title: Extracts from Acacia catechu suppress HIV-1 replication by inhibiting the activities of the viral protease and Tat.
abstract: BACKGROUND
  Acacia catechu (Mimosa family) stem bark extracts have been used traditionally as a dietary supplement as well as a folk medicine given its reported anti-inflammatory, immunomodulatory, hepatoprotective, antioxidant, anti-microbial and anti-tumor activities. The present study was undertaken to evaluate the anti-HIV-1 activity of the extracts from stem bark of A. catechu.
  
  
  METHODS
  The aqueous and 50% ethanolic extracts of A. catechu stem bark were prepared and 50% ethanolic extract was further fractioned by successively partitioning with petroleum ether, chloroform and n-butanol. All the extracts and fractions were evaluated for cytotoxicity and anti-HIV-1 activity using different in vitro assays. The active n-butanol fraction was evaluated for its inhibition against HIV-1 reverse transcriptase, integrase, protease, pro-viral genome integration and viral Tat protein mediated transactivation. The effect of n-butanol fraction on the induction of pro-inflammatory cytokines secretion in Vk2/E6E7 cells and transepithelial resistance in Caco-2 and HEC-1A cells was investigated.
  
  
  RESULTS
  The aqueous and 50% ethanolic extracts of A. catechu showed IC50 values of 1.8 ± 0.18 μg/ml and 3.6 ± 0.31 μg/ml, respectively in cell-free virus based assay using TZM-bl cells and HIV-1NL4.3 (X-4 tropic). In the above assay, n-butanol fraction exhibited anti-HIV-1 activity with an IC50 of 1.7 ± 0.12 μg/ml. The n-butanol fraction showed a dose-dependent inhibition against HIV-1NL4.3 infection of the peripheral blood lymphocytes and against HIV-1BaL(R-5-tropic) as well as two different primary viral isolates of HIV-1 infection of TZM-bl cells. The n-butanol fraction demonstrates a potent inhibitory activity against the viral protease (IC50 = 12.9 μg/ml), but not reverse transcriptase or integrase. Further, in Alu-PCR no effect on viral integration was observed. The n-butanol fraction interfered with the Tat-mediated Long Terminal Repeat transactivation in TZM-bl cells, mRNA quantitation (qRT-PCR) and electrophoretic mobility shift assay (EMSA). The n-butanol fraction did not cause an enhanced secretion of pro-inflammatory cytokines in Vk2/E6E7 cells. Additionally, no adverse effects were observed to the monolayer formed by the Caco-2 and HEC-1A epithelial cells.
  
  
  CONCLUSIONS
  The results presented here show a potential anti-HIV-1 activity of A. catechu mediated by the inhibition of the functions of the viral protein and Tat.
authors.lastname: Nutan
authors.forename: Manoj
authors.initials: M
authors.lastname: Modi
authors.forename: Charlene S
authors.initials: CS
authors.lastname: Dezzutti
authors.forename: Shweta
authors.initials: S
authors.lastname: Kulshreshtha
authors.forename: Ajay Kumar Singh
authors.initials: AK
authors.lastname: Rawat
authors.forename: Sharad Kumar
authors.initials: SK
authors.lastname: Srivastava
authors.forename: Swadesh
authors.initials: S
authors.lastname: Malhotra
authors.forename: Anjali
authors.initials: A
authors.lastname: Verma
authors.forename: Udaykumar
authors.initials: U
authors.lastname: Ranga
authors.forename: Satish Kumar
authors.initials: SK
authors.lastname: Gupta
mesh_terms: D000045:Acacia / Q000737:chemistry*; D000998:Antiviral Agents / Q000302:isolation & purification / Q000494:pharmacology*; D002478:Cells, Cultured; D017320:HIV Protease Inhibitors / Q000494:pharmacology*; D015497:HIV-1 / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D020128:Inhibitory Concentration 50; D008826:Microbial Sensitivity Tests; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D018547:Plant Stems / Q000737:chemistry; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000037:antagonists & inhibitors*
chemical_list: D000998:Antiviral Agents; D017320:HIV Protease Inhibitors; D010936:Plant Extracts; D054322:tat Gene Products, Human Immunodeficiency Virus