Simultaneous determination of intestinal permeability and potential drug interactions of complex mixtures using Caco-2 cells and high-resolution mass spectrometry: Studies with Rauwolfia serpentina extract

Assessment of intestinal absorption of five cannabinoids from an ethanolic CBD-rich hemp extract using Caco-2 cells in vitro

Cannabinoids are highly lipophilic constituents of the hemp plant, which is present in several products intended for consumption. While cannabidiol (CBD) effects to humans have been extensively investigated, there is limited information on other minor cannabinoids. CBD oral bioavailability is low but increases with food and high-fat intake. We used Caco-2 cells in vitro to assess intestinal absorption of five cannabinoids (CBD, CBC, CBG, CBN, and CBDV) present in a CBD-rich hemp extract. We used a fed-state simulated intestinal fluid (Fessif) for dissolution of cannabinoids. Cannabinoids did not alter Caco-2 monolayer integrity. Except for CBC, recovery of cannabinoids decreased significantly after 90-minute incubation, compared to 60-minute incubation. No measurable cannabinoids were identified in the bottom chambers. Recovery of CBD, CBC, CBG and CBN after incubation with hemp extract or cannabinoid mix containing 30 μM CBD was unchanged, but CBDV recovery decreased. With hemp extract or a mix containing 10 μM CBD, recovery of CBD and CBC did not change, CBG recovery was lower (80-82 %), and CBN and CBDV were unquantifiable. This study highlights the challenges of evaluating permeability of cannabinoids by Caco-2 cells to predict intestinal absorption, including the physicochemical properties of these compounds, incubation time and cell properties.

Formulation, Characterization and Permeability Studies of Fenugreek (Trigonella foenum-graecum) Containing Self-Emulsifying Drug Delivery System (SEDDS)

Fenugreek is used as a spice and a traditional herbal medicine for a variety of purposes, given its antidiabetic and antioxidant effects. Self-emulsifying drug delivery systems (SEDDS) of herbal drugs are targets of extensive research aiming to increase bioavailability and stability. The study’s objective was to formulate SEDDS containing Trigonella foenum-graecum extract to improve the stability of herbal extract and to increase their permeability through a Caco-2 monolayer. A characterized fenugreek dry extract was used for the formulations, while the SEDDS properties were examined by particle size analysis and zeta potential measurements. Permeability assays were carried out on Caco-2 cell monolayers, the integrity of which was monitored by follow-up trans-epithelial electric resistance measurements (TEER). Cytocompatibility was tested by the MTT method, and an indirect dissolution test was performed, using DPPH antioxidant reagent. Two different SEDDS compositions were formulated from a standardized fenugreek dry extract at either the micro- or the nanoemulsion scale with sufficient stability, enhanced bioavailability of the compounds, and sustained release from HPMC capsules. Based on our results, a modern, non-toxic, cytocompatible fenugreek SEDDS formulation with high antioxidant capacity was developed in order to improve the permeability and bioavailability of all components.

Network Pharmacology-Based Investigation of the Therapeutic Mechanisms of Action of Danning Tablets in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a rising global public health concern due to its prevalence. Danning Tablets (DNt), a composite prescription of Chinese herbal medicine, shows significant curative effects on NAFLD in clinical application. This study aimed to decipher the bioactive substances and potential mechanisms of action of DNt in the treatment of NAFLD, applying an integrated network pharmacology approach. First, the bioactive compounds of DNt were screened based on their pharmacokinetic properties, and the corresponding drug targets were predicted. Then, the NAFLD-related targets were collected. The overlapping targets between the putative targets of DNt and NAFLD-related targets were identified as the potential therapeutic targets of DNt against NAFLD. Subsequently, the networks were constructed and analyzed, and the key bioactive compounds and targets were screened out depending on their importance in the networks. Functional enrichment analysis was carried out to elucidate the potential mechanisms of DNt acting on NAFLD. Finally, a molecular docking simulation was implemented to assess the potential binding affinity between the key targets and the bioactive compounds. As a result, 43 bioactive compounds of DNt and 69 putative targets were identified. Based on the network analysis, we found seven key bioactive compounds (quercetin, ß-sitosterol, luteolin, kaempferol, supraene, curcumenolactone C, and stigmasterol) of DNt might treat NAFLD via intervening IL6, MAPK8, VEGFA, CASP3, ALB, APP, MYC, PPARG, and RELA. The functional enrichment analysis revealed that DNt might affect NAFLD by modulating the signaling pathways involved in lipid metabolism, inflammation, oxidation, insulin resistance (IR), atherosclerosis, and apoptosis. Furthermore, most key bioactive compounds might bind firmly with the key targets. This study predicted the multicomponent, multitarget, and multipathway mechanisms of DNt in the treatment of NAFLD from a holistic perspective. DNt could be a promising agent for NAFLD, but further experimental verifications are still needed.

Evaluation of inhibitors of intestinal UDP-glucuronosyltransferases 1A8 and 1A10 using raloxifene as a substrate in Caco-2 cells: Studies with four flavonoids of Scutellaria baicalensis

UDP glucuronosyltransferases (UGTs) of the gastrointestinal tract play a crucial role in protection against the toxic effects of xenobiotics in the environment. UGTs such as UGT1A8 and UGT1A10 are predominantly expressed in gastrointestinal tissues. In this study, we examined the phase II metabolism of raloxifene in differentiated Caco-2 monolayers by inducing UGT1A8 and UGT1A10 expression in these cells. The present study evaluated the following four flavonoids of Scutellaria baicalensis as model herbal compounds: scutellarein, salvigenin, baicalein, and wogonin. All test compounds, endpoint substrates, and their metabolites were quantified using liquid chromatography and high-resolution mass spectrometry. The transepithelial electrical resistance values for the individual compounds were comparable regardless of whether they were measured individually. Salvigenin significantly inhibited UGT1A8 and UGT1A10 activities in a concentration-dependent manner. All individual compounds except scutellarein inhibited UGT1A8 and UGT1A10 activity at a concentration of 100 μM. In addition, all individual flavonoids at 100 μM, except wogonin, significantly increased the amount of raloxifene in the basolateral chambers. The positive control, canagliflozin, significantly inhibited both UGT1A8 and UGT1A10 activities. These findings suggest that the Caco-2 assay can be utilized for identifying UGT1A8 and UGT1A10 inhibitors and indicate the potential of salvigenin for enhancing the pharmacological effects of UGT substrate drugs.

Use of Herbal Medicine by Pregnant Women: What Physicians Need to Know

About 80% of the consumers worldwide use herbal medicine (HMs) or other natural products. The percentage may vary significantly (7%-55%) among pregnant women, depending upon social status, ethnicity, and cultural traditions. This manuscript discusses the most common HMs used by pregnant women, and the potential interactions of HMs with conventional drugs in some medical conditions that occur during pregnancy (e.g., hypertension, asthma, epilepsy). It also includes an examination of the characteristics of pregnant HM consumers, the primary conditions for which HMs are taken, and a discussion related to the potential toxicity of HMs taken during pregnancy. Many cultures have used HMs in pregnancy to improve wellbeing of the mother and/or baby, or to help decrease nausea and vomiting, treat infection, ease gastrointestinal problems, prepare for labor, induce labor, or ease labor pains. One of the reasons why pregnant women use HMs is an assumption that HMs are safer than conventional medicine. However, for pregnant women with pre-existing conditions like epilepsy and asthma, supplementation of conventional treatment with HMs may further complicate their care. The use of HMs is frequently not reported to healthcare professionals. Providers are often not questioning HM use, despite little being known about the HM safety and HM-drug interactions during pregnancy. This lack of knowledge on potential toxicity and the ability to interact with conventional treatments may impact both mother and fetus. There is a need for education of women and their healthcare professionals to move away from the idea of HMs not being harmful. Healthcare professionals need to question women on whether they use any HMs or natural products during pregnancy, especially when conventional treatment is less efficient and/or adverse events have occurred as herbal-drug interactions could be the reason for these observations. Additionally, more preclinical and clinical studies are needed to evaluate HM efficacy and toxicity.

Acid diterpenes from Copaiba oleoresin (Copaifera langsdorffii): Chemical and plasma stability and intestinal permeability using Caco-2 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Copaiba oleoresin has been used in folk medicine in the treatment of bronchitis, syphilis, skin diseases and ulcers due to its anti-inflammatory and antiseptic activities, but there is no information about major compounds oral absorption to support the traditional use.

AIM OF STUDY

Considering the potential of copalic (CA) and kaurenoic acid (KA) - major biological activity (in vitro) diterpenes found in the oleoresin, this study aimed to evaluate the intestinal permeability of CA and KA using Caco-2 cells model as predictive test for oral drug absorption.

MATERIALS AND METHODS

Chemical stability at pH 1.2 and 7.4 and plasma stability were evaluated to mimic physiological conditions of the gastrointestinal tract. The intestinal permeability of CA and KA was evaluated in Caco-2 cells in the presence and absence of the P-glycoprotein inhibitor verapamil.

RESULTS

CA and KA were rapidly degraded at pH 1.2 (0.2 M Clark-Lubs buffer). At pH 7.4 (0.1 M phosphate buffer), CA was stable for up to 24 h and KA for up to 6 h. In human plasma, CA and KA can be considered stable for 24 h and 12 h at 37 °C, respectively. Caco-2 cells were considered viable when incubated with CA or KA in the range of 3.9-250 μM for 24 h. CA and KA exhibited moderate apparent permeability (P_app) of 4.67 (±0.08) × 10^-6 cm/s and 4.66 (±0.04) × 10^-6 cm/s, respectively. Simultaneous incubation with verapamil showed that P-glycoprotein does not play a relevant role on CA and KA oral absorption, with P_app of 4.48 (±0.26) × 10^-6 cm/s and 5.37 (±0.72) × 10^-6 cm/s observed for CA and KA, respectively.

CONCLUSION

The oral absorption of both CA and KA is driven by mainly passive permeability, is not limited by p-glycoprotein, but enteric-coated dosage forms should be used to avoid chemical instability in the gastric pH.

Overview and Comparison of Intestinal Organotypic Models, Intestinal Cells, and Intestinal Explants Used for Toxicity Studies

The intestine is a complex organ formed of different types of cell distributed in different layers of tissue. To minimize animal experiments, for decades, researchers have been trying to develop in vitro/ex vivo systems able to mimic the cellular diversity naturally found in the gut. Such models not only help our understanding of the gut physiology but also of intestinal toxicity. This review describes the different systems used to evaluate the effects of drugs/contaminants on intestinal functions and compares their advantages and limitations. The comparison showed that the organotypic model is the best available model to perform intestinal toxicity studies, including on human tissues.