Tuesday, September 15, 2020

New insecticide compounds from plant used for traditional Chinese medicine

For hundreds of years, practitioners of traditional Chinese medicine have used an herb called Stemona sessilifolia as a remedy for parasitic infections, such as those caused by pinworms and lice. Now, researchers reporting in ACS' Journal of Agricultural and Food Chemistry have identified 10 compounds that might be responsible for the herb's effectiveness. But there's a twist: The insecticides are produced by symbiotic microbes that live within the plant's cells -; not by S. sessilifolia itself.
Stemona curtisii CBM.png
Endophytes are microorganisms that live inside plant cells but do not cause apparent disease. Instead, some endophytes help plants survive by enhancing growth, nutrient acquisition, or resistance to drought or pests. Therefore, scientists are investigating endophytes as potential sources of new medicines and agrichemicals. Xiachang Wang, Lihong Hu and colleagues wanted to screen endophytes from S. sessilifolia for insecticidal activity.
To isolate endophytes, the researchers spread fresh, cut-up pieces of S. sessilifolia on agar plates. They then collected the bacteria that grew on the plates, analyzed the DNA and identified the microbes as Streptomyces clavuligerus. Using nuclear magnetic resonance spectroscopy and mass spectrometry, the team purified 10 new compounds from the bacteria with structures similar to a class of insecticides known as pyrroles. Testing the substances on insects revealed that they were strongly toxic to aphids and moderately toxic to spider mites. A bacterial extract containing all of the compounds had greater lethal activity than any compound alone. These substances, or the bacteria that produce them, could be promising new natural pesticides, the researchers say.
The authors acknowledge funding from the National Key R&D Program, the Nature Science Foundation of Jiangsu Higher Education Institutions of China, the Outstanding Scientific and Technological Innovation Team Program of Jiangsu Higher Education Institutions, Jiangsu Provincial "Double Creation Program" and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

Saturday, September 12, 2020

Combined drug treatment for lung cancer and secondary tumors

In continuation of my update on alectiniberlotinib and  osimertinib

Alectinib structure.svg 

                                                   Erlotinib Structural Formulae.png 

Researchers at Kanazawa University report in the Journal of Thoracic Oncology a promising novel approach for a combined treatment of the most common type of lung cancer and associated secondary cancers in the central nervous system. The approach lies in combining two cancer drugs, with one compensating for a resistance side effect of the other.

In 20 to 40% of patients with cancer, metastasis (the development of secondary tumors) in the central nervous system (CNS) occurs. CNS metastasis impacts negatively on a patient's quality of life, and is associated with a poor health prognosis. In a form of cancer known as ALK-rearranged non-small-cell lung cancer (NSCLC), CNS metastasis is known to persist when drugs targeting primary tumors are used. Now, Seiji Yano from Kanazawa University and colleagues have investigated the origins for the resistence to such drugs, and tested a new therapeutic strategy on a mouse model.

The researchers looked at the drug alectinib. Although used in standard treatments for advanced ALK-rearranged NSCLC, approximately 20 to 30% of patients treated with alectinib develop CNS metastasis, which is attributed to acquired resistance to the drug.
By treating mice first injected with tumor cells with alectinib daily for 16 weeks, the scientists obtained a mouse model displaying alectinib resistance. By biochemical analyses of the mouse brains, Yano and colleagues were able to link the resistance to the activation of a protein known as epidermal growth factor receptor (EGFR). This activation is, in turn, a result of an increase in production of amphiregulin (AREG), a protein that binds to EGFR and in doing so 'activates' it.
Based on this insight, the researchers tested the effect of administering drugs used for inhibiting the action of EGFR in combination with alectinib treatment. The experiments showed that a combination treatment of alctinib with either erlotinib or osimertinib—two existing EGFR-inibiting drugs—prevented the progression of CNS metastasis, controlling the condition for over 30 days.
The scientists conclude that the combined use of alectinib and EGFR-inhibitors could overcome alectinib resistance in the mouse model of leptomeningeal carcinomatosis (LMC), a particular type of CNS metastasis. Quoting Yano and colleagues: "Our findings may provide rationale for clinical trials to investigate the effects of novel therapies dual-targeting ALK and EGFR in ALK-rearranged NSCLC with alectinib-resistant LMC."
Non-small-cell lung cancer
Non-small-cell lung carcinoma (NSCLC) and small-cell lung carcinoma (SCLC) are the two types of lung cancer. 85% of all lung cancers are of the NSCLC type. NSCLCs are less sensitive to chemotherapy than SCLCs, making drug treatment of the highest importance.
Alectinib is a drug used for treating NSCLC, with good efficiency. However, 20-30% of patients taking the  develop secondary cancer in the central nervous system (CNS), which is associated with an acquired resistance to alectinib. Seiji Yano from Kanazawa University and colleagues have now made progress towards a novel therapy against this resistance: a combination of alectinib with other drugs.
Epidermal growth factor receptor inhibitors
The drugs that Yano and colleagues tested in combination with alectinib on a mouse model were of a type known as epidermal growth factor receptor (EGFR) inhibitors, including osimertinib and erlotinib. Both are being used as medication for treating NSCLC. The former was approved in 2017 as cancer treatment by the U.S. Food and Drug Administration and the European Commission. Yano and colleagues obtained results showing that EGFR inhibitors counteract resistance to alectinib and have therefore potential in novel therapies for NSCLC and secondary cancers in the CNS.

Tuesday, September 8, 2020

Nourianz Approved to Treat 'Off' Episodes in Parkinson Disease

In continuation of my update on Levodopa 
Nourianz (istradefylline) tablets have been approved as an add-on treatment to levodopa/carbidopa for adults with Parkinson disease experiencing "off" episodes, the U.S. Food and Drug Administration announced yesterday.
The drug is available in 20-mg or 40-mg doses, but the maximum recommended dosage in patients taking CYP3A4 inhibitors and those with moderate hepatic impairment is 20 mg once daily. The safety information for Nourianz states that use of the drug should be avoided in these patient populations.
Data from four 12-week placebo-controlled clinical studies demonstrated the effectiveness of Nourianz, a selective adenosine A2A receptor antagonist, in treating "off" episodes in 1,143 PD patients who were receiving treatment with levodopa/carbidopa. Compared with patients who received placebo, patients who received Nourianz experienced a statistically significant decrease in daily "off" time from baseline.
The most commonly reported adverse reactions with Nourianz included dyskinesia, dizziness, constipation, nausea, hallucination, and insomnia. The FDA noted that physicians should monitor patients for the development or progression of dyskinesia while taking Nourianz. A reduction in dosage or stoppage of Nourianz should be considered in the case of hallucinations, psychotic behavior, or impulsive/compulsive behavior. Nourianz should not be used during pregnancy, and women with childbearing potential should use contraception during treatment.
https://pubchem.ncbi.nlm.nih.gov/compound/Istradefylline#section=2D-Structure          https://en.wikipedia.org/wiki/Istradefylline