title: Anti-HSV-2 activity of Terminalia chebula Retz extract and its constituents, chebulagic and chebulinic acids.
abstract: BACKGROUND
  Development of new and effective therapeutics for sexually transmitted herpes simplex virus-2 (HSV-2) infection is important from public health perspective. With an aim to identify natural products from medicinal plants, in the present study, the potential of Terminalia chebula Retz was investigated for its activity against HSV-2.
  
  
  METHODS
  Fruits of Terminalia chebula Retz were used to prepare 50% ethanolic extract. In addition, chebulagic acid and chebulinic acid both purified from T. chebula were also used. The extract as well as purified compounds were first used to determine their in vitro cytotoxicity on Vero cells by MTT assay. T. chebula extract, chebulagic acid, chebulinic acid along with acyclovir were subsequently assessed for direct anti-viral activity, and their ability to inhibit attachment and penetration of HSV-2 to the Vero cells. In addition, their anti-HSV-2 activity was also determined by in vitro post-infection plaque reduction assay.
  
  
  RESULTS
  Cytotoxicity assay using Vero cells revealed CC50= 409.71 ± 47.70 μg/ml for the extract whereas chebulagic acid and chebulinic acid showed more than 95% cell viability up to 200 μg/ml. The extract from T. chebula (IC50= 0.01 ± 0.0002 μg/ml), chebulagic (IC50= 1.41 ± 0.51 μg/ml) and chebulinic acids (IC50= 0.06 ± 0.002 μg/ml) showed dose dependent potent in vitro direct anti-viral activity against HSV-2. These also effectively prevented the attachment as well as penetration of the HSV-2 to Vero cells. In comparison, acyclovir showed poor direct anti-viral activity and failed to significantly (p > 0.05) prevent the attachment as well as penetration of HSV-2 to Vero cells when tested upto 50 μg/ml. However, in post-infection plaque reduction assay, T. chebula extract, chebulagic and chebulinic acids showed IC50values of 50.06 ± 6.12, 31.84 ± 2.64, and 8.69 ± 2.09 μg/ml, respectively, which were much lower than acyclovir (71.80 ± 19.95 ng/ml).
  
  
  CONCLUSIONS
  The results presented herein suggest that T. chebula extract, chebulagic and chebulinic acids have higher direct antiviral activity against HSV-2 and efficacy to inhibit virus attachment and penetration to the host cells as compared to acyclovir. However, acyclovir is more potent to inhibit post-infection virus replication. Hence, T. chebula may be a useful candidate for developing alternative therapy for prevention of sexually transmitted HSV-2 infection. ᅟ.
authors.affiliation: Reproductive Cell Biology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110 067, India.|Present Address: Anatomy and Cell Biology, Medical Faculty, Saarland University, Homburg, Saar, Germany.
authors.forename: Ajay
authors.initials: A
authors.lastname: Kesharwani
authors.affiliation: Corporate R & D Centre, HLL Lifecare Limited, Akkulum, Thiruvananthapuram, Kerala, 695 017, India.
authors.forename: Suja Kizhiyedath
authors.initials: SK
authors.lastname: Polachira
authors.affiliation: Corporate R & D Centre, HLL Lifecare Limited, Akkulum, Thiruvananthapuram, Kerala, 695 017, India.
authors.forename: Reshmi
authors.initials: R
authors.lastname: Nair
authors.affiliation: Reproductive Cell Biology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110 067, India.
authors.forename: Aakanksha
authors.initials: A
authors.lastname: Agarwal
authors.affiliation: Reproductive Cell Biology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110 067, India.
authors.forename: Nripendra Nath
authors.initials: NN
authors.lastname: Mishra
authors.affiliation: Reproductive Cell Biology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110 067, India. skgupta@nii.ac.in.
authors.forename: Satish Kumar
authors.identifier: http://orcid.org/0000-0003-3717-0436
authors.initials: SK
authors.lastname: Gupta
mesh_terms: D000212:Acyclovir / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001578:Benzopyrans / Q000494:pharmacology* / Q000627:therapeutic use; D002522:Chlorocebus aethiops; D005638:Fruit; D005960:Glucosides / Q000494:pharmacology* / Q000627:therapeutic use; D006561:Herpes Simplex / Q000188:drug therapy / Q000821:virology*; D018258:Herpesvirus 2, Human / Q000187:drug effects*; D047348:Hydrolyzable Tannins / Q000494:pharmacology* / Q000627:therapeutic use; D020128:Inhibitory Concentration 50; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology* / Q000627:therapeutic use; D029766:Terminalia / Q000737:chemistry*; D014709:Vero Cells; D053585:Virus Attachment / Q000187:drug effects; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D001578:Benzopyrans; D005960:Glucosides; D047348:Hydrolyzable Tannins; D010936:Plant Extracts; C103481:chebulinic acid; C076178:chebulagic acid; D000212:Acyclovir
keywords: Anti-HSV-2 activity; Attachment assay; Penetration assay; Post-infection plaque reduction assay; Terminalia chebula