New limonophyllines A-C from the stem of Atalantia monophylla and cytotoxicity against cholangiocarcinoma and HepG2 cell lines

The Role of Herbal Medicine in Cholangiocarcinoma Control: A Systematic Review

The growing incidence of cholangiocarcinoma (bile duct cancer) and limited treatment options stimulate a pressing demand for research and the development of new chemotherapeutics against cholangiocarcinoma. This study aimed to systematically review herbs and herb-derived compounds or herbal formulations that have been investigated for their anti-cholangiocarcinoma potential. Systematic literature searches were conducted in three electronic databases: PubMed, ScienceDirect, and Scopus. One hundred and twenty-three research articles fulfilled the eligibility critera and were included in the analysis (68 herbs, isolated compounds and/or synthetic analogs, 9 herbal formulations, and 119 compounds that are commonly found in several plant species). The most investigated herbs were Atractylodes lancea (Thunb.) DC. (Compositae) and Curcuma longa L. (Zingiberaceae). Only A. lancea (Thunb.) DC. (Compositae) has undergone the full process of nonclinical and clinical development to deliver the final product for clinical use. The extracts of A. lancea (Thunb.) DC. (Compositae), Garcinia hanburyi Hook.f. (Clusiaceae), and Piper nigrum L. (Piperaceae) exhibit antiproliferative activities against human cholangiocarcinoma cells (IC₅₀ < 15 µg/mL). Cucurbitacin B and triptolide are herbal isolated compounds that exhibit the most promising activities (IC₅₀ < 1 µM). A series of experimental studies (in vitro, in vivo, and humans) confirmed the anti-cholangiocarcinoma potential and safety profile of A. lancea (Thunb.) DC. (Compositae) and its active compounds atractylodin and β-eudesmol, including the capsule pharmaceutical of the standardized A. lancea (Thunb.) DC. (Compositae) extract. Future research should be focused on the full development of the candidate herbs to deliver products that are safe and effective for cholangiocarcinoma control.

Acridone Derivatives from Atalantia monophyla Inhibited Cancer Cell Proliferation through ERK Pathway

The present study aimed to investigate the effect of acridone alkaloids on cancer cell lines and elucidate the underlying molecular mechanisms. The ten acridone alkaloids from Atalantia monophyla were screened for cytotoxicity against LNCaP cell lines by a WST-8 assay. Then, the most potential acridone, buxifoliadine E, was evaluated on four types of cancer cells, namely prostate cancer (LNCaP), neuroblastoma (SH SY5Y), hepatoblastoma (HepG2), and colorectal cancer (HT29). The results showed that buxifoliadine E was able to significantly inhibit the proliferation of all four types of cancer cells, having the most potent cytotoxicity against the HepG2 cell line. Western blotting analysis was performed to assess the expression of signaling proteins in the cancer cells. In HepG2 cells, buxifoliadine E induced changes in the levels of Bid as well as cleaved caspase-3 and Bax through MAPKs, including Erk and p38. Moreover, the binding interaction between buxifoliadine E and Erk was investigated by using the Autodock 4.2.6 and Discovery Studio programs. The result showed that buxifoliadine E bound at the ATP-binding site, located at the interface between the N- and C-terminal lobes of Erk2. The results of this study indicate that buxifoliadine E suppressed cancer cell proliferation by inhibiting the Erk pathway.

A comprehensive review on acridone based derivatives as future anti-cancer agents and their structure activity relationships

The development of drug resistance and severe side-effects has reduced the clinical efficacy of the existing anti-cancer drugs available in the market. Thus, there is always a constant need to develop newer anti-cancer drugs with minimal adverse effects. Researchers all over the world have been focusing on various alternative strategies to discover novel, potent, and target specific molecules for cancer therapy. In this direction, several heterocyclic compounds are being explored but amongst them one promising heterocycle is acridone which has attracted the attention of medicinal chemists and gained huge biological importance as acridones are found to act on different therapeutically proven molecular targets, overcome ABC transporters mediated drug resistance and DNA intercalation in cancer cells. Some of these acridone derivatives have reached clinical studies as these heterocycles have shown huge potential in cancer therapeutics and imaging. Here, the authors have attempted to compile and make some recommendations of acridone based derivatives concerning their cancer biological targets and in vitro-cytotoxicity based on drug design and novelty to increase their therapeutic potential. This review also provides some important insights on the design, receptor targeting and future directions for the development of acridones as possible clinically effective anti-cancer agents.

Assessment of antimycobacterial activities of pure compounds extracted from Thai medicinal plants against clarithromycin-resistant Mycobacterium abscessus

Background

Infection with Mycobacterium abscessus is usually chronic and is associated with clarithromycin resistance. Increasing drug resistance is a major public-health problem and has led to the search for new antimycobacterial agents. We evaluated the antimycobacterial activity, toxicity, and synergistic effects of several plant secondary metabolites against M. abscessus.

Methods

Twenty-three compounds were evaluated for antimycobacterial activity against thirty M. abscessus clinical isolates by broth microdilution to determine their minimum inhibitory concentration (MIC) values. Toxicity was evaluated using red and white blood cells (RBCs and WBCs). The compounds were used in combination with clarithromycin to investigate the possibility of synergistic activity.

Results

Five out of twenty-three compounds (RL008, RL009, RL011, RL012 and RL013) exhibited interesting antimycobacterial activity against M. abscessus, with MIC values ranging from <1 to >128 μg/mL. These extracts did not induce hemolytic effect on RBCs and displayed low toxicity against WBCs. The five least-toxic compounds were tested for synergism with clarithromycin against seven isolates with inducible clarithromycin resistance and seven with acquired clarithromycin resistance. The best synergistic results against these isolates were observed for RL008 and RL009 (8/14 isolates; 57%).

Conclusions

This study demonstrated antimycobacterial and synergistic activities of pure compounds extracted from medicinal plants against clarithromycin-resistant M. abscessus. This synergistic action, together with clarithromycin, may be effective for treating infections and should be further studied for the development of novel antimicrobial agents.

Multi-Target Actions of Acridones from Atalantia monophylla towards Alzheimer's Pathogenesis and Their Pharmacokinetic Properties

Ten acridones isolated from Atalantia monophylla were evaluated for effects on Alzheimer’s disease pathogenesis including antioxidant effects, acetylcholinesterase (AChE) inhibition, prevention of beta-amyloid (Aβ) aggregation and neuroprotection. To understand the mechanism, the type of AChE inhibition was investigated in vitro and binding interactions between acridones and AChE or Aβ were explored in silico. Drug-likeness and ADMET parameters were predicted in silico using SwissADME and pKCSM programs, respectively. All acridones showed favorable drug-likeness and possessed multifunctional activities targeting AChE function, Aβ aggregation and oxidation. All acridones inhibited AChE in a mixed-type manner and bound AChE at both catalytic anionic and peripheral anionic sites. In silico analysis showed that acridones interfered with Aβ aggregation by interacting at the central hydrophobic core, C-terminal hydrophobic region, and the key residues 41 and 42. Citrusinine II showed potent multifunctional action with the best ADMET profile and could alleviate neuronal cell damage induced by hydrogen peroxide and Aβ_1-42 toxicity.

Atalantiaphyllines A-G, prenylated acridones from Atalantia monophylla DC. and their aromatase inhibition and cytotoxic activities

Seven previously undescribed acridones, named atalantiaphyllines A-G, along with twenty-six known compounds were isolated from the dichloromethane extracts of roots and stems of Atalantia monophylla DC. Their structures were elucidated by analysis of extensive NMR and HRMS data. Aromatase inhibition, cytotoxicity against MOLT-3, HepG2, A549 and HuCCA-1 cell lines and DPPH radical scavenging activity of these compounds were evaluated. Most of the tested acridones exhibited higher potency in inhibiting aromatase than the positive control, ketoconazole, with IC₅₀ values in the range of 0.08-2.0 μM. In the cytotoxicity assay, cycloataphylline A, N-methylbuxifoliadine E and atalantiaphylline G were selectively cytotoxic against MOLT-3 cell line with IC₅₀ values of 8.0, 5.4 and 9.8 μM, respectively, while only atalaphyllidine exhibited highest antioxidant activity as evaluated by DPPH free radical scavenging assay with an IC₅₀ value of 22.4 μM.

Styrenes from the Seeds of Atalantia monophylla

Four new dimeric styrenes, 1-4, were isolated from an EtOAc crude extract of the seeds of Atalantia monophylla. The biosynthetic pathway of 1 is proposed to involve a [2 + 2] cycloaddition, while 2-4 may be generated via a polar mechanism with a carbocation as the key intermediate. The structures of 1-4 were defined from spectroscopic analysis; experimental and calculated ECD spectra were used to characterize their absolute configurations. When tested against two different cancer cell lines, 1-4 were not determined to be cytotoxic (IC₅₀ > 10 μM).