Antifungal efficacy of Thevetia peruviana leaf extract against Alternaria solani and characterization of novel inhibitory compounds by Gas Chromatography-Mass Spectrometry analysis

Phytochemical characterization of Thevetia peruviana (lucky nut) bark extracts by GC-MS analysis, along with evaluation of its biological activities, and molecular docking study

Thevetia peruviana (T. peruviana; Family: Apocynaceae), commonly known as Lucky Nut, is a traditionally and medicinally important plant, and the barks of the plant are traditionally used as anti-inflammatory, anti-diabetic, and antibacterial remedies. Thus, this study aimed to evaluate bioactive phytochemicals and in-vitro biological activities from the bark of T. peruviana using methanolic (TPM) and dichloromethane (TPD) extracts. The GC-MS analysis showed the presence of 54 and 39 bioactive compounds in TPM and TPD, respectively. The TPM extract has a higher level of total polyphenolic contents (TPC: 70.89 ± 1.08 and 51.07 ± 0.78 mg GAE/g extracts, while TFC: 56.89 ± 1.16 and 44.12 ± 1.76 Qu.E/g extracts for TPM and TPD, respectively). Herein, the results of antioxidant activities were also found in correlation with the total polyphenolic contents i.e., depicting the higher antioxidant potential of TPM compared to TPD. The significant inhibitory activities of extracts were observed against tyrosinase (TPM; 59.43 ± 2.87 %, TPD; 53.43 ± 2.65 %), lipoxygenase (TPM; 77.1 ± 1.2 %, TPD; 59.3 ± 0.1 %), and α-glucosidase (TPM; 71.32 ± 2.44 %, TPD; 67.86 ± 3.011 %). Furthermore, in comparison to co-amoxiclave, the antibacterial property against five bacterial strains was significant assayed. The compounds obtained through GC-MS analysis were subjected to in-silico molecular docking studies, and the phyto-constituents with maximum binding scores were then subjected to ADME analysis. The results of in-silico studies revealed that the binding affinity of several phyto-constituents was even greater than that of the standard inhibitory ligands. ADME analysis showed bioavailability radars of phyto-constituents having maximum docking scores in molecular docking. The results of this study indicated that T. peruviana has bioactive phytochemicals and therapeutic potential and may provide a basis for treating metabolic disorders (inflammatory diseases like rheumatism and diabetes), bacterial infections, and skin-related problems.

Antifungal In Vitro Activity of Phoradendron sp. Extracts on Fungal Isolates from Tomato Crop

Synthetic chemicals are mainly used for the control of fungal diseases in tomato, causing the phytopathogens to generate resistance to the chemical active ingredient, with a consequent risk to human health and the environment. The use of plant extracts is an option for the control of these diseases, which is why the main objective of this research was to study an alternative biocontrol strategy for the management of plant diseases caused by fungi through obtaining polyphenol extracts from mistletoe plants growing on three different tree species-mesquite (Prosopis glandulosa), cedar (Cedrus), and oak (Quercus), which contain flavones, anthocyanins, and luteolin. The overall chemical structure of the obtained plant extracts was investigated by RP-HPLC-ESI-MS liquid chromatography. The antifungal effect of these extracts was examined. The target phytopathogenic fungi were isolated from tomato plantations located in Altamira, Tamaulipas, Mexico. The microorganisms were characterized by classical and molecular methods and identified as Alternaria alternata, Fusarium oxysporum, Fusarium sp., and Rhizoctonia solani.

Comparative Transcriptome Analysis Unravels the Response Mechanisms of Fusarium oxysporum f.sp. cubense to a Biocontrol Agent, Pseudomonas aeruginosa Gxun-2

Banana Fusarium wilt, which is caused by Fusarium oxysporum f.sp. cubense Tropical Race 4 (FOC TR4), is one of the most serious fungal diseases in the banana-producing regions in east Asia. Pseudomonas aeruginosa Gxun-2 could significantly inhibit the growth of FOC TR4. Strain Gxun-2 strongly inhibited the mycelial growth of FOC TR4 on dual culture plates and caused hyphal wrinkles, ruptures, and deformities on in vitro cultures. Banana seedlings under pot experiment treatment with Gxun-2 in a greenhouse resulted in an 84.21% reduction in the disease. Comparative transcriptome analysis was applied to reveal the response and resistance of FOC TR4 to Gxun-2 stress. The RNA-seq analysis of FOC TR4 during dual-culture with P. aeruginosa Gxun-2 revealed 3075 differentially expressed genes (DEGs) compared with the control. Among the genes, 1158 genes were up-regulated, and 1917 genes were down-regulated. Further analysis of gene function and the pathway of DEGs revealed that genes related to the cell membrane, cell wall formation, peroxidase, ABC transporter, and autophagy were up-regulated, while down-regulated DEGs were enriched in the sphingolipid metabolism and chitinase. These results indicated that FOC TR4 upregulates a large number of genes in order to maintain cell functions. The results of qRT-PCR conducted on a subset of 13 genes were consistent with the results of RNA-seq data. Thus, this study serves as a valuable resource regarding the mechanisms of fungal pathogen resistance to biocontrol agents.

Impact of physical factors on bio-control potential of Lawsonia inermis leaf extract and bio-formulations as fungicides

The present study is carried out to ascertain the effect of different physical factors (sunlight, temperature, pH) and storage conditions on the antimicrobial efficacy of Lawsonia inermis leaf extracts and bio-formulation against the Alternaria alternata. In addition, the phytotoxic potential of 100% alcoholic crude extract as well as the acetone fraction of young leaves of Lawsonia inermis was also checked on seed germination of chilli (Capsicum annuum). Results showed that there was no adverse effect of wet heat (50–100 °C) and dry heat (40–90 °C) on extract and bio-formulation efficacy. Storage for 6 and 12 months had no adverse effect on extract and bio-formulation efficacy and the antifungal activity was observed similar to freshly prepared extract. We have used concentrations of 5,10, 15, 20 and 25 mg/ml to perform a phytotoxicity assay. The measurement of phytotoxicity was done by using the Standard blotter method and the result revealed that 5, 10 and 15 mg/ml concentration of the extract was non phytotoxic and were further used for in vivo experiments. These plant extracts and bio-formulations have extensive antimicrobial potential to be explored for application in sustainable agriculture.

Present scenarios and future prospects of herbal nanomedicine for antifungal therapy

The current COVID-19 epidemic is a sobering reminder that human susceptibility to infectious diseases remains even in our modern civilization. After all, infectious diseases are still the major reason of death globally. Healthcare authorities have often underestimated and ignored the threat posed by "microbial dangers," although they put millions of lives at risk every year. Overlooked developing diseases including fungal infections (FIs) contribute to roughly 1.7 million fatalities per year. As many as 150 million cases of severe and potentially life-threatening FIs are reported each year. In the last few years, the number of instances has steadily increased. Most of them are invasive fungal infections that require specialized treatment and hospital care. In recent years herbal antifungal compounds have been explored to acquire effective and safe therapy against fungal infections. However, potential therapeutic effects are hampered by the poor solubility, stability, and bioavailability of these important chemicals as well as the gastric degradation that occurs in the gastrointestinal tract. To get around this issue, researchers have turned to novel drug delivery systems such as nanoemulsions, ethosomes, metallic nanoparticles, liposomes, lipid nanoparticles, transferosomes, etc by improving their limits, nanocarriers can enhance the medicinal effects of herbal oils and extracts. The present review article focuses on the available antifungal agents and their characteristics, mechanism of antifungal drugs resistance, herbal oils and extract as antifungal agents, challenges in the delivery of herbal drugs, and application of nano-drug delivery systems for effective delivery of antifungal herbal compounds.