Hibiscus sabdariffa Linn (Roselle) is an annual shrub commonly used to make jellies, jams, beverages and used traditionally as a medicinal plant for the treatment of various ailments. The present study was undertaken to investigate the effect of aqueous extract of Hibiscus sabdariffa calyx on male rat reproductive hormones. Twenty (20) male wistar rat weighing 0.25±0.2 kg were grouped into one water control group and three experimental groups. While the water control group received 1.0 ml of water for 28 days, the experimental group were administered 250 mg/kg oral doses of aqueous extract of H.sabdariffa calyx. The effect on the basal levels of follicle stimulating hormone, testosterone, prolactin, luteinizing hormone and estradiol were conducted in experimental animals. The 28 days oral administration of aqueous extract of H.sabdariffa L. is associated with a decreased circulating plasma levels of follicle stimulating hormone, Testosterone and prolactin in male wistar rat compared with the control group. The study did not show a change in the plasma levels of both circulating luteinizing hormone and estradiol following 28 days oral administration of H.sabdariffa calyx to the experimental animal. Moreover, Marked histological changes were detected on testes of the experimental animals after 28 days of administration. This may indicate that H.sadariffa calyx extract can cause both morphological and physiological testicular damage. The study concluded that H. sabdariffa calyx extract at a dose of 250 mg/kg caused mild effects on rat reproductive hormones.
Endocrine disrupting compounds (EDCs) are natural or synthetic compounds that have the ability within the body to alter endocrine functions often through mimicking or blocking endogenous hormones (James et al., 2013). These actions on the endocrine system have resulted in developmental deficits in various invertebrate and aquatic species (Crain et al., 2007; Elango et al., 2006) and mammals (Christopher et al., 2012). Exposures in adulthood have consequences but fetal and early life exposures appear to have more severe effects that persist through life (Rubin and Soto, 2009). Among these classes of chemicals are phytoestrogens that show effects suggestive of estrogenicity, such as binding to the estrogen receptors, induction of specific estrogen-responsive gene products, stimulation of estrogen receptor(s) and positive breast cancer cell growth (James et al., 2013). Through these interactions by acting as agonists or antagonists, EDCs are able to alter the activity of response elements of genes, block natural hormones from binding to their receptors, or in some cases increase the perceived amount of endogenous hormone in the body by acting as a hormone mimic to its receptor (Ze-hua et al., 2010).
Hibiscus sabdariffa Linn (Roselle) is an annual shrub commonly used to make jellies, jams and beverages (Sirag et al., 2013). The brilliant red colour of its calyx makes it a valuable food product, a part from its multitude of traditional medicinal uses (Sirag et al., 2013). Infusions of the calyces are considered as diuretic, cholerectic, febrifugal and hypotensive, decreasing the viscosity of the blood and stimulating intestinal peristalsis (Salleh et al., 2002). Roselle calyx extract is a good source of antioxidants from its anthocyanins and associated with antitumor and inhibitory effects on the growth of several cancer cells (Ajiboye et al., 2011).
Extracts of H.sabdariffa calyces have been reported to be rich in phytoestrogens (Adigun et al., 2006; Orisakwe et al., 2004; Brian et al., 2009; Omotuyi et al., 2011) and some reports indicated that H.sabdariffa calyces have estrogenic effects, although exact estrogen-like ingredient is not determined (Ali et al., 1989).
This study was undertaken to determine to which extent H.sabdariffa calyces extract alters the basal levels of selected reproductive hormones: Follicle stimulating hormone, testosterone, prolactin, estradiol, and luteinizing hormone as well as the histological features male wistar rat testes.
1.1 Literature Review
Hibiscus sabdariffa L. also known as roselle, is an ideal crop for developing countries as it is relatively easy to grow, can be grown as part of multi-cropping systems and can be used as food and fibre (Da-costa-Rocha et al., 2014). In China the seeds are used for their oil and the plant is used for its medicinal properties, while in West Africa the leaves and powdered seeds are used in meals (Da-costa-Rocha et al., 2014). Additionally, it is used in the pharmaceutical and food industries (Da-costa-Rocha et al., 2014).
A limited number of reviews on H.sabdariffa have been conducted. Only one detailed review on the phytochemical, pharmacological and toxicological properties of H.sabdariffa ( Ali et al., 2005) and two more focused, later reviews are available: One on the effectiveness of H.sabdariffa in the treatment of hypertension ( Wahabi et al., 2010) and another on the treatment of hypertension and hyperlipidemia ( Hopkins et al., 2013).
1.1.1. Botanical description
The genus Hibiscus (Malvaceae) includes more than 300 species of annual or perennial herbs, shrubs or trees (Wang et al., 2012). H.sabdariffa (syn.: Abelmoschus cruentus (Bertol.) Walp., Furcaria sabdariffa Ulbr., Hibiscus cruentus Bertol., Hibiscus fraternus L., Hibiscus palmatilobus Baill. and Sabdariffa rubra Kostel ( The Plant list, 2010) is commonly known as roselle, hibiscus, Jamaica sorrel or red sorrel (English) and in Arabic, karkadeh ( Ali et al., 2005 ; Ross, 2003). Its native distribution is uncertain, some believe that is from India or Saudi Arabia ( Ismail, Ikram, and Nazri, 2008), while Murdock ( Murdock, 1959) showed evidence that H.sabdariffa was domesticated by the black populations of western Sudan (Africa) sometime before 4000 BC. Nowadays, it is widely cultivated in both tropical and subtropical regions (Morton, 1987 and USDA, 2007) including India, Saudi Arabia, China, Malaysia, Indonesia, The Philippines, Vietnam, Sudan, Egypt, Nigeria and México (Chewonarin et al., 1999; Dung et al., 1999; Eslaminejad and Zakaria, 2011; Ismail et al., 2008; Mahran et al., 1979; Rao, 1996; Sharaf, 1962 and Yagoub Ael et al., 2004).
There are two main varieties of H.sabdariffa, the first being H.sabdariffa var. altissima Wester, cultivated for its jute-like fibre and the second is H.sabdariffa var. sabdariffa. The second variety includes shorter bushy forms, which have been described as races: bhagalpuriensi, intermedius, albus and ruber. The first variety has green, red-streaked, inedible calyces, while the second and third race have yellow-green edible calyces (var. ruber) and also yield fibre (Morton, 1987).
H.sabdariffa var. sabdariffa ruber is an annual, erect, bushy, herbaceous subshrub that can grow up to 8 ft (2.4 m) tall, with smooth or nearly smooth, cylindrical, typically red stems. The leaves are alternate, 3 to 5 in (7.5–12.5 cm) long, green with reddish veins and long or short petioles. The leaves of young seedlings and upper leaves of older plants are simple; lower leaves are deeply 3 to 5 or even 7 lobed; the margins are toothed. Flowers, borne singly in the leaf axils, are up to 5 in (12.5 cm) wide, yellow or buff with a rose or maroon eye, and turn pink as they wither at the end of the day. At this time, the typically red calyx, consisting of 5 large sepals with a collar (epicalyx) of 8 to 12 slim, pointed bracts (or bracteoles) around the base, begins to enlarge, becomes fleshy, crisp but juicy, 1 1/4 to 2 1/4 in (3.2–5.7 cm) long and fully encloses the velvety capsule, 1/2 to 3/4 in (1.25–2 cm) long, which is green when immature, 5-valved, with each valve containing 3 to 4 kidney-shaped, light-brown seeds, 1/8 to 3/16 in (3–5 mm) long and minutely downy. The capsule turns brown and splits open when mature and dry. The calyx, stems and leaves are acid and closely resemble the cranberry (Vaccinium spp.) in flavour (Morton, 1987; Ross, 2003).