Insecticidal Activity and Insecticidal Mechanism of Total Saponins from Camellia oleifera

Natural products from Camellia oleifera fruit and its comprehensive utilisation

Camellia oleifera (C. oleifera) is a woody oil plant with a good reputation of 'Oriental Olive Oil' in China. The national understanding of the health-care benefits of Camellia oil are already widespread, but the production of C. oleifera fruit has not been achieved large-scale industrialisation. In this review, we focus on the properties and commercial value of its natural products, and processing technology, performance characterisation, and novel modification strategies of its processed products. In addition, we briefly summarised the research progress of breeding and put forward the comprehensive utilisation of C. oleifera fruit based on the tandem of extraction and processing. This review might attract more researchers to make profound study regarding it as an alternative of olive oil.

Development of a Safe and Effective Bacillus thuringiensis-Based Nanobiopesticide for Controlling Tea Pests

Mg(OH)2 was used as the nanocarrier of the Bacillus thuringiensis (Bt) Cry1Ac protein, and the synthesized Cry1Ac-Mg(OH)2 composites were regular and uniform nanosheets. Nano-Mg(OH)2 could effectively improve the insecticidal effect of the Cry1Ac protein toward Ectropis obliqua. It could enhance the damage degree of the Cry1Ac protein to intestinal epithelial cells and microvilli, induce and enrich the production of reactive oxygen species (ROS) in the midgut, and enhance the degradation of the Cry1Ac protein into active fragments. Furthermore, an anti-rinsing assay showed that the Cry1Ac-Mg(OH)2 composites were bound to the notch structure of the tea leaf surface. The retention of the Cry1Ac protein increased by 11.45%, and sprayed nano-Mg(OH)2 was rapidly absorbed by different tissues of tea plants. Moreover, nano-Mg(OH)2 and composites did not significantly affect non-target organisms. These results show that nano-Mg(OH)2 can serve as a safe and effective biopesticide carrier, which provides a new approach for stable and efficient Bt preparation.

Discovery of New Botanical Insecticides: Identification and Insecticidal Activity of Saponins from Clematis obscura Maxim and Insights into the Stress Response of Acyrthosiphon pisum Harris

To discover new botanical products-based insecticide candidates, 14 triterpenoid saponins (1-14) including four new ones, obscurosides A-D (1-4), were isolated from Clematis obscura Maxim as potential agrochemicals against Acyrthosiphon pisum Harris and Plutella xylostella (L.). Compounds 1-3 were characterized by a rare ribose substitution at C-3, and 4 was a bidesmoside glycosylated at the rare C-23 and C-28 positions of the oleanane aglycone. Compounds 10 (median antifeeding concentration, AFC50 = 1.10 mg/mL; half-lethal concentration, LC50 = 1.21 mg/mL) and 13 (AFC50 = 1.09 mg/mL, LC50 = 1.37 mg/mL) showed significant insecticidal activities against third larvae of P. xylostella at 72 h. All saponins displayed antifeedant activities against A. pisum with the deterrence index of 0.20-1.00 at 400 μg/mL. Compound 8 showed optimal oral toxicity (LC50 = 50.09 μg/mL) against A. pisum, followed by compounds 1, 5-7, 9, and 14 (LC50 = 90.21-179.25 μg/mL) at 72 h. The shrinkage of the cuticle and the destruction of intestinal structures of microvilli, nucleus, endoplasmic reticulum, and mitochondria were toxic symptoms of 8-treated A. pisum. The significantly declined Chitinase activity in 8-treated A. pisum with an inhibition rate of 79.1% at LC70 (70% lethal concentration) could be the main reason for its significant oral toxicities. Molecular docking revealed favorable affinities of compounds 1 and 8 with group I Chitinase OfChtI (Group I Chitinase from Ostrinia furnacalis) through conventional hydrogen bonds and alkey/π-alkey interactions by different patterns. These results will provide valuable information for the development of novel botanical pesticides for the management of insect pests, especially against A. pisum.

Antibacterial and antibiofilm effects of Camellia oleifera seed dreg extract and its application in cosmetics

BACKGROUND

Cosmetic care products contain a high proportion of water and nutrients. Therefore, preventing bacterial growth is an important issue to ensure product quality and safety. The application of antibacterial natural ingredients derived from plants is considered to have the potential to maintain product quality and reduce the use of chemicals in formulations. Additionally, chemically synthesized antiseptic and antibacterial agents are widely used in the industry at present. However, some preservative ingredients have been reported that may cause skin irritation, redness, allergies, and even dermatitis.

AIMS

This study aimed to prepare extract from Camellia oleifera tea seed dregs (CTSD), investigate the antibacterial effects on two pathogenic bacteria and evaluate the product preservative ability.

METHODS

Ethanol extraction was prepared and subjected to characterize their triterpenoid contents. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum biofilm eradication concentration (MBEC) were determined for Pseudomonas aeruginosa and Staphylococcus aureus. The product's stability and preservative qualities, along with its ability to scavenge free radicals through antioxidant activity, were also assessed.

RESULTS

The gram-positive S. aureus showed greater susceptibility to the treatment. In additional, CTSD possessed significant free radical scavenging activity in vitro and cultured normal human skin fibroblast CCD-966SK cells under nontoxic concentration. The challenge test and accelerated storage test confirmed the CTSD containing formulated emulsion is eligible for commercialization.

CONCLUSIONS

CTSD has the potential to be developed as an alternative agent to control microbial biofilm formation, or can be used as an adjuvant compound for infectious disease control.

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.

Applications of Chinese Camellia oleifera and its By-Products: A Review

Camellia oleifera is a woody oil tree species unique to China that has been cultivated and used in China for more than 2,300 years. Most biological research on C. oleifera in recent years has focused on the development of new varieties and breeding. Novel genomic information has been generated for C. oleifera, including a high-quality reference genome at the chromosome level. Camellia seeds are used to process high-quality edible oil; they are also often used in medicine, health foods, and daily chemical products and have shown promise for the treatment and prevention of diseases. C. oleifera by-products, such as camellia seed cake, saponin, and fruit shell are widely used in the daily chemical, dyeing, papermaking, chemical fibre, textile, and pesticide industries. C. oleifera shell can also be used to prepare activated carbon electrodes, which have high electrochemical performance when used as the negative electrode of lithium-ion batteries. C. oleifera is an economically valuable plant with diverse uses, and accelerating the utilization of its by-products will greatly enhance its industrial value.

Increased Tea Saponin Content Influences the Diversity and Function of Plantation Soil Microbiomes

Plant secondary metabolites (PSMs) can affect the structures and functions of soil microbiomes. However, the core bacteria associated with PSMs, and their corresponding functions have not been explored extensively. In this study, soil physicochemical properties, tea saponin (TS) contents, microbial community compositions, and microbial community functions of different-age Camellia oleifera plantation soils from representative regions were analyzed. We evaluated the effects of plantation age increase on PSM accumulation, and the subsequent consequences on the structures and functions of soil microbiomes. Plantation ages increase positively correlated with accumulated TS contents, negative effects on soil physicochemical properties, and soil microbiome structures and functions. Clearly, the core functions of soil microbiomes transitioned to those associated with PSM metabolisms, while microbial pathways involved in cellulose degradation were inhibited. Our study systematically explored the influences of PSMs on soil microbiomes via the investigation of key bacterial populations and their functional pathways. With the increase in planting years, increased TS content simplified soil microbiome diversity, inhibited the degradation of organic matter, and enriched the genes related to the degradation of TS. These findings significantly advance our understanding on PSMs-microbiome interactions and could provide fundamental and important data for sustainable management of Camellia plantations.

IMPORTANCE Plant secondary metabolites (PSMs) contained in plant litter will be released into soil with the decomposition process, which will affect the diversity and function of soil microbiomes. The response of soil microbiomes to PSMs in terms of diversity and function can provide an important theoretical basis for plantations to put forward rational soil ecological management measures. The effects of planting years on PSM content, soil physicochemical properties, microbial diversity, and function, as well as the interaction between each index in Camellia oleifera plantation soil are still unclear. We found that, with planting years increased, the accumulation of tea saponin (TS) led to drastic changes in the diversity and function of soil microbiomes, which hindered the decomposition of organic matter and enriched many genes related to PSM degradation. We first found that soil bacteria, represented by Acinetobacter, were significantly associated with TS degradation. Our results provide important data for proposing rational soil management measures for pure forest plantations.

Anti-Hyperglycemic Effects of Refined Fractions from Cyclocarya paliurus Leaves on Streptozotocin-Induced Diabetic Mice

To identify the chemical components responsible for the anti-hyperglycemic effect of Cyclocarya paliurus (Batal.) Iljinsk (Juglandaceae) leaves, an ethanol extract (CPE) and a water extract (CPW) of C. paliurus leaves, as well as their total flavonoids (CPF), triterpenoids (CPT) and crude polysaccharides (CPP), were prepared and assessed on streptozotocin (STZ)-induced diabetic mice. After being orally administrated once a day for 24 days, CPF (300 mg/kg), CPP (180 mg/kg), or CPF+CPP (300 mg/kg CPF + 180 mg/kg CPP) treatment reversed STZ-induced body weight and muscle mass losses. The glucose tolerance tests and insulin tolerance tests suggested that CPF, CPP, and CPF+CPP showed anti-hyperglycemic effect in STZ-induced diabetic mice. Furthermore, CPF enhances glucose-stimulated insulin secretion in MIN6 cells and insulin-stimulated glucose uptake in C2C12 myotubes. CPF and CPP suppressed inflammatory cytokine levels in STZ-induced diabetic mice. Additionally, CPF and CPP improved STZ-induced diabetic nephropathy assessed by H&E staining, blood urea nitrogen content, and urine creatinine level. The molecular networking and Emperor analysis results indicated that CPF showed potential anti-hyperglycemic effects, and HPLC–MS/MS analysis indicated that CPF contains 3 phenolic acids and 9 flavonoids. In contrast, CPT (650 mg/kg) and CPC (300 mg/kg CPF + 180 mg/kg CPP + 650 mg/kg CPT) did not show anti-hyperglycemic effect. Taken together, polysaccharides and flavonoids are responsible for the anti-hyperglycemic effect of C. paliurus leaves, and the clinical application of C. paliurus need to be refined.

Plant-Derived Pesticides as an Alternative to Pest Management and Sustainable Agricultural Production: Prospects, Applications and Challenges

Pests and diseases are responsible for most of the losses related to agricultural crops, either in the field or in storage. Moreover, due to indiscriminate use of synthetic pesticides over the years, several issues have come along, such as pest resistance and contamination of important planet sources, such as water, air and soil. Therefore, in order to improve efficiency of crop production and reduce food crisis in a sustainable manner, while preserving consumer's health, plant-derived pesticides may be a green alternative to synthetic ones. They are cheap, biodegradable, ecofriendly and act by several mechanisms of action in a more specific way, suggesting that they are less of a hazard to humans and the environment. Natural plant products with bioactivity toward insects include several classes of molecules, for example: terpenes, flavonoids, alkaloids, polyphenols, cyanogenic glucosides, quinones, amides, aldehydes, thiophenes, amino acids, saccharides and polyketides (which is not an exhaustive list of insecticidal substances). In general, those compounds have important ecological activities in nature, such as: antifeedant, attractant, nematicide, fungicide, repellent, insecticide, insect growth regulator and allelopathic agents, acting as a promising source for novel pest control agents or biopesticides. However, several factors appear to limit their commercialization. In this critical review, a compilation of plant-derived metabolites, along with their corresponding toxicology and mechanisms of action, will be approached, as well as the different strategies developed in order to meet the required commercial standards through more efficient methods.

Design, synthesis and insecticidal activity of novel analogues of flubendiamide containing alkoxyhexafluoroisopropyl groups

Flubendiamide has received considerable attention in the agriculture field due to its novel mode of action and excellent insecticidal activity. However, the high cost and toxicity to aquatic invertebrates associated with flubendiamide limit its agronomic utility. On the basis of the structure of the lead compound, flubendiamide, we designed and synthesized a series of novel analogues of flubendiamide bearing a alkoxyhexafluoroisopropyl moiety using 2-methyl-4-(2-alkoxyhexafluoroisopropyl) anilines as the key intermediates. Their insecticidal activities against the oriental armyworm (Mythimna separata Walker) were evaluated. The results indicated that most of the target compounds exhibited high insecticidal activities. Specifically, compound 8h showed the best insecticidal activity against the armyworm and its insecticidal activity reached 70% at 0.156 mg L-1. The LC50 value of compound 8h (0.0512 mg L-1) is nearly the same as the corresponding commercial product flubendiamide (0.0412 mg L-1). Furthermore, the acute toxicity test showed that the 48 h LC50 values of compound 8h and flubendiamide against Daphnia magna Straus were 0.0066 and 0.0021 mg L-1, respectively. The toxicity of compound 8h is obviously lower than flubendiamide.