Kamyab, et al.

lower blood pressure. This plant also inhibited angiotensin II, which is an effective vasoconstrictor. The ability of HS
I-converting enzyme, iron (II), and sodium nitroprusside- extract to impede ACE activity was explored in a randomized
induced lipid peroxidation in the heart of a rat model clinical study.71 Daily consumption of HS can effectively
in an in vitro study.63 Annona muricata is a member of treat high blood pressure in stage one hypertension
the family of custard apple trees and grows natively in along with dietary and lifestyle modifications.72,73 It
Central America and Caribbean. It has been revealed has been revealed that daily consumption of hibiscus
that the leaf extract of this plant reduces elevated blood tea in a concentrated bio-energized form may prove to
pressure by decreasing peripheral vascular resistance.64 be an influential component in cardiovascular health
Desmodium styracifolium showed antihypertensive management and lead to lower blood pressure levels.74
properties in two ways: a: mediation through cholinergic Improving a patient’s lipid profile is the main therapeutic
receptor stimulation, and b: potentiation by barriers of effect of HS. The anthocyanins in this plant, inhibit low-
the autonomic ganglion and alpha-adrenoreceptor.65 It density lipoprotein oxidation and consequently reduce the
has been found that Lepidium latifolium has hypotensive atherosclerotic process.75 Moreover, H. sabdariffa extracts
effects in rats due to its diuretic action; therefore, it can be significantly inhibit adipogenesis by regulating adipogenic
used as an antihypertensive plant.66 Viscum album presents signaling pathways, modulating the gene expression
biologically active principles that may act as inducers of the of certain microRNAs, decreasing LDL oxidation, and
nitric oxide/soluble guanylate cyclase pathway.67 Studies in through transcription factors.75 It has been shown that
this field have shown that a wide range of herbal remedies HS contains a compound that causes the release of nitric
can be used for the treatment of hypertension. The studies oxide from the vascular endothelium and increases renal
in this section are summarized in Table 5. filtration, thereby lowering blood pressure.76 It has also
The main point of the studies discussed in this section been exhibited that HS can decrease the systolic and
and shown in Table 5 is that most research has been diastolic blood pressure (BP).77 Consumption of HS
developed on animal models, and there are few clinical with adapted doses between 10-20 g daily for one month
trial studies. The primary purpose of the current study is to was associated with an improvement in both diastolic
introduce HS as an herbal remedy for high blood pressure, and systolic BP, even in patients simultaneously taking
as discussed below. antihypertensive medications.78 An interesting study
showed that HS has cardioprotective and antihypertensive
Hibiscus sabdariffa for Hypertension effects in vivo and agreed with the public belief that HS
Angiotensin-converting enzyme (ACE) is an essential part can be a valuable antihypertensive agent. Vitamin C
of the renin–angiotensin system (RAS) which controls and anthocyanin are the main antioxidant compounds
blood pressure by regulating the volume of body fluids.68,69 in the HS plant. Accordingly, that these antioxidants
Leonard T. Skeggs, Jr. discovered this enzyme in 1956. This act as free radical scavengers in 2K-1C hypertension
enzyme converts the hormone angiotensin I to the active remains hypothetical.79 The antihypertensive effects of
vasoconstrictor (angiotensin II).68 Ultimately, ACE raises HS calyces was revealed in a report. This result possibly
blood pressure by constricting vessels. ACE inhibitors are interfered with the endothelium-derived nitric oxide-
widely used as pharmaceutical drugs in cardiovascular cGMP-relaxant pathway and inhibition of calcium (Ca2+)-
diseases.69,70 The ability of HS aqueous extract to block the influx into vascular smooth muscle.80 Another research
action of ACE is an additional hypotensive mechanism. showed that continuous consumption of HS calyx extract
Anthocyanins, as the main HS extract, compete with the improved myocardial capillarization in spontaneously
ACE binding site, thereby inhibiting the formation of Ang hypertensive rats.81 In an innovative study, the effects of

Table 5. Frequently used antihypertensive plants with their relative mechanism of action.

Plants Model Mechanism of action Ref.

Camellia sinensis Human Increases flow-mediated dilation (FMD) 60

Coriandrum sativum Rat Deactivates ROS produced by β-adrenoceptor stimulation 61

Reduces ROS, increases antioxidants, serum glutathione (GSH) levels, glutathione re-
Salviae miltiorrhizae Rabbit 62
ductase (GSSG‐R), superoxide dismutase (SOD), paraoxonase (PONase)
Inhibits angiotensin I-converting enzyme, iron (II), and sodium nitroprusside-induced lipid
Zingiber officinale Rat 63
peroxidation
Annona muricata Rat Decreases peripheral vascular resistance 64

Desmodium styracifo- Mediated through cholinergic receptor stimulation, potentiated by barriers of autonomic 65
Rat
lium ganglion and alpha-adreno receptor
Lepidium latifolium Rat Has hypotensive effects due to its diuretic action 66

Some biologically active principles that may act as inducers of the nitric oxide/soluble
Viscum album Rat 67
guanylate cyclase pathway

511 | Pharmaceutical Sciences, 2022, 28(4), 506-516