Scientific Evidence

Just some of a large collection of Scientific Evidence backing Healthy Hibiscus (Hibiscus Sabdariffa)

Extracts courtesy U.S. National Institutes of Health

National Center for Biotechnology Information

http://www.pubmedcentral.nih.gov/

Phytother Research. 2005 May;19(5):369-75.

Phytochemical, pharmacological and toxicological aspects of Hibiscus sabdariffa L.: a review.

Ali BH, Al Wabel N, Blunden G.

Department of Veterinary Medicine, Al-Gaseem University, Buraydah, Al Gaseem 81999, Saudi Arabia.

This article reviews the reported phytochemical, pharmacological and toxicological properties of Hibiscus sabdariffa L. (English: roselle, red sorrel; Arabic: karkade), the calyces of which are used in many parts of the world to make cold and hot drinks. Nutritionally, these contain ascorbic acid (vitamin C). In folk medicine, the calyx extracts are used for the treatment of several complaints, including high blood pressure, liver diseases and fever.The pharmacological actions of the calyx extracts include strong in vitro and in vivo antioxidant activity. In rats and rabbits, the extract showed antihypercholesterolaemic, antinociceptive and antipyretic, but not antiinflammatory activities. In rat and man a strong antihypertensive action has been demonstrated. The effects of the calyx extracts on smooth muscles in vitro are variable, but they mostly inhibit the tone of the isolated muscles. In healthy men, consumption of H. sabdariffa has resulted in significant decreases in the urinary concentrations of creatinine, uric acid, citrate, tartrate, calcium, sodium, potassium and phosphate, but not oxalate. Oil extracted from the plant's seeds has been shown to have an inhibitory effect on some bacteria and fungi in vitro.The plant extracts are characterized by a very low degree of toxicity. The LD50 of H. sabdariffa calyx extract in rats was found to be above 5000 mg/kg. A single report has suggested that excessive doses for relatively long periods could have a deleterious effect on the testes of rats.In view of its reported nutritional and pharmacological properties and relative safety, H. sabdariffa and compounds isolated from it (for example, anthocyanins and Hibiscus protocatechuic acid) could be a source of therapeutically useful products. Copyright (c) 2005 John Wiley & Sons, Ltd.
PMID: 16106391 [PubMed - indexed for MEDLINE]

Ethnopharmacol. 2007 Feb 12;109(3):388-93. Epub 2006 Aug 15.

Mechanisms of the anti-hypertensive effect of Hibiscus sabdariffa L. calyces.

Ajay M, Chai HJ, Mustafa AM, Gilani AH, Mustafa MR.

Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.

Previous studies have demonstrated the anti-hypertensive effects of Hibiscus sabdariffa L. (HS) in both humans and experimental animals. To explore the mechanisms of the anti-hypertensive effect of the HS, we examined the effects of a crude methanolic extract of the calyces of HS (HSE) on vascular reactivity in isolated aortas from spontaneously hypertensive rats. HSE relaxed, concentration-dependently, KCl (high K(+), 80 mM)- and phenylephrine (PE, 1 microM)-pre-contracted aortic rings, with a greater potency against the alpha(1)-adrenergic receptor agonist. The relaxant effect of HSE was partly dependent on the presence of a functional endothelium as the action was significantly reduced in endothelium-denuded aortic rings. Pretreatment with atropine (1 microM), L-NAME (10 microM) or methylene blue (10 microM), but not indomethacin (10 microM), significantly blocked the relaxant effects of HSE. Endothelium-dependent and -independent relaxations induced by acetylcholine and sodium nitroprusside, respectively, were significantly enhanced in aortic rings pretreated with HSE when compared to those observed in control aortic rings. The present results demonstrated that HSE has a vasodilator effect in the isolated aortic rings of hypertensive rats. These effects are probably mediated through the endothelium-derived nitric oxide-cGMP-relaxant pathway and inhibition of calcium (Ca(2+))-influx into vascular smooth muscle cells. The present data further supports previous in vivo findings and the traditional use of HS as an anti-hypertensive agent.

J Ethnopharmacol. 2003 Jun;86(2-3):181-5

Chronic administration of aqueous extract of Hibiscus sabdariffa attenuates hypertension and reverses cardiac hypertrophy in 2K-1C hypertensive rats.
Odigie IP, Ettarh RR, Adigun SA.

Department of Physiology, College of Medicine of the University of Lagos, PMB 12003, Nigeria. This e-mail address is being protected from spambots. You need JavaScript enabled to view it

The effect of aqueous extract of petals of Hibiscus sabdariffa (HS) on the established stages of 2-Kidney, 1-Clip renovascular hypertension was investigated in Sprague-Dawley rats. Renovascular hypertension was induced by subjecting the animals to left renal artery clamping using a 0.2mm silver clip under ether anesthesia. Sham-operated (Sh-Op) rats served as controls.Six weeks after renal artery clamping, one group of hypertensive rats (blood pressure (BP) >140 mmHg) received HS (250 mg/kg/day) in drinking water (2K-1C+HS). The second group (2K-1C) and the sham-operated (Sh-Op) controls, received drinking water. BP was monitored weekly using rat-tail plethysmography.After 8 weeks, 2K-1C+HS had a reduction in systolic BP (139.6+/-1.6 mmHg) compared to 2K-1C (174+/-2.4 mmHg, n=5; P<0.001). No significant difference was found in BP of 2K-1C+HS and Sh-Op (139.6+/-1.6 mmHg versus 132+/-3.4 mmHg). A reduction in heart rate in 2K-1C+HS was observed (388+/-3.7 bpm versus 444+/-6.8 bpm in 2K-1C and 416+/-9.3 in Sh-Op, n=5; P<0.001). The hearts of 2K-1C were heavier than those of 2K-1C+HS (0.74+/-0.03 g versus 0.66+/-0.03 g, n=5; P<0.05). Cardiac weight of 2K-1C+HS was comparable to those of Sh-Op (0.57+/-0.04 g). Serum creatinine and plasma electrolytes were not different from controls.This study suggests that HS exhibits antihypertensive and cardioprotective effects in vivo and supports the public belief that HS may be a useful antihypertensive agent.

Screening of Tanzanian medicinal plants for anti-Candida activity
Deborah KB Runyoro, Mecky IN Matee, Olipa D Ngassapa, Cosam C Joseph, and Zakaria H Mbwambo
BMC Complement Altern Med. 2006; 6: 11. Published online 2006 March 30. doi: 10.1186/1472-6882-6-11.
PMCID: PMC1481531
| Abstract | Full Text | PDF–1.2M |

Hibiscus sabdariffa Affects Ammonium Chloride-Induced Hyperammonemic Rats
M. Mohamed Essa and P. Subramanian
Evid Based Complement Alternat Med. 2007 September; 4(3): 321–325. Published online 2006 December 1. doi: 10.1093/ecam/nel087.
PMCID: PMC1978237
| Abstract | Full Text | PDF–157K |

Natural health products that inhibit angiogenesis: a potential source for investigational new agents to treat cancer—Part 2
S.M. Sagar, D. Yance, and R.K. Wong
Curr Oncol. 2006 June; 13(3): 99–107.
PMCID: PMC1891180
| Abstract | Full Text | PDF–84K |

Natural health products that inhibit angiogenesis: a potential source for investigational new agents to treat cancer—Part 1
S.M. Sagar, D. Yance, and R.K. Wong
Curr Oncol. 2006 February; 13(1): 14–26.
PMCID: PMC1891166
| Abstract | Full Text | PDF–119K |

Ethnomedicines used in Trinidad and Tobago for urinary problems and diabetes mellitus
Cheryl A Lans
J Ethnobiol Ethnomed. 2006; 2: 45. Published online 2006 October 13. doi: 10.1186/1746-4269-2-45.
PMCID: PMC1624823
| Abstract | Full Text | PDF–370K | Supplementary Material |

Disruption of N-?cyl Homoserine Lactone-Mediated Cell Signaling and Iron Acquisition in Epiphytic Bacteria by Leaf Surface Compounds
Katerina Karamanoli and Steven E. Lindow
Appl Environ Microbiol. 2006 December; 72(12): 7678–7686. Published online 2006 September 22. doi: 10.1128/AEM.01260-06.
PMCID: PMC1694201
| Abstract | Full Text | PDF–397K |