Abu Hasanat Md. Zulfiker

Objective: Current antiplatelet medications increase the risk of bleeding, which leads to a clear clinical need in developing novel mechanism-based antiplatelet drugs. TYMP (Thymidine phosphorylase), a cytoplasm protein that is highly expressed in platelets, facilitates multiple agonist-induced platelet activation, and enhances thrombosis. Tipiracil hydrochloride (TPI), a selective TYMP inhibitor, has been approved by the Food and Drug Administration for clinical use. We tested the hypothesis that TPI is a safe antithrombotic medication. Approach and Results: By coexpression of TYMP and Lyn, GST (glutathione S-transferase) tagged Lyn-SH3 domain or Lyn-SH2 domain, we showed the direct evidence that TYMP binds to Lyn through both SH3 and SH2 domains, and TPI diminished the binding. TYMP deficiency significantly inhibits thrombosis in vivo in both sexes. Pretreatment of platelets with TPI rapidly inhibited collagen- and ADP-induced platelet aggregation. Under either normal or hyperlipidemic conditions, treating wild-type mice with TPI via intraperitoneal injection, intravenous injection, or gavage feeding dramatically inhibited thrombosis without inducing significant bleeding. Even at high doses, TPI has a lower bleeding side effect compared with aspirin and clopidogrel. Intravenous delivery of TPI alone or combined with tissue plasminogen activator dramatically inhibited thrombosis. Dual administration of a very low dose of aspirin and TPI, which had no antithrombotic effects when used alone, significantly inhibited thrombosis without disturbing hemostasis. Conclusions: This study demonstrated that inhibition of TYMP, a cytoplasmic protein, attenuated multiple signaling pathways that mediate platelet activation, aggregation, and thrombosis. TPI can be used as a novel antithrombotic medication without the increase in risk of bleeding.

Toxins from toads have long been known to contain rich chemicals with great pharmaceutical potential. Recent studies have shown more than 100 such chemical components, including peptides, steroids, indole alkaloids, bufogargarizanines, organic acids, and others, in the parotoid and skins gland secretions from different species of toads. In traditional Chinese medicine (TCM), processed toad toxins have been used for treating various diseases for hundreds of years. Modern studies, including both experimental and clinical trials, have also revealed the molecular mechanisms that support the development of these components into medicines for the treatment of inflammatory diseases and cancers. More recently, there have been studies that demonstrated the therapeutic potential of toxins from other species of toads, such as Australian cane toads. Previous reviews mostly focused on the pharmaceutical effects of the whole extracts from parotoid glands or skins of toads. However, to fully understand the molecular basis of toad toxins in their use for therapy, a comprehensive understanding of the individual compound contained in toad toxins is necessary; thus, this paper seeks to review the recent studies of some typical compounds frequently identified in toad secretions.

Glycolipids from Mycobacterium tuberculosis have a profound impact on the innate immune response of the host. Macrophage‐inducible C‐type lectin (Mincle) is a pattern‐recognition receptor that has been shown to bind trehalose dimycolate (TDM) from the mycobacterium and instigate intracellular signalling in the immune cell. There are structural similarities between the structures of TDM and phosphatidyl inositol mannoside (PIM). We thus hypothesized that these latter structures might also modulate an immune response in a similar manner. To test this, we synthesized a series of new mannose derivatives modified with fatty esters at the 6‐position and assessed the release of inflammatory cytokines in human U937 macrophages under the induction of lipopolysaccharides (LPS) after glycolipid treatment. The results showed that the amount of two major cytokines—tumour necrosis factor (TNF)‐α and interleukin (IL)‐6—released from LPS‐stimulated U937 cells decreased significantly when compared to a control upon treatment with the prepared glycolipids, thus indicating a reduction in cytokine production by the macrophages.

Recent evidences show that activation of serotonin 2A receptors (5-HT_2AR) by agonists is significant in improving therapeutic activity of disease conditions, such as obsessive-compulsive disorder (OCD). Though the exact molecular mechanism is still not well understood, it is thought to involve agonist-driven, enhanced expression of 5-HT_2AR in certain areas of brain, such as the pre-frontal cortex (PFC). Several other reports have also demonstrated association of OCD with lower dopamine receptor (D₂R) availability, primarily in the striatum of the brain along with dysfunction of 5-HT_2AR-D₂R heteromer regulation. We thus hypothesized that compound(s) interacting with this molecular mechanism could be developed as drugs for long-term beneficial effects against OCD. In the present study, we have obtained experimental evidence in cultured neuronal cells (CLU213) that aqueous extract (AE, 50 μg/mL, P < 0.05) of the Australian cane toad skin significantly increased the levels of 5-HT_2AR and D₂R protein and mRNA expression. AE was also found to enhance the interaction between 5-HT_2AR and D₂R and formation of expression of 5-HT_2AR-D₂R heteromer using co-immunoprecipitation and Western blot. Further investigation showed the involvement of classical signaling pathway (G_q/11-PLCβ) along with c-FOS transcription factor preferentially in 5-HT_2A-mediated agonist activation. These results obtained demonstrated that AE upregulates 5-HT_2AR by a mechanism that appears to involve G_q/11-PLCβ signaling pathway and c-FOS transcription factor activation. We indicate this enhanced 5-HT_2AR and D₂R expression and their interaction to induce increased 5-HT_2AR-D₂R heteromer formation by exposure to AE might provide a molecular mechanism to develop potential novel drug candidates to ameliorate OCD symptoms. J. Cell. Biochem. 9999: 1–15, 2016.

Indolealkylamines (IAAs) are biogenic amines and derivatives of 5-hydroxytryptamine, acting primarily on serotonin receptors. IAAs are often considered the most thoroughly investigated group of aromatic amines in the amphibian skin. On the contrary, at present the detailed knowledge of these compounds in lower organisms is still limited and the biogenic amine receptors, mediating hormonal and modulatory functions, are largely unknown in primitive invertebrates. However, some active research is currently underway investigating this class of biogenic amines. Notably, during the last three decades several investigations have demonstrated the biological activity of endogenous biogenic amines in cnidarians, which are known to be the lowest beings equipped with an effective, even though rudimentary, nervous system. Toads, especially those from the Bufonidae family, constitute a significant part of the amphibian family and are an identified source of IAAs. To date fourteen IAAs have been identified in the skins of toad species. All are 5-substituted IAA derivatives acting mainly on the central nervous system (CNS), with most exhibiting some degrees of 5-HT_2A receptor selectivity. This selective ability presents potential for their use in the development of treatments for various disorders such as schizophrenia, depression, anxiety, obsessive-compulsive disorders and chronic pain conditions. There are indications that some IAAs may also show subclass selectivity through binding to multiple 5-HT receptor subtypes. Thus, there exists an additional promising platform for the development of therapeutics targeting multiple 5-HT receptors. In this review, IAAs occurring naturally in various species of toad skins, which have been identified and isolated since 1944 are summarized and comparisons are made with similar biogenic amines recognized in cnidarians to date. Such comparisons highlight the potential to utilize existing knowledge gathered from vertebrates, such as toads in order to improve the understanding of the activities of such compounds in lower invertebrates.

Purpose: To pharmacologically investigate the methanol and petroleum ether extracts of the plant leaves of Manilkara zapota (MZME and MZPE, respectively), Abroma augusta (AAME and AAPE, respectively) and Vitex negundo (VNME and VNPE, respectively). Methods: Analgesic and anti-diarrheal activities were assessed by acetic acid-induced writhing and castor oil-induced diarrhea in mice, respectively, while CNS depressant activity was evaluated using hole-cross and open-field method by observing the decrease in exploratory behavior and spontaneous motor activity in mice, respectively. Results: All the extracts exhibited good analgesic activity at a dose of 200 mg/kg with the following rank order of activity: MZME > MZPE > VNME > VNPE > AAME > AAPE. Analgesic activity was insignificant at 100 mg/kg dose except for VNPE (67.81 % inhibition). The extracts produced significant reduction in diarrheal episodes in mice at a dose of 400 mg/kg MZPE (highest protection: 80.3 %, p < 0.05) and VNME (lowest protection: 38.6 %, p < 0.001). The extracts demonstrated CNS depressant activity in a dose-dependent manner (p < 0.05 compared to the standard except for AAME and AAPE which showed insignificant activity). Conclusion: The results indicate that the traditional use of the investigated plants appears to be justified; however, further studies are required to unravel the underlying mechanisms of action.Griffith Health, School of Medical ScienceFull Tex

Toad glandular secretions and skin extractions contain many natural agents which may provide a unique resource for novel drug development. The dried secretion from the auricular and skin glands of Chinese toad (Bufo bufo gargarizans) is named Chansu, which has been used in Traditional Chinese Medicine (TCM) for treating infection and inflammation for hundreds of years. The sterilized hot water extraction of dried toad skin is named Huachansu (Cinobufacini) which was developed for treating hepatitis B virus (HBV) and several types of cancers. However, the mechanisms of action of Chansu, Huachansu, and their constituents within are not well reported. Existing studies have suggested that their anti‐inflammation and anticancer potential were via targeting Nuclear Factor (NF)‐κB and its signalling pathways which are crucial hallmarks of inflammation and cancer in various experimental models. Here, we review some current studies of Chansu, Huachansu, and their compounds in terms of their use as both anti‐inflammatory and anticancer agents. We also explored the potential use of toad glandular secretions and skin extractions as alternate resources for treating human cancers in combinational therapies.