ASIAN JOURNAL OF CHEMISTRY ASIAN JOURNAL OF CHEMISTRY http://dx.doi.org/10.14233/ajchem.2016.19637 INTRODUCTION Phyllanthus amarus Linn., is a small erect, annual glabrous herb that belongs to the family Euphorbiaceae. It is widely grown in tropical and subtropical regions of the world and has a long history of use as a folkloric medicine in Asia and America [1]. It is commonly known as ‘Bhuinanvalah’ in Hindi and is used in Indian System of Medicine for the treatment of edema, stomach ache, intermittent fever, ophthalmology, diseases of urino-genital system, scabies, ulcer and wounds, etc. It is also used as a traditional medicine to cure liver diseases [2,3]. A number of previously isolated phytochemicals from the leaf, stem and root of the plant includes lignans, glycosides, flavo- noids, ellagitannins and phenylpropanoids along with common lipids, sterols and flavonols [4]. It has been reported that mainly lignans (phyllanthin, hypophyllanthin, niranthin and nirtetralin) are responsible for the liver protective activity of this plant [5]. The various parts of the plant have been a subject for nume- rous scientific studies owing to its proven hepatoprotective and antiviral activity against the hepatitis B virus. Therefore, the present study aimed to isolate and characterize the active principle from the whole plant which could be responsible for exhibiting hepatoprotective action. The present paper deals with the isolation, structure elucidation of the new diterpenoid 1 from the whole plant along with the prediction of its biological activity and molecular properties. Isolation and in silico Studies of New Diterpene from Phyllanthus amarus Linn. TANVEER ALAM 1 , BAHAR AHMED 1 , LUBNA NAJAM 2 and SHAH ALAM KHAN 1,3,* 1 Antihepatotoxic Research Lab, Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Jamia Hamdard, New Delhi-110 062, India 2 Department of Chemistry, D.A.V. College, Muzaffarnagar-251 001, India 3 Department of Pharmacy, Oman Medical College, Muscat, Sultanate of Oman *Corresponding author: E-mail: shahalamkhan@yahoo.com Received: 26 September 2015; Accepted: 21 December 2015; Published online: 30 January 2016; AJC-17766 We report herein the isolation of a new diterpenoid methyl labda-5(6),11(12),14(15)-triene-17-oate (1) from the whole plant of Phyllanthus amarus Linn for the first time. The structure of the isolated compound was established on the basis of IR, 1 H NMR, 13 C NMR and mass spectral studies. The in silico studies were carried out to predict the biological activity and to calculate bioactivity score, molecular and pharmacokinetic properties of isolated diterpene using Molinspiration and PASS cheminformatics software. The diterpene showed Pa values of 0.502 and 0.411 for antifungal and antihypertensive activity by PASS software. The bioactivity score obtained by Molinspiration indicated that the diterpene is most likely to act either as a nuclear receptor ligand or by enzyme inhibition. The compound was predicted to be lipophilic (mi log P = 5.3) and thus showed one violation of Lipinski’s rule of five. Keywords: Phyllanthus amarus, Diterpenoid, Euphorbiaceae, Labdane. Asian Journal of Chemistry; Vol. 28, No. 5 (2016), 1161-1163 EXPERIMENTAL The melting point was recorded using a Perfit melting point apparatus and is uncorrected. An IR spectrum was recorded in KBr pellet on Win IR FTS 135 instrument. Column chromatography was performed on silica gel (60-120 mesh) and thin layer chromatography on silica gel coated TLC plates. 1 H NMR spectra was recorded in DMSO on Bruker DRX 300 NMR spectrophotometer using TMS as an internal reference. Chemical shift values are expressed as δ ppm and coupling constant (J values) are expressed in Hz. 13 C NMR spectra was recorded on DRX-300 with TMS as an internal standard in 5 mm spinning tubes at 27 °C. A FAB mass spectrum was scanned at 70 eV on a Jeol D-300 instrument. The whole plant of Phyllanthus amarus was collected from Trivendrum, Kerala and identified by the Taxonomist of Department of Botany, Jamia Hamdard University, New Delhi, where a voucher specimen of the plant is deposited in the herbarium. Extraction and isolation: The air dried plant material (8 kg) was crushed to a coarse powder and extracted exhaustively by cold percolation method with ethanol (95 %). The alcoholic extract was concentrated under reduced pressure to yield a viscous mass (500 g). It was then dissolved in hot water and partitioned with petroleum ether (60-80 °C), acetone and methanol. The concentrated methanol soluble part was adsorbed on silica gel (60-120 mesh) to prepare slurry. The