Comparison of cytotoxic activities of extracts from Selaginella species

Siamenflavones A-C, three undescribed biflavonoids from Selaginella siamensis Hieron. and biflavonoids from spike mosses as EGFR inhibitor

Three undescribed biflavonoids (BFVs), siamenflavones A-C along with twelve BFVs were isolated from Selaginella siamensis Hieron. and Selaginella bryopteris (L.) Baker (Selaginellaceae). The chemical structures of undescribed compounds were established through comprehensive spectroscopic techniques, chemical correlations, and X-ray crystallography. The ten isolated BFVs, siamenflavones A-C, delicaflavone, chrysocauflavone, robustaflavone, robustaflavone-4-methylether, amentoflavone, tetrahydro-amentoflavone, and sciadopitysin were evaluated for the antiproliferative effects against four human cancer cell lines A549, H1975, HepG2 and T47D. Delicaflavone and robustaflavone 4'-methylether exerted strong effects on the four human cancer cell lines. Siamenflavone B, delicaflavone and robustaflavone 4'-methylether showed potent inhibitory activities against wild-type EGFR. The inhibition of the compounds was further supported by molecular docking and predictive intermolecular interactions. Molecular dynamics simulation studies of siamenflavone B and robustaflavone-4'-methylether complexed to EGFR-TK further supported inhibition of the compounds to the ATP binding site. Finally, analysis of pharmacokinetic and electronic properties using density-functional theory and known drug index calculations suggest that the compounds are pharmaceutically compatible for drug administration.

Traditional Medicinal Plants Conferring Protection Against Ovalbumin-Induced Asthma in Experimental Animals: A Review

Asthma is a chronic inflammatory disease of the respiratory tract in which the numerous immune cells, including eosinophils, neutrophils, macrophages, T-lymphocytes, mast cells and epithelial lining play key roles. The numerous anti-asthmatic drugs are available in modern medicine to treat asthma, but they have several disadvantages, including side effects and the cost variations, which compromise treatment compliance. The literature review reveals that traditional herbal medicines have good potential as alternative treatment and management for asthma. However, communities hesitated to use the traditional herbal medicines due to lack of established mechanism of action about their anti-asthmatic potential. The present review aimed to summarise the information stated in the literature about the potential effect of traditional medicinal plants (TMPs) conferring protection against ovalbumin (OVA)-induced asthma model. The literature search was conducted in database like PubMed, Scopus, Google Scholar and ScienceDirect. After screening through the literature from 2011 to date, a total of 27 medicinal plants and two polyherbal extracts have been reported to be used as traditional herbal medicines and also utilised to be tested against OVA-induced asthma, were included. We found them to be an important alternative source of treatment for asthma, since some have comparable efficacies with drugs commonly used in the modern system against asthma. All the reported medicinal plants confirmed their traditional use against asthma or its related inflammation. The present review provides faith in traditional information and also offers new insight into the potential of natural products against asthma.

Phytochemistry, Bioactivities, Pharmacokinetics and Toxicity Prediction of Selaginella repanda with Its Anticancer Potential against Human Lung, Breast and Colorectal Carcinoma Cell Lines

In this study, we investigated the bioactive potential (antibacterial and antioxidant), anticancer activity and detailed phytochemical analysis of Selaginellarepanda (S. repanda) ethanolic crude extract for the very first time using different in vitro approaches. Furthermore, computer-aided prediction of pharmacokinetic properties and safety profile of the identified phytoconstituents were also employed in order to provide some useful insights for drug discovery. S. repanda, which is a rich source of potent natural bioactive compounds, showed promising antibacterial activity against the tested pathogenic bacteria (S. aureus, P. aeruginosa, E. coli and S. flexneri). The crude extract displayed favorable antioxidant activity against both 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC₅₀ = 231.6 μg/mL) and H₂O₂ (IC₅₀ = 288.3 μg/mL) molecules. S. repanda also showed favorable and effective anticancer activity against all three malignant cancer cells in a dose/time dependent manner. Higher activity was found against lung (A549) (IC₅₀ = 341.1 μg/mL), followed by colon (HCT-116) (IC₅₀ = 378.8 μg/mL) and breast (MCF-7) (IC₅₀ = 428.3 μg/mL) cancer cells. High resolution-liquid chromatography–mass spectrometry (HR-LC–MS) data of S. repanda crude extract revealed the presence of diverse bioactive/chemical components, including fatty acids, alcohol, sugar, flavonoids, alkaloids, terpenoids, coumarins and phenolics, which can be the basis and major cause for its bioactive potential. Therefore, achieved results from this study confirmed the efficacy of S. repanda and a prospective source of naturally active biomolecules with antibacterial, antioxidant and anticancer potential. These phytocompounds alone with their favorable pharmacokinetics profile suggests good lead and efficiency of S. repanda with no toxicity risks. Finally, further in vivo experimental investigations can be promoted as probable candidates for various therapeutic functions, drug discovery and development.

Comparison of Chemical Composition and Biological Activities of Eight Selaginella Species

Selaginella P. Beauv. is a group of vascular plants in the family Selaginellaceae Willk., found worldwide and numbering more than 700 species, with some used as foods and medicines. The aim of this paper was to compare methanolic (MeOH) and dichloromethane (DCM) extracts of eight Selaginella species on the basis of their composition and biological activities. Six of these Selaginella species are underinvestigated. Using ultra-high performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) analysis, we identified a total of 193 compounds among the tested Selaginella species, with flavonoids predominating. MeOH extracts recovered more constituents that were detected, including selaginellins, the occurrence of which is only typical for this plant genus. Of all the tested species, Selaginella apoda contained the highest number of identified selaginellins. The majority of the compounds were identified in S. apoda, the fewest compounds in Selaginella cupressina. All the tested species demonstrated antioxidant activity using oxygen radical absorption capacity (ORAC) assay, which showed that MeOH extracts had higher antioxidant capacity, with the half maximal effective concentration (EC₅₀) ranging from 12 ± 1 (Selaginella myosuroides) to 124 ± 2 (Selaginella cupressina) mg/L. The antioxidant capacity was presumed to be correlated with the content of flavonoids, (neo)lignans, and selaginellins. Inhibition of acetylcholinesterase (AChE) was mostly discerned in DCM extracts and was only exhibited in S. myosuroides, S. cupressina, Selaginella biformis, and S. apoda extracts with the half maximal inhibitory concentration (IC₅₀) in the range of 19 ± 3 to 62 ± 1 mg/L. Substantial cytotoxicity against cancer cell lines was demonstrated by the MeOH extract of S. apoda, where the ratio of the IC₅₀ HEK (human embryonic kidney) to IC₅₀ HepG2 (hepatocellular carcinoma) was 7.9 ± 0.2. MeOH extracts inhibited the production of nitrate oxide and cytokines in a dose-dependent manner. Notably, S. biformis halved the production of NO, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 at the following concentrations: 105 ± 9, 11 ± 1, and 10 ± 1 mg/L, respectively. Our data confirmed that extracts from Selaginella species exhibited cytotoxicity against cancer cell lines and AChE inhibition. The activity observed in S. apoda was the most promising and is worth further exploration.

A biflavonoid-rich extract from Selaginella moellendorffii Hieron. induces apoptosis via STAT3 and Akt/NF-κB signalling pathways in laryngeal carcinoma

Selaginella moellendorffii Hieron. (SM), a perennial evergreen plant, has been used in the treatment of acute infectious hepatitis, thoracic and hypochondriac lumbar contusions, systemic oedema and thrombocytopaenia. However, the role of a biflavonoid-rich extract from SM (SM-BFRE) in anti-larynx cancer has rarely been reported. In this study, the in vitro and in vivo anti-laryngeal cancer activity and potential mechanisms of SM-BFRE were investigated. An off-line semipreparative liquid chromatography-nuclear magnetic resonance protocol was carried out to determine six biflavonoids from SM-BFRE. In vitro, MTT assay revealed that SM-BFRE inhibited the proliferation of laryngeal carcinoma cells. A wound healing assay indicated that SM-BFRE suppressed the migration of laryngeal cancer cells. Hoechst 33 258 and Annexin V-FITC/PI double staining assays were performed and verified that SM-BFRE induced apoptosis in laryngeal carcinoma cells. The Hep-2 bearing nude mouse model confirmed that SM-BFRE also exhibited anticancer effect in vivo. In addition, Western blot analysis demonstrated that SM-BFRE exerted its anti-laryngeal cancer effect by activating the mitochondrial apoptotic pathway and inhibiting STAT3 and Akt/NF-κB signalling pathways. All results suggested that SM-BFRE could be considered as a potential chemotherapeutic drug for laryngeal cancer.

Robustaflavone induces G0/G1 cell cycle arrest and apoptosis in human umbilical vein endothelial cells and exhibits anti-angiogenic effects in vivo

We investigated the anti-angiogenic and pro-apoptotic effects of robustaflavone (RF), a naturally occurring biflavonoid, on human umbilical vein endothelial cells (HUVECs). RF inhibited HUVEC proliferation and showed cytotoxicity that inhibited HUVEC viability. RF-induced apoptosis was characterized by flow cytometry and caspase 3 analysis. We found that RF increased the number of sub-G1 cells and terminal deoxynucleotidyl transferase dUTP nick end-labeled cells. Additionally, RF induced caspase 3 and poly (ADP-ribose) polymerase activation. Potential molecular targets were identified using a human apoptosis antibody array. RF upregulated Bax, Bad, cleaved caspase 3, p21, and phosphorylated p53 levels. RF induced mitochondrial membrane potential loss and the release of cytochrome c and apoptosis-inducing factor. Cell cycle arrest at G0/G1 phase and the downregulation of Cdk4, Cdk6, and cyclin D1 expression were induced by RF. In vivo anti-angiogenic effects were investigated using a tumor allograft animal model and a Matrigel plug assay. RF reduced the volumes and weights of CT-26 cell-derived tumors. The blood vessel density was significantly decreased in RF-treated tumors. RF also inhibited VEGF-A-stimulated blood vessel formation in vivo in Matrigel plugs. These results suggest that RF can potentially inhibit angiogenesis-dependent tumor growth and metastasis.

Robustaflavone-4'-dimethyl ether from Selaginella uncinata attenuated lipopolysaccharide-induced acute lung injury via inhibiting FLT3-mediated neutrophil activation

Neutrophils act as both messenger and effector which contributed to the pathogenesis of acute lung injury (ALI). Targeting neutrophils could be a novel strategy for prevention and treatment of ALI. Selaginella uncinata is widely used as an antitussive, antipyretic and anti-inflammatory herb to treat various pulmonary diseases, including lung cancer, asthma, pulmonary fibrosis and pneumonia. However, its effective constituents remain unknown. In the present study, the protective effects of flavonoids from S. uncinata (SUF) and its major compound robustaflavone-4'-dimethyl ether (RDE) against lipopolysaccharide (LPS)-induced ALI were investigated in mice and in neutrophils.The results showed that both SUF and RDE had the same inhibition on LPS-induced lung edema and neutrophil infiltration as well as the increased levels of IL-6, TNF-α, P-selectin and ICAM-1 in serum of LPS-challenged mice. Furthermore, RDE significantly inhibited inducible neutrophil activation in a concentration-dependent manner, and also reduced the levels of intracellular calcium as well as the expressions of CCR2. Rescue experiment showed that RDE suppressed FLT3 and its downstream p-p38 and p-AKT, which could be abolished by FLT3 agonist FLT3L but partly by MAPK agonist PDBu or AKT agonist SC79. Therefore, these results indicated that RDE as the main bioactive compound in SUF alleviated LPS-induced acute lung injury and inhibited neutrophil activation via inhibition of FLT3-mediatied AKT and MAPK pathways.

A review of the use of pteridophytes for treating human ailments

The aim of this review was to explore the pharmacological activity of early tracheophytes (pteridophytes) as an alternative medicine for treating human ailments. As the first vascular plants, pteridophytes (aka, ferns and fern allies) are an ancient lineage, and human beings have been exploring and using taxa from this lineage for over 2000 years because of their beneficial properties. We have documented the medicinal uses of pteridophytes belonging to thirty different families. The lycophyte Selaginella sp. was shown in earlier studies to have multiple pharmacological activity, such as antioxidant, anti-inflammatory, anti-cancer, antidiabetic, antiviral, antimicrobial, and anti-Alzheimer properties. Among all the pteridophytes examined, taxa from the Pteridaceae, Polypodiaceae, and Adiantaceae exhibited significant medicinal activity. Based on our review, many pteridophytes have properties that could be used in alternative medicine for treatment of various human illnesses. Biotechnological tools can be used to preserve and even improve their bioactive molecules for the preparation of medicines against illness. Even though several studies have reported medicinal uses of ferns, the possible bioactive compounds of several pteridophytes have not been identified. Furthermore, their optimal dosage level and treatment strategies still need to be determined. Finally, the future direction of pteridophyte research is discussed.

Analysis of the Total Biflavonoids Extract from Selaginella doederleinii by HPLC-QTOF-MS and Its In Vitro and In Vivo Anticancer Effects

Selaginella doederleinii Hieron has been traditionally used as a folk antitumor herbal medicine in China. In this paper, the phytochemical components of the total biflavonoids extract from S. doederleinii were studied by using high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF MS/MS) in negative ion mode, and their in vitro and in vivo anticancer effects were evaluated. Four types of biflavonoids from S. doederleinii, including IC3′–IIC8′′, IC3′–IIC6′′, IC3′–IIC3′′′, and C–O linked biflavonoids were examined originally using QTOF MS/MS. The fragmentation behavior of IC3′–IIC3′′′ linked biflavonoids was reported for the first time. A total of twenty biflavonoids were identified or tentatively characterized and eight biflavonoids were found from S. doederleinii for the first time. Furthermore, the 3-(4,5-Dimethyl-2-thizolyl)-2,5-diphenyltertazolium bromide (MTT) assay and xenograft model of mouse lewis lung cancer(LLC) in male C57BL/6 mice revealed favorable anticancer properties of the total biflavonoids extracts from S. doederleinii. The results of this work could provide useful knowledge for the identification of biflavonoids in herbal samples and further insights into the chemopreventive function of this plant.

Selaginella uncinata flavonoids ameliorated ovalbumin-induced airway inflammation in a rat model of asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Selaginella uncinata (Desv.) Spring, known as "Cuiyuncao", is a perennial herb widely distributed in the Southeast Asian countries. In the folk medicine, the local minority commonly use it to treat cough and asthma for centuries.

AIM OF THE STUDY

This study was carried out to investigate the protective mechanisms of total flavonoids from S. uncinata (SUF) on airway hyperresponsiveness, cytokine release and bitter taste receptors (T2Rs) signaling with emphasis on inflammatory responses in a rat model of ovalbumin (OVA)-induced asthma.

MATERIALS AND METHODS

Rats were sensitized and challenged with OVA to induce typical asthmatic reactions. Pathological changes of lung tissue were examined by HE staining. The serum levels of T cell-associated cytokines (IFN-γ, IL-4, IL-5 and IL-13), total IgE and OVA-specific IgE were determined by enzyme-linked immunosorbent assay (ELISA). Gene expressions of T2R10, IP3R1 and Orai1 in lung tissue were assayed by fluorescence quantitative real-time polymerase chain reaction (FQ-PCR) while protein expressions of NFAT1 and c-Myc were assayed by western blot analysis. The activation of SUF was investigated on tansgentic T2R10-GFP HEK293 cells.

RESULTS

SUF treatment attenuated airway hyperresponsiveness and goblet cell hyperplasia compared with OVA-challenged asthmatic rats. The serum levels of IL-4, IL-5 and IL-13 as well as total and OVA-specific IgE were decreased while serum IFN-γ was increased in SUF-treated rats. SUF treatment significantly up-regulated T2R10 gene expression, down-regulated IP3R1 and Orai1 gene expression. SUF further suppressed eotaxin, NFAT1 and c-Myc protein expression in lung tissues of OVA-challenged rats.

CONCLUSIONS

These results imply that SUF exerts anti-inflammatory function through the T2R10/IP3R1/NFAT1 dependent signaling pathway, and may warrant further evaluation as a possible agent for the treatment of asthma.

Ethyl acetate extract from Selaginella doederleinii Hieron inhibits the growth of human lung cancer cells A549 via caspase-dependent apoptosis pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Selaginella doederleinii Hieron has been used as a folk medicine for the treatment of different cancers, especially for nasopharyngeal carcinoma, lung cancer and trophoblastic tumor in China. Previously, the ethyl acetate extract from S. doederleinii (SDEA extract) showed favorable anti-cancer potentials. However, the main chemical composition and anticancer mechanism of the SDEA extract were still not very clear. Until now, there are no reports available about the oral toxicity of the extract.

AIM OF STUDY

The present study was to further elucidate the chemical composition and anti-lung cancer mechanism of the SDEA extract, and evaluate the acute oral toxicity of the extract.

MATERIALS AND METHODS

The SDEA extract was separated and analysed by HPLC to disclose its main chemicals. The effects of the extract were then investigated in vitro on cell viability, apoptosis and cell cycle using fluorescence microscopy and flow cytometry, and the molecular mechanism against human lung cancer cells A549 was further studied by western blot assays. The in vivo anti-cancer effect of the extract was evaluated in A549 xenograft mice model by histochemical assay, and tumor growth, microvascular density (MVD) and Ki67 expression were also measured. In addition, acute oral toxicity test of the extract was executed in mice.

RESULTS

SDEA extract mainly contained eight biflavonoids. The extract caused the loss of mitochondrial membrane potential and induced cell apoptosis by upregulating Bax, downregulating Bcl-2, activating caspase-9 and caspase-3 and blocked the cell cycle in S phase. The extract reduced expression of antigen Ki67, decreased MVD, and significantly inhibited the tumor growth. The extract did not show apparent oral acute toxicity in healthy mice.

CONCLUSION

The SDEA extract exerted anti-tumor effect through activating mitochondrial pathways and reducing Ki67 expression and MVD. Low oral acute toxicity suggested it a promising chemotherapy agent.

Antitumor Activities of Ethyl Acetate Extracts from Selaginella doederleinii Hieron In Vitro and In Vivo and Its Possible Mechanism

The antitumor activities of ethyl acetate extracts from Selaginella doederleinii Hieron (SD extracts) in vitro and in vivo and its possible mechanism were investigated. HPLC method was developed for chemical analysis. SD extracts were submitted to 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay on different cells, flow cytometry, and RT-PCR analysis using HepG2 cell and antitumor activity in vivo using H-22 xenograft tumor mice. Six biflavonoids from SD extracts were submitted to molecular docking assay. The results showed that SD extracts had considerable antitumor activity in vitro and in vivo without obvious toxicity on normal cells and could induce cell apoptosis. The mechanisms of tumorigenesis and cell apoptosis induced by SD extracts may be associated with decreasing the ratio of bcl-2 and bax mRNA level, activating caspase-3, suppressing survivin, and decreasing the gene expression of COX-2, 5-LOX, FLAP, and 12-LOX mRNA. The main active component in SD extracts is biflavonoids and some exhibited strong interactions with COX-2, 5-LOX, 12-LOX, and 15-LOX. These results offering evidence of possible mechanisms of SD extracts suppress cell proliferation and promote apoptosis and provide the molecular theoretical basis of clinical application of S. doederleinii for cancer therapy.