J. Madhusudana Rao

Antimicrobial constituents from the rhizomes of Rheum emodi.

The bioassay-guided chemical examination of the rhizomes of R. emodi resulted in the isolation of two new oxanthrone esters, revandchinone-1, revandchinone-2, a new anthraquinone ether revandchinone-3 and a new oxanthrone ether, revandchinone-4. Their structures were established based on spectroscopic and degradative evidence. Occurrence of oxanthrone ether is reported for the first time. The anti bacterial and anti fungal activity of the isolates is studied.

A new sesquiterpene lactone from the roots of Saussurea lappa : Structure-anticancer activity study

The dried roots of Saussurea lappa, called costus roots, are used in the traditional system of medicine for the treatment of cancer. In our investigation for the anticancer constituents from the hexane extract of this plant, a new sesquiterpene (1) was isolated along with the known compounds costunolide (2), beta-cyclocostunolide (3), dihydro costunolide (4) and dehydro costuslactone (5). Their structures were established by the extensive spectroscopic analyses. In addition, costunolide and beta-cyclocostunolide derivatives were synthesized using Michael-type addition reaction of NaOMe to the alpha-methylene-gamma-lactone moiety. All the compounds were tested for their in vitro cytotoxic activity. Compound 1 exhibited potent cytotoxic activity and other compounds displayed moderate activity.

Gastroprotective flavonoid constituents from Oroxylum indicum Vent.

Chemical investigation of the stem bark of Oroxylum indicum resulted in the isolation and characterization of two new flavonoid glycosides (1, 2), along with seven known compounds (3-9). Their structures were established on the basis of extensive spectroscopic (IR, MS, 2D NMR) data analysis and by the comparison with spectroscopic data reported in the literature. In addition, all the compounds were tested for their ulcer protective effects against various gastric ulceritis inducing models in rats.

New Labdane diterpenes as intestinal α-glucosidase inhibitor from antihyperglycemic extract of Hedychium spicatum (Ham. Ex Smith) rhizomes

Phytochemical investigation of antihyperglycemic extract of rhizomes of Hedychium spicatum led to the isolation of two new labdane type diterpenes 2, 3 along with seven known compounds (1, 4-9). Their structures were established on the basis of NMR (1D and 2D) and mass spectroscopic analysis. The new compound 2 displayed strong intestinal alpha-glucosidase inhibitory activity. Other compounds also displayed varying degree of intestinal alpha-glucosidase inhibitory potential.

New furanoflavanoids, intestinal α-glucosidase inhibitory and free-radical (DPPH) scavenging, activity from antihyperglycemic root extract of Derris indica (Lam.)

A bioassay-guided fractionation and chemical examination of antihyperglycemic root extract of Derris indica resulted in isolation and characterization of two new furanoflavanoids (1, 2) along with thirteen known compounds (3-15). Their structures were determined on the basis of extensive spectroscopic (IR, MS, 1D and 2D NMR) data analysis and by comparison with the literature data. All the compounds were tested in vitro for intestinal alpha-glucosidase inhibitory and DPPH radical activity. New compounds (1, 2) displayed moderate intestinal alpha-glucosidase inhibitory as well as free radical scavenging activity. Other compounds also displayed varying degrees of moderate intestinal alpha-glucosidase inhibitory activity. Pongamol (6) displayed potent intestinal alpha-glucosidase inhibition.

Two new cytotoxic diterpenes from the rhizomes of Hedychium spicatum.

Phytochemical investigation of CHCl(3) extract of the rhizomes of Hedychium spicatum led to the isolation of two new labdane-type diterpenes, compounds 1 and 2 along with five known compounds (3-7). Their structures were established on the basis of NMR (1D and 2D) and mass spectroscopic analysis. In addition, all the isolates were tested for their cytotoxicity against the Colo-205 (Colo-cancer), A-431 (skin cancer), MCF-7 (breast cancer), A-549 (lung cancer) and Chinese hamster ovary cells (CHO). Two new compounds 1 and 2 were shown good cytotoxic activity.

Phytochemical investigation of labdane diterpenes from the rhizomes of Hedychium spicatum and their cytotoxic activity.

A comprehensive reinvestigation of chemical constituents from the rhizomes of Hedychium spicatum led to the isolation of two new labdane-type diterpene (1, 2), together with six known compounds (3-8). Their structures were established on the basis of extensive spectroscopic (IR, MS, 2D NMR) data analysis and by comparison with the spectroscopic data reported in the literature. In addition, all the isolates were tested for their cytotoxicity against the THP-1 (human acute monocytic leukemia), HL-60 (human promyelocytic leukemia), A-375 (human malignant melanoma) and A-549 (human lung carcinoma) cancerous cell lines.

Plant HDAC inhibitor chrysin arrest cell growth and induce p21WAF1 by altering chromatin of STAT response element in A375 cells

BackgroundChrysin and its analogues, belongs to flavonoid family and possess potential anti-tumour activity. The aim of this study is to determine the molecular mechanism by which chrysin controls cell growth and induce apoptosis in A375 cells.MethodsEffect of chrysin and its analogues on cell viability and cell cycle analysis was determined by MTT assay and flowcytometry. A series of Western blots was performed to determine the effect of chrysin on important cell cycle regulatory proteins (Cdk2, cyclin D1, p53, p21, p27). The fluorimetry and calorimetry based assays was conducted for characterization of chrysin as HDAC inhibitor. The changes in histone tail modification such as acetylation and methylation was studied after chrysin treatment was estimated by immuno-fluorescence and western blot analysis. The expression of Bcl-xL, survivin and caspase-3 was estimated in chrysin treated cells. The effect of chrysin on p21 promoter activity was studied by luciferase and ChIP assays.ResultsChrysin cause G1 cell cycle arrest and found to inhibit HDAC-2 and HDAC-8. Chrysin treated cells have shown increase in the levels of H3acK14, H4acK12, H4acK16 and decrease in H3me2K9 methylation. The p21 induction by chrysin treatment was found to be independent of p53 status. The chromatin remodelling at p21WAF1 promoter induces p21 activity, increased STAT-1 expression and epigenetic modifications that are responsible for ultimate cell cycle arrest and apoptosis.ConclusionChrysin shows in vitro anti-cancer activity that is correlated with induction of histone hyperacetylation and possible recruitment of STAT-1, 3, 5 proteins at STAT (−692 to −684) region of p21 promoter. Our results also support an unexpected action of chrysin on the chromatin organization of p21WAF1 promoter through histone methylation and hyper-acetylation. It proposes previously unknown sequence specific chromatin modulations in the STAT responsive elements for regulating cell cycle progression negatively via the induction of the CDK inhibitor p21WAF1.

Synthesis and biological evaluation of novel 8-aminomethylated oroxylin A analogues as α-glucosidase inhibitors

A series of 8-aminomethylated derivatives (1a-1j) were prepared by Mannich reaction of oroxylin A (1) with appropriate primary or secondary amines and para-formaldehyde. All the compounds were tested for their alpha-glucosidase inhibition activity against both yeast and rat intestinal alpha-glucosidase. Some of the compounds demonstrated significantly better alpha-glucosidase inhibitory activity than the parent compound (oroxylin A).

Bioactivity-guided isolation of cytotoxic constituents from stem-bark of Premna tomentosa.

A bioassay-guided fractionation and chemical investigation of the stem bark of Premna tomentosa resulted in the isolation and characterization of four new icetexane diterpenes (1-4), along with the known compounds coniferaldehyde (5), syringaldehyde (6), lupeol (7), betulin (8), and 2-(4-methoxyphenyl)-2-butanone (9). Their structures were established on the basis of extensive spectroscopic (IR, MS, 2D NMR) data analysis and by comparison with the spectroscopic data reported in the literature. The new compounds exhibited diverse functionalities on a common icetexane diterpene skeleton. In addition, cytotoxic activities of the icetexanes (1-3) were evaluated by determining their inhibitory effects on the human cancer cell lines (MCF-7, HT-29, Hep-G2, A-431, and A-549). Compounds 1 and 3 showed selective inhibitory activity against MCF-7 (15.96microg/mL and 15.84microg/mL) and HT-29 cell lines (16.21microg/mL and 14.57microg/mL), respectively.