P.V. Srinivas

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.

Trifunctional N,N,O-Terdentate Amido/Pyridyl Carboxylate Ligated Pd(II) Complexes for Heck and Suzuki Reactions

Trifunctional N,N,O-terdentate amido/pyridyl carboxylate Pd(II) complexes were highly active and stable phosphine-free catalysts for Heck and room-temperature Suzuki reactions with high turnover numbers up to ca. 10(4).

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.

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).

Highly efficient and chemoselective cleavage of prenyl ethers using ZrCl4/NaBH4

Abstract An efficient and chemoselective deprotection of prenyl ethers of phenols and alcohols with ZrCl 4 /NaBH 4 in DCM was achieved in high yields. The selectivity of prenyl ether deprotection is well demonstrated by carrying out the reaction in the presence of several other ether and ester functionalities.

A new and convenient method for quantitative estimation of chrysophanol, an antioxidant in the rhizomes of Rheum emodi (Roxb)

Rheum emodi is an important medicinal plant widely used in the Unani system of medicine. A simple, precise and convenient HPTLC method has been developed for analysis of chrysophanol, an antioxidant and a major constituent of the rhizomes of Rheum emodi (Polygonacea) and pharmaceutical formulations of these. This method uses chrysophanol as internal standard. The stationary phase was silica gel 60F 254 , and hexane-ethyl acetate, 45 + 5 ( v/v ) was used as mobile phase. Detection and quantification were performed densitometrically at λ max = 366 nm. The method is characterized by high sensitivity and linearity over a wide concentration range. The results obtained were evaluated statistically.

Dolichandroside A, a new α-glucosidase inhibitor and DPPH free-radical Scavenger from Dolichandrone falcata seem

A new phenylpropanoid glycoside, dolichandroside‐A, together with seven known compounds α‐lapachone, lapachol, aloesaponarin II, 8‐hydroxydehydroiso‐α‐lapachone, β‐sitosterol, 3,8‐dihydroxydehydroiso‐α‐lapachone and verbascoside were isolated from the active ethyl acetate soluble extract of heartwood of Dolichandrone falcata. All except for dolichandroside‐A are known compounds, but have been isolated for the first time from this plant. The structure of all these compounds was determined on the basis of 1D‐ and 2D‐NMR spectral data. All the isolates were tested for α‐glucosidase inhibitory and DPPH radical scavenging activity. This is the first report identifying DPPH scavenging activity and α‐glucosidase inhibitory activity in D. falcata. Furthermore, along with a new compound, dolichandroside‐A, this study also assigns for the first time α‐glucosidase inhibitory activity to verbascoside and aloe saponarin‐II. Copyright

A New, Convenient Method for Quantitative Analysis of Hedychenone, an Anti-Inflammatory Compound in the Rhizomes of Hedychium spicatum (Buch-Hem)

Plants of the Hedychium genus are perennial rhizomatus plants belonging to the Zingiberaceae family. Extracts of Zingiberacaea have long been used in traditional medicine. A simple, precise, and convenient HPTLC method has been established for analysis of hedychenone, the major marker compound extracted from the rhizomes of Hedychium spicatum (Buch-Hem). Chromatography was performed on silica gel 60F254 plates with ethyl acetate-hexane, 20 + 80 (v/v), as mobile phase. Detection and quantification were performed densitometrically at λmax = 254 nm with hedychenone as external standard. The method is characterized by high sensitivity and linearity over a wide range of concentrations.

A Simple and Convenient Method of Standardization of Piper longum - An Ayurvedic Medicinal Plant

The dried fruits of Piper longum are extensively used in Ayurvedic medicinal preparations. A simple and convenient HPTLC method has been developed for standardization of the plant material using the two major constituents, pellitorine and dihydropiperlonguminine, as markers. The stationary phase was silica gel 60 F254, hexane–ethyl acetate, 75 + 25 (v/v), was used as mobile phase, and detection was at λ = 260 nm. The method is characterized by high sensitivity and linearity over a wide range of concentrations. The results obtained were evaluated statistically.

A new method of synthesis and Antibacterial activity evaluation of piper amides

Several natural piper amides and their mimics were synthesized by developing a new strategy of amide formation. The piper amides were tested against both gram +ve and gram −ve bacterial strains and found that they are particularly more active against Staphylococcus aureus and Chromobacterium violaceum strains.