Blood pressure lowering effect and vascular activity of Phyllanthus niruri extract: The role of NO/cGMP signaling pathway and β-adrenoceptor mediated relaxation of isolated aortic rings

An insight into the potent medicinal plant Phyllanthus amarus Schum. and Thonn

Phyllanthus amarus Schum. and Thonn., a globally distributed herb is known for its several therapeutic potentials. P. amarus has a long history of use in the traditional system of medicine for over 2000 years owing to its wide array of secondary metabolites that confer significant medicinal attributes. Research on various aspects including ethnobotany, phytochemistry to bioactivity, or pharmacological studies has been conducted over the past several decades on this potent herb. P. amarus extracts have shown a broad range of pharmacological activities like hepatoprotective, antioxidant, antiviral, antimicrobial, antidiabetic, anti-inflammatory, anticancer, antimalarial, nephroprotective, diuretic, and several other properties. The present review compiles and covers literature and research of several groups across past decades to date and focuses on how the therapeutic significance of this plant can be further explored for future research either as herbal formulations, alternative medicine, or in the pharmaceutical industry.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13237-022-00409-z.

Preclinical Evaluation of the Antihypertensive Effect of an Aqueous Extract of Anogeissus leiocarpa (DC) Guill et Perr. Bark of Trunk in L-NAME-Induced Hypertensive Rat

BACKGROUND

The present study investigates the effect of an aqueous extract of Anogeissus leiocarpa (AEAL) on normotensive Wistar rats and its chronic antihypertensive effects in L-NAME-induced hypertensive rats by using a non-invasive tail-cuff model.

METHODS

The effects of AEAL (50mg/kg) and NaCl 0.9% on blood pressure were investigated by daily oral administration in normotensive Wistar rats over four weeks. L-NAME-induced hypertensive rats were produced by L-NAME (40mg/kg) daily oral administration for two weeks. For chronic antihypertensive effects, induced hypertensive rats have received L-NAME in combination with AEAL (10 or 50mg/kg/day) for two following weeks.

RESULTS

In normotensive rats, daily administration of AEAL (50mg/kg) has no significant effect on their blood pressure, which was similar to that of the control group. L-NAME's daily oral administration induces a progressive increase in systolic blood pressure (SBP) from 115.8 ± 7.9mmHg to 153.5 ± 4.6mmHg after two weeks, which was maintained to the end of the treatment. In L-NAME-induced hypertensive rats, AEAL (50mg/kg/day) significantly decreases the SPB from 160.0 ± 5.8 mmHg to 108.8 ± 2.7mmHg after only four days of administration. However, the lower dose of AEAL (10mg/kg) also normalized the SBP of L-NAME-induced hypertensive rats but only evident after seven days of administration. Moreover, AEAL does not effect on the serum biochemical parameters (ALAT, ASAT, CREAT, etc.) and any macroscopic adverse effect was detected on the sensible organs involved during hypertension. In the aorta rings from treated rats, AEAL (50mg/kg/day) alone or in combination with L-NAME has enhanced the vasodilation effect of acetylcholine. However, the vasodilation effect of AEAL alone or in association with L-NAME has enhanced the sodium nitroprusside effect in treated rat aorta rings after autopsy.

CONCLUSION

These findings suggest that AEAL affords significant antihypertensive effects against L-NAME-induced hypertensive rats without modification of serum parameters and deleterious effects.

Antihypertensive Effects of the Methanol Extract and the Ethyl Acetate Fraction from Crinum zeylanicum (Amaryllidaceae) Leaves in L-NAME-Treated Rat

Arterial hypertension (AHT) is a leading cardiovascular disease, with a high negative impact on the quality of life. Crinum zeylanicum (C. zeylanicum) leaves extract is used in the West region of Cameroon to treat AHT and heart problems. This study aimed to investigate the antihypertensive effect of C. zeylanicum extract in N^ω-nitro-L‐arginine methyl ester- (L‐NAME-) induced hypertensive rats. The aqueous extract of C. zeylanicum (LAE) was obtained by lyophilizing the juice of triturated fresh leaves. The methanol extract (LME) prepared by maceration of the dried leaves was further partitioned to chloroform (LCF), ethyl acetate (LEAF), and residual (LRF) fractions. The total polyphenol, flavonoid content, and antiradical potentials of these extracts were determined. The curative antihypertensive and renal function protective effects of LME and LEAF were evaluated in vivo on L-NAME-induced hypertensive rats. Hypertension was induced in rats by oral administration of L-NAME (30 mg/kg/day) for 3 consecutive weeks. Thereafter, plant extracts were administered orally at the doses of 30, 60, and 120 mg/kg/day, concomitantly with L-NAME for three other weeks. Body weight, heart rate, and arterial blood pressure were measured at the end of each week throughout the experimental period. At the end of the treatment, 24-hour urine and plasma were collected to assay nitric oxide (NO), creatinine, and protein. The results revealed that LEAF has the higher content of total polyphenol and flavonoid and exhibited the best antiradical potential. Moreover, treatment of hypertensive rats with LME and LEAF significantly (p < 0.001) reduced AHT and heart rate. LME and LEAF significantly increased rat's body mass, plasmatic NO, and urinary creatinine and reduced urine NO and protein contents as compared to the L-NAME group. LME and its LEAF possess potent antihypertensive effects and further protect the renal function in L-NAME-induced hypertensive rats, thus supporting the use of C. zeylanicum in the management of AHT.

Phytotherapy for Cardiovascular Disease: A Bench-to-Bedside Approach

At present, cardiovascular disease (CVD) remains the leading cause of morbidity and mortality worldwide, and global trends suggest that this panorama will persist or worsen in the near future. Thus, optimization of treatment strategies and the introduction of novel therapeutic alternatives for CVD represent key objectives in contemporary biomedical research. In recent years, phytotherapy-defined as the therapeutic use of whole or minimally modified plant components-has ignited large scientific interest, with a resurgence of abundant investigation on a wide array of medicinal herbs (MH) for CVD and other conditions. Numerous MH have been observed to intervene in the pathophysiology of CVD via a myriad of molecular mechanisms, including antiinflammatory, anti-oxidant, and other beneficial properties, which translate into the amelioration of three essential aspects of the pathogenesis of CVD: Dyslipidemia, atherosclerosis, and hypertension. Although the preclinical data in this scenario is very rich, the true clinical impact of MH and their purported mechanisms of action is less clear, as large-scale robust research in this regard is in relatively early stages and faces important methodological challenges. This review offers a comprehensive look at the most prominent preclinical and clinical evidence currently available concerning the use of MH in the treatment of CVD from a bench-to-bedside approach.

Antioxidant Food Components for the Prevention and Treatment of Cardiovascular Diseases: Effects, Mechanisms, and Clinical Studies

Cardiovascular diseases (CVDs) have gained increasing attention because of their high prevalence and mortality worldwide. Epidemiological studies revealed that intake of fruits, vegetables, nuts, and cereals could reduce the risk of CVDs, and their antioxidants are considered as the main contributors. Moreover, experimental studies showed that some antioxidant natural products and their bioactive compounds exerted beneficial effects on the cardiovascular system, such as polyphenols, polysaccharides, anthocyanins, epigallocatechin gallate, quercetin, rutin, and puerarin. The mechanisms of action mainly included reducing blood pressure, improving lipid profile, ameliorating oxidative stress, mitigating inflammation, and regulating gut microbiota. Furthermore, clinical trials confirmed the cardiovascular-protective effect of some antioxidant natural products, such as soursop, beetroot, garlic, almond, and green tea. In this review, we summarized the effects of some antioxidant natural products and their bioactive compounds on CVDs based on the epidemiological, experimental, and clinical studies, with special attention paid to the relevant mechanisms and clinical trials.

Vasorelaxant Effects Induced by Red Wine and Pomace Extracts of Magliocco Dolce cv

Several epidemiological studies demonstrate that moderate (red) wine consumption may afford protection against cardiovascular diseases. Protection is ascribed to the biological activity of wine components, many of which, however, are discarded during winemaking. In vitro rat thoracic aorta rings contracted with phenylephrine or KCl were used to assess the vasorelaxant activity of extracts from wine pomaces (seeds and skins) of the Calabrian autochthonous grape variety Magliocco dolce (Arvino). NMR spectroscopy was used to ascertain their chemical composition. Data demonstrate that seed and skin, but not must, extracts are capable of relaxing vascular preparations in an endothelium-dependent manner, similarly to the red wine extract, due to the presence of comparable amounts of bioactive constituents. In rings pre-contracted with 20–30 mM KCl, only seed extracts showed a moderate relaxation. The most efficacious vasodilating extract (wine) showed a good antioxidant profile in both [(2,2-diphenyl-1-picrylhydrazyl)acid] radical (DPPH) and [2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid)] radical (ABTS) assays. In conclusion, winemaking from Magliocco dolce grape can provide potentially health-promoting by-products useful in cardiovascular disease management.