Improved antitumor efficacy and reduced toxicity of liposomes containing bufadienolides

Toad venom bufadienolides and bufotoxins: An updated review

Bufadienolides, naturally found in toad venoms having steroid-like structures, reveal antiproliferative effects at low doses. However, their application as anticancer drugs is strongly prevented by their Na+ /K+ -ATPase binding activities. Although several kinds of research were dedicated to moderating their Na+ /K+ -ATPase binding activity, still deeper fundamental knowledge is required to bring these findings into medical practice. In this work, we reviewed data related to anticancer activity of bufadienolides such as bufalin, arenobufagin, bufotalin, gamabufotalin, cinobufotalin, and cinobufagin and their derivatives. Bufotoxins, derivatives of bufadienolides containing polar molecules mainly belonging to argininyl residues, are reviewed as well. The established structures of bufotoxins have been compiled into a one-page figure to review their structures. We also highlighted advances in the structure-modification of the structure of compounds in this class. Drug delivery approaches to target these compounds to tumor cells were discussed in one section. The issues related to extraction, identification, and quantification are separated into another section.

Novel Strategies for Solubility and Bioavailability Enhancement of Bufadienolides

Toad venom contains a large number of bufadienolides, which have a variety of pharmacological activities, including antitumor, cardiovascular, anti-inflammatory, analgesic and immunomodulatory effects. The strong antitumor effect of bufadienolides has attracted considerable attention in recent years, but the clinical application of bufadienolides is limited due to their low solubility and poor bioavailability. In order to overcome these shortcomings, many strategies have been explored, such as structural modification, solid dispersion, cyclodextrin inclusion, microemulsion and nanodrug delivery systems, etc. In this review, we have tried to summarize the pharmacological activities and structure-activity relationship of bufadienolides. Furthermore, the strategies for solubility and bioavailability enhancement of bufadienolides also are discussed. This review can provide a basis for further study on bufadienolides.

Molecular mechanisms of bufadienolides and their novel strategies for cancer treatment

Bufadienolides are cardioactive C24 steroids with an α-pyrone ring at position C17. In the last ten years, accumulating studies have revealed the anticancer activities of bufadienolides and their underlying mechanisms, such as induction of autophagy and apoptosis, cell cycle disruption, inhibition of angiogenesis, epithelial-mesenchymal transition (EMT) and stemness, and multidrug resistance reversal. As Na⁺/K⁺-ATPase inhibitors, bufadienolides have inevitable cardiotoxicity. Short half-lives, poor stability, low plasma concentration and oral bioavailability in vivo are obstacles for their applications as drugs. To improve the drug potency of bufadienolides and reduce their side effects, prodrug strategies and drug delivery systems such as liposomes and nanoparticles have been applied. Therefore, systematic and recapitulated information about the antitumor activity of bufadienolides, with special emphasis on the molecular or cellular mechanisms, prodrug strategies and drug delivery systems, is of high interest. Here, we systematically review the anticancer effects of bufadienolides and the molecular or cellular mechanisms of action. Research advancements regarding bufadienolide prodrugs and their tumor-targeting delivery strategies are critically summarized. This work highlights recent scientific advances regarding bufadienolides as effective anticancer agents from 2011 to 2019, which will help researchers to understand the molecular pathways involving bufadienolides, resulting in a selective and safe new lead compound or therapeutic strategy with improved therapeutic applications of bufadienolides for cancer therapy.

Temperature-sensitive gel-loaded composite nanomedicines for the treatment of cervical cancer by vaginal delivery

In this study, toad venom (TV) and realgar were loaded into a poloxamer 188/407 (F127/F188)-based temperature-sensitive in situ gel (TISG) and encapsulated in solid lipid nanoparticles (TV-SLN) or ground nano-realgar (NR) to improve drug release and reduce local irritation after vaginal administration. The combination of TV-SLN and NR (TV-SLN/NR) greatly enhanced the inhibition of tumor cell proliferation and was most effective at a dose ratio of 2:3 (w/w). After TV-SLN/NR treatment, S and G0/G1 phase arrest were observed in HeLa and SKOV-3 cells and the inhibitory effects on proliferation were stronger than those in the conventional powder group. The gelation temperature of TV-SLN and NR-loaded TISG (TV-SLN/NR-TISG) using the selected formulation was 33 ± 0.91 °C. The cumulative release of the drug increased as the dissolution of gel progressed, showing a linear relationship (r > 0.99). TV-SLN/NR-TISG enabled the sustained release of cargo by adhesion to the vaginal mucosa and showed excellent biocompatibility during continuous administration for 7 days. We specifically demonstrated the effectiveness of the TISG for the vaginal delivery of TV-SLN and NR, supporting its important clinical implications for the treatment of cervical cancer.

Metabolites from Bufo gargarizans (Cantor, 1842): A review of traditional uses, pharmacological activity, toxicity and quality control

ETHNOPHARMACOLOGICAL RELEVANCE

Bufo gargarizans (Cantor, 1842) (BGC), a traditional medicinal animal distributed in many provinces of China, is well known for the pharmaceutical value of Chansu and Chanpi. As traditional Chinese medicines (TCMs), Chansu and Chanpi, with their broad-spectrum of therapeutic applications, have long been applied to detoxification, anti-inflammation, analgesia, etc. OVERARCHING OBJECTIVE: We critically analyzed the current evidence for the traditional uses, chemical profiles, pharmacological activity, toxicity and quality control of BGC (Bufonidae family) to provide a scientific basis for future in-depth studies and perspectives for the discovery of potential drug candidates.

METHODOLOGY

All of the available information on active constituents and TCMs derived from BGC was obtained using the keywords "Bufo gargarizans", "Chansu", "Chanpi", "Huachansu", or "Cinobufacini" through different electronic databases, including PubMed, Web of Science, Chinese National Knowledge Infrastructure (CNKI), the Wanfang Database, and Pharmacopoeia of China. In addition, Chinese medicine books from different times were used to elucidate the traditional uses of BGC. Electronic databases, including the "IUCN Red List of Threatened Species", "American Museum of Natural History" and "AmphibiaWeb Species Lists", were used to validate the scientific name of BGC.

RESULTS

To date, about 118 bufadienolide monomers and 11 indole alkaloids have been identified from BGC in total. The extracts and isolated compounds exhibit a wide range of in vitro and in vivo pharmacological effects. The literature search demonstrated that the ethnomedicinal uses of BGC, such as detoxification, anti-inflammation and the ability to reduce swelling and pain associated with infections, are correlated with its modern pharmacological activities, including antitumor, immunomodulation and attenuation of cancer-derived pain. Bufadienolides and indole alkaloids have been regarded as the main active substances in BGC, among which bufadienolides have significant antitumor activity. Furthermore, the cardiotoxicity of bufadienolides was discussed, and the main molecular mechanism involves in the inhibition of Na⁺/K⁺-ATPase. Besides, with the development of modern analytical techniques, the quality control methods of BGC-derived TCMs are being improved constantly.

CONCLUSIONS

An increasing number of reports suggest that BGC can be regarded as an excellent source for exploring the potential antitumor constituents. However, the future antitumor research of BGC needs to follow the standard pharmacology guidelines, so as to provide comprehensive pharmacological information and aid the reproducibility of the data. Besides, to ensure the efficacy and safety of BGC-derived TCMs, it is vital to construct a comprehensive quality evaluation model on the basis of clarifying pharmacodynamic-related and toxicity-related compositions.

Renal ultrastructural alterations induced by various preparations of mefenamic acid

Mefenamic acid (MFA) treatment is associated with a number of cellular effects that potentiate the incidence of renal toxicity. The aim of this study is to investigate the potential ultrastructural alterations induced by various preparations of MFA (free MFA, MFA-Tween 80 liposomes, and MFA-DDC liposomes) on the renal tissues. Sprague-Dawley rats were subjected to a daily dose of MFA preparations for 28 days. Renal biopsies from all groups of rats under study were processed for transmission electron microscopic examination. The findings revealed that MFA preparations induced various ultrastructural alterations including mitochondrial injury, nuclear and lysosomal alterations, tubular cells steatosis, apoptotic activity, autophagy, and nucleophagy. These alterations were more clear in rats received free MFA, and MFA-Tween 80 liposomes than those received MFA-DDC liposomes. It is concluded that MFA-DDC liposomes are less potential to induce renal damage than free MFA and MFA-Tween 80 liposomes. Thus, MFA-DDC liposomes may offer an advantage of safe drug delivery.

The Development of Toad Toxins as Potential Therapeutic Agents

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.

Quantitative proteomics reveals molecular mechanism of gamabufotalin and its potential inhibition on Hsp90 in lung cancer

Gamabufotalin (CS-6) is a major bufadienolide of Chansu, which shows desirable metabolic stability and less adverse effect in cancer therapy. CS-6 treatment inhibited the proliferation of NSCLC in a nanomolar range. And CS-6 could induce G2/M cell cycle arrest and apoptosis in A549 cells. However, its molecular mechanism in antitumor activity remains poorly understood. We employed a quantitative proteomics approach to identify the potential cellular targets of CS-6, and found 38 possible target-related proteins. Among them, 31 proteins were closely related in the protein-protein interaction network. One of the regulatory nodes in key pathways was occupied by Hsp90. Molecular docking revealed that CS-6 interacted with the ATP-binding sites of Hsp90. In addition, CS-6 inhibited the chaperone function of Hsp90 and reduced expression of Hsp90-dependent client proteins. Moreover, CS-6 markedly down-regulated the protein level of Hsp90 in tumor tissues of the xenograft mice. Taken together, our results suggest that CS-6 might be a novel inhibitor of Hsp90, and the possible network associated with CS-6 target-related proteins was constructed, which provided experimental evidence for the preclinical value of using CS-6 as an effective antitumor agent in treatment of NSCLC.

Bufadienolides of Kalanchoe species: an overview of chemical structure, biological activity and prospects for pharmacological use

Toad venom is regarded as the main source of bufadienolides; however, synthesis of these substances takes also place in a variety of other animal and plant organisms, including ethnomedicinal plants of the Kalanchoe genus. Chemically, bufadienolides are a group of polyhydroxy C-24 steroids and their glycosides, containing a six-membered lactone (α-pyrone) ring at the C-17β position. From the pharmacological point of view, bufadienolides might be a promising group of steroid hormones with cardioactive properties and anticancer activity. Most of the literature concerns bufadienolides of animal origin; however, the medicinal use of these compounds remains limited by their narrow therapeutic index and the risk of development of cardiotoxic effects. On the other hand, plants such as Kalanchoe are also a source of bufadienolides. Kalanchoe pinnata (life plant, air plant, cathedral bells), Kalanchoe daigremontiana (mother of thousands) and other Kalanchoe species are valuable herbs in traditional medicine of Asia and Africa. The present review focuses on the available data on chemical structures of 31 compounds, biological properties and prospects for therapeutic use of bufadienolides from Kalanchoe species. Furthermore, it presents some new investigational trends in research on curative uses of these substances.

Improving In Vivo Efficacy of Bioactive Molecules: An Overview of Potentially Antitumor Phytochemicals and Currently Available Lipid-Based Delivery Systems

Cancer is among the leading causes of morbidity and mortality worldwide. Many of the chemotherapeutic agents used in cancer treatment exhibit cell toxicity and display teratogenic effect on nontumor cells. Therefore, the search for alternative compounds which are effective against tumor cells but reduce toxicity against nontumor ones is of great importance in the progress or development of cancer treatments. In this sense, scientific knowledge about relevant aspects of nutrition intimately involved in the development and progression of cancer progresses rapidly. Phytochemicals, considered as bioactive ingredients present in plant products, have shown promising effects as potential therapeutic/preventive agents on cancer in several in vitro and in vivo assays. However, despite their bioactive properties, phytochemicals are still not commonly used in clinical practice due to several reasons, mainly attributed to their poor bioavailability. In this sense, new formulation strategies are proposed as carriers to improve their bioefficacy, highlighting the use of lipid-based delivery systems. Here, we review the potential antitumoral activity of the bioactive compounds derived from plants and the current studies carried out in animal and human models. Furthermore, their association with lipids as a formulation strategy to enhance their efficacy in vivo is also reported. The development of high effective bioactive supplements for cancer treatment based on the improvement of their bioavailability goes through this association.

Podophyllotoxin-Loaded Nanostructured Lipid Carriers for Skin Targeting: In Vitro and In Vivo Studies

Nanostructured lipid carriers (NLC) exhibit high skin targeting efficiency and good safety. They are promising vehicles for topical drug delivery. This study aims to increase the skin distribution of podophyllotoxin (POD) by incorporating it into NLCs. Two kinds of POD-loaded NLCs (POD-NLCs)—POD-NLC_{formulation 1} and POD-NLC_{formulation 2}—were prepared and characterized. Their skin targeting efficiencies were compared by conducting in vitro and in vivo experiments. Obviously smaller mean particle size was observed for POD-NLC_{formulation 1} (106 nm) than POD-NLC_{formulation 2} (219 nm), whereas relatively low POD loadings (less than 0.5%) were observed for both POD-NLC_{formulation 1} (0.33%) and POD-NLC_{formulation 2} (0.49%). Significantly higher in vitro and in vivo rat skin deposit amounts of POD (p ˂ 0.01) were detected after the topical application of POD-NLC_{formulation 1} compared to POD-NLC_{formulation 2}. To visualize the skin distribution behavior of hydrophobic active pharmaceutical ingredients (APIs) when NLCs were used as carriers, POD was replaced with Nile red (NR—a hydrophobic fluorescent probe), and the distribution behavior of NR-NLC_{formulation 1} and NR-NLC_{formulation 2} in rat skin in vivo was observed using confocal laser scanning microscopy (CLSM). Higher fluorescent intensity was observed in rat skin after the topical application of NR-NLC_{formulation 1} than NR-NLC_{formulation 2}, suggesting that higher skin targeting efficiency might be obtained when NLCs with smaller mean particle size were used as carriers for hydrophobic APIs. This result was in accordance with those of skin distribution evaluation experiments of POD-NLCs. Skin irritation property of POD-NLC_{formulation 1} was investigated and no irritation was observed in intact or damaged rabbit skin, suggesting it is safe for topical use. Our results validated the safety of NLCs when applied topically. More importantly, mean particle size might be an important parameter for formulation optimization when NLCs are used as carriers for hydrophobic APIs for topical application, considering that their loading is relatively low.

Chemical profiling and cytotoxicity assay of bufadienolides in toad venom and toad skin

ETHNOPHARMACOLOGICAL RELEVANCE

Toad venom and toad skin have been widely used for treating various cancers in China. Bufadienolides are regarded as the main anticancer components of toad venom, but the difference on composition and anticancer activities of bufadienolides between toad venom and toad skin remains unclear.

METHODS

Fractions enriched with free and conjugated bufadienolides were prepared from toad venom and toad skin. Bufadienolides in each fraction were comprehensively profiled by using a versatile UHPLC-TOF-MS method. Relative contents of major bufadienolides were determined by using three bufogenins and one bufotoxin as marker compounds with validated UHPLC-TOF-MS method. Furthermore, cytotoxicity of the fractions was examined by MTT assay.

RESULTS

Two fractions, i.e., bufogenin and bufotoxin fractions (TV-F and TV-C) were isolated from toad venom, and one bufotoxin fraction (TS-C) was isolated from toad skin. Totally 56 bufadienolides in these three fractions were identified, and 29 were quantified or semi-quantified. Bufotoxins were identified in both toad venom and toad skin, whereas bufogenins exist only in toad venom. Bufalin-3-conjugated bufotoxins are major components in toad venom, whereas cinobufotalin and cinobufagin-3-conjugated bufotoxins are main bufotoxins in toad skin. MTT assay revealed potent cytotoxicity of all the fractions in an order of TV-F>TV-C>TS-C.

CONCLUSIONS

Our study represents the most comprehensive investigation on the chemical profiles of toad venom and toad skin from both qualitative and quantitative aspects. Eight bufotoxins were identified in toad skin responsible for the cytotoxicity for the first time. Our research provides valuable chemical evidence for the appropriate processing method, quality control and rational exploration of toad skin and toad venom for the development of anticancer medicines.

The construction of puerarin nanocrystals and its pharmacokinetic and in vivo-in vitro correlation (IVIVC) studies on beagle dog

Puerarin is widely used in clinics in China as a therapeutic agent for cardiovascular diseases by intravenous administration. Adverse drug reactions caused by cosolvents often increase the patients' treatment burden (high drug costs and low compliance). The development of oral formulation is urgently needed and nanocrystal technique has become a preferred way to develop oral dosage form, nowadays. In this study, high pressure homogenization (HPH) was employed to prepare puerarin nanocrystals by employing SDS as the stabilizer, and redispersibility of the nanocrystals powder was also studied. The nanocrystals prepared was characterized using DLS, DSC, XRD and SEM. A preferred in vivo-in vitro correlation was also established in this study. Pharmacokinetic studies on beagle dog showed that comparing to raw puerarin powder, both of the Cmax and AUC of puerarin nanocrystals were enhanced. From the above results, we can conclude that nanocrystal technique is an efficient technology to improve the oral bioavailability of puerarin.

Nanoformulations for therapy of pancreatic and liver cancers

Pancreatic and liver cancers often have poor prognoses. Clinically, pancreatic and liver cancer requires early diagnosis, and surgery is often associated with tumor recurrence. Currently, chemotherapies are limited in their ability to accurately target the tumors, and are associated with significant toxicity in patients. Targeting of chemotherapy can be improved by encapsulation in nanocarriers. A variety of preclinical studies indicate relatively superior therapeutic outcomes compared with drug alone therapy. Targeted nanoparticle imaging agents may also additionally facilitate better diagnosis and improve patient outcomes. This review discusses the nanoformulations that are under investigation (mainly preclinical studies, but also with some current clinical trial examples) against pancreatic and liver cancers, understands the challenges and provides future perspectives.

Post-insertion of poloxamer 188 strengthened liposomal membrane and reduced drug irritancy and in vivo precipitation, superior to PEGylation

The ultimate aim of this study was to develop asulacrine (ASL)-loaded long-circulating liposomes to prevent phlebitis during intravenous (i.v.) infusion for chemotherapy. Poly(ethylene)glycol (PEG) and poloxamer 188-modified liposomes (ASL-PEGL and ASL-P188L) were developed, and ASL was loaded using a remote loading method facilitated with a low concentration of sulfobutyl ether-β-cyclodextrin as a drug solubilizer. The liposomes were characterized in terms of morphology, size, release properties and stability. Pharmacokinetics and venous tissue tolerance of the formulations were simultaneously studied in rabbits following one-hour i.v. infusion via the ear vein. The irritancy was assessed using a rat paw-lift/lick model after subplantar injections. High drug loading 9.0% w/w was achieved with no drug leakage found from ASL-PEGL or ASL-P188L suspended in a 5% glucose solution at 30days. However, a rapid release (leakage) from ASL-PEGL was observed when PBS was used as release medium, partially related to the use of cyclodextrin in drug loading. Post-insertion of poloxamer 188 to the liposomes appeared to be able to restore the drug retention possibly by increasing the packing density of phospholipids in the membrane. In rabbits (n=5), ASL-P188L had a prolonged half-life with no drug precipitation or inflammation in the rabbit ear vein in contrast to ASL solution. Following subplantar (footpad) injections in rats ASL solution induced paw-lick/lift responses in all rats whereas ASL-P188L caused no response (n=8). PEGylation showed less benefit possibly due to the drug 'leakage'. In conclusion, drug precipitation in the vein and the drug mild irritancy may both contribute to the occurrence of phlebitis caused by the ASL solution, and could both be prevented by encapsulation of the drug in liposomes. Poloxamer 188 appeared to be able to 'seal' the liposomal membrane and enhance drug retention. The study also highlighted the importance of bio-relevant in vitro release study in formulation screening.

CLC-3 channels in cancer (review)

Ion channels are involved in regulating cell proliferation and apoptosis (programed cell death). Since increased cellular proliferation and inhibition of apoptosis are characteristic features of tumorigenesis, targeting ion channels is a promising strategy for treating cancer. CLC-3 is a member of the voltage-gated chloride channel superfamily and is expressed in many cancer cells. In the plasma membrane, CLC-3 functions as a chloride channel and is associated with cell proliferation and apoptosis. CLC-3 is also located in intracellular compartments, contributing to their acidity, which increases sequestration of drugs and leads to chemotherapy drug resistance. In this review, we summarize the recent findings concerning the involvement of CLC-3 in cancer and explore its potential in cancer therapy.

Strategies to maximize liposomal drug loading for a poorly water-soluble anticancer drug

PURPOSE

To develop a liposomal system with high drug loading (DL) for intravenous (i.v.) delivery of a poorly water-soluble basic drug, asulacrine (ASL).

METHODS

A thin-film hydration and extrusion method was used to fabricate the PEGylated liposomal membranes followed by a freeze and thaw process. A novel active drug loading method was developed using ammonium sulphate gradient as an influx driving force of ASL solubilized with sulfobutyl ether-β-cyclodextrin (SBE-β-CD). DL was maximized by optimizing liposomal preparation and loading conditions. Pharmacokinetics was evaluated following i.v. infusion in rabbits.

RESULTS

Freeze-thaw resulted in unilamellar liposome formation (180 nm) free of micelles. Higher DL was obtained when dialysis was used to remove the untrapped ammonium sulphate compared to ultracentrifuge. The pH and SBE-β-CD level in the loading solution played key roles in enhancing DL. High DL ASL-liposomes (8.9%w/w, drug-to-lipid mole ratio 26%) were obtained with some drug "bundles" in the liposomal cores and were stable in a 5% glucose solution for >80 days with minimal leakage (<2%). Surprisingly, following administration of ASL-liposomes prepared with or without SBE-β-CD, the half-lives were similar to the drug solution despite an increased area under the curve, indicating drug leakage from the carriers.

CONCLUSIONS

High liposomal DL was achieved with multiple strategies for a poorly-water soluble weak base. However, the liposomal permeability needed to be tailored to improve drug retention.

Physicochemical characterization of asulacrine towards the development of an anticancer liposomal formulation via active drug loading: stability, solubility, lipophilicity and ionization

To facilitate the development of a liposomal formulation for cancer therapy, the physicochemical properties of asulacrine (ASL), an anticancer drug candidate, were characterized. Nano-liposomes were prepared by thin-film hydration in conjugation with active drug loading using ammonium sulphate and post-insertion with Poloxamer 188. A stability-indicating HPLC assay with diode array detection was developed for the determination of ASL concentrations. The U-shaped pH-solubility profile in aqueous solutions, with a lowest solubility at pH 7.4 (0.843 μg/mL), indicated that ASL is an ampholyte, and dilution or neutralization of acidic drug solutions used in clinical trials with physiological fluids may cause drug precipitation. The basic pKa value measured by absorbance spectroscopy was 6.72. The logD value at pH 3.8 was 1.15 which increased to 3.24 as pH increased to 7.4. ASL was found to be the most stable in acidic conditions and degraded most rapidly in alkaline conditions. An extra-liposomal pH of 5.6 during drug loading was found to be optimal to achieve the highest drug loading (DL) of 4.76% and entrapment efficiency (EE) of 99.9%. At this pH, >90% of ASL was ionized conferring high drug solubility (1mg/mL) and acted as a reservoir of unionized ASL to be transported into liposomal cores. As a suspension the optimized liposomes showed great physicochemical stability for five months at 4°C. In summary, the obtained physicochemical parameters provided insightful information useful to maximise DL into the liposomes, and explain a tendency of drug precipitation of pH-solubilized formulations following intravenous infusion.

Toad glandular secretions and skin extractions as anti-inflammatory and anticancer agents

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.

Bufalin-loaded mPEG-PLGA-PLL-cRGD nanoparticles: preparation, cellular uptake, tissue distribution, and anticancer activity

BACKGROUND

Recent studies have shown that bufalin has a good antitumor effect but has high toxicity, poor water solubility, a short half-life, a narrow therapeutic window, and a toxic dose that is close to the therapeutic dose, which all limit its clinical application. This study aimed to determine the targeting efficacy of nanoparticles (NPs) made of methoxy polyethylene glycol (mPEG), polylactic-co-glycolic acid (PLGA), poly-L-lysine (PLL), and cyclic arginine-glycine-aspartic acid (cRGD) loaded with bufalin, ie, bufalin-loaded mPEG-PLGA-PLL-cRGD nanoparticles (BNPs), in SW620 colon cancer-bearing mice.

METHODS

BNPs showed uniform size. The size, shape, zeta potential, drug loading, encapsulation efficiency, and release of these nanoparticles were studied in vitro. The tumor targeting, cellular uptake, and growth-inhibitory effect of BNPs in vivo were tested.

RESULTS

BNPs were of uniform size with an average particle size of 164 ± 84 nm and zeta potential of 2.77 mV. The encapsulation efficiency was 81.7% ± 0.89%, and the drug load was 3.92% ± 0.16%. The results of in vitro cytotoxicity studies showed that although the blank NPs were nontoxic, they enhanced the cytotoxicity of bufalin in BNPs. Drug release experiments showed that the release of the drug was prolonged and sustained. The results of confocal laser scanning microscopy indicated that BNPs could effectively bind to human umbilical vein endothelial cells. In the SW620 xenograft mice model, the BNPs could effectively target the tumor in vivo. The BNPs were significantly more effective than other NPs in preventing tumor growth.

CONCLUSION

BNPs had even size distribution, were stable, and had a slow-releasing and tumor-targeting effect. BNPs significantly inhibited colon cancer growth in vitro and in vivo. As a novel drug carrier system, BNPs are a potentially promising targeting treatment for colon cancer.