Lysophosphatidylcholine-based liposome to improve oral absorption and nephroprotective effects of astaxanthin.

BACKGROUND: The present study was aimed to develop astaxanthin (AX)-loaded liposomes by the utilization of soybean phosphatidylcholine (PC) and lysophosphatidylcholine (LPC) to improve the nutraceutical properties of AX. AX-loaded liposomes consisting of PC (PC/AX) and LPC (LPC/AX) were evaluated in terms of particle size distribution, morphology, release characteristics, pharmacokinetic behavior, and nephroprotective effects in a rat model of acute kidney injury. RESULTS: PC/AX and LPC/AX had uniform size distributions with a mean particle size of 254 and 148 nm, respectively. Under pH 6.8 conditions, both liposomes exhibited improved dissolution behavior of AX compared with crystalline AX (cAX). In particular, LPC/AX showed a sevenfold higher release of AX than PC/AX. After the oral administration of LPC/AX (33.2 mg AX kg-1 ) to rats, there was a significant increase in systemic exposure to AX, as evidenced by a 15-fold higher AUC0-24 h than PC/AX. However, the oral absorption of AX in the cAX group was negligible. Based on the results of histological analysis and measurement of plasma biomarkers, LPC/AX exhibited improved nephroprotective effects of AX in the rat model of kidney injury. CONCLUSION: From these observations, a strategic application of the LPC-based liposomal approach might be a promising option to improve the nutraceutical properties of AX. © 2022 Society of Chemical Industry.

Strategic application of liposomal system to R-α-lipoic acid for the improvement of nutraceutical properties.

R-α-lipoic acid (RLA) and dihydrolipoic acid (DHLA), a reduced form of RLA, are potent endogenous antioxidants that can reduce oxidative damage. Despite their numerous nutraceutical potentials, clinical applications of RLA are still limited due to its poor solubility and stability problems. This study aimed to develop an RLA-loaded liposome (LIP/RLA) for the improvement of nutraceutical properties. LIP/RLA was developed by a typical solvent injection method. Uniform liposomes of LIP/RLA were observed by transmission electron microscopy, and the mean particle size was calculated to be ∼150 nm from the data of dynamic light scattering. LIP/RLA could prevent the degradation of RLA even under acidic conditions (pH 1.2) possibly due to the encapsulation of RLA into the liposomal structure. In the release test under pH6.8 with lipase, LIP/RLA showed relatively rapid release of RLA, possibly due to the lipolysis of phospholipids by lipase. After the oral administration of LIP/RLA (10 mg-RLA/kg, p.o.) in rats, the systemic exposures of RLA and DHLA increased by 2.8- and 5.8-fold, respectively. In a rat model of acute hepatic injury induced by carbon tetrachloride (CCl4) (0.7 mL-CCl4/kg, p.o.), orally dosed LIP/RLA (3 mg-RLA/kg, p.o.) resulted in 78.7% and 86.4% reductions of plasma alanine aminotransferase, and aspartate aminotransferase, respectively; however, RLA was found to be less effective possibly due to the poor oral absorption. The RLA-loaded liposomal system might be a promising carrier for poorly water-soluble materials with poor stability under acidic conditions, as well as RLA, to improve their oral absorption and nutraceutical properties.

[Screening test for drugs in health foods using 2-dimensional TLC].

A simple and rapid method for screening of drugs in health foods using 2-dimensional TLC was established. The development systems were: (1) ethyl acetate/methanol/28% ammonia (85:10:5), (2) cyclohexane/toluene/diethyl amine (65:25:10), (3) methanol and (4) ethyl acetate/methanol/25% ammonia (85:10:5). System (1) and (2) were run as 2-dimensional high-performance TLC, and System (3) and (4) were run as 2-dimensional conventional TLC. Sample extracted with methanol from health foods was applied to standardized two 2-dimensional TLCs and 4 Rf values obtained from 4 development systems were compared with reference Rf values which were measured previously using standard materials. The repeatability of reference Rf values were secured by standardizing development conditions and pattern of 4 Rf values was specific for 80 drugs. Moreover, using 2-dimensional TLC enable to assign 4 Rf values to unknown substance without influence of matrix from health foods, so it was possible to determine drugs comparing 4 Rf values. This method could be applied as first screening test for prevention of health crisis occurred by drugs added to health foods illegally.

Cancer chemotherapy by liposomal 6-[12-(dimethylamino)ethyl]aminol-3-hydroxy-7H-indeno[2,1-clquinolin-7-one dihydrochloride (TAS-103), a novel anti-cancer agent.

A novel anti-tumor agent, 6-[[2-(dimethylamino)ethyl]amino]-3-hydroxy-7H-indeno[2,1-c]quinolin-7-one dihydrochloride (TAS-103), effectively inhibits both topoisomerase I and II activities. To enhance anti-tumor efficacy and to reduce the side effects of the agent, liposomalization of TAS-103 was performed. TAS-103 was effectively entrapped in liposomes by a remote-loading method, and was stable at 4 degrees C and in the presence of 50% serum. To evaluate the anti-tumor efficacy of liposomal TAS-103, the growth inhibition against Lewis lung carcinoma cells in vitro and the therapeutic efficacy against solid tumor-bearing mice in vivo were examined. Liposomal TAS-103 showed strong cytotoxic effect against Lewis lung carcinoma cells in a dose dependent manner and effectively suppressed solid tumor growth accompanying longer survival time of tumor-bearing mice in comparison with the mice treated with free TAS-103. These results suggest that liposomal TAS-103 is useful for cancer therapy.

Isolation of a novel peptide homing to tumor-derived neovasculature that suppresses tumor growth.

Novel peptides homing to angiogenic vessels were recently isolated from a phage-displayed random pentade-capeptide library, and peptides having WRP sequence showed tumor growth suppression. In this study, we observed that another novel sequence, PVVLFPLH, suppressed tumor growth in vivo. Through the study of tumor growth suppression by the 5-mer peptides derived from this sequence, we determined the epitope sequence to be LFPLH. LFPLH, but not the shuffled peptide FHLLP, suppressed the migration of vascular endothelial growth factor-stimulated human umbilical vein endothelial cells. Interestingly, growth suppression of LFPLH against the cells as well as tumor cells was not observed in vitro. Therefore LFPLH may function to induce tumor dormancy through inhibition of angiogenesis.

Anti-neovascular therapy by liposomal DPP-CNDAC targeted to angiogenic vessels.

We previously reported that liposomalized 5'-O-dipalmitoylphosphatidyl 2'-C-cyano-2'-deoxy-1-beta-D-arabino-pentofuranosylcytosine (DPP-CNDAC), a hydrophobized derivative of the novel antitumor nucleoside CNDAC, is quite useful for cancer therapy. On the other hand, for anti-neovascular therapy, we recently isolated peptides homing to angiogenic vessels from a phage-displayed random peptide library, and observed that peptide-modified liposomal adriamycin strongly suppressed tumor growth, perhaps through damaging angiogenic endothelial cells. In the present study, we modified DPP-CNDAC-liposomes with one of the angiogenic homing peptides, APRPG, and examined their antitumor activity. Three doses of APRPG-modified DPP-CNDAC-liposomes (15 mg/kg as CNDAC) strongly inhibited tumor growth compared with the same number of doses of unmodified DPP-CNDAC-liposomes. The life span was increased 31.8%, with one completely cured mouse out of the six mice treated. Since the accumulation of liposomes in the tumor tissue was not so much different between APRPG-liposomes and non-modified liposomes, the enhanced therapeutic efficacy may be explained as the alteration of targets, i.e. APRPG-modified DPP-CNDAC-liposomes caused tumor growth suppression through damage of angiogenic endothelial cells. Anti-neovascular therapy promises no drug resistance, and should be effective against essentially any kind of solid tumor; and thus the present results demonstrate another benefit of the therapy, namely, high efficacy of cancer treatment.

Anti-neovascular therapy using novel peptides homing to angiogenic vessels.

Cancer chemotherapy targeted to angiogenic vessels is expected to cause indirect tumor regression through the damage of the neovasculature without the induction of drug resistance. To develop a tool for neovasculature-specific drug delivery, we isolated novel peptides homing to angiogenic vessels formed by a dorsal air sac method from a phage-displayed peptide library. Three distinct phage clones that markedly accumulated in murine tumor xenografts presented PRPGAPLAGSWPGTS-, DRWRPALPVVLFPLH- or ASSSYPLIHWRPWAR-peptide respectively. After the determination of the epitope sequences of these peptides, we modified liposomes with epitope penta-peptides. Liposome modified with APRPG-peptide showed high accumulation in murine tumor xenografts, and APRPG-modified liposome encapsulating adriamycin effectively suppressed experimental tumor growth. Finally, specific binding of APRPG-modified liposome to human umbilical endothelial cells, and that of PRP-containing peptide to angiogenic vessels in human tumors, i.e., islet cell tumor and glioblastoma, were demonstrated. The present study indicates the usefulness of APRPG-peptide as a tool for anti-neovascular therapy, a novel modality of cancer treatment.

Suppression of tumor growth by novel peptides homing to tumor-derived new blood vessels.

Novel peptides homing to angiogenic vessels were recently isolated from a phage-displayed random pentadecapeptide library. One of the isolated peptides, ASSSYPLIHWRPWAR, significantly suppressed the migration of VEGF-stimulated human umbilical vein endothelial cells. Dendoric ASSSYPLIHWRPWAR-peptide suppressed the formation of new blood vessels in dorsal air sac model mice. Furthermore, ASSSYPLIHWRPWAR-peptide and the fragment peptides containing WRP, which is revealed to be an epitope sequence, significantly suppressed the tumor growth, although 15-mer shuffled peptide derived from ASSSYPLIHWRPWAR and pentapeptides with alanine substitution of each residue of WRP did not. Taken together, ASSSYPLIHWRPWAR-peptide may cause tumor dormancy through inhibition of angiogenesis, and the WRP sequence may be the minimal and essential sequence for this activity.