Imidacloprid, acephate, and carbaryl are common insecticides that are extensively used in planting mango, a well-known fruit in Vietnam, to ease mango hopper issues. The accurate detection of pesticide residues is critical for mango export to meet quality criteria. This study developed a novel SERS platform by using polydimethylsiloxane (PDMS) to simulate the rose petal structure incorporated with a silver coating layer and silver nanoparticles (AgNPs) to detect imidacloprid, acephate, and carbaryl in mango fruits. In this paper, the rose petal PDMS/Ag-AgNPs replica was considered the most efficient substrate for SERS measurement with an EF of 4.7 × 10⁷. The Raman spectra of the three insecticides obtained from the PDMS/Ag-AgNPs substrate were clearly observed with their characteristic peaks of 1105 cm⁻¹ for imidacloprid, 1083 cm⁻¹, and 1579 cm⁻¹ for acephate, and 727 cm⁻¹ and 1378 cm⁻¹ for carbaryl. The application of PDMS/Ag-AgNPs substrate in quantitative analysis of the three pesticides in mango fruit was evaluated. As a result, the limit of detection was 0.02 mg/kg for imidacloprid, 5 × 10⁻⁵ mg/kg for acephate, and 5 × 10⁻³ mg/kg for carbaryl. The SERS result also revealed that the pesticide residues in the mango sample were within an acceptable limit. This suggested the possibility of the rose petal PDMS/Ag-AgNPs replica for rapid quantification of pesticide residues not only in mango fruit but also in many other agricultural products.

Polyscias fruticosa (L.) Harms is commonly used for medicinal purposes in Vietnam. In traditional medicine, the plant is used to cure ischemia, reduce inflammation, and increase cerebral blood circulation. Triterpene saponins are the major chemical constituents found in the roots of P. fruticosa. This compound exhibited a broad spectrum of biological effects, including lowering blood sugar, suppressing tumor growth and inflammation. This study focused on optimizing the process of total saponins extraction from P. fruticosa roots using the ultrasonic-assisted extraction (UAE) method, ethanol solvent and response surface methodology, and Box–Behnken design model, then evaluating the cytotoxic effect against some cancer cell lines. The results showed that under the optimal conditions, including an extraction temperature of 60 °C and ultrasonic power of 185 W in 65 min, the maximum extraction yield and total saponin content were 14.51 ± 1.15% and 41.24 ± 1.68 mg/g, respectively. Moreover, the saponin extract had cytotoxic effects against A549, HepG₂, PC-3, and Hela. The results of this study confirmed that triterpene saponin is an important chemical component which is present in a high content in P. fruticosa roots and gives rise to significant biological activities. In addition, UAE can be used as a highly efficient method for triterpene saponins extraction from P. fruticosa roots.

(1) Background: Hedera nepalensis (Araliaceae) is a recognized medicinal plant founded in Asia that has been reported to work in antioxidant, antifungal, antimicrobial, and antitumor capacities. (2) Methods: The subcritical fluid extraction of saponin from Hedera nepalensis leaves and the optimum of the extraction process based on yield of saponin contents (by calculating the hederacoside C contents in dried Hedera nepalensis leaves) are examined by response surface methodology (RSM). Furthermore, the antimicrobial activity of the extract is tested for potential drug applications in the future. (3) Results: Based upon RSM data, the following parameters are optimal: extraction time of 3 min, extraction temperature of 150 °C, and a sample/solvent ratio of 1:55 g/mL. Under such circumstances, the achieved yield of saponin is 1.879%. Moreover, the extracts inhibit the growth of some bacterial strains (Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenza) at a moderate to strong level with inhibition zone diameter values ranging from 12.63 to 19.50 mm. (4) Conclusions: The development of such a model provides a robust experimental process for optimizing the extraction factors of saponin contents from Hedera nepalensis extract using subcritical fluid extraction and RSM. Moreover, the current work reveals that saponin extracts of Hedera nepalensis leaves exhibit a potential antimicrobial activity, which can be used as scientific evidence for further study.