Biomedical subjects
Publications and source records attributed to Y Venkateswarlu.
The ethanolic extracts of the dry fruits of Caesalpinia pulcherrima, aerial parts of Euphorbia hirta and flowers of Asystasia gangeticum were tested for antimicrobial activity. The three plants exhibited a broad spectrum of antimicrobial activity, particularly against Escherichia coli (enteropathogen), Proteus vulgaris, Pseudomonas aeruginosa and Staphylococcus aureus.
Two new bastadin alkaloids, bastadins-22 (1) and 23 (2), together with six known bastadins, bastadins-6 (3), -12 (4) (formerly basatadin-9), -14 (5), -15 (6), -16 (7), -19 (8), and a common steroid cholesterol were isolated from the sponge Dendrilla cactos. The structures of the isolates were established by the study of extensive spectroscopic analysis (1D and 2D NMR and MS data). Anticancer activity of the isolates has been carried out against Sup-T(1) cancer cells (T cell lymphoma).
Novel bis-andrographolide ether (1) and six known compounds andrographolide, 14-deoxy-11,12-didehydroandrographolide, andrograpanin, 14-deoxyandrographolide, (+/-)-5-hydroxy-7,8-dimethoxyflavanone, and 5-hydroxy-7,8-dimethoxyflavone have been isolated from the aerial parts of Andrographis paniculata and their structures were established by spectral data. All the isolates were tested for the anti-HIV and cytotoxic activity.
AIM: To study the antifungal activity and plant beneficial traits of a broad-spectrum antagonistic fluorescent pseudomonad strain, PUPa3. METHODS AND RESULTS: Strain PUPa3 was isolated from the rhizosphere soil of rice and identified as Pseudomonas aeruginosa on the basis of biochemical tests and by comparison of 16S rDNA sequences. This bacterium exhibits a broad-spectrum antifungal activity towards phytopathogenic fungi. The antifungal metabolite by PUPa3 was extracted, purified and characterized using nuclear magnetic resonance (NMR) and mass spectroscopy (MS). Production of indole-3-acetic acid (IAA), siderophores, phosphatase and protease in PUPa3 was determined. Strain PUPa3 did not produce hydrogen cyanide, cellulase and pectinase. CONCLUSION: The antifungal metabolite produced by PUPa3 has been identified as phenazine-1-carboxamide (PCN) on the basis of NMR and MS data. Strain PUPa3 showed a broad-spectrum antifungal activity towards a range of phytopathogenic fungi. This bacterium also showed several plant growth-promoting traits but did not show the traits attributed to deleterious rhizobacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Present study reports the production of PCN as well as IAA for the first time by a saprophytic P. aeruginosa strain PUPa3. Because of the production of siderophore, growth hormone, protease and phosphatase and its innate fungicidal potential, this strain can be used as biofertilizer and antagonist against a range of phytopathogenic fungi that infect rice, groundnut, tobacco, chili, mango, sugarcane, tea, cotton and banana.
Three new lamellarin alkaloids, lamellarins gamma (1), alpha (2), and epsilon (3), along with eight known lamellarin alkaloids, lamellarins M (4), K (5), K-diacetate (6), K-triacetate (7), U (8), I (9), C-diacetate (10), and X-triacetate (11), have been isolated from the Indian ascidian Didemnum obscurum. The structures of 1-11 were established using standard spectroscopic techniques. The structure of lamellarin K-triacetate (7) was further confirmed by X-ray crystallographic analysis. The antioxidant properties of lamellarin gamma, lamellarin gamma-monoacetate, lamellarins K, U, and I, and lamellarin C-diacetate were evaluated.
Four homoisoflavonoids, 4-O-methylsappanol (1), protosappanin A (2), brazilin (3) and caeasalpin J (4), isolated from Caesalpinia sappan, were tested for inhibitory activity against Beauveria bassiana. Compound 1 showed activity against this fungus.
The latex of Euphorbia nivulia afforded two ingol diterpenes 3,12-diacetyl-8-benzoylingol (4) and 3,12-diacetyl-7-benzoyl-8-nicotinylingol (5) along with three known ingol diterpenes 1, 2,and 3, and two known triterpenes cycloart-25-en-3beta-ol and cyclonivulinol. Their structures have been assigned on the basis of their structural data as well as their acetylated products. The diterpenes 1-5 were tested for the LPS induced PGE(2) inhibition activity.
Seco-sethukarailin (1), a novel diterpenoid, has been isolated along with known sesquiterpenes Delta(9(15))africanene, beta-elemene, african-1-ene, 6R,7R-6,7-epoxycaryophyll-3(15)-ene, and known diterpenoids sethukarailin and isomandapamate, from the soft coral Sinularia dissecta collected from Mandapam Coast, South India. The structure of the novel diterpenoid seco-sethukarailin (1) was characterized by interpretation of spectral data.
A new triterpenoid, 22,29xi-epoxy-30-norhopane-13beta-ol (1) was isolated together with six known compounds viz., fern-9(11)-en-6alpha-ol. fern-9(11)-ene, fern-9(11)-en-25-oic acid, fern-9(11)-en-28-ol, filicenol-B, adiantone and oxidation product of fern-9(11)-en-6alpha-ol obtained as 6-oxofern-9(11)-ene from the whole plant of Adiantum lunulatum, and their structures were elucidated by means of spectroscopic analysis and antibacterial evaluation of these compounds were conducted.
An immunosuppressive, tryptophan-derived alkaloid cristatin A (1), and two known compounds, cycloartenol and stigmasta-5,11(12)-diene-3 beta-ol, were isolated from the whole plant Lepidagathis cristata Willd. The structures of the isolates were established by interpretation of their spectral data.
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A short, first synthesis of melithasterol A (3) utilizing microwave irradiation-induced isomerization of 5alpha,8alpha-epidioxy steroid (1) as the key step has been achieved in 80% yield.
The sponge Mycale tenuispiculata afforded three new compounds-(6'Z)-5-(23'-cyano-6'-tricosenyl)pyrrole-2-carboxaldehyd e (1), mycaleoxime (2), and (6'E)-5-(6'-penta decenyl)pyrrole-2-carboxaldehyde (3)-and three known compounds, 3-formyl indole, an admixture of 5-alkyl pyrrole-2-carboxaldehydes, and thymidine. The structures of the above compounds were elucidated by the interpretation of their spectral data.
HIV-1 integrase is an attractive target for anti-retroviral chemotherapy, but to date no clinically useful inhibitors have been developed. We have screened diverse marine natural products for compounds active against integrase in vitro and found a series of ascidian alkaloids, the lamellarins, that show selective inhibition. A new member of the family named lamellarin alpha 20-sulfate (1), the structure of which was determined from spectroscopic data, displayed the most favorable therapeutic index. The site of action of lamellarin alpha 20-sulfate on the integrase protein was mapped by testing activity against deletion mutants of integrase. Inhibition of isolated catalytic domain was detectable though weaker than inhibition of full length integrase; possibly lamellarin alpha 20-sulfate binds a site composed of multiple integrase domains. Lamellarin alpha 20-sulfate also inhibited integration in vitro by authentic HIV-1 replication intermediates isolated from infected cells. Lamellarin alpha 20-sulfate was tested against wild type HIV using the MAGI indicator cell assay and found to inhibit early steps of HIV replication. To clarify the inhibitor target, we tested inhibition against an HIV-based retroviral vector bearing a different viral envelope. Inhibition was observed, indicating that the HIV envelope cannot be the sole target of lamellarin alpha 20-sulfate in cell culture. In addition, these single round tests rule out action against viral assembly or budding. These findings provide a new class of compounds for potential development of clinically useful integrase inhibitors.
Incubation of delta 9(15)-africanene with fungi Aspergillus niger and Rhizopus oryzae for 8 days yielded two oxidized derivatives, 10 alpha-hydroxy-delta 9(15)-africanene and 9 alpha,15-epoxyafricanane. The structure of the two products were assigned by interpretation of their spectral data.
Chemical examination of the soft coral Sinularia dissecta furnished five steroids (1-5), which include four new polyhydroxy steroids (2-5). The structures of new compounds have been established by the study of their spectral data. Steroid 5 was a novel polyoxygenated epoxy steroid.