Anticancer activity of Kalanchoe tubiflora extract against human lung cancer cells in vitro and in vivo

Kalanchoe pinnata (Lam.) Pers. Leaf ethanolic extract exerts selective anticancer activity through ROS-induced apoptotic cell death in human cancer cell lines

BACKGROUND

The leaves of Kalanchoe pinnata (Lam.) Pers. (K. pinnata), a succulent plant native to tropical regions, are used as a medicinal alternative against cancer in several countries worldwide; however, its therapeutic potential to fight cancer has been little addressed. In this study, we analyzed the phytochemical content, antioxidant capacity, and selectivity of K. pinnata leaf ethanolic extract against different human cancer cell lines in vitro.

METHODOLOGY

This study subjected the ethanolic extract to enzymatic assays to quantify the phytochemical content (phenolics, flavonoids, and anthraquinones) and its radical scavenging and iron-reducing capacities. Also, the phytoconstituents and major phenolic compounds present in the extract's subfractions were identified by GC-MS, HPLC, and NMR. Human cancer (MCF-7, PC-3, HT-29) and normal colon (CoN) cell lines were treated with different concentrations of K. pinnata leaf ethanolic extract, and the changes in cell proliferation (sulforhodamine B assay), caspases activity (FITC-VAD-FMK reporter), mitochondrial membrane potential (MMP, rhodamine 123 assay), chromatin condensation/fragmentation (Hoechst 33342 stain), and ROS generation (DCFH2 probe assay) were assessed.

RESULTS

The results showed that the K. pinnata leaf ethanolic extract is rich in phytoconstituents with therapeutic potential, including phenols (quercetin and kaempferol), flavonoids, fatty acid esters (34.6% of the total composition), 1- triacontanol and sterols (ergosterol and stigmasterol, 15.4% of the total composition); however, it presents a poor content of antioxidant molecules (IC50 = 27.6 mg/mL for H2O2 scavenging activity vs. 2.86 mg/mL in the case of Trolox). Notably, the extract inhibited cell proliferation and reduced MMP in all human cell lines tested but showed selectivity for HT-29 colon cancer cells compared to CoN normal cells (SI = 8.4). Furthermore, ROS generation, caspase activity, and chromatin condensation/fragmentation were augmented significantly in cancer-derived cell lines, indicating a selective cytotoxic effect.

CONCLUSION

These findings reveal that the K. pinnata leaf ethanolic extract contains several bioactive molecules with therapeutic potential, capable of displaying selective cytotoxicity in different human cancer cell lines.

A Review of the Popular Uses, Anatomical, Chemical, and Biological Aspects of Kalanchoe (Crassulaceae): A Genus of Plants Known as "Miracle Leaf"

Species of the genus Kalanchoe have a long history of therapeutic use in ethnomedicine linked to their remarkable healing properties. Several species have chemical and anatomical similarities, often leading to confusion when they are used in folk medicine. This review aims to provide an overview and discussion of the reported traditional uses, botanical aspects, chemical constituents, and pharmacological potential of the Kalanchoe species. Published scientific materials were collected from the PubMed and SciFinder databases without restriction regarding the year of publication through April 2023. Ethnopharmacological knowledge suggests that these species have been used to treat infections, inflammation, injuries, and other disorders. Typically, all parts of the plant are used for medicinal purposes either as crude extract or juice. Botanical evaluation can clarify species differentiation and can enable correct identification and validation of the scientific data. Flavonoids are the most common classes of secondary metabolites identified from Kalanchoe species and can be correlated with some biological studies (antioxidant, anti-inflammatory, and antimicrobial potential). This review summarizes several topics related to the Kalanchoe genus, supporting future studies regarding other unexplored research areas. The need to conduct further studies to confirm the popular uses and biological activities of bioactive compounds is also highlighted.

Potential of Kalanchoe pinnata as a Cancer Treatment Adjuvant and an Epigenetic Regulator

Cancer is a global public health problem that is related to different environmental and lifestyle factors. Although the combination of screening, prevention, and treatment of cancer has resulted in increased patient survival, conventional treatments sometimes have therapeutic limitations such as resistance to drugs or severe side effects. Oriental culture includes herbal medicine as a complementary therapy in combination with chemotherapy or radiotherapy. This study aimed to identify the bioactive ingredients in Kalanchoe pinnata, a succulent herb with ethnomedical applications for several diseases, including cancer, and reveal its anticancer mechanisms through a molecular approach. The herb contains gallic acid, caffeic acid, coumaric acid, quercetin, quercitrin, isorhamnetin, kaempferol, bersaldegenin, bryophyllin a, bryophyllin c, bryophynol, bryophyllol and bryophollone, stigmasterol, campesterol, and other elements. Its phytochemicals participate in the regulation of proliferation, apoptosis, cell migration, angiogenesis, metastasis, oxidative stress, and autophagy. They have the potential to act as epigenetic drugs by reverting the acquired epigenetic changes associated with tumor resistance to therapy-such as the promoter methylation of suppressor genes, inhibition of DNMT1 and DNMT3b activity, and HDAC regulation-through methylation, thereby regulating the expression of genes involved in the PI3K/Akt/mTOR, Nrf2/Keap1, MEK/ERK, and Wnt/β-catenin pathways. All of the data support the use of K. pinnata as an adjuvant in cancer treatment.

Enhancement of Anti-Proliferative Activity of the Extracts from Dehulled Adlay by Fermentation with Bacillus subtilis

Dehulled adlay was fermented with Bacillus subtilis BJ3-2, the anti-proliferative activities of the extracts from fermented dehulled adlay were investigated with six types of tumor cells, and then the bioactive components and the anti-proliferative mechanism were primarily explored. Results showed that all the extracts of B.subtilis-fermented dehulled adlay (BDA) and dehulled adlay (DA) had no inhibition effect on human embryonic kidney 239T cells. The anti-proliferative activities of the extracts from BDA against six types of tumor cells were almost always significantly higher than DA. Compared with others, the n-butanol extract of BDA (BDA-Nb) exhibited stronger anti-proliferative activities against human leukemia K562 cells and human non-small cell lung cancer A549 cells. Importantly, the anti-proliferative activity of fermented dehulled adlay against K562 cells was firstly discovered. Meanwhile, BDA-Nb was rich in tetramethylpyrazine, γ-aminobutyric acid, protocatechuic, 2,3,4-trihydroxybenzoic, chlorogenic, p-hydroxybenzoic, caffeic, trans-cinnamic, ferulic acids, and rutin. BDA-Nb induced the proliferative inhibition of K562 and A549 cells due to abnormal cell morphology, the increased cell population in G1 phase and apoptosis rate, the downregulation of Bcl-2, and the upregulation of Bax and caspase-3/8/9. These results indicate that dehulled adlay fermented with B.subtilis could be a potential therapeutic agent for leukemia and lung cancer.

Synthesis and Rational Design of New Appended 1,2,3-Triazole-uracil Ensembles as Promising Anti-Tumor Agents via In Silico VEGFR-2 Transferase Inhibition

Angiogenesis inhibition is a key step towards the designing of new chemotherapeutic agents. In a view to preparing new molecular entities for cancer treatment, eighteen 1,2,3-triazole-uracil ensembles 5a-r were designed and synthesized via the click reaction. The ligands were well characterized using 1H-, 13C-NMR, elemental analysis and ESI-mass spectrometry. The in silico binding propinquities of the ligands were studied sequentially in the active region of VEGFR-2 using the Molegro virtual docker. All the compounds produced remarkable interactions and potentially inhibitory ligands against VEGFR-2 were obtained with high negative binding energies. Drug-likeness was assessed from the ADME properties. Cytotoxicity of the test compounds was measured against HeLa and HUH-7 tumor cells and NIH/3T3 normal cells by MTT assay. Compound 5h showed higher growth inhibition activity than the positive control, 5-fluorouracil (5-FU), against both HeLa and HUH-7 cells with IC50 values of 4.5 and 7.7 μM respectively. Interestingly, the compounds 5a-r did not show any cytotoxicity towards the normal cell lines. The results advance the position of substituted triazoles in the area of drug design with no ambiguity.

Ethyl acetate subfractions from ethanol extracts of fermented oats (Avena sativa L.) exert anti-cancer properties in vitro and in vivo through G2/M and S Phase arrest and apoptosis

Background: Cancer is a major public problem and poses a long-term impact on patients' life, work, and study. Oats are widely recognized as healthy food and fermented oats were rich in the higher contents of polyphenols. However, the role of fermented oats in cancer remains elusive.

Methods: The effect of ethyl acetate subfractions (EASs) from ethanol extracts of oats fermented by Rhizopus oryzae 3.2751 on cancer cells was verified by series experiments in vitro and in vivo. The cell viability, colony formation, cell cycle, apoptosis, reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and western blot were determined in vitro. The toxicity of EASs and xenograft mouse model were performed in vivo.

Results: MTT assay indicated that EASs interference suppressed the proliferation of four human cancer cells in a dose-dependent manner without a significant impact on two normal cells. EASs (0.2, 0.4, and 0.8 μg/mL) resulted in the G2/M and S phase arrest, apoptosis, depolarization of MMP, and ROS generation in HepG2 cells by flow cytometry. p53, JNK, caspase-9, and caspase-3 were activated and the expression of Bax was promoted, while the expression of Bcl-2 was reduced in HepG2 cells exposed to EASs via western blot. Furthermore, the in vivo study using a xenograft mouse model demonstrated that EASs attenuated the tumor growth with low systemic toxicity.

Conclusions: EASs exhibited anti-cancer activities in vitro and in vivo via cell cycle arrest and apoptosis. This finding suggests that polyphenol-enriched composition from fermented oats might become a promising candidate for impeding the development and progression of liver cancer.

Anticancer Potential of Calli Versus Seedling Extracts Derived from Rosmarinus officinalis and Coleus hybridus

BACKGROUND

In Saudi Arabia, the incidence and mortality rates of breast cancer are high. Although current treatments are effective, breast cancer cells develop resistance to these treatments. Numerous studies have demonstrated that active compounds in plant extracts, such as the phenolic compound Rosmarinic Acid (RA), exert anti-cancer effects.

OBJECTIVE

We investigated the anticancer properties of methanolic crude extracts of seedlings and calli of Rosmarinus officinalis and Coleus hybridus, two Lamiaceae species.

METHODS

MCF-7 human breast cancer cells were treated with methanolic crude extracts obtained from plant calli and seedlings generated in vitro, and cell proliferation was evaluated. Transcriptional profiling of the seedling and callus tissues was also conducted.

RESULTS

The mRNA expression levels of RA genes were higher in C. hybridus seedlings than in R. officinalis seedlings, as well as in C. hybridus calli than in R. officinalis calli, except for TAT and C4H. In addition, seedling and callus extracts of both R. officinalis and C. hybridus showed anti-proliferative effects against MCF-7 cells after 24 or 48 h of treatment.

DISCUSSION

At a low concentration of 10 μg/mL, C. hybridus calli and seedling extracts showed the most significant anti-proliferative effects after 24 and 48 h of exposure (p < 0.01); controls (doxorubicin) also showed significant inhibition, but lesser than that observed with C. hybridus (p < 0.05). Results with R. officinalis callus and seedling extracts did not significantly differ from those with untreated cells.

CONCLUSION

Methanolic extracts of R. officinalis and C. hybridus are potentially valuable options for breast cancer treatment.

Induction of Biosynthetic Genes Related to Rosmarinic Acid in Plant Callus Culture and Antiproliferative Activity Against Breast Cancer Cell Line

BACKGROUND AND OBJECTIVE

Rosmarinic acid is considered as one of the most important secondary metabolites in medicinal plants especially of family Lamiaceae. Rosmarinic acid can prevent both the tumor initiation and promotion stages of carcinogenesis. The aim of current study was to evaluate the antiproliferative effects of Hyssopus officinalis and Thymus vulgaris callus crude extracts contained rosmarinic acid on breast cancer cells with correlation to phenylpropanoid biosynthetic pathway genes expression.

MATERIALS AND METHODS

Calli of both plants were maintained on Murashige and Skoog medium supplemented with kinetin and 2,4-D. Rosmarinic acid was determined spectrophotometrically in both seed-germinated plants (control) and callus tissues. Transcriptional profiling of rosmarinic acid pathway genes was performed with RT-PCR system. The human breast cancer cell line MCF-7 was treated with different levels of crude extracts at different time intervals in order to show their effects on the cell proliferation using a cell viability colorimetric assay (MTT).

RESULTS

The results showed a significant increase of rosmarinic acid content up to 6.5% in callus compared to control. The transcriptional profile of the selected rosmarinic acid genes in callus tissues indicated significant effects on the rosmarinic acid content in both genotypes. T. vulgaris (90 μg mL-1) and H. officinalis (150 μg mL-1) callus extracts had exhibited highest reduction in the cell MCF-7 viability after 48 h of exposure.

CONCLUSION

It was concluded that rosmarinic acid production increased in callus tissue, showed the higher gene expression levels and remarkably inhibited growth of human breast cancer cell line.

Kalantuboside B induced apoptosis and cytoprotective autophagy in human melanoma A2058 cells: An in vitro and in vivo study

Kalantuboside B (KB), a natural bufadienolide derivative extracted from the succulent plant Kalanchoe tubiflora, is well-known for its cardiotonic, immunomodulatory, and anti-inflammatory properties. In this study, we tested in vitro and in vivo anti-cancer efficacy with low concentrations of KB (5-30 ng/mL; 8.7-52.2 nM) on A2058 melanoma cells; and for the molecular mechanisms that underlie them. KB significantly inhibited the cell viability and colony formation via arresting the cell cycle at G2/M phase. There was an association with a decrease in Cyclin A/B1, Cdc25C, and Cdc2 expressions. Further, this treatment indicated the induction of apoptosis, DNA fragmentation, cytochrome c release, and caspase-3, -8, -9, and -12 activation, and PARP cleavage, which shows that mitochondrial, death-receptor, and ER-stress signaling pathways are involved. KB-induced autophagy was apparent from enhanced LC3-II accumulation, GFP-LC3 puncta, and AVO formation. Surprisingly, KB-mediated cell death was potentiated by 3-MA and CQ to suggest the role of autophagy as a cytoprotective mechanism. Moreover, KB-treated A2058 cells enhanced intracellular ROS generation and antioxidant NAC prevented apoptosis and reversed cytoprotective autophagy. Interestingly, KB-induced apoptosis (PARP cleavage) and cytoprotective autophagy (LC3-II accumulation) were mediated by the up-regulation of the ERK signaling pathway. It was also shown that KB promoted cytoprotective autophagy by a calcium dependent-p53 downregulation pathway. In vivo data showed that KB suppressed tumor growth significantly in A2058-xenografted nude mice. A Western blot indicated cell-cycle inhibition (cyclin A reduction), apoptosis induction (PARP cleavage and Bcl-2 inhibition), and cytoprotective autophagy (LC3-II upregulation and p53 downregulation) in KB-treated A2058-xenografted mice. Our findings suggested that KB-induced ROS pathway plays a role in mediating the apoptosis and cytoprotective autophagy in human melanoma cells. Thus, KB is considered to be a putative anti-tumor agent.

Potent antitumor property of Allium bakhtiaricum extracts

BACKGROUND

Allium species are magnificently nutritious and are commonly used as a part of the diet in Iran. They have health enhancing benefits including anticancer properties due to the presence of numerous bioactive compounds. Herein, we investigated in vitro and in vivo anticancer properties of Allium bakhtiaricum extracts.

METHODS

Anti-growth activity of different fractions was explored in vitro on different cancerous cells using MTT assay, Annexin V/PI and SA-β-gal staining, Western blotting, flowcytometric and immunofluorescence microscopic evaluations. In vivo antitumor activity was investigated in BALB/c mice bearing 4 T1 mammary carcinoma cells.

RESULTS

We demonstrated that chloroformic and ethyl acetate fractions exert cytotoxic activity toward MDA-MB-231 cells, the most sensitive cell line, after 72 h of treatment with IC₅₀ values of 0.005 and 0.006 mg/ml, respectively. Incubation of MDA-MB-231 cells with ¼ and ½ IC_50-72h concentrations of each fraction resulted in a significant G2/M cell cycle arrest. ¼ IC_50-72h concentration of the chloroform fraction led to the disruption of polymerization in mitotic microtubules. Exposure of human breast cancer cells to different concentrations of the extracts at different incubation times did not induce apoptosis, autophagy or senescence. Our in vivo study revealed that administration of the chloroform extract at a dose of 1 mg/kg/day strongly suppressed mammary tumor progression and decreased the number of proliferative cells in the lung tissues indicating its anti-metastatic effect.

CONCLUSION

Our findings imply that the chloroform fraction of Allium bakhtiaricum possesses the suppressive action on breast cancer through mitotic cell cycle arrest suggesting a mechanism associated with disturbing microtubule polymerization.

Cytotoxic effect of Kalanchoe flammea and induction of intrinsic mitochondrial apoptotic signaling in prostate cancer cells

ETHNOPHARMACOLOGICAL IMPORTANCE

Kalanchoe flammea Stapf (Crassulaceae) is a medicinal plant grown in the South of Mexico (State of Tabasco), which is commonly used in traditional medicine for the treatment of fever, wounds, inflammation, and cancer.

AIM OF THE STUDY

To establish the potential of K. flammea for the treatment of prostate cancer, evaluating its cytotoxic activity, its probable mechanism of action, and carrying out some toxicological safety studies.

MATERIALS AND METHODS

The cytotoxic activity of the ethyl acetate extract of K. flammea (Kf-EtOAc) was evaluated in several cell lines of prostate cancer by MTT viability assay. The cellular death mechanism was studied by evaluating the translocation of phosphatidylserine (Annexin V); overproduction of reactive oxygen species [2'-7'-Dichlorodihydrofluorescein diacetate (DCFH-DA) assay]; release of Cytochrome C; activation of caspase-3 and -9, and regulation of Bcl-2, XIAP, and PKCε proteins by Western Blot analysis. For the evaluation of the safety of Kf-EtOAc, the Ames test, Micronucleus assay, and acute toxicity study were determined.

RESULTS

Kf-EtOAc exhibited selective cytotoxic activity against prostate cell lines as follows: PC-3, LNCaP, and PrEC (IC₅₀ = 1.36 ± 0.05; 2.06 ± 0.02, and 127.05 ± 0.07 μg/mL, respectively). The F82-P2 fraction (rich in coumaric acid and palmitic acid) obtained by bioassay-guided fractionation of Kf-EtOAc also demonstrated selective cytotoxic activity against PC-3 cells (IC₅₀ = 1.05 ± 0.06 μg/mL). Kf-EtOAc induces apoptosis by the intrinsic pathway; this mechanism of cell death was confirmed after observing that the extract produces phosphatidylserine translocation, overproduction of reactive oxygen species, release of Cytochrome C at mitochondrial level, and activation of caspase-3 and -9. It was also observed that Kf-EtOAc produces significant downregulation of apoptosis-related proteins Bcl-2, XIAP, and PKCε and induces DNA fragmentation and cell cycle arrest. In addition, Kf-EtOAc is non-genotoxic in vitro by Ames test and non-genotoxic in vivo by Micronucleus assay, and no signs of toxicity or death were reported after the administration of a single acute exposure of 2000 mg/kg.

CONCLUSION

K. flammea is a potential candidate for the development of new drugs for the treatment of prostate cancer. However, to propose their use in clinical trials, additional studies are required to understand their pharmacokinetic behavior, as well as the development of a suitable pharmaceutical form.

In vivo and In vitro effects of ethanolic extract of Trigonella foenum-graecum L. seeds on proliferation, angiogenesis and tube formation of endothelial cells

The role of angiogenesis in tumor progression and metastasis formation has been well recognized. Recent studies have reported that Trigonella foenum-graecum L. (fenugreek) seed extracts have potential anticancer properties. The current study was planned to investigate the anti-angiogenic activity of hydroalcoholic extract of fenugreek (HAEF) in vitro and in vivo. Effect of HAEF (50-3000 µg/mL) and thalidomide (200-3000 µmol/L), as a positive control, on the viability of human umbilical vein endothelial cells (HUVECs) and 3T3 fibroblast cells was assessed by thiazolyl blue tetrazolium bromide (MTT) assay. Effect of HAEF on vessel-like tube formation by HUVECs was examined in the matrigel-based assay. Furthermore, the chick chorioallantoic membrane (CAM) was used as in vivo model to study the anti-angiogenic effect of HAEF. HAEF, similar to thalidomide, significantly inhibited the viability of HUVECs and 3T3 cells dose-dependently after 24 h. Moreover, both HAEF and thalidomide significantly reduced tube formation by HUVECs in cell culture condition. In CAM model, HAEF and thalidomide caused a significant decline in the number of neovascular points and in the amount of grades 1 and 2 vessels. These findings revealed that fenugreek has cytotoxic and anti-angiogenic effects in vitro and in vivo. Therefore, this medicinal plant can be subjected to further investigations as antitumor agents.

Excavatolide B inhibits nonsmall cell lung cancer proliferation by altering peroxisome proliferator activated receptor gamma expression and PTEN/AKT/NF-Kβ expression

Marine organisms are proven to be rich source of secondary metabolites that can be used to treat various diseases. Excavatolide B (Exc.B), the most abundant metabolite was found in the marine coral Briareum excavatum exhibits cytotoxic effects against lung cancer cell. Treatment of the A549 cells with Exc.B significantly reduced its cell viability and induced cell cycle arrest at subG1 phase in a dose- and time-dependent manner, respectively. Apoptosis induction by Exc.B was further confirmed by decreased pro-caspase 3 expressions and increased proteolytic cleavage of poly (ADP-ribose) polymerase (PARP) expression. Furthermore, Exc.B increased reactive oxygen species (ROS) and reactive nitrogen species (RNS) and also decreased the antioxidant enzymes such as, Catalase, GPx, SOD, GST, and GSH. The proteomic analysis data revealed that total thirty six proteins were altered by Exc.B. STRING database showed that most of the altered proteins have no interaction between each other. Based on these data, KSR1, RuVBL2, PPAR-γ, and Tenascin X proteins were chosen to validate the 2DE data by Western blotting. Additional experiments demonstrated that Exc.B induced PTEN expression and inhibited pAKT and NF-kB expression. These results provide a novel insight into mechanisms underlying the inhibition of A549 cells growth by excavatolide B. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 290-301, 2017.