Engineering Perspectives on Drying Technologies of Medicinal Plants: A Review on Kinetic Modelling and Bioactive Compounds Retention

The Potential of Medicinal Plants and Bioactive Compounds in the Fight Against COVID-19

The medicinal plants industry, particularly in regard to products rich in biologically active substances for maintaining health, has grown by leaps and bounds in the last decade, with sales of over-the-counter drugs containing these substances growing by billions of dollars. Attention has thus also been paid to the safety and effectiveness of these medicines. We are currently witnessing a rapid increase in the number of publications devoted to the development of new separation procedures that are not only fast and cheap but also more efficient and eco-friendlier, improving both yields and quality of extracts quality without using hazardous organic solvents. The new approaches include those that use deep eutectic solvents (DES), which are characterized by unique parameters. In fact, DESs can be used for both the isolation and determination of biologically active substances in medicinal plants. Therefore, the purpose of the review is to gather details on the application of DESs in the separation of bioactive compounds in medicinal plants and to provide a solid background for future research in this area. To cover these aspects, the available data and references in the field of interest are reviewed and summarized.

Sustainable extraction bioactive compounds procedures in medicinal plants based on the principles of green analytical chemistry: A review

Diabetes is a major public health problem in the world. It affects each and every part of the human body and also leads to organ failure. Hence, great progress is made in the field of herbal medicine and diabetic research. Our review will focus on the effect of bioactive compounds of medicinal plants which are used to treat diabetes in India and other countries. Information regarding diabetes, oxidative stress, medicinal plants and bioactive compounds was collected from different search engines like Science direct, Springer, Wiley online library, Taylor and francis, Bentham Science, Pubmed and Google scholar. Data was analyzed and summarized in the review. Anti-diabetic drugs that are in use have many side effects on vital organs like heart, liver, kidney and brain. There is an urgent need for alternative medicine to treat diabetes and their disorders. In India and other countries, herbal medicine was used to treat diabetes. Many herbal plants have antidiabetic effects. The plants like ginger, phyllanthus, gymnea, aswagandha, aloe, hibiscus and curcuma showed significant anti-hyperglycemic activities in experimental models and humans. The bioactive compounds like Allicin, azadirachtin, cajanin, curcumin, querceitin, gingerol possess anti-diabetic, antioxidant and other pharmacological properties. This review focuses on the role of bioactive compounds of medicinal plants in the prevention and management of diabetes. Moreover, our review suggests that bioactive compounds have the therapeutic potential against diabetes. However, further in vitro and in vivo studies are needed to validate these findings.

Medicinal plants play an important role in traditional medicine and new drug development, but the increased use of wild plant-based traditional medicine presents a potential biodiversity conservation threat. A better understanding of environmental factors on bioactive compounds in medicinal plants is necessary to ensure the suitability of cultivation location, the sustainability of market supply, and the future conservation of the wild populations. Gentiana rigescens Franch. ex Hemsl. has been used as a medicinal plant in China for hundreds of years due to containing iridoid glycoside compounds, but we knew little about how these compounds respond to environmental changes. We therefore investigated the accumulation and distribution of four iridoid glycosides (loganic acid, sweroside, swertiamarin, and gentiopicroside) in G. rigescens individuals from 28 wild populations in the elevation range of 1260–2978 m in southwest China. We also analyzed the impact of environmental factors (geography, climate, and soil) on the content of gentiopicroside (the dominant compound) in this species. We found significant variations of the contents of the four iridoid glycosides in each part of G. rigescens among populations (p < 0.05), and the gentiopicroside contents showed higher variability in the aboveground part (stem, leaf, and flower), when compared with the content in root. Meanwhile, the root gentiopicroside content was negatively correlated with the contents in other parts of the plant individual. The masses and mass ratios of the four iridoid glycosides also varied among different plant parts among populations. In roots, gentiopicroside dominated the mass proportion of the four iridoid glycosides, while the mass proportions of the four iridoid glycosides varied differently in other plant parts (stem, leaf, and flower). The gentiopicroside content in the root was negatively correlated with latitude and soil C:N ratio, but it was positively correlated with mean annual precipitation, mean annual temperature, soil N:P ratio, and soil N content. However, the effect of climate change on the quality (gentiopicroside content) of G. rigescens materials may be complicated to predict due to the future global warming and spatial heterogeneity of precipitation on the Yunnan-Guizhou plateau. Our study demonstrates the comprehensive influence of environmental factors on the gentiopicroside contents in G. rigescens. The findings have implications for understanding the environmental impact on the bioactive compounds in medicinal Gentiana plants. Further study is needed on how environmental factors influence on the gene expression of iridoid glycoside biosynthesis.

Variations in the leaf metabolite profile between hydroponic and field grown Moringa oleifera Lam. genotypes

Background: Endophytic bacteria residing within plant tissues play a crucial role in promoting plant health and enhancing the production of secondary metabolites, thereby increasing the therapeutic value of medicinal plants. These bacteria exhibit significant taxonomic diversity and ecological distribution, forming symbiotic relationships with their host plants, ranging from mutualism to commensalism. Methods: This review discusses the ecological niches, diversity, and interactions of endophytic bacteria within various medicinal plants. Sampling of roots, stems, leaves, and other plant tissues was conducted, followed by isolation and identification of bacterial species using molecular techniques. The relationships between endophytic bacteria and their hosts were analyzed through ecological assessments and bioactivity assays. Results: Endophytic bacteria demonstrated substantial diversity, predominantly belonging to phyla such as Proteobacteria, Actinobacteria, and Firmicutes. Notable genera included Bacillus, Pseudomonas, and Streptomyces, which exhibited plant growth-promoting and antimicrobial properties. The study identified specific endophytes that enhanced the production of key bioactive compounds in medicinal plants, contributing to their therapeutic efficacy. Conclusion: The symbiotic relationships between endophytic bacteria and medicinal plants reveal a largely untapped reservoir of bioactive compounds with promising therapeutic applications. Understanding the ecological dynamics and biochemical pathways involved in these interactions offers opportunities for innovative approaches in drug discovery and sustainable agriculture. Future research should focus on characterizing these microbial communities and their metabolites to unlock their full potential in medicine and beyond.

Background: This review examines in vitro techniques for characterizing the pharmacokinetics of medicinal plants, focusing on their role in understanding absorption, distribution, metabolism, and excretion (ADME). The diverse bioactive compounds in medicinal plants highlight the need for robust pharmacokinetic evaluations to ensure their safety and efficacy. Objectives: The objectives were to identify and analyze in vitro techniques applied to medicinal plants' pharmacokinetics, addressing a gap in the literature. Methods: Studies were included based on predefined eligibility criteria: in vitro pharmacokinetic studies involving medicinal plants, focusing on ADME stages. Ex vivo, in vivo, and in silico studies were excluded, along with reviews. Data were collected from the PubMed, Web of Science, and Scopus databases in June 2024 using Health Sciences Descriptors (DeCS) and their MeSH synonyms. The data extracted included study location, plant species, bioactive compounds, in vitro protocols, and ADME characteristics. Results: The review included 33 studies, with most focusing on metabolism (60%), absorption (25%), or a combination of ADME aspects. Techniques like Caco-2 cells, human liver microsomes, and simulated gastric and intestinal fluids were widely used. Conclusions: The findings highlight methodological heterogeneity, including variability in extract preparation, compound concentrations, and experimental conditions, which limits the comparability and clinical applicability of results. Key limitations include the lack of standardized protocols and physiological relevance in in vitro models, underscoring the need for multidisciplinary approaches and integration with in vivo studies.

Background. The ecological and geographical conditions of the habitat may be responsible for the synthesis and accumulation of various bioactive compounds and, therefore, for biological effects, including the antioxidant properties of medicinal plants. Understanding the impact of environmental factors on bioactive compounds in medicinal plants have great importance for choosing a place for growing and harvesting plants with a high content of bioactive compounds, as well as providing the highest quality raw materials in the pharmaceutical industry.&#x0D; Objective. To study the accumulation of iridoids, phenolic compounds and antioxidant activity in G. cruciata plant samples, depending on the growing conditions.&#x0D; Results. The regions of the Republic of Tatarstan with the best quality of medicinal raw materials, as well as factors contributing to the accumulation of various groups of biologically active substances in G. cruciate plants, were identified. Humidity and soil type played a decisive role in the accumulation of iridoids; the synthesis of phenolic compounds was more influenced by humidity than the type of soil. However, since the change in antioxidant activity did not correspond to concentration of phenolic compounds, this may be due to the presence of iridoids, which are considered to be the main substances of the plant of the genus Grecian. Their antioxidant activity has been shown in previous studies. In our studies, soil properties seem to have great influence on the production of studied compounds.&#x0D; Conclusions. Almetevsky and Laishevsky districts can be chosen as the optimal place for growing and collecting medicinal plants G. cruciata L.

Medicinal plants are the chief significant resource of therapeutic drugs for healthcare of the world’s population. Because of their enormous structural diversity and vast array of pharmacological functions, secondary metabolites have become an attractive and imperative basis for research. Bioprocessing has been successful for enhanced secondary metabolite production in numerous cases. Various plant cell culture techniques characterize a probable renewable source of therapeutic compounds, which cannot be produced by chemical synthesis. Therefore, it has been reported as an important step in the direction of industrial production via plant biotechnology. Various biotechnological tools are significant to select, multiply, improve and analyse medicinal plants. In this regard, genetic transformation is a prevailing tool for improved production of novel secondary metabolites. Functional genomics provides high-throughput analysis of multiple genes and their expression that becomes necessary for understanding the regulatory mechanism and biochemical pathways associated with secondary metabolites. Combinatorial biosynthesis is another approach for the production of novel natural products. Here, we present an update on biotechnological approaches that are used for enhanced production of novel bioactive compounds in medicinal plants. The review also gives perspectives on upcoming research in this area.

Drying allows the quick conservation of medicinal properties of herbal materials. However, the instability of bioactive compounds in medicinal plants which exhibit potent antioxidant activity and wide range of pharmacological properties may indicate a sensitivity to different drying treatments. Therefore, the objective of the present study was to determine the effect of shade drying, solar drying and oven drying on bioactive ingredients of five cosmetic potential plant leaves. Leaves of Centella asiatica (L.) Urb., Senna alata (L.) Roxb., Justicia adhatoda L., Ocimum tenuiflorum L., Hibiscus rosa-sinensis L. were dried to a constant weight using shade drier at 30-35 °C, solar drier at 30-40 °C and oven at 40 °C. Aluminum chloride colorimetric assay, Folin- Ciocalteau method, and Phosphomolybdate assay were employed to analyse the total flavonoid content (TFC), total phenolic content (TPC) and total antioxidant capacity (TAC) of ethanolic extracts of leaves respectively. All assays were performed in triplicate. Data was analyzed using one -way ANOVA and Tukey’s multiple comparison method. Results showed that significantly higher TFC, TPC and TAC of solar dried leaves of O. tenuiflorum (758.81±2.05 mg RE/100g DW, 3.54±0.71 mg GAE/100g DW and 22.56±0.38 mg AAE/100g DW respectively) and leaves of H. rosa-sinensis (89.72±1.38 mg RE/100g DW, 23.9±0.06 mg GAE/100g DW and 8.53±0.73 mg AAE/100g DW respectively). Solar dried C. asiatica and S. alata leaves showed high TFC and TAC while the TPC was high in oven dried leaves of C. asiatica and shade dried leaves of S. alata respectively. In contrast, J. adhatoda showed the maximum TFC in shade dried samples, the highest TPC in solar dried leaves and the maximum TAC in oven dried leaves. Moreover, there were no significant differences (p > 0.05) among drying methods in terms of antioxidant capacity and phenolic content of J. adhatoda. and antioxidant capacity of C. asiatica. Thus, it can be concluded that, solar drying of medicinal plant materials using solar drier would be an economical, efficient, and effective drying method for preserving bioactive compounds present in leaves of above-mentioned plants.

Bioassay-guided fractionation is the principal method for the identification of active constituents in medicinal plants. By design, this method aims to identify the most active compound in a complex mixture with the objective of discovering novel drug candidates. Described here is a complementary method for the identification of known bioactive compounds in medicinal plants which is untargeted and which takes advantage of the large NMR database of known natural products and availability of statistical software. This untargeted bioassay strategy is demonstrated as a proof of principle in the determination of the antidiabetic compounds in Vitex negundo L. Crude methanol and ethanol extracts, and chloroform, ethyl acetate and aqueous fractions of V. negundo L. were prepared and tested for their in vitro antidiabetic potential using the glucose diffusion retardation assay and the in vitro starch-amylase inhibition assay. The same crude extracts and fractions were profiled using 13C nuclear magnetic resonance (NMR) spectroscopy. The 13C NMR spectra of twelve known compounds from the semi-polar fraction of V. negundo – two iridoids, seven iridoid glucosides, two flavonoids and one flavonoid C-glucoside – were matched from the 13C NMR spectra of the extracts and fractions. The 13C NMR match factor values of the twelve compounds were used in the multivariate correlation analysis with antidiabetic activity using the glucose diffusion retardation activity and the starch-amylase inhibition assay. This method was able to correlate the seven iridoid glucosides with the antidiabetic activity, a result that would have been difficult to obtain using bioassay-guided fractionation.

Bangladesh is abundant in medicinal plants. The bioactive compounds in medicinal plants provide novel therapeutic opportunity of improving human health. But, the benefit-risk balance is usually less considered during formulation of traditional medicine. However, the plants that we included in this study are not studied regarding their hemolytic and anti-venom properties. Thus, we aimed to evaluate and compare the hemolytic activity, antioxidant activity, and phospholipase A2 (PLA2) enzyme neutralization efficacy of aqueous and methanolic extracts of eight known medicinal plants including Asparagus racemosus (root), Withania somnifera (root), Syzygium cumini (leaf), Psidium guajava (leaf), Basella alba (leaf and seed), Morus indica (leaf), M. laevigata (leaf), and M. latifolia (leaf). The results of the hemolytic activity test suggested that the methanolic extracts of S. cumini, P. guajava, B. alba (leaf and seed), M. indica, M. laevigata, and M. latifolia showed significantly higher hemolytic activity compared to their aqueous extracts. The methanolic extracts of A. racemosus, W. somnifera, P. guajava, M. laevigata, and M. latifolia showed remarkable antioxidant activity. Moreover, the results of the PLA2 enzyme neutralization activity test revealed that both aqueous and methanolic extracts of P. guajava, S. cumini, and B. alba (leaf) have significant PLA2 neutralization capacity. Altogether, the aqueous extracts of all plants, except A. racemosus root, have ignorable hemolytic effect. Additionally, P. guajava and S. cumini leaf aqueous extracts have promising PLA2 inhibitory effect and may become the potential source of bioactive compounds for anti-venom drug development.

The identification of bioactive compounds in medicinal plants provides valuable insights into their therapeutic potential, especially for chronic diseases like diabetes. This study conducted a comprehensive Gas Chromatography-Mass Spectrometry (GC-MS) analysis to characterize the phytochemical profile of the aqueous leaf extract of Vernonia amygdalina, a plant widely utilized in traditional medicine across West Africa. GC-MS analysis identified key bioactive compounds, including alkaloids, flavonoids, saponins, and sesquiterpenes, known for their anti-diabetic, antioxidant, and anti-inflammatory properties. These phytochemicals are associated with glucose regulation, oxidative stress reduction, and improved liver and kidney function markers. However, the semi-quantitative analysis based on peak area percentages highlights the need for more rigorous quantification methods. Furthermore, the absence of preclinical and clinical trials, along with a lack of toxicity data, limits the full assessment of its therapeutic potential. The results emphasize the need for safety and efficacy studies to support Vernonia amygdalina’s development as a therapeutic agent for diabetes management.

This review highlights the critical role of chemotaxonomy in the identification, authentication, and discovery of bioactive compounds in medicinal plants. By analyzing secondary metabolites using techniques like UV spectroscopy, FTIR, HPLC, GC-MS, NMR, LC-MS-Qtof, and MALDI-TOF MS, chemotaxonomy ensures accurate plant identification, supporting the safe and effective use of plants in herbal medicine. Key secondary metabolites used in chemotaxonomic identification include alkaloids, flavonoids, terpenoids, phenolics, tannins, and plant peptides. Chemotaxonomy also facilitates the discovery of novel compounds with therapeutic potential, contributing to drug development. The integration of chemotaxonomy with genomics and proteomics allows a deeper understanding of plant biosynthesis and the mechanisms behind bioactive compound production. However, challenges due to variability in metabolite profiles and the lack of standardized methods remain, and future research should focus on developing global databases, improving standardization, and incorporating artificial intelligence and machine learning to enhance plant identification and bioactive compound discovery. The integration of chemotaxonomy with personalized medicine offers the potential to tailor plant-based therapies to individual genetic profiles, advancing targeted treatments. This review underscores chemotaxonomy’s importance in bridging traditional knowledge and modern science, offering sustainable solutions for medicinal plant use and drug development.