Transformation of Lettuce with rol ABC Genes: Extracts Show Enhanced Antioxidant, Analgesic, Anti-Inflammatory, Antidepressant, and Anticoagulant Activities in Rats

Enterohemorrhagic Escherichia coli O157:H7 antigens produced in transgenic lettuce effective as an oral vaccine in mice

KEY MESSAGE

Transgene with recombination sites to address biosafety concerns engineered into lettuce to produce EspB and γ-intimin C280 for oral vaccination against EHEC O157:H7. Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a food-borne pathogen where ruminant farm animals, mainly bovine, serve as reservoirs. Bovine vaccination has been used to prevent disease outbreaks, and the current method relies on vaccines subcutaneously injected three times per year. Since EHEC O157:H7 colonizes mucosal surfaces, an oral vaccine that produces an IgA response could be more convenient. Here, we report on oral vaccination against EHEC O157:H7 in mice orally gavaged with transgenic lettuce that produces EHEC O157:H7 antigens EspB and γ-intimin C280. Younger leaves accumulated a higher concentration of antigens; and in unexpanded leaves of 30-day-old T2 plants, EspB and γ-intimin C280 were up to 32 and 51 μg/g fresh weight, respectively. Mice orally gavaged with lettuce powders containing < 3 µg antigens for 6 days showed a mucosal immune response with reduced colonization of EHEC O157:H7. This suggests that the transgenic lettuce has potential to be used for bovine vaccination. To promote the biosafety of crop plants producing medically relevant proteins, recombination sites were built into our transgenic lines that would permit optional marker removal by Cre-lox recombination, as well as transgene deletion in pollen by CinH-RS2 recombination. The ability to upgrade the transgenic lettuce by stacking additional antigen genes or replacing older genes with newer versions would also be possible through the combined use of Bxb-att and Cre-lox recombination systems.

Lettuce as an Effective Remedy in Uremic Pruritus: Review of the Literature Supplemented by an In Silico Study

Uremic pruritus is a frequent and prominent symptom in patients with advanced or end-stage renal disease. Lack of an effective treatment for kidney disease-associated pruritus often leads to many problems for these patients and makes it difficult to choose an appropriate treatment. The purpose of this evidence-based hypothesis is to share the scientific reasons and related mechanisms in order to claim that lettuce could be useful in the treatment of uremic pruritus. This hypothesis is based on studies related to lettuce and its anti-inflammatory, antioxidant, antidiabetic, sedative, hypnotic, nephroprotective, potassium balancing, and blood purification properties. As a result, we suggest that lettuce could be a good choice for improving and reducing uremic pruritus due to its certain characteristics. Although proof of this hypothesis requires further clinical trial studies, this hypothesis can nevertheless lead to formulating an appropriate therapy for uremic-induced pruritus. By conducting a molecular docking study, we investigated the interactions between nineteen natural bioactive components of lettuce (Lactuca sativa L.) and human kappa opioid receptors. The in silico docking studies revealed that most of the ligands showed better antipruritic efficacy than gabapentin. Gamma-tocopherol, delta-tocopherol, and campesterol demonstrated the highest binding affinities toward the target protein.

In vitro and in vivo evaluations of antioxidative, anti-Alzheimer, antidiabetic and anticancer potentials of hydroponically and soil grown Lactuca sativa

BACKGROUND

Lactuca sativa is an edible plant commonly used by local communities to manage diabetes and stomach problems.

METHODS

This work aimed to investigate the anti-oxidant, anticancer, antidiabetic and Anti-Alzheimer effects of hydroponically (HyL) and soil-grown (SoL) Lactuca sativa. Streptozotocin-induced diabetes and AlCl3-induced Alzheimer's disease model was used to evaluate the medicinal effects of Lactuca sativa.

RESULTS

HyL showed significant activity in lipid peroxidation assay, DPPH and DNA protection assay, while SoL extract showed moderated activity, respectively. A similar activity response was quantified for α-glucosidase, α-amylase, acetylcholinesterase and butyrylcholinesterase inhibition assays. The cytotoxic potential of HyL and SoL extracts against MCF7, and HePG2 cancer cell lines exhibited significant activity. HyL and SoL showed a substantial decrease in blood glucose levels in streptozotocin-induced diabetic rats. Diabetes-related liver/kidney biomarkers and anti-oxidant enzyme trends moved toward normal after HyL and SoL treatment. In Anti-Alzheimer's based Morris water and elevated plus maze tests, HyL and SoL displayed memory-enhancing response and anti-anxiety behaviour, respectively. HPLC quantification of dopamine and serotonin revealed a moderate but significant (p<0.05) increase in the level of these neurotransmitters in HyL and SoL groups.

CONCLUSION

Overall, the study revealed that hydroponic Lactuca sativa possesses the therapeutic potential to treat diseases like Alzheimer's and diabetes.

Antibacterial, Antihemolytic, Cytotoxic, Anticancer, and Antileishmanial Effects of Ajuga bracteosa Transgenic Plants

Herbal and traditional medicines can play a pivotal role in combating cancer and neglected tropical diseases. Ajuga bracteosa, family Lamiaceae, is an important medicinal plant. The genetic transformation of A. bracteosa with rol genes of Agrobacterium rhizogenes further enhances its metabolic content. This study aimed at undertaking the molecular, phytochemical, and in vitro biological analysis of A. bracteosa extracts. We transformed the A. bracteosa plant with rol genes and raised the regenerants from the hairy roots. Transgenic integration and expression of rolB were confirmed by conventional polymerase chain reaction (PCR) and qPCR analysis. The methanol: chloroform crude extracts of wild-type plants and transgenic regenerants were screened for in vitro antibacterial, antihemolytic, cytotoxic, anticancer, and leishmanial activity. Among all plants, transgenic line 3 (ABRL3) showed the highest expression of the rolB gene. Fourier transform infra-red (FTIR) analysis confirmed the enhanced number of functional groups of active compounds in all transgenic lines. Moreover, ABRL3 exhibited the highest antibacterial activity, minimum hemolytic activity (CC₅₀ = 7293.05 ± 7 μg/mL) and maximum antileishmanial activity (IC₅₀ of 56.16 ± 2 μg/mL). ABRL1 demonstrated the most prominent brine shrimp cytotoxicity (LD₅₀39.6 ± 4 μg/mL). ABRL3 was most effective against various human cancer cell lines with an IC₅₀ of 57.1 ± 2.2 μg/mL, 46.2 ± 1.1 μg/mL, 72.4 ± 1.3 μg/mL, 73.3 ± 2.1 μg/mL, 98.7 ± 1.6 μg/mL, and 97.1 ± 2.5 μg/mL against HepG2, LM3, A549, HT29, MCF-7, and MDA-MB-231, respectively. Overall, these transgenic extracts may offer a cheaper therapeutic source than the more expensive synthetic drugs.

Polyphenol Rich Ajuga bracteosa Transgenic Regenerants Display Better Pharmacological Potential

Ajuga bracteosa Wall. ex Benth. is an endangered medicinal herb traditionally used against different ailments. The present study aimed to create new insight into the fundamental mechanisms of genetic transformation and the biological activities of this plant. We transformed the A. bracteosa plant with rol genes of Agrobacterium rhizogenes and raised the regenerants from the hairy roots. These transgenic regenerants were screened for in vitro antioxidant activities, a range of in vivo assays, elemental analysis, polyphenol content, and different phytochemicals found through HPLC. Among 18 polyphenolic standards, kaempferol was most abundant in all transgenic lines. Furthermore, transgenic line 3 (ABRL3) showed maximum phenolics and flavonoids content among all tested plant extracts. ABRL3 also demonstrated the highest total antioxidant capacity (8.16 ± 1 μg AAE/mg), total reducing power, (6.60 ± 1.17 μg AAE/mg), DPPH activity (IC50 = 59.5 ± 0.8 μg/mL), hydroxyl ion scavenging (IC50 = 122.5 ± 0.90 μg/mL), and iron-chelating power (IC50 = 154.8 ± 2 μg/mL). Moreover, transformed plant extracts produced significant analgesic, anti-inflammatory, anticoagulant, and antidepressant activities in BALB/c mice models. In conclusion, transgenic regenerants of A. bracteosa pose better antioxidant and pharmacological properties under the effect of rol genes as compared to wild-type plants.

Effects of Green Lettuce Leaf Extract on Sleep Disturbance Control in Oxidative Stress-Induced Invertebrate and Vertebrate Models

This study investigated the effect of ethanol-extracted green lettuce leaf (GLE) on sleep behavior in physical stress-induced invertebrate and vertebrate models. In Drosophila melanogaster, the group that experienced vibration stress showed decreased sleep time compared to the no-vibration-stress control group, but the GLE treatment group recovered this lost sleep time. The GLE group also recovered the gene expression of downregulated superoxide dismutase induced by vibration stress conditions. According to electroencephalography analysis of rats, non-rapid eye movement (NREM) sleep significantly decreased with a decrease in sleep time for the group in which immobilization stress was induced. In the GLE group (120 mg/kg), the change in sleep pattern caused by stress was restored, and NREM sleep increased by 68.8%, improving overall sleep quality. In addition, GLE upregulated the expression levels of oxidation-related factors and γ-aminobutyric acid (GABA_A) receptor. Quercetin-3-glucuronide (Q3G) was evaluated as a sleep-promoting active substance contained in GLE using the pentobarbital-induced sleep test and showed the effect of prolonged sleep time. Q3G inhibited [³H]-flumazenil binding in a concentration-dependent manner with GLE. Taken together, the results indicate that GLE effectively binds to the GABA_A receptor to promote sleep, demonstrating the potential of Q3G as an active substance.

Novel piperazine-2,5-dione analogs bearing 1H-indole: Synthesis and biological effects

In this work, a series of novel piperazine-2,5-dione derivatives bearing indole analogs (2a-2q) was designed and synthesized. The synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR spectroscopy, and ESI-MS. They were then evaluated for their anti-depressant, anti-inflammatory, and analgesic activities in vivo. The experimental results revealed that all the compounds showed clear anti-depressant, anti-inflammatory, and analgesic effects at a dose of 10 mg/kg. Among them, compounds 2e and 2q exhibited the best anti-depressant effects (the percent decreases in the duration of immobility were 70.2% and 71.2%, respectively), which were similar to that of fluoxetine (67.9%) in the forced swim test. Additionally, compounds 2e and 2q also displayed good anti-inflammatory and analgesic activities. Literature reports have highlighted the anti-inflammatory and analgesic effects of anti-depressant drugs, suggesting that they may have a similar mechanism of action. Therefore, further studies to investigate the possible mechanisms of action of compounds 2e and 2q are warranted.

Genetic transfection, hairy root induction and solasodine accumulation in elicited hairy root clone of Solanum erianthum D. Don

An efficient genetic transfection technique has been established using A4 strain of Agrobacterium rhizogenes for the first time in a medicinally valuable plant Solanum erianthum D. Don. The explants were randomly pricked with sterile needle, inoculated with bacterial suspension. The infected leaves were then washed and transferred to MS basal medium fortified with cefotaxime for hairy root induction. A maximum transformation efficiency of 72 % has been recorded after two days of co-cultivation period. The transfer of rolA and rolB genes from the bacterium to the plant genome has been confirmed in five transformed hairy rootlines by standard Polymerase Chain Reaction technique. On the basis of growth analysis and secondary metabolite study two potential rhizoclones (A4-HR-A and A4-HR-B) were selected. Rhizoclone A4-HR-A can produce highest amount of alkaloid, phenolic and flavonoid, whereas A4-HR-B was observed to be highest tannin producer. Alkaloid like solasodine, commercially important for steroidal drug synthesis, was quantified from leaf and A4-HR-A clone by an improved High Performance Liquid Chromatography method. This showed a sustainable increase (1.33 fold) in production of solasodine in hairy rootline.

Phytochemicals, Nutritional Value, Antioxidant, and Anticoagulant Activity of Lactuca sativa L. Leaves and Stems

The main ingredient in the daily salad dish is the leaves of Lactuca sativa, while the stems are usually discarded and not eaten. This study was conducted to compare the stems and leaves of two selected L. sativa varieties (L. sativa var. longifolia L. and L. sativa var. capitata L.) related to the preliminary phytochemical investigation, nutrient content, DPPH assay, and in vitro anticoagulant activity by determination of prothrombin time (PT) and activated partial thromboplastin time (aPTT). The findings revealed almost the same phytoconstituents in the leaves and stems of each variety, such as terpenoids, flavonoids, coumarins, and others. Exceptionally, tannins have only been detected in the leaves. Compared to the stems, the leaves of both varieties showed statistically significantly higher levels of raw protein and raw fat. For the DPPH assay, the leaves of both varieties have a statistically significantly higher antioxidant activity than the stems. The leaves and stem extract of the two selected varieties showed a significant prolongation of PT (P <0.05 vs. NS= 12:30 s). On the other hand, the aPTT test showed a significant increase in aPTT (P <0.05 vs. NS = 32:44 s) in the stem extract of both varieties, whereas there was no statistically significant increase in aPTT in the leaves of both varieties. Both parts of each variety have a diversity of phytochemicals and nutrients. The leaves of both varieties have a higher antioxidant activity than the stems. While the stems had higher anticoagulant activity than the leaves.

Agrobacterium rhizogenes-mediated transformation enhances the antioxidant potential of Artemisia tilesii Ledeb

Plants belonging to the genus Artemisia L. have been used for medicinal purposes since ancient times. These aromatic plants produce and accumulate a wide range of potent secondary metabolites, many of which have shown antioxidant, antiparasitic, antimicrobial, anti-inflammatory, and even anticancer activities. Enhanced biosynthesis of these compounds is a prerequisite for comprehensive studies of their therapeutic properties and cost-efficient use. Transformation of plants with Agrobacterium rhizogenes native root locus (rol) genes is a promising approach to increase the biosynthesis of plant secondary metabolites. The aim of the present study was to evaluate the effects of A. rhizogenes-mediated transformation on the flavonoid contents in hairy roots of medicinal herb A. tilesii Ledeb. Transgenic A. tilesii hairy root lines were analyzed for stable integration of the rolB and rolC transgenes into the plant genome, total flavonoid contents, antioxidant activities of extracts, and the spatiotemporal expression of two flavonoid biosynthetic genes, phenylalanine ammonialyase (PAL) and chalcone synthase (CHS). The flavonoid contents of A. tilesii directly correlated with the antiradical activity and reducing power of their respective lines, with the greatest antioxidant activity found in the plants with the highest level of total flavonoids. Furthermore, all hairy root lines demonstrated altered expression of plant native PAL and CHS genes. Most importantly, A. rhizogenes-mediated transformation enhanced the biosynthesis of natural antioxidants in A. tilesii, producing almost twice the amount of flavonoids than controls. These findings provide an opportunity for the identification of the bioactive molecules in A. tilesii extracts and their potential health benefits.

Screening of chalcone analogs with anti-depressant, anti-inflammatory, analgesic, and COX-2-inhibiting effects

A group of 2-methyl-4-phenylquinoline-chalcone analogs (2a-2x) was synthesized and investigated for anti-depressant, anti-inflammatory, and analgesic effects as cyclooxygenase-2 inhibitors. Pharmacological experiments identified 24 analogs that exhibited anti-depressant, anti-inflammatory, and analgesic activities. In particular, compounds 2c, 2k, and 2w markedly shortened immobility times and exhibited the most anti-depressant activity. In addition, the mechanisms of action of the analogs 2c, 2k, and 2w were likely related to increased serotonin levels in the central nervous system. Compounds 2c, 2k, and 2w displayed reasonable cyclooxygenase-2 inhibitory effects (IC₅₀ values from 0.21 to 0.29 µmol/L) similar to celecoxib (IC₅₀: 0.19 µmol/L) in vitro. A molecular docking study of compound 2k also was conducted.

Optimization of cell suspension culture of transformed and untransformed lettuce for the enhanced production of secondary metabolites and their pharmaceutical evaluation

In vitro suspension culture techniques are cost effective for large-scale production of secondary metabolites. In the present study, firstly, suspension cultures of untransformed Lactuca sativa were prepared using different hormonal combinations and were subjected to different pH, temperature and salt concentrations. Maximum biomass was obtained for suspensions supplemented with 1.5 mg/L BAP and 0.1 mg/L NAA, at pH 5.8, temperature 28 °C and 0 mM NaCl concentration. Using these parameters, suspensions were produced for rol ABC- and rol C-transformed lines of L. sativa. All the transgenic lines showed prominent increase in fresh weight (FW) and dry weight (DW) with maximum values for rol ABC2 line producing 169.8 mg/mL FW and 25.3 mg/mL DW. The exudates of transformed and untransformed plants were tested for the antioxidant activity and in vivo assays on rats. Maximum phenolic content (261 μg/mL) and flavonoid content (637.6 μg/mL) were obtained for rol C1 transgenic line. Total antioxidant capacity was found maximum (1451.7 μg/mL) for untransformed lettuce, whereas rol C1 showed maximum total reducing power activity (637.6 μg/mL). In DPPH assay, maximum activity (104.7 μg/mL) was shown by rol ABC3 line. In rats analgesic assay, maximum activity (74.9%) was shown by rol C2. Line rol C1 showed maximum anti-inflammatory activity (69.2%) and maximum antidepressant activity (minimum immobility time of 55 s). Maximum anticoagulant activity was observed for rol ABC2 with maximum clotting time of 130 s. The present study could help in using lettuce suspension culture as platform for the enhanced production of important metabolites.

The Health Promoting Bioactivities of Lactuca sativa can be Enhanced by Genetic Modulation of Plant Secondary Metabolites

Plant secondary metabolites are protective dietary constituents and rol genes evidently increase the synthesis of these versatile phytochemicals. This study subjected a globally important vegetable, lettuce (Lactuca sativa) to a combination of untargeted metabolomics (LC-QTof-MS) and in vitro bioactivity assays. Specifically, we examined the differences between untransformed cultured lettuce (UnT), lettuce transformed with either rolABC (RA) or rolC (RC) and commercially grown (COM) lettuce. Of the 5333 metabolite features aligned, deconvoluted and quantified 3637, 1792 and 3737 significantly differed in RA, RC and COM, respectively, compared with UnT. In all cases the number of downregulated metabolites exceeded the number increased. In vitro bioactivity assays showed that RA and RC (but not COM) significantly improved the ability of L. sativa to inhibit α-glucosidase, inhibit dipeptidyl peptidase-4 (DPP-4) and stimulate GLP-1 secretion. We putatively identified 76 lettuce metabolites (sesquiterpene lactones, non-phenolic and phenolic compounds) some of which were altered by several thousand percent in RA and RC. Ferulic acid levels increased 3033–9777%, aminooxononanoic acid increased 1141–1803% and 2,3,5,4′tetrahydroxystilbene-2-O-β-d-glucoside increased 40,272–48,008%. Compound activities were confirmed using commercially obtained standards. In conclusion, rol gene transformation significantly alters the metabolome of L.sativa and enhances its antidiabetic properties. There is considerable potential to exploit rol genes to modulate secondary metabolite production for the development of novel functional foods. This investigation serves as a new paradigm whereby genetic manipulation, metabolomic analysis and bioactivity techniques can be combined to enable the discovery of novel natural bioactives and determine the functional significance of plant metabolites.

Flavonoid content and antioxidant activity of Artemisia vulgaris L. "hairy" roots

We investigated the effect of Agrobacterium rhizogenes-mediated transformation on antioxidant activity of Artemisia vulgaris "hairy" roots. It appeared that transformation may increase flavonoid content as well as DPPH-scavenging activity and ability to reduce Fe³⁺ as compared to the non-transformed plants. Some "hairy" roots accumulated flavonoids up to 73.1 ± 10.6 mg RE/g DW (while the amount of flavonoids in the leaves of non-transformed plants was up to 49.4 ± 5.0 mg RE/g DW). DPPH-scavenging activity of some "hairy" root lines was 3-3.8 times higher than such one of the roots of the control plants. The Fe³⁺-reducing power of most transgenic root extracts exceeded such power of the extracts of the roots of the control plants. The decrease in SOD activity was found in the most "hairy" root lines compared to the control roots. The increase of flavonoid content correlated with the increase of ability of extracts to scavenge DPPH*- radical and Fe³⁺ - reducing power. No correlation between SOD activity of extracts and concentration of flavonoids was found (p ≥ 0.2).Thus, transformation has led to the alteration in flavonoid accumulation and antioxidant activity in A. vulgaris "hairy" roots. Transgenic roots with high-antioxidant properties can be selected after A. rhizogenes-mediated transformation.

Five Indigenous Plants of Pakistan with Antinociceptive, Anti-Inflammatory, Antidepressant, and Anticoagulant Properties in Sprague Dawley Rats

Five medicinal plants of Pakistan were investigated for their antinociceptive, anti-inflammatory, antidepressant, and anticoagulant potential. Antinociceptive activity was estimated by hot plate and writhing assay. In hot plate assay, Quercus dilatata (52.2%) and Hedera nepalensis (59.1%) showed moderate while Withania coagulans (65.3%) displayed a significant reduction in pain. On the other hand, in writhing assay, Quercus dilatata (49.6%), Hedera nepalensis (52.7%), and Withania coagulans (62.0%) showed comparative less activity. In anti-inflammatory assays crude extracts showed significant edema inhibition in a dose dependent manner. In carrageenan assay, the highest activity was observed for Withania coagulans (70.0%) followed by Quercus dilatata (66.7%) and Hedera nepalensis (63.3%). Similar behavior was observed in histamine assay with percentage inhibitions of 74.3%, 60.4%, and 63.5%, respectively. Antidepressant activity was estimated by forced swim test and the most potent activity was revealed by Withania coagulans with immobility time 2.2s (95.9%) followed by Hedera nepalensis with immobility time 25.3s (53.4%). Moreover, the crude extracts of Fagonia cretica (74.6%), Hedera nepalensis (73.8%), and Phytolacca latbenia (67.3%) showed good anticoagulant activity with coagulation times 86.9s, 84.3s, and 67.5s, respectively. Collectively, the results demonstrate that these five plants have rich medicinal constituents which can be further explored.

Genetic Transformation and Hairy Root Induction Enhance the Antioxidant Potential of Lactuca serriola L

Lactuca serriola L. is a herbaceous species, used for human nutrition and medicinal purposes. The high antioxidant capacity of L. serriola indicates the possibility of enhancing its edible and health potential by increasing the flavonoid and phenolic contents. The present study aimed at enhancing the production of phenolics and flavonoids by hairy root cultures in Lactuca serriola transformed with Agrobacterium rhizogenes strain AR15834 harbouring the rolB gene. The genetic transformation of rolB in transformed roots was validated, and rolB expression level was evaluated using real-time qPCR analysis. Expression levels of flavonoid biosynthesis genes (CHI, PAL, FLS, and CHS) were assessed in the hairy and nontransformed roots. Results showed higher expression levels in the transgenic roots than in the nontransformed ones (p < 0.01). Transgenic hairy roots exhibited a 54.8-96.7% increase in the total phenolic content, 38.1-76.2% increase in the total flavonoid content, and 56.7-96.7% increase in the total reducing power when compared with the nontransgenic roots (p < 0.01). DPPH results also revealed that the transgenic hairy roots exhibited a 31.6-50% increase in antioxidant potential, when compared to normal roots. This study addressed the enhancement of secondary metabolite biosynthesis by hairy root induction in L. serriola.