Melittin, a major peptide component of bee venom, and its conjugates in cancer therapy

Na+/K+ ATPase-targeted delivery to metastatic breast cancer models

In this study, we reported doxorubicin (DOX)-encapsulated nanoparticles (NPs) formulated with biocompatible and biodegradable poly (lactic-co-glycolic acid) (PLGA) and modified with a 13-amino acid peptide (S3) against sodium/potassium (Na⁺/K⁺)-ATPase pump alpha subunit to investigate its potential as antitumor agent. The morphological properties and size dispersity of the prepared nanoparticles were evaluated using scanning electron microscope (SEM) and dynamic light scattering (DLS). The encapsulation efficiency and in vitro release during 7 days were evaluated. Comparative in vitro cytotoxicity experiments demonstrated that the S3-conjugated nanoparticles (S3-PLGA-DOX NPs) had higher antiproliferative activity. Flow cytometry analysis confirmed the enhanced cellular uptake of S3-PLGA-DOX NPs in comparison with PLGA-DOX. In vivo study in 4T1 tumor-bearing BALB/C mice revealed that the S3-functionalized DOX-loaded NPs improved antitumor activity and survival rate of 4T1 tumor bearing mice. In this regard, conjugation of S3 peptide to the surface of DOX-loaded PLGA NPs provides site-specific delivery of DOX, inhibits 4T1 tumor growth in vivo and significantly decreases systemic toxicity. The obtained results suggested that the new (Na⁺/K⁺)-ATPase pump-targeted PLGA NPs as a target-selective delivery system for DOX has great potential for the treatment of breast cancer.

Construction of Dually Responsive Nanotransformers with Nanosphere-Nanofiber-Nanosphere Transition for Overcoming the Size Paradox of Anticancer Nanodrugs

Tumor microenvironment (TME)-responsive nanosystems represent a category of intelligent nanomaterials for precise anticancer drug delivery. Herein, we report a smart size-/morphology-switchable nanodrug that can respond to the acidic TME and near-infrared (NIR) laser irradiation for effective tumor ablation and tumor metastasis inhibition. The nanoagent is physically assembled by a cytolytic peptide, melittin (MEL), an NIR-absorbing molecule, cypate, and a tumor-targeting polymer, hyaluronic acid (HA). At pH 7.4, the as-formed MEL/Cypate@HA complexes are negatively charged nanospheres (∼50 nm), which are suitable for long-term systemic circulation. When these nanospheres actively target tumors, the weakly acidic TME triggers an in situ transformation of the nanospheres to net-like nanofibers. Compared with the nanospheres, the nanofibers not only exhibit an inhibitory effect on tumor cell mobility but also significantly prolong the retention time of MEL/Cypate@HA in tumor tissues for MEL-based chemotherapy. Moreover, the nanofibers can be photodegraded into small nanospheres (∼25 nm) by NIR laser irradiation during cypate-mediated photothermal therapy, which enables deep tumor penetration of the loaded MEL and thus achieves effective tumor eradication. This work provides a facile strategy for converting naturally occurring therapeutic peptides into a TME-responsive drug delivery system and may inspire the development of nanomaterials with changeable structures for therapeutic purposes.

The membrane effects of melittin on gastric and colorectal cancer

The cytotoxic effects of melittin, a bee-venom peptide, have been widely studied towards cancer cells. Typically, these studies have examined the effect of melittin over extended-time courses (6-24 hours), meaning that immediate cellular interactions have been overlooked. In this work, we demonstrate the rapid effects of melittin on both gastric and colorectal cancer, specifically AGS, COLO205 and HCT-15 cell lines, over a period of 15 minutes. Melittin exhibited a dose dependent effect at 4 hours of treatment, with complete cellular death occurring at the highest dose of 20 μg/mL. Interestingly, when observed at shorter time points, melittin induced cellular changes within seconds; membrane damage was observed as swelling, breakage or blebbing. High-resolution imaging revealed treated cells to be compromised, showing clear change in cellular morphology. After 1 minute of melittin treatment, membrane changes were observed, and intracellular material could be seen expelled from the cells. Overall, these results enhance our understanding of the fast acting anti-cancer effects of melittin.

The Place for Enzymes and Biologically Active Peptides from Marine Organisms for Application in Industrial and Pharmaceutical Biotechnology

Since the beginning of written history, diverse texts have reported the use of enzymatic preparations in food processing and have described the medicinal properties of crude and fractionated venoms to treat various diseases and injuries. With the biochemical characterization of enzymes from distinct sources and bioactive polypeptides from animal venoms, the last sixty years have testified the advent of industrial enzymology and protein therapeutics, which are currently applicable in a wide variety of industrial processes, household products, and pharmaceuticals. Bioprospecting of novel biocatalysts and bioactive peptides is propelled by their unsurpassed properties that are applicable for current and future green industrial processes, biotechnology, and biomedicine. The demand for both novel enzymes with desired characteristics and novel peptides that lead to drug development, has experienced a steady increase in response to the expanding global market for industrial enzymes and peptidebased drugs. Moreover, although largely unexplored, oceans and marine realms, with their unique ecosystems inhabited by a large variety of species, including a considerable number of venomous animals, are recognized as untapped reservoirs of molecules and macromolecules (enzymes and bioactive venom-derived peptides) that can potentially be converted into highly valuable biopharmaceutical products. In this review, we have focused on enzymes and animal venom (poly)peptides that are presently in biotechnological use, and considering the state of prospection of marine resources, on the discovery of useful industrial biocatalysts and drug leads with novel structures exhibiting selectivity and improved performance.

Self-assembling peptide-based nanodrug delivery systems

Self-assembling peptide-based nanodrug delivery systems (NDDs), consisting of naturally occurring amino acids, not only share the advantages of traditional nanomedicine but also possess the unique properties of excellent biocompatibility, biodegradability, flexible responsiveness, specific biological function, and synthetic feasibility. Physical methods, enzymatic reaction, chemical reaction, and biosurface induction can yield versatile peptide-based NDDs; flexible responsiveness is their main advantage. Different functional peptides and abundant covalent modifications endow such systems with precise controllability and multifunctionality. Inspired by the above merits, researchers have taken advantage of the self-assembling peptide-based NDDs and achieved the accurate delivery of drugs to the lesion site. The present review outlines the methods for designing self-assembling peptide-based NDDs for small-molecule drugs, with an emphasis on the different drug delivery strategies and their applications in using peptides and peptide conjugates.

Bee Venom: Overview of Main Compounds and Bioactivities for Therapeutic Interests

Apitherapy is an alternate therapy that relies on the usage of honeybee products, most importantly bee venom for the treatment of many human diseases. The venom can be introduced into the human body by manual injection or by direct bee stings. Bee venom contains several active molecules such as peptides and enzymes that have advantageous potential in treating inflammation and central nervous system diseases, such as Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis. Moreover, bee venom has shown promising benefits against different types of cancer as well as anti-viral activity, even against the challenging human immunodeficiency virus (HIV). Many studies described biological activities of bee venom components and launched preclinical trials to improve the potential use of apitoxin and its constituents as the next generation of drugs. The aim of this review is to summarize the main compounds of bee venom, their primary biological properties, mechanisms of action, and their therapeutic values in alternative therapy strategies.

Synergistic Effects of Melittin and Plasma Treatment: A Promising Approach for Cancer Therapy

Melittin (MEL), a small peptide component of bee venom, has been reported to exhibit anti-cancer effects in vitro and in vivo. However, its clinical applicability is disputed because of its non-specific cytotoxicity and haemolytic activity in high treatment doses. Plasma-treated phosphate buffered saline solution (PT-PBS), a solution rich in reactive oxygen and nitrogen species (RONS) can disrupt the cell membrane integrity and induce cancer cell death through oxidative stress-mediated pathways. Thus, PT-PBS could be used in combination with MEL to facilitate its access into cancer cells and to reduce the required therapeutic dose. The aim of our study is to determine the reduction of the effective dose of MEL required to eliminate cancer cells by its combination with PT-PBS. For this purpose, we have optimised the MEL threshold concentration and tested the combined treatment of MEL and PT-PBS on A375 melanoma and MCF7 breast cancer cells, using in vitro, in ovo and in silico approaches. We investigated the cytotoxic effect of MEL and PT-PBS alone and in combination to reveal their synergistic cytological effects. To support the in vitro and in ovo experiments, we showed by computer simulations that plasma-induced oxidation of the phospholipid bilayer leads to a decrease of the free energy barrier for translocation of MEL in comparison with the non-oxidized bilayer, which also suggests a synergistic effect of MEL with plasma induced oxidation. Overall, our findings suggest that MEL in combination with PT-PBS can be a promising combinational therapy to circumvent the non-specific toxicity of MEL, which may help for clinical applicability in the future.

Analgesic Effect of Melittin on Oxaliplatin-Induced Peripheral Neuropathy in Rats

Oxaliplatin is a chemotherapeutic agent used for metastatic colon and other advanced cancers. Most common side effect of oxaliplatin is peripheral neuropathy, manifested in mechanical and cold allodynia. Although the analgesic effect of bee venom has been proven to be effective against oxaliplatin-induced peripheral neuropathy, the effect of its major component; melittin has not been studied yet. Thus, in this study, we investigated whether melittin has an analgesic effect on oxaliplatin-induced allodynia. Intraperitoneal single injection of oxaliplatin (6 mg/kg) induced mechanical and cold allodynia, resulting in increased withdrawal behavior in response to von Frey filaments and acetone drop on hind paw. Subcutaneous melittin injection on acupoint ST36 (0.5 mg/kg) alleviated oxaliplatin-induced mechanical and cold allodynia. In electrophysiological study, using spinal in vivo extracellular recording, it was shown that oxaliplatin-induced hyperexcitation of spinal wide dynamic range neurons in response to peripheral stimuli, and melittin administration inhibited this neuronal activity. In behavioral assessment, analgesic effect of melittin was blocked by intrathecal α1- and α2- adrenergic receptor antagonists administration. Based on these results, we suggest that melittin could be used as an analgesic on oxaliplatin-induced peripheral neuropathy, and that its effect is mediated by activating the spinal α1- and α2-adrenergic receptors.

Potential Therapeutic Applications of Bee Venom on Skin Disease and Its Mechanisms: A Literature Review

Skin is larger than any other organ in humans. Like other organs, various bacterial, viral, and inflammatory diseases, as well as cancer, affect the skin. Skin diseases like acne, atopic dermatitis, and psoriasis often reduce the quality of life seriously. Therefore, effective treatment of skin disorders is important despite them not being life-threatening. Conventional medicines for skin diseases include corticosteroids and antimicrobial drugs, which are effective in treating many inflammatory and infectious skin diseases; however, there are growing concerns about the side effects of these therapies, especially during long-term use in relapsing or intractable diseases. Hence, many researchers are trying to develop alternative treatments, especially from natural sources, to resolve these limitations. Bee venom (BV) is an attractive candidate because many experimental and clinical reports show that BV exhibits anti-inflammatory, anti-apoptotic, anti-fibrotic, antibacterial, antiviral, antifungal, and anticancer effects. Here, we review the therapeutic applications of BV in skin diseases, including acne, alopecia, atopic dermatitis, melanoma, morphea, photoaging, psoriasis, wounds, wrinkles, and vitiligo. Moreover, we explore the therapeutic mechanisms of BV in the treatment of skin diseases and killing effects of BV on skin disease-causing pathogens, including bacteria, fungi and viruses.

Nanoparticles Functionalized with Venom-Derived Peptides and Toxins for Pharmaceutical Applications

Venom-derived peptides display diverse biological and pharmacological activities, making them useful in drug discovery platforms and for a wide range of applications in medicine and pharmaceutical biotechnology. Due to their target specificities, venom peptides have the potential to be developed into biopharmaceuticals to treat various health conditions such as diabetes mellitus, hypertension, and chronic pain. Despite the high potential for drug development, several limitations preclude the direct use of peptides as therapeutics and hamper the process of converting venom peptides into pharmaceuticals. These limitations include, for instance, chemical instability, poor oral absorption, short halflife, and off-target cytotoxicity. One strategy to overcome these disadvantages relies on the formulation of bioactive peptides with nanocarriers. A range of biocompatible materials are now available that can serve as nanocarriers and can improve the bioavailability of therapeutic and venom-derived peptides for clinical and diagnostic application. Examples of isolated venom peptides and crude animal venoms that have been encapsulated and formulated with different types of nanomaterials with promising results are increasingly reported. Based on the current data, a wealth of information can be collected regarding the utilization of nanocarriers to encapsulate venom peptides and render them bioavailable for pharmaceutical use. Overall, nanomaterials arise as essential components in the preparation of biopharmaceuticals that are based on biological and pharmacological active venom-derived peptides.

Rational Design of Hybrid Peptides: A Novel Drug Design Approach

Peptides play crucial roles in various physiological and pathological processes. Consequently, the investigation of peptide-based drugs is a highlight in the research and development of new drugs. However, natural peptides are not always ideal choices for clinical application due to their limited number and sometimes cytotoxicity to normal cells. Aiming to gain stronger or specific or novel biological effects and overcome the disadvantages of natural peptides, artificial hybrid peptides have been designed by combining the sequence of two or more different peptides with varied biological functions. Compared to natural peptides, hybrid peptides have shown better therapeutic potentials against bacteria, tumors, and metabolic diseases. In this review, design strategies, structure features and recent development of hybrid peptides are summarized; future directions for the research and development of hybrid peptide drugs are also discussed.

Antimicrobial Peptides: Potential Application in Liver Cancer

The physicochemical properties of antimicrobial peptides (AMPs) including size, net charge, amphipathic structure, hydrophobicity, and mode-of-action together determine their broad-spectrum activities against bacteria, fungi, protozoa, and viruses. Recent studies show that some AMPs have both antimicrobial and anticancer activities, suggesting a new strategy for cancer therapy. Hepatocellular carcinoma (HCC), the primary liver cancer, is a leading cause of cancer mortality worldwide, and lacks effective treatment. Anticancer peptides (ACPs) derived from AMPs or natural resources could be applied to combat HCC directly or as a synergistic treatment. However, the number of known ACPs is low compared to the number of antibacterial and antifungal peptides, and very few of them can be applied clinically for HCC treatment. In this review, we first summarize recent studies related to ACPs for HCC, followed by a description of potential modes-of-action including direct killing, anti-inflammation, immune modulation, and enhanced wound healing. We then describe the structures of AMPs and methods to design and modify these peptides to improve their anticancer efficacy. Finally, we explore the potential application of ACPs as vaccines or nanoparticles for HCC treatment. Overall, ACPs display several attractive properties as therapeutic agents, including broad-spectrum anticancer activity, ease-of-design and modification, and low production costs. As this is an emerging and novel area of cancer therapy, additional studies are needed to identify existing candidate AMPs with ACP activity, and assess their anticancer activity and specificity, and immunomodulatory effects, using in vitro, in silico, and in vivo approaches.

A Unique Family of Neuronal Signaling Proteins Implicated in Oncogenesis and Tumor Suppression

The neuronal proteins GAP43 (neuromodulin), MARCKS, and BASP1 are highly expressed in the growth cones of nerve cells where they are involved in signal transmission and cytoskeleton organization. Although their primary structures are unrelated, these signaling proteins share several structural properties like fatty acid modification, and the presence of cationic effector domains. GAP43, MARCKS, and BASP1 bind to cell membrane phospholipids, a process reversibly regulated by protein kinase C-phosphorylation or by binding to the calcium sensor calmodulin (CaM). GAP43, MARCKS, and BASP1 are also expressed in non-neuronal cells, where they may have important functions to manage cytoskeleton architecture, and in case of MARCKS and BASP1 to act as cofactors in transcriptional regulation. During neoplastic cell transformation, the proteins reveal differential expression in normal vs. tumor cells, and display intrinsic tumor promoting or tumor suppressive activities. Whereas GAP43 and MARCKS are oncogenic, tumor suppressive functions have been ascribed to BASP1 and in part to MARCKS depending on the cell type. Like MARCKS, the myristoylated BASP1 protein is localized both in the cytoplasm and in the cell nucleus. Nuclear BASP1 participates in gene regulation converting the Wilms tumor transcription factor WT1 from an oncoprotein into a tumor suppressor. The BASP1 gene is downregulated in many human tumor cell lines particularly in those derived from leukemias, which display elevated levels of WT1 and of the major cancer driver MYC. BASP1 specifically inhibits MYC-induced cell transformation in cultured cells. The tumor suppressive functions of BASP1 and MARCKS could be exploited to expand the spectrum of future innovative therapeutic approaches to inhibit growth and viability of susceptible human tumors.

Dose-Dependent Neuroprotective Effect of Standardized Bee Venom Phospholipase A2 Against MPTP-Induced Parkinson's Disease in Mice

Parkinson’s disease (PD) is a chronic progressive neurodegenerative movement disorder characterized by the selective loss of dopaminergic neurons within the substantia nigra (SN). While the precise etiology of dopaminergic neuronal demise is elusive, multiple lines of evidence indicate that neuroinflammation is involved in the pathogenesis of PD. We have previously demonstrated that subcutaneous administration of bee venom (BV) phospholipase A₂ (bvPLA₂) suppresses dopaminergic neuronal cell death in a PD mouse model. In the present study, we established standardized methods for producing bvPLA₂ agent isolated from crude BV at good manufacturing practice (GMP) facility. The therapeutic efficacy of purified bvPLA2 agent was examined in MPTP-induced PD mice. Importantly, administration of purified bvPLA₂ in a dose-dependent manner reversed motor deficits in PD mice as well as inhibited loss of dopaminergic neurons within the SN of PD mice. The concentration-dependent action of standardized bvPLA₂ appeared to be related to the induction of CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Tregs), which, in part, inhibits T helper 1 (Th1) and Th17 polarization and suppresses microglial activation in PD mice. Taken together, these results suggest that standardized bvPLA₂ purified from BV shows a neuroprotective effect against PD and thus has a potential target for treatment of PD.

Melittin Inhibits Hypoxia-Induced Vasculogenic Mimicry Formation and Epithelial-Mesenchymal Transition through Suppression of HIF-1α/Akt Pathway in Liver Cancer

In this study, we investigated whether melittin could suppress hypoxia-induced vasculogenic mimicry (VM) formation in liver cancer and explored the underlying mechanisms. Melittin significantly inhibited the proliferation of liver cancer cells with or without CoCl₂ presence. Melittin also significantly inhibited CoCl₂-induced migration, invasion, and VM formation of liver cancer cells. CoCl₂ treatment suppressed the expression of E-cadherin and elevated the expression of N-cadherin and Vimentin. Melittin reversed the changes in the protein and mRNA levels of these epithelial-mesenchymal transition (EMT) markers. CoCl₂-induced accumulation of HIF-1α increased the level of phosphorylated Akt and upregulated the expression of VEGF and MMP-2/9. Melittin decreased the HIF-1α level and thereby suppressed the levels of p-Akt, VEGF, and MMP-2/9. In addition, the inhibitor of PI3K/Akt also suppressed CoCl₂-induced EMT and liver cancer cells migration, and the activator of Akt, SC-79, partly blocked the effect of melittin on CoCl₂-induced EMT and liver cancer cells migration. In the xenograft tumor model in nude mice, melittin treatment significantly suppressed the tumor growth, VM formation, and HIF-1α expression in the tumor. In conclusion, this study indicates melittin may inhibit hypoxia-induced VM formation and EMT in liver cancer through inhibiting HIF-1α/Akt pathway.

Involvement of the anti-inflammatory, anti-apoptotic, and anti-secretory activity of bee venom in its therapeutic effects on acetylsalicylic acid-induced gastric ulceration in rats

Acetylsalicylic acid (ASA) is the most highly consumed pharmaceutical product worldwide. Importantly, gastrointestinal ulceration due to ASA is a major complication. Hence, the present work aimed to examine, for the first time, the healing properties of bee venom (BV) in acute gastric ulceration induced by ASA. Forty adult male Sprague-Dawley rats were divided into four groups that received distilled water only, ASA (500 mg/kg BW) twice daily for 3 days, ASA for 3 days followed by BV (2 mg/kg BW) for 7 days, or ASA for 3 days followed by ranitidine hydrochloride (50 mg/kg BW) for 7 days. Haematological analysis, haemostatic evaluation, and inflammatory marker estimation were performed. Rat stomachs were collected for ulcer scoring, gene expression analysis, oxidative stress assays, histopathological and immunohistochemical examinations, and tissue eosinophil scoring. The results revealed that BV markedly decreased the ulcer index, pro-inflammatory cytokine levels, malondialdehyde levels, BAX distribution, caspase-3 expression, and tissue eosinophil levels. Additionally, significant increases in antioxidant enzymes and heat shock protein 70 localization in gastric tissue were evident following BV treatment after ASA exposure. Also, BV has been found to attenuate the haematological, haemostatic, and histopathological alterations induced by ASA. Our findings collectively indicate that the gastroprotective effect of BV against ASA-induced ulceration in rats is mediated by its antioxidant, anti-inflammatory, anti-apoptotic, and anti-secretory properties.

Bee Venom and Its Peptide Component Melittin Suppress Growth and Migration of Melanoma Cells via Inhibition of PI3K/AKT/mTOR and MAPK Pathways

Malignant melanoma is the deadliest form of skin cancer and highly chemoresistant. Melittin, an amphiphilic peptide containing 26 amino acid residues, is the major active ingredient from bee venom (BV). Although melittin is known to have several biological activities such as anti-inflammatory, antibacterial and anticancer effects, its antimelanoma effect and underlying molecular mechanism have not been fully elucidated. In the current study, we investigated the inhibitory effect and action mechanism of BV and melittin against various melanoma cells including B16F10, A375SM and SK-MEL-28. BV and melittin potently suppressed the growth, clonogenic survival, migration and invasion of melanoma cells. They also reduced the melanin formation in α-melanocyte-stimulating hormone (MSH)-stimulated melanoma cells. Furthermore, BV and melittin induced the apoptosis of melanoma cells by enhancing the activities of caspase-3 and -9. In addition, we demonstrated that the antimelanoma effect of BV and melittin is associated with the downregulation of PI3K/AKT/mTOR and MAPK signaling pathways. We also found that the combination of melittin with the chemotherapeutic agent temozolomide (TMZ) significantly increases the inhibition of growth as well as invasion in melanoma cells compared to melittin or TMZ alone. Taken together, these results suggest that melittin could be potentially applied for the prevention and treatment of malignant melanoma.

Top-down Multiscale Approach To Simulate Peptide Self-Assembly from Monomers

Modeling peptide assembly from monomers on large time and length scales is often intractable at the atomistic resolution. To address this challenge, we present a new approach which integrates coarse-grained (CG), mixed-resolution, and all-atom (AA) modeling in a single simulation. We simulate the initial encounter stage with the CG model, while the further assembly and reorganization stages are simulated with the mixed-resolution and AA models. We have implemented this top-down approach with new tools to automate model transformations and to monitor oligomer formations. Further, a theory was developed to estimate the optimal simulation length for each stage using a model peptide, melittin. The assembly level, the oligomer distribution, and the secondary structures of melittin simulated by the optimal protocol show good agreement with prior experiments and AA simulations. Finally, our approach and theory have been successfully validated with three amyloid peptides (β-amyloid 16-22, GNNQQNY fragment from the yeast prion protein SUP35, and α-synuclein fibril 35-55), which highlight the synergy from modeling at multiple resolutions. This work not only serves as proof of concept for multiresolution simulation studies but also presents practical guidelines for further self-assembly simulations at more physically and chemically relevant scales.

Smart aptamer-modified calcium carbonate nanoparticles for controlled release and targeted delivery of epirubicin and melittin into cancer cells in vitro and in vivo

To explore the effect of combination therapy of epirubicin (Epi) and melittin (Mel) to cancer cells, calcium carbonate nanoparticles (CCN), as carriers, were developed which were modified with MUC1-Dimer aptamers as targeting agents. Both Epi and Mel were delivered at the same time to cancer cells overexpressing the target of MUC1 aptamer, mucin 1 glycoproteins (MCF7 and C26 cells). CCN were prepared with a water-in-oil emulsion method. Epi and Mel were separately encapsulated in CCN and the nanoparticles were modified with MUC1-Dimer aptamers. In vitro studies, including MTT assay, flow cytometry analysis and fluorescence imaging were applied to investigate the targeting and cell proliferation inhibition capabilities of MUC1-Dimer aptamer-CCN-Mel complex and MUC1-Dimer aptamer-CCN-Epi complex in the target (MCF-7 and C26 cells) and nontarget (HepG2) cells. Also, the function of the developed complexes was analyzed using in vivo tumor growth inhibition. The release of Epi from MUC1-Dimer aptamer-CCN-Epi complex was pH-sensitive. Cellular uptake studies showed more internalization of the MUC1-Dimer aptamer-CCN-Epi complex into MCF-7 and C26 cells (target) compared to HepG2 cells (nontarget). Interestingly, the MUC1-Dimer aptamer-CCN-Mel complex and MUC1-Dimer aptamer-CCN-Epi complex indicated very low toxicity as compared to target cells. Moreover, co-delivery of Epi and Mel using the mixture of MUC1-Dimer aptamer-CCN-Mel complex and MUC1-Dimer aptamer-CCN-Epi complex exhibited strong synergistic cytotoxicity in MCF-7 and C26 cells. Furthermore, the presented complexes had a better function to control tumor growth in vivo compared to free Epi.

Helical Structure of Recombinant Melittin

Melittin is an extensively studied, 26-residue toxic peptide from honey bee venom. Because of its versatility in adopting a variety of secondary (helix or coil) and quaternary (monomer or tetramer) structures in various environments, melittin has been the focus of numerous investigations as a model peptide in protein folding studies as well as in studies involving binding to proteins, lipids, and polysaccharides. A significant body of evidence supports the view that melittin binds to these macromolecules in a predominantly helical conformation, but detailed structural knowledge of this conformation is lacking. In this report, we present nuclear magnetic resonance (NMR)-based structural insights into the helix formation of recombinant melittin in the presence of trifluoroethanol (TFE): a known secondary structure inducer in peptides. These studies were performed at neutral pH, with micromolar amounts of the peptide. Using nuclear Overhauser effect (NOE)-derived distance restraints from three-dimensional NMR spectra, we determined the atomic resolution solution NMR structure of recombinant melittin bearing a TFE-stabilized helix. To circumvent the complications with structure determination of small peptides with high conformational flexibility, we developed a workflow for enhancing proton NOEs by increasing the viscosity of the medium. In the TFE-containing medium, recombinant monomeric melittin forms a long, continuous helical structure, which consists of the N- and C-terminal α-helices and the noncanonical 3₁₀-helix in the middle. The noncanonical 3₁₀-helix is missing in the previously solved X-ray structure of tetrameric melittin and the NMR structure of melittin in methanol. Melittin's structure in TFE-containing medium provides insights into melittin's conformational transitions, which are relevant to the peptide's interactions with its biological targets.

Melittin Induced G1 Cell Cycle Arrest and Apoptosis in Chago-K1 Human Bronchogenic Carcinoma Cells and Inhibited the Differentiation of THP-1 Cells into Tumour- Associated Macrophages

Background: Bronchogenic carcinoma (lung cancer) is one of the leading causes of death. Although many compounds isolated from natural products have been used to treat it, drug resistance is a serious problem, and alternative anti-cancer drugs are required. Here, melittin from Apis mellifera venom was used, and its effects on bronchogenic carcinoma cell proliferation and tumour-associated macrophage differentiation were evaluated. Methods: The half maximal inhibitory concentration (IC50) of melittin was measured by MTT. Cell death was observed by annexin V and propidium iodide (PI) co-staining followed by flow cytometry. Cell cycle arrest was revealed by PI staining and flow cytometry. To investigate the tumour microenvironment, differentiation of circulating monocytes (THP-1) into tumour-associated macrophages (TAMs) was assayed by sandwich-ELISA and interleukin (IL)-10 levels were determined. Cell proliferation and migration was observed by flat plate colony formation. Secretion of vascular endothelial growth factor (VEGF) was detected by ELISA. The change in expression levels of CatS, Bcl-2, and MADD was measured by quantitative RT-PCR. Results: Melittin was significantly more cytotoxic (p < 0.01) to human bronchogenic carcinoma cells (ChaGo-K1) than to the control human lung fibroblasts (Wi-38) cells. At 2.5 μM, melittin caused ChaGo-K1 cells to undergo apoptosis and cell cycle arrest at the G1 phase. The IL-10 levels showed that melittin significantly inhibited the differentiation of THP-1 cells into TAMs (p < 0.05) and reduced the number of colonies formed in the treated ChaGo-K1 cells compared to the untreated cells. However, melittin did not affect angiogenesis in ChaGo-K1 cells. Unlike MADD, Bcl-2 was up-regulated significantly (p < 0.05) in melittin-treated ChaGo-K1 cells. Conclusion: Melittin can be used as an alternative agent for lung cancer treatment because of its cytotoxicity against ChaGo-K1 cells and the inhibition of differentiation of THP-1 cells into TAMs.

Anticancer Activity of the Goat Antimicrobial Peptide ChMAP-28

Cytotoxic effect of the antimicrobial peptide ChMAP-28 from leucocytes of the goat Capra hircus was examined against five cancer and two normal human cell lines. ChMAP-28 has the amino acid sequence GRFKRFRKKLKRLWHKVGPFVGPILHY and is homologous to other α-helical mammalian antimicrobial peptides. ChMAP-28 shows considerably higher cytotoxicity against cultured tumor cells than toward normal cells at concentrations of <10 μM. Our findings suggest that ChMAP-28 can initiate necrotic death of cancer cells. Its cytotoxic effect is accomplished due to disruption of the plasma membrane integrity and is not abrogated by the addition of the caspase inhibitor Z-VAD-FMK. ChMAP-28 causes permeabilization of cytoplasmic membrane of human leukemia cells HL-60 already after 15 min of incubation. Here, we show that ChMAP-28 has one of the highest antitumor activity in vitro among all known antimicrobial peptides. We speculate that the observed specificity of ChMAP-28 cytotoxic effect against tumor cells is due to its relatively low hydrophobicity and high cationicity. In the meantime, this peptide has low hemolytic activity, which generates a potential for its use as a therapeutic agent.

Synergistic co-delivery of doxorubicin and melittin using functionalized magnetic nanoparticles for cancer treatment: loading and in vitro release study by LC-MS/MS

In this study, citric acid-functionalized Fe₃O₄ magnetic nanoparticles (CA-MNPs) were prepared via a coprecipitation method and were fully characterized. Doxorubicin (DOX) and melittin (MEL), as anticancer agents, were loaded onto CA-MNPs surface through electrostatic interactions with the aim to achieve an effective co-delivery system for cancer therapy. The loading efficiency and in vitro release profiles of DOX and MEL were investigated by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The MS/MS step was performed in the selected reaction monitoring (SRM) mode which enabled simultaneous quantification of the analytes with high specificity and sensitivity. An excellent loading efficiency of about 100% was achieved for DOX and MEL in a drug to nanocarrier ratio of 1:10. The in vitro release of the drugs from CA-MNPs was evaluated for 8 h at pH 7.4, 5.5 and 4.5. The experimental results revealed that the release behaviour of both of the anticancer agents was strongly pH-dependent and significantly enhanced at pH 4.5. The in vitro MTT assay on MCF-7 breast cancer cell line exhibited a synergistic effect between DOX and MEL which led to substantially greater antitumor efficacy, compared to single administration of these anticancer agents at equivalent doses. The results indicated that the co-delivery system of (DOX/MEL)-loaded CA-MNPs is highly capable to be used in magnetically targeted cancer therapy.

Insect Antimicrobial Peptides, a Mini Review

Antimicrobial peptides (AMPs) are crucial effectors of the innate immune system. They provide the first line of defense against a variety of pathogens. AMPs display synergistic effects with conventional antibiotics, and thus present the potential for combined therapies. Insects are extremely resistant to bacterial infections. Insect AMPs are cationic and comprise less than 100 amino acids. These insect peptides exhibit an antimicrobial effect by disrupting the microbial membrane and do not easily allow microbes to develop drug resistance. Currently, membrane mechanisms underlying the antimicrobial effects of AMPs are proposed by different modes: the barrel-stave mode, toroidal-pore, carpet, and disordered toroidal-pore are the typical modes. Positive charge quantity, hydrophobic property and the secondary structure of the peptide are important for the antibacterial activity of AMPs. At present, several structural families of AMPs from insects are known (defensins, cecropins, drosocins, attacins, diptericins, ponericins, metchnikowins, and melittin), but new AMPs are frequently discovered. We reviewed the biological effects of the major insect AMPs. This review will provide further information that facilitates the study of insect AMPs and shed some light on novel microbicides.

Therapeutic strategies to target microbial protein-glycosaminoglycan interactions

Glycans are involved in a plethora of human pathologies including infectious diseases. Especially, glycosaminoglycans (GAGs), like heparan sulfate and chondroitin sulfate, have been found to be involved in different crucial stages of microbial invasion. Here, we review various therapeutic approaches, which target the interface of host GAGs and microbial proteins and discuss their limitations and challenges for drug development.

Effect of Melittin on Metabolomic Profile and Cytokine Production in PMA-Differentiated THP-1 Cells

Melittin, the major active peptide of honeybee venom (BV), has potential for use in adjuvant immunotherapy. The immune system response to different stimuli depends on the secretion of different metabolites from macrophages. One potent stimulus is lipopolysaccharide (LPS), a component isolated from gram-negative bacteria, which induces the secretion of pro-inflammatory cytokines in macrophage cell cultures. This secretion is amplified when LPS is combined with melittin. In the present study, pure melittin was isolated from whole BV by flash chromatography to obtain pure melittin. The ability of melittin to enhance the release of tumour necrosis factor-α (TNF-α), Interleukin (IL-1β, IL-6, and IL-10) cytokines from a macrophage cell line (THP-1) was then assessed. The response to melittin and LPS, applied alone or in combination, was characterised by metabolic profiling, and the metabolomics results were used to evaluate the potential of melittin as an immune adjuvant therapy. The addition of melittin enhanced the release of inflammatory cytokines induced by LPS. Effective chromatographic separation of metabolites was obtained by liquid chromatography-mass spectrometry (LC-MS) using a ZIC-pHILIC column and an ACE C4 column. The levels of 108 polar and non-polar metabolites were significantly changed (p ˂ 0.05) following cell activation by the combination of LPS and melittin when compared to untreated control cells. Overall, the findings of this study suggested that melittin might have a potential application as a vaccine adjuvant.

To bee or not to bee: The potential efficacy and safety of bee venom acupuncture in humans

Bee venom acupuncture is a form of acupuncture in which bee venom is applied to the tips of acupuncture needles, stingers are extracted from bees, or bees are held with an instrument exposing the stinger, and applied to acupoints on the skin. Bee venom is a complex substance consisting of multiple anti-inflammatory compounds such as melittin, adolapin, apamin. Other substances such as phospholipase A2 can be anti-inflammatory in low concentrations and pro-inflammatory in others. However, bee venom also contains proinflammatory substances, melittin, mast cell degranulation peptide 401, and histamine. Nevertheless, in small studies, bee venom acupuncture has been used in man to successfully treat a number of musculoskeletal diseases such as lumbar disc disease, osteoarthritis of the knee, rheumatoid arthritis, adhesive capsulitis, and lateral epicondylitis. Bee venom acupuncture can also alleviate neurological conditions, including peripheral neuropathies, stroke and Parkinson's Disease. The treatment has even been piloted in one series to alleviate depression. An important concern is the safety of bee venom. Bee venom can cause anaphylaxis, and several deaths have been reported in patients who successfully received the therapy prior to the adverse event. While the incidence of adverse events is unknown, the number of published reports of toxicity is small. Refining bee venom to remove harmful substances may potentially limit its toxicity. New uses for bee venom acupuncture may also be considered.

Melittin induces NSCLC apoptosis via inhibition of miR-183

Background

Non-small-cell lung cancer (NSCLC) has one of the highest mortality rates among cancers worldwide, with a poor prognosis. Previous studies have reported that melittin, an active component of apitoxin, exerts anti-inflammatory and antitumor effects via vascular endothelial growth factor or FoxO1.

Methods

CCK8, flow cytometry assay and Western blotting were performed to evaluate the effect of melittin on NSCLC.

Results

The present study demonstrates that melittin activated caspase-2 by inhibiting miR-183 expression and, thus, induced NSCLC apoptosis in both NCI-H441 cancer cell line assays and an in vivo xenograft model. The results of the cell-based assays showed that melittin (2 μg/mL) robustly suppressed miR-183 expression level and resulted in decreased invasion and migration abilities of NCI-H441 cells. Additionally, a flow cytometry assay and Western blotting showed that melittin induced NSCLC NCI-H441 cell apoptosis along with significant elevation of caspase-2 and Bax, which are regulators of cell apoptosis, and reduced Bcl-2 protein expression compared with dimethyl sulfoxide control. Furthermore, subcutaneous injection of melittin (5 mg/kg) significantly suppressed NSCLC tumor growth compared with vehicle group tumors, determined through tumor size and weight.

Conclusion

Taken together, the aforementioned findings contribute to identification of a novel therapeutic target in the treatment of NSCLC, in patients diagnosed with a high expression of miR-183. Moreover, this article provides solid evidence for the inhibitory effect of melittin on NSCLC cancer cell growth.

Turning Toxicants into Safe Therapeutic Drugs: Cytolytic Peptide-Photosensitizer Assemblies for Optimized In Vivo Delivery of Melittin

Melittin (MEL) is recognized as a highly potent therapeutic peptide for treating various human diseases including cancer. However, the clinical applications of MEL are largely restricted by its severe hemolytic activity and nonspecific cytotoxicity. Here, it is found that MEL can form a stable supramolecular nanocomplex of ≈60 nm with the photosensitizer chlorin e6 (Ce6), which after hyaluronic acid (HA) coating can achieve robust, safe, and imaging-guided tumor ablation. The as-designed nanocomplex (denoted as MEL/Ce6@HA) shows largely reduced hemolysis and selective cytolytic activity toward cancer cells. Upon laser irradiation, the loaded photosensitive Ce6 can synergistically facilitate the membrane-lytic efficiency of melittin and greatly increase the tumor penetration depth of the complexes in multicellular tumor spheroids. In vivo experiments reveal that MEL/Ce6@HA can realize enhanced tumor accumulation, reduced liver deposition, and rapid body clearance, which are beneficial for highly efficient and safe chemo-photodynamic dual therapy. This work develops a unique supramolecular strategy for optimized in vivo delivery of melittin and may have implications for the development of peptide-based theranostics.

Anticancer Properties of Graviola (Annona muricata): A Comprehensive Mechanistic Review

Graviola (Annona muricata) is a small deciduous tropical evergreen fruit tree, belonging to the Annonaceae family, and is widely grown and distributed in tropical and subtropical regions around the world. The aerial parts of graviola have several functions: the fruits have been widely used as food confectionaries, while several preparations, especially decoctions of the bark, fruits, leaves, pericarp, seeds, and roots, have been extensively used in traditional medicine to treat multiple ailments including cancers by local communities in tropical Africa and South America. The reported therapeutic benefits of graviola against various human tumors and disease agents in in vitro culture and preclinical animal model systems are typically tested for their ability to specifically target the disease, while exerting little or no effect on normal cell viability. Over 212 phytochemical ingredients have been reported in graviola extracts prepared from different plant parts. The specific bioactive constituents responsible for the major anticancer, antioxidant, anti-inflammatory, antimicrobial, and other health benefits of graviola include different classes of annonaceous acetogenins (metabolites and products of the polyketide pathway), alkaloids, flavonoids, sterols, and others. This review summarizes the current understanding of the anticancer effects of A. muricata and its constituents on diverse cancer types and disease states, as well as efficacy and safety concerns. It also includes discussion of our current understanding of possible mechanisms of action, with the hope of further stimulating the development of improved and affordable therapies for a variety of ailments.

Antioxidant, antihyperglycemic, and antidiabetic activity of Apis mellifera bee tea

Diabetes has emerged as one of the largest global epidemics; it is estimated that by 2035, there will be 592 million diabetic people in the world. Brazilian biodiversity and the knowledge of traditional peoples have contributed to the treatment of several diseases, including diabetes. Apis mellifera bee tea is used by indigenous Brazilians to treat diabetes, and this traditional knowledge needs to be recorded and studied.The objective of this study was to record the use and to evaluate the antioxidant, antihyperglycemic, and antidiabetic activity of Apis mellifera bee tea, which is used by the Guarani and Kaiowá indigenous people for the treatment of diabetes. Semi-structured interviews were performed with Guarani and Kaiowá ethnic indigenous people from the State of Mato Grosso do Sul, Brazil, seeking to identify the animal species used for medicinal purposes. For the experimental procedures, tea prepared with macerated Apis mellifera bees was used. In vitro assays were performed to evaluate antioxidant activity; direct free radical scavenging, protection against oxidative hemolysis, lipid peroxidation were evaluated in human erythrocytes and potential in inhibiting the formation of advanced glycation end products (AGEs). In vivo, normoglycemic Swiss male mice treated with Apis mellifera tea (AmT) were subjected to the oral glucose tolerance test and compared with control and metformin-treated groups. Diet-induced diabetic mice were treated for 21 days with AmT and evaluated for glycemia and malondialdehyde levels in the blood, liver, nervous system, and eyes. During interviews, the indigenous people described the use of Apis mellifera bee tea for the treatment of diabetes. In in vitro assays, AmT showed direct antioxidant activity and reduced oxidative hemolysis and malondialdehyde generation in human erythrocytes. The AmT inhibited the formation of AGEs by albumin-fructose pathways and methylglyoxal products. In vivo, after oral glucose overload, normoglycemic mice treated with AmT had reduced hyperglycemia at all times evaluated up to 180 min. AmT also reduced hyperglycemia and malondialdehyde levels in the blood, liver, nervous system, and eyes of diabetic mice to similar levels as those in metformin-treated mice and normoglycemic controls. In summary, Apis mellifera bee tea showed antioxidant, antihyperglycemic, and antidiabetic activity, which provides support for the therapeutic application of Guarani and Kaiowá indigenous knowledge.

Exploring Molecular-Biomembrane Interactions with Surface Plasmon Resonance and Dual Polarization Interferometry Technology: Expanding the Spotlight onto Biomembrane Structure

The molecular analysis of biomolecular-membrane interactions is central to understanding most cellular systems but has emerged as a complex technical challenge given the complexities of membrane structure and composition across all living cells. We present a review of the application of surface plasmon resonance and dual polarization interferometry-based biosensors to the study of biomembrane-based systems using both planar mono- or bilayers or liposomes. We first describe the optical principals and instrumentation of surface plasmon resonance, including both linear and extraordinary transmission modes and dual polarization interferometry. We then describe the wide range of model membrane systems that have been developed for deposition on the chips surfaces that include planar, polymer cushioned, tethered bilayers, and liposomes. This is followed by a description of the different chemical immobilization or physisorption techniques. The application of this broad range of engineered membrane surfaces to biomolecular-membrane interactions is then overviewed and how the information obtained using these techniques enhance our molecular understanding of membrane-mediated peptide and protein function. We first discuss experiments where SPR alone has been used to characterize membrane binding and describe how these studies yielded novel insight into the molecular events associated with membrane interactions and how they provided a significant impetus to more recent studies that focus on coincident membrane structure changes during binding of peptides and proteins. We then discuss the emerging limitations of not monitoring the effects on membrane structure and how SPR data can be combined with DPI to provide significant new information on how a membrane responds to the binding of peptides and proteins.

Effect of dimerized melittin on gastric cancer cells and antibacterial activity

Melittin is the peptide toxin found in bee venom and is effective against cancer cells. To enhance its activity, a branched dimeric form of melittin was designed. The monomeric form of the peptide was more cytotoxic against gastric cancer cells at low concentrations (1-5 μM) than the dimer form, while the cytotoxic effect was comparable at higher concentrations (10 μM). Confocal microscopy showed that both the monomer and dimer forms of melittin with fluorescent label at the C terminus penetrated the cytoplasm and localized at the cell nucleus and disrupted the cell membrane. The results indicated that both peptides localized in the nucleus and no significant difference in penetration was observed between monomer and dimer of melittin. Although the C and N termini are important for melittin activity, using C terminus for dimerization of the peptide resulted in similar activity for the monomer and dimer against bacteria and gastric cancer cells.

Melittin Constrains the Expression of Identified Key Genes Associated with Bladder Cancer

This work is aimed at investigating the effect of melittin on identified key genes in bladder cancer (BC) and further providing a theoretical basis for BC treatment. GSE35014 downloaded from the Gene Expression Omnibus (GEO) database was used to screen differentially expressed genes (DEGs) in BC cells and control. Results showed that a total of 389 upregulated and 169 downregulated genes were identified. Subsequently, GO analysis, KEGG pathway enrichment analysis, and PPI network analysis were employed to disclose the crucial genes and signaling pathways involved in BC. Fifteen module-related DEGs and their associated signaling pathways were obtained according to the PPI network and modular analyses. Based on the analysis of articles retrieved in the PubMed database, we found that melittin could induce apoptosis and constrain the progression of tumor cells as a result of regulating critical cancer-related signaling pathways, such as PI3K-Akt and TNF signaling pathways. Furthermore, PI3K-Akt and TNF signaling pathways were also found to be associated with module-related DEGs according to biological analyses. At last, qRT-PCR analysis demonstrated that melittin could constrain the expression of module-related DEGs (LPAR1, COL5A1, COL6A2, CXCL1, CXCL2, and CXCL3) associated with PI3K-Akt and TNF signaling pathways in BC cells. Functional assays revealed that melittin could constrain the proliferative and migrated abilities of BC cells. Conjointly, these findings provide a theoretical basis for these six genes as drug-sensitive markers of melittin in BC treatment.

Nuclear Magnetic Resonance-Based Structural Characterization and Backbone Dynamics of Recombinant Bee Venom Melittin

In recent years, there has been a resurgence of interest in melittin and its variants as their therapeutic potential has become increasingly evident. Melittin is a 26-residue peptide and a toxic component of honey bee venom. The versatility of melittin in interacting with various biological substrates, such as membranes, glycosaminoglycans, and a variety of proteins, has inspired a slew of studies that aim to improve our understanding of the structural basis of such interactions. However, these studies have largely focused on melittin solutions at high concentrations (>1 mM), even though melittin is generally effective at lower (micromolar) concentrations. Here we present high-resolution nuclear magnetic resonance studies in the lower-concentration regime using a novel method to produce isotope-labeled (¹⁵N and ¹³C) recombinant melittin. We provide residue-specific structural characterization of melittin in dilute aqueous solution and in 2,2,2-trifluoroethanol/water mixtures, which mimic melittin structure-function and interactions in aqueous and membrane-like environments, respectively. We find that the cis-trans isomerization of Pro14 is key to changes in the secondary structure of melittin. Thus, this study provides residue-specific structural information about melittin in the free state and in a model of the substrate-bound state. These results, taken together with published work from other laboratories, reveal the peptide's structural versatility that resembles that of intrinsically disordered proteins and peptides.

Identification and the molecular mechanism of a novel myosin-derived ACE inhibitory peptide

The objective of this work was to identify a novel ACE inhibitory peptide from myosin using a number of in silico methods.

Effects of chitosan scaffold along with royal jelly or bee venom in regeneration of critical sized radial bone defect in rat

The aim of this study was to compare the efficacy of honey bee venom (BV) and royal jelly (RJ) alongside chitosan scaffold (CS) in improving radius bone defect in rats. A total of 60 full thickness radial bone defects with a length of 5 mm were created in 60 male Wistar rats. Six healthy radial bones (3 rats) were also assigned as normal control for biomechanical studies. The defects were left empty (untreated group) or were filled by the autograft (autograft group), CS (CS group), CS alongside the BV solution (CS-BV group), and CS alongside the RJ solution (CS-RJ group). Healing of the bone defects were evaluated clinically and radiologically on days 0, 28, 42 and 56 after operation while the biomechanical testing and histopathological examination were performed on the 56th day after surgery. The autograft was more radiopaque than the untreated and CS groups at the 28th, 42nd and 56th postoperative days (P<0.05). The CS-BV and CS-RJ groups showed significantly higher radiographic outcomes than the untreated and CS groups at the 56th post-operative day (P<0.05). The density of osseous tissue (DOT) and the osteocytes and osteoblasts count of the CS-RJ and CS-BV groups were significantly higher than the CS and autograft groups (P<0.05). The biomechanical results of the CS-RJ group were significantly superior to the autograft, while the biomechanical properties of CS-BV group were not significantly different with the autograft group (P>0.05). The scaffolds in CS group were observable in the surgical site after 56 days. There was no significant difference in radiographs, DOT, cartilage tissue and fibrous tissue, and also biomechanical performances of the CS-BV and CS-RJ groups at the 42nd and 56th day after surgery. The untreated and CS groups showed weakest biomechanical results among all groups. It could be concluded that both treatment strategies in the CS-BV and CS-RJ groups were appropriate and useful in treating critical bone defects.

Apoptotic Effect of Melittin Purified from Iranian Honey Bee Venom on Human Cervical Cancer HeLa Cell Line

Melittin, an amphipathic 26-residue peptide, is the main component of honey bee venom. Studies have been demonstrated that melittin has an inhibitory effect on proliferation of cancer cells. However, the precise mechanism of action is not completely understood. In the present study we have shown that purified melittin from Iranian honey bee venom shows anti-cancer effects on human cervical cancer cell line through induction of apoptosis. The venom was collected from Iranian honey bee (Apis mellifera meda) and melittin isolated using reversed phase HPLC. Biological activity of melittin was analyzed by hemolytic test on human red blood cells. In order to investigate whether melittin inhibits proliferation of cervical cancer cells, the viability of the melittin treated HeLa cell line was measured via MTT assay. Finally, cell death analysis was performed using Propidum iodide and Annexin V-FITC dual staining. The results showed that the half hemolytic concentration (HD50) induced by mellitin was 0.5 µg/ml in free FBS solution. IC50 obtained after 12 h at 1.8 µg/ml by MTT assay. According to flow cytometric analysis, melittin induced apoptosis at concentrations more than 1 µg/ml. These results suggest that melittin induces apoptotic cell death in cervical cancerous cells as observed by flow cytometric assay. It is concluded that melittin could be regarded as a potential candidate in future studies to discovery of new anticancer agents.

Low virulence potential and in vivo transformation ability in the honey bee venom treated Clinostomum complanatum

The helminth parasites possess great capabilities to adapt themselves within their hosts and also develop strategies to render the commonly used anthelmintics ineffective leading to the development of resistance against these drugs. Besides using anthelmintics the natural products have also been tested for their anti-parasitic effects. Therapeutic efficacy of honey bee venom (HBV) has been tested in various ailments including some protozoal infections but very little is known about its anthelmintic properties. To investigate the anthelmintic effect of HBV the excysted progenetic metacercariae of Clinostomum complanatum, a heamophagic, digenetic trematode with zoonotic potential, infecting a wide variety of hosts, were obtained from Trichogaster fasciatus, a forage fish, which serves as the intermediate host. The metacercarial worms were in vitro incubated in RPMI-1640 medium containing HBV along with the controls which were devoid of HBV for the analysis of worm motility, enzyme activity, polypeptide profile and surface topographical changes. The motility of the worms was significantly reduced in a time dependent manner with an increase in the concentration of HBV. Following incubation of worms the release of cysteine proteases was inhibited in the presence of HBV as revealed by gelatine substrate gel zymography. As well as the polypeptide profile was also significantly influenced, particularly intensity/expression of M_r 19.4 kDa, 24 kDa and 34 kDa was significantly reduced upon HBV treatment. The HBV treatment also inhibited antioxidant enzyme, superoxide dismutase (SOD) and Glutathione-S-transferase (GST) significantly (p < 0.05) in the worms. The scanning electron microscopy of the HBV treated worms revealed tegumental disruptions and erosion of papillae as well as spines showing vacuolation in the tegument. The HBV treated worms also showed a marked decline in the transformation rate when introduced into an experimental host which further reflect the anthelmintic potential of HBV.