Synthesis, in silico and in vivo blood brain barrier permeability of ginkgolide B cinnamate

Enhanced Brain Targeting Delivery of Salvianic Acid Using Borneol as a Promoter of Blood/Brain Transport and Regulator of P-gp

BACKGROUND

Borneol can enhance the blood-brain barrier (BBB) permeability of some drugs and suppress the efflux transport of P-glycoprotein (P-gp), which will contribute to the brain delivery of salvianic acid A (SAA).

OBJECTIVE

The study aimed to develop an approach to improve the brain targeting delivery of SAA with the aid of borneol.

MATERIALS AND METHODS

"Borneol" was involved in SAA via esterified prodrug SAA borneol ester (SBE) and combined administration (SAA-borneol, SAA-B). Subsequently, the blood-brain transport of SAA through brain/blood distribution and P-gp regulation via expression and function assay were investigated in rats.

RESULTS

The SBE and SAA-B-treated group received a three-fold brain concentration and longer t1/2 and retention period of active SAA than that of SAA alone (20.18/13.82 min vs. 6.48 min; 18.30/17.42 min vs. 11.46 min). In addition, blood to brain transport of active SAA in SBE was altered in comparison to that of SAA-B, ultimately resulting in a better drug targeting index (9.93 vs. 3.63). Further studies revealed that SBE-induced downregulation of P-gp expression occurred at the later stage of administration (60 min, P < 0.01), but SBE always showed a more powerful drug transport activity across BBB represented by Kp value of rhodamine 123 than SAA-B (30, 60 min, P < 0.05).

CONCLUSION

The comparative results indicate that SBE exhibits prominent efficiency on SAA's targeting delivery through improved blood/brain metabolic properties and sustained inhibitory effect of "borneol" on P-gp efflux. Therefore, prodrug modification can be applied as a more effective approach for brain delivery of SAA.

Structure, synthesis, biosynthesis, and activity of the characteristic compounds from Ginkgo biloba L

Covering: 1928-2021Ginkgo biloba L. is one of the most distinctive plants to have emerged on earth and has no close living relatives. Owing to its phylogenetic divergence from other plants, G. biloba contains many compounds with unique structures that have served to broaden the chemical diversity of herbal medicine. Examples of such compounds include terpene trilactones (ginkgolides), acylated flavonol glycosides (ginkgoghrelins), biflavones (ginkgetin), ginkgotides and ginkgolic acids. The extract of G. biloba leaf is used to prevent and/or treat cardiovascular diseases, while many ginkgo-derived compounds are currently at various stages of preclinical and clinical trials worldwide. The global annual sales of G. biloba products are estimated to total US$10 billion. However, the content and purity of the active compounds isolated by traditional methods are usually low and subject to varying environmental factors, making it difficult to meet the huge demand of the international market. This highlights the need to develop new strategies for the preparation of these characteristic compounds from G. biloba. In this review, we provide a detailed description of the structures and bioactivities of these compounds and summarize the recent research on the development of strategies for the synthesis, biosynthesis, and biotechnological production of the characteristic terpenoids, flavonoids, and alkylphenols/alkylphenolic acids of G. biloba. Our aim is to provide an important point of reference for all scientists who research ginkgo-related compounds for medicinal or other purposes.

Amide Derivatives of Ginkgolide B and Their Inhibitory Effects on PAF-Induced Platelet Aggregation

Ginkgolides are the most important components of Ginkgo biloba extracts, whose lactone can be hydrolyzed in the aqueous environment. Although the hydrolyzed products have complex structures and their functions are not well-understood, opening the lactone ring is an important strategy in producing novel derivatives of ginkgolide. The preparation of a single pure aminolyzed ginkgolide for the study of its bioactivity and understanding of the process of aminolysis are challenging. To obtain stable aminolyzed products, four amide derivatives (2-5) of ginkgolide B (GB, 1) were prepared via the ring-opening reaction of its lactone with propylamine. These products were purified and fully identified by high-resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR) spectroscopy and were further evaluated for their ability to inhibit the PAF-induced platelet aggregation of rabbit platelets in vitro. Compound 2, which was obtained by selective aminolysis of the lactone ring C of GB, showed a much better inhibitory activity of platelet aggregation (IC₅₀, 15 nM) than the parent compound GB (IC₅₀, 442 nM). The other three products (3-5), which were obtained by the aminolysis of lactone rings C and F of GB, did not show platelet aggregation inhibitory activity. The results greatly extended our understanding of the chemistry of GB and provided important structural information for the exploration and development of new drugs based on ginkgolides in G. biloba.

Nanocarriers for effective nutraceutical delivery to the brain

Neurodegenerative disorders are common among aging populations around the globe. Most are characterized by loss of neurons, protein aggregates, oxidative stress, mitochondrial damage, neuroinflammation among others. Although symptomatic treatment using conventional pharmacotherapy has been widely employed, their therapeutic success is limited due to varied reasons. In the need to identify an alternative approach, researchers successfully demonstrated the therapeutic utility of plant-derived nutraceuticals in cell and animal models of neurodegenerative conditions. However, most nutraceuticals failed during clinical trials in humans owing to their poor bioavailability in vivo and limited permeability across the blood brain barrier (BBB). The current emphasis is therefore on the improved delivery of nutraceuticals to the brain. In this regard, development of nanoparticle conjugated nutraceuticals to enhance bioavailability and therapeutic efficacy in the brain has gained attention. Here, we review the research advances in nanoparticles conjugated nutraceuticals applied in neurodegenerative disorders and discuss their advantages and limitations, clinical trials and toxicity concerns.

Chloride intracellular channel 4 participate in the protective effect of Ginkgolide B in MPP+ injured MN9D cells: insight from proteomic analysis

Background

Ginkgolide B (GB), the extract of G. biloba leaves, has been shown to be protective against many neurological disorders, including Parkinson’s disease (PD). Efforts have been made to synthesized ginkgolides analogs and derivatives with more targeted and smaller molecular weight. In the present study, four GB derivatives (GBHC-1-GBHC-4) were synthesized, and their protective roles in N-methyl-4-phenylpyridinium (MPP +) injured MN9D dopaminergic neuronal cell line were evaluated. Also, cell response mechanisms upon these GB derivatives treatment were analyzed by iTRAQ proteomics.

Methods

MN9D cells were treated with MPP + to induce in vitro cell models of PD. Four GB derivatives (GBHC-1-GBHC-4) were synthesized, and their protective roles on cell viability and apoptosis in in vitro PD model cells were evaluated by CCK8 assay, fluorescence-activated cell sorting and DAPI staining, respectively. The proteomic profiles of MPP+ injured MN9D cells pretreated with or without GB and GB derivatives were detected using the isobaric tags for relative and absolute quantification (iTRAQ) labeling technique.

Results

Pretreatment with GBHC-1-GBHC-4 noticeably increased cell viability and attenuated cell apoptosis in MPP+ -injured MN9D cells. Using proteomic analysis, we identified differentially expressed proteins upon GB and GB derivatives treatment. Chloride intracellular channel 4 (CLIC4) and “protein processing in endoplasmic reticulum” pathways participated in the protective roles of GB and GBHC-4. GB and GBHC-4 pretreatment could significantly reverse MPP+ -induced CLIC4 expression and translocation from cytoplasm to nucleus of MN9D cells.

Conclusions

Quantitative comparative proteomic analysis identified differentially expressed proteins associated with GB and GB derivatives. We further verified the expression of CLIC4 by western blotting and immunocytochemistry assay. This bio-information on the identified pathways and differentially expressed proteins such as CLIC4 provide more targeted directions for the synthesis of more effective and targeted GB derivatives for the treatment of neurological disorders.

The neuroprotective mechanisms of ginkgolides and bilobalide in cerebral ischemic injury: a literature review

The incidence and mortality of strokes have increased over the past three decades in China. Ischemic strokes can cause a sequence of detrimental events in patients, including increased permeability and dysfunction of the blood-brain barrier, brain edema, metabolic disturbance, endoplasmic reticulum stress, autophagy, oxidative stress, inflammation, neuron death and apoptosis, and cognitive impairment. Thrombolysis using recombinant tissue plasminogen activator (rtPA) and mechanical embolectomy with a retrievable stent are two recognized strategies to achieve reperfusion after a stroke. Nevertheless, rtPA has a narrow therapeutic timeframe, and mechanical embolectomy has limited rates of good neurological outcomes. EGb761 is a standardized and extensively studied extract of Ginkgo biloba leaves. The ginkgolides and bilobalide that constitute a critical part of EGb761 have demonstrated protective properties towards cerebral injury. Ginkgolides include Ginkgolide A (GA), Ginkgolide B (GB), Ginkgolide C (GC), Ginkgolide J (GJ), Ginkgolide K (GK), Ginkgolide L (GL), and Ginkgolide M (GM). This review seeks to elucidate the neuroprotective effects and mechanisms of ginkgolides, especially GA and GB, and bilobalide in cerebral injury following ischemic strokes.

Role of Toll-like receptor mediated signaling in traumatic brain injury

The mechanisms underlying secondary brain damage following traumatic brain injury (TBI) remain unclear. A great many studies have demonstrated that inflammatory cascades contribute to brain damage through the activation of immune/inflammatory responses, including the increased release of cytokines and chemokines, and the recruitment of leukocytes. The cells and tissues damaged by primary mechanical injury release a number of endogenous factors acting as damage-associated molecular patterns (DAMPs), which initiate and perpetuate noninfectious inflammatory responses through transduction signaling pathways. Toll-like receptors (TLRs) are a transmembrane receptor family that can recognize the specific DAMPs released from damaged cells and recruit a set of adaptors leading to the activation of downstream kinases and nuclear factors which regulate the expression of inflammatory genes. The activation of inflammatory responses mediated by TLR signaling is closely associated with brain tissue damage and neurological dysfunction following TBI. TLRs and their downstream protein kinases may be potential targets for the treatment of TBI. Modulation of TLR-mediated signaling may attenuate brain damage and improve TBI outcome. In this review, we briefly discuss the role of TLR-mediated signaling in TBI and the new treatments targeting TLR signaling. This article is part of the Special Issue entitled "Novel Treatments for Traumatic Brain Injury".

Enhancement of brain-targeting delivery of danshensu in rat through conjugation with pyrazine moiety to form danshensu-pyrazine ester

Tetramethylpyrazine was introduced to the structure of danshensu (DSS) as P-glycoprotein (P-gp)-inhibiting carrier, designing some novel brain-targeting DSS-pyrazine derivatives via prodrug delivery strategy. Following the virtual screening, three DSS-pyrazine esters (DT1, DT2, DT3) were selected because of their better prediction parameters related to brain-targeting. Among them, DT3 was thought to be a promising candidate due to its appropriate bioreversible property in vitro release assay. Further investigation with regard to DT3's brain-targeting effects in vivo was also reported in this study. High-performance liquid chromatography-diode array detection (HPLC-DAD) method was established for the quantitative determination of DT3 and DSS in rat plasma, brain homogenate after intravenous injection. In vivo metabolism of DT3 indicated that it was first converted into DT1, DT2, then the generation of DSS, which could be the result of carboxylesterase activity in rat blood and brain tissue. Moreover, the brain pharmacokinetics of DT3 was significantly altered with 2.16 times increase in half-life compared with that of DSS, and its drug targeting index (DTI) was up to 16.95. Above these data demonstrated that DT3 had better tendency of brain-targeting delivery, which would be positive for the treatment of brain-related disorders.

Novel ginkgolide B derivative attenuated the function and expression of P-glycoprotein at the blood–brain barrier, presenting brain-targeting ability

The effects of ginkgolide B derivative (GBD) and GB on P-glycoprotein efflux function and expression level were studied to explain GBD's brain-targeting behavior.