Antihypertensive Effect of Heimia Salicifolia
In order to evaluate the effects produced by the alkaloids of leaves from H. salicifolia on the blood pressure of rats, four alkaloids from H. salicifolia were isolated by column and thin layer chromatography. The alkaloids’ antihypertensive effects on angiotensin II-caused acute hypertension as well as their hypotensive effects on normotensive rats were studied. The alkaloid 3, the most abundant isolated alkaloid, turned out to be the most effective, while the other alkaloids showed a slight, non-significant vascular activity. Their mixture showed an additive effect, though slightly different from the alkaloid 3.
Emerging features of brain angiotensin receptors
In mammalian brain, angiotensin II AT1 and AT2 receptor subtypes are apparently expressed only in neurons and not in glia. AT1 and AT2 receptor subtypes are sometimes closely associated, but apparently expressed in different neurons. Brain AT1/AT2 interactions may occur in selective cases as inter-neuron cross talk. There are two AT1 isoforms in rodents. AT1A, which predominates, and AT1B. There are also important inter-species differences in receptor expression. Relative lack of amino acid conservation in the gerbil gAT1A receptor substantially decreases affinity for the AT1 antagonists. AT1 receptors are expressed in brain areas regulating autonomic and hormonal responses. AT1A receptors are heterogeneously regulated in a number of experimental conditions. In specific areas, AT1A receptors are not normally expressed, but are induced under influence of reproductive hormones in dopaminergic neurons. There are AT1 and AT2 receptors also in areas related to limbic, sensory and motor functions and their expression is developmentally regulated. A picture is emerging of widespread, neuronally localized, heterogeneously regulated, closely associated brain angiotensin receptor subtypes, modulating multiple functions including neuroendocrine and autonomic responses, stress, cerebrovascular flow, and perhaps brain maturation, neuronal plasticity, memory and behavior.
Catalytic removal of tert-butyldimethylsilyl (TBS) ether by PVP-I
Abstract A mild, efficient and rapid protocol the deprotection of alcoholic TBDMS ethers using PVP-1 as catalyst in methanol, the procedure of deprotection of various TBDMS ethers were found to be very convenient, easy work-up, high yielding.