Tuberculosis (TB) is a chronic infectious disease caused by a set of closely related mycobacterial strains such as Mycobacterium tuberculosis, M. bovis, M. africanum and others, known collectively as the M. tuberculosis complex (MTC) [1]. M. tuberculosis is responsible for more human mortality than any other single microbial species [2]. According to estimates by World Health Organization (WHO), almost 9 million new cases and 1.4 million TB deaths occurred in 2011 [3]. Although there are efective anti-tubercular agents, the misuse of these drugs in addition to inconsistent or partial treatment have led to the development of multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB). Te resistant strains coupled with drug hepatotoxicity and lengthy therapy paved the way for TB therapeutic crisis [4-7]. Tis situation presently acts as a serious challenge to the health care system. Tus it becomes necessary to prioritize the search for new antimycobacterial agents worldwide [8,9]. A number of extracts and isolated compounds from plants are being tested in this context. Te literature reports the antimycobacterial activity of many classes of natural products such as alkanes, phenolics, acetogenic quinines, favonoids and triterpenes [10,11]. Several researchers have studied the possible use of certain plant extracts in the treatment of TB [12]. In vitro Antioxidant and Antimycobacterial Activity of Seeds of Piper long- um Linn: A comparative Study Barua CC 1* , Singh A 2 , Sen S 1 , Barua AG 2 and Barua IC 3 1 Department of Pharmacology and Toxicology, Khanapara, Guwahati, India 2 Veterinary Public Health, College of Vety Science, Assam Agricultural University, India 3 Department of Agronomy, College of Agriculture, Assam Agricultural University, Jorhat, Assam, India * Corresponding author: Barua CC, Department of Pharmacology and Toxicology, Assam Agricultural Universi- ty, Tel: +91 98640-13231, Fax: 91-361-2337700 (O), E-mail: chanacin@gmail.com Citation: Barua CC, Singh A, Sen S, Barua AG, Barua IC (2014) In vitro Antioxidant and Antimycobacterial Activity of Seeds of Piper longum Linn: A comparative Study. SAJ Pharm Pharmacol 1: 101. doi: 10.18875/2375- 2262.1.101 Piper longum, belonging to the family Piperaceae, have been reported to have pharmacological and clinical importance. Te present study was undertaken to compare the in vitro antioxidant and antimycobacterial activity of chloroform, ethyl-acetate, hexane, ethanol, hydro-ethanol and aqueous extracts of seeds of Piper longum in order to establish the most active extract for further study. All the six extracts were screened for antioxidant activity using in vitro screening models viz. scavenging activity of DPPH radical, nitric oxide, hydroxyl radical; reductive ability and ABTS assay. Ascorbic acid served as reference standard. Te extracts were also screened for antimycobacterial activities against M. smegmatis in order to authenticate the folklore claims of its use against non tuberculous bacteria. Various plant secondary metabolites were found to be present in the extracts in diferent proportions. Mycobacterium smegmatis (non- tuberculous bacteria) was found to be sensitive against chloroform (PC), ethanol (PE), ethyl-acetate (PEA) and hexane (PH) extracts. Te mean minimum inhibitory concentration (MIC) of diferent extracts were in the increasing order of PC>PE=PH>PEA. MIC of PC, PH, PE, PEA was found to be 8, 16, 16 and 32 mg/mL, respectively and minimum bactericidal concentration (MBC) was calculated as 20.23, 33.43, 36.23 and 64.09 mg/mL, respectively. Chloroform extract of Piper longum (PC) showed the highest in vitro antioxidant activity as well as antimycobacterial activity. Abstract Keywords: Antioxidant activity; Antimycobacterial activity; DPPH; Hydroxyl radical scavenging activity; Nitric oxide scavenging activity; Piper longum; Phytochemicals Article history: Received: 02 May 2014, Accepted: 10 June 2014, Published: 12 August 2014 RESEARCH ARTICLE Open Access Introduction Volume 1 | Issue 1 ScholArena | www.scholarena.com SAJ Pharmacy and Pharmacology ISSN: 2375-2262 Phytomedicines have been utilized in the treatment of infectious diseases since the dawn of medicine [6]. Te success of plant products in drug discovery can be attributed to their chemical diversity, the biological pressure to create bioactive molecules, the structural similarity of the protein targets across many species and so on [13]. Phenolics are the largest group of phytochemicals that account for the antioxidant and antimicrobial activities in plants or plant products [14]. Antioxidants decrease oxidative stress and minimize the incidence of pathological conditions caused by the oxidants. Te generation of oxidative stress is harmful to the