Mechanism of antibacterial action of the alcoholic extracts of Hemidesmus indicus (L.) R. Br. ex Schult, Leucas aspera (Wild.), Plumbago zeylanica L., and Tridax procumbens (L.) R. Br. ex Schult.

Kongari Saritha,Angireddy Rajesh,Oruganti H Setty,Khanapur Manjulatha,Suresh Yenugu

doi:10.3389/fmicb.2015.00577

Abstract

Herbal products derived from Hemidesmus indicus (L.) R. Br. ex Schult, Leucas aspera (Wild.), Plumbago zeylanica L., and Tridax procumbens (L.) R. Br. ex Schult. are widely used in traditional medicine. Though the extracts of these plants were found to be antimicrobial in nature and have the potential to be used in clinics, the mechanism of action of is not reported. The ethanolic extracts of Hemidesmus indicus (L.) R. Br. ex Schult, Hemidesmus indicus ethanolic extract (HIEE), Leucas aspera (Wild.), Leucas aspera ethanolic extract (LAEE), Plumbago zeylanica L., Plumbago zeylanica ethanolic extract (PZEE), and Tridax procumbens (L.) R. Br. ex Schult, Tridax procumbens ethanolic extract (TPEE) were tested for their antibacterial activity against E. coli. Antibacterial activity was analyzed by CFU assay and the effect on the bacterial membrane by fluorescence activated cell sorting and scanning electron microscopy. LAEE, PZEE, and HIEE displayed potent bacterial killing activity in a time and concentration dependent manner. TPEE did not display appreciable antibacterial activity. The antibacterial action involved disruption of membrane potential, inner membrane permeabilization, blebbing and leakage of cellular contents. Our results contribute to the understanding of the antibacterial mechanism of alcoholic extracts of the medicinal plants used in this study.

Highlights

Complementary and alternative forms of medicine (CAM) have been practiced through out the world for centuries
Phytochemical Screening The phytochemical composition of the plant extracts used in this study (HIME, Leucas aspera ethanolic extract (LAEE), Plumbago zeylanica ethanolic extract (PZEE), and Tridax procumbens ethanolic extract (TPEE)) was evaluated to determine the variations in the composition of alkaloid, flavonoid, steroid, saponin, and phenolic content
Flavonoid content was found to be highest (845 ± 0.061) in PZEE followed by LAEE (610 ± 0.011), TPEE (340 ± 0.024), and HIME (75 ± 0.022)

Summary

Introduction

Complementary and alternative forms of medicine (CAM) have been practiced through out the world for centuries. Treatment strategies that involve use of natural products derived from plants has gained importance and this is primarily to overcome the side effects of allopathic forms of medicine. The National Health Interview Survey (NHIS) conducted by the Centers for Disease Control and Prevention (CDC) in 2007 indicate that around 40% of adults in the United States used some form of complementary and alternative medicine, indicating that such medical practices are prevalent even in the developed nations (Barnes et al, 2008). Medicinal plants continue to play an important role in CAM treatment strategies since they produce a wide variety of natural compounds with high therapeutic value (Nostro et al, 2000). Certain plant compounds such as arteether, nitisinone, and tiotropium are currently involved in late-phase clinical trials (Balunas and Kinghorn, 2005)

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Conclusion