Effect of henna and roselle extracts on pathogenic bacteria

ObjectiveTo investigate the antibacterial effects of water and ethanolic extracts of henna leaves and roselle calyxes against pathogenic bacteria isolated from domestic wastewater.MethodsThe antimicrobial activity was determined in the extracts using agar disc diffusion method. The antibacterial activities of extracts (2.5%, 5.0% and 10.0% w/v) of both henna and roselle were tested against one Gram-positive Bacillius subtilis; two Gram-negative Escherichia coli, Pseudomonas aeruginosa human pathogenic bacteria.ResultsEthanolic extracts had more antimicrobial activity than water extracts. Ethanolic extract of roselle had the highest antibacterial activity against all tested organisms, followed with ethanolic extract of henna. Pseudomonas aeruginosa was the most sensitive bacteria to plant extracts.ConclusionThe results of this study suggested that roselle contains more phyto-chemicals with antimicrobial activity than henna on the bacteria strains under study, and these phyto-chemicals were more effective when extracted by ethanol rather than water.     

The protective effect of aqueous extracts of roselle (Hibiscus sabdariffa L. UKMR-2) against red blood cell membrane oxidative stress in rats with streptozotocin-induced diabetes

OBJECTIVES:

The aim of this study was to investigate the protective effects of aqueous extracts of roselle (Hibiscus sabdariffa L. UKMR-2) against red blood cell (RBC) membrane oxidative stress in rats with streptozotocin-induced diabetes.

METHODS:

Forty male Sprague-Dawley rats weighing 230-250 g were randomly divided into four groups (n = 10 rats each): control group (N), roselle-treated control group, diabetic group, and roselle-treated diabetic group. Roselle was administered by force-feeding with aqueous extracts of roselle (100 mg/kg body weight) for 28 days.

RESULTS:

The results demonstrated that the malondialdehyde levels of the red blood cell membranes in the diabetic group were significantly higher than the levels in the roselle-treated control and roselle-treated diabetic groups. The protein carbonyl level was significantly higher in the roselle-treated diabetic group than in the roselle-treated control group but lower than that in the diabetic group. A significant increase in the red blood cell membrane superoxide dismutase enzyme was found in roselle-treated diabetic rats compared with roselle-treated control rats and diabetic rats. The total protein level of the red blood cell membrane, osmotic fragility, and red blood cell morphology were maintained.

CONCLUSION:

The present study demonstrates that aqueous extracts of roselle possess a protective effect against red blood cell membrane oxidative stress in rats with streptozotocin-induced diabetes. These data suggest that roselle can be used as a natural antioxidative supplement in the prevention of oxidative damage in diabetic patients.     

Effects of Hibiscus sabdariffa L. on serum lipids: A systematic review and meta-analysis

Ethnopharmacological relevance

Prevention of cardiovascular disease by modifying its major risk factors, including serum cholesterol levels, is an important strategy. Hibiscus sabdariffa L. has been promoted for reducing cholesterol levels, but its reported impact on cholesterol levels has been inconsistent. The study aimed to assess systematically the evidence and quality of current research on the effect of Hibiscus sabdariffa L. on blood lipids and its adverse effects.

Materials and methods

Electronic databases were searched up to June 2013 for relevant randomised controlled trials (RCTs). Journals and conference proceedings were also searched. The quality of the selected trials was assessed using the Cochrane Risk of Bias Assessment Tool. The efficacy results of similar studies were pooled if they used the same comparator. Outcomes examined were levels of total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol and triglycerides.

Results

Six studies involving 474 subjects met our inclusion criteria. These studies varied in terms of the types of interventions, comparators used, and duration of trials. Overall, Hibiscus sabdariffa L. did not produce any significant effect on any of the outcomes examined, when compared with placebo, black tea or diet. With short-term use it is well tolerated.

Conclusions

The available evidence from RCTs does not support the efficacy of Hibiscus sabdariffa L. in lowering serum lipids. Further rigorously designed trials with larger sample sizes are warranted to confirm the effects of HS on serum lipids.     

Uricosuric effect of Roselle (Hibiscus sabdariffa) in normal and renal-stone former subjects

AIM OF THE STUDY: The Roselle (Hibiscus sabdariffa) was investigated for its uricosuric effect. MATERIALS AND METHODS: A human model with nine subjects with no history of renal stones (non-renal stone, NS) and nine with a history of renal stones (RS) was used in this study. A cup of tea made from 1.5 g of dry Roselle calyces was provided to subjects twice daily (morning and evening) for 15 days. A clotted blood and two consecutive 24-h urine samples were collected from each subject three times: (1) at baseline (control); (2) on days 14 and 15 during the tea drinking period; and (3) 15 days after the tea drinking was stopped (washout). Serum and 24-h urinary samples were analyzed for uric acid and other chemical compositions related to urinary stone risk factors. RESULTS: All analyzed serum parameters were within normal ranges and similar; between the two groups of subjects and among the three periods. Vis-à-vis the urinary parameters, most of the baseline values for both groups were similar. After taking the tea, the trend was an increase in oxalate and citrate in both groups and uric acid excretion and clearance in the NS group. In the RS group, both uric acid excretion and clearance were significantly increased (p<0.01). When the fractional excretion of uric acid (FEUa) was calculated, the values were clearly increased in both the NS and SF groups after the intake of tea and returned to baseline values in the washout period. These changes were more clearly observed when the data for each subject was presented individually. CONCLUSIONS: Our data demonstrate a uricosuric effect of Roselle calyces. Since the various chemical constituents in Roselle calyces have been identified, the one(s) exerting this uricosuric effect need to be identified.     

Evaluation of the potential of Trichoderma viride in the control of fungal pathogens of Roselle (Hibiscus sabdariffa L.) in vitro

The potential of Trichoderma viride as a bio-control agent was evaluated in vitro against Roselle pathogens i.e. Phoma exigua, Fusarium nygamai and Rhizoctonia solani [1] using the dual culture technique. Volatile and non-volatile inhibitors of Trichoderma were also evaluated for this purpose. T. viride [2] was shown to have a marked inhibitory effect on the tested pathogens in vitro. Maximum inhibition occurred against P. exigua, with 71.76% reduction in mycelial radial growth. The three pathogens, P. exigua, F. nygamai and R. solani were also found to be susceptible to the volatile inhibitors produced by T. viride, giving rise to growth inhibition of about 68% in each case. When T. viride non-volatile metabolites were tested against the pathogens, maximum inhibition occurred against R. solani (73.95% mycelial growth inhibition), followed by P. exigua (37.17% inhibition). The inhibitory effect of the non-volatile metabolites on F. nygamai was, however, minimal.     

Morphological characteristics and pathogenicity of fungi associated with Roselle (Hibiscus Sabdariffa) diseases in Penang, Malaysia

Roselle, or Jamaica sorrel (Hibiscus sabdariffa) is a popular vegetable in many tropical regions, cultivated for its leaves, seeds, stems and calyces which, the dried calyces are used to prepare tea, syrup, jams and jellies and as beverages. The main objectives of this study were to identify and characterise fungal pathogens associated with Roselle diseases based on their morphological and cultural characteristics and to determine the pathogenicity of four fungi infecting Roselle seedlings, namely Phoma exigua, Fusarium nygamai, Fusarium tgcq and Rhizoctonia solani in Penang. A total of 200 fungal isolates were obtained from 90 samples of symptomatic Roselle tissues. The isolates were identified based on cultural and morphological characteristics, as well as their pathogenicity. The fungal pathogen most frequently isolated was P. exigua (present in 45% of the samples), followed by F. nygamai (25%), Rhizoctonia solani (19%) and F. camptoceras (11%). Pathogenicity tests showed that P. exigua, F. nygamai, F. camptoceras and R. solani were able to infect both wounded and unwounded seedlings with different degrees of severity as indicated by the Disease severity (DS). R. solani was the most pathogenic fungus affecting both wounded and unwounded Roselle seedlings, followed by P. exigua that was highly pathogenic on wounded seedlings. F. nygamai was less pathogenic while the least pathogenic fungus was F. camptoceras, infecting only the unwounded seedlings but, surprisingly, not the wounded plants.     

Anti-fungal activity of cold and hot water extracts of spices against fungal pathogens of Roselle (Hibiscus sabdariffa) in vitro

Crude extracts of seven spices, viz. cardamom, chilli, coriander, onion, garlic, ginger, and galangale were made using cold water and hot water extraction and they were tested for their anti-fungal effects against the three Roselle pathogens i.e. Phoma exigua, Fusarium nygamai and Rhizoctonia solani using the ‘poisoned food technique’. All seven spices studied showed significant anti-fungal activity at three concentrations (10, 20 and 30% of the crude extract) in-vitro. The cold water extract of garlic exhibited good anti-fungal activity against all three tested fungi. In the case of the hot water extracts, garlic and ginger showed the best anti-fungal activity. Of the two extraction methods, cold water extraction was generally more effective than hot water extraction in controlling the pathogens. Against P. exigua, the 10% cold water extracts of galangale, ginger, coriander and cardamom achieved total (100%) inhibition of pathogen mycelial growth. Total inhibition of F. nygamai mycelial growth was similarly achieved with the 10% cold water extracts garlic. Against R. solani, the 10% cold water extract of galangale was effective in imposing 100% inhibition. Accordingly, the 10% galangale extract effectively controlled both P. exigua and R. solani in vitro. None of the hot water extracts of the spices succeeded in achieving 100% inhibition of the pathogen mycelial growth.