Hibiscus Acid and Chromatographic Fractions from Hibiscus Sabdariffa Calyces: Antimicrobial Activity against Multidrug-Resistant Pathogenic Bacteria.

The main aim of this study was to determine and compare the antimicrobial effect of hibiscus acid and a commercial 0.12% (w/v) chlorhexidine mouthrinse against Streptococcus mutans, Streptococcus sanguinis, Capnocytophaga gingivalis, and Staphylococcus aureus, and to determine the effect on bacterial cell membrane permeability and the toxicity of hibiscus acid in a mouse model. Hibiscus acid was obtained from acetone extract of Hibiscus sabdariffa calyces. Chlorhexidine (0.12% w/v) mouthrinse was purchased from a local pharmacy. The antimicrobial activity of hibiscus acid and mouthrinse were determined using the gel diffusion technique. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the solutions were determined using the broth dilution method. The effect on bacterial cell membrane permeability of hibiscus acid and mouthrinse was determined by crystal violet assay. The toxicity of hibiscus acid was investigated in a mouse model (registration number: UAEH2019-A1-S-8288). Hibiscus acid and mouthrinse showed antibacterial activity against all oral pathogenic bacteria. However, hibiscus acid showed a lower antibacterial effect compared with chlorhexidine mouthrinse. The MIC and MBC for hibiscus acid were 3 and 5 mg/mL, respectively, and was between 30 and 50 μg/mL for mouthrinse. The crystal violet test results indicate that hibiscus acid and mouthrinse alter the permeability of the bacterial membrane. Finally, hibiscus acid did not show toxicity in mouse studies.

The antibacterial effect of chloramphenicol, hibiscus acid, and a mixture of hibiscus acid and chloramphenicol against antibiotic-resistant enterohemorrhagic Escherichia coli (EHEC) and Salmonella Typhimurium (ST) was determined in Caesarean-Derived (CD)-1 mice. Hibiscus acid was isolated from Hibiscus sabdariffa calyces. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of chloramphenicol (CH), hibiscus acid (HA), and mixtures of HA/CH were determined for EHEC and ST. 11 groups of six mice each were formed. Four groups were inoculated orally with 4 log10 Colony forming units (CFU) of ST, four groups were inoculated with 4 log10 CFU of EHEC, and the remaining three groups were not inoculated. Six hours post inoculation, the mice in some groups received, via the oral route, solutions of hibiscus acid (7 mg/mL), chloramphenicol (82 µg/mL), a mixture of HA/CH (5.7 mg/mL HA and 4 µg/mL CH), or isotonic saline solution. The MIC and MBC values were between 7 and 5 mg/mL for hibiscus acid, between 17.6 and 82 µg/mL for chloramphenicol, and between 4.2 mg/mL/0.3 µg/mL and 5.7 mg/mL/0.4 µg/mL (concentration of hibiscus acid/concentration of chloramphenicol) or HA/CH. EHEC and ST were not detected in the feces of mice that were administered hibiscus acid alone or in mixture with chloramphenicol. By contrast, pathogens were isolated from the feces of untreated mice and those treated with chloramphenicol alone throughout the study.

The antimicrobial effect of hibiscus acid (HA) alone and in combination with nalidixic acid (NA) on multi-antibiotic-resistant Shiga-like toxin-producing Escherichia coli (STEC) and Salmonella Typhimurium (ST) was evaluated in CD-1 mice. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for NA and HA were determined against both STEC and ST. Fifteen sets of 6 mice each were utilized: 6 groups were exposed orally to 5 log10 colony forming units of a pool of 3 ST strains, another 6 were exposed to a pool of STEC; and 3 acted as controls. Six hours post-inoculation, specific mice groups received either oral solutions containing HA (2 and 7 mg/mL), or NA (20 and 250 µg/mL), or HA/NA (2 mg/mL HA and 20 µg/mL NA), or isotonic saline. All mice were euthanized on day 5 post infection, and tissues were collected to analyze the numbers of bacteria. The study determined the MIC and MBC of 7 mg/mL HA; 150 and 250 µg/mL of NA; and two concentrations of HA/NA (1 mg/mL/5 µg/mL and 2 mg/mL/20 µg/mL). Mice that were infected and treated with HA at 7 mg/mL or with HA/NA (2 mg/mL/20 µg/mL) did not have STEC or ST in their fecal samples or in the tissues. However, the pathogens were present in the stool and tissues of infected and untreated mice, and those infected and exclusively treated with NA250, NA20, or HA2 mg/mL. HA is an alternative for the treatment against antibiotic-resistant pathogenic bacteria.

Hibiscus sabdariffa L. (HS) has a long history of edible and medicinal uses. In this study, the biological activities of the extracts, chromatographic fractions, and hibiscus acid obtained from HS were evaluated for their potential bioactivities. Their ability to promote extracellular matrix synthesis in skin fibroblasts was evaluated by enzyme-linked immunosorbent assays. Their anti-inflammatory activity was evaluated in a nitric oxide (NO)–Griess inflammatory experiment. Furthermore, hibiscus acid was found to have a strong anti-oxidative stress effect through the establishment of an oxidative stress model induced by hydrogen peroxide. Several assays indicated that hibiscus acid treatment can effectively reduce extracellular adenosine triphosphate (ATP) secretion and carbonyl protein production, as well as maintain a high level of reduced/oxidized glutathione (GSH/GSSG) in skin cells, thus providing a possible mechanism by which hibiscus acid can counter antioxidative stress. The present study is the first to explore the reversing skin aging potential and the contributory component of HS.

Weexamined the antibacterial efficacy ofstreptomycin, hibiscus acid, and their combination against multidrug-resistant Shiga-toxin-producing Escherichia coli (STEC) and Salmonella Typhimurium inmice. Wedetermined the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for streptomycin, hibiscus acid, and their combination against STEC and Salmonella. Fifteen sets ofsix mice ineach set were utilised: six groups were orally exposed to4log10 colony forming units (CFUs) ofS.Typhimurium and another six toSTEC, and three acted asthe controls. Six hours post-inoculation, specific groups ofmice received either oral solutions containing hibiscus acid at5 and 7mg/ml; streptomycin at50 and 450μg/ml; hibiscus acid/streptomycin (5mg/ml hibiscus acid and 50μg/ml streptomycin); orisotonic saline. The study determined the MIC and MBC of7mg/ml ofhibiscus acid; 300 and 450μg/ml ofstreptomycin; and two concentrations ofhibiscus/streptomycin (3mg/ml/ 20μg/ml and 5mg/ml/ 50μg/ml). Interestingly, the mice that were infected and subsequently treated with hibiscus acid at7mg/ml alone orin conjunction with streptomycin did not have either STEC orSalmonella intheir faecal samples, and none ofthe mice died. Incontrast, the untreated mice and those exclusively treated with streptomycin had the pathogens present intheir stool, leading tothe mortality ofall the subjects.

ABSTRACTThe objective was to evaluate the antimicrobial effects and possible mechanisms of action of extracts of Hibiscus sabdariffa calyxes and hibiscus acid (AH) on Campylobacter jejuni. The antimicrobial effect of extracts of H. sabdariffa calyxes (obtained with water, acetone, methanol, and ethanol) was evaluated alone and in a mixture with antibiotics using the paper disk technique. Possible damage to the membrane through permeability modification, leakage of genetic material and proteins, modification of zeta potential (ζ), electrophoretic mobility, pore formation, and the effect on biofilm formation was also investigated. The study found that extracts from H. sabdariffa calyxes, particularly the acetone extract (AE) and AH, effectively inhibited C. jejuni by damaging its membrane, causing leakage of genetic material and proteins, and altering zeta potential (ζ) and electrophoretic mobility. Both AE and AH also disrupted biofilm formation and induced membrane porosity. However, no synergistic effect was observed when combined with antibiotics. The findings suggest that these extracts could be potential alternatives to antibiotics for combating antibiotic‐resistant C. jejuni.

Hibiscus acid from Hibiscus sabdariffa (Malvaceae) has a vasorelaxant effect on the rat aorta

The utilization of food as a therapeutic measure for various ailments has been a prevalent practice throughout history and across different cultures. This is exemplified in societies where substances like Hibiscus sabdariffa have been employed to manage health conditions like hypertension and elevated blood glucose levels. The inherent bioactive compounds found in this plant, namely, delphinidin-3-sambubioside (DS3), quercetin (QRC), and hibiscus acid (HA), have been linked to various health benefits. Despite receiving individual attention, the specific molecular targets for these compounds remain unclear. In this study, computational analysis was conducted using bioinformatics tools such as Swiss Target Prediction, ShinnyGo 0.77, KEGG, and Stringdb to identify the molecular targets, pathways, and hub genes. Supplementary results were obtained through a thorough literature search in PubMed. DS3 analysis revealed potential genetic alterations related to the metabolism of nitrogen and glucose, inflammation, angiogenesis, and cell proliferation, particularly impacting the PI3K-AKT signaling pathway. QRC analysis demonstrated interconnected targets spanning multiple pathways, with some overlap with DS3 analysis and a particular focus on pathways related to cancer. HA analysis revealed distinct targets, especially those associated with pathways related to the nervous system. These findings emphasize the necessity for focused research on the molecular effects of DS3, QRC, and HA, thereby providing valuable insights into potential therapeutic pathways.

Bioavailability of bioactive compounds in Hibiscus sabdariffa beverage as a potential anti-inflammatory

Selective separation of hibiscus acid from Roselle extracts by an amino-functionalized Metal Organic Framework

To determine and compare the antimicrobial effect of Hibiscus sabdariffa calyx extracts, six types of commercial mouthwashes, and chlorhexidine on Streptococcus mutans, Streptococcus sanguinis, Capnocytophaga gingivalis, and Staphylococcus aureus. Two varieties of H. sabdariffa cultivated in Mexico were used. Aqueous, methanolic, ethanolic, acetonic, and ethyl acetate extracts were obtained from H. sabdariffa calyces. Six different types of mouthwash (Astringosol®, Colgate plax-ice-infinity®, Crest pro-health®, Dental max®, Equate®, and Listerine zero®) and chlorhexidine (0.12%) were purchased at a pharmacy. The antimicrobial activity of the H. sabdariffa calyx extracts, mouthwashes, and chlorhexidine was determined by the agar disc diffusion technique. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of all solutions were determined by the broth dilution method and the pour plate technique, respectively. Also, the effect of H. sabdariffa extracts and chlorhexidine on permeability of the bacterial membrane was determined by the violet crystal assay. All H. sabdariffa calyx extracts and chlorhexidine showed antibacterial activity against all oral pathogenic bacteria. The mouthwashes showed lower antibacterial effect than H. sabdariffa extracts and chlorhexidine. Dental max showed no antibacterial effect. The MICs and MBCs, respectively, for H. sabdariffa extracts were between 5-20 and 10-20 mg/mL; and for chlorhexidine, between 3-4 and 3-5 mg/mL. For the Listerine®, the MIC and MBC values were between 20-25 and 25-33 mg/mL, respectively. The results of the crystal violet test indicate that H. sabdariffa calyx extracts and chlorhexidine alter the permeability of the bacterial membrane. All H. sabdariffa extracts and chlorhexidine showed significantly greater antimicrobial effect than mouthwashes. This is the first report in which the antimicrobial effect of the H. sabdariffa calyx extracts, mouthwashes, and chlorhexidine is compared.

The persistent dissemination of resistant bacterial strains is a grave contemporary global impediment in hospital-acquired infections which needs to be mitigated with immediate effect. In particular, infections from pathogenic multidrug-resistant (MDR) Gram-positive bacteria (like Enterococcus faecalis) which are resistant to conventional antibiotic therapy are attracting immediate global attention. Here we report the synthesis of nanoscale hydroxyapatites (HAPs), which are the well known biomimetic ceramic material having needle shaped morphologies. We have encapsulated vancomycin (VAN) within these nanoparticles and have conjugated the targeting ligand (folic acid) by a facile synthesis process in order to enhance the therapeutic efficacy against MDR E. faecalis. These functionalised HAPs are thoroughly characterised by employing field emission scanning electron microscopy (FESEM), powder x-ray diffraction (PXRD), ultraviolet–visible spectroscopy (UV-Vis) and dynamic light-scattering (DLS) techniques. Our results suggest that these functionalised HAPs could successfully transport vancomycin across the cell wall of MDR E. faecalis through endocytosis. The determination of selective antibacterial activity has been envisaged with the help of extensive in-vitro assays like the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and the generation of reactive oxygen species (ROS). This study vividly establishes that this folic acid conjugated HAPs are promising antibacterial agents against MDR E. faecalis and related pathogenic resistant bacterial strains.

Sorghum bicolor and Hibiscus sabdariffa are common plants whose uses have not been fully utilized. However, the two plants are rich in anthocyanins which make them a good dye substrate. Therefore, this study assessed the extraction and acceptability ofdyestuffs from Sorghum bicolor leaves and Hibiscus sabdariffa calyxes. Organoleptic Attributes Acceptability of Treated Fabric Evaluation (OAATFE) was used to evaluate the 5 coded samples treated with the dye extracts and the composites developed, which were SXB1, HYS4, ABS6, ASH8 and ABH3. Questionnaire was used to gather information on the acceptability and utilization of the two dye extract by women in five communities randomly selected in Moro local government area. The result of the findings revealed that characterization of Sorghum bicolor leaves and Hibiscus sabdariffa calyxes shows that different anthocyanins are the major colour bearing compound. All the samples are acceptable with fabric dyed, with dye extracted from Hibiscus sabdariffa calyxes is more acceptable. Additionally, in terms of organoleptic acceptability, there exist significant differences between the samples with Hibiscus sabdariffa calyxes having the highest acceptability. Thus, the study concludes that Sorghum bicolor leaves and Hibiscus sabdariffa calyxes are good sources of natural dyes as they are rich in colour yielding compounds (anthocyanin). Hence, dye extracts from Sorghum bicolor leaves and Hibiscus sabdariffa calyxes can be applied in dyeing cotton fabric. However the study recommends the use of extract of 100% Hibiscus sabdariffa for women in Moro local government area as a means of poverty alleviation.

Zobo leaves, also known as Roselle leaves are leaves of the Malvaceae plant Hibiscus sabdariffa, they are a common culinary ingredient as well as a traditional medicine in many countries including their role in treating various ailments and promoting overall health. The biological properties of the leaves of this plant have been studied and found to be of benefit to general improvement of health such biological properties as anti-inflammatory, anti-diabetic, anti-hypertensive, anti-cancer effects, potency against respiratory infections, skin diseases, and gastrointestinal disorders etcetera. These all stem from the bioactive components (anthocyanins, polyphenols, flavonoids, protocatechuic acid, malic acid, ascorbic acid, hibiscus acid contained in it. Our review focuses on these biological properties of Hibiscus sabdariffa and the bioactive compounds that are responsible for them. The nature, proximate composition including nutrient and mineral content, physicochemical properties and traditional uses of the plant according to different cultures are also included in our work. Finally, the importance of further research to fully understand the pharmacology and potential therapeutic applications of Roselle leaf and its bioactive compounds are highlighted.

The occurrence of multidrug-resistant pathogenic bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant Acinetobacter baumannii (MDRAB), extended-spectrum β-lactamase (ESBL) Escherichia coli, and Pseudomonas aeruginosa, has become a serious problem in animals and public. The objective of this study was to identify and isolate lactic acid bacterial (LAB) strains from the intestinal tracts of pigs and feces of dogs and then characterize them as potential probiotics with antimicrobial activity against multidrug-resistant pathogenic bacteria. In a preliminary isolation screening, 45 of 1167 isolated LAB strains were found to have anti-S. aureus ATCC 27,735 activity. Using 16S rDNA and 16S-23S rDNA intergenic spacer region (ISR) sequences, five of these isolates were further identified as Lactobacillus animalis 30a-2, Lactobacillus reuteri 4-12E, Weissella cibaria C34, Lactococcus lactis 5-12H, and Lactococcus lactis 6-3H. Antimicrobial substance assays suggest that the L. lactis 5-12H, L. lactis 6-3H, L. animalis 30a-2, L. reuteri 4-12E, and W. cibaria C34 strains might produce bacteriocins and hydrogen peroxide (H2O2) as antimicrobial substances. The L. animalis 30a-2 and W. cibaria C34 strains were further characterized for probiotic properties and shown to have high acid and bile salt tolerance. Additionally, they have broad antimicrobial spectra, and can significantly repress the growth of all of the tested strains of MRSA isolates, some MDRAB, ESBL E. coli, and P. aeruginosa isolates, along with food-borne pathogenic bacteria such as Bacillus cereus ATCC 11778, Listeria monocytogens ATCC 19111, Salmonella spp., Shigella spp., and Yersinia enterocolitica BCRC 12986. This is the first report of H2O2-producing L. animalis 30a-2 and W. cibaria C34 isolated from the intestinal tracts of pigs and feces of dogs that have good antimicrobial activity against multidrug-resistant and food-borne pathogenic bacteria and have excellent probiotic properties.