The inhibitory effect of Cassia spectabilis methanol leaf extract was evaluated against biofilm forming Candida albicans, which was sensitive to 6.25 mg/ml concentration of the extract. Transmission (TEM) and scanning electron microscope (SEM) observations were used to study the anticandidal activity and prevention of biofilm formation by the C. spectabilis extract. SEM analysis further revealed reduction in C. albicans biofilm in response to the extract. The main abnormalities noted via TEM study was the alterations in morphology and complete collapse of the yeast cells after 36 h of exposure to the extract. The significant antifungal activity shown by this methanol extract of C. spectabilis suggests its potential against infections caused by C. albicans.
The fungicidal activity of Cassia spectabilis leaf extracts was investigated using the disk diffusion technique and the broth dilution method. The extract showed a favorable antimicrobial activity against Candida albicans with a minimum inhibition concentration(MIC) value of 6.25 mg / ml. Apart from the fungicidal effects, imaging using scanning electron microscopy (SEM) was done to determine the major alterations in the microstructure of the C. albicans. The main abnormalities noted in the SEM studies were the alterations in morphology and complete collapse of the yeast cells after 36 h of exposure to the extract. The in vitro time-kill study performed using the leaf extract at 1/2, 1 or 2 times of the MIC significantly inhibited the yeast growth with a noticeable drop in optical density (OD) of yeast culture, thus confirming the fungicidal effect of the extract on C. albicans. In addition, in vivo antifungal activity studies on candidiasis in mice showed a 5-fold decrease in Candida in kidneys and blood samples in the groups of animals treated with the extract (2.5 g / kg body weight). In an acute toxicity study using mice, the acute minimum fatal dose of the extract was greater than 2000 mg / kg, and we found no histopathological changes in macroscopic examination by necropsy of mice treated with extract. We conclude that the extract may be safely used as an anticandidal agent.
Consecutive chloroform, ethanol, and ethyl acetate partitions of extracts from winged bean [Psophocarpus tetragonolobus (L.) DC] root, stem, leaf, and pod extracts were tested for their antimicrobial activity against 19 microbial species, including 11 bacterial pathogens, four yeasts, and four molds using the disk diffusion assay technique. The pod extract was found to be most effective against all of the tested organisms, followed by the stem, root, and leaf extracts, and the ethanol fraction showed the most significant (p < 0.05) antimicrobial activity against all of the tests among three soluble fractions of extract, followed by the ethyl acetate and chloroform fractions. The minimum inhibitory concentrations (MICs) of extracts determined by the broth dilution method ranged from 1.25 to 10.0 mg/mL. The MIC of ethanol fraction of pod extracts was the lowest by comparison with the other two extracts. The MIC for fungi was at or below 2.5 mg/mL and for bacteria was at or above 2.5 mg/mL.
Some synthetic preservatives have become controversial because they have been proven to cause health problems. These increased health concerns have led consumers to prefer food preservatives based on natural products. Hence, Stenochlaena palustris leaf extract was used in this study to evaluate the antifungal activity against food borne pathogen, Aspergillus niger. The value of minimum inhibitory concentration and minimum fungicidal concentration of leaf extract for this fungus grown on Potato Dextrose Agar medium was 50 mg/ml. IC50 value for the hyphal growth of A. niger was at a concentration of 17.41 mg/ml. Morphology changes of A. niger treated with the fern leaf extract was observed through scanning electron microscope. The thread-like and elongated hyphae cell wall was disrupted, with some appearing flattened and others being broken. Currently, there is growing interest in using natural food preservatives such as medicinal plant extracts for preserving foods to reduce outbreaks of foodborne pathogenic microorganisms. Hence, S. palustris appears to have promise as a safe alternative natural product-based food preservative for future generations.
To determine the major changes in the microstructure of Candida albicans (C. albicans) after treatment with Euphorbia hirta (E. hirta) L. leaf extract.
The extract of the Psophocarpus tetragonolobus pods has been tested for antimicrobial activity in a disk diffusion assay on eight human pathogenic bacteria and two human pathogenic yeasts. The extracts of P. tetragonolobus possessed antimicrobial activity against all tested strains. The ethanolic extract of P. tetragonolobus pods was further tested for in vivo brine shrimp lethality test and in vitro sheep erythrocyte cytotoxic assay. The brine shrimp lethality test exhibited no significant toxicity (LC(50)=1.88 mg/ml) against Artemia salina, whereas sheep erythrocyte test showed significant toxicity. The reason for haemolysis of erythrocyte was discussed. The P. tetragonolobus extract with high LC(50) value signified that this plant is not toxic to human. This result also suggested that the ethanolic extract of P. tetragonolobus pods is potential source for novel antimicrobial compounds.
The antimicrobial activities of the methanolic extracts of Euphorbia hirta L leaves, flowers, stems and roots were evaluated against some medically important bacteria and yeast using the agar disc diffusion method. Four Gram positive (Staphylococcus aureus, Micrococcus sp., Bacillus subtilis and Bacillus thuringensis), four Gram negative (Escherichia coli, Klebsiella pneumonia, Salmonella typhi and P. mirabilis) and one yeast (Candida albicans) species were screened. Inhibition zones ranged between 16-29 mm. Leaves extract inhibited the growth of all tested microorganisms with large zones of inhibition, followed by that of flowers, which also inhibited all the bacteria except C. albicans. The most susceptible microbes to all extracts were S. aureus and Micrococcus sp. Root extract displayed larger inhibition zones against Gram positive bacteria than Gram negative bacteria and had larger inhibition zones compared to stem extract. The lowest MIC values were obtained with E. coli and C. albicans (3.12 mg/mL), followed by S. aureus (12.50 mg/mL) and P. mirabilis (50.00 mg/mL). All the other bacteria had MIC values of 100.00 mg/mL. Scanning Electron Microscopic (SEM) studies revealed that the cells exposed to leaf extract displayed a rough surface with multiple blends and invaginations which increased with increasing time of treatment, and cells exposed to leaf extract for 36 h showed the most damage, with abundant surface cracks which may be related to final cell collapse and loss of function. Time-kill assay of C. albicans indicated a primarily fungicidal effect at 1- and 2-fold MIC. E. hirta extracts had LC(50) values of 0.71, 0.66, 0.41 and 0.03 mg/mL for stems, leaves, roots and flowers, respectively against Artemia salina. Hence, these plants can be used to discover new bioactive natural products that may serve as leads in the development of new pharmaceuticals.
Although there is increasing concern about the toxicity of nanoplastics, the effects of nanoplastic exposure and subsequent recovery on immune responses, as well as antioxidant responses and gut microbiota, in crustaceans are rarely reported. In this study, the nonspecific immunity and antioxidant defense of Eriocheir sinensis were evaluated after acute exposure to various concentrations (0, 2.5, 5, 10 and 20 mg/L) of 75-nm polystyrene nanoplastics (PS-NPs) for 48 h, as well as after 7 days of recovery from the nanoplastic environment. The results showed that, after 48 h of exposure, nanoplastics were observed in the gills, hepatopancreas and gut. However, no nanoplastics were found in the gut after 7 days of recovery. Under nanoplastic-induced stress, Hc, Relish, proPO, and LITAF mRNA levels increased in the gills and hepatopancreas for 48 h. Expression of the myd88, Hc, Relish and proPO genes decreased in the gills during the 7-day recovery period. Exposure to nanoplastics for 48 h and recovery for 7 days significantly decreased the activities of lysozyme (LZM) alkaline phosphatase (AKP), total superoxide dismutase (SOD) and phenoloxidase (POD) and, glutathione peroxidase (GPX) in the hepatopancreas. Meanwhile, the relative abundance of pathogens exposed to 10 mg/L nanoplastics for 48 h increased at the species level, and these pathogens decreased significantly in the 7-day recovery period. These results suggested that exposure to nanoplastics for 48 h affected the activities of immune system enzymes and expression of immune-related genes in Eriocheir sinensis and altered the diversity and composition of their gut microbiota. E. sinensis could not recover from damage to the hepatopancreas within a 7-day recovery period. The results of this study provided insight into the effects of nanoplastics on crustaceans and it filled a gap in research on crustacean recovery after exposure to nanoplastics.