Mitogen Activated Protein Kinase: Function and Responses to Different Stresses in Plants

Mitogen Activated Protein Kinase (MAPK) pathway is the most commonly studied signaling mechanisms, consisting of different groups of protein kinases that participate in regularly connecting interpretation of external stimuli that can change in gene expression or cellular organization within eukaryotic systems. The MAP kinase pathways functions in plants cell signaling (intra- and extra). MAPK cascades follow a response system. MAP kinases are the component of kinase constituents that deliver signals from sensors to responders in eukaryotes including plants. Several pathways are activated under different environmental stresses. Stimulating agents may be biological (biotic) like microbial infections or environmental (abiotic) like temperatures threshold, high salt concentration, drought, heavy metal, Ultra-violet radiation, ozone gases and reactive oxygen species (ROS). The involvement of MAPK signaling pathway in different stresses has been widely studied. In this review we also try to highlight MAPK cascades, its regulation, functions and recent findings in various cellular processes against stress conditions.

Development and Evaluation of Transdermal Drug Delivery System for Antihypertensive Agents

Aim of present study was to develop and evaluate matrix patches of Amlodipine besylate, Hydrochlorothiazide and combination of Amlodipine and Hydrochlorothizide containing enhancers for sustained and enhanced transdermal delivery. Hydroxypropylmethyl cellulose (HPMC) and poly vinyl pyrolidone (PVP K 30), were used as polymers. Propylene glycol (PG) and dibutyl phthalate (DBP) were used as plasticizers. Tween 20, Oleic Acid, IPA were used as enhancers. Methanol and Dichloromethane (DCM) were used as diluents.Patches were prepared by plate casting method. Polyvinyl alcohol was used to prepare backing membrane. Prepared polymeric matrix patches containing no enhancer were characterized for physical appearance, thickness, weight variation, moisture contents and moisture up take capacity. Fourier transform infrared (FTIR) spectroscopic studies of prepared patches were performed to identify any chemical and physical interaction between drug and excipients. In-vitro drug release studies were carried out in phosphate buffer pH 7.4 by using paddle over disc method. Release mechanism was elucidated by subjecting the in-vitro release data to kinetic analysis by using DD solver® excel based add in program. Scanning electron microscopy (SEM) was performed after release to further elaborate release process. In-vitro permeation studies were performed on Franz diffusion cell by using excised rabbit skin. Three different formulations containing Amlodipine, hydrochlorothiazide and combination of both the drugs were developed with polymer and excipients.Patches after incorporation of enhancers were characterized for physical properties, FTIR, PXRD and SEM analysis. In-vitro release and permeation studies were carried out to compare effect of enhancers and their concentration on release. Selected patch formulations were subjected to in-vivo studies by two periods, two parameters, parallel design for rats and parallel design in rabbits (n=6) for pharmacokinetic comparison with oral solution administration. Skin irritation studies were performed on healthy volunteers for patches by measuring level of erythema with Mexameter®. Fourty Eight formulations (A1 - A40, B1 - B4 & C1 - C4) were prepared by using different enhancers. All the prepared formulations qualified basic parameters of clarity, weight variation, thickness, folding endurance, % flatness etc. In the presence of enhancers initial burst release was seen in Amlodipine patches, Hydrochlorothiazide patches and combined drug patches. Oleic acid and Tween 20, have saturated shorter fatty acid side chains, showed highest enhancement effect with 1.73 and 2.01 folds increase in permeation rate when compared to control, respectively. In formulations (A1 – A16) maximum release was observed in formulation A3 (54%), A7 (62.25%), A11 (59.25%) and A15 (68.95%) having optimum concentration of IPA i.e., 125mg. Similarly, when amlodipine besylate and hydrochlorthiazide were formulated together (A17 – A28), maximum amlodipine release was observed in formulations A19 (75.28%), A22 (92.69%), A25 (77.36%) and A28 (95.87%) while maximum hydrochlorothiazide release was seen in formulations A19 (81.31%), A22 (91.54%), A25 (86.88%) and A28 (90.91%) due to the impact of oleic acid in the formulations. Likewise, formulations having maximum amount of tween 20 exhibited prominent release of hydrochlorothiazide i.e., A31 (69.83%), A34 (78.68%), A37 (80.98%) and A40 (83.60%). All the fabricated formulations A1 – A40 followed Higuchi kinetic model for their release and release mechanism was derived from Korsmeyer Peppas model. Nature of drugs i.e., Amlodipine and Hydrochlorothiazide in the finished transdermal patches was amorphous as confirmed by PXRD studies. Cumulative amount of drug permeated in formulations A1 – A16 was observed. Higher drug contents were permeated in formulation having higher enhancer concentration i.e., A3 (355µg/1.5 cm2), A7 (500µg/1.5 cm2), A11 (388µg/1.5 cm2) and A15 (492µg/1.5 cm2). Amount of drug permeated in these formulations was dependent on enhancer concentration in order of 75 mg>100 mg> 125 mg. Similar facts were seen in case of further developed formulations revealing enhancer dependant permeation. Toxicity studies had not shown any sort of skin reaction, alteration in biochemical profile of blood, histopathology and any effect on feed intake etc. It can be concluded that tween 20, IPA and Oleic Acid can be successfully employed as efficient permeation enhancers for transdermal delivery of Amlodipine and hydrochlorothiazide matrix patches, respectively. Moreover, a single patch of Amlodipine and Hydrochlorothiazide is capable to provide sustained continuous delivery of both the drugs for more than two days across skin. Thus application of combination (AML and HCT) transdermal patches can be used as an alternative of oral route for the treatment of hypertension.