Chemical Constituents and Biological Activities of Plants from the Genus Viola

Diversity analysis of endophytes with antimicrobial and antioxidant potential from Viola odorata: an endemic plant species of the Himalayas

Viola odorata, also known as "Banafshah" in high altitudes of Himalayas, is well known for its pharmaceutical importance in Ayurvedic and Unani medicinal system. The plant is a source of various drugs for its anti-inflammatory, diaphoretic, diuretic, emollient, expectorant, antipyretic, and laxative properties. The endophytes of plants have been reported for their role in modulating various physiological and biological processes of the host plants. In the present study, a total of 244 endophytes were isolated in pure cultures from the roots of Viola odorata, and genetic diversity was evaluated using amplified ribosomal DNA restriction analysis (ARDRA) and enterobacterial repetitive intergenic consensus (ERIC). The molecular fingerprinting revealed variation among various rRNA types among morphologically different endophytes based on ARDRA and ERIC-PCR. The screening of endophytes showed antimicrobial activity of 11 bacterial isolates and one actinomycete SGA9 against various pathogens Bacillus cereus, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis. The antioxidant activity revealed the majority of the bacterial isolates able to scavenge the free radical in the range of 10-50% and 8 bacterial isolates in the range of 50-85%. Principal component analysis separated eight isolates away from the central eclipse and form a separate group based on antimicrobial and antioxidant potential. The identification of these eight isolates showed affiliation with different species of the genus Enterobacter, Microbacterium, Pseudomonas, Rhizobium, and Streptomyces. This is the first report on the characterization of endophytic bacteria and actinomycetes from endemic Viola odorata. Results suggested that these endophytes could be explored for the production of antimicrobial and antioxidant products.

A comprehensive review of phytochemistry, pharmacology and quality control of plants from the genus Viola

OBJECTIVES

The genus Viola belongs to the family Violaceae, and the plants from this genus are essential folk herb medicine extensively used in many areas. The plants from the genus Viola are used to treat various diseases and exert a significant role in protecting people's health. This review summarized the genus Viola plants' phytochemistry, pharmacology, and quality control methods.

KEY FINDINGS

The information on chemical constituents and pharmacological effects of the genus Viola was obtained by searching the Web of Science, Pubmed, CNKI, and other databases. A total of 208 valuable articles were selected and analyzed in this review. The main chemical components of plants from the genus Viola consist of flavonoids, coumarins, alkaloids, lignans, sesquiterpenes, cyclotides, etc. The active chemical components of medicinal plants from this genus exert antibacterial, antiviral, antioxidant, anti-inflammatory, anti-tumor, neuroprotective, hepatoprotective activities, and so on. The quality control of these plants is not sufficient and needs further research.

SUMMARY

The chemical constituents, pharmacological effects, and quality control of plants from the genus Viola were systematically summarized in this paper, and this review provides a literature basis for the further research of plants from this genus.

Viola betonicifolia-Mediated Biosynthesis of Silver Nanoparticles for Improved Biomedical Applications

We report the biosynthesis of silver (Ag) nanoparticles (NAPs) (LEVB-Ag NAPs) by an environmentally friendly green synthesis approach using the phytoconstituents of Viola betonicifolia leaf extract. The spectroscopic techniques were employed to characterize biosynthesized LEVB-Ag NAPs successfully. Biosynthesized LEVB-Ag NAPs were assessed for antibacterial and antimycotic activities against bacterium and mycological strains (H. pylori, S. epidermidis, C. tropicalis, and T. rubrum) using the serial dilution method. They were also evaluated for their biofilm inhibiting potential against both bacterial and fungi species. They were further assessed for the cytobiocompatible potential with two normal cell lines (293T and hMSC). The results demonstrate that the biosynthesized LEVB-Ag NAPs showed superior log₁₀ reduction in bacterial and fungal growth and presented more than 99.50% killing efficiency. Moreover, biosynthesized LEVB-Ag NAPs excellently inhibited the biofilm formation of bacterial (Gram-positive and Gram-negative) and mycological strains and presented more than 80% biofilm inhibiting percentage compared to both plant extract and CHE-Ag NAPs. They further presented good cytobiocompatibility in vitro with 293T and hMSC cells compared to CHE-Ag NAPs. Biosynthesized LEVB-Ag NAPs presented superior antibacterial, antimycotic, biofilm inhibition, and cytobiocompatible results that might be attributed to the synergistic effect of the NAPs’ physiochemical properties and the immobilized phytoconstituents from plant leaf extract on their surface. Hence, biosynthesized LEVB-Ag NAPs may be a promising contender for a variety of therapeutic applications.

An integrated study of Violae Herba (Viola philippica) and five adulterants by morphology, chemical compositions and chloroplast genomes: insights into its certified plant origin

BACKGROUND

Viola philippica Cav. is the only original plant for Violae Herba, as described in the Chinese Pharmacopoeia. The quality of this crude drug is affected by several adulterants from congeneric Viola species, and the authentic plant origin of Violae Herba is still controversial. Genome-based identification offers abundant genetic information and potential molecular markers that can be used for the authentication of closely related species. This study aims to investigate the certified origin of Violae Herba and to develop more effective markers for these easily confused species at the genetic level.

METHODS

We compared the morphology and chemical composition of 18 batches of commercial samples and six widespread medicinal Viola plants used as Violae Herba or its substitutes by TLC and HPLC-Triple-TOF-MS/MS analyses. The complete chloroplast genomes of these species were sequenced and analyzed, including the general features, repeat sequences, mutational hotspots and phylogeny. The complete chloroplast genomes used as superbarcodes and some specific barcodes screened from mutational hotspots were tested for their ability to distinguish Viola species.

RESULTS

A comparative study showed that Violae Herba is a multi-origin traditional Chinese medicine. Commercial decoction pieces and the standard reference drug were mainly derived from V. prionantha, clashing with the record in the Chinese Pharmacopoeia. Chloroplast genome analyses of V. philippica and five adulterants indicated that sequence divergence was relatively low within Viola species. By tree-based approaches, the complete chloroplast genomes showed a better discrimination ability and phylogenetic resolution for each Viola species. These results indicate that the whole chloroplast genomes can be used as superbarcodes to differentiate Viola medicinal plants. More specific DNA barcodes could be further developed from the Viola chloroplast genomes for more efficient and rapid identification of commercial Violae Herba and its adulterants.

CONCLUSIONS

This study has implications for chloroplast genome-based phylogenetic analysis and the authentication of multiple Viola species used as Violae Herba. The legal origin recorded in the Chinese Pharmacopoeia should be further revised to V. prionantha, in line with the commercial Violae Herba in the TCM markets.

Biogenic Synthesis of MnO2 Nanoparticles With Leaf Extract of Viola betonicifolia for Enhanced Antioxidant, Antimicrobial, Cytotoxic, and Biocompatible Applications

In this study, we propose to synthesize NPs using plant extract containing active biomedical components, with the goal of obtaining NPs that inherit the biomedical activities of the plant. Herein, we report the synthesis of manganese dioxide nanoparticles (VBLE-MnO₂ NPs) using the leaves extract of Viola betonicifolia, in which the biological active plant's secondary metabolites function as both reducing and capping agents. The synthesized NPs were successfully characterized with different spectroscopic techniques. The antibacterial, antifungal, and biofilm inhibition properties of the synthesized VBLE-MnO₂ NPs were further explored against a variety of bacteria (Gram-positive and Gram-negative) and mycological species. Additionally, their antioxidant ability against linoleic acid peroxidation inhibition, cytobiocompatibility with hMSC cells, and cytotoxicity against MCF-7 cells were investigated compared to leaves extract and chemically synthesized manganese dioxide NPs (CH-MnO₂ NPs). The results were demonstrated that the synthesized VBLE-MnO₂ NPs presented excellent antibacterial, antifungal, and biofilm inhibition performance against all the tested microbial species compared to plant leaves extract and CH-MnO₂ NPs. Moreover, they also exhibited significant antioxidant potential, which was comparable to the external standard (ascorbic acid); however, it was higher than plant leaves extract and CH-MnO₂ NPs. Furthermore, the synthesized CH-MnO₂ NPs displayed good cytobiocompatibility with hMSC cells compared to CH-MnO₂ NPs. The enhanced antioxidant, antibacterial, antifungal, and biofilm inhibition efficacy as compared to CH-MnO₂ NPs might be attributed to the synergistic effect of the VBLE-MnO₂ NPs' physical properties and the adsorbed biologically active phytomolecules from the leaves extract of V. betonicifolia on their surface. Thus, our study establishes a novel ecologically acceptable route for nanomaterials' fabrication with increased and/or extra medicinal functions derived from their herbal origins.

Green Synthesized Gold Nanoparticles Using Viola betonicifolia Leaves Extract: Characterization, Antimicrobial, Antioxidant, and Cytobiocompatible Activities

Introduction

Viola betonicifolia is a rich source of numerous secondary metabolites, such as alkaloids, flavonoids, tannins, phenolic compounds, saponins, triterpenoids, and so on, that are biologically active towards different potential biomedical applications. To broaden the potential use of Viola betonicifolia in the realm of bionanotechnology, we investigated the plant's ability to synthesize gold nanoparticles (Au NPs) in a green and efficient manner for the very first time.

Methods

The gold nanoparticles (VB-Au NPs) were synthesized using the leaves extract of Viola betonicifolia, in which plant's secondary metabolites function as both reducing and capping agents. The VB-Au NPs were successfully characterized with spectroscopic techniques. The antimicrobial properties of the VB-Au NPs were further explored against bacterial and mycological species. Additionally, their antioxidant, cytotoxic, and cytobiocompatibility properties were examined in vitro against linoleic acid peroxidation, MCF-7 cancer cells, and human mesenchymal stem cells (hMSCs), respectively.

Results

Results demonstrated that VB-Au NPs presented excellent antibacterial, antifungal, and biofilm inhibition performance against all the tested microbial species compared to plant leaves extract and commercially purchased chemically synthesized gold NPs (CH-Au NPs). Moreover, they also exhibited significant antioxidant potential, comparable to the external standard. The VB-Au NPs displayed good cytobiocompatibility with hMSCs and demonstrated excellent cytotoxic potential against MCF-7 cancer cells compared to CH-Au NPs. The current work presents a green method for synthesizing VB-Au NPs with enhanced antioxidant, antimicrobial, cytotoxic and biofilm inhibition efficacy compared to CH-Au NPs might be attributed to the synergistic effect of the nanoparticle's physical properties and the adsorbed biologically active phytomolecules from the plant leaves extract on their surface.

Conclusion

Thus, our study establishes a novel ecologically acceptable route for nanomaterials' fabrication with increased and/or extra medicinal functions derived from their herbal origins.

Protective Effect of n-Butanol Extract from Viola yedoensis on Immunological Liver Injury

Viola yedoensis Makino was used to treat inflammation, viral hepatitis, acute pyogenic infection, and ulcerative carbuncles. However, the protective effect on immunological liver injury (ILI) of V. yedoensis had been rarely reported. This study aimed to explore the protective effect of n-butanol extract (BE) from V. yedoensis on ILI in vitro and in vivo. In vitro, the BE significantly inhibited the secretions of Hepatitis B surface antigen (HBsAg) and Hepatitis B e antigen (HBeAg) in the HepG2.2.15 cells and the replication of HBV DNA. The research data in vivo revealed that the BE reduced the levels of alanine transaminase (ALT), aspartate transaminase (AST), and methane dicarboxylic aldehyde (MDA) in liver tissues of the ConA-induced mice, while increased the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and the effective contents of tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ) and the BE could ameliorate liver histological lesions. These results motivated a further investigation into the chemical constituents of BE. Four coumarins (esculetin, prionanthoside, cichoriin, and esculin) and one flavonoid (quercetin-3-O-galactoside) were isolated from the BE by silica gel column chromatography and recrystallization, of which structures were eventually confirmed by ¹ H-NMR, ¹³ C-NMR, and MS.

A Comprehensive Review on Chemical and Pharmacological Potential of Viola betonicifolia: A Plant with Multiple Benefits

Viola betonicifolia (Violaceae) is commonly recognized as “Banafsha” and widely distributed throughout the globe. This plant is of great interest because of its traditional, pharmacological uses. This review mainly emphases on morphology, nutritional composition, and several therapeutic uses, along with pharmacological properties of different parts of this multipurpose plant. Different vegetative parts of this plant (roots, leaves, petioles, and flowers) contained a good profile of essential micro- and macronutrients and are rich source of fat, protein, carbohydrates, and vitamin C. The plant is well known for its pharmacological properties, e.g., antioxidant, antihelminthic, antidepressant, anti-inflammatory, analgesic, and has been reported in the treatment of various neurological diseases. This plant is of high economic value. The plant has potential role in cosmetic industry. This review suggests that V. betonicifolia is a promising source of pharmaceutical agents. This plant is also of significance as ornamental plant, however further studies needed to explore its phytoconstituents and their pharmacological potential. Furthermore, clinical studies are needed to use this plant for benefits of human beings.

Hepatoprotective effect of the solvent extracts of Viola canescens Wall. ex. Roxb. against CCl4 induced toxicity through antioxidant and membrane stabilizing activity

Background

Viola canescens Wall. ex. Roxb. exhibits analgesic, antimalarial and antispasmodic activities. It is used folklorically for the treatment of liver diseases, hypertension, malaria and cancer. The current study investigates phytochemical constituents, antioxidant and hepatoprotective activity of solvent extracts of whole plant of Viola canescens.

Methods

Phytochemicals, acute toxicity study and antioxidant activity of Viola canescens methanolic extract (VCME), ethyl acetate fraction (EAF), and partially purified EAF (90% EAF and combination of 80% EAF + 20% methanol fraction (EAF + Me) was carried out. Hepatoprotective activity of VCME, EAF (200 and 400 mg/kg body weight) and partially purified EAF (50 mg/kg body weight) was investigated in carbon tetrachloride (CCl₄) intoxicated BALB/c mice for 7 days. Membrane stabilization effect was determined by hypotonic solution induced hemolysis while DNA ladder assay was carried out by polyacrylamide gel electrophoresis.

Results

Phytochemical screening of VCME showed the presence of alkaloids, phenols, flavonoids, saponins, carbohydrates, tannins and triterpenes. VCME, EAF (at 200 and 400 mg/kg body weight) and partially purified EAF (90% EAF and EAF + Me) at 50 mg/kg body weight significantly reduced the level of ALT, ALP, total bilirubin and restored the level of serum protein in comparison to CCl₄ treated group. A significant reduction in malondialdehyde (MDA) and elevation in catalase (CAT) and superoxide dismutase (SOD) level was observed in extract treated animals as compared to CCl₄ (p < 0.05). The IC₅₀ values in membrane stabilization potential for VCME, EAF and sodium salicylate were 3.7 ± 0.11, 3.4 ± 0.15 and 3.2 ± 0.09 mg/ml, respectively. Similarly, CCl₄ induced degradation of DNA was counteracted by VCME and EAF. The liver biopsy of mice treated with the solvent extracts showed remarkable restoration of normal histological archeitecture.

Conclusions

Viola canescens showed significant hepatoprotective potential due to its antioxidant and membrane stabilization effect.