Antioxidant activity of leaf extracts from different Hibiscus sabdariffa accessions and simultaneous determination five major antioxidant compounds by LC-Q-TOF-MS

Comparison of Antioxidant Properties and Metabolite Profiling of Acer pseudoplatanus Leaves of Different Colors

Acer pseudoplatanus (maple) is a widely grown ornamental plant. In addition to its ornamental and ecological value, it also has potentially high economic value. It is a rich source of polyphenols and exhibits antioxidant activity. However, the relationship between polyphenol content and antioxidant activity in maple leaves of different colors (green, yellow, and red) has not yet been investigated. In this study, the total polyphenol (TP), total flavonoid (TFlav), tannin (TET), chlorophyll a and b (Chl a and b), total anthocyanin (TAN), and total carotene (TAC) contents in maple leaves of different colors were evaluated. Their antioxidant activities were determined based on the inhibition of lipid oxidation, DPPH scavenging, ferric ion-reducing antioxidant power, and iron-chelating abilities. The concentrations of TP, TET, TFlav, TAN, and TAC in red maple leaves were higher than those in green and yellow maple leaves. In addition, red maple leaves showed a higher antioxidant effect than the leaves of the other two colors. We observed that antioxidant activity was positively correlated with TP, TFlav, and TAN and negatively correlated with Chl a and b. Finally, we analyzed the metabolites of the different colored (i.e., green, yellow, and red) maple leaves using gas chromatography/mass spectrometry (GC/MS) and found that the metabolite profile significantly varied between the different colors. These results suggest that red leaves are a good source of polyphenols and antioxidants and have potential use in the development of functional foods and medicinal applications.

Oenanthe javanica Ethanolic Extract Alleviates Inflammation and Modifies Gut Microbiota in Mice with DSS-Induced Colitis

Oenanthe javanica, commonly known as water dropwort, has long been used to treat acute and chronic hepatitis, abdominal pain, alcohol hangovers, and inflammation in various traditional medicine systems in Asia. However, whether O. javanica has beneficial effects on colitis-induced intestinal damage remains elusive. This study tested the hypothesis that O. javanica has anti-inflammatory and antioxidant activities in mice with dextran sulfate sodium (DSS)-induced colitis. First, treatment of O. javanica ethanol extract (OJE) inhibited the production of inflammatory cytokines in lipopolysaccharide-affected macrophages. Second, in mice with DSS-induced colitis, OJE administration reduced pathological damage to the colon while alleviating weight gain and decreasing colon length, including inflammation and mucosal necrosis. In addition, OJE significantly (p < 0.01) restricted the activation of nuclear factor-κB (NF-κB) and the secretion of pro-inflammatory mediators and increased the expression of Nrf2-phase 2 antioxidant enzymes. The results of 16S rRNA gene sequencing workflows for taxonomic assignment analysis confirmed that the diversity (richness and evenness) of fecal microbiota was markedly elevated in the OJE group. OJE administration reduced the abundance of Proteobacteria including Escherichia and increased the abundance of the genus Muribaculum. These results suggested that OJE exerts beneficial effects on inflammation and gut microbial composition in a mouse model of colitis.

The effect of roselle leaf (Hibiscus sabdariffa L.) extract gel on wound healing

Roselle (Hibiscus sabdariffa L.) belongs to the genus Hibiscus with proven anti-inflammatory, antioxidant, and antimicrobial properties. Scientific evidence associated roselle content with bioactive compounds, such as phenolic acids, flavonoids, and anthocyanin. Most studies focused on their petals, while research on leaf extract on wound healing has never been done. This study aimed to assess the effect of roselle leaf extract on wound healing in rats. This was an experimental laboratory study with a posttest-only control group design. There were 30 rats divided into 5 groups: negative control, 5%, 10%, and 15% roselle leaf extract, and positive control (bioplacenton). The parameters assessed in this research were wound size and histological assessment. The data were analyzed using ANOVA. P<0.05 was considered statistically significant. Wound healing percentage and epithelial thickness in the 15% group were the largest (84.17%; 64.69 µm). The lowest value was recorded in placebo (64%; 36.33 µm). Meanwhile, wound healing percentage and epithelial thickness of rats in the 5% and 10% groups were 68.53%, 43,57 µm, and 78.11%, 56.49 µm, respectively. Finally, positive control had a 77.44% wound healing percentage and 49.7 µm epithelial thickness. There were no significant differences in wound healing and epithelial thickness among the groups. Roselle leaf extract at 15% concentration showed greater wound healing properties based on clinical and histological assessment. Although there were no statistically significant differences, roselle leaf showed an opportunity to be further investigated as a potential wound healing therapy.

Efficient green photocatalyst of silver-based palladium nanoparticles for methyle orange photodegradation, investigation of lipid peroxidation inhibition, antimicrobial, and antioxidant activity

Nanotechnology is an interdisciplinary study that has been developing worldwide in recent years and has a serious impact on human life. The fact that the nanoparticles of plant origin are clean, non-toxic, and biocompatible has enabled new fields of study. The Hibiscus sabdariffa (H. sabdariffa) plant has been attracted by scientists because of its impact on health and many other areas. The lipid peroxidation inhibiting activity, antioxidant properties, and antimicrobial properties of H. sabdariffa plant with Ag-Pd metal was ditermined. For the total phenolic component, gallic acid was used as the standard and quarcetin was used for the total flavonoid. The lipid peroxidation inhibition activity of Ag-Pd NPs in ethanol extract was found to be very well compared to the positive control (BHA). The lowest and highest concentrations of DPPH radical scavenging activity were 82.178-97.357%, whereas for BHA these values were found to be 84.142-94.142%. The highest concentration of Ag-Pd NPs at 200 μg/mL the DPPH radical quenching activity was higher than BHA. Ag-Pd NPs showed a good antimicrobial activity against certain pathogenic microorganisms such as Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, which are the causative agents of various diseases in humans. The photodegradation activity of Ag-Pd NPs also investigated against Methyl orange dye (MO) under sunlight irradiation for 120 min and was found to be as 67.88.

Phenolic Compounds from Leaves and Flowers of Hibiscus roseus: Potential Skin Cosmetic Applications of an Under-Investigated Species

The use of plant extracts in skin-care cosmetics is a modern trend due to their richness in polyphenols that act as anti-aging molecules. Hibiscus roseus is a perennial species naturalized in Italy, with beautiful soft pink flowers; its phenolic composition and biological activities have not been studied yet. The aim of this study was to characterize and quantify the phenolics and to evaluate the antioxidant, sun protection factor (SPF), and anti-collagenase activities of the ethanolic extracts of H. roseus leaves (HL) and flowers (HF). p-Coumaric, chlorogenic, and trans-ferulic acids derivatives as well as quercetin and kaempferol flavonoids were the main phenolic compounds detected. Catechin, epicatechin, kaempferol-3-O-rutinoside, kaempferol-3-O-glucoside, kaempferol-7-O-glucoside, tiliroside, oenin, and peonidin-3-O-glucoside were detected only in HF, while phloridzin was exclusive from HL, which also showed greater amounts of hydroxycinnamic acid derivatives. HF was richer in flavonoids and total phenolics, also exhibiting greater antioxidant capacity. The SPF and anti-collagenase activity of both extracts were similar and comparable to those of synthetic standards. The overall results demonstrate that H. roseus extracts are promising sources of bioactive phenolic compounds that could be potentially applied as anti-aging agents in skin-care cosmetics.

Enriching street-vended zobo (Hibiscus sabdariffa) drink with turmeric (Curcuma longa) to increase its health-supporting properties

Street-vended foods are cheap, readily available and have been currently identified as possible means for micronutrient fortification in an effort to prevent malnutrition in developing countries. The effect of enriching street-vended zobo drink (Hibiscus sabdariffa) with turmeric (Curcuma longa) was studied to assess the potential to increase health-supporting properties for its consumers. Two processing methods were tested: boiled turmeric root in zobo and addition of fresh turmeric paste to zobo in different concentrations. Vitamin C in turmeric-fortified zobo ranged from 496-725 μg per 100 mL, delphinidin-3-sambubioside from 52-69 mg per 100 mL, and cyanidin-3-sambubioside from 21-27 mg per 100 mL. Micronutrients ranged from 10.9-14 mg L^-1 and 2.19-2.67 mg L^-1 for iron and zinc, respectively. Folic acid, vitamin C, anthocyanins and iron showed the highest amounts in the 2% boiled turmeric zobo samples. Ferulic acid (0.16-2.03 mg per 100 mL), and chlorogenic acid (20-24 mg per 100 mL) did not show the same statistically significant improvement for 2% boiled turmeric-fortified zobo. The zobo samples with turmeric paste consistently had lower values of vitamins, polyphenols and minerals in comparison with the boiled turmeric-fortified zobo samples. Turmeric-fortified zobo can play a role in a healthy diet by its health-supporting properties. Consumption of a typical one serving of 500 mL (representative packaged bottle size of zobo drink by the street vendors in Nigeria) of turmeric-fortified zobo would contribute 63-88% DV and 18-23% DV of iron and zinc. Overall, fortification with boiled turmeric improves the antioxidant and nutritional quality of zobo, specifically regarding vitamin C, delphinidin-3-sambubioside and iron.

Phenolic Compounds in Extracts of Hibiscus acetosella (Cranberry Hibiscus) and Their Antioxidant and Antibacterial Properties

Hibiscus species are rich in phenolic compounds and have been traditionally used for improving human health through their bioactive activities. The present study investigated the phenolic compounds of leaf extracts from 18 different H. acetosella accessions and evaluated their biofunctional properties, focusing on antioxidant and antibacterial activity. The most abundant phenolic compound in H. acetosella was caffeic acid, with levels ranging from 14.95 to 42.93 mg/100 g. The antioxidant activity measured by the ABTS assay allowed the accessions to be classified into two groups: a high activity group with red leaf varieties (74.71–84.02%) and a relatively low activity group with green leaf varieties (57.47–65.94%). The antioxidant activity was significantly correlated with TAC (0.933), Dp3-Sam (0.932), Dp3-Glu (0.924), and Cy3-Sam (0.913) contents (p < 0.001). The H. acetosella phenolic extracts exhibited antibacterial activity against two bacteria, with zones of inhibition between 12.00 and 13.67 mm (Staphylococcus aureus), and 10.67 and 13.33 mm (Pseudomonas aeruginosa). All accessions exhibited a basal antibacterial activity level (12 mm) against the Gram-positive S. aureus, with PI500758 and PI500764 exhibiting increased antibacterial activity (13.67 mm), but they exhibited a more dynamic antibacterial activity level against the Gram-negative P. aeruginosa.

Insight into the molecular evidence supporting the remarkable chemotherapeutic potential of Hibiscus sabdariffa L

Hibiscus sabdariffa or roselle tea is popular around the globe for its antioxidant capability along with various other health benefits. Besides, it has uses in Ayurvedic and Chinese herbal medicines for the treatment of several diseases. However, the investigation for the anticancer potential of the plant began roughly in the last decade that emerged with encouraging results. Both crude extracts and pure compounds of the plant were reported to induce chemoprevention, selective cytotoxicity, cell cycle arrest, apoptosis, autophagy and anti-metastasis effects in varied types of human cancer cells. The plant contains a high quantity of polyphenolic compounds and at least two of them were proven to induce potent anticancer effects. Although, the molecular mechanism underlying the anticancer activity was roughly estimated in several studies. The present review aimed to assemble all ambiguous information to report the molecular evidence establishing the potent anticancer activity of Hibiscus sabdariffa and its implication for cancer therapy. This study suggests that Hibiscus sabdariffa is an ideal candidate to investigate its role as a herbal supplement for cancer prevention and treatment. With excellent safety and tolerability record, polyphenolic compounds from the plant need better designed clinical trials.

Polyphenol Profile and Antimicrobial and Cytotoxic Activities of Natural Mentha × piperita and Mentha longifolia Populations in Northern Saudi Arabia

New sources of polyphenols with anticancer, antioxidant, and antimicrobial properties in arid environments are critical for the development of alternative medicines and natural remedies. This study explored the polyphenol profiles and biological activities of methanolic leaf extracts from natural Mentha × piperita and Mentha longifolia populations in northern Saudi Arabia. Chromatographic analyses identified several polyphenols in M. × piperita including phenolic acids: rosmarinic acid (1547.6 mg/100 g DW (dry weight)), cryptochlorogenic acid (91.7 mg/100 g DW), and chlorogenic acid (69.4 mg/100 g DW), as well as flavonoids: naringin (328.8 mg/100 g DW) and cynaroside (162.8 mg/100 g DW). The major polyphenols in M. longifolia were: rosmarinic acid (781.6 mg/100 g DW), cryptochlorogenic acid (191.1 mg/100 g DW), p-coumaric acid (113.0 mg/100 g DW), m-coumaric acid (112.2 mg/100 g DW), and chlorogenic acid (63.8 mg/100 g DW). M. × piperita and M. longifolia leaf extracts had high antioxidant activities due to the major polyphenols (cynaroside, rosmarinic and cryptochlorogenic acids). M. × piperita had higher activities against different cancer cells than M. longifolia. Naringin, cryptochlorogenic acid, and rosmarinic acid had the highest activities against cancer cells. The leaf extracts had antibacterial effects against most bacteria species (Pseudomonas aeruginosa was most sensitive), which was attributed to the polyphenols. Antifungal activities were similarly broad (Aspergillus flavus was most sensitive) and attributed to naringin, cryptochlorogenic acid, and caffeic acid. Populations of M. × piperita and M. longifolia in Northern Riyadh may be a valuable source of natural biologically active compounds.

Phytochemical Analysis and Antimicrobial/Antioxidant Activity of Cynodon dactylon (L.) Pers. Rhizome Methanolic Extract

A proper use of medicinal plants requires accurate scientific information and understanding of their chemical constituents. The therapeutic effects in the plants are due to the chemical compounds therein. Cynodon dactylon (L.) Pers. of the family Poaceae is a perennial, pan-tropical species of grass which is a well-known traditional medicine and has a renowned position for treatment of many symptoms and diseases. The chemical composition, free radical scavenging activity, and antimicrobial properties of the methanolic extract of C. dactylon rhizomes against selected bacterial and fungal strains were investigated using disk-diffusion method. The results indicated that the major fatty acid structures of C. dactylon methanolic extract were palmitic acid (36.40%), oleic acid (28.26%), and linoleic acid (17.01%). Alpha-tocopherol (151.39 mg·kg−1) and sitosterol (3199.62 mg·kg−1) were the main tocopherols and sterols, respectively. According to the instrumental analysis, the total phenolic compounds of methanolic extract were equal to 917.08 mg·kg−1 and the main compound was hydroquinone (66.89%). Antioxidant activity of the methanolic extract at concentrations of 100–1000 ppm was 9.81–67.87%, which is significantly different from the 200 ppm synthetic antioxidant (BHT) with free radical scavenging activity equal to 48.93% (p<0.05). The antimicrobial study revealed that the methanolic extract of C. dactylon rhizomes was effective against all of the bacterial pathogens and the antibacterial activity increased with an increase in the concentration of extract. Therefore, the largest zone of inhibition was observed against Bacillus cereus (18.3 ± 0.4 mm) and Escherichia coli (16.8 ± 0.5 mm) at 1000 ppm. The highest resistance was observed with Pseudomonas aeruginosa (inhibition zone of 12.8 ± 0.15 mm). Methanolic extract at 200 ppm had no effect against fungus Aspergillus niger. However, at 1000 ppm concentration, an inhibition zone with a diameter of 14.4 ± 0.45 mm was formed.

Influence of Extraction Methods on Total Phenolic Content and Antioxidant Properties of Some of the Commonly Used Plants in Thailand

BACKGROUND AND OBJECTIVE

Several plants have been commonly used in Thailand for health improvement, but the phytochemical content and its bio-activities are not yet elucidated completely. The aim of this research was to study the influence of extraction method on total phenolic content (TPC) and antioxidant activity of representative plants such as Punica granatum, Hibiscus sabdariffa, leistocalyx operculatus (Roxb.) Merr., litoria ternatea Linn., Mulberry and Oryza sativa L. indica.

METHODOLOGY

The samples were subjected to different extraction procedures. The TPC and phenolic compounds were determined by Folin-Ciocalteu colorimetric assay and HPLC, respectively. The antioxidant capacity of the extracts was measured by 2, 2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and ferric reducing antioxidant power (FRAP) assays and ferrous ion (Fe2+) chelating assay.

RESULTS

The maximum TPC was observed in pomegranate peel (TTP) extract (0.1 M HCl: Ethanol extraction) and low TPC was recorded in aqueous extract of butterfly pea flower (BP) samples. The high content of protocatechuic, p-hydroxybenzoic acid were observed in pomegranate seed and seed coat (TTS). Gallic and syringic acids were found to be rich in pomegranate peel (TTP) and flower of butterfly pea (BP), respectively. Roselle flower samples (KJ) showed high content of chlorogenic, p-coumaric and caffeic acids.

CONCLUSION

The maximum antioxidant activity was observed in extracts obtained by 0.1 M HCl: Ethanol extraction methods, especially pomegranate peel exhibited high free radical scavenging activity compared to that of the other samples. The results strongly revealed that the extraction method greatly influences the phytochemical content and bioactivity and strongly recommends that any plant samples, intended to study, must undergo several extraction processes to reveal the actual phytochemical content.

Microwave-assisted extraction for Hibiscus sabdariffa bioactive compounds

H. sabdariffa has demonstrated positive results against chronic diseases due to the presence of phytochemicals, mainly phenolic compounds. The extraction process of bioactive compounds increases the efficient collection of extracts with high bioactivity. Microwave-Assisted Extraction (MAE) constituted a "green technology" widely employed for plant matrix. In this work, the impact of temperature (50-150 °C), composition of extraction solvent (15-75% EtOH) and extraction time (5-20 min) on the extraction yield and individual compounds concentrations were evaluated. Furthermore, the characterization of 16 extracts obtained was performed by HPLC-ESI-TOF-MS. The results showed that 164 °C, 12.5 min, 45% ethanol was the best extraction condition, although glycoside flavonoids were degraded. Besides that, the optimal conditions for extraction yield were 164 °C, 60% ethanol and 22 min. Thus, temperature and solvent concentration have demonstrated to be potential factors in MAE for obtaining bioactive compounds from H. sabdariffa.

Improvement of dermal parameters in aged skin after oral use of a nutrient supplement

Purpose

Skin aging is a progressive and degenerative process caused by a decrease in the physiological functions of the skin tissue. In addition, environmental factors as well as concomitant diseases and lifestyle (nutrition, sedentary lifestyle, smoking, etc) negatively impact the aging process. An association between oral administration of collagen peptides combined with vitamin C and extracts of Hibiscus sabdariffa and Aristotelia chilensis (Delphynol^®) (Eximia Firmalize Age complex^®) on dermal thickness was studied and the improvement in aging signs was evaluated.

Patients and methods

Female adult patients received an oral nutritional supplement containing collagen peptides, vitamin C, H. sabdariffa, and A. chilensis (Delphynol) in a sachet and were instructed to consume 1 sachet diluted in 200 mL of water once daily for 12 weeks. They were evaluated clinically, by high frequency ultrasound and cutometry.

Results

There was a significant improvement of firmness and elasticity and an increase in dermal thickness by ultrasound after 3 months of use.

Conclusion

The association of collagen peptides, vitamin C, H. sabdariffa and A. chilensis (Delphynol) could improve the signs of dermal skin aging.

Antioxidative and Anti-Melanogenic Activities of Bamboo Stems (Phyllostachys nigra variety henosis) via PKA/CREB-Mediated MITF Downregulation in B16F10 Melanoma Cells

Phyllostachys nigra var. henosis, a domestic bamboo species, has been attracting much attention; its bioactive compounds (especially in the leaf) show antioxidant, anti-inflammatory, and anti-obesity activities. Little information is available on the antioxidative and anti-melanogenetic activities of the bioactive compounds in bamboo stems. The anti-melanogenic and antioxidative activities of the EtOAc fraction (PN3) of a P. nigra stem extract were investigated in a cell-free system and in B16F10 melanoma cells. PN3 consisted of a mixture of flavonoids, such as catechin, chlorogenic acid, caffeic acid, and p-coumaric acid. The antioxidant activity (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS)), and hydroxyl radical scavenging) was evaluated, as well as the inhibition of reactive oxygen species (ROS) produced by the Fenton reaction. PN3 showed in vitro tyrosinase inhibition activity with the half maximal inbihitory concentration (IC₅₀) values of 240 μg/mL, and in vivo cytotoxic concentration ranges > 100 μg/mL. The protein expression levels and mRNA transcription levels of TYR, TRP-1, and MITF were decreased in a dose-dependent manner by the treatment with PN3. PN3 interfered with the phosphorylation of intracellular protein kinase A (PKA)/cAMP response element-binding protein (CREB), demonstrating potent anti-melanogenic effects. PN3 could inhibit PKA/CREB and the subsequent degradation of microphthalmia-associated transcription factor (MITF), resulting in the suppression of melanogenic enzymes and melanin production, probably because of the presence of flavonoid compounds. These properties make it a candidate as an additive to whitening cosmetics.

Determination of antioxidant activity of Hibiscus sabdariffa and Croton caudatus in Saccharomyces cerevisiae model system

From ancient times, plants and plant derived products are exploited as a prominent source of folkloric medicines with tremendous therapeutic potential for an array of health disorders. In the present study, ethanolic leaf extract of Hibiscus sabdariffa and Croton caudatus were evaluated for free radical scavenging activity in Saccharomyces cerevisiae model system. H. sabdariffa and C. caudatus showed tremendous DPPH free radical scavenging potential with an IC50 value of 184.88 and 305.39 µg/mL respectively at a concentration of 500 µg/mL. The ethanolic leaf extract of H. sabdariffa and C. caudatus also showed significant hydoxyl radical scavenging and total antioxidant activity. Ascorbic acid was used as positive control. The in vitro antioxidant activity was further supported by in vivo studies using radical scavenging mechanism in S. cerevisiae wild type and its isogenic deletion strains sod1∆ and tsa1∆. The mutant yeast cells substantially scavenged the stress generated by H2O2 when supplemented with ethanolic leaf extract of H. sabdariffa and C. caudatus as evident from spot assays followed by fluorescence assay (DCF-DA) using fluorescence microscopic and intensity studies. H. sabdariffa and C.caudatus significantly neutralize the ROS level in yeast mutants with concomitant decrease in fluorescence intensity as compared to the untreated yeast cells. The results suggested the efficacy of H. sabdariffa and C. caudatus as potent antioxidants in yeast system and thus their futuristic applications in therapeutics.

The role of wild fruits and vegetables in delivering a balanced and healthy diet

Without a doubt, fruits and vegetables are important components of a balanced and healthy diet. However, their consumption is very low in the world, with the lowest figures being reported in sub-Saharan Africa. The low consumption of fruits and vegetables means unbalanced and unhealthy diets, which has been linked to various diseases and conditions associated with increased mortality rates in worst cases. Poverty is the major contributor to the low consumption of fruits and vegetables in the majority of cases. However, the world, including sub-Saharan Africa, is endowed with numerous wild fruit and vegetable species which can be exploited and incorporated into the diets and help solve some nutrition related concerns. Therefore, in this review, we explore literature on wild fruits and vegetables with a special emphasis on some of the poorest regions of the world and where the lowest consumption figures are reported; their nutritional compositions; the status of their consumption and their role in the diet with a view to uncover their possible role in delivering a healthy and balanced diet as well as helping lower food and nutrition insecurity. A total of 396 articles were downloaded and analysed but only 213 were considered for this review. The results of the search indicate that wild fruits and vegetables are nutritionally rich and high in phytochemicals, especially antioxidants and therefore can possibly play a significant and positive role in delivering a healthy and balanced diet. However, the major challenge is the acceptability, accessibility as well as a lack of interest in wild fruits and vegetables and sheer neglect. People need to be educated using various forms of media on the nutritional and health benefits of these wild food plants with a view to bring them from the forest to the plate. Researchers need to channel more efforts towards domesticating them for ease of access, among other reasons. Governments need to incentivise the subsistence or commercial production of wild fruits and vegetables in order to encourage farmers to cultivate them. However, seeds and/or seedlings need to be made available and affordable to the farmers. The 'hidden treasures' in the forests in the form of edible plants could easily play a positive and huge role in delivering a balanced and healthy diet, especially in poor parts of the world.

Hibiscus sabdariffa L. and Its Bioactive Constituents Exhibit Antiviral Activity against HSV-2 and Anti-enzymatic Properties against Urease by an ESI-MS Based Assay

For decades, Hibiscus sabdariffa L. and its phytochemicals have been shown to possess a wide range of pharmacologic properties. In this study, aqueous extract of Hibiscus sabdariffa (AEHS) and its bioactive constituent protocatechuic acid (PCA), have been evaluated in vitro for their antiviral activity against HSV-2 clinical isolates and anti-enzymatic activity against urease. Antiherpetic activity was evaluated by the titer reduction assay in infected Vero cells, and cytotoxicity was evaluated by the neutral red dye-uptake method. Anti-urease activity was determined by a developed Electrospray Ionization-Mass Spectrometry (ESI-MS)-based assay. PCA showed potent anti-HSV-2 activity compared with that of acyclovir, with EC₅₀ values of 0.92 and 1.43 µg∙mL⁻¹, respectively, and selectivity indices > 217 and > 140, respectively. For the first time, AEHS was shown to exert anti-urease inhibition activity, with an IC₅₀ value of 82.4 µg∙mL⁻¹. This, combined with its safety, could facilitate its use in practical applications as a natural urease inhibitor. Our results present Hibiscus sabdariffa L. and its bioactive compound PCA as potential therapeutic agents in the treatment of HSV-2 infection and the treatment of diseases caused by urease-producing bacteria.

Comparison of metabolic profiles and bioactivities of the leaves of three edible Congolese Hibiscus species

Methanolic and dichloromethane extracts from the leaves of Congolese Hibiscus species were characterised by chromatographic and spectroscopic techniques and their in vitro biochemical activities against ROS production were evaluated in cellular models and on an enzyme, myeloperoxidase (MPO), involved in inflammation. Hibiscus acetosella has a chemical fingerprint different from Hibiscus cannabinus and Hibiscus sabdariffa both having similar fingerprints. Major compounds were polyphenols, represented mainly by caffeoyl-hydroxycitric acid for H. acetosella and neochlorogenic acid for the two other species. All extracts displayed high cellular antioxidant activity with IC₅₀ values ranging from 0.5 to 3 μg mL^-1 using lucigenin on neutrophils. Dichloromethane extracts showed more efficient effects on extracellular ROS production and MPO activity. Antioxidant and anti-inflammatory activities of caffeoyl-hydroxycitric acid were significantly higher than those of neochlorogenic acid. The bioactivities of Hibiscus species were positively correlated with their phytochemical content and could justify their use as local nutraceutical resources and medicines.

In vitro synergistic effect of Hibiscus sabdariffa aqueous extract in combination with standard antibiotics against Helicobacter pylori clinical isolates

Context The increasing problem of drug-resistant strains has led to the failure of current treatment regimens of Helicobacter pylori (HP) infection. Recently, a new treatment strategy has been developed to overcome the problem by using natural products in combination with antibiotics to enhance the treatment efficacy. Objective The antimicrobial combinatory effect of the aqueous extract of Hibiscus sabdariffa L. (Malvaceae) (AEHS) with antibiotics (clarithromycin, CLA; amoxicillin, AMX; metronidazole, MTZ) has been evaluated in vitro against HP strains. Materials and methods Hibiscus calyces (35 g) were brewed in 250 mL of boiled water for 30 min, and minimum inhibitory concentrations (MICs) were determined by agar dilution method. The checkerboard assay was used to evaluate the antimicrobial combinatory effect according to the sum of fractional inhibitory concentration (∑FIC) indices. Results In this study, AEHS exerted remarkable bacteriostatic effect against all HP strains tested with MICs values ranging from 9.18 to 16.68 μg/mL. Synergy effect of AEHS with CLA or MTZ was obtained against four of seven HP strains tested with ∑FIC ranging from 0.21 to 0.39. The additive effect of AEHS with AMX was obtained against five of seven HP strains tested with ∑FIC ranging from 0.61 to 0.91. Conclusion This study presents AEHS as a potent therapeutic candidate alone, or in combination with antibiotics for the treatment of HP infection.

Review of anticancer mechanisms of isoquercitin

This review was based on a literature search of PubMed and Scielo databases using the keywords “quercetin, rutin, isoquercitrin, isoquercitin (IQ), quercetin-3-glucoside, bioavailability, flavonols and favonoids, and cancer” and combinations of all the words. We collected relevant scientific publications from 1990 to 2015 about the absorption, bioavailability, chemoprevention activity, and treatment effects as well as the underlying anticancer mechanisms of isoquercitin. Flavonoids are a group of polyphenolic compounds widely distributed throughout the plant kingdom. The subclass of flavonols receives special attention owing to their health benefits. The main components of this class are quercetin, rutin, and IQ, which is a flavonoid and although mostly found as a glycoside, is an aglycone (lacks a glycoside side chain). This compound presents similar therapeutic profiles to quercetin but with superior bioavailability, resulting in increased efficacy compared to the aglycone form. IQ has therapeutic applications owing to its wide range of pharmacological effects including antioxidant, antiproliferative, anti-inflammatory, anti-hypertensive, and anti-diabetic. The protective effects of IQ in cancer may be due to actions on lipid peroxidation. In addition, the antitumor effect of IQ and its underlying mechanism are related to interactions with Wnt signaling pathway, mixed-lineage protein kinase 3, mitogen-activated protein kinase, apoptotic pathways, as well proinflammatory protein signaling. This review contributed to clarifying the mechanisms of absorption, metabolism, and actions of IQ and isoquercitrin in cancer.

Comparative Study of Phenolic Profile, Antioxidant Capacity, and Color-composition Relation of Roselle Cultivars with Contrasting Pigmentation

Roselle is a plant that accumulates anthocyanins significantly, hence its importance as food coloring and as a source of antioxidant compounds for human health. This study was aimed to determine phenolic composition and antioxidant capacity of methanolic extracts, and beverages obtained from native roselle cultivars in Mexico (Negra, Sudan, Rosa and Blanca) with different degrees of pigmentation, and to establish the color-composition relationship. Chromatographic methods were used to determine phenolic compounds: flavanols, flavonols, benzoic, hibiscus and phenolic acids as well as two main anthocyanins (cyanidin 3-sambubioside and delphinidin 3-sambubioside). The antioxidant capacity was evaluated by ABTS and FRAP assays. Tristimulus colorimetry showed to be a useful technique to determine the color-composition relationship, leading to equations that allowed to predict anthocyanin content of roselle (R > 0.84). Also, a stepwise linear discriminant analysis (SLDA) was developed in order to classify roselle cultivars. The obtained mathematical model could be an important tool to be used in colorimetric characterization of functional compounds used in food processing.

Variations in chemical fingerprints and major flavonoid contents from the leaves of thirty-one accessions of Hibiscus sabdariffa L

The leaves of Hibiscus sabdariffa L. have been used as traditional folk medicines for treating high blood pressure and fever. There are many accessions of H. sabdariffa L. throughout the world. To assess the chemical variations of 31 different accessions of H. sabdariffa L., fingerprinting analysis and quantitation of major flavonoids were performed by high‐performance liquid chromatography (HPLC). The HPLC method was validated for linearity, sensitivity, precision, repeatability and accuracy. A quadrupole‐time‐of‐flight mass spectrometry (Q‐TOF‐MS) was applied for the characterization of major compounds. A total of 9 compounds were identified, including 6 flavonoids and 3 phenolic acids. In the fingerprint analysis, similarity analysis (SA) and principal component analysis (PCA) were used to differentiate the 31 accessions of H. sabdariffa L. Based on the results of PCA and SA, the samples No. 15 and 19 appeared much different from the main group. The total content of five flavonoids varied greatly among different accessions, ranging from 3.35 to 23.30 mg/g. Rutin was found to be the dominant compound and the content of rutin could contribute to chemical variations among different accessions. This study was helpful to understand the chemical variations between different accessions of H. sabdariffa L., which could be used for quality control. © 2015 The Authors Biomedical Chromatography Published by John Wiley & Sons Ltd.