Synergistic effect of three benzopyrans isolated from Hypericum polyanthemum in U-373 MG glioblastoma cell line

Bioassay-guided isolation of active substances from Semen Torreyae identifies two new anthelmintic compounds with novel mechanism of action

ETHNOPHARMACOLOGICAL RELEVANCE

Semen Torreyae, the seeds of Torreya grandis Fortune ex Lindley (Cephalotaxaceae) is a well-known traditional Chinese medicinal plant recorded in the Chinese Pharmacopeia (2010 version). It is widely used for treating intestinal parasites in China, owing to its desirable efficacy and safety. However, the anthelmintic compounds in Semen Torreyae have not yet been identified.

AIM OF THE STUDY

This study aims to identify the compounds active against helminths from Semen Torreyae. In addition, we tested whether C. elegans strains resistant to currently-used anthelmintic drugs showed cross-resistance to these compounds.

METHODS

A bioassay-guided isolation of anthelmintic compounds from Semen Torreyae was performed using a Caenorhabditis elegans (C. elegans) testing model. The structures of active compounds were elucidated by a combination of GC-MS, high resolution MS, and NMR. The median-effect method was employed to generate a combination index (CI) to evaluate the synergistic effect of the anthelmintic compounds. A panel of C. elegans mutant strains resistant against the major anthelmintic drug classes was used to study the cross-resistance to currently-used anthelmintic drugs. A panel of transient receptor potential (TRP) channel mutant strains was also tested to explore the possible mechanisms of action of the anthelmintic compounds.

RESULTS

The bioassay-guided isolation led to two active compounds, i.e. galangal acetate (IC₅₀: 58.5 ± 8.9 μM) and miogadial (IC₅₀: 25.1 ± 5.4 μM). The combination of galangal acetate and miogadial resulted in a synergistic effect at IC₅₀, IC₇₀, and IC₉₀ levels (CIs < 1). Galangal acetate and miogadial demonstrated similar activity against drug-resistant C. elegans strains compared to the wild-type strain. In addition, none of the TRP mutants was significantly resistant to galangal acetate or miogadial compared to wild type worms.

CONCLUSIONS

We identified the bioactive compounds from Semen Torreyae responsible for its anthelmintic activity: galangal acetate and miogadial. The two anthelmintic compounds demonstrated a synergistic effect against C. elegans. Galangal acetate and miogadial are unlikely to act on the targets of currently-used anthelmintics (ivermectin, levamisole, benomyl and aldicarb), and an action on TRP channels appears to be ruled out as well. In summary, galangal acetate and miogadial are promising anthelmintic hits worth further investigation.

Evaluation of the cytotoxic activity of Hypericum spp. on human glioblastoma A1235 and breast cancer MDA MB-231 cells

Cytotoxic activity of 16 Hypericum ethanolic extracts was evaluated by MTT assay on two human cancer cell lines: glioblastoma A1235 and breast cancer MDA MB-231. Morphology and the type of induced cell death were determined using light and fluorescence microscopy. The majority of Hypericum extracts had no significant cytotoxic effect on MDA MB-231 cells. Eight extracts exhibited mild cytotoxic effect on A1235 cells after 24 h incubation, ranging from 8.0% (H. patulum) to 21.7% (H. oblongifolium). After 72 h of treatment, the strongest inhibition of A1235 viability was observed for extracts of H. androsaemum (26.4-43.9%), H. balearicum (25.8-36.3%), H. delphicum (14.8-27.4%) and H. densiflorum (11.2-24.1%). Micro-scopic examination of cells showed apoptosis as the dominant type of cell death. Due to observed high viability of treated cells, we propose that cytotoxic effects of Hypericum extracts could be related to alternations/interruptions in the cell cycle.

Anti-ageing active ingredients from herbs and nutraceuticals used in traditional Chinese medicine: pharmacological mechanisms and implications for drug discovery

Ageing, an unanswered question in the medical field, is a multifactorial process that results in a progressive functional decline in cells, tissues and organisms. Although it is impossible to prevent ageing, slowing down the rate of ageing is entirely possible to achieve. Traditional Chinese medicine (TCM) is characterized by the nourishing of life and its role in anti-ageing is getting more and more attention. This article summarizes the work done on the natural products from TCM that are reported to have anti-ageing effects, in the past two decades. The effective anti-ageing ingredients identified can be generally divided into flavonoids, saponins, polysaccharides, alkaloids and others. Astragaloside, Cistanche tubulosa acteoside, icariin, tetrahydrocurcumin, quercetin, butein, berberine, catechin, curcumin, epigallocatechin gallate, gastrodin, 6-Gingerol, glaucarubinone, ginsenoside Rg1, luteolin, icarisid II, naringenin, resveratrol, theaflavin, carnosic acid, catalpol, chrysophanol, cycloastragenol, emodin, galangin, echinacoside, ferulic acid, huperzine, honokiol, isoliensinine, phycocyanin, proanthocyanidins, rosmarinic acid, oxymatrine, piceid, puerarin and salvianolic acid B are specified in this review. Simultaneously, chemical structures of the monomers with anti-ageing activities are listed, and their source, model, efficacy and mechanism are also described. The TCMs with anti-ageing function are classified according to their action pathways, including the telomere and telomerase, the sirtuins, the mammalian target of rapamycin, AMP-activated kinase and insulin/insulin-like growth factor-1 signalling pathway, free radicals scavenging and the resistance to DNA damage. Finally, Chinese compound prescription and extracts related to anti-ageing are introduced, which provides the basis and the direction for the further development of novel and potential drugs.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Leishmanicidal activity of lipophilic extracts of some Hypericum species

Leishmaniasis has emerged as the third most prevalent parasite-borne disease worldwide after malaria and filariasis, with about 350 million people at risk of infection. Antileishmanial drugs currently available have various limitations, mainly because of the parasite resistance and side effects. The search of new antileishmanial drugs is ventured throughout the world.

PURPOSE

The purpose of this study was to assess the leishmanicidal activity of lipophilic extracts of eight Hypericum species against promastigote forms of Leishmania (Leishmania) amazonensis.

MATERIAL AND METHODS

The dried and powered materials of aerial parts of H. andinum Gleason, H. brevistylum Choisy, H. caprifoliatum Cham. & Schltdl., H. carinatum Griseb., H. linoides A. St.-Hil., H. myrianthum Cham. & Schltdl., H. polyanthemum Klotzsch ex Reichardt and H. silenoides Juss. were extracted by static maceration with n-hexane. Extracts were evaporated to dryness under reduced pressure and stored at -20°C until biological evaluation and HPLC analysis. The metabolites investigated were dimeric phloroglucinol derivatives, benzophenones and benzopyrans. The yields were expressed as mean of three injections in mg of compound per g of extract (mg/g extract). The effect of Hypericum species on the viability of infective forms of L. (L.) amazonensis was determined using a hemocytometer. Amphotericin B was used as a standard drug. The 50% inhibitory concentration (IC50) values for each extract were determined by linear regression analysis. The cytotoxic effects of extracts were assessed on peritoneal macrophages of BALB/c mice by MTT assay. The concentration that causes 50% of macrophage cytotoxicity (CC50) was determined by linear regression analysis. The selectivity index (SI) of the extracts was determined considering the following equation: CC50 against mammalian cells/IC50 against L. amazonensis.

RESULTS

We demonstrated that H. carinatum, H. linoides and H. polyanthemum were able to kill the parasites in a dose dependent manner. These extracts presented low cytotoxicity against murine macrophages. At 48h of incubation H. polyanthemum presented significant leishmanicidal activity with a 50% inhibitory concentration (IC50) of 36.1µg/ml. The leishmanicidal activity of H. myrianthum was significantly lower than that presented by H. polyanthemum, H. carinatum and H. linoides extracts. H. brevistylum and H. caprifoliatum showed significant leishmanicidal activity only at high concentrations (500 and 1000µg/ml), while H. andinum and H. silenoides were ineffective.

CONCLUSION

The promising results demonstrate the importance of the species of the genus Hypericum as source of compounds potentially useful for the treatment of leishmaniasis.

Potentiating therapeutic effects by enhancing synergism based on active constituents from traditional medicine

Shifting current drug discovery tide from 'finding new drugs' to 'screening natural products' may be helpful for overcoming the 'more investment, fewer drugs' challenge. Traditional Chinese medicine (TCM), relying on natural products, has been playing a very important role in health protection and disease control for thousands of years in Asia, whose therapeutic efficacy is based on the 'synergism', that is, the combinational effects to be greater than that of the individual drug. Based on syndromes and patient characteristics and guided by the theories of TCM, formulae are designed to contain a combination of various kinds of crude drugs that, when combined, generally assume that a synergism of all ingredients will bring about the maximum of therapeutic efficacy. The increasing evidence has shown that multiple active component combinations of TCM could amplify the therapeutic efficacy of each agent, representing a new trend for modern medicine. However, the precise mechanism of synergistic action remains poorly understood. The present review highlights the concept of synergy and gives some examples of synergistic effects of TCM, and provides an overview of the recent and potential developments of advancing drug discovery towards more agile development of targeted combination therapies from TCM.