Letters in Drug Design & Discovery   Reham Al-Harbi a , Mona Shaaban a,b,* , Razan Al-wegaisi a , Fatma Moharram c,d , Ola Abd El-Rahman e and Shahenda El-Messery c,f a Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmacy, Taibah University, Al Madinah Al Munawarah, Saudi Arabia; b Department of Microbiology and immunology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt; c Department of Pharmacognosy and Pharmaceutical Chemistry, Faculty of Pharmacy, Taibah University, Al Madinah Al Munawarah 30078, Saudi Arabia; d Department of Pharmacognosy, Faculty of Pharmacy, Helwan University, Helwan, Egypt; e Microbiology and Immunology Department, Faculty of Pharmacy (girls), Azhar University, Cairo, Egypt; f Department of Pharmaceutical organic Chemistry, Faculty of pharmacy, Mansoura University, Mansoura, 35516, Egypt Abstract: Background: High rate of bacterial infection potentiates scientists to search natural products for new antimicrobial agents. Methods: This research determines the antimicrobial activity of tannins isolated from Pimenta dioica leaves on Gram-positive and Gram-negative infectious organisms using agar diffusion method. Results: All tested compounds were effective against Staphylococcus epidermidis, particularly pedunculagin and nilocitin exhibited broad spectrum antibacterial effects against tested isolates as quantified by microtiter plate dilution method. Conclusion: This will open the era for in-vivo assessment of such compounds for clinical applica- tions. Keywords: Antimicrobial activity, pedunculagin, nilocitin, molecular docking, Pimenta dioica, tannins. 1. INTRODUCTION The development of microbial resistance among infec- tious pathogens represents a global threat to the medical community and public health. Treatment of bacterial infec- tion with Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae becomes more complex due to the lack of effective antibacterial therapy. Gram-positive bacte- rial infection especially with Staphylococcus aureus is cate- gorized as one of the main cause of nosocomial infection. Moreover, management of microbial infection associated with Bacillus cereus is getting more worthy with the disap- pearance of effective therapeutic approach. The severity of bacterial infection and the absence of effective therapy for the management of microbial resistance encouraged the sci- entists worldwide to explore the natural sources to eliminate *Address correspondence to this author at the Department of Pharmaceutics and Pharmaceutical technology, Faculty of Pharmacy, Taibah University, Al Madinah Al Munawarah 30078, Saudi Arabia and Department of Microbiology and immunology, Faculty of pharmacy, Mansoura University, Mansoura, Egypt; Tel: 009665340789, 00201066944268; E-mail: mona_ibrahem@mans.edu.eg microbial infection [1]. Extracts prepared from natural sources as well as pure compounds isolated from them as flavonoids, tannins, terpenoids, alkaloids, and saponin pro- vide a rich source for antimicrobial agents and are consid- ered as an important source for controlling bacterial resis- tance [2]. Pimenta dioica (L.) Merr, syn. Pimenta officinalis (Berg) L. (Myrtaceae) communally known as Jamaica or clove pep- per and traditionally known as allspice. It is an evergreen tree native to Caribbean island Jamaica, south and central America, southern Mexico and warm sub-continents. P. dioica has been reported to promote circulation and relieve muscle pain, arthritis and tiredness [3]. It was reported that Pimenta dioica is traditionally used to relieve indigestion, flatulence, common cold and bronchitis as well as it is used in cuisines as a spice, condiment and flavoring agent [4]. Various metabolites have been isolated from berries and leaves of P. dioica including tannins, phenyl proponoids and saponins [4, 5]. Polyphenols are widely distributed among different parts of the plant showing antiviral, antibacterial and antifungal effects. Polyphenols and tannins possess se- A R T I C L E H I S T O R Y Received: May 09, 2017 Revised: July 01, 2017 Accepted: July 26, 2017 DOI: 10.2174/1570180814666170810113850 1875-628X/18 $58.00+.00 ©2018 Bentham Science Publishers Send Orders for Reprints to reprints@benthamscience.ae 508 Letters in Drug Design & Discovery, 2018, 15, 508-515 LETTER ARTICLE Antimicrobial Activity and Molecular Docking of Tannins from Pimenta dioica Personal Use Only Not for Distribution