Of A Paniculata Extract And Some Diterpenoid Derivatives

A. paniculata extract was fractionated with solvents to obtain three fractions with different polarity—FA (ethyl acetate fraction), FB (butanol fraction), and FC (aqueous fraction). These were tested in the anesthetized normoten-sive Sprague-Dawley (SD) rat to evaluate their effects on the mean arterial blood pressure (MAP). MAP is the average systolic pressure that drives blood through the systemic organs and is thus a critical cardiovascular parameter. We found that FA did not reduce MAP in the anesthetized SD rat, while the crude aqueous extract of A. paniculata (WE), FB, and FC produced a significant fall in MAP in a dose-dependent manner without significant decrease in heart rate, the ED50 values for WE, FB, and FC being 11.4, 5.0, and 8.6 mg/kg, respectively (Fig. 4). These findings suggested that the hypotensive substance(s) in the crude water extract was concentrated in FB.

The lack of significant change in the heart rate suggests also that the hypotensive compound(s) in the FB fraction of A. paniculata extract may not have a direct action on the heart.

Figure 4 The effects of a crude water extract of A. paniculata (WE), its semi-purified butanol fraction (FB), and aqueous fraction (FC) on MAP of anaesthetized SD rats. Points represent the mean percent change in MAP of six animals in each group; bars indicate the SEM.

Figure 4 The effects of a crude water extract of A. paniculata (WE), its semi-purified butanol fraction (FB), and aqueous fraction (FC) on MAP of anaesthetized SD rats. Points represent the mean percent change in MAP of six animals in each group; bars indicate the SEM.

Pharmacological antagonist studies were performed using the FB fraction (5 mg/kg) to further evaluate the mechanism(s) of hypotensive action. The findings showed that the a-adrenoceptor, muscarinic cholinergic receptor, and ACE were not involved in the hypotensive action of FB. This was because this action was not affected by propranolol, atropine, and captopril, respectively (Fig. 5). Furthermore, in the presence of hexametho-nium, pyrilamine, and cimetidine, the decreases in MAP induced by FB were significantly attenuated, suggesting that the hypotensive action of FB might involve the autonomic ganglion and histaminergic systems. In addition, the data also indicated that the a-adrenoceptors are involved, since phentolamine almost completely abolished the hypotensive effect.

The following diterpenoids from A. paniculata were tested for their effects on the MAP of anesthetized SD rats: DA, DDA, andrographolide, andrographiside, neoandrographolide. We found that andrographolide, andrographiside, and neoandrographolide were without effect on the MAP

Figure 5 The effects of ganglionic, a- and h-adrenergic, muscarinic cholinergic, and histaminergic receptor blocking agents, and captopril on the hypotensive action of butanol fraction (FB) from crude water extract of A. paniculata. Columns represent the mean percent change in MAP of six animals; bars indicate the SEM. *Denotes that hypotensive responses of FB were significantly reduced from those of control.

Figure 5 The effects of ganglionic, a- and h-adrenergic, muscarinic cholinergic, and histaminergic receptor blocking agents, and captopril on the hypotensive action of butanol fraction (FB) from crude water extract of A. paniculata. Columns represent the mean percent change in MAP of six animals; bars indicate the SEM. *Denotes that hypotensive responses of FB were significantly reduced from those of control.

Figure 6 Effects of DA or DDA on MAP and HR of anesthetized SD rats. Each point represents the mean percentage decrease in MAP or HR of eight animals; bars indicate the SEM.

of the anesthetized rat. DDA dose-dependently decreased MAP and heart rate while DA had a weaker effect on these parameters than DDA (Fig. 6). It thus appeared that the hypotensive effect of A. paniculata could be contributed by at least these two diterpenoids.

Unraveling Alzheimers Disease

Unraveling Alzheimers Disease

I leave absolutely nothing out! Everything that I learned about Alzheimer’s I share with you. This is the most comprehensive report on Alzheimer’s you will ever read. No stone is left unturned in this comprehensive report.

Get My Free Ebook


Post a comment