UHPLC-MS method for determination of gambogic acid and application to bioavailability, pharmacokinetics, excretion and tissue distribution in rats

Caged Polyprenylated Xanthones in Garcinia hanburyi and the Biological Activities of Them

The previous phytochemical analyses of Garcinia hanburyi revealed that the main structural characteristic associated with its biological activity is the caged polyprenylated xanthones with a unique 4-oxatricyclo [4.3.1.03,7] dec-2-one scaffold, which contains a highly substituted tetrahydrofuran ring with three quaternary carbons. Based on the progress in research of the chemical constituents, pharmacological effects and modification methods of the caged polyprenylated xanthones, this paper presents a preliminary predictive analysis of their drug-like properties based on the absorption, distribution, metabolism, excretion and toxicity (ADME/T) properties. It was found out that these compounds have very similar pharmacokinetic properties because they possess the same caged xanthone structure, the 9,10-double bond in a,b-unsaturated ketones are critical for the antitumor activity. The author believes that there is an urgent need to seek new breakthroughs in the study of these caged polyprenylated xanthones. Thus, the research on the route of administration, therapeutic effect, structural modification and development of such active ingredients is of great interest. It is hoped that this paper will provide ideas for researchers to develop and utilize the active ingredients derived from natural products.

Lactoferrin-Modified Gambogic Acid Liposomes for Colorectal Cancer Treatment

Colorectal cancer (CRC) therapy is a big challenge, and seeking an effective and safe drug is a pressing clinical need. Gambogic acid is a potent antineoplastic agent without the drawback of bone marrow suppression. To improve its druggability (e.g., poor water solubility and tumor delivery), a lactoferrin-modified gambogic acid liposomal delivery system (LF-lipo) was developed to enhance the treatment efficacy of CRC. The LF-lipo can specifically bind LRP-1 expressed on colorectal cancer cells to enhance drug delivery to the tumor cells and yield enhanced therapeutic efficacy. The LF-lipo promoted tumor cell apoptosis and autophagy, reduced reactive oxygen species (ROS) levels in tumor cells, and inhibited angiogenesis; moreover, it could also repolarize tumor-associated macrophages from the M2 to M1 phenotype and induce ICD to activate T cells, exhibiting the capability of remodeling the tumor immune microenvironment. The liposomal formulation yielded an efficient and safe treatment outcome and has potential for clinical translation.

Optimization of amino acid-based poly(ester urea urethane) nanoparticles for the systemic delivery of gambogic acid for treating triple negative breast cancer

Amino acid-based poly(ester urea urethane) (AA-PEUU) is developed from amino acid-based ester urea building blocks interconnected with urethane blocks functionalized with poly(ethylene glycol) (PEG). Each functional block consists of structural design features that could impact the properties and performances of AA-PEUU as a nanocarrier for the systemic delivery of gambogic acid (GA). The multifunctional AA-PEUU structure provides broad tunability to enable the optimization of nanocarriers. The study investigates the structure-property relationship by fine-tuning the structure of AA-PEUU, including the amino acid type, hydrocarbons, the ratio of functional building blocks, and PEGylation, to identify the nanoparticle candidate with optimized delivery performances. Compared to free GA, the optimized PEUU nanocarrier improves the intratumoral distribution of GA by more than 9-fold, which significantly enhances the bioavailability and persistence of GA after intravenous administration. In an MDA-MB-231 xenograft mouse model, GA delivered by the optimized AA-PEUU nanocarrier exhibits significant tumor inhibition, apoptosis induction, and the anti-angiogenesis effect. The study demonstrates the potency of engineering AA-PEUU nanocarriers with tailor-designed structures and versatile tunability for the systemic delivery of therapeutics in the treatment of triple negative breast tumor.

PDT-sensitized ROS-responsive dextran nanosystem for maximizing antitumor potency of multi-target drugs

The heterogeneity of tumor microenvironment leads to uneven distribution of bio-stimuli. Thus, the multi-site delivery efficiency of responsive drug delivery systems (DDS) inner tumor was always limited. Herein, we proposed a combination strategy of photodynamic therapy (PDT) with ROS-responsive nanosystem which was constructed from dextran-phenylboronic acid pinacol ester conjugates. This combination utilized PDT to amplify and homogenize tissular oxidation level, and achieve effective multi-site response and release of multi-target drugs like gambogic acid (GA). Our research demonstrated the successful preparation of GA and protoporphyrin IX (PpIX) co-loaded nanoparticles, and the PDT-mediated spatiotemporal controlled multi-site drug release in simulated conditions. Furthermore, data from in vitro and in vivo researches on B16F10 cells, HUVEC, and B16F10-bearing C57BL/6 mice potently confirmed the enhanced multi-mechanism regulations of GA mediated by the effective and homogeneous tumoral release. This tactic based on bio-stimuli amplification and homogenization proposes a paradigm to maximize the potency of multi-target drugs.

Determination and tissue distribution comparisons of five xanthones after orally administering crude and processed gamboge

Caged polyprenylated xanthones are the main active ingredients isolated from the resin of Garcinia hanburyi, which has been reported to exhibit potential anticancer and anti-inflammatory activities. This study aimed to develop sensitive and specific ultra-performance liquid chromatography coupled with the triple quadrupole mass spectrometry method for investigating the tissue distribution of five xanthones in rats: β-morellic acid, isogambogenic acid, gambogenic acid, R-gambogic acid and S-gambogic acid. All tissue samples were prepared using the liquid-liquid extraction method and separated on a C₈ column with a gradient system. Detection was performed on a triple quadrupole mass spectrometer in multiple-reaction monitoring using positive ionization. The method established in this assay was successfully applied to the tissue distribution study of the five selected xanthones after orally administering crude and processed gamboge in rat tissues. The results indicated that these five xanthones were distributed to rat tissues rapidly and could be detected in all of the selected tissues after oral administration. After processing, the contents of R-gambogic acid and S-gambogic acid in the gastrointestinal tract were significantly reduced. The findings of this study might be helpful in further understanding the processing mechanism of gamboge and providing references for its reasonable clinical application.

Topical delivery of gambogic acid assisted by the combination of low-frequency ultrasound and chemical enhancers for chemotherapy of cutaneous melanoma

Anti-cutaneous melanoma activity of the skin-delivered gambogic acid (GA) has been reported in our previous study. However, it is difficult for GA to diffuse passively through intact skin without any enhancement means. In this study, a combination of chemical enhancers (EN: azone and propylene glycol) and physical ultrasound (US) was used to improve the percutaneous permeation of GA and enhance the anti-melanoma activity. The enhancement effect of the combination of EN and US (EN-US) on GA in vitro and in vivo was studied, and the enhancement mechanism and skin irritation were also evaluated. We showed that the parameters of US application at a constant frequency (30 kHz) with a duty cycle of 100% and intensity of 1.75 W/cm² for 20 min were optimal. In vitro, EN-US showed a considerable enhancement of the permeation of GA, and the enhancement effect was stronger than that with the use of EN or US alone. In vivo antitumor study showed that the tumor growth was significantly inhibited after percutaneous administration of GA by EN-US, more than in the intravenous injection group. The penetration enhancement mechanism revealed that EN-US not only altered the structure of lipid bilayers and keratins to reduce the barrier effect of the stratum corneum but also produced diffusion channels in the skin under the cavitation effect of US, thereby promoting the skin penetration of GA. In addition, there was no observable skin irritation in mice after treatment with EN-US. Our study demonstrated that the combination of EN and US improved the skin permeation and retention of GA to enhance the anti-melanoma activity. This method also provides technical guidance for the future development of topical and transdermal therapeutic system of GA.

New Delivery Route of Gambogic Acid Via Skin for Topical Targeted Therapy of Cutaneous Melanoma and Reduction of Systemic Toxicity

Cutaneous melanoma is the deadliest form of skin cancer, and gambogic acid (GA) exhibits potent anti-melanoma activity. However, clinical application of GA via intravenous injection and oral administration is limited by systemic toxicity and rapid metabolism in the blood. Here, we developed a new, topical route of GA delivery for anti-melanoma activity and reduction of systemic toxicity. The results indicated that the barrier of the stratum corneum (SC) and low diffusion of GA in the hydrophilic viable skin (epidermis and dermis) limited the GA penetration through intact skin. The combination of azone (AZ) and propylene glycol (PG) showed obvious synergistic effects on skin penetration by GA via improving the permeability of the SC and greatly increasing the skin accumulation of GA, thereby forming a high drug concentration in the skin and achieving a topical targeted treatment of melanoma. In addition, GA (AZ-PG) achieved the same anti-melanoma effect via topical delivery as via intravenous injection. Intravenous injection and oral administration of GA induced remarkable pathological changes in various organs in mice, whereas GA was not toxic to various organs or to the skin via topical delivery. These findings indicated that topical administration of GA is an alternative route for melanoma treatment.

Validated LC-MS/MS method for quantitation of demethylbellidifolin in rat plasma and its application to pharmacokinetic and bioavailability studies

Demethylbellidifolin, a major xanthone compound of Swertia davidi Franch, shows many beneficial pharmacological effects including antioxidation, anti-inflammation, anti-fibrosis and cardiovascular protection effects. In this research, a rapid and sensitive LC-MS/MS method for the quantitative analysis of demethylbellidifolin in rat plasma was developed. The demethylbellidifolin and internal standard of aurantio-obtusin were extracted from 50 μL of rat plasma samples with ethyl acetate, then the dried residue was reconstituted and injected in an HPLC system with Zorbax SB-C₁₈ analytical column (2.1 × 100 mm, 3.5 μm) and eluted with the mobile phase consisting of methanol and 0.2% formic acid aqueous solution (80:20, v/v). Quantification was performed using a TSQ Quantum Ultra mass spectrometer in negative ESI using selected reaction monitoring mode of the transitions m/z 259.1 → 215.1 for demethylbellidifolin and 329.0 → 314.2 for the IS. Excellent linearity was observed between 1.92 and 960 ng/mL with a limit of quantitation of 1.92 ng/mL. Intra- and inter-day precision (RSD) values of quality control samples were both <8.3%. This study was successfully utilized for the pharmacokinetic profiles of demethylbellidifolin in rats after oral or intravenous administration. The oral bioavailability of demethylbellidifolin was 3.6%.

Caged Garcinia Xanthones, a Novel Chemical Scaffold with Potent Antimalarial Activity

Caged Garcinia xanthones (CGXs) constitute a family of natural products that are produced by tropical/subtropical trees of the genus Garcinia CGXs have a unique chemical architecture, defined by the presence of a caged scaffold at the C ring of a xanthone moiety, and exhibit a broad range of biological activities. Here we show that synthetic CGXs exhibit antimalarial activity against Plasmodium falciparum, the causative parasite of human malaria, at the intraerythrocytic stages. Their activity can be substantially improved by attaching a triphenylphosphonium group at the A ring of the caged xanthone. Specifically, CR135 and CR142 were found to be highly effective antimalarial inhibitors, with 50% effective concentrations as low as ∼10 nM. CGXs affect malaria parasites at multiple intraerythrocytic stages, with mature stages (trophozoites and schizonts) being more vulnerable than immature rings. Within hours of CGX treatment, malaria parasites display distinct morphological changes, significant reduction of parasitemia (the percentage of infected red blood cells), and aberrant mitochondrial fragmentation. CGXs do not, however, target the mitochondrial electron transport chain, the target of the drug atovaquone and several preclinical candidates. CGXs are cytotoxic to human HEK293 cells at the low micromolar level, which results in a therapeutic window of around 150-fold for the lead compounds. In summary, we show that CGXs are potent antimalarial compounds with structures distinct from those of previously reported antimalarial inhibitors. Our results highlight the potential to further develop Garcinia natural product derivatives as novel antimalarial agents.