Phytochemical investigation and anti-inflammatory potential of Atriplex leucoclada Boiss.

BACKGROUND: The plant kingdom has long been considered a valuable source for therapeutic agents, however, some plant species still untapped and need to be phytochemically and biologically explored. Although several Atriplex species have been investigated in depth, A. leucoclada, a halophytic plant native to Saudi Arabian desert, remains to be explored for its phytochemical content and biological potentials. Herein, the current study investigated the metabolic content and the anti-inflammatory potential of A. leucoclada. METHODS: Powdered aerial parts of the plant were defatted with n-hexane then the defatted powder was extracted with 80% methanol. n-Hexane extract (ATH) was analyzed using GC-MS, while the defatted extract (ATD) was subjected to different chromatographic methods to isolate the major phytoconstituents. The structures of the purified compounds were elucidated using different spectroscopic methods including advanced NMR techniques. Anti-inflammatory activity of both extracts against COX-1 and COX-2 enzymes were examined in vitro. Molecular docking of the identified compounds into the active sites of COX-1 and COX-2 enzymes was conducted using pdb entries 6Y3C and 5IKV, respectively. RESULTS: Phytochemical investigation of ATD extract led to purification and identification of nine compounds. Interestingly, all the compounds, except for 20-hydroxy ecdysone (1), are reported for the first time from A. leucoclada, also luteolin (6) and pallidol (8) are isolated for the first time from genus Atriplex. Inhibitory activity of ATD and ATH extracts against COX-1 and COX-2 enzymes revealed concentration dependent activity of both fractions with IC50 41.22, 14.40 µg/ml for ATD and 16.74 and 5.96 µg/ml for ATH against COX-1 and COX-2, respectively. Both extracts displayed selectivity indices of 2.86 and 2.80, respectively as compared to 2.56 for Ibuprofen indicating a promising selectivity towards COX-2. Molecular docking study supported in vitro testing results, where purified metabolites showed binding affinity scores ranged from -9 to -6.4 and -8.5 to -6.6 kcal/mol for COX-1 and 2, respectively, in addition the binding energies of GC-MS detected compounds ranged from -8.9 to -5.5 and -8.3 to -5.1 kcal/mol for COX-1 and 2, respectively as compared to Ibuprofen (-6.9 and -7.5 kcal/mol, respectively), indicating high binding affinities of most of the compounds. Analysis of the binding orientations revealed variable binding patterns depending on the nature of the compounds. Our study suggested A. leucoclada as a generous source for anti-inflammatory agents.

Multi-target action of Garcinia livingstonei extract and secondary metabolites against fatty acid synthase, α-glucosidase, and xanthine oxidase.

Garcinia livingstonei is a traditional herbal medicine that showed beneficial health effects and bioactivities. Four compounds have been isolated from the plant leaves and were elucidated as lupeol, betulin, podocarpusflavone A, and amentoflavone. The inhibitory activities of G. livingstonei extract and isolated metabolites against fatty acid synthase (FAS), α-glucosidase, and xanthine oxidase (XO) were investigated in vitro. The affinity of the compounds toward the studied enzymes was investigated in silico. The plant extract inhibited FAS, α-glucosidase, and XO with IC50 values of 26.34, 67.88, and 33.05 µg/mL, respectively. Among the isolated metabolites, betulin exhibited the most inhibitory activity against α-glucosidase and XO with IC50 values of 38.96 and 30.94 µg/mL, respectively. Podocarpusflavone A and betulin were the most potent inhibitors of FAS with IC50 values of 24.08 and 27.96 µg/mL, respectively. Computational studies corroborated these results highlighting the interactions between metabolites and the enzymes. In conclusion, G. livingstonei and its constituents possess the potential to modulate enzymes involved in metabolism and oxidative stress.

Promising Cytotoxic butenolides from the Soybean endophytic fungus Aspergillus terreus: a combined molecular docking and in-vitro studies.

AIM: This study aimed to use one strain many compounds approach (OSMAC) to investigate the cytotoxic potential of Aspergillus terreus associated with soybean versus several cancer cell lines, by means of in-silico and in vitro approaches. METHODS AND RESULTS: Fermentation of the isolated strain was done on five media. The derived extracts were investigated for their inhibitory activities against three human cancer cell lines; mammary gland breast cancer (MCF-7), colorectal adenocarcinoma (Caco-2), and hepatocellular carcinoma (HepG2) using MTT Assay. The fungal mycelia fermented in Modified Potato Dextrose Broth (MPDB) was the most cytotoxic extract against HepG2, MCF-7, and Caco-2 cell lines with IC50 4.2 ± 0.13, 5.9 ± 0.013 and 7.3 ± 0.004 µg mL-1, respectively. MPDB extract was scaled up resulting in the isolation of six metabolites; three fatty acids (1, 2, and 4), one sterol (3) and two butenolides (5 and 6) by column chromatography. The isolated compounds (1-6) were screened through a molecular docking approach for their binding aptitude to various active sites. butyrolactone-I (5) revealed a significant interaction within the CDK2 active site, while aspulvinone E (6) showed promising binding affinity to FLT3 and EGFR active sites that was confirmed by in vitro CDK2, FLT3 and EGFR inhibitory activity. Finally, the in vitro cytotoxic activities of butyrolactone-I (5) and aspulvinone E (6) revealed the antiproliferative activity of butyrolactone-I (5), against HepG2 cell line (IC50 = 17.85 ± 0.32 µM). CONCLUSION: Molecular docking analysis and in vitro assays suggested the CDK2/A2 inhibitory potential of butyrolactone-I (5) in addition to the promising interaction abilities of aspulvinone E (6) with EGFR and FLT3 active sites as a possible mechanism of their biological activities.

Four new phenolics and antiparasitic secondary metabolites from Flacourtia rukam Zoll. & Mortizi.

Phytochemical investigation of Flacourtia rukam Zoll. & Mortizi (F. rukam) leaves and bark led to the isolation and characterization of seventeen compounds of which four phenolics were not previously described; 2-[(benzoyloxy)methyl]-phenyl-O-ß-xylosyl-(1→2)-ß-glucopyranoside (1), 2-[(benzoyloxy)methyl]-4-hydroxyphenyl-O-ß-xylosyl-(1→2)-ß-D-glucopyranoside (2), 2-hydroxy-5-(2-hydroxyphenoxy)phenoxy-ß-glucopyranoside (3) and biphenyl-1,1',2,2'-tetraol (5). Interestingly, the later compound is known as a synthetic but this is the first report for its isolation from nature. Chemical structures were established using extensive analysis of spectroscopic data (1 D and 2 D NMR and HRESIMS). Biphenyl-1,1,2,2'-tetrol (5) exhibited a good activity against Trypanosoma brucei trypomastigotes with IC50= 6.66 ug/mL. Compounds 2, 5, 9, 10, 11 and 12 showed a good in-vitro anti-inflammatory activity using proteinase inhibitory assay. On the contrary, all tested compounds were inactive as antileishmanial or antimalarial.

Salicylic acid increases flavonolignans accumulation in the fruits of hydroponically cultured Silybum marianum.

Silybum marianum (L.) Gaertn. (Asteraceae) was hydroponically cultured using a nutrient film technique system. Silibinin, isosilibinin and silychristin were detected in the fruits of the cultured plants. The effect of salicylic acid on the improvement of flavonolignans production by the fruits of the hydroponically cultured S. marianum was investigated. Salicylic acid was added to the nutrient solution at different concentrations (100, 200 and 400 µM) and the mature fruits of the plant were collected five days after elicitor addition. The fruits were then analyzed for their total flavonolignans contents and individual components using quantitative proton nuclear magnetic resonance spectroscopy (qHNMR) and high-performance liquid chromatography (HPLC). The results showed that elicitation with salicylic acid at 200 µM for five days increased production of total flavonolignans (1.7-fold by qHNMR and 1.6-fold by HPLC) higher than the control cultures and (1.4-fold by qHNMR and 1.1-fold by HPLC) higher than the cultivated plants. Silychristin was the major flavonolignan produced by the cultured plant. Elicitation by 200 µM salicylic acid increased silychristin production (1.6-fold by qHNMR and HPLC) higher than the control cultures and (1.3-fold by qHNMR and 1.0-fold by HPLC) higher than the cultivated plants. The present study provides a chance to improve secondary metabolite yield, serves as a useful tool for studying the biosynthesis of these medicinally valuable compounds and its regulation in plant and spots more light on hydroponic system as an important agricultural technique.

Natural product diversity from the endophytic fungi of the genus Aspergillus.

The endophytic fungus Aspergillus is considered as an enormous source of chemical leads with promising biological activities. Different Aspergillus species have proved their ability to produce plenty of secondary metabolites including butenolides, alkaloids, terpenoids, cytochalasins, phenalenones, ρ-terphenyls, xanthones, sterols, diphenyl ether and anthraquinone derivatives with diverse biological activities, such as anti-cancer, antifungal, anti-bacterial, anti-viral, anti-inflammatory, antitrypanosomal and antileishmanial activities. From January 2015 until December 2019, three hundred and sixty-one secondary metabolites were reported from different endophytic Aspergillus species. This review discusses the isolated secondary metabolites from different endophytic Aspergillus species reported from January 2015 to December 2019 along with their reported biological activities and structural aspects whenever applicable.

Cytotoxic, hepatoprotective and antioxidant activities of Silybum marianum variety albiflorum growing in Egypt.

Silymarin prepared from the fruits of Silybum marianum (L.) Gaertn. (Asteraceae) has long been used for the treatment of liver disorders. This study was carried out to evaluate the protective effect of the fruit extract of white-flowered S. marianum variety albiflorum Eig. (WSE) against paracetamol-induced liver toxicity in rats. Silyhermin, isosilandrins A/B were identified as the major flavonolignans in WSE. Cytotoxic activities of WSE and isolated flavonolignans compared to silymarin were carried out using sulforhodamine B assay. WSE, silyhermin and isosilandrins had no obvious harmful effect on normal human cell line compared to silymarin with IC50 values 78.95, 84.34, 72.14 and 16.83 µg/ml, respectively. The hepatoprotective activity of WSE at dose 50 mg/kg was comparable to silymarin (100 mg/kg). These data were supplemented with histopathological studies on liver sections. The hepatoprotective effects of WSE on oxidative stress induced by administration of paracetamol are probably associated with its antioxidant properties.

Linear regression analysis of silychristin A, silybin A and silybin B contents in Silybum marianum.

Quantitative correlations between the contents of the flavonolignans silychristin A and silybins A/B provide biosynthetic clues that support a pathway in which one mesomeric form of a taxifolin radical is undergoing an oxidative coupling with a coniferyl alcohol radical. The flavonolignan content and patterns reported in the literature for 53 samples, representing populations of the Silybum marianum plant growing in different parts of the world, were subject to a meta-analysis. Linear regression analyses were carried out on these data sets, and a mathematical model was derived that predicts the content of silychristin A relative to the metabolomic pattern of its congeners. The validity of the model was verified by applying it to test samples. This approach could potentially become a tool to enhance the understanding of both the relative composition of the silymarin complex and the biosynthetic pathways that underlie its formation.

Chemotaxonomic and biosynthetic relationships between flavonolignans produced by Silybum marianum populations.

Flavonolignans constitute an important class of plant secondary metabolites formed by oxidative coupling of one flavonoid and one phenylpropanoid moiety. The standardized flavonolignan-rich extract prepared from the fruits of Silybum marianum is known as silymarin and has long been used medicinally, prominently as an antihepatotoxic and as a chemopreventive agent. Principal component analysis of the variation in flavonolignan content in S. marianum samples collected from different locations in Egypt revealed biosynthetic relationships between the flavonolignans. Silybin A, silybin B, and silychristin are positively correlated as are silydianin, isosilychristin, and isosilybin B. The detection of silyamandin in the extracts of S. marianum correlates with isosilychristin and silydianin content. The positive correlation between silydianin, isosilychristin, and silyamandin was demonstrated using quantitative 1H nuclear magnetic resonance spectroscopy (qHNMR). These correlations can be interpreted as evidence for the involvement of a flavonoid radical in the biosynthesis of the flavonolignans in S. marianum. The predominance of silybins A & B over isosilybin A & B in the silybin-rich samples is discussed in light of the relative stabilities of their respective radical flavonoid biosynthetic intermediates.