Antiangiogenic activity of PLGA-Lupeol implants for potential intravitreal applications

Exploring the therapeutic potential of lupeol: A review of its mechanisms, clinical applications, and advances in bioavailability enhancement

Lupeol, a naturally occurring triterpenoid, has garnered significant attention for its diverse range of biological activities and potential therapeutic applications. This comprehensive review delves into the various aspects of lupeol, including its sources, extraction methods, chemical characteristics, pharmacokinetics, safety evaluation, mechanisms of action, and applications in disease treatment. We highlight the compound's unique carbon skeleton and its role in inflammation regulation, antioxidant activity, and broad-spectrum antimicrobial effects. The review also underscores lupeol's potential in cancer therapy, cardiovascular protection, metabolic disease management, and wound healing. Furthermore, we discuss the challenges and future perspectives of lupeol's clinical application, emphasizing the need for further research to improve its bioavailability and explore its full therapeutic potential. The review concludes by recognizing the significance of lupeol in drug development and healthcare, with expectations for future breakthroughs in medical applications.

Lupeol: A dietary and medicinal triterpene with therapeutic potential

Lupeol, a triterpene derived from various plants, has emerged as a potent dietary supplement with extensive therapeutic potential. This review offers a comprehensive examination of lupeol's applications across diverse health conditions. By meticulously analyzing current scientific literature, we have synthesized findings that underscore lupeol's impact on cancer, diabetes, gastrointestinal disorders, neurological diseases, dermatological conditions, nephrological issues, and cardiovascular health. The review delves into molecular studies that reveal lupeol's ability to modulate disease pathways and alleviate symptoms, positioning it as a promising therapeutic agent. Moreover, we discuss the potential role of lupeol in clinical practice and public health strategies, emphasizing its substantial benefits as a natural compound. This thorough analysis serves as a critical resource for researchers, providing insights into the multifaceted therapeutic properties of lupeol and its potential to significantly enhance health outcomes.

Effects of natural products on angiogenesis in melanoma

Melanoma is the most aggressive form of skin cancer and originates from genetic mutations in melanocytes. The disease is multifactorial, but its main cause is overexposure to UV radiation. Currently, available chemotherapy expresses little to no results, which may justify the extensive use of natural products to treat this cancer. In this study, we reviewed the inhibition of melanoma angiogenesis by natural products and its potential mechanisms using literature from PubMed, EMBASE, Web of Science, Ovid, ScienceDirect and China National Knowledge Infrastructure databases. According to summarizes 27 natural products including alkaloids, polyphenols, terpenoids, flavonoids, and steroids that effectively inhibit angiogenesis in melanoma. In addition to these there are 15 crude extracts that can be used as promising agents to inhibit angiogenesis, but their core components still deserve further investigation. There are current studies on melanoma angiogenesis involving oxidative stress, immune-inflammatory response, cell proliferation and migration and capillary formation. The above natural products can be involved in melanoma angiogenesis through core targets such as VE-cadherin, COX-2, iNOS, VEGF, bFGF, FGF2,MMP2,MMP9,IL-1β,IL-6 play a role in inhibiting melanoma angiogenesis. Effective excavation of natural products can not only clarify the mechanism of drug action and key targets, but also help to promote the preclinical research of natural products for melanoma treatment and further promote the development of new clinical drugs, which will bring the gospel to the vast number of patients who are deeply afflicted by melanoma.

In Situ Formation of Injectable Gelatin Methacryloyl (GelMA) Hydrogels for Effective Intraocular Delivery of Triamcinolone Acetonide

A novel drug delivery system designed for intraocular injection, gelatin methacryloyl (GelMA), has attracted much attention due to its sustained-release character and low cytotoxicity. We aimed to explore the sustained drug effect of GelMA hydrogels coupled with triamcinolone acetonide (TA) after injection into the vitreous cavity. The GelMA hydrogel formulations were characterized using scanning electron microscopy, swelling measurements, biodegradation, and release studies. The biological safety effect of GelMA on human retinal pigment epithelial cells and retinal conditions was verified by in vitro and in vivo experiments. The hydrogel exhibited a low swelling ratio, resistance to enzymatic degradation, and excellent biocompatibility. The swelling properties and in vitro biodegradation characteristics were related to the gel concentration. Rapid gel formation was observed after injection, and the in vitro release study confirmed that TA-hydrogels have slower and more prolonged release kinetics than TA suspensions. In vivo fundus imaging, optical coherence tomography measurements of retinal and choroid thickness, and immunohistochemistry did not reveal any apparent abnormalities of retinal or anterior chamber angle, and ERG indicated that the hydrogel had no impact on retinal function. The GelMA hydrogel implantable intraocular device exhibited an extended duration, in situ polymerization, and support cell viability, making it an attractive, safe, and well-controlled platform for treating the posterior segment diseases of the eye.

Molecular pharmacology and therapeutic advances of the pentacyclic triterpene lupeol

BACKGROUND

Plant triterpenoids are major sources of nutraceuticals that provide many health benefits to humans. Lupeol is one of the pentacyclic dietary triterpenoids commonly found in many fruits and vegetables, which is highly investigated for its pharmacological effect and benefit to human health.

PURPOSE

This systematic review critically discussed the potential pharmacological benefits of lupeol and its derivatives as evidenced by various cellular and animal model studies. To gain insight into the pharmacological effects of lupeol, the network pharmacological approach is applied. Pharmacokinetics and recent developments in nanotechnology-based approaches to targeted delivery of lupeol along with its safety use are also discussed.

METHODS

This study is dependent on the systematic and non-exhaustive literature survey for related research articles, papers, and books on the chemistry, pharmacological benefits, pharmacokinetics, and safety of lupeol published between 2011 and 2021. For online materials, the popular academic search engines viz. Google Scholar, PubMed, Science Direct, Scopus, ResearchGate, Springer, as well as official websites were explored with selected keywords.

RESULTS

Lupeol has shown promising benefits in the management of cancer and many other human diseases such as diabetes, obesity, cardiovascular diseases, kidney and liver problems, skin diseases, and neurological disorders. The pharmacological effects of lupeol primarily rely on its capacity to revitalize the cellular antioxidant, anti-inflammatory and anti-apoptotic mechanisms. Network pharmacological approach revealed some prospective molecular targets and pathways and presented some significant information that could help explain the pharmacological effects of lupeol and its derivatives. Despite significant progress in molecular pharmacology, the clinical application of lupeol is limited due to poor bioavailability and insufficient knowledge on its mode of action. Structural modification and nanotechnology-guided targeted delivery of lupeol improve the bioavailability and bioactivity of lupeol.

CONCLUSION

The pentacyclic triterpene lupeol possesses numerous human health-benefiting properties. This review updates current knowledge and critically discusses the pharmacological effects and potential applications of lupeol and its derivatives in human health and diseases. Future studies are needed to evaluate the efficacies of lupeol and its derivatives in the management and pathobiology of human diseases.

Microvascular Experimentation in the Chick Chorioallantoic Membrane as a Model for Screening Angiogenic Agents including from Gene-Modified Cells

The chick chorioallantoic membrane (CAM) assay model of angiogenesis has been highlighted as a relatively quick, low cost and effective model for the study of pro-angiogenic and anti-angiogenic factors. The chick CAM is a highly vascularised extraembryonic membrane which functions for gas exchange, nutrient exchange and waste removal for the growing chick embryo. It is beneficial as it can function as a treatment screening tool, which bridges the gap between cell based in vitro studies and in vivo animal experimentation. In this review, we explore the benefits and drawbacks of the CAM assay to study microcirculation, by the investigation of each distinct stage of the CAM assay procedure, including cultivation techniques, treatment applications and methods of determining an angiogenic response using this assay. We detail the angiogenic effect of treatments, including drugs, metabolites, genes and cells used in conjunction with the CAM assay, while also highlighting the testing of genetically modified cells. We also present a detailed exploration of the advantages and limitations of different CAM analysis techniques, including visual assessment, histological and molecular analysis along with vascular casting methods and live blood flow observations.

Intravitreal lupeol: A new potential therapeutic strategy for noninfectious uveitis

Lupeol is a pentacyclic triterpene with known anti-inflammatory effects. However, its role in the treatment of noninfectious uveitis has not been explored. This work investigated anti-inflammatory activity of lupeol in ocular tissues with in vitro and in vivo models. First, we evaluated the effect of lupeol (100 µM) on inflammatory response induced by lipopolysaccharide (LPS) in retinal pigment epithelium cells (ARPE-19) by measuring levels of released interleukins (IL-6 and IL-8). Then, we investigated the anti-inflammatory action of intravitreal lupeol in a rodent model of panuveitis induced by Mycobacterium bovis Calmette-Guérin Bacillus (BCG). Rats were submitted to electroretinography and clinical analyses on days 3, 7, and 15 after uveitis induction. In addition, histopathological analysis, and indirect quantification of myeloperoxidase (MPO) and N-acetylglucosaminidase (NAG) in the posterior segment were performed. Treatment with lupeol (100 µM) significantly decreased IL-6 and IL-8 levels in comparison to untreated LPS-activated ARPE-19 cells. This reduction was similar to that detected in ARPE-19 cells treated with dexamethasone. The results of the in vivo assay demonstrated that intravitreal lupeol is able to modulate inflammation in the anterior and posterior segment of the rat eyes, indicating that it should be further investigated as a novel potential candidate for management of uveitis.

The chick embryo chorioallantoic membrane model: a research approach for ex vivo and in vivo experiments

BACKGROUND

The chick chorioallantoic membrane (CAM) model has attracted a great deal of interest in pharmaceutical and biological research as an alternative or complementary in vivo assay to animal models. Traditionally, CAM assay has been widely used to perform some toxicological studies, specifically to evaluate the skin, ocular and embryo toxicity of new drugs and formulations, and perform angiogenesis studies. Due to the possibility to generate the tumors onto the CAM, this model has also become an excellent strategy to evaluate the metastatic potential of different tumours and test the efficacy of novel anticancer therapies in vivo. Moreover, in the recent years, its use has considerably grown in other research areas, including the evaluation of new anti-infective agents, the development of biodistribution studies and tissue engineering research.

OBJECTIVES

This manuscript provides a critical overview of the use of CAM model in pharmaceutical and biological research, especially to test the toxicity of new drugs and formulations and the biodistribution and the efficacy of novel anticancer and anti-infective therapies, analyzing its advantages and disadvantages compared to animal models.

CONCLUSION

The chick chorioallantoic membrane model shows great utility in several research areas, such as cancer, toxicology, biodistribution studies and anti-infective therapies. In fact, it has become an intermediate stage between in vitro experiments and animal studies, and, in the case of toxicological studies (skin and ocular toxicity), has even replaced the animal models.

Anti-angiogenic activity and safety of intraocular application of triterpenes

PURPOSE

Assessment of the anti-angiogenic activity and the safety of ophthalmic use of four pentacyclic triterpenes (friedelin, friedelinol, lupenone, and lupeol).

METHODS

Triterpenes cytotoxicity (5-640 µmol L^-1) was examined in ARPE-19 cells by sulforhodamine B colorimetric method, and the anti-angiogenic activity (50-1000 µmol L^-1) was evaluated in the chorioallantoic membrane model. Full-field electroretinography and histological analysis were performed to evaluate intraocular effects of these four triterpenes (at 100 or 500 μmol L^-1) in eyes of Wistar rats, for 15 days.

RESULTS

In the cytotoxicity assay, friedelin and friedelinol were not able to drastically reduce cell growth. A dose-dependent response was observed in groups exposed to lupeol or lupenone. During the chorioallantoic membrane assay, friedelinol at 500 μmol L^-1 reduced the vascularity in 26%; lupeol and lupenone showed promising anti-angiogenic activity, reducing three parameters: vascularized area (> 30%), number of junctions (> 20%), and vessel length (> 15%). According to the electroretinographic and histologic findings, triterpenes at 100 µmol L^-1 or lupenone at 500 µmol L^-1 did not induce any transient or permanent disturbance in retinal structure or functioning.

CONCLUSIONS

Triterpenes at 100 µmol L^-1 or lupenone at 500 µmol L^-1 were considered safe for potential ophthalmic use.

Rosmarinic Acid Intravitreal Implants: A New Therapeutic Approach for Ocular Neovascularization

Rosmarinic acid, a plant-derived compound with antiangiogenic activity, can be applied for the treatment of ocular diseases related to neovascularization, such as diabetic retinopathy, macular edema, and age-related macular degeneration. These diseases represent the leading causes of blindness worldwide if they are not properly treated. Intravitreal devices allow for localized drug delivery to the posterior segment, increasing the drug bioavailability and promoting extended release, thus, reducing side effects and enhancing the patient's compliance to the treatment. In this work, rosmarinic acid-loaded poly lactic-co-glycolic acid intraocular implants were developed with a view for the treatment of ocular neovascularization. Physical-chemical, biocompatibility, and safety studies of the implants were carried out in vitro and in vivo as well as an evaluation of the antiangiogenic activity in a chorioallantoic membrane assay. Data obtained showed that rosmarinic acid released from the implants was quantified in the vitreous for 6 weeks, while when it was in the solution formulation, after 24 h, no drug was found in the vitreous. The delivery device did not show any sign of toxicity after clinical evaluation and in electroretinographic findings. Histological analysis showed normal eye tissue. Rosmarinic acid released from implants reduced 30% of new vessel's formation. The intravitreal implant successfully allowed for the prolonged release of rosmarinic acid, was safe to rabbits eyes, and demonstrated activity in vessel reduction, thus demonstrating potential in preventing neovascularization in ophthalmic diseases.

Novel hybrid lipid nanocapsules loaded with a therapeutic monoclonal antibody - Bevacizumab - and Triamcinolone acetonide for combined therapy in neovascular ocular pathologies

The aim of this study was to design and develop a novel hybrid formulation based on lipid nanocapsules containing bevacizumab (BVZ), an effective therapeutic antibody, on the surface and triamcinolone acetonide (TA) in the inner core (BVZ-TA-LNC) intended to improve ocular therapy. Hence, a phase inversion-insertion one step method was developed to drug loading and surface modification of lipid nanocapsules by post-insertion of a bifunctional polymer, followed by antibody coupling using "click" chemistry. The covalent bond and antibody capacity binding to its specific antigen were confirmed by thermal analysis and immunoassay, respectively. BVZ-TA-LNC presented nanometric size (102 nm), negative surface potential (-19 mV) and exhibiting 56% of TA in the lipid core. BVZ-TA-LNC tended to prevent the endothelial cell migration and significantly prevented the capillary formation induced by the vascular endothelium growth factor (VEGF). The novel hybrid system allowed the co-loading of two different therapeutic molecules and may be promising to improve the therapy of eye disorders that occur with inflammation and/or neovascularization.

Bevacizumab-Conjugated Quantum Dots: In Vitro Antiangiogenic Potential and Biosafety in Rat Retina

Purpose: Disturbances that affect the inside of the eyeball tend to be highly harmful since they compromise the homeostasis of this organ. Alongside this, the eyeball has several anatomical barriers that prevent the entry of substances. This way, diseases that affect the retina are among those that present greater difficulty in the treatment. In many cases, abnormal proliferation of blood vessels (neovascularization) occurs from the lower layers of the retina. This process damages its structure physiologically and anatomically, causing the rapid and irreversible loss of visual capacity. This work aims to develop nanosuspensions of quantum dots (QDs) conjugated to bevacizumab. Methods: Two types of QDs were produced by aqueous route, stabilized with chitosan conjugated to bevacizumab. The antiangiogenic activity was evaluated in the chorioallantoic membrane model, in which results indicated discrete activity at the doses tested. Samples were assessed for their biosafety in animals, after intravitreal administration, by means of electroretinography (ERG), intraocular pressure (IOP) measurement, histological, morphometric, and immunohistochemical evaluation. Results: No significant alterations were detected in ERG that suggests damage to retinal function by the samples. No significant changes in IOP were also detected. The histological sections did not show signs of acute inflammation, although there was evidence of late retinal damage. The immunohistochemical analysis did not detect any apoptotic bodies. Conclusion: Preliminary results suggest that QDs present potential applicability in ocular therapy, and it is necessary to better characterize their in vivo behavior and to optimize their dosage.

Chemosensitization of Therapy Resistant Tumors: Targeting Multiple Cell Signaling Pathways by Lupeol, A Pentacyclic Triterpene

Background:

The resistance of cancer cells to different therapies is one of the major stumbling blocks for successful cancer treatment. Various natural and pharmaceuticals drugs are unable to control drug-resistance cancer cell's growth. Also, chemotherapy and radiotherapy have several side effects and cannot apply to the patient in excess. In this context, chemosensitization to the therapy-resistant cells by non-toxic phytochemicals could be an excellent alternative to combat therapy-resistant cancers.

Objective:

To review the currently available literature on chemosensitization of therapy resistance cancers by Lupeol for clinically approved drugs through targeting different cell signaling pathways.

Methods:

We reviewed relevant published articles in PubMed and other search engines from 1999 to 2019 to write this manuscript. The key words used for the search were “Lupeol and Cancer”, “Lupeol and Chemosensitization”, “Lupeol and Cell Signaling Pathways”, “Cancer Stem Cells and Lupeol” etc. The published results on the chemosensitization of Lupeol were compared and discussed.

Results:

Lupeol chemosensitizes drug-resistant cancer cells for clinically approved drugs. Lupeol alone or in combination with approved drugs inhibits inflammation in different cancer cells through modulation of expression of IL-6, TNF-α, and IFN-γ. Lupeol, through altering the expression levels of BCL-2, BAX, Survivin, FAS, Caspases, and PI3K-AKT-mTOR signaling pathway, significantly induce cell deaths among therapy-resistant cells. Lupeol also modulates the molecules involved in cell cycle regulation such as Cyclins, CDKs, P53, P21, and PCNA in different cancer types.

Conclusion:

Lupeol chemosensitizes the therapy-resistant cancer cells for the treatment of various clinically approved drugs via modulating different signaling pathways responsible for chemoresistance cancer. Thus, Lupeol might be used as an adjuvant molecule along with clinically approved drugs to reduce the toxicity and increase the effectiveness.

Recent advances in intraocular sustained-release drug delivery devices

Topical eye-drop administration and intravitreal injections are the current standard for ocular drug delivery. However, patient adherence to the drug regimen and insufficient administration frequency are well-documented challenges to this field. In this review, we describe recent advances in intraocular implants designed to deliver therapeutics for months to years, to obviate the issues of patient adherence. We highlight recent advances in monolithic ocular implants in the literature, the commercialization pipeline, and approved for the market. We also describe design considerations based on material selection, active pharmaceutical ingredient, and implantation site.