Journal of Natural Remedies

S. Bryant , V. Huerta , K. Mihalik , S. H. Crixell , D. A. Vattem

Abstract

Pseudomonas aeruginosa (PAO1), an opportunistic pathogen in immune compromised patients is under the regulation of the LasR-RhlR system for quorum sensing (QS) mediated development of virulence. Natural products have recently become a promising source for deriving molecules that can potentially inhibit QS. Medicinal plants from Indian subcontinent used in traditional medicine are well known for their antimicrobial effects on a variety of human pathogens. However, few studies have investigated its QS related antivirulent activities. Our objective was to screen for the QS inhibitory properties of 16 high quality ayurvedic medicinal plants derived from Indian sub-continent, understand their mechanism of action and investigate their effect on the expression of QS regulated virulence factors in PAO1. QS inhibition of sub-lethal concentrations (SLC) of plant extracts was measured in violacein producing Chromobacterium violaceum bioassay model. Effect of these extracts on PAO1 virulent factors pyocyanin, elastase and total protease were quantified by standard protocols. Results indicated that all extracts reduced violacein production significantly. The results from modified screening assay suggested the primary mechanism of QSI was a combination of (1) reduction in AI formation and (2) inhibition of AI activity. The extracts reduced pyocyanin synthesis, inhibited the activity of elastase and other proteolytic enzymes.

Keywords

Quorum Sensing, Acylated Homoserine Lactones (AHL), Phytochemicals, Antimicrobial Activity, Medicinal Plants from India, Virulence Factors and Pseudomonas aeruginosa

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V. Huerta , K. Mihalik , K. Becket , V. Maitin , D. A. Vattem

Abstract

Excessive caloric intake, hyperglycemia, irregular blood lipid levels and resulting oxidative stress are accepted etiologies of Diabetes mellitus (DM) and associated co-morbidities including cardiovascular disease (CVD) and obesity (OB). These diseases are fast becoming leading causes of mortality in the developed and developing world. One important strategy for managing DM is managing postprandial hyperglycemia by reducing the digestion of carbohydrates by α-glucosidases. The risk factors for CVD and obesity can further be managed by regulating postprandial increases in blood triglyceride and fatty acid levels by modulating the activity of lipase. We investigated the potential of 18 different herbs, spices and medicinal plants (HSMP) commonly used in traditional medicine to reduce the energy harvest capacity of the mammalian gut by α-glucosidases and lipases in different model systems. In addition, we also assessed their abilities to confer antioxidant protection in biological systems. Our results indicate that several HSMP had the ability to prevent the digestion of carbohydrates by inhibiting α-amylase, maltase and sucrase. These HSMP were also effective in inhibiting the activity of lipase and therefore digestion of triglycerides in the mammalian gut. Based on our results, we have identified HSMP from different traditional medicines that can be used as an alternative and complimentary strategy to manage risk factors of DM and associated co-morbidities.

Keywords

Diabetes mellitus, Cardiovascular Disease, Obesity, Energy Harvest, α-glucosidase, Pancreatic Amylase, Disaccharidases, Maltase, Sucrase, Lipase, Enzyme Inhibition, Antioxidant Activity, Herbs, Spices, Medicinal Plants,Traditional Medicine

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