Med-Chemist : "Quintessential Medicinal Chemistry"
Wednesday, December 25, 2013
Toxin produced by bacteria could serve as model for next-generation antibiotics
The recent rise in antibiotic-resistant bacteria is a serious public health threat, and there is a need for new therapeutic strategies to combat these infections. A study published by Cell Press on November 14th in the journal Molecular Cell has revealed a new toxin that inhibits bacterial growth by blocking the DNA replication machinery, which is not targeted by currently available antibiotics. The findings open new therapeutic avenues for developing the next generation of antibiotics.
"One source of inspiration for new antibiotic targets is bacteria themselves," says senior study author Michael Laub of the Massachusetts Institute of Technology. "By studying the ways in which toxins produced by bacteria inhibit their growth, we may potentially find clues into targets that hadn't been considered previously."
Bacterial growth is regulated in part by sets of genes known as toxin-antitoxin (TA) systems, each of which typically encodes two proteins the toxin and the antitoxin. These proteins normally form a non-toxic complex, but under stressful conditions, the antitoxin degrades and frees up the toxin, which then inhibits bacterial proliferation. Despite the key role TA systems play in regulating bacterial growth, relatively little is known about how they work, and they currently are not targeted by any antibiotics in clinical use.
In the new study, Laub and his team identified a novel TA system called SocAB. Unlike all other known TA systems, SocAB targets bacterial DNA replication machinery. The toxin, SocB, blocks DNA replication and inhibits bacterial growth by interacting with a protein called DnaN, a central hub in protein networks involved in multiple cellular processes. The researchers also pinpointed the region on DnaN that is critical for this interaction. The findings suggest that novel antibiotics that mimic the effects of SocB by targeting this region on DnaN could form the basis of a promising therapeutic strategy in the future.
"Our results reveal unexpected diversity in the molecular mechanisms underlying toxin-antitoxin systems, which are found throughout the bacterial kingdom," Laub says. "Because DnaN is highly conserved between bacteria, targeting this part of the DNA replication machinery may be a generalizable strategy to inhibit bacterial growth."
Tuesday, December 24, 2013
Bitter melon extract may have potential to fight head, neck cancer
Extract taken from an Asian vegetable may have therapeutic qualities to treat head and neck cancer, a Saint Louis University researcher has found. Preliminary findings of the research were published in the Public Library of Science One Journal by Ratna Ray, Ph.D. associate professor of pathology at Saint Louis University. Ray found that bitter melon extract, a vegetable commonly used in Indian and Chinese diets, reduces the head and neck cancer cell growth in the animal model.
"We wanted to see the effect of the bitter melon extract treatment on different types of cancer using different model systems," said Ray, who first tested the extract in breast and prostate cancer cells. "In this study, the bitter melon extract treatment suppressed the head and neck cancer cell growth in the mouse model, reducing the growth of the tumor."
In a controlled lab setting, Ray found that bitter melon extract regulated several pathways that helped reduce the head and neck cancer cell growth in the animal model. After a period of four weeks, Ray found that the growth and volume of the tumor had reduced.
Bitter melon is a tropical vegetable that is commonly used in Indian and Chinese cooking. Ray, who is originally from India, often uses bitter melon in her meals. People in Asia use this vegetable in stir fries, salads, and also drink its juice as part of a healthy diet.
Although more research is needed, Ray believes the bitter melon extract may enhance the current treatment option.
"It's difficult to measure the exact impact of bitter melon extract treatment on the cell growth, but a combination of things -- existing drug therapy along with bitter melon may help the efficacy of the overall cancer treatment," Ray said.
Head and neck cancers, which account for 6 percent of all cancer cases, start in the mouth, nose, sinuses, voicebox and throat. They frequently are aggressive, and often spread from one part of the head or neck to another.
Before moving to phase I clinical trial with head and neck cancer patients, Ray said she and her team would need to validate their results with other preclinical models.
Ray's initial research found that treatment with this natural substance halted the breast and prostate cancer cell growth, eventually stopping them from spreading.
Monday, December 23, 2013
University of Sydney researchers identify new type of medication for osteoporosis
University of Sydney researchers have discovered a new and promising treatment for osteoporosis which is easily delivered in water soluble form.
After more than four years of investigation, researchers from the Ageing Bone Research Program (Sydney Medical School’s Nepean campus), have found the treatment has shown very promising results in animal experiments.
The compound is called picolinic acid, a product derived of the essential amino acid tryptophan.
Lead researcher Professor Gustavo Duque said the odorless compound can be easily dissolved in water.
“This is a major step in the development of a completely new type of medication for osteoporosis,” he said.
“Instead of stopping bone destruction, our compound instead stimulates bone formation."
“The product is easily dissolved in water, has a higher level of absorption and did not induce any side effects in the treated mice."
“When this medication was administered in the water of normal and menopausal mice, picolinic acid strongly and safely increased bone mass in normal mice and rescued bone from menopause-associated osteoporosis.”
Professor Duque said the team had patented the compound and will expand their trials to humans in the near future in a bid to address the increasing numbers of people developing the condition.
“Osteoporosis affects an estimated 300 million people worldwide. One in three women over 50 will experience osteoporotic fractures, as will one in five men."
Friday, December 20, 2013
Repurposed drug may be first targeted treatment for serious kidney disease
A drug approved for the treatment of rheumatoid arthritis may also turn out to be the first targeted therapy for one of the most common forms of kidney disease, a condition that almost inevitably leads to kidney failure. A team led by Massachusetts General Hospital (MGH) researchers is reporting that treatment with abatacept (Orencia) appeared to halt the course of focal segmental glomerulosclerosis (FSGS) in five patients, preventing four from losing transplanted kidneys and achieving disease remission in the fifth. The report is being issued online in the New England Journal of Medicine to coincide with a presentation at the American Society for Nephrology annual meeting.
Wednesday, December 18, 2013
Drug may guard against periodontitis, related chronic diseases
A drug currently used to treat intestinal worms could protect people from periodontitis, an advanced gum disease, which untreated can erode the structures including bone that hold the teeth in the jaw. The research was published ahead of print in Antimicrobial Agents and Chemotherapy. Current treatment for periodontitis involves scraping dental plaque, which is a polymicrobial biofilm, off of the root of the tooth. Despite this unpleasant and costly ordeal, the biofilm frequently grows back. But the investigators showed in an animal model of periodontitis that the drug Oxantel inhibits this growth by interfering with an enzyme that bacteria require for biofilm formation, says corresponding author Eric Reynolds, of the University of Melbourne, Australia. It does so in a dose-dependent manner, indicating efficacy.
The researchers began their search for a therapy for periodontitis by studying the symbioses of the periodontal pathogens, using genomics, proteomics, and metabolomics, in animal models of periodontitis. They soon found that the periodontal biofilm depended for growth on the availability of iron and heme (an iron-containing molecule related to hemoglobin), and that restricting these reduced levels of the enzyme, fumarate reductase. Since Oxantel (see structure) was known to inhibit fumarate reductase in some bacteria, they then successfully tested its ability to inhibit fumarate reductase activity in Porphyromonas gingivalis, one of the major bacterial components of periodontitis biofilms. Fumarate reductase is absent from humans, making it an ideal drug target.
They also showed that Oxantel disrupted the growth of polymicrobial biofilms containing P. gingivalis, Tannerella forsythia, and Treponema denticola, a typical composition of periodontal biofilms, despite the fact that the latter alone is unaffected by Oxantel.
The researchers found that treatment with Oxantel downregulated six P. gingivalis gene products, and upregulated 22 gene products, all of which are part of a regulon (a genetic unit) that controls availability of heme.
Periodontitis affects an estimated 30-47 percent of the adult population with severe forms affecting 5-10 percent. It also increases the risks of diabetes, heart disease, stroke, arthritis, and dementia, says Reynolds. These risks arise due to the pathogenic bacteria that enter the blood stream from periodontitis, as well as from the chronic inflammation caused by this disease, he says. Additionally, periodontitis correlates with increased risk of cancers of the head and neck, the esophagus, the tongue, and the pancreas, the investigators report.
Tuesday, December 17, 2013
Peptide derived from cow's milk kills human stomach cancer cells in culture
New research from a team of researchers in Taiwan indicates that a peptide fragment derived from cow's milk, known as lactoferricin B25 (LFcinB25), exhibited potent anticancer capability against human stomach cancer cell cultures. The findings, published in the Journal of Dairy Science®, provide support for future use of LFcinB25 as a potential therapeutic agent for gastric cancer.
"Gastric cancer is one of the most common causes of cancer-related mortality worldwide, especially in Asian countries," says Wei-Jung Chen, PhD, of the Department of Biotechnology and Animal Science of National Ilan University, Taiwan Republic of China. "In general, the main curative therapies for gastric cancer are surgery and chemotherapy, which are generally only successful if the cancer is diagnosed at an early stage. Novel treatment strategies to improve prognosis are urgently needed."
Investigators evaluated the effects of three peptide fragments derived from lactoferricin B, a peptide in milk that has antimicrobial properties. Only one of the fragments, LFcinB25 reduced the survival of human AGS (Gastric Adenocarcinoma) cells in a dose-dependent and time-dependent manner.
Under a microscope the investigators could see that after an hour of exposure to the gastric cancer cells, LFcinB25 migrated to the cell membrane of the AGS cells, and within 24 hours the cancer cells had shrunken in size and lost their ability to adhere to surfaces. In the early stages of exposure, LFcinB25 reduced cell viability through both apoptosis (programmed cell death) and autophagy (degradation and recycling of obsolete or damaged cell parts). At later stages, apoptosis appeared to dominate, possibly through caspase-dependent mechanisms, and autophagy waned.
"This is the first report describing interplay between apoptosis and autophagy in LFcinB-induced cell death of cancer cells," says Dr. Chen.
Monday, December 16, 2013
New antifungal composition effectively inhibits wide variety of fungi
In order to overcome resistance to antifungal variety of pathogenic fungi and yeast, researchers from the University of Alicante have developed a novel and efficient antifungal composition with pharmacological applications in agriculture and food industry, among others.
The composition, developed and patented by the UA Research Group in Plant Pathology, is based on the combined use of chitosan, or chitosan oligosaccharides (right structure, COS), antifungal agents and additives that synergistically affect the growth of a variety of pathogenic fungi.
"Chitosan is a non-toxic biopolymer, biocompatible and naturally degradable, with antibacterial, antiviral and antifungal properties obtained from chitin, the main constituent of hard body parts of invertebrates, such as the shells of shrimp, lobsters, crabs, and other marine crustaceans, and is part of the fungal cell wall," as explained by lecturer Luis Vicente López Llorca, Director of the UA Research Group in Plant Pathology and head of the research work.
"Because many fungal pathogens develop resistance to prolonged treatment with antifungal drugs, it is desirable to find alternatives for their control in medical, agricultural and those applications in which the fungi cause damage. In clinics, pathogenic fungi resistant to antifungal drugs are a major cause of mortality in patients. Chitosan and the antifungal additives, some based on the identification of molecular targets of chitosan, contribute to produce a novel alternative to control fungal diseases and in particular antifungal resistant strains" López Llorca said.
The various experiments carried out by the research group are proof of the significant synergistic effect of the combination of chitosan (or COS) and other antifungals and ARL1 gene inhibitor, in inhibiting the growth of mold and yeast . "Chitosan is nontoxic to mammals, making it suitable for use as an antifungal in various applications," LuÃs Vicente López adds.
Friday, December 13, 2013
First in-human trial of endoxifen shows promise as breast cancer treatment
Estrogen receptor α (ERα) ligand; potent antiestrogen. Metabolite of tamoxifen (Cat. No. 0999). Primary metabolite responsible for the effectiveness of tamoxifen in ER-positive breast cancer...
Compound in grapes, red wine could help treat multiple types of cancer
In continuation of my update on resveratrol
A recent study by a University of Missouri researcher shows that resveratrol, a compound found in grape skins and red wine, can make certain tumor cells more susceptible to radiation treatment. This research, which studied melanoma cells, follows a previous MU study that found similar results in the treatment of prostate cancer. The next step is for researchers to develop a successful method to deliver the compound to tumor sites and potentially treat many types of cancers.
"Our study investigated how resveratrol and radiotherapy inhibit the survival of melanoma cells," said Michael Nicholl, MD, assistant professor of surgery at the MU School of Medicine and surgical oncologist at Ellis Fischel Cancer Center in Columbia, Mo. "This work expands upon our previous success with resveratrol and radiation in prostate cancer. Because of difficulties involved in delivery of adequate amounts of resveratrol to melanoma tumors, the compound is probably not an effective treatment for advanced melanoma at this time."
The study found that melanoma cells become more susceptible to radiation if they were treated first with resveratrol. The MU researcher found that when the cancer was treated with resveratrol alone, 44 percent of the tumor cells were killed. When the cancer cells were treated with a combination of both resveratrol and radiation, 65 percent of the tumor cells died.
Nicholl said his findings could lead to more research into the cancer-fighting benefits of the naturally occurring compound.
"We've seen glimmers of possibilities, and it seems that resveratrol could potentially be very important in treating a variety of cancers," Nicholl said. "It comes down to how to administer the resveratrol. If we can develop a successful way to deliver the compound to tumor sites, resveratrol could potentially be used to treat many types of cancers. Melanoma is very tricky due to the nature of how the cancer cells travel throughout the body, but we envision resveratrol could be combined with radiation to treat symptomatic metastatic tumors, which can develop in the brain or bone."Ref : http://dx.doi.org/10.1016/j.jss.2013.02.037
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