Yong-Hong Liao

Hyaluronan: Pharmaceutical Characterization and Drug Delivery

Hyaluronic acid (HA), is a polyanionic polysaccharide that consists of N-acetyl-D-glucosamine and β-glucoronic acid. It is most frequently referred to as hyaluronan because it exists in vivo as a polyanion and not in the protonated acid form. HA is distributed widely in vertebrates and presents as a component of the cell coat of many strains of bacteria. Initially the main functions of HA were believed to be mechanical as it has a protective, structure stabilizing and shock-absorbing role in the body. However, more recently the role of HA in the mediation of physiological functions via interaction with binding proteins and cell surface receptors including morphogenesis, regeneration, wound healing, and tumor invasion, as well as in the dynamic regulation of such interactions on cell signaling and behavior has been documented. The unique viscoelastic nature of hyaluronan along with its biocompatibility and nonimmunogenicity has led to its use in a number of cosmetic, medical, and pharmaceutical applications. More recently, HA has been investigated as a drug delivery agent for ophthalmic, nasal, pulmonary, parenteral, and dermal routes. The purpose of our review is to describe the physical, chemical, and biological properties of native HA together with how it can be produced and assayed along with a detailed analysis of its medical and pharmaceutical applications.

Effects of Sucrose and Trehalose on the Preservation of the Native Structure of Spray-Dried Lysozyme

AbstractPurpose. To investigate the effects of sucrose, trehalose, sucrose/dextran mixtures, and sucrose/trehalose mixtures on the preservation of the native structure of spray-dried lysozyme in the solid state. Methods. The intensity of the α-helical band and the melting enthalpies (ΔHm ) of spray-dried lysozyme in the dried form and in aqueous solution were obtained using second derivative FTIR and differential scanning calorimetry (DSC) respectively. Results. The intensity of the Δ-helical band and the ΔH m of spray-dried lysozyme obtained were linearly correlated and both suggest that the stabilization of lysozyme in the dried form was excipient concentration-dependent with a close to maximum stabilization being conferred by sucrose or trehalose at a mass ratio 1–2 (sugar:enzyme). Sucrose appeared to be more effective than trehalose on a weight by weight basis whilst stabilizing effects of dextran/sucrose or trehalose/sucrose mixtures were found to be additive. Conclusion. Dehydration during spray drying was considered the main stress to the denaturation of lysozyme. A major effect of the sugars in protecting lysozyme against dehydration was attributable to hydrogen bonding between the sugar and protein molecules, which lead to an increase in the change in the negative value of the free energy between native and denatured states.

Protective mechanism of stabilizing excipients against dehydration in the freeze-drying of proteins.

AbstractPurpose. To investigate the influence of type and amount of excipient on the preservation of the native structure and the biologic activity of freeze-dried lysozyme and catalase. Methods. The secondary structure of protein in the dried form and in aqueous solution was obtained using second derivative infrared spectroscopy and circular dichroism spectra respectively whilst the activity was determined using bioassay. Results. Small molecular excipients (glycerol, sorbitol, 1,6-anhydroglucose, sucrose, and trehalose) were found to stabilize the activity and/or the native structure of freeze-dried lysozyme and catalase, despite the processing temperatures being above Tg′ of excipient-protein mixtures. The preservation of catalase activity required excipient to be present at a lower excipient to enzyme mass ratio than that necessary to preserve native structure in the dried form. Combining dextran with sucrose synergistically protected the native structure of catalase but preserved the activity in an additive manner. Conclusion. The results indicate that the stabilization of catalase and lysozyme by excipients during dehydration was mainly due to water substitution rather than the formation of glass; the latter appearing not to be a prerequisite during freeze-drying.

An LC–MS/MS method for the simultaneous determination of chlorogenic acid, forsythiaside A and baicalin in rat plasma and its application to pharmacokinetic study of Shuang-huang-lian in rats

An LC-MS/MS method was developed for the simultaneous determination of chlorogenic acid, forsythiaside A and baicalin, three major ingredients in Shuang-huang-lian preparations, in rat plasma. Following extraction by methanol-ethyl acetate-trifluoroacetic acid (49:49:2, v/v/v), the extracted analytes were separated on a reverse phase C12 column using a gradient mobile phase system of acetonitrile-water containing 0.1% formic acid. The limits of quantification were between 1.0 and 2.1ng/mL, the precision was <7% and the accuracy was between 94% and 107%. The validated method was applied to a comparative pharmacokinetic study in rats after administration of Shuang-huang-lian solutions via intravenous, peroral or intratracheal routes. The results showed that the three chemical markers were more rapidly and thoroughly absorbed following pulmonary delivery as compared with peroral administration.

Turbidimetric and HPLC assays for the determination of formulated lysozyme activity

In several studies lysozyme has been employed as a model protein to investigate the effects of formulation factors upon biological activity. The aim of this work was to develop and validate an HPLC technique to assay lysozyme and to compare the results with biological activity determined from a validated turbidimetric assay. The turbidimetric assay was based upon the lytic action of lysozyme on Micrococcus lysodeikticus cells, whilst the reverse‐phase HPLC assay employed an acetonitrile gradient in 0.1% trifluoroacetic acid. The limits of detection and quantification were 3.84 and 6.24 μg mL−1 for HPLC assay, whilst the corresponding values for turbidimetric assay were 1.94 and 3.86 μg mL−1. The methods were used to monitor the loss of enzyme activity after heating. Lysozyme concentrations determined from HPLC peak height were found to correlate (r2 = 0.9963) with those obtained from turbidimetric assay.

Brucein D induces apoptosis in pancreatic adenocarcinoma cell line PANC-1 through the activation of p38-mitogen activated protein kinase

Pancreatic cancer is a malignant disease with extremely high mortality. Our previous work found that Brucea javanica fruit possesses potent anti-pancreatic cancer activity. In the present study, brucein D (BD), a quassinoid found abundantly in B. javanica fruit, was evaluated for its anti-proliferative and apoptogenic actions. BD inhibited the growth of three pancreatic cancer cell lines, i.e., PANC-1, SW1990 and CAPAN-1, but exerted only modest cytotoxicity on non-tumorigenic Hs68 cells. Hoechst 33342 staining and Cell Death Detection ELISA(PLUS) assay revealed that BD-induced DNA fragmentation in PANC-1 cells. Moreover, subG1 phase was observed in the BD-treated cells. Western blot experiments indicated that BD exposure augmented caspase 3, 8, 9 and bak protein levels, while attenuating the expression of bcl-2. Furthermore, BD treatment promoted phosphorylation of p38-MAPK. The selective p38-MAPK inhibitor SB203580 effectively mitigated the BD-induced apoptosis in PANC-1 cells, suggesting that p38-MAPK signaling pathway was involved in the BD-induced apoptosis in pancreatic cancer cells. Taken together, our results provide experimental evidence to support the traditional use of B. javanica fruit in cancer treatment, and render BD a promising chemical candidate for further development into anti-pancreatic cancer agent.

Amides from Piper nigrum L. with dissimilar effects on melanocyte proliferation in‐vitro

Melanocyte proliferation stimulants are of interest as potential treatments for the depigmentary skin disorder, vitiligo. Piper nigrum L. (Piperaceae) fruit (black pepper) water extract and its main alkaloid, piperine (1), promote melanocyte proliferation in‐vitro. A crude chloroform extract of P. nigrum containing piperine was more stimulatory than an equivalent concentration of the pure compound, suggesting the presence of other active components. Piperine (1), guineensine (2), pipericide (3), N‐feruloyltyramine (4) and N‐isobutyl‐2E, 4E‐dodecadienamide (5) were isolated from the chloroform extract. Their activity was compared with piperine and with commercial piperlongumine (6) and safrole (7), and synthetically prepared piperettine (8), piperlonguminine (9) and 1‐(3, 4‐methylenedioxyphenyl)‐decane (10). Compounds 6–10 either occur in P. nigrum or are structurally related. Compounds 1, 2, 3, 8 and 9 stimulated melanocyte proliferation, whereas 4, 5, 6, 7 and 10 did not. Comparison of structures suggests that the methylenedioxyphenyl function is essential for melanocyte stimulatory activity. Only those compounds also possessing an amide group were active, although the amino component of the amide group and chain linking it to the methylenedioxyphenyl group can vary. P. nigrum, therefore, contains several amides with the ability to stimulate melanocyte proliferation. This finding supports the traditional use of P. nigrum extracts in vitiligo and provides new lead compounds for drug development for this disease.

Involvement of the Inhibition of Intestinal Glucuronidation in Enhancing the Oral Bioavailability of Resveratrol by Labrasol Containing Nanoemulsions

Nanoemulsions have been developed for the oral delivery of poorly bioavailable phenolic compounds that are sensitive to intestinal glucuronidation. However, little is known about the contribution of UDP-glucuronosyltransferase (UGT) inhibitory excipients in nanoemulsions toward the inhibition of intestinal glucuronidation and the consequent enhanced bioavailability. In this study, Labrasol but not poloxamer 188 (F68) was found to inhibit the glucuronidation of resveratrol (RES), a model phenolic compound, in an inhibition assay with rat microsomes. Subsequently, two nanoemulsions, Lab-N and F68-N, were prepared with similar particle size distribution, zeta potentials, and entrapment efficiency by coemulsifying with Labrasol or F68, respectively. Although Lab-N exhibited inferior or comparable profiles of in vitro release, cellular uptake in Caco-2 cells, and lymphatic transport in rats to F68-N, the in vitro absorption study with everted sacs suggested that Labrasol containing formulations significantly and dose-dependently increased the transport of RES relative to free RES or F68-N by decreasing the amount of permeated metabolite, RES-3-glucuronide (RES-G). The in vivo pharmacokinetic experiments indicated that Lab-N exhibited increments in the maximum plasma concentration and the bioavailability of RES by 1098% and 560%, respectively, and significant decreases in those of RES-G, compared to F68-N. The overall results demonstrated that the improved oral bioavailability of RES by Lab-N was mainly attributable to the inhibition of intestinal glucuronidation by the presence of UGT inhibitory excipient.

Pulmonary delivery of scutellarin solution and mucoadhesive particles in rats.

The objectives of this study were to investigate the effects of mucoadhesive excipients on systemic bioavailability of an inhaled drug and to evaluate the feasibility of using the pulmonary route for non-invasive systemic delivery of scutellarin, a poorly orally absorbed flavonoid glucuronide. Following intratracheal spray of the scutellarin solution, the bioavailability was found to be approximately 77% in rats, which was >30-fold higher than that via the peroral route. In addition, the pulmonary absorption of scutellarin appeared to avoid the intestinal first-pass metabolism accompanied by peroral administration. Spray-dried scutellarin particles with the presence of mucoadhesive excipients were found to affect the corresponding mucociliary transport rate (MTR) as evaluated by a frog palate model. The pharmacokinetic results indicated that the magnitude of AUC(0-480) of intrapulmonary delivered drug particles was not correlated to the fine particle fraction (FPF) but inversely related to the MTR. Incorporating mucoadhesive polymeric mixtures into the scutellarin particles, the MTR decreased by sixfold, and the absolute bioavailability of the drug was found to increase from 70.1% to 97.9% despite a decrease in the FPF. Moreover, in vitro results evaluated using Calu-3 and A549 cell lines showed that scutellarin and spray-dried particles with or without the presence of mucoadhesives exhibited no local cell cytotoxic effects in the tested concentration range. In conclusion, the conducting airway is well permeable to scutellarin, and scutellarin may be effectively delivered systemically through inhalation of respirable droplets or particles.

Neuroprotective effect of water extract of Panax ginseng on corticosterone-induced apoptosis in PC12 cells and its underlying molecule mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE The root of Panax ginseng C.A. Meyer (Family Araliaceae) is an important medicinal plant which has been employed as a panacea for more than 2,000 years in China. It has the actions of invigorating primordial qi, recovering pulse and desertion, engendering liquid, and calming spirit. The water extract of Panax ginseng (WEG) has been used to treat kinds of central nervous system disorders, such as depression, insomnia, Alzheimer׳s disease and Parkinson׳s disease. Our previous work has demonstrated that WEG possessed antidepressant-like activities in both acute and chronic stress models of depression. Nevertheless, there are no studies on the cytoprotection and potential mechanisms of WEG on corticosterone-induced apoptosis. The present study focuses on cytoprotection against corticosterone-induced neurotoxicity in PC12 cells and its underlying molecule mechanisms of the antidepressant-like effect of WEG. MATERIALS AND METHODS The PC12 cells were treated with 250 μmol/L corticosterone in the absence or presence of WEG for 24h, then 3-(4,5-dimethy thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) detection, Hoechst33342 staining and TUNEL staining were investigated to confirm the neuroprotection of WEG. Then, mitochondrial permeability transition pore (mPTP), mitochondrial membrane potential (MMP), intracellular Ca(2+) ([Ca(2+)]i), reactive oxygen species (ROS) concentration, and the expression level of glucocorticoid receptor (GR), heat shock protein 90 (Hsp90), histone deactylase 6 (HDAC6), glucose-regulated protein 78 (GRP78), growth arrest and DNA damage inducible protein 153 (GADD153), X-box DNA-binding protein-1 (XBP-1), caspase-12, cytochrome C, inhibitor of caspase-activated deoxyribonuclease (ICAD), caspase-3 and caspase-9 were assessed by Western Blot analysis to understand the molecule mechanisms of neuroprotection of WEG. RESULTS WEG partly reversed corticosterone-induced damage in PC12 cells, which increased cell viability, decreased LDH release, and attenuated corticosterone-induced apoptosis as compared with the corticosterone-treated group. Mechanistically, compared with the corticosterone-treated group, WEG strongly attenuated [Ca(2+)]i overload and ROS level, and restored mitochondrial function, including mPTP and MMP. Furthermore, WEG strongly up-regulated the expression of GR and HDAC6, and down-regulated the expression of Hsp90, cytochrome C, ICAD, caspase-3, caspase-9 as well as endoplasmic reticulum (ER) stress-related proteins, such as GADD153, GRP78, XBP-1, and caspase-12. CONCLUSION WEG possessed neuroprotection against corticosterone-induced damage in PC12 cells, and the underlying molecule mechanisms was depended on the intervening of HDAC6 and HSP90 of the GR-related function proteins, and subsequent restoration of ER and mitochondria functions.