 |
Leaves
of Ficus Schwarzii (Photo
taken from Krishnan, P.; Lee, F.-K.; Yap, V. A.; Low, Y.-Y.; Kam, T.-S.; Yong,
K.-T.; Ting, K.-N.; Lim, K.-H. J. Nat. Prod. 2020, 83 (1),
152–158.) |
High blood
pressure, also called hypertension is a medical condition characterized by the
systolic blood pressure of ≥140 mm Hg
and the diastolic blood pressure of ≥ 90 mm Hg.1 In 2000, about 26%
of the adult population worldwide had hypertension and this number is projected
to increase to about 29% by 2025.2 It is associated with several
medical conditions such as stroke, renal failure and cardiovascular diseases.3
Although antihypertensive medications are widely available, a segment of
patients still suffers from resistant hypertension, a condition in which blood
pressure remains above goal (140/90 mm Hg). This, despite the patient is concurrently
taking three or more antihypertensive drugs of different classes for treatment.4
While scientific studies in resistant hypertension are numerous, no single medication
has been specifically developed for the treatment of resistant hypertension.5
Moreover, the uses of drug combinations in the treatment of hypertension are
often restricted by adverse effects associated with the particular class of
antihypertensive drug.6 The current situation, therefore, shows the urgent
need to discover molecules that act via novel mechanism of action to address
the resistant hypertension issue.
A series of alkaloids has been recently isolated from
the leaves of Ficus Schwarzii, a previously uninvestigated Ficus
species in Malaysia.7 These alkaloids named schwarzinicines A – G represent
the first examples of 1,4-diarylbutanoid-phenethylamine conjugates. Their chemical
structures are determined by chemical analysis techniques of mass spectroscopy,
1D and 2D NMR spectroscopy.
The vasorelaxant activities of schwarzinicines A−D were then evaluated in drug-precontracted
rat isolated aortic rings. Schwarzinicines A−D were found to exhibit pronounced
vasorelaxation effects in the aortic tissues in a concentration-dependent
manner. The maximum relaxation magnitude produced by all the four compounds was
significantly greater than that of dobutamine, a known phenylalkylamine
vasorelaxant agent. It is worth to note that the potency of all the compounds
tested was comparable. Thus, it suggested that minor variations in substituents
or substitution patterns on the aryl ring C have little effect on their activities.
While more
studies are being carried out on the schwarzinicine alkaloids and they will be
reported in due course, it is promising for these vasorelaxant alkaloids to
be developed into useful therapeutic agents in the hope to treat resistant
hypertension.
References
1.
Chobanian,
A. V.; Bakris, G. L.; Black, H. R.; Cushman, W. C.; Green, L. A.; Izzo, J. L.;
Jones, D. W.; Materson, B. J.; Oparil, S.; Wright, J. T.; Roccella, E. J. JAMA
2003, 289 (19), 2560–2572.
2.
Kearney,
P. M.; Whelton, M.; Reynolds, K.; Muntner, P.; Whelton, P. K.; He, J. Lancet
2005, 365 (9455), 217–223.
3.
Messerli,
F. H.; Williams, B.; Ritz, E. Lancet (London, England) 2007, 370
(9587), 591–603.
4.
Sarafidis, P. A.; Bakris, G. L. J. Am. Coll. Cardiol. 2008,
52 (22), 1749–1757.
5.
Pimenta, E.; Calhoun, D. A. Curr. Hypertens. Rep. 2016,
18 (4), 25.
6.
Gradman, A. H.; Basile, J. N.; Carter, B. L.; Bakris, G. L. J.
Am. Soc. Hypertens. 2010, 4 (2), 90–98.