Toxicity studies of the water extract from the calyces of Hibiscus sabdariffa L. in rats

Hibiscus Sabdariffa L. Extract as a Natural Additive in Food Packaging Biodegradable Films to Improve Antioxidant, Antimicrobial, and Physicochemical Properties

In this study, biodegradable active films were prepared from potato starch and polyvinyl alcohol at different proportions, mixed with acetone extract of Hibiscus sabdariffa L. (HS) and using glycerol as a plasticizer. Functional properties, antimicrobial, and antioxidant capacity were evaluated. Potato starch films with a proportion of polyvinyl alcohol up to 50% and HS extract had significant antioxidant capacity and antibacterial effect against most of the analyzed strains. Adding polyvinyl alcohol (PVOH) and HS extract improved the mechanical performance and reduced water vapor permeability of the materials. The active biobased films with HS extract presented good physicochemical, antimicrobial, and antioxidant properties. These materials are considered as suitable for food packaging, and the active compounds in the roselle extract are a natural antibacterial option for the food area. The materials based entirely on biodegradable products are an excellent alternative when developing and marketing biobased materials, minimizing the environmental impact of food packaging.

Hibiscus, Rooibos, and Yerba Mate for Healthy Aging: A Review on the Attenuation of In Vitro and In Vivo Markers Related to Oxidative Stress, Glycoxidation, and Neurodegeneration

The world is currently undergoing a demographic change towards an increasing number of elderly citizens. Aging is characterized by a temporal decline in physiological capacity, and oxidative stress is a hallmark of aging and age-related disorders. Such an oxidative state is linked to a decrease in the effective mechanisms of cellular repair, the incidence of post-translational protein glycation, mitochondrial dysfunction, and neurodegeneration, just to name some of the markers contributing to the establishment of age-related reduction-oxidation, or redox, imbalance. Currently, there are no prescribed therapies to control oxidative stress; however, there are strategies to elevate antioxidant defenses and overcome related health challenges based on the adoption of nutritional therapies. It is well known that herbal teas such, as hibiscus, rooibos, and yerba mate, are important sources of antioxidants, able to prevent some oxidation-related stresses. These plants produce several bioactive metabolites, have a pleasant taste, and a long-lasting history as safe foods. This paper reviews the literature on hibiscus, rooibos, and yerba mate teas in the context of nutritional strategies for the attenuation of oxidative stress-related glycoxidation and neurodegeneration, and, here, Alzheimer’s Disease is approached as an example. The focus is given to mechanisms of glycation inhibition, as well as neuroprotective in vitro effects, and, in animal studies, to frame interest in these plants as nutraceutical agents related to current health concerns.

Toxicity assessment of sub-acute and sub-chronic oral administration and diuretic potential of aqueous extract of Hibiscus sabdariffa calyces

Background

Food and herbal usage of Hibiscus sabdariffa (HS) is attaining improved global relevance and acceptance without recourse to its potential toxic effects. This study investigated the safety profile of acute, sub-acute, sub-chronic administrations and diuretic potential of aqueous extract of Hibiscus sabdariffa calyces (AEHSC).

Method

Acute oral toxicity, sub-acute and sub-chronic toxicity as well as diuretic studies were carried out on HS. A total of 20 Wistar rats were used for each toxicity study and assigned into four groups of five rats. The extract was administered as a single daily dose of 125, 250 and 500 mg/kg body weight (bwt) for 28 and 90 days respectively. To evaluate diuretic activity, 25 rats were divided into five groups of five rats and administered normal saline, hydrochlorothiazide 10 mg/kg, AEHSC 67.5, 125 and 250 mg/kg via the oral route. Urine sample was collected after 18 h, volume measured and concentration of electrolytes analyzed. The hematological and biochemical parameters were evaluated as well as the histopathology of kidney and liver.

Results

The acute oral toxicity was found to be >2000 mg/kg. AEHSC did not alter concentration of WBC, MCV, MCHC, lymphocyte as well as total and direct bilirubin in the sub-acute study. However, AEHSC significantly (p < 0.05) increased total protein, albumin, globulin, Na⁺, Cl⁻, HCO₃^- and platelet levels, while levels of uric acid, creatinine, K⁺, RBC, Hb, total cholesterol, triglycerides, LDL-C, HDL-C and atherogenic index were decreased significantly (p < 0.05). In the sub-chronic study, AEHSC significantly (p < 0.05) increased the levels of globulin, urea, creatinine, MCH and atherogenic index. The concentrations of uric acid, WBC, platelets and HDL-C were significantly (p < 0.05) decreased. In both the sub-acute and sub-chronic studies, activities of ALP, ALT, AST, GGT and LDH in selected organs were altered without significant increase (P < 0.05) in activity of these enzymes in the serum. The AEHSC at all the doses showed remarkable diuretic activity during 18 h period comparable to hydrochlorothiazide. The extract also showed a non-dose-dependent increase in excretion of electrolytes. Histological analysis of sections of the liver and kidney for both sub-acute and sub-chronic studies showed normal histology comparable to the control group.

Conclusion

This study revealed AEHSC has some toxic effects in rats on sub-chronic administration. In addition, the extracts produced a significant diuretic activity. Hence, prolonged oral consumption of the extract may not be recommended.

Inhibition of HIV-1 Protease by Carpobrotus edulis (L.)

Carpobrotus edulis (L.) is a plant commonly found in the Eastern Cape Province of South Africa and is used for the general treatment of infections relating to the human immunodeficiency virus (HIV). HIV-1 protease plays an important role during HIV replication and maturation to its infectious form, and therefore inhibition of the enzyme is one of the main focus areas in drug development. The inhibitory effect of a water extract of C. edulis leaves against HIV-1 protease activity was determined using the SensoLyte® 520 HIV-1 protease assay fluorimetric kit and employing a HiLyte Fluor™488/QXL™520 fluorescence resonance energy transfer (FRET) peptide. Cytotoxicity of the extract towards HeLa Chang cell lines was determined using an in vitro MTT assay, and the phytochemical profile of the extract was determined with FT-IR and LC-MS. HIV-1 protease activity was inhibited 83.06% (IC₅₀ 1.6 mg/ml) (p < 0.0001) by the pepstatin A inhibitor control. Treatment with all C. edulis extract concentrations (16, 1.6, 0.16, and 0.016 mg/ml) inhibited HIV-1 protease activity significantly (p < 0.0001) in a typical dose response manner. With regards to cytotoxicity, the negative controls containing untreated HeLa Chang cells exhibited high formazan formation rates in contrast with the positive controls, containing curcumin, which reduced formazan formation significantly (p < 0.001), exhibiting cytotoxicity towards the cells. There was no significant (p > 0.05) difference in the formazan formation rates between the negative controls and 1, 0.5, 0.125, 0.065, 0.031, and 0.015 mg/ml plant extract, confirming no toxicity of C. edulis extracts towards HeLa Chang cells. Major functional phytochemical compounds identified included alcohols, phenols, alkanes, amines, carboxylic acids, and esters. LC-ESI-TOF/MS analysis revealed the putative identities of main compounds present in the aqueous leaves extract, including some that contribute to its anti-HIV-1 protease action.

Potential Application of Tetrapleura tetraptera and Hibiscus sabdariffa (Malvaceae) in Designing Highly Flavoured and Bioactive Pito with Functional Properties

Sorghum beer (pito) is an indigenous alcoholic beverage peculiar to northern Ghana and parts of other West African countries. It is overwhelmed with calories, essential amino acids (such as lysine, etc.), B-group vitamins, and minerals. In recent years, there has been a growing demand for highly flavoured yet functional pito in Ghana; however, the local producers lack the prerequisite scientific expertise in designing such products. We propose the utilization of Tetrapleura tetraptera (TT) and Hibiscus sabdariffa (HS) as cheap and readily available materials in designing functional flavoured pito. The addition of TT and HS would not alter the fermentation profile but rather augment the starter with nutrients, thus improving the fermentation performance and shelf life of the final pito. In vitro and in vivo studies provide substantive evidence of antioxidant, nephro- and hepato-protective, renal/diuretic effect, anticholesterol, antidiabetic, and antihypertensive effects among others of the TT and HS, hence enriching the pito with health-promoting factors and consequently boosting the health of the consumer. Herein, we summarise the phytochemical, biological, pharmacological, and toxicological aspects of TT and HS as well as the technology involved in brewing the novel bioactive-flavoured pito. In addition, we also report the incidence of heavy metal in conventional pito.

Ethnomedicinal, Phytochemical and Ethnopharmacological Aspects of Four Medicinal Plants of Malvaceae Used in Indian Traditional Medicines: A Review

The ethnomedicinal values of plants form the basis of the herbal drug industry. India has contributed its knowledge of traditional system medicines (Ayurveda and Siddha) to develop herbal medicines with negligible side effects. The World Health Organization has also recognized the benefits of drugs developed from natural products. Abutilon indicum, Hibiscus sabdariffa, Sida acuta and Sida rhombifolia are ethnomedicinal plants of Malvaceae, commonly used in Indian traditional system of medicines. Traditionally these plants were used in the form of extracts/powder/paste by tribal populations of India for treating common ailments like cough and cold, fever, stomach, kidney and liver disorders, pains, inflammations, wounds, etc. The present review is an overview of phytochemistry and ethnopharmacological studies that support many of the traditional ethnomedicinal uses of these plants. Many phytoconstituents have been isolated from the four ethnomedicinal plants and some of them have shown pharmacological activities that have been demonstrated by in vivo and/or in vitro experiments. Ethnomedicinal uses, supported by scientific evidences is essential for ensuring safe and effective utilization of herbal medicines.