Duvvuru Gunasekar

Dihydroechioidinin, a flavanone from Andrographis echioides

Abstract A reinvestigation of the whole plant of Andrographis echioides has led to the isolation of a new flavanone, dihydroechioidinin together with four known flavones, echioidinin, echioidin, skullcapflavone I 2′- O -methyl ether, and skullcapflavone I 2′- O -glucoside. The structure of dihydroechioidinin was established as (2 S )-5,2′-dihydroxy-7-methoxyflavanone on the basis of spectral and chemical evidence.

Two acylated flavone glucosides from Andrographis serpyllifolia

Abstract Two new acylated flavone glucosides, skullcapflavone I 2′-O-β- d -(3″-E-cinnamoyl)glucopyranoside and skullcapflavone I 2′-O-β- d -(2″-E-cinnamoyl)glucopyranoside, together with skullcapflavone I 2′-O-β- d -glucopyranoside and andrographidine C have been isolated from the whole plant of Andrographis serpyllifolia. Structural elucidation of the glycosides was achieved by various NMR techniques including 1H–1H COSY, HMQC, HMBC and ROESY experiments, FAB-mass spectrometry, acid hydrolysis and saponification.

Total synthesis of heliannone A and (R,S)-heliannone B, two bioactive flavonoids from Helianthus annuus cultivars.

The total synthesis of heliannone A (1) and (R,S)-heliannone B (2), two bioactive flavonoids originally isolated from Helianthus annuus cultivars, is described.

Androechin, A New Chalcone Glucoside from Andrographis Echioides

Abstract A new chalcone glucoside, androechin, and a known flavone glucoside, echioidinin 5-O-glucoside, were isolated from the whole plant of Andrographis echioides. Androechin was characterized as 2,2′,6′-trihydroxy-4′-methoxychalcone 2′-O-β-D-glucopyranoside by spectral and chemical studies.

A New Naphthoquinone from Bombax Malabaricum

Abstract A new naphthoquinone 1 together with 7-hydroxycadalene (2) and 8-formyl-7-hydroxy-5-isopropyl-2-methoxy-3-methyl-1,4-naphthoquinone (3) were isolated from the heartwood of Bombax malabaricum. The new naphthoquinone was characterized as 7-hydroxy-5-isopropyl-2-methoxy-3-methyl-1,4-naphthoquinone (1) based on spectral and chemical studies.

A new biflavonoid from Ochna beddomei

A new biflavonoid, 2,3-dihydroochnaflavone 7,4′,7″-tri-O-methyl ether (1) together with two known biflavonoids namely, 2,3-dihydroochnaflavone (2) and ochnaflavone (3) were isolated from the stem bark of Ochna beddomei. The structures were determined by means of spectral and chemical studies.

A biflavonoid from Cycas beddomei

A new biflavanone, tetrahydrohinokiflavone, together with amentoflavone has been isolated from the leaves of Cycas beddomei. The structures were established on the basis of spectral and chemical evidence.

Flavone O- and C-glycosides of Rhynchosia beddomei

Abstract A new flavone- O -glycoside isolated front the leaves of Rhynchosia beddomei has been characterized as 3′,4′-di- O -methylluteolin-7- O -glucuronide.

Phytochemical and Biological Studies of Ochna Species

The genus Ochna L. (Gr, Ochne; wild pear), belonging to the Ochnaceae family, includes ca. 85 species of evergreen trees, shrubs, and shrublets, distributed in tropical Asia, Africa, and America. Several members of this genus have long been used in folk medicine for treatment of various ailments, such as asthma, dysentery, epilepsy, gastric disorders, menstrual complaints, lumbago, ulcers, as an abortifacient, and as antidote against snake bites. Up to now, ca. 111 constituents, viz. flavonoids (including bi‐, tri‐, and pentaflavonoids), anthranoids, triterpenes, steroids, fatty acids, and a few others have been identified in the genus. Crude extracts and isolated compounds have been found to exhibit analgesic, anti‐HIV‐1, anti‐inflammatory, antimalarial, antimicrobial, and cytotoxic activities, lending support to the rationale behind several of its traditional uses. The present review compiles the informations concerning the traditional uses, phytochemistry, and biological activities of Ochna.

Tirumalin, a new prenylated dihydroflavonol from Rhynchosia cyanosperma.

Abstract A new dihydroflavonol has been isolated together with the known flavonol- O - glycosides, rutin and kaempferol-3-rutinoside, and (+)-pinitol from the leaves of R. cyanosperma Benth. The dihydroflavonol was identified as (+)-(2 R , 3 R )-8- C -prenyltaxifolin-7, 4′-dimethyl ether on the basis of spectroscopic studies and the compound given the trivial name tirumalin.