Chinese Medicine, 2010, 1, 31-38
doi:10.4236/cm.2010.12006 Published Online September 2010 (http://www.SciRP.org/journal/cm)
Antimicrobial Activity of Polyalthia longifolia (Sonn.) Thw.
var. Pendula Leaf Extracts Against 91 Clinically Important
Pathogenic Microbial Strains
Sumitra Chanda*, Rathish Nair
Phytochemical, Pharmacological and Microbiological Laboratory
Department of Biosciences, Saurashtra University, Rajkot, Gujarat, India
Received May 21, 2010; revised July 21, 2010; accepted July 26, 2010
Abstract
The methanol, acetone and 1,4-dioxan fractions of leaves of Polyalthia longifolia (Sonn.) Thw. were evalu-
ated for antibacterial and antifungal activity. 91 clinically important strains were used for the study which
were both clinical isolates as well as identified strains. Piperacillin and gentamicin were used as standards for
antibacterial assay, while nystatin and flucanazole were used as standards for antifungal assay. The antibac-
terial activity was more pronounced against gram positive bacterial and fungal strains. Poor activity was
shown against gram negative bacterial strains studied.
Keywords: Antibacterial, Antifungal, Polyalthia longifolia, Clinical Isolates, Organic Solvent Extracts
1. Introduction
Due to the increasing development of drug resistance in
human pathogens as well as the appearance of undesir-
able effect on certain antimicrobial agents, there is a
need to search for new agents. The world health organi-
zation in 1997 suggested that effective locally available
plants be used as substitutes for drugs. Research work on
medicinal plants be intensified and information on these
plants be exchanged. This thought will go a long way in
the scientific exploration of medicinal plants for the
benefit of man and is likely to decrease the dependence
on importance of drugs [1]. Polyalthia longifolia (An-
nonaceae) is a tree, which is widely distributed in Bang-
ladesh, Srilanka and throughout the hotter parts of India
[2]. In India, the seeds of this plant were used as febri-
fuge [3]. Literature survey revealed that most of the
plants of annonaceae family contain antitumor and
anticancer principles [4,5]. The bark is also used as a
febrifuge in the Balasore district of Orissa [6]. The ex-
tract of stem bark and the alkaloids isolated from this
were found to demonstrate a good antibacterial and
antifungal activities [7]. In the present study, antim-
icrobial potentiality of the P. longifolia leaves was in-
vestigated against a few clinically isolated as well as
standard microbial cultures.
2. Materials and Methods
2.1. Plant Material
Polyalthia longifolia (Sonn.) Thw. (Annonaceae) leaves
were collected in May, 2004 from Rajkot in the State of
Gujarat (Western India) and identified by comparison
with specimens (PSN 4) available at the Herbarium of
the Department of Biosciences, Saurashtra University,
Rajkot, Gujarat, India.
2.2. Extraction
Leaves of P. longifolia were collected, air dried and then
powdered in a homogenizer and 10 gm was used for dif-
ferent solvent extractions (Methanol, Acetone, N,
N-dimethylformamide); the sample was extracted in sol-
vent kept on a rotary shaker overnight, and then the fil-
trate was collected and centrifuged at 5000 rpm. The
solvent was then evaporated to dryness under reduced
pressure and the extracted compound left was used for
the antimicrobial assay. The percentage yield of 1,
4-dioxan, methanol and acetone extracts were 20.56,
29.30 and 13.52 respectively.
Microorganisms Studied 91 clinically important mi-
crobial strains which included 23 gram positive, 56 gram

S. CHANDA ET AL. 32
negative and 15 fungal strains were studied for the an-
timicrobial activity. These strains included both clinical
isolates as well as identified strains. The details of the
microorganisms used are shown in Table 1.
Table 1. List of bacterial and fungal strains studied for an-
timicrobial assay.
Sr. Strain Specimen
Gram Positive bacteria
1 Staphylococcus spps. [10] Sputum
2 Staphylococcus aureus [11] Pus
3 Staphylococcus aureus [13] Urine
4 Staphylococcus aureus [23] Pus
5 Staphylococcus spps. [26] Pus
6 Staphylococcus aureus [34] Sputum
7 Staphylococcus aureus [35] Tracheal
8 Staphylococcus aureus [36] Tracheal
9 Staphylococcus spps. [44] Sputum
10 Staphylococcus aureus [47] Ear swab
11 Staphylococcus aureus [48] Sputum
12 Staphylococcus aureus [55] Pus
13 Staphylococcus aureus [56] Pus
14 Staphylococcus aureus ATCC 25923 -
15 Staphylococcus epidermidis ATCC 12228 -
16 Staphylococcus subfava NCIM 2178 -
17 Bacillus cereus ATCC 11778 -
18 Bacillus subtilis ATCC 6633 -
19 Bacillus megaterium ATCC 9885 -
20 Micrococcus flavus ATCC 10240 -
Gram negative bacteria
21 Pseudomonas spps. [15] Sputum
22 Pseudomonas spps. [17] Pus
23 Pseudomonas fluorescence [18] Pus
24 Pseudomonas spps. [25] Urine
25 Pseudomonas spps. [27] Pus
26 Pseudomonas aeruginosa [30] Sputum
27 Pseudomonas spps. [37] Tracheal
28 Pseudomonas aeruginosa [38] Pus
29 Pseudomonas spps. [39] Wound swab
30 Pseudomonas fluorescence [40] Tracheal
31 Pseudomonas spps. [42] Pus
32 Pseudomonas spps. [43] Pus
33 Pseudomonas spps. [46] Sputum
34 Pseudomonas spps. [49] Sputum
35 Pseudomonas spps. [50] Tracheal secretion
36 Pseudomonas fluorescence [59] Urine
37 Pseudomonas aeruginosa ATCC 27853 -
38 Pseudomonas testosteroni NCIM 5098 -
39 Pseudomonas pseudoalcaligenes ATCC
17440 -
40 E.coli [14] Pus
41 E.coli [16] Urine
42 E.coli [21 ] Urine
43 E.coli [22] Urine
44 E.coli [24] Urine
45 E.coli [28] Pus
46 E.coli [31] Urine
47 E.coli [32 ] Stool
48 E.coli [33] Pus
49 E.coli [41] Urine
50 E.coli [45] Pus
51 E. coli [51] Urine
52 E. coli [58] Vaginal swab
53 E. coli [60] Urine
54 E. coli [61] Blood
55 E. coli ATCC 25922 -
56 Enterobacter spps. [1] Tracheal
57 Enterobacter spps. [8] Tracheal
58 Enterobacter aerogenes ATCC 13048 -
59 Klebsiella spps [6] Urine
60 Klebsiella spps [19] Sputum
61 Klebsiella aerogenes [52] Pus
62 Klebsiella spps. [54] Urine
63 Klebsiella aerogenes [57] Urine
64 Klebsiella pneumoniae NCIM 2719 -
65 Proteus mirabilis [4] Wound swab
66 Proteus spps. [53] Pus
67 Proteus mirabilis NCIM 2241 -
68 Proteus vulgaris NCTC 8313 -
69 Proteus morganii NCIM 2040 -
70 Providencia rettgeri [5] Pus
71 Citrobacter spps. [20] Pus

S. CHANDA ET AL. 33
72 Citrobacter freundii [29] Pus
73 Citrobacter freundii ATCC 10787 -
74 Alcaligenes fecalis ATCC 8750 -
75 Salmonella typhimurium ATCC 23564 -
Fungus
76 Candida albicans [1] Urine
77 Candida albicans [2] Sputum
78 Candida spps. [3] Sputum
79 Candida spps. [4] Sputum
80 Candida spps. [5] Urine
81 Candida albicans ATCC 2091 -
82 Candida albicans ATCC 18804 -
83 Candida glabrata NCIM 3448 -
84 Candida tropicalis ATCC 4563 -
85 Candida apicola NCIM 3367 -
86 Cryptococcus neoformans ATCC 34664 -
87 Cryptococcus luteolus ATCC 32044 -
88 Trichosporan beigelii NCIM 3404 -
89 Aspergillus flavus NCIM 538 -
90 Aspergillus candidus NCIM 883 -
91 Aspergillus niger ATCC 6275 -
2.3. Preparation of Samples
Methanol, acetone and 1,4-dioxan extracts were dis-
solved in 100% DMSO at a concentration of 25 mg/ml
and 12.5 mg/ml and were used as working stocks respec-
tively. Sterile discs (Hi-media Labs) were impregnated
with 20 µl of the stock solution. Gentamicin (10 µg/disc)
and Piperacillin (100 µg/disc) for bacteria; nystatin (100
units/disc) and flucanazole (10 µg/disc) (Himedia Labs)
for fungus were used as positive control and pure DMSO
was used as a negative control.
2.4. Antimicrobial Study
Antimicrobial activity was performed by agar disc diffu-
sion method [8,9]. The bacterial strains were grown in
nutrient broth while fungal strains were grown in MGYP
(Malt glucose yeast peptone) broth. Mueller Hinton agar
no. 2 was the media used to study the antibacterial sus-
ceptibility while Sabroaud agar was used to study the
antifungal susceptibility test. The cultures were grown
for 24 hours, and the turbidity of the culture was main-
tained according to the 0.5 MacFarland standards. The
inoculum’s size was 1 × 108 cells/ml.
2.5. Agar Disc Diffusion
The media (Mueller Hinton Agar No.2 and MRS media)
and the test bacterial cultures were poured into Petri
dishes (Hi-Media). The test strain (200 µl) was inocu-
lated into the media (inoculums size 108 cells/ml) when
the temperature reached 40-42°C. The test compound (20
µl) was impregnated in to sterile discs (7 mm) (Hi-Media)
and was then allowed to dry. The disc was then intro-
duced into medium with the bacteria. The plates were
incubated overnight at 37°C for bacterial strains and
28°C for fungal strains. The experiment was performed
under strictly aseptic conditions. Microbial growth was
determined by measuring the diameter of the zone of
inhibition. The experiment was performed in triplicates
and the mean values of the result are shown in Table 2.
3. Results and Discussion
Herbal medicine in developing countries is commonly
used for the traditional treatment of health problems [10].
In recent years multiple drug resistance in human patho-
genic microorganisms has developed due to the indis-
criminate use of commercial antimicrobial drugs com-
monly used in the treatment of infectious diseases, mak-
ing it a global growing problem [11-13]. In addition to
this problem antibiotics are sometimes associated with
adverse effects on host including hypersensitivity, im-
mune suppression and allergic reactions [14]. Therefore
there is a need to develop alternative antimicrobial drugs
for the treatment of infections obtained from various
sources such as medicinal plants [15,16]. In the present
study, P. longifolia leaf extracts extracted in 1, 4-dioxan
(PDE), methanol (PME) and acetone extracts (PAE)
were investigated at two different concentrations for their
antimicrobial potentiality against 91 clinically important
microbial strains. All the three extracts (PDE, PME and
PAE at 500 µg/disc concentration) were active against
95% of the total gram positive bacterial strains studied.
PDE was active against 18.18% of the total gram nega-
tive bacterial strains studied (active against 21% of
Pseudomonas spps., 33.3% of Enterobacter spps., 16%
of Klebsiella spps., 33.3% of Proteus spps. and 66.6% of
Citrobacter spps.). PME and PAE were active against
12.72% of the total gram negative bacterial strains stud-
ied. P. aeruginosa is most common pathogen of im-
muno-compromised individuals [17]. Infections caused
by Pseudomonas spps. are among the most difficult to
treat with conventional antibiotics. Both PME and PAE
were active against 5.26% of the Pseudomonas spps. and
66.6% of Enterobacter spps. PME was active against
33.3% of Klebsiella spps. and Proteus spps., while PAE
was active against 66.6% of Klebsiella spps. and Proteus
spps. studied. Salmonellosis is an important public

S. CHANDA ET AL. 34
Table 2. Antimicrobial activity of Polyalthia longifolia against 91 clinically important microbial strains (inhibition zone in
mm).
Control Extracts Antibiotics
Sr.
No. Strain
DMSOPDE-500 PME-500PAE-500 PDE-250 PME-
250
PAE-
250 G Pc Fu Ns
Gram Positive
bacteria
1 Staphylococcus
spps. [10]
- 15 ±
0.58
12.67±
0.33
10 ±
0.58
10 ±
0.58
11 ±
0.58
14.67±
0.88 - - NT NT
2 Staphylococcus
aureus [11]
- 13 ±
0.58
12 ±
0.58
10 ±
0.58
11 ±
0.58
12 ±
1.15
12 ±
0.58
18.67±
0.33
17.33
±
0.33
NT NT
3 Staphylococcus
aureus [13]
- 12 ±
1.15
12 ±
2.31
9 ±
0.58 - - - - - NT NT
4 Staphylococcus
aureus [23]
- 11 ±
0.58
12 ±
1.73
9 ±
0.58
12 ±
1.73
9 ±
1.15 - - - NT NT
5 Staphylococcus
spps [26]
- 16.5 ±
0.28
11±
0.58
13±
0.58
15±
0.58
13 ±
1.73
14 ±
1.73 - - NT NT
6 Staphylococcus
aureus [34]
- 15.5 ±
0.28
9 ±
0.58
13 ±
0.58
14 ±
0.58
9 ±
0.58
10 ±
1.15 - - NT NT
7 Staphylococcus
aureus [35]
- 22±
0.28
12 ±
0.28
14 ±
0.58
17±
0.58
8 ±
0.58
11 ±
0.58 - - NT NT
8 Staphylococcus
aureus [36]
- 13 ±
0.58
9.67 ±
0.33
13 ±
0.58
12.67 ±
0.88 - 8.67± 0.88 - - NT NT
9 Staphylococcus
spps [44]
- 13 ±
0.58
10.33 ±
0.33
12.33 ±
0.33
18
0.58
11 ±
0.58
10.67
±
0.66
14.67±
0.33 - NT NT
10 Staphylococcus
aureus [47]
- 12 ±
3.21
10.67 ±
2.03
11 ±
2.31
9 ±
1.15
8.67 ±
0.88
12 ±
2.89 - - NT NT
11 Staphylococcus
aureus [48]
- - - - - - - 20.67±
0.33 - NT NT
12 Staphylococcus
aureus [55]
- 13.67 ±
0.33
12.67 ±
0.33
13.67 ±
0.33
11.67 ±
0.33 - - - - NT NT
13 Staphylococcus
aureus [56]
- 15.67 ±
0.33
10 ±
1.53
11.67 ±
0.88
12.33 ±
0.33
10.33
±
1.76
12.67
±
0.33
10.33±
0.33 - NT NT
14
Staphylococcus
aureus ATCC
25923
- 13 ±
0.58
8 ±
0.58
9 ±
0.58
14.33 ±
0.88
9.5 ±
0.28
9 ±
0.58 - - NT NT
15
Staphylococcus
epidermidis ATCC
12228
- 14.5 ±
2.60
16 ±
2.69 13 ± 0.5813.5 ± 0.87
13 ±
0.57
12 ±
1.73 - - NT NT
16
Staphylococcus
subfava NCIM
2178
- 10.5 ±
0.29
11.5 ±
1.44
12.5 ±
0.28 13 ± 2.319.5 ± 0.28
9.5 ±
0.28 -
20.17
±
0.44
NT NT
17 Bacillus cereus
ATCC 11778
- 29.5 ±
0.28
21.5 ±
0.28
25. ±
0.58 25 ± 2.3121 ± 0.58
25 ±
0.58
20.17
± 0.16
18.83
±
0.16
NT NT
18 Bacillus subtilis
ATCC 6633
- 26.5 ±
1.44
21.5 ±
1.44
23.5 ±
0.28 25 ± 0.5821 ± 0.58
21 ±
0.58
18.33
± 0.33
17.83
±
0.93
NT NT
19
Bacillus
megaterium ATCC
9885
-
14 ± 0.58 10.5 ±
0.28
12.5 ±
0.28 13 ± 0.5811 ± 0.58
10.5 ±
0.28 - - NT NT
20
Micrococcus
flavus ATCC
10240
- 12.5 ±
0.28
10.5 ±
0.28 11 ± 2.3111.5 ± 0.28
9 ±
0.58
9 ±
0.58
27.67
± 0.33
12.67
±
0.33
NT NT
Gram negative
bacteria
NT NT
21 Pseudomonas
spps. [15]
- - - - - - - 14 ±
0.58 - NT NT
22 Pseudomonas
spps. [17]
- 8 ±
0.58 - - - -
12 ±
2.89 - - NT NT
23 Pseudomonas
fluorescence [18]
- 8±
0.58 - - - -
12±
2.89 - - NT NT
24 Pseudomonas
spps. [25]
- - - - - - - - - NT NT

S. CHANDA ET AL. 35
25 Pseudomonas
spps. [27] - - - - - - - - - NT NT
26 Pseudomonas
aeruginosa [30] - -- - - - - -
16.67±
0.67 - NT NT
27 Pseudomonas
spps. [37] - -- - - - - - - -- NT NT
28 Pseudomonas
aeruginosa [38] - - - - - - -
19.67±
0.33 - NT NT
29 Pseudomonas
spps. [39] - - - - - - - - - NT NT
30 Pseudomonas
fluorescence [40] - - - - - - - - - NT NT
31 Pseudomonas
spps. [42] - - - - - - - - - NT NT
32 Pseudomonas
spps. [43] - - - - - - - - - NT NT
33 Pseudomonas
spps. [46] - - - - - - - - - NT NT
34 Pseudomonas
spps. [49] - 8 ± 0.58 - - - -
8 ±
0.58
20 ±
0.58 - NT NT
35 Pseudomonas
spps. [50] - - - - - - - - - NT NT
36 Pseuodmonas
fluorescence [59] - - - - - - - - - NT
NT
37
Pseudomonas
aeruginosa ATCC
27853
- - - - - - -
17 ±
1.15
12.33
±
0.66
NT NT
38
Pseudomonas
testosteroni NCIM
5098
- - - - - - -
22.33
± 0.66 - NT NT
39
Pseudomonas
pseudoalcaligenes
ATCC 17440
- 8.5 ±
0.86 14 ± 1.7310.5 ± 0.86 - - -
19.33
± 0.6 - NT NT
40 E.coli [14] - - - - - - - - - NT NT
41 E.coli [16] - - - - - - - - - NT NT
42 E.coli [21 ] - - - - - - - - - NT NT
43 E.coli [22] - - - - - - - - - NT NT
44 E.coli [24] - - - - - - - - - NT NT
45 E.coli [28] -
17±
0.33 NT NT
46 E.coli [31] - - - - - - - - - NT NT
47 E.coli [32 ] - - - - - - -
21±
0.58 - NT NT
48 E.coli [33] - - - - - - - - - NT NT
49 E.coli [41] - - - - - - -
18.67±
0.33 - NT NT
50 E.coli [45] - - - - - - - - - NT NT
51 E. coli [51] - - - - - - -
20.33±
0.33 - NT NT
52 E. coli [58] - - - - - - - - - NT NT
53 E. coli [60] - - - - - - - - - NT NT
54 E. coli [61] - - - - - - - - - NT NT
55 E. coli ATCC
25922 - - - - - - -
17.83
±
0.16
14.5
±
0.50
NT NT
56 Enterobacter spps.
[1] - - - - - - - - - NT NT
57 Enterobacter spps.
[8] - 15 ± 0.58
12 ±
0.58
14.33 ±
1.20
13 ±
0.58
12.33
±
0.88
12 ±
1.15
19.67±
0.88 - NT NT
58
Enterobacter
aerogenes ATCC
13048
- -
8.5 ±
0.86
15 ±
0.58 - - - - - NT NT
59 Klebsiella spps [6] - - - - - - -
22±
0.58 - NT NT
60 Klebsiella spps
[19] - - - - - - - - - NT NT
61 Klebsiella aero-
genes [52] - - -
8 ±
0.58
13 ±
1.73
11 ±
2.08 - - - NT NT

S. CHANDA ET AL. 36
62 Klebsiella spps.
[54] - - - - - - - - - NT NT
63 Klebsiella aero-
genes [57] - - - - - - - - - NT NT
64
Klebsiella pneu-
moniae NCIM
2719
- 12 ±
0.58
12 ±
0.58
10.5 ±
0.28
10.5 ±
0.86
10.5 ±
0.86
11 ±
0.58 -
24.67
±
0.33
NT NT
65 Proteus mirabilis
[4] - - - - - - - -
14±
0.58 NT NT
66 Proteus spps. [53] - - - - - -- - - - NT NT
67 Proteus mirabilis
NCIM 2241 - 10.5 ± 0.86
10.5 ±
0.28
9.5 ±
0.86 - - -
18.67
± 0.33 - NT NT
68 Proteus vulgaris
NCTC 8313 - - 9 ± 1.15 - - - - 18 ± 1.00 - NT NT
69 Proteus morganii
NCIM 2040 - 9 ± 0.58 - - 8 ± 0.58- - - - NT NT
70 Providencia rett-
geri [5] - - - - - - - - - NT NT
71 Citrobactor spps
[20] - 8 ± 0.58
8 ±
0.58
8 ±
0.58 - - - - - NT NT
72 Citrobactor
freundii [29] - - - - - - -
12.33±
0.33 - NT NT
73
Citrobactor
freundii ATCC
10787
- 11 ± 0.58 - - 11.5 ±
0.28
10 ±
0.58
9.5 ±
0.28 - - NT NT
74 Alcaligenes fecalis
ATCC 8750 - - - - - - -
18.33
± 0.66 - NT NT
75
Salmonella ty-
phimurium ATCC
23564
- - - - - - -
18.5 ±
0.28 - NT NT
Fungus
76 Candida albicans
[1] - 7.5 ± 0.29
8 ±
0.58 - 7.5 ± 0.29
10.5 ±
0.29
10 ±
0.58 NT NT -
11.33
±
0.33
77 Candida albicans
[2] - - -
10 ±
0.58
13.33 ±
0.88
9 ±
0.58 - NT NT -
18 ±
0.58
78 Candida spps. [3] - - -
9.5 ±
0.29
14.33 ±
0.66
12.5 ±
0.86
8 ±
0.58 NT NT - 14 ± 0.58
79 Candida spps. [4] - 11 ±
2.13
10.5 ±
2.02
11.5 ±
2.06
8 ±
0.58
8.5 ±
0.29
12.5 ±
0.86 NT NT - 14 ±
0.58
80 Candida spps. [5] - 7.5 ±
0.29
8.5 ±
0.29
9.5 ±
0.29
7.5 ±
0.29 - - NT NT -
10 ±
0.58
81 Candida albicans
ATCC 2091 - 11.5 ± 2.60
11 ±
2.31
8 ±
0.58
7.5 ±
0.29
7.5 ±
0.29
10.5 ±
2.02 NT NT
17.67
±
0.33
13 ±
0.58
82 Candida albicans
ATCC 18804 - 10.5 ± 0.29
8 ±
0.58 - -
11 ±
0.58
15 ±
1.15 NT NT -
14.33
±
0.33
83 Candida glabrata
NCIM 3448 - - - - - - - NT NT
39.67
±
0.88
22 ±
0.58
84 Candida tropicalis
ATCC 4563 - - -
7.5 ±
0.29
11 ±
0.58
12 ±
0.58
9.5 ±
0.29 NT NT -
8.33
±
0.33
85 Candida apicola
NCIM 3367 - 23 ± 3.60
26 ±
0.58
28 ±
1.15
25.33 ±
0.88
24 ±
0.58
21.66
±
0.33
NT NT -
21.33
±
0.88
86
Cryptococcus
neoformans ATCC
34664
- 7.5 ±
0.29
8 ±
0.58 - - -
9.5 ±
1.4 NT NT
21.33
±
0.33
17 ±
0.58
87
Cryptococcus
luteolus ATCC
32044
- 14 ±
0.58
11.5 ±
0.86
11 ±
1.15
9.5 ±
1.44
8.5 ±
0.86
8.5 ±
0.88 NT NT
23.66
±
0.88
17.66
±
0.88
88
Trichosporan
beigelii NCIM
3404
- 12 ±
0.58
13 ±
1.73
10.5 ±
2.02 - - - NT NT - -
89 Aspergillus flavus
NCIM 538 - - - -
14.67 ±
4.34
22 ±
0.58
10.33
± 2.02NT NT - -

S. CHANDA ET AL. 37
90 Aspergillus can-
didus NCIM 883 - 10.5 ± 0.29
9 ±
1.15
11 ±
0.58 - - - NT NT - -
91 Aspergillus niger
ATCC 6275 - - - -
11 ±
2.31 - - NT NT - -
Mean ± SEM, n = 3, zone includes disc diameter 7 mm; G – Gentamicin (10 µg/disc), Pc – Piperacillin (100 µg/disc), Ns – Nystatin (100 units/disc), Fu –
Fluconazole (10 µg/disc); PME – Methanol extract, PAE – Acetone extract, PDE – Dioxan extract, DMSO – Dimethylsulphoxide.
health problem worldwide. Salmonella infection is pri-
marily associated with gastroenteritis. This illness poses
a more serious health risk to sensitive populations in the
community such as the elderly, young and the immuno-
compromised, where hospitalization may be required.
All the three extracts were inactive against E. coli, A.
fecalis and S. typhimurium. Several antimycotic drugs
are available at present, its use is limited by a number of
factors such as low potency, poor solubility, emergence
of resistance strains and drug toxicity. Therefore there is
distinct need for the discovery of new, safer and more
effective antifungal agents. Candida species have be-
come a common cause of hospital acquired infections
and a large number of patients die as a result of invasive
Candidal infections [18]. All the three extracts were ac-
tive against 62.5% of the total fungal strains studied. The
three extracts were active against A. candidus while it
was inactive against the remaining two moulds (A. flavus
and A. niger) studied. The details of the results are given
elaborately in Table 2. From the results obtained, it
seems that the antibacterial action of the extracts is more
pronounced on gram positive than on gram negative
bacteria and these findings correlate with the observa-
tions of previous screenings of medicinal plants for an-
timicrobial activity, where most of the active plants
showed activity against gram positive strains only [19-
21]. This difference in susceptibility is because of the
difference in cell wall structure of gram positive and
gram negative organisms. The lipopolysaccharide con-
tent of gram negative bacteria makes them resistant to
plant extracts while the peptidoglycan layer of gram
positive bacteria is not an effective permeability barrier.
4. Conclusions
All the extracts of P. longifolia exhibited the highest
rates of antimicrobial activity against gram positive and
fungal strains studied. Therefore, it is concluded that P.
longifolia extracts should further be studied phyto-
chemically to elucidate the active principle in the leaf,
which can be used as a leading antibacterial (specific for
gram positive) and antifungal agent.
5. Acknowledgements
Financial support from Department of Special assistance
(DSA) project, New Delhi and supply of clinical isolates
by Micro Care and Spandan Diagnostic Laboratories,
Rajkot are gratefully acknowledged.
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