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Follow Antony Omita's research journey covering antibiotic resistance, diabetes treatment, and natural products for drug discovery. Explore challenges, current treatments, and innovative steps in drug development.
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From Antibiotics to Diabetes to Drug Delivery: My Journey in Research Thus Far Presented by Antony Omita 31st January 2018
9 IGCSE’s 4 Science A-Levels BSc Biochemistry MSc Drug discovery and development Currently doing a PhD in Drug delivery
Undergraduate Project: Antibiotic Resistance Image source: Perros, M. (2015), ‘A sustainable model for antibiotics’. Science. 347(6226):1062-64
Factors slowing down discovery and development of new antibiotics • High research costs - leading to decline in interest by the pharmaceutical industry • Technological limitations • It takes long to get approval from the various regulatory bodies for the drugs to make it to market • Attrition Factors leading to development of antibiotic resistance • Limited number of available antibiotics to use • Resistance had already been noted prior to drug introduction to the public for some antibiotics • Increased misuse of existing antibiotics leading to development of antibiotic resistance • Increased use of antibiotics in farming for treatment of animals
Steps being taken to improve rate of discovery and lower rate of development of antibiotic resistance • Financial incentives for pharmaceutical companies • Exploring new sources for antibiotics such as fungi, reptiles, oceans and marine life • Introduction of new high throughput technologies to help ease the research process • Educating the public on proper use of antibiotics • Introducing regulations and imposing penalties for improper prescription of antibiotics
Masters Project: Testing Antidiabetic Activity of Plants • Diabetes is characterised by increased blood glucose concentrations. There are different forms of diabetes, the common ones being type 1 and type 2 diabetes. • Type 2 diabetes occurs when tissues develop insulin resistance and there is impaired production and secretion of insulin from β-cells. • Type 2 diabetes accounts for 90% of cases of diabetes and it has also been found to be the cause of 5% of global deaths. • Obesity is the greatest risk factor for development of type 2 diabetes. Sedentary lifestyle and modern dietary habits are currently contributing to rising cases of obesity. • It is projected that the number of those suffering from diabetes will rise from the current 415 million to 642 million people by 2040. • Current estimates show that it costs the NHS £10 billion annually to treat cases of diabetes. Figure 1. Comparison of normal glucose absorption and glucose absorption when an individual is insulin resistant.
Current treatments for type 2 diabetes and their limitations • The first intervention is usually guided change in diet accompanied with increased physical activity. • In some cases, diet and physical activity need to be augmented with use of medications to help manage the glucose, lipid and blood pressure control abnormalities. • Metformin is currently the primary pharmaceutical option for treatment of type 2 diabetes; it improves insulin sensitivity. • The main limitation of current treatments is treatment inadequacies. This is because current therapies are limited by their mechanisms of action. They are limited because they target the symptoms caused by type 2 diabetes rather than the underlying root cause of the disease. Figure 2. Increased physical activity in combination with medical intervention is required for effective treatment of diabetes. Figure 3. Metformin. The current primary therapeutic option for treatment of type 2 diabetes.
Acetyl-CoA Carboxylase (ACC) Fatty Acid Triacylglycerol Fatty-Acyl CoA Glucose Fatty acid synthesis Lactate CPT-1 Malonyl-CoA Pyruvate Fatty-Acyl CoA Malonyl-CoA Fatty acid β-oxidation ACC 1 Acetyl-CoA ACC 2 Citrate Krebs Cycle Mitochondria Citrate Acetyl-CoA
Natural products in treatment of type 2 diabetes • Due to the broad diversity of compounds found in plants, natural products are a promising source for the discovery of novel compounds for inhibition of ACC 1 activity. • Studies performed on crude extracts from natural products have shown that a variety of them are able to cause inhibition of ACC 1 activity. Some examples of natural products that have been shown to inhibit ACC 1 activity include: • Green tea • Bitter melon • Avocado • This study used plants that are all commonly consumed. It is hoped that if the active compounds are obtained from plants that are usually consumed, their side effects will be minimal if any.
Methods Lactating rat mammary gland Affinity purification of ACC on avidin-sepharose column Plant Sample ACC Bioassay In vitro NaH14CO3 Acetyl-CoA Aqueous Extraction Plant extract ATP ACC 1 14C-Malonyl-CoA
Aims and Objectives • Indigenous Sri Lankan communities make use of traditional concoctions to treat type 2 diabetes. • This study therefore aimed to use five plants used in the traditional concoctions and test their antidiabetic potential by determining how sensitive ACC 1 was to inhibition by their crude extracts. • The five plant species studied were Achyranthes aspera (AA), Artocarpus heterophyllus (AH), Coccinia grandis (CG), Ipomoea aquatica (IA) and Mukia maderaspatana (MM). • In addition, garlic has been shown to have medicinal properties. This study therefore looked into the potential of both black and white garlic to give favourable antidiabetic effects based on their ability to inhibit ACC 1 activity. Figure 4. Black garlic bulbs. Black garlic is produced by ageing white garlic cloves at high temperature (70 °C) and high humidity. Figure 5. White garlic bulbs.
ACC 1 dose response when tested with Sri Lanka plant samples Figure 6. Dose response of ACC 1 when exposed to the five Sri Lanka sourced plant samples. Of the five plants tested by assay of ACC 1, it was CG that was the most potent inhibitor of ACC 1 activity (IC50=3.4 mg/ml) while AA was the least potent inhibitor (IC50=13.6 mg/ml).
ACC 1 dose response when tested with fresh and 12 month old garlic samples Figure 7. Dose response of ACC 1 when exposed to fresh black and white garlic extracts (Samples powdered before extract preparation). Black garlic was found to be a more potent inhibitor of ACC 1 activity compared to white garlic extract. Black garlic IC50 (21 mg/ml) and white garlic IC50 (77.50 mg/ml). Figure 8. Dose response of ACC 1 activity when exposed to 12 month old garlic samples (Samples not powdered before extract preparation). These results were the complete opposite of those obtained with fresh garlic extracts. In this case, white garlic extract was shown to be a more potent inhibitor of ACC 1 (IC50=12 mg/ml) compared to the black garlic extract (IC50=66 mg/ml).
ACC 1 dose response when tested with fresh garlic samples Figure 9. Dose response of ACC 1 when exposed to fresh black and white garlic extracts (Samples not powdered before extract preparation). Fresh black garlic was found to be a more potent inhibitor of ACC 1 activity compared to fresh white garlic. Fresh black garlic had an IC50 of 6 mg/ml while white garlic had an IC50 of 80 mg/ml. Figure 10. Dose response of ACC 1 when exposed to fresh black and white garlic extracts (Samples powdered before extract preparation). When extract was powdered before extract preparation, fresh black garlic was still found to be a more potent inhibitor of ACC 1 activity. Fresh black garlic IC50 (21 mg/ml) and fresh white garlic IC50 (77.50 mg/ml).
Drug delivery • Drug delivery is the study and development of the administration of drugs such that they arrive at the right site of the body at the appropriate rate. • Many drugs don’t make it to market because they cannot be effectively delivered. • It is now a multibillion $ concern and a huge field incorporating pharmacy, engineering, chemistry, biochemistry, molecular biology, etc.
Importance of drug delivery: The Ritonavir Story • Drug used for treatment of HIV – it is a protease inhibitor • It is crystalline and has different polymorphs • When discovered, the polymorph identified was form 1 (no other polymorphs were known at the time) • Drug launched into market in 1996 • In 1998 some forms of drug found to have differing properties (which was due to presence of new polymorph)
Importance of drug delivery: The Ritonavir Story • Within days to weeks, all the manufacturing sites in the US were producing form 2 and no longer producing form 1. • However, the manufacturing site in Italy was still able to produce form 1. • A team from US therefore went to Italy to investigate why they were still able to produce form 1. • Within a short time after the visit, Italy also started producing form 2. • The drug had to be pulled off the market and reformulated costing the company hundreds of millions of dollars
Aims of drug delivery • To develop controlled and specialized dosage forms • Biological reasons for needing this include poor absorption, poor solubility, poor taste, short half life, instability of the drug in certain parts of the body, desire for long term exposure to the drug among other reasons.
