Table 2.

Biological activities of Hibiscus sabdariffa calyxes by in vitro tests and animal models.

Biological Activity	Type of Extract	Concentration/Dose	Model Assay	Main Results	Ref.
In vitro
Antioxidant	Water-methanol-acetone	NI	DPPH• and ABTS+ scavenging and FRAP	Extracts exhibited antioxidant properties	[35]
	Decoction and cold infusions	NI	Briggs–Rauscher oscillating reaction	Beverages exhibited antioxidant properties	[55]
Antihypertensive	Anthocyanin-rich fraction	84.5 µg/mL	ACE inhibitory assay	Fraction exhibited ACE inhibitory activity in a dose-dependent response	[34]
Vasorelaxant	Hexane-ethyl acetate-methanol	0.01 to 2 mg/mL	Rat aorta tissue	Fractions showed vasorelaxant effects by inhibition of Ca+ influx	[57]
Antidiabetic	Aqueous	IC50 of 25.2 and 187 µg/mL, respectively	α-amylase and α-glucosidase inhibition assay	The extract exhibited higher α-amylase inhibitory activity than α-glucosidase	[56]
Cardioprotective	Aqueous	7 to 500 µg/mL	Doxorubicin-induced cytotoxicity in rat heart-derived myoblast H9c2 cardiac myocyte cells	The extract exhibited a protective effect on cardiomyocytes, increasing cell viability and decreasing cell apoptosis	[58]
Antibacterial	Aqueous-methanolic	20 mg/L	Staphylococcus aureus, Escherichia coli, Klebsiellapneumoniae, and Bacillus cereus	The extract exhibited potent antimicrobial activity against Gram-negative bacteria	[59]
Antiviral	Aqueous decoction	100 mg/mL	Feline calicivirus, murine norovirus, and hepatitis A virus	Extracts showed antiviral activity to undetectable levels	[60]
Antiproliferative	Methanolic	0.2 to 1 mg/mL	Murine melanoma cell line (B16-F1) and human umbilical vein endothelial cells	Extract inhibits melanoma cell growth, migration, and tube formation in a dose-dependent response	[8]
Cytotoxic	Aqueous	0.05 to 0.5 mg/mL	Human breast cancer (MCF-7) cell line	The extract showed selective cytotoxic activity in a dose-dependent manner	[61]
In vivo
Neuroprotective	Aqueous decoction	500 mg/kg bw for 24 days before BCCAO	Ischemic brain injury-induced adult male Wistar rats	The extract showed protective effects against neuronal damage induced by BCCAO	[62]
	Ethanolic	200 to 500 mg/kg bw	Cypermethrin-induced oxidative stress in mice Mus musculus	The extract showed protective effects against toxicity induced by cypermethrin	[71]
Sedative	Maceration in hot water	100 to 400 mg/kg bw	Apomorphine-induced stereotypic behavior test using Swiss albino mice	HSE significantly reduced the exploratory behavior in mice, similar to diazepam	[63]
Antianxiety	Ethyl acetate fractions	5 to 30 mg/kg bw	Elevated plus-maze rat model	HS fraction reduced anxiety at low concentrations	[64]
Antidepressant	Ethyl acetate fractions	5 to 30 mg/kg bw	Porsolt’s forced swim test in rats	HS fraction exhibited antidepressant properties at doses of 20 mg/kg	[64]
Hepatoprotective	Aqueous extract	100 to 200 mg/kg bw	Wistar rats injected with 2,4-dinitrophenylhydrazine (DNPH)	The extract inhibited the toxicity of DNPH in a dose-dependent response similar to the control drug	[65]
Cardioprotective	Polyphenol-rich extract	100 mg/kg bw	Hyperglycemia-induced cardiac oxidative stress rats	The extract ameliorated oxidative stress damage in diabetic heart	[32]
Antihyperinsulinemic	Aqueous	50 to 200 mg/kg bw	High fructose diet-induced insulin resistance rats	The extract showed a similar effect to metformin, an oral antidiabetic drug	[66]
Antidiabetic	Aqueous	30 mg/mL	Alloxan-induced diabetic rat	The extract showed hypoglycemic and antioxidant effects	[72]
Anti-obesity	HS by-products	10 g/100 g HF/HFr diet	HF/HFr-induced rats	HS by-products reduced adipocyte hypertrophy, insulin resistance, and hepatic steatosis	[67]
Antihypertensive	Aqueous	6 mg/mL bw	Salt hypertensive-induced rats	The extract attenuated the development of salt-induced hypertension	[73]
Anti-inflammatory	Methanolic	100 to 400 mg/kg bw	Paw edema-induced rat	The extract significantly reduced the paw size edema in a dose-dependent manner in less time than aspirin	[68]
Hypolipidemic	Aqueous	500 to 1000 mg/kg bw	Hypercholesterolemic rats	The extract exhibited hypolipidemic effects in a dose-dependent response	[74]
Renal function improvement	Aqueous	2 g/L	Metabolic syndrome-induced rats	The extract decreased oxidative stress and promoted normal renal function	[30]
Anti-ulcer	Aqueous	100 to 800 mg/kg bw	Indomethacin-induced gastric ulcer rats	The extract exhibited a protective effect against induced gastric ulcer	[70]
Antianemic	Aqueous	200 mg/kg bw	Healthy rats	The extract improved hematological parameters	[69]

NI: no information; BW: body weight; DPPH^•: 2,2-diphenyl-1-picrylhydrazyl radical; ABTS⁺: 2,2′-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid); FRAP: ferric reducing antioxidant power; BCCAO: bilateral common carotid artery occlusion; HF/HFr: high-fat high fructose diet.