Evaluation of Tributyrin Lipid Emulsion with Affinity to Low-Density Lipoprotein: Pharmacokinetics in Adult Male Wistar Rats and Cellular Activity on Caco-2 and HepG2 Cell Lines

Formulating 10-hydroxycamptothecin into nanoemulsion with functional excipient tributyrin: An innovative strategy for targeted hepatic cancer chemotherapy

This study aimed to develop an innovative dosage form for 10-hydroxycamptothecin (HCPT), a chemotherapeutic agent with limited aqueous solubility and stability, to enhance its parenteral delivery and targeting to hepatic cancer. We formulated HCPT into a nanoemulsion using tributyrin, a dietary component with histone deacetylase inhibitor activity. The resulting HCPT-loaded tributyrin nanoemulsion (Tri-HCPT-E) underwent extensive evaluations. Tri-HCPT-E significantly improved the aqueous solubility, stability, and anti-cancer activities in HepG2 cells. Pharmacokinetic studies confirmed the increased stability and hepatic targeting, with Tri-HCPT-E leading to a 120-fold increase in plasma exposure of intact HCPT and a 10-fold increase in hepatic exposure compared to the commercial free solution. Co-administration of 17α-ethynylestradiol, an up-regulator of low-density lipoprotein (LDL) receptor, further enhanced the distribution and metabolism of HCPT, demonstrating an association between the LDL receptor pathway and hepatic targeting. Most importantly, Tri-HCPT-E exhibited superior in vivo anti-cancer efficacy in a mouse xenograft model compared to the commercial formulation, without causing escalated hepatic or renal toxicity. In conclusion, formulating HCPT into a nanoemulsion with tributyrin has proven to be an innovative and effective strategy for targeted hepatic cancer chemotherapy while tributyrin, a pharmacologically active dietary component, has emerged as a promising functional excipient for drug delivery.

Harnessing and delivering microbial metabolites as therapeutics via advanced pharmaceutical approaches

Microbial metabolites have emerged as key players in the interplay between diet, the gut microbiome, and host health. Two major classes, short-chain fatty acids (SCFAs) and tryptophan (Trp) metabolites, are recognized to regulate inflammatory, immune, and metabolic responses within the host. Given that many human diseases are associated with dysbiosis of the gut microbiome and consequent reductions in microbial metabolite production, the administration of these metabolites represents a direct, multi-targeted treatment. While a multitude of preclinical studies showcase the therapeutic potential of both SCFAs and Trp metabolites, they often rely on high doses and frequent dosing regimens to achieve systemic effects, thereby constraining their clinical applicability. To address these limitations, a variety of pharmaceutical formulations approaches that enable targeted, delayed, and/or sustained microbial metabolite delivery have been developed. These approaches, including enteric encapsulations, esterification to dietary fiber, prodrugs, and nanoformulations, pave the way for the next generation of microbial metabolite-based therapeutics. In this review, we first provide an overview of the roles of microbial metabolites in maintaining host homeostasis and outline how compromised metabolite production contributes to the pathogenesis of inflammatory, metabolic, autoimmune, allergic, infectious, and cancerous diseases. Additionally, we explore the therapeutic potential of metabolites in these disease contexts. Then, we provide a comprehensive and up-to-date review of the pharmaceutical strategies that have been employed to enhance the therapeutic efficacy of microbial metabolites, with a focus on SCFAs and Trp metabolites.

In Silico Docking of Alkylphosphocholine Analogs to Human Serum Albumin Predicts Partitioning and Pharmacokinetics

Alkylphosphocholine (APC) analogs are a novel class of broad-spectrum tumor-targeting agents that can be used for both diagnosis and treatment of cancer. The potential for clinical translation for APC analogs will strongly depend on their pharmacokinetic (PK) profiles. The aim of this work was to understand how the chemical structures of various APC analogs impact binding and PK. To achieve this aim, we performed in silico docking analysis, in vitro and in vivo partitioning experiments, and in vivo PK studies. Our results have identified 7 potential high-affinity binding sites of these compounds on human serum albumin (HSA) and suggest that the size of the functional group directly influences the albumin binding, partitioning, and PK. Namely, the bulkier the functional groups, the weaker the agent binds to albumin, the more the agent partitions onto lipoproteins, and the less time the agent spends in circulation. The results of these experiments provide novel molecular insights into the binding, partitioning, and PK of this class of compounds and similar molecules as well as suggest pharmacological strategies to alter their PK profiles. Importantly, our methodology may provide a way to design better drugs by better characterizing the PK profile for lead compound optimization.

Monobutyrin Reduces Liver Cholesterol and Improves Intestinal Barrier Function in Rats Fed High-Fat Diets

Butyric acid has been shown to reduce high-fat diet-related metabolic disturbances and to improve intestinal barrier function due to its potent anti-inflammatory capacity. This study investigates whether a butyric acid ester, monobutyrin (MB) affects lipid profiles and gut barrier function in a dose-response manner in rats fed butter- or lard-based high-fat diets. Four-week-old male Wistar rats were fed butter-based diets containing 0, 0.25, 0.75 and 1.5 MB g/100 g (dry weight basis) or 0.5 glycerol g/100 g, and diets with lard (La) containing 0 and 0.5 MB g/100 g or a low-fat control diet for 3⁻4 weeks. Lipid profiles in blood and liver tissue, intestinal permeability and cecal short-chain fatty acids were examined. The results showed a dose-dependent decrease in liver total cholesterol for 1.5 MB (p < 0.05) and liver triglycerides for 0.75 MB (p < 0.05) and 1.5 MB (p = 0.08) groups compared to the high-fat control group. Furthermore, a lower excretion of mannitol in urine in the 1.5 MB group indicated improved intestinal barrier function. When MB was supplemented in the lard-based diet, serum total cholesterol levels decreased, and total amount of liver high-density lipoprotein-cholesterol increased. Thus, MB dietary supplementation can be effective in counteracting lipid metabolism disturbances and impaired gut barrier function induced by high-fat diets.

Dietary Tributyrin Supplementation Attenuates Insulin Resistance and Abnormal Lipid Metabolism in Suckling Piglets with Intrauterine Growth Retardation

Intrauterine growth retardation (IUGR) is associated with insulin resistance and lipid disorder. Tributyrin (TB), a pro-drug of butyrate, can attenuate dysfunctions in body metabolism. In this study, we investigated the effects of TB supplementation on insulin resistance and lipid metabolism in neonatal piglets with IUGR. Eight neonatal piglets with normal birth weight (NBW) and 16 neonatal piglets with IUGR were selected, weaned on the 7th day, and fed basic milk diets (NBW and IUGR groups) or basic milk diets supplemented with 0.1% tributyrin (IT group, IUGR piglets) until day 21 (n = 8). Relative parameters for lipid metabolism and mRNA expression were measured. Piglets with IUGR showed higher (P < 0.05) concentrations of insulin in the serum, higher (P < 0.05) HOMA-IR and total cholesterol, triglycerides (TG), non-esterified fatty acid (NEFA) in the liver, and lower (P < 0.05) enzyme activities (hepatic lipase [HL], lipoprotein lipase [LPL], total lipase [TL]) and concentration of glycogen in the liver than the NBW group. TB supplementation decreased (P < 0.05) the concentrations of insulin, HOMA-IR, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol in the serum, and the concentrations of TG and NEFA in the liver, and increased (P < 0.05) enzyme activities (HL, LPL, and TL) and concentration of glycogen in the liver of the IT group. The mRNA expression for insulin signal transduction pathway and hepatic lipogenic pathway (including transcription factors and nuclear factors) was significantly (P < 0.05) affected in the liver by IUGR, which was efficiently (P < 0.05) attenuated by diets supplemented with TB. TB supplementation has therapeutic potential for attenuating insulin resistance and abnormal lipid metabolism in IUGR piglets by increasing enzyme activities and upregulating mRNA expression, leading to an early improvement in the metabolic efficiency of IUGR piglets.

The chemopreventive activity of the histone deacetylase inhibitor tributyrin in colon carcinogenesis involves the induction of apoptosis and reduction of DNA damage

The chemopreventive activity of the histone deacetylase inhibitor (HDACi) tributyrin (TB), a prodrug of butyric acid (BA), was evaluated in a rat model of colon carcinogenesis. The animals were treated with TB (TB group: 200mg/100g of body weight, b.w.) or maltodextrin (MD isocaloric control group: 300 mg/100g b.w.) daily for 9 consecutive weeks. In the 3rd and 4th weeks of treatment, the rats in the TB and MD groups were given DMH (40 mg/kg b.w.) twice a week. After 9 weeks, the animals were euthanized, and the distal colon was examined. Compared with the control group (MD group), TB treatment reduced the total number of aberrant crypt foci (ACF; p<0.05) as well as the ACF with ≥4 crypts (p<0.05), which are considered more aggressive, but not inhibited the formation of DMH-induced O6-methyldeoxyguanosine DNA adducts. The TB group also showed a higher apoptotic index (p<0.05) and reduced DNA damage (p<0.05) compared with MD group. TB acted as a HDACi, as rats treated with the prodrug of BA had higher levels of histone H3K9 acetylation compared with the MD group (p<0.05). TB administration resulted in increased colonic tissue concentrations of BA (p<0.05) compared with the control animals. These results suggest that TB can be considered a promising chemopreventive agent for colon carcinogenesis because it reduced the number of ACF, including those that were more aggressive. Induction of apoptosis and reduction of DNA damage are cellular mechanisms that appear to be involved in the chemopreventive activity of TB.

Oral administration of tributyrin increases concentration of butyrate in the portal vein and prevents lipopolysaccharide-induced liver injury in rats

BACKGROUND & AIMS

Short-chain fatty acids, especially butyrate, have various biological activities including inhibition of tumor necrosis factor (TNF)-α secretion, via attenuation of nuclear factor-κB (NF-κB) activation. Here, we evaluated the protective effect of oral administration of tributyrin, a prodrug of butyrate, on lipopolysaccharide (LPS)-induced liver injury in rats.

METHODS

Rats were divided into four groups: normal control, tributyrin, LPS, and tributyrin/LPS (treated with tributyrin 1 h before LPS). Plasma levels of butyrate and TNF-α, expression of TNF-α, NF-κB, Toll-like receptor (TLR) 2, and TLR4 mRNA in liver, blood biochemical tests, and histopathological analysis of liver were performed.

RESULTS

Oral tributyrin increased plasma butyrate level in the portal vein to 2.4 mM at 1 h and 0.7 mM at 2.5 h. Tributyrin attenuated NF-κB activation and liver tissue injury associated with LPS injection. The increases in TNF-α level, and hepatic TLR2 mRNA expression were lower in the tributyrin/LPS group. We believe that this study provides the first evidence that orally administered tributyrin increases butyrate level in the hepato-portal system and attenuates liver injury and subsequent inflammatory responses.

CONCLUSION

Oral tributyrin increased plasma butyrate in the portal vein and attenuated liver injury in endotoxemic rats.

Chemoprevention of rat hepatocarcinogenesis with histone deacetylase inhibitors: efficacy of tributyrin, a butyric acid prodrug

Hepatocellular carcinoma (HCC) ranks in prevalence and mortality among top 10 cancers worldwide. Butyric acid (BA), a member of histone deacetylase inhibitors (HDACi) has been proposed as an anticarcinogenic agent. However, its short half-life is a therapeutical limitation. This problem could be circumvented with tributyrin (TB), a proposed BA prodrug. To investigate TB effectiveness for chemoprevention, rats were treated with the compound during initial phases of "resistant hepatocyte" model of hepatocarcinogenesis, and cellular and molecular parameters were evaluated. TB inhibited (p < 0.05) development of hepatic preneoplastic lesions (PNL) including persistent ones considered HCC progression sites. TB increased (p < 0.05) PNL remodeling, a process whereby they tend to disappear. TB did not inhibit cell proliferation in PNL, but induced (p < 0.05) apoptosis in remodeling ones. Compared to controls, rats treated with TB presented increased (p < 0.05) hepatic levels of BA indicating its effectiveness as a prodrug. Molecular mechanisms of TB-induced hepatocarcinogenesis chemoprevention were investigated. TB increased (p < 0.05) hepatic nuclear histone H3K9 hyperacetylation specifically in PNL and p21 protein expression, which could be associated with inhibitory HDAC effects. Moreover, it reduced (p < 0.05) the frequency of persistent PNL with aberrant cytoplasmic p53 accumulation, an alteration associated with increased malignancy. Original data observed in our study support the effectiveness of TB as a prodrug of BA and as an HDACi in hepatocarcinogenesis chemoprevention. Besides histone acetylation and p21 restored expression, molecular mechanisms involved with TB anticarcinogenic actions could also be related to modulation of p53 pathways.

Evaluation of the pharmacokinetics of all-trans-retinoic acid (ATRA) in Wistar rats after intravenous administration of ATRA loaded into tributyrin submicron emulsion and its cellular activity on caco-2 and HepG2 cell lines

The pharmacokinetics of all-trans-retinoic acid (ATRA), an anti-cancer drug was highly variable due to its poor aqueous solubility. In this study, we investigated the pharmacokinetics of ATRA in male Wistar rats following intravenous administration of the ATRA loaded tributyrin emulsion. In vitro, the ATRA emulsion was proved binding to apolipoprotein(s). In vivo, the clearance of ATRA was significantly reduced by formulating into the tributyrin emulsion, leading to higher AUCs. Co-administration with 17alpha-ethynylestradiol, a compound known to upregulate the activity of low-density lipoprotein receptors in tissues, significantly increased the K(e), V, and CL of ATRA. The variation of plasma AUCs after administering the ATRA emulsion to the healthy rats was two times less than that after the ATRA solution. The IC(50) in ATRA of the ATRA emulsion for the Caco-2 carcinoma cells was 3.8 microg/mL lower than 6 microg/mL of the ATRA solution. The IC(50) of the emulsion for the HepG2 carcinoma cells was 2.8 microg/mL, while IC(50) was not achieved with the ATRA solution over the test concentration range. The finding indicated that the tributyrin emulsion could be used as a carrier for ATRA and enhances the drug effect by reducing the clearance and increasing the in vitro activity.

1-O-alkylglycerol stabilized carbamazepine intravenous o/w nanoemulsions for drug targeting in mice

Carbamazepine (CBZ) is used in the treatment of generalized tonic clonic and partial seizures. In seizure disorder the focal point of treatment is brain. At present no commercial parenteral formulation of CBZ is available. We developed o/w nanoemulsions of CBZ stabilized by 1-O-alkylglycerol/lecithin for intravenous administration and evaluated the brain targeting potential of these formulations. The nanoemulsions were characterized for globule size, zeta potential (ZP), CBZ content and in vivo tissue distribution in mice. The in vivo data revealed a significant uptake of CBZ in all tissues. Among the nanoemulsions, 1-O-decylglycerol stabilized system showed significantly higher tissue levels and availability of CBZ. Particularly for this system 2.37 times higher brain availability and a brain/serum concentration ratio of 3.0 at 30 min is an important finding. This indicates the brain targeting potential. A systematic formulation development of CBZ nanoemulsions employing 1-O-alkylglycerols might pave way to achieve selective brain delivery of this important antiepileptic drug.

Pharmacokinetics and metabolism of ligustilide, a major bioactive component in Rhizoma Chuanxiong, in the rat

Ligustilide is the most abundant bioactive ingredient in Rhizoma Chuanxiong, a Chinese medicinal herb commonly used for the treatment of cardiovascular ailments. The present study reported, for the first time, the pharmacokinetics of ligustilide, administered in its pure form and in an herbal extract, in rats. After i.v. administration of pure ligustilide, it was distributed extensively (V(d), 3.76 +/- 1.23 l/kg) and eliminated rapidly (t(1/2), 0.31 +/- 0.12 h). The i.v. clearance (CL) of ligustilide after Chuanxiong extract administration was significantly higher than that dosed in its pure form [CL, 20.35 +/- 3.05 versus 9.14 +/- 1.27 l/h/kg, p < 0.01; area under the curve (AUC), 0.79 +/- 0.10 versus 1.81 +/- 0.24 mg x h/l, p < 0.01], suggesting significant interaction between ligustilide and components present in the extract. Dose-dependent pharmacokinetics was observed after i.p. administration, and a significantly higher dose-normalized AUC (1.77 +/- 0.23 mg x h/l) at 52 mg/kg was obtained than that at 26 mg/kg (0.93 +/- 0.07 mg x h/l, p < 0.05). Oral bioavailability of ligustilide was low (2.6%), which was partly because of extensive first-pass metabolism in the liver. Seven metabolites of ligustilide were identified, and three of them were unequivocally characterized as butylidenephthalide, senkyunolide I, and senkyunolide H. These three compounds also occurred naturally in the herb and were reported to be bioactive.

Low Oral Bioavailability and Pharmacokinetics of Senkyunolide A, a Major Bioactive Component in Rhizoma Chuanxiong, in the Rat

The pharmacokinetics of senkyunolide A, one of the major bioactive ingredients in the traditional Chinese medicinal herb Rhizoma Chuanxiong, which is commonly used for the treatment of cardiovascular diseases, was studied in rats. After intravenous (IV) administration, senkyunolide A was extensively distributed (Vd/F: 6.74 +/- 0.73 L/kg) and rapidly eliminated from the plasma (CL/F: 7.20 +/- 0.48 L/h per kilogram and t1/2: 0.65 +/- 0.06 hr). Hepatic metabolism was suggested as the major route of senkyunolide A elimination as indicated by the results of in vitro S9 fraction study. After intraperitoneal (IP) administration, senkyunolide A exhibited dose-independent pharmacokinetics. The absorption after IP administration was rapid (Tmax: 0.04 +/- 0.01 hours), and the bioavailability was 75%. After oral administration, senkyunolide A was also absorbed rapidly (Tmax: 0.21 +/- 0.08 hours); however, its oral bioavailability was low (approximately 8%). The contributing factors were determined to be instability in the gastrointestinal tract (accounting for 67% of the loss) and hepatic first-pass metabolism (accounting for another 25%). Pharmacokinetics of senkyunolide A were unaltered when Chuanxiong extract was administered, which suggests that components in the extract have insignificant effects on senkyunolide A pharmacokinetics.