Optimization and validation of the protocol used to analyze the taste of traditional Chinese medicines using an electronic tongue

Electronic eye and electronic tongue data fusion combined with a GETNet model for the traceability and detection of Astragalus

BACKGROUND

Astragalus is a widely used traditional Chinese medicine material that is easily confused due to its quality, price and other factors derived from different origins. This article describes a novel method for the rapid tracing and detection of Astragalus via the joint application of an electronic tongue (ET) and an electronic eye (EE) combined with a lightweight convoluted neural network (CNN)-transformer model. First, ET and EE systems were employed to measure the taste fingerprints and appearance images, respectively, of different Astragalus samples. Three spectral transform methods - the Markov transition field, short-time Fourier transform and recurrence plot - were utilized to convert the ET signals into 2D spectrograms. Then, the obtained ET spectrograms were fused with the EE image to obtain multimodal information. A lightweight hybrid model, termed GETNet, was designed to achieve pattern recognition for the Astragalus fusion information. The proposed model employed an improved transformer module and an improved Ghost bottleneck as its backbone network, complementarily utilizing the benefits of CNN and transformer architectures for local and global feature representation. Furthermore, the Ghost bottleneck was further optimized using a channel attention technique, which boosted the model's feature extraction effectiveness.

RESULTS

The experiments indicate that the proposed data fusion strategy based on ET and EE devices has better recognition accuracy than that attained with independent sensing devices.

CONCLUSION

The proposed method achieved high precision (99.1%) and recall (99.1%) values, providing a novel approach for rapidly identifying the origin of Astragalus, and it holds great promise for applications involving other types of Chinese herbal medicines. © 2024 Society of Chemical Industry.

Taste Sensor Assessment of Bitterness in Medicines: Overview and Recent Topics

In recent decades, taste sensors have been increasingly utilized to assess the taste of oral medicines, particularly focusing on bitterness, a major obstacle to patient acceptance and adherence. This objective and safe method holds promise for enhancing the development of patient-friendly medicines in pharmaceutical companies. This review article introduces its application in measuring the intensity of bitterness in medicine, confirming the achievement of taste masking, distinguishing taste differences between branded and generic medicines, and identifying substances to suppress bitterness in target medicines. Another application of the sensor is to predict a significant increase in bitterness when medicine is taken with certain foods/beverages or concomitant medication. Additionally, to verify the sensor's predictability, a significant correlation has been demonstrated between the output of a bitter-sensitive sensor designed for drug bitterness (BT0) and the bitterness responses of the human taste receptor hT2R14 from BitterDB (huji.ac.il). As a recent advancement, a novel taste sensor equipped with lipid/polymer membranes modified by 3-Br-2,6-dihydroxybenzoic acid (2,6-DHBA), based on the concept of allostery, is introduced. This sensor successfully predicts the bitterness of non-charged pharmaceuticals with xanthine skeletons, such as caffeine or related compounds. Finally, the future prospects of taste sensors are discussed.

The material basis of bitter constituents in Carbonized Typhae Pollen, based on the integration strategy of constituent analysis, taste sensing system and molecular docking

The discovery of bitter constituents is of great significance to the exploration of medicinal substances for they have potential physiological effects. Carbonized Typhae Pollen (CTP), which is a typical example of carbonized Traditional Chinese Medicine (TCM), has a bitter taste and hemostatic effect after carbonized processing. The objective of this study is to elucidate the material basis of bitter constituents in CTP. Firstly, the constituents of CTP extracts with 7 different solvents were characterized by UPLC-Q-TOF-MS. Then, multivariate statistical analysis was used to visualize the CTP extracts from 7 solvents. A total of 37 constituents were tentatively identified and 17 constituents were considered as the key constituents in differentiating 7 different solvent extracts. Subsequently, the bitter evaluation of extracts from different polar parts was investigated by using an electronic tongue. As a result, the order of bitterness of the extracts was as follows: ethanol > methanol > water > n-butyl alcohol > petroleum ether > butyl acetate > isopropanol. There were statistically significant differences in the bitter degree of extracts. By correlation analysis of bitter information and chemical constituents with partial least squares regression (PLSR), 8 potential bitterness constituents were discovered, including phenylalanine, valine, chlorogenic acid, isoquercitrin, palmitic acid, citric acid, quercetin-3-O-(2-α-L-rhamnosyl)-rutinoside, and typhaneoside. Additionally, molecular docking analysis was conducted to reveal the interaction of these constituents with the bitter taste receptor. The docking result showed that these constituents could be embedded well into the active pocket of T2R46 and had significant affinity interactions with critical amino acid residues by forming hydrogen bonds. This study provided a reliable theoretical basis for future research on biological activity of bitterness substances.

Recent Advances in Bitterness-Sensing Systems

Bitterness is one of the basic tastes, and sensing bitterness plays a significant role in mammals recognizing toxic substances. The bitter taste of food and oral medicines may decrease consumer compliance. As a result, many efforts have been made to mask or decrease the bitterness in food and oral pharmaceutical products. The detection of bitterness is critical to evaluate how successful the taste-masking technology is, and many novel taste-sensing systems have been developed on the basis of various interaction mechanisms. In this review, we summarize the progress of bitterness response mechanisms and the development of novel sensors in detecting bitterness ranging from commercial electronic devices based on modified electrodes to micro-type sensors functionalized with taste cells, polymeric membranes, and other materials in the last two decades. The challenges and potential solutions to improve the taste sensor quality are also discussed.

No ambiguity: Chemosensory-based ayurvedic classification of medicinal plants can be fingerprinted using E-tongue coupled with multivariate statistical analysis

Background: Ayurveda, the indigenous medical system of India, has chemosensory property (rasa) as one of its major pharmacological metric. Medicinal plants have been classified in Ayurveda under six rasas/tastes—sweet, sour, saline, pungent, bitter and astringent. This study has explored for the first time, the use of Electronic tongue for studies of rasa-based classification of medicinal plants.

Methods: Seventy-eight medicinal plants, belonging to five taste categories (sweet, sour, pungent, bitter, astringent) were studied along with the reference taste standards (citric acid, hydrochloric acid, caffeine, quinine, L-alanine, glycine, β-glucose, sucrose, D-galactose, cellobiose, arabinose, maltose, mannose, lactose, xylose). The studies were carried out with the potentiometry-based Electronic tongue and the data was analysed using Principle Component Analysis, Discriminant Function Analysis, Taste Discrimination Analysis and Soft Independent Modeling of Class Analogy.

Results: Chemosensory similarities were observed between taste standards and the plant samples–citric acid with sour group plants, sweet category plants with sucrose, glycine, β-glucose and D-galactose. The multivariate analyses could discriminate the sweet and sour, sweet and bitter, sweet and pungent, sour and pungent plant groups. Chemosensory category of plant (classified as unknown) could also be identified.

Conclusion: This preliminary study has indicated the possibility of fingerprinting the chemosensory-based ayurvedic classification of medicinal plants using E-tongue coupled with multivariate statistical analysis.

Challenges in using Electronic tongue to study rasa of plants: II. Impact of solvent and concentration on sensor response and taste ranking

Background

Although Electronic tongue is used in pharmaceutical, food and beverage industries for objective evaluation of taste, its use in medicinal plants from an ayurvedic perspective is novel. Control experiments are therefore necessary to standardise and optimise parameters.

Objective

The aim is to optimise the use of solvent and standardise sample concentration for study of plants from an ayurvedic standpoint of rasa. The major objectives are two-fold: (i) evaluate sensor response to different types of solvent water (ii) explore use of E-tongue in taste ranking of medicinal plants used in ayurveda.

Materials and methods

Single, double and triple distilled, reverse osmosis and milliQ waters were evaluated separately and as a medium for preparing plant extracts. For taste ranking, standard addition method using d-glucose as sweet taste standard was used for different brands of mango juices (case in point study) and eight medicinal plants from sweet category. The effect of sample concentration and taste standard on taste ranking were evaluated.

Results

MQ and TD water demonstrated similar organoleptic properties whereas plant extracts prepared in DD and MQ water showed maximum taste-based differentiation. The mango juices were taste discriminated by E-tongue and ranked based on their sweetness scores. The relative ranking of plant samples showed concentration dependence and also varied with the concentration range of taste standard.

Conclusion

Milli-Q and double distilled water can be used for E-tongue studies of medicinal plants. While the results open up the possibility of taste ranking of medicinal plants, they also demonstrate the importance of standardising and optimising the concentration of samples and taste standards in the context of ayurvedic rasa based studies.

Taste masking and rheology improvement of drug complexed with beta-cyclodextrin and hydroxypropyl-β-cyclodextrin by hot-melt extrusion

This study aimed to mask fluconazole (FLU) taste and improve its rheological properties by an efficient process of cyclodextrin complexation. For this, hot-melt extrusion (HME) was used to obtain extrudates composed of FLU, hydroxypropylcellulose, and one of two different cyclodextrins (β-cyclodextrin or hydroxypropyl-β-cyclodextrin) maintaining the drug:cyclodextrin molar ratio at 1:0.3 or 1:0.2, respectively. Samples were characterized by physicochemical tests, palatability using e-tongue and antifungal assays. Drug stability was preserved after HME, according to spectroscopy test (correlation coefficient >0.9) and HPLC-assay (100-107%). Flowability was improved in HME systems with compressibility of <12%. Similarly, floodability exhibited significant enhancement (dispersibility <10%). Whereas extrudates of FLU containing only the polymeric matrix led to a slow drug dissolution efficiency (18.6%) and a partial drug taste masking; extrudates containing cyclodextrin accelerated FLU dissolution (dissolution efficiency approx. 30%) and provided a complete drug taste masking. Moreover, HME process could produce drug complexes with high complexation efficiency and preserve its antifungal activity.

Hot Melt Extrudates Formulated Using Design Space: One Simple Process for Both Palatability and Dissolution Rate Improvement

This work aimed at obtaining an optimized itraconazole (ITZ) solid oral formulation in terms of palatability and dissolution rate by combining different polymers using hot melt extrusion (HME), according to a simplex centroid mixture design. For this, the polymers Plasdone^® (poly(1-vinylpyrrolidone-co-vinyl acetate) [PVP/VA]), Klucel^® ELF (2-hydroxypropyl ether cellulose [HPC]), and Soluplus^® (SOL, polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol) were processed using a laboratory HME equipment operating without recirculation at constant temperature. Samples were characterized by physicochemical assays, as well as dissolution rate and palatability using an e-tongue. All materials became homogeneous and dense after HME processing. Thermal and structural analyses demonstrated drug amorphization, whereas IR spectroscopy evidenced drug stability and drug-excipient interactions in HME systems. Extrudates presented a significant increase in dissolution rate compared to ITZ raw material, mainly with formulations containing PVP/VA and HPC. A pronounced improvement in taste masking was also identified for HME systems, especially in those containing higher amounts of SOL and HPC. Data showed polymers act synergistically favoring formulation functional properties. Predicted best formulation should contain ITZ 25.0%, SOL 33.2%, HPC 28.9%, and PVP/VA 12.9% (w/w). Optimized response considering dissolution rate and palatability reinforces the benefit of polymer combinations.