Bobbala Ravi Kumar

Acylated C-21 steroidal bisdesmosidic glycosides from Caraluma umbellata

From the whole plant of Caraluma umbellata, three new C-21 steroidal glycosides, named as carumbellosides III-V, were isolated and their structures elucidated by extensive spectroscopic experiments, devoid of any derivatisation, as caralumagenin 3-O-beta-D-glucopyranosyl(1-->4)-beta-D-digitalopyranoside-20-O-be ta- D-glucopyranoside, caralumagenin 3-O-beta-D-glucopyranosy(1-->4)- beta-D-digitalopyranoside-20-O-(2-O- benzoyl)-beta-D-glucopyranoside and caralumagenin 3-O-[6-O-benzoyl-beta-D-glucopyranosyl(1-->4)]-beta-D- digitalopyranoside-20-O-(2-O-benzoyl)-beta-D-glucopyranoside. The determination of the absolute configuration of the aglycone as (20 R), the conformations of the sugars and the unambiguous assignments of their NMR spectroscopic signals were achieved by a combination of 2D-NMR techniques. The isolates were devoid of significant cytotoxity in the UIC human cancer cell panel.

Bisdesmosidic pregnane glycosides from Caralluma lasiantha

Abstract From the whole plant of Caralluma lasiantha , two new bisdesmosidic C-21 steroidal (pregnane) glycosides, named as lasianthoside-A and -B, were isolated and their structures elucidated solely based on extensive 2D-NMR and MS/MS spectral analysis as caralasigenin 3- O -β- d -glucopyranosyl(1→4)-β- d -digitalopyranoside-20- O -α- l -rhamnosyl(1→6)-β- d -glucopyranoside and caralumagenin 3- O -β- d -glucopyranosyl(1→4)-β- d -digitalopyranoside-20- O -α- l -rhamnosyl(1→6)-β- d -glucopyranoside. In addition, a known flavonoid glycoside, luteolin neohesperidoside, was also isolated.

Pregnane Glycosides from Caralluma adscendens var. fimbriata

Eleven novel pregnane glycosides, 2–7 and 9–13, of which four, i.e., 10–13, comprised a new pregnane‐type genin exhibiting a hydroxymethylene instead of a Me group at C(19), and the known pregnane glycoside stalagmoside V (8) were isolated from whole plants of Caralluma adscendens var. fimbriata, a native Indian succulent plant. Their structures were elucidated by extensive 2D‐NMR spectroscopic studies.

Rapid identification of cytotoxic alkenyl catechols in Semecarpus anacardium using bioassay-linked high performance liquid chromatography–electrospray/mass spectrometric analysis

Two alkenyl catechols were rapidly identified as probable cytotoxic constituents from the petroleum ether extract of Semecarpus anacardium using HPLC–electrospray/MS analysis linked to bioassay. These compounds were then isolated from the same extract using semi-prep HPLC and were proven to be 1,2-dihydroxy-3-pentadeca-7′,10′-dienylbenzene and 1,2-dihydroxy-3-pentadec-8′-enylbenzene, respectively, by comparison with physico-chemical data in the literature. Both isolates showed cytotoxic activities against a panel of human cancer cell lines. Copyright

Cycloartane triterpenes from dikamali, the gum resin of Gardenia gummifera and Gardenia lucida.

We report on the chemical investigation of dikamali gum, which is the resin of Gardenia gummifera and G. lucida (Rubiaceae). Six new cycloartane triterpenes, dikamaliartanes A–F (1–6, resp.), together with a known flavonoid (7), were isolated and identified by NMR spectroscopy. All six cycloartanes are characterized by an open A‐ring with a free COOH group at C(3). In four of them, the C‐atoms C(23)–C(27) form a 4‐methylfuran‐2‐yl moiety. Bacterial assays using Staphylococcus aureus, Candida albicans, and Mycobacteria have been carried out but did not reveal significant activity.

Minor pregnanes from Caralluma adscendens var. gracilis and Caralluma pauciflora.

Phytochemical investigation of Caralluma adscendens var. gracilis and Caralluma pauciflora (Asclepiadaceae) whole plant extracts allowed to isolate one pregnane glycoside and two pregnanes characterized as 12β,20-O-dibenzoyl-5α,6-dihydrosarcostin β-oleandropyranosyl-(1→4)-β-cymaropyranosyl-(1→4)-β-digitoxypyranosyl-(1→4)-β-cymaropyranosyl-(1→4)-β-cymaropyranoside (1), 12β-O-benzoyl-3β,11α,14β,20R-pentahydroxy-pregn-5-ene (2), and 11α-O-benzoyl-3β,12β,14β,20R-pentahydroxy-pregn-5-ene (3), respectively. Their structural characterization was obtained on the basis of extensive NMR spectral studies. Three known pregnane glycosides along with lupeol and β-sitosterol were also isolated and characterized.

Flavonoids of Dikamali: A phytochemical reinvestigation.

Eleven known flavonoids (1–11) were isolated from Dikamali, the gum resin of Gardenia lucida. Three of them, desmethylnobiletin, pectolinarigenin and xanthomicrol, are a new report from this source. Nuclear magnetic resonance (NMR) data are being given for all the isolates. For two of them, viz., 3′,4′-dimethoxywogonin and 4′-hydroxywogonin, such data have not been reported in literature. Furthermore, correct NMR data are being provided for gardenin C as the data reported in literature were found to be incorrect.

Differentiating the Gum Resins of Two Closely Related Indian Gardenia Species, G. gummifera and G. lucida, and Establishing the Source of "Dikamali" by TLC

Dikamali is a gum resin obtained from the leaf buds of Gardenia lucida Roxb. or Gardenia gummifera L., family Rubiaceae. They are medium sized trees growing in various parts of India. The gum resin obtained from both these plants has the common vernacular name Dikamali. The resin exudes from the leaf buds in the form of yellow tears. It is marketed in herbal shops in the form of greenish-yellow lumps/cakes containing a number of leaf stalks. It has an offensive odor and a sharp pungent taste