Roselle is an erect, branched, nearly smooth annual herb, 1 to 2 meters in height. Stems are purplish. Leaves are 8 to 12 centimeters long, variable in shape, entire or deeply 3- or 5-lobed, the lobes oblong to oblong-lanceolate. Calyx is somewhat hairy, lobes are pointed, connate below the middle, forming a fleshy cup. Corolla is pink with a dark center, about 5 centimeters long. Fruit is ovoid, pointed, hairy, about 2.5 centimeters long, enclosed by a fleshy and enlarged calyx.
- Planted for ornamental purposes and its edible calyces.
- Not spontaneous.
- Introduce post-Spanish colonization.
- Native of tropical Africa.
• The dried calyces yield among others: cellulose, insoluble and soluble ash, tartaric acid, malic acid.
• Calyces are high in calcium, niacin, riboflavin, and iron.
• Food value per 100 g of fresh edible portion: Moisture 9.2 g, protein 1.145g. fat 2.61g, fiber 12 g, ash 6.9 g, calcium 1,263 mg, phosphorus 273.2 mg, iron 8.98 mg, carotene 0.029 mg, thiamine 0.117 mg, riboflavin 0.277 mg, niacin 3.765 mg, ascorbic acid 6.7 mg.
• The flowers yield a coloring matter that contain gossypetin, quercetin, hibiscetin and free protocatechuic acid.
• Bitter seeds contain 20% oil with 26% albuminoids.
• Leaves yield oxalic acid.
• Analysis of unextracted (UE) and extracted (E) roselle seeds showed 15.36% (UE) 27.50% (E) digestible crude protein, 75.81% (UE) 68.83% (E) total digestible nutrients, 84.06% (UE) 64.23% (E) starch value, and 3184 kcal/kg (UE) 2891 kcal/kg (E) calculated metabolizable energy.
• Leaves considered emollient, stomachic, scorbutic and febrifuge.
• Seeds are diuretic and tonic.
• Flowers considered tonic and aperitive.
Leaves and flowers.
Culinary / Nutritional
• Cultivated ornamentally and for the red and fleshy calyces that surround the fruit used for making jellies, wine and other food products. The jam, jelly, and sauce are similar in appearance and taste to cranberries.
• Young leaves used as a substitute for spinach; used in cooking of curries, meat or fish, and the native dish "sinigang."
• In Myanmar, green leaves are the main ingredient in making chin baung kyaw curry.
• Calyces are high in calcium, niacin, riboflavin, and iron.
• Leaves used as emollient.
• Lotion made from leaves used for sores.
• Decoction of seeds used for dysuria and strangury; for mild dyspepsia and debility.
• In Brazil, drink made from the plant, considered refrigerant and used for fevers.
• A boiled drink prepared from the fruit and calyx, dashed with salt, pepper, asafoetida and molasses, used for biliousness.
• Fruit used as antiscorbutic.
• Seeds are diuretic and tonic.
• In Chad, infusion of calyces used for plethora, bronchitis and coughs.
• Heated leaves applied to cracks in the feet; also, to boils and ulcers to hasten healing and maturation.
• In India seed decoction used for dysuria, strangury and mild dyspepsia.
• In Nigeria, seed decoction used to enhance or induce lactation in cases of poor milk production. (see study below) (27)
Plant yields bast fiber from the stems; used a jute substitute in making burlap.
Plant yields a coloring matter used for food coloring.
• Antihypertensive: A study evaluating the effect of sour tea (H sabdariffa) on essential hypertension showed significant lowering of both systolic and diastolic blood pressure. (1) A randomized, double-blind, placebo-controlled study examined the anti-hypertensive effects of H. sabdariffa tisane (hibiscus tea) consumption in humans. Results suggest daily consumption of hibiscus tea, in an amount readily incorporated into the diet, lowers BP in pre- and mildly hypertensive adults. (22)
• Antimutagenic: A study of an 80% ethanol extract of roselle showed antimutagenic activity against MAM acetate, a colon carcinogen. (2)
• Anti-Atherosclerotic / Hypolipidemic: A study of HB extract suggests it inhibits serum lipids and shows and anti-atherosclerotic activity. (3)
• Nephroprotective / Diabetic Nephropathy Amelioration: Study showed HS extract possesses potential effects to ameliorate diabetic nephropathy in STZ induced type 1 diabetic rats via improving oxidative status and regulating Akt/Bad/14-3-3 signaling.(4)
• Galactagogue / Lactogenic Effect: A study showed the seed extract of H sabdariffa possesses lactogenic activity, enhancing serum prolactin level which is the principal lactogenic hormone secreted by the anterior pituitary. Results establish the ethnomedical use of the seeds as a galactagogue. (•) Study showed the serum prolactin level of extract-treated rats showed a dose-dependent significant increase when compared to the control group. (5)
• Anti-Hyperammonemia: A study showed administration of extract of HS altered the activities of the liver marker enzymes in ammonium chloride-induced hyperammonemic rats. (7)
• Antihypertensive / Seed: Study showed the aqueous seed extract of HS produced a significant reduction in cat blood pressure. (8)
• Antioxidant: A study showed the protective role of extract of HS against lipid peroxidation and suggests an antioxidant potential to be used for therapeutic purposes.
• Hypolipidemic: A study of HS dried calyx ethanolic extract on the serum lipid profile of Sprague-Dawley rats showed triacylglycerols and LDL levels to be significantly less in all groups. All groups had lower cholesterol levels compared to control. No significant results were found on the HDL levels (10)
• Antiviral / Anti-Measles Virus: A study of leaf extracts of red and green leaved Hibiscus sabdariffa showed antiviral activities against the Measles Virus. (12)
• Hepatoprotective / Carbon Tetrachloride Hepatotoxicity: A study of the aqueous ethanol extract of the calyx of Hibiscus sabdariffa on carbon tetrachloride-induced liver damage showed healing of oxidative liver damage as determined by serum enzyme levels and liver thiobarbituric acid reactive substances levels. (13)
• Antioxidant / Seeds: Study investigated the antioxidant activity of an ethanolic seed extract of H sabdariffa in toxicity induced by chronic administration of sodium nitrate in wistar rats. Results showed alleviation of induced toxicity by the antioxidant effect of HS. Substantial amounts of Vitamin E and Vitamin C in the seed oil observed on preliminary phytochemical screening may be responsible for the antioxidant effect. (14)
• Anti-Obesity: Study investigated the effect of a calyx extract on fat absorption-excretion and body weight in rats. Results showed a significant increase in the amount of fatty acid in the feces. The components of the Hs extract at the intermediate and higher concentrations could be considered possible antiobesity agents. (15)
• Staining Effect: Roselle extract shows reasonable potential as a candidate nuclear stain especially when modanted with iron alum or mordanted with potassium alum and acidified with acetic acid. (16)
• Safety Study: Study concludes Hibiscus sabdariffa is probably a safe medicinal plant, short-term administration of the HS did not show harmful effects on body water and electrolyte levels.
• Review / Hypertension Study / No Effect: Current trials of HS in reducing high blood pressure were poor. Four randomized controlled studies do not provide reliable evidence to support recommending HS for the treatment of primary hypertension in adults. (18)
• Lactogenic Study / Prolactin Effect: Study evaluated the effect of an ethyl acetate fraction of seed on pituitary prolactin and milk production in albino rats. Results showed a significant increase in prolactin level. Results infer the EA seed fraction has lactogenic activity, increasing pituitary prolactin level and milk production in lactating female albino rats. The LD50 of ethyl acetate fraction was above to be above 5000 mg/kg. (19)
• Review / Treatment of Hypertension and Hyperlipidemia / Animal and Human Studies: This review reports of a comprehensive body of evidence suggesting that HS extracts are promising as treatment of hypertension and hyperlipidemia. Of the potential hypolipidemic and hypotensive mechanisms, the most common explanation is the antioxidant effects of the anthocyanins inhibition of LDL-C oxidation, which impeded atherosclerosis, an important cardiovascular risk factor. Author suggests more high quality animal and human studies to provide recommendations for its potential public health benefit. (23)
• Toxicity Study: Study evaluated acute and chronic toxicities of water extract from calyces of Hibiscus sabariffa in male and female rats. A single oral administration of extract in the amount of 5,000 mg/kbw did not produce acute toxicity. A 270-day chronic toxicity evaluation at doses of 50, 100, and 200 mg/kbw did not cause chronic toxicity in rat. (25)
• Protective Against Oxidative Stress Induced Damage on RBC Membrane: Study evaluated the effect of an aqueous extract of H. sabdariffa calyx on hydrogen peroxide induced oxidative stress on rat RBC membranes. The extract showed a protective effect by reducing oxidative stress damage in vitro. Dose concentrations of 0.5 mg/ml Roselle extract reduced peroxidation on lipids by reducing the concentration of MDA and helped RBC membrane antioxidant defense system by increasing GSH and lowering SOD concentrations. (26)
• Safety Study During Pregnancy and Lactation: Study reviewed the literation on use, safety, efficacy, and pharmacology during pregnancy and lactation. Results showed no scientific evidence to support use of H. sabdariffa during pregnancy and lactation. In vitro studies of seeds in animals suggest a lactogenic effect. Animal studies have also shown delayed puberty, elevation of body weight and BMI in female rats. Authors advise caution with the use of HS during pregnancy and lactation until human research determines its safety. (27)
• Antifungal Synergism with Voriconazole in Fluconazole-Resistant Candida albicans: Study reports on the antimicrobial effect of H. sabdariffa extract, a common herbal drink, in combination with voriconazole or fluconazole against C. albicans isolates. Results showed a high degree of synergism of the extract with voriconazole against fluconazole-resistant C. albicans. The extract showed no effect with fluconazole. (28)
• Hypotensive Effect / Anthocyanins: Extraction study on H. sabdariffa analyzed total phenol content and antioxidant capacity using various assays. Highest concentration was through water extraction, providing the highest concentrations of cyanidin 3-sambubioside and delphinidin 3-sambubioside. Partition coefficients of anthocyanins showed aglycone and glucoside forms of hibiscus anthocyanins behave differently when in the presence of cell wall material, which could effect absorption and bioactiviy of the anthocyanins. A human crossover study on daily consumption of H. sabdariffa juice for 8 weeks showed a significant reduction in systolic blood pressure. Study suggests regular consumption of HS extracts may reduce cardiovascular risk. (29)
• Effect on Spermatogenesis / Fruit: Study evaluated the effect of aqueous fruit extract of Hibiscus sabdariffa on spermatogenesis and sperm of adult male mice. Results showed an adverse effect on spermatogenesis and sperm parameters in mice, with significant differences in FSH, LH, and testosterone hormones, with testes histology showing a significant decrease in lumina spermatozoa. (30)
• Corrosion Inhibition: Study of calyx extract of H. sabdariffa on mild steel corrosion showed suppression corrosion in both acid media (2M HCl and 1M H2SO4) through mix-inhibition mechanism. Inhibition efficiency increase with increase in extract concentration and synergistically increased in the presence of halide ions. (31)
Interactions / Toxicology
• Studies in healthy volunteers showed altered chloroquine, acetaminophen and diclofenac pharmacokinetics. (32) Hypotensive effects might be of concern in patients on antihypertensives.
• The LD50 of ethyl acetate fraction of seed was above to be above 5000 mg/kg. (19) The median lethal dose of the calyx extract in rats is estimated to be higher than 5 g/kg. (Ali BH, Al Wabel N, Blunden G. Phytochemical, pharmacological and toxicological aspects of Hibiscus sabdariffa L.: a review. Phytother Res . 2005;19(5):369-375.) (32)
Teas and extracts in the cybermarket.