Antimicrobial activity, phytochemical analysis and toxicity test of Cosmos caudatus Kunth extract

The uses of natural products in the elimination of microorganism contaminations in food have increased nowadays. In this study, air-dried leaf methanolic extract of Cosmos caudatus Kunth was used. The antimicrobial activity of C. caudatus extract and time-kill curve analysis was evaluated against foodborne pathogens. The stability of extract at different pH and temperature also were evaluated. The identification and quantification of bioactive compounds were conducted using LC-MS/MS and HPLC. Three representative microorganisms were observed under transmission electron microscope (TEM). The effect of C. caudatus extract on natural microflora in selected food materials and its sensory acceptability were tested at different concentrations of extract for different exposure time. The toxicity level of extract was assessed using Artemia salina spp. Results showed that all tested foodborne pathogens were susceptible to C. caudatus extract at different range of MIC value from 6.25 to 50.00 mg/ml. Time-kill curve study shows that all tested foodborne pathogens can be killed by the extract with different time-killing curve. Generally, the antimicrobial activities of C. caudatus extract were not significantly affected on tested pH and temperatures. LC-MS/MS analysis identified the presence of rutin, quercetin 3-O-glucoside, quercetin 3-O-arabinoside, quercetin 3-O-rhamnoside and quercetin. HPLC analysis showed the highest concentration was quercetin rhamnoside (29.66 mg/g). All the identified active compounds proved possess antimicrobial activities. TEM observation showed changing on the pathogen cells’s structure. Generally the significant reduction of natural microflora in raw food materials were started at 0.05% of C. caudatus extract for 10 min of exposure time, and the sensory acceptability at this concentration and time were accepted by the panellists. The toxicity study demonstrated that C. caudatus extract was not toxic to A. salina (LC50 = 3.54 mg/ml). In conclusion, C. caudatus extract exhibits antimicrobial activities, thus can be developed as natural sanitizer for washing raw food materials

Melaleuca cajuputi leaf extract accelerates wound healing in African catfish, Clarias gariepinus

African catfish Clarias gariepinus is a scale-less fish prone to injury from high stocking under captive condition. Untreated wounds are susceptible to pathogenic infections that can cause biological and economic losses. This study evaluated the potential of Melaleuca cajuputi leaf extract (MCLE) for wound treatment in artificially injured C. gariepinus. Methanol extracts of M. cajuputi were freeze-dried and applied as treatment solutions as follows; 0.0 mg/L, 12.7 mg/L, 25.4 mg/L, and 38.1 mg/L. Tetracycline was used as a positive control group. The fish were artificially injured (i.e., laceration of 1 cm long, 0.4 cm depth) on both lateral sides and allowed to swim in the treatment solutions for 30 days. Wound healing progress, histological changes, hematological and biochemical parameters are herein reported. Results revealed that MCLE treatments caused faster epidermal cell migration, epidermal covering, and cell proliferation as early as 1 h after the artificial injury was inflicted compared to the control. At 3 h, the MCLE treatment at 12.7 and 25.4 mg/L caused the wounds to be closed and initiated the formation of the basement membrane; where these conditions were found only after 6 h with the tetracycline and control treatments. Meanwhile, the vascularization was found to occur after about 6 h in the 12.7 and 25.4 mg/L MCLE treated fish, whereas the process was delayed until 12 h in untreated fish. Our finding shows that treatment of fish wounds for 30 days with MCLE did not affect the health status of the fish as no significant changes (p > 0.05) were observed between the MCLE-treated and control groups for most parameters. It was concluded that the treatment of injured C. gariepinus can be done using MCLE concentration between 12.7 and 25.4 mg/L to accelerate healing

Screening of selected Malaysian herbs as the potential broad spectrum antimicrobial agent against bacterial diseases of fish

The control of fish disease is mostly based on synthetic antimicrobial agents. Indiscriminate usage of antimicrobial agents has resulted in antibiotics resistance. Therefore, the present study aims to evaluate the potential antimicrobial properties of herbal plants as an alternative antimicrobial agent. The susceptibility of fish pathogens namely Bacillus sp., Enterococcus faecalis, Staphylococcus aureus, Streptococcus agalactiae, Aeromonas hydrophila, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Vibrio alginolyticus towards aqueous and methanolic extracts of Cosmos caudatus, Curcuma mangga, Justicia gendarussa, Piper betle and Zingiber zerumbet were assessed using the agar well diffusion, Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays. The methanolic extracts were found active against all tested bacteria, compared to aqueous extracts. The best antibacterial activity was demonstrated by methanolic extract of P. betle, followed by Z. zerumbet, C. caudatus, C. mangga and J. gendarussa, with the lowest MIC and MBC values of 0.39 and 1.56 mg/mL, respectively. The methanolic extracts of P. betle and Z. zerumbet also had greater inhibitory effects than some of the commercial antibiotics, particularly tetracycline and erythromycin. Overall findings suggested that the methanolic extracts of P. betle and Z. zerumbet are potential to be developed as new antimicrobial agents to prevent fish bacterial diseases

In vitro antimycotic activity of chemical constituents from Dipterocarpus verrucosus, Dipterocarpus cornutus and Diptericarpus crinitus against opportunistic filamentour fungi

This paper will discuss, in vitro investigation of chemical constituents extracted from the stem bark of Dipterocarpus verrucosus, Dipterocarpus crinitus and Dipterocarpus cornutus against opportunistic filamentous fungi. In this research, 17 compounds comprised of twelve oligostilbenoids, (-)--viniferin ,(-)-laevifonol, (-)-hopeaphenol , (-)-isohopeaphenol, vaticanol B, diptoindonesin E, hemsleyanol D, davidiol A, resveratrol, ampelopsin A, ampelopsin F, together with three other phenolic; gallic acid derivative, (-)-bergenin, scopoletin and 4-methoxygallocathecin and also two terpene; β-sitosterol and β-sitosterol glucoside have been isolated. In this study, the crude extracts and isolated compounds were evaluated regarding to their antifungal activity; in terms of MIC, MFC and germination assay against pathogenic fungi strains, namely Aspergillus flavus (AF), Aspergillus oligosporus (AO), Rhizophus oryzae (RO) and Fusarium oxysporum (FO) using Clinical and Laboratory Standard Institute (CLSI) methods. The MIC of crude extracts and isolated compounds against all fungi ranged from 3.8 - 500 μg/mL. F. oxysporum shows the most sensitive microorganisms on crude extract: D. verrucosus, D. cornutus and isolated compound: ε-viniferin with MIC of 3.8 μg/mL. The MIC was lower compared to amphotericin B (4 μg/ml). The strain was killed at the MFC of 31.3, 31.3 and 15.6 μg/mL respectively, as compared to amphotericin B (8 μg/mL). Compounds: resveratrol, laevifonol, ε-viniferin, ampelopsin F, vaticanol B, vaticanol A, isomer of hopeaphenol and isohopeaphenol, β-sitosterol and β-sitosterolglucoside possessed an inhibitory activity on the conidial germination of F. oxysporum at the concentration of 4× MIC. On top of that, D. cornutus, ampelopsin A and hemsleyanol D possessed a complete sterility at the concentration of 2×MIC while D.verrucosus achieved its inhibitory activity at 1× MIC. To the best of our study, there is no data discussing the inhibition of conidial germination of filamentous fungi using the tested compounds and crudes tested