α-Tomatine, a novel early-stage autophagy inhibitor, inhibits autophagy to enhance apoptosis via Beclin-1 in Skov3 cells

Dust Fall Microplastics from a Megacity of China Inhibit Autophagy via the PI3K/Akt/mTOR Pathway

The problem of microplastics (MPs) pollution has caused many health risks to residents of Chinese cities. In this study, nine kinds of MPs or microrubbers (MRs) from dust fall (DF) in Xi'an, a megacity in northwestern China, were measured by pyrolysis-gas chromatography-mass spectroscopy, namely, polyethylene, polypropylene, nylon 88, polybutylene, polytetrafluorethylene, polyisoprene, polyvinyl chloride, natural rubber, and synthesis rubber. Here, 51.20% of MPs were extracted from the original DF (samples denoted DF-O). After the subtracting procedure, MPs and their residual (DF-S samples) were divided into two parts. Our results indicated that the DF-O and MPs samples exhibited higher cytotoxicity, inflammatory, and oxidative stress levels than the DF-S samples did. The DF-O and MPs samples suppressed autophagy by decreasing expression levels of microtubule-associated protein light chain 3 (LC3B), p-phosphatidylinositol 3-kinase (p-PI3K), phosphorylated AKT protein (p-Akt), and p-mammalian target of rapamycin (p-mTOR) while increasing the level of p62. Meanwhile, DF-O and MPs samples induced apoptosis through increasing levels of Bax/Bcl-2 and Cleaved Caspase-3/Caspase-3 in Raw264.7 cells. These trends could be reversed through removing half of the MPs in DF-O. Therefore, dust fall microplastics inhibited autophagy and induced apoptosis via activating the PI3K/Akt/mTOR pathway, increasing the Bax/Bcl-2 and Cleaved Caspase-3/Caspase-3 ratios. Here we provide a comprehensive perspective into the studies of atmospheric MPs pollution status and mechanisms of inhalation toxicity for health risk assessment of MPs in DF.

Saponins, the Unexplored Secondary Metabolites in Plant Defense: Opportunities in Integrated Pest Management

Plants are exposed to a diverse range of biotic stressors, including fungi, bacteria, nematodes, insects and viruses. To combat these enemies, plants have developed an arsenal of defense mechanisms over time, among which secondary metabolites are the most effective. Moreover, to overcome the negative impact of chemical pesticides, the plant's secondary metabolites can be harnessed to develop novel disease management strategies. Alkaloids, flavonoids, terpenes and essential oils are major pathogen/pest-responsive secondary metabolite classes in plants. Among these, saponins have shown significant potential in suppressing a wide range of plant pathogens. However, they are yet to be explored thoroughly compared to other secondary metabolites in plant defense, and therefore, a low number of disease control agents exist in agri-markets based on saponins. Thus, this review aims to rectify this bias by identifying and acknowledging the significance of saponins as being on par with other classes of secondary metabolites in plant defense systems. It also provides the first holistic review on the role of saponins with known mechanisms against all of the major plant pathogens/pests. Furthermore, this review discusses the potential of saponin-rich crops in providing eco-friendly pest/pathogen management products for integrated pest management (IPM) and prospectives on the potential of saponin derivatives in developing novel biocides for sustainable agriculture.

Advancements in programmed cell death research in antitumor therapy: a comprehensive overview

Cell death is a normal physiological process within cells that involves multiple pathways, such as normal DNA damage, cell cycle arrest, and programmed cell death (PCD). Cell death has been a hot spot of research in tumor-related fields, especially programmed cell death, which is a key form of cell death and is classified into different types according to the mechanism of occurrence, such as apoptosis, autophagy, necroptosis, pyroptosis, ferroptosis, and disulfidptosis. Given the important role of PCD in maintaining tissue homeostasis and inhibiting tumorigenesis and development, more and more basic and clinical studies are devoted to revealing its potential application in anti-tumor strategies. The purpose of this review is to systematically review the regulatory mechanisms of PCD and to summarize the latest research progress of anti-tumor treatment strategies based on PCD.

Tomatidine, a Steroidal Alkaloid, Synergizes with Cisplatin to Inhibit Cell Viability and Induce Cell Death Selectively on FLT3-ITD+ Acute Myeloid Leukemia Cells

BACKGROUND

Acute Myeloid Leukemia (AML) is a hematological cancer that frequently presents with a range of side effects and drug resistance during anticancer drug treatment. The current study aims to achieve increased efficacy by combining lower doses of cisplatin with increasing concentrations of tomatidine in AML cells to increase efficacy.

METHODS

Anti-proliferative effects of single and combination of cisplatin and tomatidine were assessed via MTT cell viability assay. The Annexin V/Propidium Iodide Double Staining method was used to measure the apoptotic effects of combined tomatidine and cisplatin treatment. Then, Western Blot analysis was performed to measure Poly (ADP-ribose) polymerase (PARP) and Caspase-3 protein expression levels.

RESULTS

Cisplatin treatment with lower concentrations displayed high cytotoxic effects on AML cells, compared with tomatidine. The combination of the Inhibitory Concentration (IC) 20 value of cisplatin and increasing doses of tomatidine exhibited a significant decrease in cell viability relative to single treatments. The combination index analysis revealed a mild synergistic effect of cisplatin IC20 and varying tomatidine doses. The apoptosis induced when cisplatin was combined with 500 µM tomatidine by almost 20%, while the percentage of apoptosis in combination with 1 mM tomatidine was measured by 50% for both cell lines. The upregulation of proapoptotic cleaved-PARP (3.2 and 1.08-fold for THP-1 and MOLM-13, respectively) and downregulation in Caspase-3 (0.23 and 0.13-fold for THP-1 and MOLM-13, respectively) was detected.

CONCLUSIONS

Together, the study indicated that when tomatidine combined with cisplatin on AML cell lines, a combinatorial anti-proliferative and apoptotic effect is observed. The combination of cisplatin with tomatidine may be a promising approach.

The Emerging Role of Natural Products in Cancer Treatment

The exploration of natural products as potential agents for cancer treatment has garnered significant attention in recent years. In this comprehensive review, we delve into the diverse array of natural compounds, including alkaloids, carbohydrates, flavonoids, lignans, polyketides, saponins, tannins, and terpenoids, highlighting their emerging roles in cancer therapy. These compounds, derived from various botanical sources, exhibit a wide range of mechanisms of action, targeting critical pathways involved in cancer progression such as cell proliferation, apoptosis, angiogenesis, and metastasis. Through a meticulous examination of preclinical and clinical studies, we provide insights into the therapeutic potential of these natural products across different cancer types. Furthermore, we discuss the advantages and challenges associated with their use in cancer treatment, emphasizing the need for further research to optimize their efficacy, pharmacokinetics, and delivery methods. Overall, this review underscores the importance of natural products in advancing cancer therapeutics and paves the way for future investigations into their clinical applications.

Main chemical constituents and mechanism of anti-tumor action of Solanum nigrum L

OBJECTIVE

Solanum nigrum L. (SNL) is a natural drugwith diverse bioactive components and multi-targeted anti-tumor effects, gaining increasing attention in clinical application.

METHOD AND RESULTS

This paper reviews the studies on SNL by searching academic databases (Google Scholar, PubMed, Science Direct,and Web of Science, among others), analyzing its chemical compositions (alkaloids, saponins, polysaccharides, and polyphenols, among others), andbriefly describes the anti-tumor mechanisms of the main components.

DISCUSSION

This paper discusses the shortcomings of the current research on SNL and proposes corresponding solutions, providing theoretical support for further research on its biological functions and clinical efficacy.

Review on toxicology and activity of tomato glycoalkaloids in immature tomatoes

Owing to the lack of selection and limited intelligence in mechanical picking, some immature tomatoes that contain alkaloids are thrown away. Tomatine alkaloids are steroidal alkaloids naturally present in Solanaceae plants, which are distributed in small amounts in immature tomato fruits and decrease as the fruits ripen. Tomato glycoalkaloids are harmful to human health. However, in small quantities, there is some evidence that these compounds might be beneficial, as other non-antioxidant bioactivities. This article considers recent research on the biological effects of tomato glycoalkaloids in immature tomatoes, providing reference value for the potential development of these compounds.

Therapeutic Potential of Solanum Alkaloids with Special Emphasis on Cancer: A Comprehensive Review

Cancer has emerged as a formidable global health challenge, with treatment methods like chemotherapy and radiation often exacerbating the situation due to their associated side effects. Opting for natural sources like plants as a safer and environmentally friendly alternative seems promising. Historically, plants have served as valuable sources for treating diverse health conditions, attributable to their rich composition of therapeutic phytochemicals. Within this array of phytochemicals, alkaloids, especially those found in the Solanaceae plant family, are notably prominent. Alkaloids from Solanaceae plant family called Solanum alkaloids demonstrate noteworthy anti-tumour characteristics and exert a potent inhibitory influence on cancer cell proliferation. They trigger programmed cell death in cancerous cells through various molecular pathways, whether administered alone or combined with other medications. Solanum alkaloids act upon cancer cells via multiple mechanisms, including apoptosis induction, suppression of cell growth and migration, as well as inhibition of angiogenesis. This review provides insights into the anti-cancer attributes of Solanum alkaloids found in various Solanum plant species, along with a brief overview of their other medicinal properties.

Advances in antitumor activity and mechanism of natural steroidal saponins: A review of advances, challenges, and future prospects

BACKGROUND

Cancer, the second leading cause of death worldwide following cardiovascular diseases, presents a formidable challenge in clinical settings due to the extensive toxic side effects associated with primary chemotherapy drugs employed for cancer treatment. Furthermore, the emergence of drug resistance against specific chemotherapeutic agents has further complicated the situation. Consequently, there exists an urgent imperative to investigate novel anticancer drugs. Steroidal saponins, a class of natural compounds, have demonstrated notable antitumor efficacy. Nonetheless, their translation into clinical applications has remained unrealized thus far. In light of this, we conducted a comprehensive systematic review elucidating the antitumor activity, underlying mechanisms, and inherent limitations of steroidal saponins. Additionally, we propose a series of strategic approaches and recommendations to augment the antitumor potential of steroidal saponin compounds, thereby offering prospective insights for their eventual clinical implementation.

PURPOSE

This review summarizes steroidal saponins' antitumor activity, mechanisms, and limitations.

METHODS

The data included in this review are sourced from authoritative databases such as PubMed, Web of Science, ScienceDirect, and others.

RESULTS

A comprehensive summary of over 40 steroidal saponin compounds with proven antitumor activity, including their applicable tumor types and structural characteristics, has been compiled. These steroidal saponins can be primarily classified into five categories: spirostanol, isospirostanol, furostanol, steroidal alkaloids, and cholestanol. The isospirostanol and cholestanol saponins are found to have more potent antitumor activity. The primary antitumor mechanisms of these saponins include tumor cell apoptosis, autophagy induction, inhibition of tumor migration, overcoming drug resistance, and cell cycle arrest. However, steroidal saponins have limitations, such as higher cytotoxicity and lower bioavailability. Furthermore, strategies to address these drawbacks have been proposed.

CONCLUSION

In summary, isospirostanol and cholestanol steroidal saponins demonstrate notable antitumor activity and different structural categories of steroidal saponins exhibit variations in their antitumor signaling pathways. However, the clinical application of steroidal saponins in cancer treatment still faces limitations, and further research and development are necessary to advance their potential in tumor therapy.

Zinc oxide nanoparticles inhibit malignant progression and chemotherapy resistance of ovarian cancer cells by activating endoplasmic reticulum stress and promoting autophagy

The mortality rate of ovarian cancer (OC) is high, posing a serious threat to women's lives. Zinc oxide nanoparticles (ZnO-NPs) show great potential in the treatment of cancer. However, the mechanism of ZnO-NPs in inhibiting the malignant proliferation and chemotherapy resistance of OC has remained elusive. In the present study, ZnO-NPs at different concentrations were used to treat SKOV3 cells, and subsequently, analyses including the Cell Counting Kit-8 assay, EDU staining, colony-formation assay, flow cytometry, wound-healing assay, Transwell assay and western blot were used to detect cell proliferation, invasion, migration, epithelial-mesenchymal transition (EMT) and chemotherapy resistance, as well as endoplasmic reticulum stress (ERS)- and autophagy-related indicators. Finally, the mechanisms of action of ZnO-NPs on OC were examined by adding ERS inhibitor 4-phenylbutyric acid (4-PBA) and autophagy inhibitor 3-methyladenine (3-MA). It was found that ZnO-NPs inhibited SKOV3 cell proliferation, facilitated apoptosis and induced cell cycle arrest. Furthermore, ZnO-NPs inhibited the invasion, migration and EMT of SKOV3 cells. ZnO-NPs also inhibited chemotherapy resistance of SKOV3 cells. ZnO-NPs activated ERS and promoted autophagy. The addition of 4-PBA or 3-MA significantly reversed the effects of ZnO-NPs on SKOV3 cells. Overall, ZnO-NPs inhibit the malignant progression and the chemotherapy resistance of SKOV3 cells by activating ERS and promoting autophagy.

The Therapeutic Value of Solanum Steroidal (Glyco)Alkaloids: A 10-Year Comprehensive Review

Steroidal (glycol)alkaloids S(G)As are secondary metabolites made of a nitrogen-containing steroidal skeleton linked to a (poly)saccharide, naturally occurring in the members of the Solanaceae and Liliaceae plant families. The genus Solanum is familiar to all of us as a food source (tomato, potato, eggplant), but a few populations have also made it part of their ethnobotany for their medicinal properties. The recent development of the isolation, purification and analysis techniques have shed light on the structural diversity among the SGAs family, thus attracting scientists to investigate their various pharmacological properties. This review aims to overview the recent literature (2012-2022) on the pharmacological benefits displayed by the SGAs family. Over 17 different potential therapeutic applications (antibiotic, antiviral, anti-inflammatory, etc.) were reported over the past ten years, and this unique review analyzes each pharmacological effect independently without discrimination of either the SGA's chemical identity or their sources. A strong emphasis is placed on the discovery of their biological targets and the subsequent cellular mechanisms, discussing in vitro to in vivo biological data. The therapeutic value and the challenges of the solanum steroidal glycoalkaloid family is debated to provide new insights for future research towards clinical development.

Physiological functions, pharmacological aspects and nutritional importance of green tomato- a future food

Green tomatoes contain significant levels of steroidal glycoalkoids (SGA) such as α-tomatine and green pigment chlorophyll. Tomatine is an admixture of two glycoalkoids; alpha tomatine and dehydrotomatine reported various health beneficial biological activities. Moreover, a hydrolyzed product of tomatine also contributes to age-related atrophy, and muscle weakness and helps the elderly recover from illness and injuries related to age. However, there is a lack of evidence regarding the absorption of tomatine in the human body concerning proposed biological activity, which should be an area of interest in the future. Once, the absorption study is established compounds concentrated in green tomatoes are potentially involved as protective compounds for several diseases and also used for functional food. To facilitate the use of green tomatoes in food processing, this comprehensive review provides data on the nutritional value of green tomatoes, with emphasis on the evolution of the physiological chemistry, analytical, medicinal, and pharmacological effects of the α-tomatine and chlorophyll in an experimental model. The broad aim of this review is to evaluate the health benefits of green tomatoes in addition to their nutritional value and to study the several features of the role of α-tomatine and chlorophyll in human health.

Anticancer activity of glycoalkaloids from Solanum plants: A review

Cancer is still one of the main causes of death worldwide. For this reason, new compounds that have chemotherapeutic potential have been identified. One such group of substances is Solanaceae glycoalkaloids (GAs). They are natural compounds produced by plants widely used in traditional medicine for healing many disorders. Among others, GAs exhibit significant antitumor properties, for example, a strong inhibitory effect on cancer cell growth. This activity can result in the induction of tumor cell apoptosis, which can occur via different molecular pathways. The molecular mechanisms of the action of GAs are the subject of intensive research, as improved understanding could lead to the development of new cancer therapies. The genetic basis for the formation of neoplasms are mutations in protooncogenes, suppressors, and apoptosis-controlling and repair genes; therefore, substances with antineoplastic properties may affect the levels of their expression or the levels of their expression products. Therapeutic compounds can be applied separately or in combination with other drugs to increase the efficiency of cancer therapy; they can act on the cell through various mechanisms at different stages of carcinogenesis, inducing the process of apoptosis, blocking cell proliferation and migration, and inhibiting angiogenesis. This review summarizes the newest studies on the anticancer properties of solanine (SN), chaconine (CH), solasonine (SS), solamargine (SM), tomatine (TT) and their extracts from Solanum plants.

Recent advances in glioblastoma multiforme therapy: A focus on autophagy regulation

Despite conventional treatment options including chemoradiation, patients with the most aggressive primary brain tumor, glioblastoma multiforme (GBM), experience an average survival time of less than 15 months. Regarding the malignant nature of GBM, extensive research and discovery of novel treatments are urgently required to improve the patients' prognosis. Autophagy, a crucial physiological pathway for the degradation and recycling of cell components, is one of the exciting targets of GBM studies. Interventions aimed at autophagy activation or inhibition have been explored as potential GBM therapeutics. This review, which delves into therapeutic techniques to block or activate autophagy in preclinical and clinical research, aims to expand our understanding of available therapies battling GBM.

Content of Two Major Steroidal Glycoalkaloids in Tomato (Solanum lycopersicum cv. Micro-Tom) Mutant Lines at Different Ripening Stages

Esculeoside A and tomatine are two major steroidal alkaloids in tomato fruit (Solanum lycopersicum) that exhibit anti-inflammatory, anticancer, and anti-hyperlipidemia activities. Tomatine contained in immature tomato fruit is converted to esculeoside A as the fruit matures. To develop new tomato varieties based on the content analysis of functional secondary metabolites, 184 mutant lines were generated from the original cultivar (S. lycopersicum cv. Micro-Tom) by radiation breeding. Ultra-performance liquid chromatography coupled with evaporative light scattering detector was used to identify the mutant lines with good traits by analyzing tomatine and esculeoside A content. Compared with the original cultivar, candidates for highly functional cultivars with high esculeoside A content were identified in the mature fruit of the mutant lines. The mutant lines with low and high tomatine content at an immature stage were selected as edible cultivars due to toxicity reduction and as a source of tomatine with various pharmacological activities, respectively. During the process of ripening from green to red tomatoes, the rate of conversion of tomatine to esculeoside A was high in the green tomatoes with a low tomatine content, whereas green tomatoes with a high tomatine content exhibited a low conversion rate. Using methanol extracts prepared from unripe and ripe fruits of the original cultivar and its mutant lines and two major compounds, we examined their cytotoxicity against FaDu human hypopharynx squamous carcinoma cells. Only tomatine exhibited cytotoxicity with an IC₅₀ value of 5.589 μM, whereas the other samples did not exhibit cytotoxicity. Therefore, radiation breeding represents a useful tool for developing new cultivars with high quality, and metabolite analysis is applicable for the rapid and objective selection of potential mutant lines.

In Vivo and in vitro antitumor activity of tomatine in hepatocellular carcinoma

Background: There is abundant ethnopharmacological evidence the uses of regarding Solanum species as antitumor and anticancer agents. Glycoalkaloids are among the molecules with antiproliferative activity reported in these species.

Purpose: To evaluate the anticancer effect of the Solanum glycoalkaloid tomatine in hepatocellular carcinoma (HCC) in vitro (HepG2 cells) and in vivo models.

Methods: The resazurin reduction assay was performed to detect the effect of tomatine on cell viability in human HepG2 cell lines. Programmed cell death was investigated by means of cellular apoptosis assays using Annexin V. The expression of cancer related proteins was detected by Western blotting (WB). Reactive oxygen species (ROS) and calcium were determined by 2,7-dichlorodihydrofluorescein diacetate and Fluo-4, respectively. Intrahepatic HepG2 xenograft mouse model was used to elucidate the effect of tomatine on tumor growth in vivo.

Results and Discussion: Tomatine reduced HepG2 cell viability and induced the early apoptosis phase of cell death, consistently with caspase-3, -7, Bcl-2 family, and P53 proteins activation. Furthermore, tomatine increased intracellular ROS and cytosolic Ca⁺² levels. Moreover, the NSG mouse xenograft model showed that treating mice with tomatine inhibited HepG2 tumor growth.

Conclusion: Tomatine inhibits in vitro and in vivo HCC tumorigenesis in part via modulation of p53, Ca⁺², and ROS signalling. Thus, the results suggest the potential cancer therapeutic use of tomatine in HCC patients.

Cancer cell's internal and external warriors: Autophagosomes and exosomes

"That survival instinct, that will to live, that need to get back to life again, is more powerful than any consideration of taste, decency, politeness, manners, civility, anything. It's such a powerful force." This quote by famous director Danny Boyle is a perfect analogy to describe the cancer cell's inexhaustible drive to persist against all odds. In order to adapt to a hostile environment, the cancer cells rely on multiple mechanisms including immune escape, epithelial to mesenchymal transition, angiogenesis, extravasation, autophagy, exosome release among others. Cancer cells depute their internal and external warriors, autophagosomes and exosomes, to dwell in the belligerent tumor microenvironment. It is quite reasonable for a cancer cell, striving to survive, to invest in pathways that will provide the maximum advantage. Autophagy is an important cellular degradation pathway, while the exosome pathway provides an alternative cargo disposal mechanism to maintain the homeostasis and cell survival. While autophagic degradation provides the essential nutrients to rapidly dividing cells, exosomal secretion ensures that the tumor microenvironment is attuned to accommodate the swiftly expanding tumor mass. Studies have revealed that exosomes secreted by cancer cells can modulate autophagy in recipient cells, while autophagy can influence the biogenesis of exosomes. Autophagy and exosome crosstalk is extremely complex and it is only beginning to be recognized and documented. This review is focused on discussing the roles of autophagy and exosomes in the cancer cell's adaptation to the tumor microenvironment and how the two pathways are coordinately regulated to facilitate cancer cell survival.

The steroidal alkaloids α-tomatine and tomatidine: Panorama of their mode of action and pharmacological properties

The steroidal glycoalkaloid α-tomatine (αTM) and its aglycone tomatidine (TD) are abundant in the skin of unripe green tomato and present in tomato leaves and flowers. They mainly serve as defensive agents to protect the plant against infections by insects, bacteria, parasites, viruses, and fungi. In addition, the two products display a range of pharmacological properties potentially useful to treat various human diseases. We have analyzed all known pharmacological activities of αTM and TD, and the corresponding molecular targets and pathways impacted by these two steroidal alkaloids. In experimental models, αTM displays anticancer effects, particularly strong against androgen-independent prostate cancer, as well as robust antifungal effects. αTM is a potent cholesterol binder, useful as a vaccine adjuvant to improve delivery of protein antigens or therapeutic oligonucleotides. TD is a much less cytotoxic compound, able to restrict the spread of certain viruses (such as dengue, chikungunya and porcine epidemic diarrhea viruses) and to provide cardio and neuro-protective effects toward human cells. Both αTM and TD exhibit marked anti-inflammatory activities. They proceed through multiple signaling pathways and protein targets, including the sterol C24 methyltransferase Erg6 and vitamin D receptor, both directly targeted by TD. αTM is a powerful regulator of the NFkB/ERK signaling pathway implicated in various diseases. Collectively, the analysis shed light on the multitargeted action of αTM/TD and their usefulness as chemo-preventive or chemotherapeutic agents. A novel medicinal application for αTM is proposed.