The systematic separation strategy has long and widely been applied in the research and development of herbal medicines. However, the pharmacological effects of many bioactive constituents are much weaker than those of the corresponding herbal extracts. Thus, there is a consensus that purer herbal extracts are sometimes less effective. Pharmacological loss of purified constituents is closely associated with their significantly reduced intestinal absorption after oral administration. In this review, pharmacokinetic synergies among constituents in herbal extracts during intestinal absorption were systematically summarized to broaden the general understanding of the pharmaceutical nature of herbal medicines. Briefly, some coexisting constituents including plant-produced primary and secondary metabolites, promote the intestinal absorption of active constituents by improving solubility, inhibiting first-pass elimination mediated by drug-metabolizing enzymes or drug transporters, increasing the membrane permeability of enterocytes, and reversibly opening the paracellular tight junction between enterocytes. Moreover, some coexisting constituents change the forms of bioactive constituents via mechanisms including the formation of natural nanoparticles. This review will focus on explaining this new synergistic mechanism. Thus, herbal extracts can be considered mixtures of bioactive compounds and pharmacokinetic synergists. This review may provide ideas and strategies for further research and development of herbal medicines.

Pharmacokinetic studies are crucial for elucidating the effective constituents and formula compatibility of traditional Chinese medicines (TCMs). However, studies have usually been limited to single dosages and detection of systemic blood concentrations. To obtain comprehensive pharmacokinetic information, here we propose a multi-dosage and multi-sampling (blood from portal vein or systemic circulation, and liver) strategy to comparatively study the pharmacokinetics of multi-form TCMs, i.e., pure constituents, TCMs, or TCM formula extracts. Based on this strategy, we studied the pharmacokinetics of pure berberine, berberine in Coptidis Rhizoma (CRE), and berberine in Coptidis Rhizoma-Glycyrrhizae Radix et Rhizoma extracts (CR-GRE). After simple calculation and comparison of the obtained area under the curve (AUC) values, the results revealed the drastically different pharmacokinetic properties of pure berberine compared to CRE and CR-GRE. The results contribute to explaining the pharmacological loss of berberine activity after purification and the compatibility of the CR-GR drug pair. The results also innovatively showed that it was intestinal absorption that differentiated the pharmacokinetics of CRE and pure berberine, and CRE and CR-GRE. In conclusion, we propose a composite strategy to comparatively study the pharmacokinetics of TCMs, which could provide sufficient information to obtain a comprehensive view, before follow-up mechanism-of-action studies.

Purpose: Docetaxel (DTX) is a valuable anti-tumor chemotherapy drug with limited oral bioavailability. This study aims to develop an effective oral delivery system for DTX using natural nanoparticles (Nnps) derived from Coptidis Rhizoma extract. Methods: DTX-loaded self-assembled nanoparticles (Nnps-DTX) were created using an optimized heat-induction strategy. Nnps-DTX’s shape, size, Zeta potential, and in vitro stability were all carefully examined. Additionally, the study investigated the encapsulation efficiency, loading capacity, crystal form, and intermolecular interactions of DTX in Nnps-DTX. Subsequently, the solubility, release, cellular uptake, metabolic stability, and preclinical pharmacokinetics of DTX in Nnps-DTX were systematically evaluated. Finally, the cytotoxicity of Nnps-DTX was assessed in three tumor cell lines. Results: Nnps-DTX was spherical in shape, 138.6 ± 8.2 nm in size, with a Zeta potential of − 20.8 ± 0.6 mV, a DTX encapsulation efficiency of 77.6 ± 8.5%, and a DTX loading capacity of 6.8 ± 1.9%. Hydrogen bonds, hydrophobic interactions, and electrostatic interactions were involved in the formation of Nnps-DTX. DTX within Nnps-DTX was in an amorphous form, resulting in enhanced solubility (23.3 times) and release compared to free DTX. Following oral treatment, the mice in the Nnps-DTX group had DTX peak concentrations 8.8, 23.4, 44.6, and 5.7 times higher in their portal vein, systemic circulation, liver, and lungs than the mice in the DTX group. Experiments performed in Caco-2 cells demonstrated a significant increase in DTX uptake by Nnps-DTX compared to free DTX, which was significantly inhibited by indomethacin, an inhibitor of caveolae-mediated endocytosis. Furthermore, compared to DTX, DTX in Nnps-DTX demonstrated better metabolic stability in liver microsomes. Notably, Nnps-DTX significantly reduced the viability of MCF-7, HCT116, and HepG2 cells. Conclusion: The novel self-assembled nanoparticles considerably enhanced the cellular absorption, solubility, release, metabolic stability, and pharmacokinetics of oral DTX and demonstrated strong cytotoxicity against tumor cell lines.

Background/Objectives: Natural macromolecule-based drug delivery carriers have gained extensive attention for biomedical applications. This study aimed to construct an efficient oral delivery system for the widely used antitumor drug docetaxel (DTX) by utilizing natural nanoparticles derived from Ganoderma (LZ-Nnps). Methods: LZ-Nnps loaded with DTX (LZ-Nnps-DTX) were fabricated via an optimized heat-induced self-assembly approach and characterized for morphology, particle size, zeta potential, stability, drug loading, encapsulation efficiency, and molecular interactions with DTX. Intestinal absorption, pharmacokinetics, and tissue distribution were respectively assessed, while antitumor efficacy, macrophage internalization mechanisms, and immunomodulatory activation were further investigated. Results: The optimized formulation showed a particle size of 361.3 ± 5.3 nm, zeta potential of −39.55 ± 1.31 mV, drug loading of 1.51 ± 0.08%, and near-complete encapsulation efficiency (99.97 ± 0.02%), with favorable stability in gastrointestinal fluids. Hydrogen bonding and hydrophobic interactions effectively kept DTX in a stable amorphous state. LZ-Nnps-DTX markedly improved DTX aqueous solubility, dissolution, and intestinal absorption. In vivo assays showed oral LZ-Nnps-DTX achieved 34-fold higher C_max and 7.8-fold larger plasma AUC_0-t than free DTX, and mainly accumulated in the liver and lung. The nanoparticles entered Caco-2 cells via macropinocytosis and mainly accumulated in the liver. LZ-Nnps-DTX exerted strong cytotoxicity against HepG2, A549, and HCT116 cells, was internalized by RAW264.7 macrophages through caveolae-mediated endocytosis and phagocytosis, and stimulated TNF-α and NO production to suppress tumor growth. Conclusions: These findings demonstrate that LZ-Nnps-DTX effectively enhances oral bioavailability, exerts potent antitumor effects, and activates macrophage-mediated immunity, supporting its promise as an oral DTX delivery system.