Antifungal Activity of Saponins from the Fruit Pericarp of Sapindus mukorossi against Venturia inaequalis and Botrytis cinerea

GCMS characterization and biological potential of the seeds and aerial part of Galium tricorne Stokes

Abstract Natural products have long been proven very effective against various challenging diseases including cancer and bacterial infections. Galium tricorne is one of the important source of natural products, which has not been explored till date in spite of its profound ethnomedicinal prominence. The current study has been designed to explore the biological potential of G. tricorne and to extract and isolate chemical constituents from its aerial part and seeds respectively along with identification of their chemical constituents. Phytochemical screening was performed to figure out the presence of secondary metabolite in G. tricorne. Crude Methanolic extract (Gt.Crd), which was obtained from the aerial part while the fatty acids were extracted from the seeds, which were later on analyzed by GCMS. Similarly, Well Diffusion and MTT method were used for antibacterial activity and cancer cell line assay respectively. To evaluate the cytotoxic potential, brine shrimps were used. Likewise, in Gas Chromatography-Mass Spectroscopy (GC-MS) analysis a total number of 23 compounds were identified in Gt.Crd extract out of which 7 compounds were sorted out to have some sort of toxicity profile. In the same fashion, 5 fatty acids were identified in the seeds of G. tricorne. Moreover, among the fractions, chloroform fraction (Gt.Chf) exhibited greater zone of inhibition (ZOI) 20.37 mm followed by Gt.Crd 18.40 mm against S. aureus and S. pyogenes respectively. In cytotoxicity Gt.Chf was more active followed by ethyl acetate fraction (Gt.Eta) by exhibiting 88.32±0.62% (LC50=60 µg/mL) and 73.95±2.25% (LC50=80 µg/mL) respectively at 1000 µg/mL concentration of the tested sample. Gt.Chf exhibited greater cell line inhibitory activity (IC50=61 µg/mL) against HeLa cell line. Similarly, Gt.Crd displayed IC50 values of 167.84 µg/mL and 175.46 µg/mL against HeLa and NIH/3T3 cell line respectively. Based on the literature review and screenings, it may be concluded that the aerial part and seeds of G. tricorne are the rich sources of bioactive compounds. The results of the current study also authenticate the scientific background for the ethnomedicinal uses of G. tricorne.

Molluscicidal Activity of Compounds From the Roots of Aralia armata Against the Golden Apple Snail (Pomacea canaliculata)

Background: Aralia armata (Araliaceae) is considered to exhibit effective molluscicidal activity, however, the relationship between the chemical components and molluscicidal activity has not been clearly elucidated. This research attempts to decipher these correlations among the 15 compounds isolated from Vietnam-grown A. armata roots against the freshwater snail, Pomacea canaliculata, a gastropod causing severe damage in agricultural production. Methods: Fifteen saponins were isolated from the methanol root extract of A. armata using chromatographic methods and were identified using spectroscopic techniques. The compounds were screened for molluscicidal activity against P. canaliculata, as well as toxicity against brine shrimp ( Artemia sp.) and phytotoxicity against rice germination and growth. Results: The saponin compounds exhibited extraordinary inhibition of P. canaliculata with LC50 values ranging from 7.90 to 17.50 µg/mL. Notably, the active compounds from A. armata exhibit safety for both nontarget aquatic animals, specifically Artemia sp. with LC50 values between 148.55 and 193.22 µg/mL, and the growth and development of Oryza sativa L. plants showed very little difference compared with the negative control . A molecular docking analysis indicated P. canaliculata acetylcholinesterase (PcAChE) and the actin-binding protein villin (PcVillin) to be potential biomolecular targets of the A. armata saponins. Conclusion: The present experimental and in silico data illustrate the potential of A. armata in agricultural applications.

Potential inhibitory activity of phytoconstituents against black fungus: In silico ADMET, molecular docking and MD simulation studies

Mucormycosis or “black fungus” has been currently observed in India, as a secondary infection in COVID-19 infected patients in the post-COVID-stage. Fungus is an uncommon opportunistic infection that affects people who have a weak immune system. In this study, 158 antifungal phytochemicals were screened using molecular docking against glucoamylase enzyme of Rhizopus oryzae to identify potential inhibitors. The docking scores of the selected phytochemicals were compared with Isomaltotriose as a positive control. Most of the compounds showed lower binding energy values than Isomaltotriose (-6.4 kcal/mol). Computational studies also revealed the strongest binding affinity of the screened phytochemicals was Dioscin (-9.4 kcal/mol). Furthermore, the binding interactions of the top ten potential phytochemicals were elucidated and further analyzed. In-silico ADME and toxicity prediction were also evaluated using SwissADME and admetSAR online servers. Compounds Piscisoflavone C, 8-O-methylaverufin and Punicalagin exhibited positive results with the Lipinski filter and drug-likeness and showed mild to moderate of toxicity. Molecular dynamics (MD) simulation (at 300 K for 100 ns) was also employed to the docked ligand-target complex to explore the stability of ligand-target complex, improve docking results, and analyze the molecular mechanisms of protein-target interactions.

Triterpenoid Saponins from Washnut (Sapindus mukorossi Gaertn.)—A Source of Natural Surfactants and Other Active Components

Sapindus mukorossi Gaertn., also called the washnut, is a tropical tree of the Sapindaceae family. The plant owes its name to its cleaning and washing properties used by the local population as a natural detergent. The most important ingredients of the plant are triterpenoid saponins contained in many parts of the plant, inducing fruits, galls, or roots. The tree also contains other valuable, biologically active compounds that are obtained by extraction methods. Raw or purified extract and isolated saponins are valuable plant products that can be used in the food, pharmaceutical, cosmetic, and chemical industries. This review includes the most important biological and surfactant properties of extracts and isolated saponins obtained from various parts of the plant.

The heat shock protein 20 gene editing suppresses mycelial growth of Botryosphaeria dothidea and decreases its pathogenicity to postharvest apple fruits

Apple ring rot caused by Botryosphaeria dothidea is an essential and prevalent disease in the apple orchard in China. Our previous study demonstrated that dimethyl trisulfide (DT) from Chinese leek (Allium tuberosum) significantly suppressed the mycelial growth of B. dothidea and inhibited the incidence of apple ring rot postharvest. However, the mechanism underlying the inhibitory role of DT against B. dothidea is not fully understood. Comparing the control and the DT-treated B. dothidea mycelial transcriptomes revealed that heat shock protein 20 (Hsp20) strongly responded to DT treatment. This study identified four Hsp20 genes throughout the B. dothidea genome (BdHsp20_1-4). Each BdHsp20 gene had a conserved ACD with a variable N-terminal region and a short C-terminal extension. The segmental duplication event has contributed to the expansion of the BdHsp20 gene family. Compared to the wild-type strain, the CRISPR/Cas9 gene-edited BdHsp20 mutant (ΔBdHsp20) decreased the mycelial growth by 55.95% and reduced the disease symptom in postharvest apple fruit by 96.34%. However, the BdHsp20 complemented strain (ΔBdHsp20_C) significantly restored the growth and pathogenicity, which suggested that the BdHsp20 gene was closely involved in the growth and pathogenicity of B. dothidea. This study would accelerate the exploration of the molecular mechanism of the inhibitory effect of DT against B. dothidea and also provide new insights for the management of apple ring rot disease.

Anti-phytopathogen terpenoid glycosides from the root bark of Chytranthus macrobotrys and Radlkofera calodendron

Chytranthus macrobotrys and Radlkofera calodendron are two Sapindaceae characterized by a lack of phytochemical data. Both root barks from the two Sapindaceae species were processed by ethanol extraction followed by the isolation of their primary constituents by liquid chromatography. This process yielded four previously undescribed terpenoid glycosides together with eight known analogues. Extracts and isolated compounds from C. macrobotrys and R. calodendron were then screened for antimicrobial activity against fifteen phytopathogens. The biological screening also involved extracts and pure compounds from Blighia unijugata and Blighia welwitschii, two Sapindaceae previously studied by our group. Phytopathogens were chosen based on their economic impact on agriculture worldwide. The selection was composed primarily of fungal species including; Pyricularia oryzae, Gaeumannomyces graminis var. tritici, Zymoseptoria tritici, Fusarium oxysporum, Botrytis cinerea, Pythium spp., Trichoderma spp. and Rhizoctonia solani. Furthermore, pure terpenoid glycosides were tested for the first time against wood-inhabiting phytopathogens such as; Phaeomoniella chlamydospora, Phaeoacremonium minimum, Fomitiporia mediterranea, Eutype lata and Xylella fastidiosa. Raw extracts exhibited different levels of activity dependent on the organism. Some pure compounds, including 3-O-α-L-arabinopyranosyl-(1 → 4)-β-D-xylopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin, 3-O-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin (α-hederin), 3-O-β-D-glucopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin (macranthoside A) and 3-O-α-L-arabinopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosylhederagenin (clemontanoside C), exhibited significant growth inhibitions on Pyricularia oryzae, Gaeumannomyces graminis var. tritici, Fomitiporia mediterranea and Zymoseptoria tritici. Monodesmoside triterpene saponins, in particular, exhibited MIC (IC₁₀₀) values as low as 25 μg/ml and IC₅₀ values as low as 10 μg/ml against these phytopathogens. Structure-activity relationships, as well as plant-microbe interactions, were discussed.

Bamboo Tar as a Novel Fungicide: Its Chemical Components, Laboratory Evaluation, and Field Efficacy Against False Smut and Sheath Blight of Rice and Powdery Mildew and Fusarium Wilt of Cucumber

The application of agricultural and forest residues can benefit the environment and the economy; however, they also generate a large amount of byproducts. In this study, bamboo tar (BT), a waste product of bamboo charcoal production, was dissolved in natural ethanol and the surfactant alkyl glucoside to manufacture a 50% (wt/wt) BT emulsifiable concentrate (BTEC) biopesticide. BTEC was screened for fungicidal activity against pathogens. The greatest activity was seen against Ustilaginoidea virens with a half-maximal effective concentration (EC₅₀) value of 6 mg/liter. Four phytopathogenic fungi, Podosphaera xanthii, Rhizoctonia solani, Fusarium oxysporum, and Botrytis cinerea, showed EC₅₀ values of <60 mg/liter. Greenhouse tests in vivo showed 2,000 mg/liter BTEC had a 78.4% protective effect against U. virens, and replicated treatments had an 80.6% protective effect. In addition, replicated 2-year field trials were conducted in two geographic locations with four plant diseases: false smut (U. virens), rice sheath blight (Thanatephorus cucumeris [Frank] Donk), cucumber powdery mildew (P. xanthii), and cucumber Fusarium wilt (F. oxysporum). Results showed that 1,000 to 2,000 mg/liter BTEC significantly inhibited these diseases. Gas chromatography-mass spectrometry analysis showed that the total phenolic mass fractions of two BT samples were 45.39 and 48.26%. Eleven components were detected, and their percentage content was as follows (from high to low): 2,6-dimethoxyphenol > 2- or 4-ethylphenol > 2- or 4-methylphenol > phenol > 4-ethylguaiacol > dimethoxyphenol > 4-methylguaiacol > 4-propenyl-2,6-dimethoxyphenol > 2,4-dimethylphenol. Some of the phenolic compounds identified from the tar might be fungicidally active components. BT is a biochar waste, which has potential as a biofungicide and has promise in organic agriculture. The value of this tar may not be because of any fundamental physical differences from other synthetic fungicides but rather caused by reduced production expenses and more efficient use of waste products.

BotRisk: simulating the annual bunch rot risk on grapevines (Vitis vinifera L. cv. Riesling) based on meteorological data

The aim of the present investigations was to simulate the annual risk of bunch rot (Botrytis cinerea) on Vitis vinifera L. cv. Riesling grapes based on three long-term (n = 3 × 7 = 21 cases) assessment data sets originating from three Central European grape-growing regions. Periods when meteorological parameters were significantly (p < 0.01) correlated with the cumulative degree day (CDD_7;18;24) reaching 5% disease severity were determined by Window Pane analysis. Analyses revealed five critical weather constellations ("events") influencing annual epidemics: relatively low temperatures after bud break, dry conditions during flowering, high temperatures after flowering, and low temperatures and high precipitation sums during/after veraison were all associated with thermal-temporal early epidemics. Meteorological data in each of the five events served as input for the bunch rot risk model "BotRisk." The multiple linear regression model resulted in an adjusted coefficient of determination (R²_adj.) of 0.63. BotRisk enables (i) the simulation of the thermal-temporal position of the annual epidemic and, based on this, (ii) the classification of the annual bunch rot risk into three classes: low, medium, or high risk. According to leave-one-out cross-validation, 11 of 21 case studies were correctly classified. No systematic bias caused by location was observed, indicating that the transfer of the model into other locations with comparable climatic conditions could be possible. BotRisk (i) represents a novel viticultural decision support tool for crop cultural and chemical measures against bunch rot and (ii) enables an estimation of the bunch rot risk under changing environmental conditions.

Optimization of Microwave-Assisted Extraction Saponins from Sapindus mukorossi Pericarps and an Evaluation of Their Inhibitory Activity on Xanthine Oxidase

A microwave-assisted extraction (MAE) method was applied to separate saponins from Sapindus mukorossi pericarps. The most important factors of the six extraction parameters were selected using Plackett–Burman designs; therefore, the further extraction procedure was optimized using the Box–Behnken designs; meanwhile, the optimum processing parameters and well-pleasing saponins extraction rate were inferred. The final operation conditions were the ethanol concentration of 40%, soaking time of 3 h, particle size of 80–100 meshes, extraction time of 13 min, solvent-solid ratio of 19 mL/g, and microwave power of 425 W. Based on the optimal extraction parameters, the extraction rate of the saponins by means of MAE technique reached 280.55 ± 6.81 mg/g, which exceeds yields acquired using conventional manners. Saponins from S. mukorossi have obvious xanthine oxidase inhibitory properties in vitro compared with allopurinol. The saponins displayed a type of competitive inhibition of xanthine oxidase. In conclusion, a MAE technique in association with a response surface design provides an efficient extraction tactics, which could sufficiently isolate saponins from S. mukorossi pericarps; further, this technique could be applied to the dissociation of other bioactive substances from plant sources. In addition, the saponins may be a promising alternative to conventional medicine to treat gout and other inflammation-associated disorders to mitigate the side effects of traditional drugs.

Dual Mode of the Saponin Aescin in Plant Protection: Antifungal Agent and Plant Defense Elicitor

Being natural plant antimicrobials, saponins have potential for use as biopesticides. Nevertheless, their activity in plant-pathogen interaction is poorly understood. We performed a comparative study of saponins' antifungal activities on important crop pathogens based on their effective dose (EC₅₀) values. Among those saponins tested, aescin showed itself to be the strongest antifungal agent. The antifungal effect of aescin could be reversed by ergosterol, thus suggesting that aescin interferes with fungal sterols. We tested the effect of aescin on plant-pathogen interaction in two different pathosystems: Brassica napus versus (fungus) Leptosphaeria maculans and Arabidopsis thaliana versus (bacterium) Pseudomonas syringae pv tomato DC3000 (Pst DC3000). We analyzed resistance assays, defense gene transcription, phytohormonal production, and reactive oxygen species production. Aescin activated B. napus defense through induction of the salicylic acid pathway and oxidative burst. This defense response led finally to highly efficient plant protection against L. maculans that was comparable to the effect of fungicides. Aescin also inhibited colonization of A. thaliana by Pst DC3000, the effect being based on active elicitation of salicylic acid (SA)-dependent immune mechanisms and without any direct antibacterial effect detected. Therefore, this study brings the first report on the ability of saponins to trigger plant immune responses. Taken together, aescin in addition to its antifungal properties activates plant immunity in two different plant species and provides SA-dependent resistance against both fungal and bacterial pathogens.