Metabolic Profiling, GC-MS, LC-ESI-MS/MS Analysis, Phenolics Isolation and Biological Evaluation of the Aerial Parts Extracts of Felicia abyssinica L.

Felicia abyssinica L., family Asteraceae, is widely used in folk medicine. This represents the first study to investigate its phytoconstituents and pharmacological effects. Phytoconstituents identified by GC-MS, LC-ESI-MS/MS-based metabolomics, and NMR (1D & 2D). GC-MS of the (FAMEs) revealed mainly the identification of 55 fatty acids. LC-ESI-MS/MS analysis resulted in the tentative identity of 13 compounds representing flavonoids, phenolics, and fatty acids. Ethyl acetate fraction exhibited the highest total flavonoids 66.19 mg/mL Rutin equivalent, while the methanolic fraction showed the highest phenolics 87.70 mg/mL gallic acid equivalent, and the total condensed tannins were 64.35 µg CE/mg catechins equivalent. A flavonoid and a cinnamic acid derivative were identified as quercetin 3-O-(2'''-O-acetyl) rutinoside (Mumikotin A) (1) and Methyl sinapate (2). Biological evaluation of antioxidant and cytotoxic activities was carried out. Cytotoxicity was examined on HepG-2 cell lines where the average cell viability was 91.42 % and 52.48 % for concentrations 10 and 100 µg/mL respectively. Methylene chloride and methanolic fractions showed the highest antioxidant activity 225 µg/mL Ascorbic acid equivalents. It is hypothesized that high phenolics, flavonoid content, and oxygenated identified compounds contribute to the antioxidant activity and can be regarded as a promising species for nutraceuticals active antioxidants with potential value for remedy.

3-Acetyl-11-keto-ß-boswellic Acid-Based Hybrids Alleviate Acetaminophen-Induced Hepatotoxicity in HepG2 by the Regulation of Inflammatory and Oxidative Stress Pathways: An Integrated Approach.

In an effort to develop new compounds for managing drug-induced liver injury, we prepared 23 novel hybrids based on 3-acetyl-11-keto-ß-boswellic acid (AKBA) using various biocompatible linkers. A bioguided approach was employed to identify the most promising hybrid. Eight compounds exhibited superior anti-inflammatory activity compared to the parent compound. Two of these hybrids (5b and 18) were able to reduce gene expression of TNF-α in LPS-induced inflammation in RAW 264.7 cells, similar to dexamethasone. Subsequently, the hepatoprotective potential of these hybrids was evaluated against acetaminophen (APAP) toxicity in HepG2 cells at doses of 1 and 10 µM. Both hybrids effectively restored cytokine levels, which had been elevated by APAP, to normal levels. Furthermore, they normalized depleted superoxide dismutase and reduced glutathione levels while significantly reducing malondialdehyde (MDA) levels. Network pharmacology analysis suggested that AKBA-based hybrids exert their action by regulating PI3K and EGFR pathways, activating anti-inflammatory mechanisms, and initiating tissue repair and regeneration. Molecular docking studies provided insights into the interaction of the hybrids with PI3K. Additionally, the hybrids demonstrated good stability at different pH levels, following first-order kinetics, with relatively long half-lives, suggesting potential for absorption into circulation without significant degradation.

Theophylline-based hybrids as acetylcholinesterase inhibitors endowed with anti-inflammatory activity: synthesis, bioevaluation, in silico and preliminary kinetic studies.

In this study, we investigated the conjugation of theophylline with different compounds of natural origin hoping to construct new hybrids with dual activity against cholinergic and inflammatory pathways as potential agents for the treatment of Alzheimer's disease (AD). Out of 28 tested hybrids, two hybrids, acefylline-eugenol 6d and acefylline-isatin 19, were able to inhibit acetylcholinesterase (AChE) at low micromolar concentration displaying IC50 values of 1.8 and 3.3 µM, respectively, when compared to the galantamine standard AChE inhibitor. Moreover, the prepared hybrids exhibited a significant anti-inflammatory effect against lipopolysaccharide induced inflammation in RAW 264.7 and reduced nitric oxide (NO), tumor necrosis alpha (TNF-α), interleukin-1ß (IL-1ß), and interleukin-6 (IL-6) levels in a dose dependent manner. These hybrids demonstrated significant reductions in nitric oxide (NO), tumor necrosis alpha (TNF-α), interleukin-1ß (IL-1ß), and interleukin-6 (IL-6) levels in RAW 264.7 cells induced by lipopolysaccharide (LPS). The findings of this study were further explained in light of network pharmacology analysis which suggested that AChE and nitric oxide synthase were the main targets of the most active compounds. Molecular docking studies revealed their ability to bind to the heme binding site of nitric oxide synthase 3 (NOS-3) and effectively occupy the active site of AChE, interacting with both the peripheral aromatic subsite and catalytic triad. Finally, the compounds demonstrated stability in simulated gastric and intestinal environments, suggesting potential absorption into the bloodstream without significant hydrolysis. These findings highlight the possible therapeutic potential of acefylline-eugenol 6d and acefylline-isatin 19 hybrids in targeting multiple pathological mechanisms involved in AD, offering promising avenues for further development as potential treatments for this devastating disease.

Identification of sulphonamide-tethered N-((triazol-4-yl)methyl)isatin derivatives as inhibitors of SARS-CoV-2 main protease.

SARS-CoV-2 pandemic in the end of 2019 led to profound consequences on global health and economy. Till producing successful vaccination strategies, the healthcare sectors suffered from the lack of effective therapeutic agents that could control the spread of infection. Thus, academia and the pharmaceutical sector prioritise SARS-CoV-2 antiviral drug discovery. Here, we exploited previous reports highlighting the anti-SARS-CoV-2 activities of isatin-based molecules to develop novel triazolo-isatins for inhibiting main protease (Mpro) of the virus, a crucial enzyme for its replication in the host cells. Particularly, sulphonamide 6b showed promising inhibitory activity with an IC50= 0.249 µM. Additionally, 6b inhibited viral cell proliferation with an IC50 of 4.33 µg/ml, and was non-toxic to VERO-E6 cells (CC50 = 564.74 µg/ml) displaying a selectivity index of 130.4. In silico analysis of 6b disclosed its ability to interact with key residues in the enzyme active site, supporting the obtained in vitro findings.

Anti-cancer effect of nano-encapsulated boswellic acids, curcumin and naringenin against HepG-2 cell line.

BACKGROUND: liver cancer is one of the most common cancers in the world. So far, there is no gold standard treatment for hepatocellular carcinoma. We conducted this in vitro study to assess the effect of three natural products: Boswellic acids, curcumin and naringin versus corresponding nanoparticles (NPs) on Hep G2 cells proliferation. METHODS: Boswellic acid, curcumin, naringin-loaded NPs were prepared using nanoprecipitation method. Human liver (HepG2) cell line was cultured in Dulbecco's modified Eagle's medium (DMEM). The cell growth inhibition and cytotoxicity were evaluated by MTT assay. RESULTS: Boswellic acid, curcumin, naringin were able to inhibit HepG2 cells proliferation. IC50 at 24 h, 48 h showed significant lower values in NPs versus Free herbs. IC50 values of free Boswellic acids and NPs at 24 h were (24.60 ± 1.89 and 7.78 ± 0.54, P < 0.001), at 48 h were (22.45 ± 1.13 and 5.58 ± 0.27, P < 0.001) respectively. IC50 values of free curcumin and NPs at 24 h were (5.89 ± 0.8 and 3.46 ± 0.23, P < 0.05), at 48 h were (5.57 ± 0.94 and 2.51 ± 0.11, P < 0.05), respectively. For free and naringenin NPs, IC50 values at 24 h were (14.57 ± 1.78 and 7.25 ± 0.17, P < 0.01), at 48 h were (11.37 ± 1.45 and 5.21 ± 0.18, P < 0.01) respectively. CONCLUSION: Boswellic acid, curcumin, naringin and their nanoprecipitation prepared nanoparticles suppressed Hep G2 cells proliferation.

Microbial Transformation of the Sesquiterpene Lactone, Vulgarin, by Aspergillus niger.

The biotransformation of vulgarin (1), an eudesmanolides-type sesquiterpene lactone obtained from Artemisia judaica, by the microorganism, Aspergillus niger, was carried out to give three more polar metabolites; 1-epi-tetrahydrovulgarin (1α,4α-dihydroxy-5αH,6,11ßH-eudesman-6,12-olide (2), 20% yield, 1α,4α-dihydroxyeudesm-2-en-5αH,6,11ßH-6,12-olide (3a), 10% yield, and C-1 epimeric mixture (3a, b), 4% yield, in a ratio of 4:1, 3a/3b. The structures of vulgarin and its metabolites were elucidated by 1 and 2D NMR spectroscopy in conjunction with HRESIMS. Metabolites (3a) and (3b) are epimers, and they are reported here for the first time as new metabolites obtained by biotransformation by selective reduction at C-1. Vulgarin and its metabolites were evaluated as anti-inflammatory agents using the human cyclooxygenase (COX) inhibitory assay. The obtained data showed that (1) exhibited a good preferential inhibitory activity towards COX-2 (IC50 = 07.21 ± 0.10) and had a moderate effect on COX-1 (IC50 = 11.32 ± 0.24). Meanwhile, its metabolite (3a) retained a selective inhibitory activity against COX-1 (IC50 = 15.70 ± 0.51). In conclusion, the results of this study revealed the necessity of the presence α, ß unsaturated carbonyl group in (1) for better COX-2 inhibitory activity. On the other hand, the selectivity of (1) as COX-1 inhibitor may be enhanced via the reduction of C-1 carbonyl group.

Bio-evaluation of Untapped Alkaloids from Vinca minor Enriched by Methyl-jasmonate-induced Stress: an Integrated Approach.

The low amount of metabolites isolated from natural products is one of the challenges preventing their biological evaluation. The modulation of biosynthetic pathways by stimulating stress-induced responses in plants was proven to be a valuable tool for diversification of already known natural products. Recently, we reported the dramatic effect of methyl jasmonate (MeJA) on Vinca minor alkaloids distribution. In this study, three compounds identified as 9-methoxyvincamine, minovincinine, and minovincine are successfully isolated in good yield and subjected to several bioassays based on a network pharmacology study. The extracts and isolated compounds show weak to moderate antimicrobial and cytotoxic activities. Also, they are found to significantly promote wound healing in scratch assay, and transforming growth factor-ß (TGF-ß) modulation is suggested to be the potential pathway based on bioinformatic analysis. Hence, Western blotting is used to assess the expression of several markers related to this pathway and wound healing. The extracts and isolated compounds are able to increase the expression of Smad3 and Phosphatidylinositol-3-kinase (PI3K), while downregulating the levels of cyclin D1 and the mammalian target of rapamycin (mTOR) except for minovincine, which increases the mTOR expression, inferring that it might act through a different mechanism. Molecular docking is used to give insights on the ability of isolated compounds to bind with different active sites in mTOR. Collectively, the integrated phytochemical, in silico, and molecular biology approach reveal that V. minor and its metabolite could be repurposed for the management of dermatological disorders where these markers are dysregulated, which opens the gate to develop new therapeutics in the future.

Evaluation of antimicrobial, antiquorum sensing, and cytotoxic activities of new vanillin 1,2,3-triazole derivatives.

Vanillin (1), the main constituent of vanilla species, was used as a starting natural scaffold for the synthesis of five new (2-6) and one known (7) triazole derivatives via click chemistry using the copper (I)-catalyzed azide-alkyne cycloaddition method. Vanillin and its new derivatives; 4-{1-[2-Hydroxymethyl-5-(5 methyl-2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-tetrahydro-furan-3-yl]-1H[1,2,3]triazol-4-ylmethoxy}-3-methoxy-benzaldehyde (2); [4-(4-Formyl-2methoxy-phenoxymethyl)-[1,2,3]triazol-1-yl]-acetic acid methyl ester (3); 4-[1-(4-Acetyl-phenyl)-1H-[1,2,3]triazol-4-ylmethoxy]-3-methoxy-benzaldehyde (4); 4-[4-(1-Benzyl-1H-[1,2,3]triazol-4-ylmethoxy)-3-methoxy-phenyl]-but-3-en-2-one (5); and 4-[4-(1-Benzyl-1H-[1,2,3]triazol-4-ylmethoxy)-3-methoxy-phenyl]-4-hydroxy-butan-2-one (6), as well as the previously known derivative (7) were subjected to antimicrobial, antiquorum-sensing and cytotoxic evaluation. Compounds 4-7 possessed the most notable enhancement in the anti-bacterial activity against Bacillus cereus, Pseudomonas aeruginosa and antifungal activity against Candida albicans. However, compounds 1 and 2 exhibited high antiquorum-sensing activity against Chromobacterium violaceum using catechin as a positive control. Compounds 4-7 demonstrated selective cytotoxicity against MCF-7 and HepG2 cancer cells compared to normal lung fibroblast cells (WI-38). These findings proved the usefulness of synthesis bioactive derivatives from vanillin through chemical modifications.

Down regulation of fatty acid synthase via inhibition of PI3K/AKT/mTOR in ovarian cancer cell line by novel organoselenium pseudopeptide.

Ovarian cancer (OC) is the 7th most common cancer in women world-wide and the 3rd most common female cancer. For the treatment of OC, there is no successful therapeutic. The medications that are currently available have significant side effects and a low therapeutic index. This work aimed to evaluate the anticancer activity of organoselenium pseudopeptide compound against OC cell lines. After treatment with 50 â€‹µM of compound 4 (CPD 4), the viability was determined. The anticancer activity was further investigated by different methods including cell cycle and apoptosis analysis, colony formation assay, zymography, comet assay and Western blot. In comparison to a positive control, compound 4 showed cytotoxicity toward A2780CP cells rather than A2780 and SKOV-3 â€‹cells. Compound 4 was more selective to OC cells rather than HSF cells. Moreover, Compound 4 was able to inhibit cell migration and proliferation. The anticancer effect of compound 4 was found to be partially via cell cycle arrest, overexpression of p27 â€‹cell cycle inhibitor and induction of apoptosis through DNA fragmentation and activated production of ROS. Compound 4 had a differential effect on the modulation of PI3K/AKT/mTOR signaling pathway in the OC treated cell lines, also inhibited lipogenesis process via downregulation of FASN expression. Conclusion: This work highlights the unique role of Compound 4 against OC via modulation of oxidative stress, inhibition of survival PI3K/AKT/mTOR pathway. Compound 4 was found to be a promising alternative therapy for the treatment of OC in this investigation.

Novel spirooxindole based benzimidazole scaffold: In vitro, nanoformulation and in vivo studies on anticancer and antimetastatic activity of breast adenocarcinoma.

The present work provided in vitro anticancer investigation of novel spirooxindole based benzimidazole scaffold SP1 and its nanoformulation with in vivo evaluation of anticancer and antimetastatic activity as potential drug for breast adenocarcinoma. The synthesized compound SP1 exhibited potent growth inhibitory efficacy against four types of human cancer (breast, prostate, colon and lung) cell lines with IC50 = 2.4, 3.4, 7.24 and 7.81 µM and selectivity index 5.79, 4.08, 1.93 and 1.78 respectively. Flow cytometric analysis illustrated that SP1 exhibited high apoptotic effect on all tested cancer cell lines (38.22-52.3 %). The mode of action of this promising compound was declared by its ability to upregulate the gene expression of p21 (2.29-3.91 folds) with suppressing cyclin D (1.9-8.93 folds) and NF-κB (1.26-1.44 fold) in the treated cancer cells. Also, it enhanced the protein expression of apoptotic marker p53 and moderate binding affinity for MDM2 (KD;7.94 µM). Notwithstanding these promising impressive findings, its selectivity against cancer cell lines and safety on normal cells were improved by nanoformulation. Therefore, SP1 was formulated as ultra-flexible niosomal nanovesicles (transethoniosomes). The ultra-deformability is attributable to the synergism between ethanol and edge activators in improving the flexibility of the nanovesicular membrane. F8 exhibited high deformability index (DI) of (23.48 ± 1.4). It was found that % SP1 released from the optimized transethoniosomal formula (F8) after 12 h (Q12h) was 84.17 ± 1.29 % and its entrapment efficiency (%EE) was 76.48 ± 1.44 %. Based upon the very encouraging and promising in vitro results, an in vivo study was carried out in female Balb/c mice weighing (15-25 g). SP1 did halt the proliferation of breast cancer cells as well as suppressed the metastasis in other organs like liver, lung and heart.

Development of Cyclodextrin-Functionalized Transethoniosomes of 6-Gingerol: Statistical Optimization, In Vitro Characterization and Assessment of Cytotoxic and Anti-Inflammatory Effects.

The poor solubility and stability of 6-gingerol (6-G) could hamper its clinical applications. The aim of the current study was to develop a novel ultra-deformable cyclodextrin-functionalized transethoniosomes (CD-TENs) as a promising delivery system for 6-G. Transethoniosomes (TENs) are flexible niosomes (NVs) due to their content of ethanol and edge activators (EAs). CD-functionalized nanoparticles could improve drug solubility and stability compared to the corresponding nanovesicles. 6-G-loaded ethoniosomes (ENs) were formulated by the ethanol injection technique in the presence and absence of EA and CD to explore the impact of the studied independent variables on entrapment efficiency (EE%) and % 6-G released after 24 h (Q24h). According to the desirability criteria, F8 (CD-functionalized transethoniosomal formula) was selected as the optimized formulation. F8 demonstrated higher EE%, permeation, deformability and stability than the corresponding TENs, ENs and NVs. Additionally, F8 showed higher cytotoxic and anti-inflammatory activity than pure 6-G. The synergism between complexation with CD and novel ultra-deformable nanovesicles (TENs) in the form of CD-TENs can be a promising drug delivery carrier for 6-G.

Natural inspired piperine-based ureas and amides as novel antitumor agents towards breast cancer.

In this work, the natural piperine moiety was utilised to develop two sets of piperine-based amides (5a-i) and ureas (8a-y) as potential anticancer agents. The anticancer action was assessed against triple negative breast cancer (TNBC) MDA-MB-231, ovarian A2780CP and hepatocellular HepG2 cancer cell lines. In particular, 8q stood out as the most potent anti-proliferative analogue against TNBC MDA-MB-231 cells with IC50 equals 18.7 µM, which is better than that of piperine (IC50 = 47.8 µM) and 5-FU (IC50 = 38.5 µM). Furthermore, 8q was investigated for its possible mechanism of action in MDA-MB-231 cells via Annexin V-FITC apoptosis assay and cell cycle analysis. Moreover, an in-silico analysis has proposed VEGFR-2 as a probable enzymatic target for piperine-based derivatives, and then has explored the binding interactions within VEGFR-2 active site (PDB:4ASD). Finally, an in vitro VEGFR-2 inhibition assay was performed to validate the in silico findings, where 8q showed good VEGFR-2 inhibitory activity with IC50 = 231 nM.

Effect of polycaprolactone nanofibers loaded with oxytetracycline hydrochloride and zinc oxide as an adjunct to SRP on GCF lipocalin-2 levels in periodontitis patients: A clinical and laboratory study.

Background. The aim of this study was the clinical and laboratory evaluation of using polycaprolactone (PCL) nanofibers loaded with oxytetracycline hydrochloride (OTC) and zinc oxide (ZnO) as an adjunct to mechanical therapy in managing stage II grade A periodontitis patients concerning GCF lipocalin2- levels. Methods. Fifty stage II grade A periodontitis patients (27 women and 23 men, with an age range of 30‒60) were enrolled in the study. The patients were randomly assigned to five equal groups and treated with scaling and root planing (SRP), followed by local application of PCL nanofibers: group I: SRP + PCL loaded with OTC and ZnO, group II: SRP + PCL loaded with OTC, group III: SRP + PCL loaded with ZnO, group IV: SRP + unloaded PCL, and group V: SRP alone. Additionally, 10 healthy subjects with healthy periodontium (group VI) (age- and gender-matched) served as the negative control. Nanofibers were applied in the selected pockets of periodontitis patients in groups I to IV once weekly for two months. All the participants were examined clinically by assessing periodontal indices (gingival index, plaque index, pocket depth, and clinical attachment level), and biochemically by assessing GCF lipocalin-2 levels. Results. Compared to controls, periodontitis groups (I, II, III, IV, and V) showed significant elevation of both clinical parameters and GCF lipocalin2- levels at baseline. In addition, these parameters improved significantly after treatment, which was more pronounced in groups I, II-, and III) compared to groups IV and V. However, it did not reach normal values. Conclusion. In association with SRP, PCL nanofibers loaded with OTC and ZnO had beneficial therapeutic effects at both clinical and laboratory levels.

Construction of Spirooxindole Analogues Engrafted with Indole and Pyrazole Scaffolds as Acetylcholinesterase Inhibitors.

Twenty-five new hits of spirooxindole analogs 8a-y engrafted with indole and pyrazole scaffolds were designed and constructed via a [3+2]cycloaddition (32CA) reaction starting from three components: new chalcone-based indole and pyrazole scaffolds 5a-d, substituted isatins 6a-c, and secondary amines 7a-d. The potency of the compounds were assessed in modulating cholinesterase (AChE) activity using Ellman's method. Compounds 8i and 8y showed the strongest acetylcholine esterase inhibition (AChEI) with IC50 values of 24.1 and 27.8 µM, respectively. Molecular docking was used to study their interaction with the active site of hAChE.

Natural inspired piperine-based sulfonamides and carboxylic acids as carbonic anhydrase inhibitors: Design, synthesis and biological evaluation.

The natural product piperine, the major bioactive alkaloid present in black pepper fruits, has the ability to modulate the functional activity of several biological targets. In this study, we have utilized the natural piperine as a tail moiety to develop new SLC-0111 analogues (6a-d, 8 and 9) as potential carbonic anhydrase inhibitors. Thereafter, different functionalities, free carboxylic acid (11a-c), acetyl (13a) and ethyl ester (13b-c), were exploited as bioisosteres of the sulfamoyl functionality. All piperine-based derivatives were assessed for their inhibitory actions against four human (h) CA isoforms: hCA I, II, IX and XII. The best hCA inhibitory activity was observed for the synthesized primary piperine-sulfonamides (6a-d and 8). In particular, both para-regioisomers (6c and 8) emerged as the most potent hCA inhibitors in this study with two-digit nanomolar activity against hCA II (KIs = 93.4 and 88.6 nM, respectively), hCA IX (KIs = 38.7 and 68.2 nM, respectively), and hCA XII (KIs = 57.5 and 45.6 nM, respectively). Moreover, piperine-sulfonamide 6c was examined for its anti-cancer and pro-apoptotic actions towards breast MCF-7 cancer cell line. Collectively, piperine-based sulfonamides could be considered as a promising scaffold for development of efficient anticancer candidates with potent CA inhibitory activities.

Anticancer activity of new cationic arylthiophenes against hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is the second most common cancer-related death in the world. No effective curative option exists for the treatment of HCC. The available drugs exhibit severe toxic effects and low therapeutic index. AIM: This work aimed to examine different monocationic arylthiophene derivatives for possible use as chemotherapeutic agents against HCC. METHODS: The IC50 values for the compounds were determined. The mechanism of cytotoxicity was further investigated using different methods. RESULTS: Compound 2j proved to retain the highest cytotoxicity in comparison to as a positive control. The selectivity index of compound 2j revealed the safety to normal cells. Moreover, compound 2j was able to inhibit HepG2 cells´ migration and division. The anticancer effect of compound 2j was found to be partially via cell cycle arrest, activation of the tumour suppressor p53 protein, and induction of apoptosis via both intrinsic and extrinsic pathways. Compound 2j has a potential sensitization activity and significantly reduced the IC50 values for the anticancer drugs doxorubicin, cisplatin, and taxol. CONCLUSION: The tested arylthiophenes showed a potent cytotoxicity against HepG2 cells and were safe to normal cells. The most active compound 2j was found to be able to inhibit cell division and migration and also to induce apoptosis. Compound 2j also proved to have a sensitization effect on standard anticancer drugs.

Sterols and Triterpenes from Dobera glabra Growing in Saudi Arabia and Their Cytotoxic Activity.

A new lupane caffeoyl ester, lup-20(29)-ene 3ß-caffeate-30-al (7), and a new oleanane-type triterpene, 3ß-hydroxyolean-13(18)-en-12-one (17), were isolated from the aerial parts of Dobera glabra (Forssk), along with ten known triterpenes, including seven lupane-type lupeol (1), 30-nor-lup-3ß-ol-20-one (2), ∆1-lupenone (3), lup-20(29)-en-3ß,30-diol (4), lupeol caffeate (5), 30-hydroxy lup-20(29)-ene 3ß-caffeate (6), and betunaldehyde (8); three oleanane-type compounds were also identified, comprising δ-amyrone (15), δ-amyrin (16), and 11-oxo-ß-amyrin (18); together with six sterols, comprising ß-sitosterol (9), stigmasterol (10), 7α-hydroxy-ß-sitosterol (11), 7α-hydroxy-stigmasterol (12), 7-keto-ß-sitosterol (13), and 7-keto-stigmasterol (14). Their structures were elucidated using a variety of spectroscopic techniques, including 1D (1H, 13C, and DEPT-135 13C) and 2D (1H-1H COSY, 1H-13C HSQC, and 1H-13C HMBC) nuclear magnetic resonance (NMR) and accurate mass spectroscopy. Subsequently, the different plant extracts and some of the isolated compounds (1-9, 11 and 13) were investigated for their possible cytotoxic activity in comparison to cisplatin against a wide array of aggressive cancer cell lines, such as colorectal cancer (HCT-116), hepatocellular carcinoma (HepG-2), and prostate cancer (PC-3) cell lines. Compound 11 displayed broad cytotoxicity against all of the tested cell lines (IC50 ≅ 8 µg/mL in all cases), and a high safety margin against normal Vero cells (IC50 = 70 µg/mL), suggesting that 11 may be a highly selective and effective anticancer agent candidate. Notably, the evidence indicated that the mode of action of compound 11 could possibly consist of the inhibition of phosphodiesterase I (80.2% enzyme inhibition observed at 2 µM compound concentration).

Effect of phenolic compounds from the leaves of Psidium guajava on the activity of three metabolism-related enzymes.

Enzyme activity modulation by synthetic compounds provide strategies combining the inhibitory and therapeutic mode of action of the confirmed inhibitors. However, natural modulators could offer a valuable alternative for synthetic ones for the treatment of different chronic diseases (diabetes, hypertension, cancer); due to the numerous side effects of the latter. In vitro screening assays were conducted for Psidium guajava leaf methanolic extract against three metabolism-related enzymes; α-amylase, tyrosinase, and hyaluronidase. The obtained results showed that the examined extract retained weak and moderate multitarget inhibition against α-amylase, tyrosinase, and hyaluronidase, respectively; however, the leaf fractions exhibited stronger inhibitions for the three investigated enzymes. Fractionation of P. guajava leaf extract revealed that anthraquinones and ellagic acid are of the major active compounds with inhibitory activities for α-amylase, tyrosinase, and hyaluronidase. Kinetic studies showed that quinalizarin inhibition is competitive for both α-amylase and hyaluronidase, and ellagic acid inhibition for tyrosinase and hyaluronidase is competitive and un-competitive, respectively. The molecular docking studies of quinalizarin and ellagic acid with α-amylase, tyrosinase, and hyaluronidase showed high binding energies with different bonds stabilizing the ligand-protein complex. Compiling all obtained results led to conclude that both P. guajava leaf fractions, quinalizarin and ellagic acid, have multitarget activities with potential therapeutic applications in many metabolic disorders.

Synthesis of new selective cytotoxic ricinine analogues against oral squamous cell carcinoma.

Sixteen new analogues were synthesized from ricinine and tested alongside with seven known analogues for their cytotoxic activity against oral cancer (SAS cells) and normal epithelial cells (L132 cells). In contrast to 5-FU, the synthesized ricinine analogues did not show toxicity to normal cells. However, some of them inhibited the proliferation of oral cancer cells at 25 µM as evident from the MTT assay results. Ricinine analogue (19) was shown to be the most active derivative (69.22% inhibition). Potential targets involved in the oral cancer inhibitory activity of compound 19 were investigated using in-silico studies and western blot analysis. PTP1B was predicted to be a target for ricinine using reverse docking approach. This prediction was confirmed by western blot analysis that revealed the downregulation of PTP1B protein by compound 19. Moreover, it showed downregulation of COX-2 which is also extensively expressed in oral cancer.