Potential applications of antofine and its synthetic derivatives in cancer therapy: structural and molecular insights.

Cancer is a major global health challenge, being the second leading cause of morbidity and mortality after cardiovascular disease. The growing economic burden and profound psychosocial impact on patients and their families make it urgent to find innovative and effective anticancer solutions. For this reason, interest in using natural compounds to develop new cancer treatments has grown. In this respect, antofine, an alkaloid class found in Apocynaceae, Lauraceae, and Moraceae family plants, exhibits promising biological properties, including anti-inflammatory, anticancer, antiviral, and antifungal activities. Several molecular mechanisms have been identified underlying antofine anti-cancerous effects, including the inhibition of nuclear factor κB (NF-κB) and AKT/mTOR signaling pathways, epigenetic inhibition of protein synthesis, ribosomal targeting, induction of apoptosis, inhibition of DNA synthesis, and cell cycle arrest. This study discusses the molecular structure, sources, photochemistry, and anticancer properties of antofine in relation to its structure-activity relationship and molecular targets. Then, examine in vitro and in vivo studies and analyze the mechanisms of action underpinning antofine efficacy against cancer cells. This review also discusses multidrug resistance in human cancer and the potential of antofine in this context. Safety and toxicity concerns are also addressed as well as current challenges in antofine research, including the need for clinical trials and bioavailability optimization. This review aims to provide comprehensive information for more effective natural compound-based cancer treatments.

The Effects of Antofine on the Morphological and Physiological Characteristics of Phytophthora capsici.

Phytophthora capsici is an important plant pathogenic oomycete that causes great losses to vegetable production around the world. Antofine is an important alkaloid isolated from Cynanchum komarovii Al. Iljinski and exhibits significant antifungal activity. In this study, the effect of antofine on the mycelial growth, morphology, and physiological characteristics of P. capsici was investigated using colorimetry. Meanwhile, the activity of mitochondrial respiratory chain complexes of P. capsici was evaluated following treatment with a 30% effective concentration (EC30), as well as EC50 and EC70, of antofine for 0, 12, 24, and 48 h. The results showed that antofine had a significant inhibitory effect against P. capsici, with an EC50 of 5.0795 µg/mL. After treatment with antofine at EC50 and EC70, the mycelia were rough, less full, and had obvious depression; they had an irregular protrusion structure; and they had serious wrinkles. In P. capsici, oxalic acid and exopolysaccharide contents decreased significantly, while cell membrane permeability and glycerol content increased when treated with antofine. Reactive oxygen species (ROS) entered a burst state in P. capsici after incubation with antofine for 3 h, and fluorescence intensity was 2.43 times higher than that of the control. The activities of the mitochondrial respiratory chain complex II, III, I + III, II + III, V, and citrate synthase in P. capsici were significantly inhibited following treatment with antofine (EC50 and EC70) for 48 h compared to the control. This study revealed that antofine is likely to affect the pathways related to the energy metabolism of P. capsici and thus affect the activity of respiratory chain complexes. These results increase our understanding of the action mechanism of antofine against P. capsici.

Antofine Triggers the Resistance Against Penicillium italicum in Ponkan Fruit by Driving AsA-GSH Cycle and ROS-Scavenging System.

Postharvest fungal infection can accelerate the quality deterioration of Ponkan fruit and reduce its commodity value. Penicillium italicum is the causal pathogen of blue mold in harvested citrus fruits, not only causing huge fungal decay but also leading to quality deterioration. In our preliminary study, antofine (ATF) was found to have a great potential for significant in vitro suppression of P. italicum growth. However, the regulatory mechanism underpinning ATF-triggered resistance against P. italicum in citrus fruit remains unclear. Here, the protective effects of ATF treatment on blue mold development in harvested Ponkan fruit involving the enhancement of ROS-scavenging system were investigated. Results showed that ATF treatment delayed blue mold development and peel firmness loss. Moreover, the increase of electrolyte leakage, O2 •- production, and malonyldialdehyde accumulation was significantly inhibited by ATF treatment. The ATF-treated Ponkan fruit maintained an elevated antioxidant capacity, as evidenced by inducted the increase in glutathione (GSH) content, delayed the declines of ascorbic acid (AsA) content and GSH/oxidized GSH ratio, and enhanced the activities of superoxide dismutase, catalase, peroxidase, and six key AsA-GSH cycle-related enzymes, along with their encoding gene expressions, thereby maintaining ROS homeostasis and reducing postharvest blue mold in harvested Ponkan fruit. Collectively, the current study revealed a control mechanism based on ATF-triggered resistance and maintenance of a higher redox state by driving AsA-GSH cycle and ROS-scavenging system in P. italicum-infected Ponkan fruit.

Design, Synthesis and In-Vitro Biological Evaluation of Antofine and Tylophorine Prodrugs as Hypoxia-Targeted Anticancer Agents.

Phenanthroindolizidines, such as antofine and tylophorine, are a family of natural alkaloids isolated from different species of Asclepiadaceas. They are characterized by interesting biological activities, such as pronounced cytotoxicity against different human cancerous cell lines, including multidrug-resistant examples. Nonetheless, these derivatives are associated with severe neurotoxicity and loss of in vivo activity due to the highly lipophilic nature of the alkaloids. Here, we describe the development of highly polar prodrugs of antofine and tylophorine as hypoxia-targeted prodrugs. The developed quaternary ammonium salts of phenanthroindolizidines showed high chemical and metabolic stability and are predicted to have no penetration through the blood-brain barrier. The designed prodrugs displayed decreased cytotoxicity when tested under normoxic conditions. However, their cytotoxic activity considerably increased when tested under hypoxic conditions.

Phytochemical and antitumor studies on Cynanchum mongolicum (Maxim.) Kom.

A chemical investigation of Cynanchum mongolicum (Maxim.) Kom. identified 8 compounds. On the basis of spectroscopic data, they were determined to be 3 alkaloids and 5 sinapoyl esters, among which were two previously undescribed compounds (1 and 2). The inhibitory effects of the isolated compounds against four human tumor cell lines were evaluated in vitro by MTT assays, which revealed moderate inhibitory effects with IC50 values < 50 mM, in particularly, three antofine analogues have showed significant antitumor activities with IC50 values < 0.1 mM, which was obviously better than the 5-fluorouracil and potential to be used as cancer drugs.

Boronic Analogues of (R)-6-O-Desmethylantofine as Anticancer Agents.

Phenanthroindolizidines are naturally occurring alkaloids mainly isolated from different species of Asclepiadaceae. These alkaloids are characterized by an excellent anticancer activity against a very wide range of cancerous cell lines including those who are multi drug resistant. Nevertheless, phenanthroindolizidines are associated with sever neurotoxicity that prevented any candidate from this family to pass the clinical trials. A number of boron-based analogues of (R)-6-O-desmethylantofine have been synthesised. Their physochemical properties were evaluated, same as their in-vitro antiproliferative activity. The pinacol boronate ester derivative (3) showed interesting cytotoxicity against a panel of cancerous cell lines attested by a cancer cell growth-inhibitory potency (GI50) as low as 30 nM.

Antofine suppresses endotoxin-induced inflammation and metabolic disorder via AMP-activated protein kinase.

The inhibition of activated macrophages has been used to develop anti-inflammatory agents for therapeutic intervention to human diseases that cause excessive inflammatory responses. Antofine, a phenanthroindolizidine alkaloid, has a potent anti-inflammatory effect. However, the molecular mechanisms of its anti-inflammatory activity have not yet been fully detailed. In this study, we comprehensively explored the anti-inflammatory effects of antofine on endotoxin-induced inflammation in macrophages using cDNA microarray analysis, thereby elucidating the potential mechanism by which antofine suppresses inflammation. Antofine significantly suppressed the secretion of proinflammatory cytokines such as TNFα and IL-1ß and the production of iNOS in LPS-activated Raw264.7 macrophage cells. In addition, antofine can suppress the expressions of several inflammation-related genes (such as ARG-1, IL1F9, IL-10, and IL-33) and extracellular matrix genes (such as TNC and HYAL1), as well as a vasopressor gene (EDN1) in activated macrophage cells, that are induced by LPS stimulation. The gene expression profiles analyzed by GeneMANIA software showed that antofine not only contributed anti-inflammatory activity but also modulated the cellular metabolism via AMPK. Furthermore, antofine also modulated the activation of AMPK and caspase-1, the key regulator in inflammasome-mediated IL-1ß maturation, in activated macrophage cells. In conclusion, these data indicated that antofine potentially can not only contribute an anti-inflammatory effect but can also attenuate the metabolic disorders induced by inflammation via AMPK.

Antofine, a natural phenanthroindolizidine alkaloid, suppresses angiogenesis via regulation of AKT/mTOR and AMPK pathway in endothelial cells and endothelial progenitor cells derived from mouse embryonic stem cells.

Although antofine, a natural phenanthroindolizidine alkaloid, exerts potential biological activities, including anticancer effect and anti-angiogenic activity, the underlying mechanisms have not yet been investigated. In the present study, the inhibitory effect of antofine on angiogenesis was determined in cultured mouse embryonic stem (mES)/embryoid body (EB)-derived endothelial cells and vascular endothelial growth factor (VEGF)-induced human umbilical vein endothelial cells (HUVECs). Antofine effectively inhibited VEGF-induced cell migration and tube formation of HUVECs. Antofine also significantly decreased ex vivo microvessel sprouting in cultured mouse aortic rings, and inhibited the vascular formation and platelet/endothelial cell adhesion molecule (PECAM) expression of mES/EB-derived cells in 3-D collagen gel. The underlying mechanism of anti-angiogenic activity of antofine was, in part, associated with the modulation of AKT/mTOR and AMP-activated protein kinase (AMPK) signaling in VEGF-stimulated HUVECs.

D and E rings may not be indispensable for antofine: discovery of phenanthrene and alkylamine chain containing antofine derivatives as novel antiviral agents against tobacco mosaic virus (TMV) based on interaction of antofine and TMV RNA.

On the basis of the interaction of antofine and tobacco mosaic virus (TMV) RNA, a series of phenanthrene and alkylamine chain containing antofine derivatives 1-41 were designed, synthesized, and systematically evaluated for their antiviral activity against TMV. The results showed that most of these compounds exhibited good to excellent anti-TMV activity, which indicated that the D and E rings of antofine may not be indispensable. Phenanthrene is important for these compounds, but not the more the better. Phenanthrene, benzene rings, and alkylamine chain containing compounds exhibited good antiviral activity. The optimum compounds, 10, 18, and 19, displayed higher activity than precursor antofine and commercial ribavirin, thus emerging as new lead compounds. The novel concise structure provides another new template for antiviral studies.

Anti-adipogenic activity of the naturally occurring phenanthroindolizidine alkaloid antofine via direct suppression of PPARγ expression.

Antofine (ANTF) is a phenanthroindolizidine alkaloid isolated from the root of Cynanchum paniculatum Kitagawa (Asclepiadaceae), which is used as an herbal remedy for pain and inflammation. ANTF also possesses antiviral and antitumorigenic activities. In this study, we investigated the role of ANTF in adipogenesis. Chronic ABTF administration suppressed adipocyte differentiation and marker expression in a dose-dependent manner. Furthermore, acute administration of ANTF at early stages of differentiation process inhibited lipid droplet formation and adipogenic gene expression. ANTF Treatment decreased expression of PPARγ protein, a master transcription factor in the regulation of adipocyte differentiation, leading to a suppression of aP2 promoter activity. These results suggest that ANTF exerts potent anti-adipogenic effects via direct suppression of PPARγ protein expression, with consequent downregulation of adipogenic gene expression.