New cytotoxic spatane diterpenoids from marine alga Stoechospermum marginatum.

Three new spatane diterpenoids (1-3) were isolated from the brown alga Stoechospermum marginatum together with three known compounds (4-6). The structures of these compounds were determined by the detailed NMR spectroscopic and Mass spectrometric analyses. All the isolated compounds were screened for their cytotoxic potentials against a panel of four human cancer cell lines, which include DU145 (Prostate), B16F10 (Melanoma), MDA MB-231 (Breast), and HeLa (Cervical) along with a normal cell line (HEK). The screening results indicated that compounds 1, 4 and 5 displayed significant activities against B16F10 [IC50, 6.21 ± 0.14, 5.88 ± 0.21, 5.31 ± 0.24 µM] and MDA MB-231 [9.25 ± 0.61, 4.59 ± 0.14, 4.19 ± 0.13 µM] cell lines, respectively. In view of their significant activity, these compounds 1, 4 and 5 were further taken up for detailed fluorescence assays, scratch assay and flow cytometry analysis, which revealed that they diminished proliferation and arrested cell cycle in the S phase and G2/M phase, which induced cell death by apoptosis. Overall, based on their considerable results, these compounds could serve as lead molecules in the development of anticancer drug candidates.

Comprehensive Lichenometabolomic Exploration of Ramalina conduplicans Vain Using UPLC-Q-ToF-MS/MS: An Identification of Free Radical Scavenging and Anti-Hyperglycemic Constituents.

In this study, we propose ultra-performance liquid chromatography coupled with quadrupole/time-of-flight mass spectrometry (UPLC-QToF-MS/MS)-guided metabolite isolation as a choice analytical approach to the ongoing structure−activity investigations of chemical isolates from the edible lichen, Ramalina conduplicans Vain. This strategy led to the isolation and identification of a new depside (5) along with 13 known compounds (1−4, 6−14), most of which being newly described in this lichen species. The structures of the isolates were established by detailed analysis of their spectral data (IR, NMR, and Mass). The acetone extract was further analyzed by UPLC-Q-ToF-MS/MS in a negative ionization mode, which facilitated the identification and confirmation of 18 compounds based on their fragmentation patterns. The antioxidant capacities of the lichen acetone extract (AE) and isolates were measured by tracking DPPH and ABTS free radical scavenging activities. Most isolates displayed marked radical scavenging activities against ABTS while moderate activities were observed against DPPH radical scavenging. Except for atranol (14), oxidative DNA damage was limited by all the tested compounds, with a marked protection for the novel isolated compound (5), as previously noted for the acetone extract (p < 0.001). Furthermore, compound (4) and acetone extract (AE) have inhibited intestinal α-glucosidase enzyme significantly (p < 0.01). Although some phytochemical studies were already performed on this lichen, this study provided new insights into the isolation and identification of bioactive compounds, illustrating interest in future novel analytical techniques.

Facet-Dependent Bactericidal Activity of Ag3PO4 Nanostructures against Gram-Positive/Negative Bacteria.

Ag3PO4 nanostructures (APNs) containing silver (Ag metal; of the noble metal families) have the potential to exhibit enzyme-mimetic activity. A nanostructure shape, including its surface facets, can improve the bioactivity of enzyme mimicry, yet the molecular mechanisms remain unclear. Herein, we report facet-dependent peroxidase and oxidase-like activity of APNs with both antibacterial and biofilm degrading properties through the generation of reactive oxygen species. Cubic APNs had superior antibacterial effects than rhombic dodecahedral shapes when inhibiting Gram-positive and Gram-negative bacterial pathogen proliferation and biofilm degradation. A similar performance was observed for rhombic dodecahedral shapes, being greater than tetrahedral-shaped APNs. The extent of enzyme-mimetic activity is attributed to the facets {100} present in cubic APNs that led the peroxide radicals to inhibit the proliferation of bacteria and degrade biofilm. These facets were compared to rhombic dodecahedral APNs {110} and tetrahedral APNs {111}, respectively, to reveal a facet-dependent enhanced antibacterial activity, providing a plausible mechanism for shape-dependent APNs material enzyme-mimetic effects on bacteria. Thus, our research findings can provide a direction to optimize bactericidal materials using APNs in clinically relevant applications.

Bombax ceiba calyx displays antihyperglycemic activity via improving insulin secretion and sensitivity: Identification of bioactive phytometabolomes by UPLC-QTof-MS/MS.

Vegetables are considered good food for the management of hyperglycemia. Bombax ceiba L. (family: Bombacaceae) calyces are part of traditional vegetables. This study evaluated its usefulness on various parameters responsible for the development of hyperglycemia and conducted phytometabolomic analysis to identify phytochemicals responsible for the observed activities. It was found that the aqueous methanol extract of its calyces (B. ceiba calyx extract, BCE) reduced (12.4%) significantly (p < 0.05) the development of sucrose-induced postprandial hyperglycemic load in rats. In-vitro studies revealed that BCE improved glucose-stimulated insulin secretory activity in MIN6 cells plausibly by decreasing ADP/ATP ratio. BCE also augmented concentration-dependent (5 µg, 10 µg, and 20 µg) increase in glucose uptake in hyperglycemic L6 myotubes both by non-insulin-dependent manner (35%, 68%, and 132%, respectively) and insulin-dependent manner (42%, 59%, and 172%, respectively). The insulin-stimulated GLUT4 translocation was compromised (34%) significantly (p < 0.05) under hyperglycemic condition; however, it was improved by 23% and 72% (p < 0.001) when L6 myotubes were primed with 10 and 20 µg of BCE, respectively. Hyperglycemia aggravated reactive oxygen species (ROS) generation in L6 myotubes. The ROS generation was significantly (p < 0.001) reduced by priming myotubes with BCE before challenging myotubes to hyperglycemic environment, possibly by preserving cellular antioxidant enzymes catalase, glutathione peroxidase, and reduced glutathione levels. Phytometabolomic analysis disclosed a number of phytochemicals present in B. ceiba calyces known to display these activities. This is the first study reporting antihyperglycemic activity in B. ceiba calyces, its mechanisms of action, and phytometabolomic profile applying UPLC-QTof-MS/MS technique. PRACTICAL APPLICATION: B. ceiba calyces are part of traditional vegetables. Our study finds that B. ceiba calyces contain phytochemicals possessing antihyperglycemic, insulin secretory, insulin sensitization properties, and potentials for preserving hyperglycemia-induced vitiations in cellular antioxidant defense. These observations provide foundation for exploring further possibilities of B. ceiba calyces to become valuable dietary inclusion in the diet of people suffering from metabolic disorders.

Phytometabolomic analysis of boiled rhizome of Nymphaea nouchali (Burm. f.) using UPLC-Q-TOF-MSE, LC-QqQ-MS & GC-MS and evaluation of antihyperglycemic and antioxidant activities.

Phytometabolomic analysis of Nymphaea nouchali (Burm. F.) boiled rhizome was carried out utilizing UPLC-Q-TOF-MSE, LC-QqQ-MS and GC-MS techniques and evaluated for antihyperglycemic and antioxidative stress potentials. Metabolomic analysis revealed presence of multiple antidiabetic and antioxidant compounds. Boiled rhizome powder exhibited potent antihyperglycemic activity against sugar-induced postprandial hyperglycemia in rats plausibly due to the presence of intestinal α-glucosidase inhibitory and augmenting cellular glucose uptake activities. It also prevented hyperglycemia-induced hemoglobin and insulin glycation. Rhizome displayed potent reducing power, effectively scavenged various reactive oxygen species. It displayed antioxidative stress potential in assuaging H2O2 induced erythrocyte hemolysis and antioxidant activity by inhibiting membrane lipid peroxidation. Boiled rhizome was also found to preserve the loss of cellular antioxidants under H2O2 induced oxidative stress and disturbances caused to mitochondrial membrane potential. This is the first research reporting boiled N. nouchali rhizome as an ideal food material to manage the cause of hyperglycemia and resultant oxidative stress.

"Click" reaction based synthesis of nimbolide derivatives and study of their insect antifeedant activity against Spodoptera litura Larvae.

A series of Nimbolide-triazole conjugates were synthesized through copper(I)- catalyzed azide-alkyne "click" chemistry approach and these derivatives (2-4, 2a-2l) were characterized using modern spectroscopic techniques. Antifeedant activities of these derivatives were studied on Tobacco Caterpillar, Spodoptera litura (F.) using no-choice leaf disk bioassay. Interestingly, the synthesized derivatives were more effective in reducing feedancy by insect species when compared to the parent nimbolide. Among the tested compounds, 2a, 2c, and 2d showed potent antifeedancy with ED50 values of 0.49, 0.95 and 0.97mg/cm2 against S. litura. Several of the analogs were also toxic or caused developmental abnormalities following leaf disc assay.

Anti-cancer evaluation of carboxamides of furano-sesquiterpene carboxylic acids from the soft coral Sinularia kavarattiensis.

The chemical investigation of soft coral Sinularia kavarattiensis is described. It yielded furano-sesquiterpene carboxylic acids 1 and 2 and their methyl esters 3 and 4. Semi-synthesis of furano-sesquiterpene carboxylic acid 1 gave amide derivatives 5-12. Structures of all the compounds were established by IR, NMR and mass spectral analysis. Interestingly all compounds are selectively potent on leukemia cell line. All these compounds were screened for cytotoxic activity against five human cancer cell lines (leukemia, prostate, lung, breast and cervix). Among these compounds 9 and 10 showed promising activity against leukemia and prostate cancer cell lines.

Hemisynthesis of selected embelin analogs and investigation of their proapoptotic activity against cancer cells.

Embelin is a natural product, inhibitor of XIAP (X-chromosome-linked Inhibitor of APoptosis) with strong proapoptotic properties on cancer cells. In order to clarify the role of two OH groups on benzoquinone core, we have prepared by hemisynthesis close analogs of embelin, where these OH groups have been replaced in a systematic manner by OMe and OAc groups. Proapoptotic activities of six embelin derivatives have been studied as single agent, or in combination with TRAIL, and their abilities to interact with XIAP have been evaluated by Surface Plasmon Biacore. Our results show that these new embelin analogs have good proapoptotic properties against selected cancer cells, often higher than the natural product itself. Further, this activity is not directly mediated by XIAP. Altogether these preliminary results demonstrate that for active embelin analogs, the two OH groups are not absolutely required for anticancer activity, opening new possibilities for the design of proapoptotic derivatives in these series.

Two new sesquiterpenoids from the rhizomes of Nardostachys jatamansi.

Phytochemical investigation of CHCl(3):MeOH (1:1) extract from the rhizomes of Nardostachys jatamansi led to the isolation of two new sesquiterpenoids (5 and 6), along with six known compounds (1-4, 7, and 8). The structures of two new compounds were established using IR, MS, 1D, and 2D NMR techniques. In addition, all the isolates were tested for their cytotoxicities against the A549 (lung cancer), DU-145 (prostate cancer), MCF-7 (breast cancer), and SK-N-SH (neuroblastoma).

Novel C-9, 9'-O-acyl esters of (-)-carinol as free-radical scavengers and xanthine oxidase enzyme inhibitors: synthesis and biological evaluation.

New compounds with hydrophyllic esters of (-)-carinol were synthesized and evaluated as xanthine oxidase enzyme inhibitors and antioxidants. Aliphatic esterfication of C-9,9'-OH groups of (-)-carinol resulted in lowering antioxidant and xanthine oxidase inhibitory activities. However certain aromatic acyl esters considerably improved the xathine oxidase inhibition. Aromatic esterification with electron withdrawing substitutions would preferred for improvement in XOD inhibition while retaining radical scavenging activity, electron withdrawing substitution led to the loss of free radical scavenging property and neutral substituents decrease the enzyme inhibitory potential.

Synthesis and biological evaluation of new piplartine analogues as potent aldose reductase inhibitors (ARIs).

As a continuation of our efforts directed towards the development of anti-diabetic agents from natural sources, piplartine was isolated from Piper chaba, and was found to inhibit recombinant human ALR2 with an IC(50) of 160 µM. To improve the efficacy, a series of analogues have been synthesized by modification of the styryl/aromatic and heterocyclic ring functionalities of this natural product lead. All the derivatives were tested for their ALR2 inhibitory activity, and results indicated that adducts 3c, 3e and 2j prepared by the Michael addition of piplartine with indole derivatives displayed potent ARI activity, while the other compounds displayed varying degrees of inhibition. The active compounds were also capable of preventing sorbitol accumulation in human red blood cells.

Simultaneous determination of bioactive compounds in Piper nigrum L. and a species comparison study using HPLC-PDA.

Piper nigrum L. is a traditional medicine widely used in India for illnesses such as constipation, diarrhoea, earache, gangrene, heart disease, hernia, hoarseness, indigestion, insect bites, insomnia, joint pain, liver problems, lung disease, oral abscesses, sunburn, tooth decay and toothaches. In this study, six bioactive compounds, namely piperine (1), pellitorine (2), guineensine (3), pipnoohine (4), trichostachine (5) and piperonal (6) were quantified in different extracts of P. nigrum L. and compared with those of P. longum L. and P. chaba Hunter. To evaluate the quality of P. nigrum, a simple, accurate and precise HPLC-PDA method was developed for the simultaneous determination of the above-mentioned six compounds. The separation was achieved by Phenomenex Luna RP C(18) column (150 × 4.6 mm, 5 µm, Phenomenex Inc, CA, USA) with a binary gradient solvent system of water-acetonitrile, at a flow rate of 1.0 mL min(-1) and detected at 210, 232, 262 and 343 nm. All six calibration curves showed good linearity (R (2) > 0.9966). The method was reproducible with intra- and inter-day variations of less than 2% and 5%, respectively. The results demonstrated that this method is simple, reliable and suitable for the quality control of these plants.

A new prenylated isoflavone from Derris scandens Benth.

The phytochemical study of the whole plant of Derris scandens (Leguminosae) has resulted in the isolation of a new isoflavone derivative, scandinone A (11), together with 11 known compounds (1-10, 12). Structural elucidations of these compounds were performed using spectroscopic methods especially 1D, 2D NMR, and mass spectral analyses. The alpha-glucosidase-inhibitory activity of the isolates was also evaluated.

Synthesis and insect antifeedant activity of plumbagin derivatives with the amino acid moiety.

A series of plumbagin derivatives (4a-4k) containing an amino acid moiety were synthesized under mild esterification conditions in excellent yields (35%-80%) and screened for their antifeedant activities in tobacco caterpillar (Spodoptera litura) and castor semilooper (Achaea janata) using a no-choice laboratory bioassay. The parent compound plumbagin lacked significant activity, but the analogues were effective in reducing feeding by two insect species. The introduction of an N-acetyl-l-amino acid side chain to the Michael adduct of plumbagin at the third position of the quinone moiety significantly increased antifeedant activity. Several of the analogues were also toxic or caused developmental abnormalities following topical administration.