nanoparticle, nano-lipid carriers, self-emulsifying, lipidic pro-drugs) in targeting lymphatic system and overcoming issues related to solubility and permeability of anti-cancer drugs. Moreover, we have also tried to reflect how critically lipid based carriers are important in maximizing therapeutic safety and efficacy of anti-cancer drugs.

Characterization and targeting ability evaluation of cell-penetrating peptide LyP-1 modified alginate-based nanoparticles

Doxorubicin hydrochloride (DOX) shows a powerful treatment effect on breast cancer. However, for its indiscriminate distribution after systemic administration, the therapeutic response of DOX will reduce and even result in serious adverse reactions during the long-term administration. To achieve better treatment, in this study we established a non-condensing sodium alginate-based nanoparticle-encapsulated DOX (DOX/NP), the surface of which was modified with cell-penetrating peptide LyP-1 (namely LyP-1-DOX/NP) to attain active targeting towards breast cancer cells. The size of LyP-1-DOX/NP was 138.50 ± 4.65 nm, with a polydispersity index (PDI) of 0.22 ± 0.02, and the zeta potential was 18.60 ± 0.49 mV. The drug loading efficiency (DLE) for the preparation was 91.21 ± 2.01%, with an encapsulation efficiency (EE) of 12.37 ± 0.35%. The nanoparticles exhibited good stability in vitro and slower release trend compared with free DOX in PBS at pH7.4. In vitro cytopharmacodynamics showed that LyP-1-DOX/NP had an excellent anti-breast cancer effect against MDA-MB-231 cells by the MTT test. The uptake amount of LyP-1-DOX/NP by MDA-MB-231 cells was much higher than that of free DOX or unmodified DOX/NP at all time points. Further in vivo pharmacokinetics studies showed that the concentration of LyP-1-DOX/NP was higher than that of free DOX or DOX/NP both in plasma and in tumor, suggesting its favorable long circulation and enhancing targeting property. The present study provides a promising strategy for using the LyP-1 cell-penetrating peptide to modify nanoparticles for enhancing their targeting ability towards breast cancer.

Doxorubicin hydrochloride (DOX) shows a powerful treatment effect on breast cancer.

Recent progress in LyP-1-based strategies for targeted imaging and therapy

The identification of markers expressed by pathological cells or their microenvironment would help to distinguish such cells from the normal tissues. The strategies derived from this theory can be a promising modality for imaging and treating diseases. LyP-1, a tumor homing peptide, can selectively bind to its receptor p32 protein overexpressed in various tumor-associated cells and atherosclerotic plaque macrophages. During recent decades, multiple types of LyP-1-based imaging probes and drug delivery systems have been designed and developed for diagnostic and therapeutic applications. This review first introduces LyP-1 and its receptor p32, as well as its homing, internalization and proapoptotic properties. Next, we highlight recent studies focusing on the applications of LyP-1-based strategies in the diagnosis and treatment of tumors, metastatic lesions, and atherosclerotic plaques. Finally, several limitations in the clinical translation of LyP-1-based bioconjugates are summarized.

Efficacy of a novel LyP-1-containing self-microemulsifying drug delivery system (SMEDDS) for active targeting to breast cancer

An ideal cancer therapy targets the tumor cells selectively without damaging healthy tissues. Even though the tumor-specific markers are limited, these molecules can be used for the delivery of anti-cancer drugs as an active targeting strategy. Since the lymphatic system plays a critical role in the dissemination of cancer cells, the drugs directed through lymphatics can feasibly reach to the sites of metastasis. LyP-1 is a peptide that binds to the p32 receptor which is highly expressed not only on the lymphatic endothelium but also on the malignant cells; thus, making this peptide ligand a preferable candidate to mediate active targeting of lymphatics and cancer cells. In this study, different formulations of LyP-1 containing lipid-based nanopharmaceutics so-called self-microemulsifying drug delivery systems (SMEDDS) were developed and tested for their efficacy in targeting breast cancer. Following the selection of non-toxic formulation, doxorubicin hydrochloride and LyP-1 were co-administered in the SMEDDS, which resulted in a significant increase in in vitro cytotoxicity in p32-expressing breast cancer cells, 4T1 and MDA-MB-231. Accordingly, the uptake of LyP-1 in the SMEDDS by the cancer cells was demonstrated. The expression of p32 was detected in the 4T1 tumor tissues which were efficiently targeted with LyP-1 in the SMEDDS. When doxorubicin was co-administrated with LyP-1 in SMEDDS via intraperitonial administration, tumor growth and metastasis were significantly reduced. In conclusion, a novel and efficacious SMEDDS formulation containing LyP-1 with a droplet size less than 100 nm was developed for the lymphatic targeting of breast cancer.

Novel Drug Delivery Approach via Self-Microemulsifying Drug Delivery System for Enhancing Oral Bioavailability of Asenapine Maleate: Optimization, Characterization, Cell Uptake, and In Vivo Pharmacokinetic Studies

Asenapine maleate (AM)-loaded self-microemulsifying drug delivery system (AM-SMEDDS) was prepared to increase its oral bioavailability. AM-SMEDDS was developed using Capryol 90, Cremophor EL, and Transcutol HP as oil, surfactant, and cosurfactant, respectively, by spontaneous emulsification method. Pseudoternary diagram showed maximum region at 3:1 ratio of Cremophor EL/Transcutol HP. The AM-SMEDDS showed globule size and zeta potential of 21.1 ± 1.2 nm and - 19.3 ± 1.8 mV, respectively. Globules were found to be of spherical shape and uniformly distributed by transmission electron microscopy. In vitro drug release study showed 99.2 ± 3.3% of drug release at the end of 8 h in phosphate buffer pH 6.8. Ex vivo drug release study showed only 15% of drug diffusion through stomach and ~ 85% drug was diffused through intestinal membrane. Confocal and flow cytometry study showed that cellular uptake of coumarin-6 loaded SMEDDS was significantly enhanced by Caco-2 cells as that of coumarin-6 solution. The relative bioavailability of AM-SMEDDS was found to be 23.53 times greater than AM suspension. Intestinal lymphatic transport study using Cycloheximide (CHX) showed that the AUC_total of AM-SMEDDS reduced about 35.67% compared with that without the treatment of CHX indicating involvement of lymphatic system in intestinal absorption of AM-loaded SMEDDS. These findings demonstrated the potential of SMEDDS for oral bioavailability improvement of AM via lymphatic uptake. Graphical Abstract.

Self-microemulsifying Drug Delivery System for Problematic Molecules: An Update

BACKGROUND

The poor bioavailability of a problematic molecule is predominantly due to its high lipophilicity, low solubility in gastric fluids and/or high fist pass metabolism. Self microemulsifying drug delivery system (SMEDDS), a lipidic type IV nano-formulation has been of interest in the field of pharmaceutical research due to its potential for tailoring the physicochemical properties of pharmaceutical molecules.

METHODS

This review provides insights on various recent innovations and reports from the past seven years (2012-2019) of self-emulsifying formulations for the delivery of various types of poorly soluble drugs, phytoconstituents and high molecular peptides and gives exhaustive details of the outcome of the endeavors in this field.

RESULTS

Various types of innovative formulations have been molded from SMEDDS like selfemulsifying powders, granules, tablets, pellets, eutectic and cationic formulations. Till date, many research reports and patents have been filed on self-emulsifying dosage forms and many formulations have gained US-FDA approvals which are summarized in the review article.

CONCLUSION

This review content highlighted the increasing scope of SMEDDS in augmenting the physiochemical properties of an API, the variegated formulation types and the attributes of API that can be improved by SMEDD based formulations.

Paclitaxel-loaded TPGS enriched self-emulsifying carrier causes apoptosis by modulating survivin expression and inhibits tumour growth in syngeneic mammary tumours

Paclitaxel (PTX) in its commercial products exhibits adverse effects owing to excipients and also has poor oral bioavailability. Present work is directed towards development of tocopheryl polyethylene glycol succinate-assisted self-nanoemulsifying system (SEDDS) for oral delivery of PTX. Box-Behnken design of experiment was employed to optimize PTX-SEDDS and was characterized for droplet size (29.76 ± 2.64 nm), zeta potential (-21.46 ± 2.52 mV), PDI (0.177 ± 0.012), drug content (4.97 ± 0.98 mg), entrapment efficiency (98.33 ± 0.54%) and in vitro drug release (51.03 ± 2.23% PTX at 72 h). PTX-SEDDS exhibited IC₅₀; 1.58 ± 0.12 µM and a 52.46-folds higher cell uptake in MDA-MB-231 cells along with cellular and nuclear morphology changes. Significantly higher G₂M cell cycle arrest, apoptosis, mitochondrial membrane potential disruption and ROS production was exhibited by PTX-SEDDS in comparison to Taxol. Up-regulation of Bax, p21, cleaved-caspase 3, -caspase 9 and down-regulation of Bcl2 and survivin suggested apoptosis via intrinsic pathways. Pharmacokinetic study showed approximately 4-folds higher oral bioavailability of PTX-SEDDS than Taxol. Significant reduction in tumour volume and weight was observed in syngeneic mammary tumour in SD rats. Tumour histopathology and TUNEL assay showed apoptosis in tumour tissue. PTX-SEDDS caused low lung metastasis, and was safe and stable. Conclusively, PTX-SEDDS could be suitable option for oral delivery of PTX.

Molecular dynamics, thermodynamic, and mutational binding studies for tumor-specific LyP-1 in complex with p32

Recent studies in tumor homing peptides have shown the specificity of LyP-1 (CGNKRTRGC) to tumor lymphatics. In this present work, we evaluated the possible interactions between cyclic LyP-1 and its receptor, p32, with molecular dynamics and docking studies in order to lead the design of novel LyP-1 derivatives, which could bind to p32 more effectively and perform enhanced antitumor effect. The total binding enthalpy energies have been obtained by MM-PBSA thermodynamic computations and the favorability of p32.LyP-1 complex in water has been shown by explicit water MD computations. The last 30 ns of molecular dynamics trajectory have shown the strong interaction of LyP-1 with the inner surface chains of p32, especially with chains B and C. ALA-SCAN mutagenesis studies have indicated the considerable influence of Asn3, Lys4, Arg5, and Arg7 amino acid residues on the specific binding of LyP-1. Within the knowledge of the critical role of p32 receptor in cancer cell metabolism, this study can lead to further developments in anticancer therapy by targeting p32 with LyP-1 derivatives as active targeting moiety. This data can also be applied for the development of new drug delivery systems in which LyP-1 can be used for its targeting and anticancer properties.

From amino acid sequence to bioactivity: The biomedical potential of antitumor peptides

Chemoprevention is the use of natural and/or synthetic substances to block, reverse, or retard the process of carcinogenesis. In this field, the use of antitumor peptides is of interest as, (i) these molecules are small in size, (ii) they show good cell diffusion and permeability, (iii) they affect one or more specific molecular pathways involved in carcinogenesis, and (iv) they are not usually genotoxic. We have checked the Web of Science Database (23/11/2015) in order to collect papers reporting on bioactive peptide (1691 registers), which was further filtered searching terms such as "antiproliferative," "antitumoral," or "apoptosis" among others. Works reporting the amino acid sequence of an antiproliferative peptide were kept (60 registers), and this was complemented with the peptides included in CancerPPD, an extensive resource for antiproliferative peptides and proteins. Peptides were grouped according to one of the following mechanism of action: inhibition of cell migration, inhibition of tumor angiogenesis, antioxidative mechanisms, inhibition of gene transcription/cell proliferation, induction of apoptosis, disorganization of tubulin structure, cytotoxicity, or unknown mechanisms. The main mechanisms of action of those antiproliferative peptides with known amino acid sequences are presented and finally, their potential clinical usefulness and future challenges on their application is discussed.

Mono-guanidine heterolipid based SMEDDS: A promising tool for cytosolic delivery of antineoplastics

In the present work, we designed and synthesized a novel mono-guanidine heterolipid (MGH) and confirmed its structure by NMR and ESI-MS. The MGH was used as cationic lipid in developing etoposide loaded cationic self-microemulsifying drug delivery system (ECS) intended to be delivered by intratumoral route. The ECS exhibited size <50 nm and zeta potential +32.6 mV on dilution with various isotonic vehicles with no phase separation or drug precipitation. The ECS could be easily sterilized by membrane filtration method and showed excellent stability for 6 months. The ECS demonstrated excellent in vitro antiproliferative activity against B16F10 cells which is attributed to its high transfection efficiency and capability to cause prolonged drug release in cytosolic space. In vivo antitumor activity of ECS was conducted in B16F10 induced melanoma tumor model. ECS at 12 mg/kg dose showed superior tumor suppression ability and exhibited 100% survival compared to other formulations. Mice treated with ECS by intratumoral route, showed neither systemic side effect nor any evidences of hepatotoxicity and nephrotoxicity. In contrast, etoposide administered by intravenous route showed remarkable systemic toxicity, hepatotoxicity and nephrotoxicity.

Recent approaches of lipid-based delivery system for lymphatic targeting via oral route

Lymphatic system is a key target in research field due to its distinctive makeup and huge contributing functions within the body. Intestinal lymphatic drug transport (chylomicron pathway) is intensely described in research field till date because it is considered to be the best for improving oral drug delivery by avoiding first pass metabolism. The lymphatic imaging techniques and potential therapeutic candidates are engaged for evaluating disease states and overcoming these conditions. The novel drug delivery systems such as self-microemulsifying drug delivery system, nanoparticles, liposomes, nano-lipid carriers, solid lipid carriers are employed for delivering drugs through lymphatic system via various routes such as subcutaneous route, intraperitoneal route, pulmonary route, gastric sub-mucosal injection, intrapleural and intradermal. Among these colloidal particles, lipid-based delivery system is considered to be the best for lymphatic delivery. From the last few decades, mesenteric lymph duct cannulation and thoracic lymph duct cannulation are followed to assess lymphatic uptake of drugs. Due to their limitations, chylomicrons inhibitors and in-vitro models are employed, i.e. lipolysis model and permeability model. Currently, research on this topic still continues and drainage system used to deliver the drugs against lymphatic disease as well as targeting other organs by modulating the chylomicron pathway.