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Year : 2017  |  Volume : 8  |  Issue : 1  |  Page : 53-55  

Poor antimicrobial activity of methanol and ethanol extract of leaves of Solanum trilobatum Linn.

1 Unit of Pharmacology, Faculty of Pharmacy, AIMST University, Bedong, Malaysia
2 Unit of Pharmaceutical Technology, Faculty of Pharmacy, AIMST University, Bedong, Malaysia

Date of Web Publication21-Apr-2017

Correspondence Address:
Subramani Parasuraman
Units of Pharmacology, Faculty of Pharmacy, AIMST University, Bedong, Kedah
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jpnr.JPNR_7_17

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How to cite this article:
Parasuraman S, Chuen LY, Hoong SS, Wei DL, Zou LN, Loshini S. Poor antimicrobial activity of methanol and ethanol extract of leaves of Solanum trilobatum Linn. J Pharm Negative Results 2017;8:53-5

How to cite this URL:
Parasuraman S, Chuen LY, Hoong SS, Wei DL, Zou LN, Loshini S. Poor antimicrobial activity of methanol and ethanol extract of leaves of Solanum trilobatum Linn. J Pharm Negative Results [serial online] 2017 [cited 2020 Jul 5];8:53-5. Available from:

Dear Sir,

The prevalence of contagious ailment and infections via antibiotic-resistant pathogens elevated greatly over the last few decades. The ever-growing situation of antimicrobial resistance is indeed poses an alarming threat to public health worldwide. World Health Organization (WHO) reports propose that overcoming the antibiotic resistance is the prime issue for WHO in the coming millennium.[1] In old days, plants are most commonly used as the remedy for most known infections and systemic illness. Screening of plants for antimicrobial agents has gained wide attention. Over hundreds of chemical compounds are derived from plants and used as remedial agents to treat different illness. Plants which have medicinal values due to their health-enhancing and restorative ability are commonly known as herbs. Various pharmacologically active compounds are obtained from the plants and they are used as life-saving drugs.[2],[3] Presently, WHO has requested its member countries to contribute monetary aid for traditional practitioners to establish the traditional medical procedure. It is inevitable to employ both the traditional and modern medical procedure to conform the primary global health care.[4]

Solanum trilobatum Linn., (Thuthuvalai in Tamil; climbing brinjal in English) is a rare, perennial, medicinal herb included into the family of Solanaceae and its' parts, such as leaves, flowers and berries, are commonly used as remedies of respiratory ailment, such as cough and chronic bronchitis. S. trilobatum is a medicinal herbal used for treatment of asthma, hematemesis, diabetes mellitus and leprosy.[5] This plant also showed noteworthy hepatoprotective activity against carbon tetrachloride-induced hepatic damage in rats, antimicrobial activity against  Escherichia More Details coli, and Staphylococcus aureus and antifungal activity against Aspergillus flavus and A. niger.[6],[7] The antimicrobial activity of the methanol and ethanol extracts of leaves of S. trilobatum remains unclear; hence, the present study is planned to study the antimicrobial activities of methanol extract of leaves of S. trilobatum (MEST) and ethanol extract of leaves of S. trilobatum (EEST).

Taxonomically identified S. trilobatum plant was collected from rural areas of Vellore, Tamil Nadu, India between October and December 2016. Plant was then identified and authenticated by pharmacogenetics. The leaves of the plant were dried under the shade for a week and grounded using a grinder to coarse powder. The powdered dry leaves of S. trilobatum was packed in a soxhlet apparatus and extracted with methanol and absolute ethanol at 65°C. The extraction was considered complete when the solvent becomes clear. The extract was concentrated to a dry mass by evaporation under reduced pressure. The MEST and EEST were stored in a desiccator at room temperature.

The antimicrobial potency of MEST and EEST was tested by disk diffusion assay. The MEST and EEST were dissolved in a minimum volume of methanol and ethanol, respectively. The final concentrations (1, 0.1, 0.05, and 0.01 mg/mL) were made with sterile distilled water. A 1 mg/mL concentration of standard solution was prepared by dissolving 10 mg of gentamicin into 10 mL of sterile distilled water.

The antimicrobial activity of MEST and EEST were tested against five pathogenic microorganisms namely Bacillus cereus (ATCC ® 10876), Enterococcus faecalis [ATCC ® 14506], E. coli [ATCC ® 10799], Pseudomonas aeruginosa [ATCC ® 10145], and S. aureus (ATCC ® BAA-1026). These strains were obtained from Microbiologics KWIK-STIK™. By using stock, the primary culture was prepared and used for the preparation of subcultures of microorganism. Subculture in broth showed turbidity after 18h incubation. Standardization of inoculums was performed based on the spectrophotometer readings at OD 600 nm. Blank was prepared using Mueller–Hinton broth for B. cereus, E. faecalis, E. coli, P. aeruginosa, and S. aureus. The amount of overnight culture required to obtain culture at an OD 600 nm of 0.05 was calculated using the equation M1 × V1 = M2 × V2 to give inoculum concentration of 4.0 × 107 cells/mL. After dilution, the broths were kept on ice to prevent further bacterial growth.

The screening for antimicrobial activity was performed by employing disk diffusion method using Mueller–Hinton agar for all the tested organisms. Disks containing known amounts (1, 0.1, 0.05, and 0.01 mg/mL of MEST/ EEST or 1 mg/mL of gentamicin) of the extracts and they were placed on the surface of the agar plate. The plates were inoculated at 36±1°C for ≃ 18 h or until a strain to give a confluent lawn of growth was observed. The antimicrobial substance diffused into the medium produced a zone of inhibition (ZI) around the disk. Its diameter was measured in millimetre (mm). The assay was duplicated for three times and the average was calculated.

Antimicrobial potential of extracts were assessed in terms of ZI of microbial growth and the results was summarized [Table 1]. MEST showed antimicrobial activity against S. aureus at 0.1 mg/mL onward and MEST 1 mg/mL showed antimicrobial activity against E. coli and E. faecalis. EEST did not show any antimicrobial activity against E. coli, S. aureus, B. cereus, E. faecalis, and P. aeruginosa at a concentration of 0.01, 0.05, and 0.1 mg/mL and has an antimicrobial activity against E. coli, S. aureus, and E. faecalis at 1 mg/mL concentration, whereas gentamicin showed antimicrobial activity against E. coli, S. aureus, B. cereus, E. faecalis, and P. aeruginosa at 1.0 mg/mL.
Table 1: Antimicrobial activity of MEST and EEST

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Latha and Kannabiran[8] also studied the antimicrobial activity of S. trilobatum against S. aureus, B. subtilis, E. coli, and Klebsiella species. The aqueous extract of S. trilobatum is active against S. aureus (ZI = 8 mm), B. subtilis (ZI = 9 mm), and Klebsiella species (ZI = 10 mm), whereas methanol extract of stem of S. trilobatum is active against S. aureus (ZI = 11 mm).[8] The phytochemical analysis of the extracts of S. trilobatum showed presence of carbohydrates, amino acid, fats and oils, saponins, flavonoids, alkaloids, tannins, and phenolic compounds, and the antimicrobial activity of the extract may be presence of secondary metabolites and tannins.[9] Gentamicin is an aminoglycoside antibiotic agent, traditionally used for the treatment of wide range of aerobic gram-negative pathogenic infections and also used empirically in suspected sepsis. Gentamicin retained its bactericidal activity against stationary-phase of bacterial growth and inhibits bacterial protein synthesis via irreversible binding to the 30S bacterial ribosome.[10],[11] In present study, gentamicin showed antibacterial action against few gram-positive strains namely S. aureus and B. cereus and the same was reported elsewhere.[12],[13] The antibacterial action of gentamicin against gram-positive microbes are concentration-dependent.

MEST and EEST are not showing favorable antimicrobial activity against E. coli, B. cereus, and P. aeruginosa. Both the extracts have antimicrobial activity against S. aureus and E. faecalis at 1 mg/mL concentration.

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Conflicts of interest

There are no conflicts of interest.

   References Top

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Lahlou M. The success of natural products in drug discovery. Pharmacol Pharm 2013;4:17-31.  Back to cited text no. 2
Parasuraman S, Thing GS, Dhanaraj SA. Polyherbal formulation: Concept of ayurveda. Pharmacogn Rev 2014;8:73-80.  Back to cited text no. 3
Oliver SJ. The role of traditional medicine practice in primary health care within Aboriginal Australia: A review of the literature. J Ethnobiol Ethnomed 2013;9:46.  Back to cited text no. 4
Doss A, Dhanabalan R. Preliminary phytochemical screening and antibacterial studies of leaf extract of Solanum trilobatum Linn. Ethnobotanical Leaflets 2008;12:638-42.  Back to cited text no. 5
Shahjahan M, Vani G, Shyamaladevi CS. Effect of Solanum trilobatum on the antioxidant status during diethyl nitrosamine induced and phenobarbital promoted hepatocarcinogenesis in rat. Chem Biol Interact 2005;156:113-23.  Back to cited text no. 6
Nagarajan SM, Kandasamy S, Chinnappa R. Comparative antimicrobial activity of callus and natural plant extracts of Solanum trilobatum L. Anc Sci Life 2009;28:3-5.  Back to cited text no. 7
Latha PS, Kannabiran K. Antimicrobial activity and phytochemicals of Solanum trilobatum Linn. Afr J Biotechnol 2006;5:2402-4.  Back to cited text no. 8
Parasuraman S, Yu Ren L, Chik Chuon BL, Wong Kah Yee S, Ser Qi T, Shu Ching YJ, et al. Phytochemical, antimicrobial and mast cell stabilizing activity of ethanolic extract of Solanum trilobatum Linn. leaves. Malays J Microbiol 2016:12359-64.  Back to cited text no. 9
Mascio CT, Alder JD, Silverman JA. Bactericidal action of daptomycin against stationary-phase and nondividing Staphylococcus aureus cells. Antimicrob Agents Chemother 2007;51:4255-60.  Back to cited text no. 10
Gonzalez LS, Spencer JP. Aminoglycosides: a practical review. Am Fam Physician 1998;58:1811-20.  Back to cited text no. 11
Sørensen TS, Sørensen AI. Bactericidal activity of gentamicin against S. aureus. In vitro study questions value of prolonged high concentrations. Acta Orthop Scand 1993;64:82-4.  Back to cited text no. 12
Bottone EJ. Bacillus cereus, a volatile human pathogen. Clin Microbiol Rev 2010;23:382-98.  Back to cited text no. 13


  [Table 1]


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