This document discusses the antibacterial activity of phytochemicals isolated from various plants. It begins by defining phytochemicals as biologically active chemical compounds found naturally in plants. It then describes different types of phytochemicals like alkaloids, flavonoids, phenolics, and terpenes. The document examines the antibacterial mechanisms and activity of phytochemicals from several plants against pathogens. It finds that phytochemicals inhibit microbes through various mechanisms like disrupting membranes and inhibiting energy metabolism. The phytochemicals from plants like garlic, citrus, peppermint, and moringa show activity against bacteria like MRSA and E. coli. The document concludes that optimizing these compounds

1. ANTIBACTERIAL ACTIVITY OF ISOLATED
PHYTOCHEMICALS
(MICRO-591)
Maninderjeet kaur
L-2008-BS-09-IM
M.Sc. Int. (Hons.) Microbiology
Punjab Agricultural
University,Ludhiana

2. PHYTOCHEMICALS
 “Phyto” - plant.
 Naturally occurring, biologically active chemical
compounds in plants.
 Phytochemicals are beneficial to human health as
responsible for the disease protection through various
modes of action.

3.  More than 4000 of these compounds have been
discovered to date and it is expected that scientists
will discover many more.

4. TYPES OF PHYTOCHEMICALS
 Alkaloids
 Glycosides
 Flavonoids
 Phenolics
 Tannins
 Terpenes
 Essential Oils
 Phyto-estrogens
 Phytosterols

5. ALKALOIDS
 Largest group of secondary chemical constituents
 Made from ammonia compounds
 Basically of nitrogen bases synthesized from amino
acid

6. Plant-derived alkaloids in clinical use are
 Morphine
 Codeine

7. SOME SCREENING METHODS FOR THE
DETECTION OF ALKALOIDS
Reagents/Test Composition Result
Meyer’s Reagent Potassium mercuric
iodide solution
Cream precipitate
Wagner’s Reagent Iodide in potassium
iodide
Reddish-brown
precipitate
Tannic Acid Tannic acid Precipitate
Hager’s Reagent A saturated solution of
picric acid
Yellow precipitate

8. GLYCOSIDES
 Condensation products of sugars
 Colorless, crystalline carbon, hydrogen and
oxygen- containing water-soluble phytochemicals
 Found in cell sap

9. Plant-derived glycosides are:-
 α- Terpineol
 Cinnamyl acetate
 β- glucosid

10. FLAVONOIDS
 Important group of polyphenols
 Widely distributed among the plant flora
 Found in almost all plant based food and beverages
 Level depending in degree of ripeness, variety and
processing
 >4000 distinct flavonoids identified

11. Nearly present in 70% of plants.
 Quercetin, Kaempferol and Quercitrin
Other group include
 Flavans
 Flavonods
 Anthocyanidins
 Catechin
Anthocyanidins

12. PHENOLICS
 Chemical compounds occur as natural color
pigments
 Responsible for the color of fruits of plants
 Have multiple functions
Classified into-
 Phenolic acids
 Flavonoid polyphenolics (flavones, flavonones)
 Non-flavonoid polyphenols

13. CAFFEIC ACID is regarded as most common
phenolic compound distributed in plant flora.

14. TANNINS
 Widely distributed in plant flora
 Phenolic compounds of high molecular weight
 Found in root, bark, stem and outer layers of plant
tissues
 Gallic acid- plant derived

15. TERPENES
 Most widespread
 Chemically diverse group of natural products
Major plant derived-
 β- Caryophyllene
 Terpenolen
 α- cubebene

16. ESSENTIAL OILS
 Odorous and volatile products
Major plant derived are-
 Eugenol
 Gein
 Senigrin
 Amygdalin

17. PHYTOESTROGENS
 Naturally occurring
 Resemble mammalian oestrogen
 Iso- flavonone -associated with cancer prevention,
improved cardio-vascular health and improved
bone health.

18. PHYTOSTEROLS
 Most abundant in the seeds of green and yellow
vegetables.
 Important in human diet-reduce cholesterol and
facilitate excretion from the body

19. TOP TWELVE PHYTO FOODS
 Soy
 Tomato
 Broccoli
 Garlic
 Flax seeds
 Citrus fruits
 Melons: cantaloupe,
watermelon
 Pink grapefruit
 Blueberries
 Sweet potatoes
 Chili peppers
 Legumes: beans, and
lentils

20. MECHANISM OF ACTION OF PHYTOCHEMICALS
 Inhibit microorganisms
 Interfere with metabolic processes
 Modulate gene expression
 Modulate signal transduction pathways
 Chemotherapeutic with chemo-prevention referring
to the use of agents to inhibit, reverse or retard
tumourgensis.

21. MECHANISM OF ACTION

22. SOME SPECIFIC MODES OF ACTIONS
 Anti-oxidants
 Anti-carcinogenic
 Anti-ulcer
 Anti-diabetic
 Anti-inflammatory
 Antimicrobial activity

23. ANTIMICROBIAL ACTIVITY
 Protect against pathogenic insects, bacteria, fungi
or protozoa.
 Phenolics helping in the reduction of particular
adherence of organisms to the cells lining the
bladder which reduces UTIs.
 Exert bacteriostatic or bactericidal activity on
microbes.

24.  Volatile gas combinations of cinnamon and clove oil
inhibit growth of spoilage fungi, yeast and bacteria.
 Antimicrobial activity varies for the same plant part tested
due to geographical location, nutrient content and
extraction methods.

25. ANTIBACTERIAL ACTIVITY MECHANISMS OF
VARIOUS PHYTOCHEMICALS
1.Inhibition of nucleic acid-
 DNA synthesis strongly inhibited by flavonoids in
Proteus vulgaris
 RNA synthesis most affected in Staphylococcus
aureus.
 B-ring intercalates with the hydrogen bonding with
the stacking of nucleic acid bases and lead to
inhibitory action.
 DNA gyrase was inhibited in Escherichia coli. by
different phytochemicals.

26. 2. Inhibition of cytoplasmic membrane function
Sophoraflavanone G have antibacterial activity against
Methicilin-resistant Staphylococcus aureus and
streptococci.
Studied through liposomal model membranes lead to the
alteration of membrane fluidity in hydrophilic and
hydrophobic regions so reduce the fluidity of outer and
inner layers.

27.  A strong antibacterial catechin found in green tea.
 Catechin have greater activity against Gram-positive than
Gram-negative bacteria.
 Catechin perturb lipid bilayers by directly penetrating
them and disrupting the barrier function.

28. 3. Inhibition of energy metabolism
 Licochalcone (flavonoids) have inhibitory activity against
Staphylococcus aureus and Micrococcus luteus but not
against E.coli.
 Interferes with the energy metabolism as energy is
required for active uptake of various metabolites.
 Inhibit strongly oxygen-consumption in Micrococcus
luteus and Staphylococcus aureus but not in E.coli.

30. ANTIBACTERIAL ACTIVITY OF AQUEOUS
EXTRACT OF ALLICIN AGAINST METHICILLIN-
RESISTANT STAPHYLOCOCCUS AUREUS
 Allicin main biologically active
antimicrobial phytochemical
 produced in garlic extracts
 The allicin liquid tested for
antimicrobial activity against MRSA
using an agar well diffusion method.
 Determination of minimum inhibitory
concentration (MIC) and minimum
bactericidal concentration (MBC).

31. A TYPICAL ZONE OF INHIBITION
PRODUCED BY 500MG/ML ALLICIN
AGAINST MRSA.
 Allicin liquid was active
against S. aureus strains
at or above 62.5 μg/mL.
 No activity was detected
below 62.5 μg/mL
 Concentrations of 250
μg/mL and above are
most active.

32.  88% of strains have MICs for allicin at 16 μg/mL, and all
strains were inhibited by allicin at 32 μg/mL.
 The present study demonstrated that the majority (88%)
of strains have MBCs for allicin at 128 μg/mL and all the
strains were killed by allicin at 256 μg/mL.

33. PHYTOCHEMICALS OF CITRUS FRUITS
 Different solvent extracts (ethyl acetate, ethanol,
petroleum ether and water) showed the presence of
flavonoids, terpenoids, tannins and alkaloids from
citrus fruit peels and Citrus limon.

34. ANTIBACTERIAL ACTIVITY
 Against four pathogenic bacteria organisms (S.
aureus, E.coli, S. typhi and K. pneumonia )
 Acetone extract of Citrus sinensis shows maximum
zone of inhibition against E.coli (16mm) followed by
S. typhi (15mm), K. pneumonia (14mm) and S.
aureus (13mm) whereas the ethanol and aqueous
extract of Citrus sinensis not show such high
antibacterial activity.

35. Not all phytochemicals have equal antibacterial activity.
This is due to the difference in extraction process and
difference in plant parts.

36. PHYTOCHEMICALS OF MENTHA PIPERITA
L.(PEPPERMINT)
 Perennial and strongly
scented herb.
 Crude extracts from
different plant part is rich in
at least one of the alkaloids,
flavonoids, phenols,
tannins.
 Higher concentrations of
alkaloids were present in
the ethanol, methanol and
ethyl acetate leaf extracts
when compared to the stem
and root extracts.

37.  The antibacterial potential of six extracts from leaf, stem
and root are effective against bacteria such as B. subtilis,
S. pneumonia, S. aureus, E. coli, P. vulgaris and K.
pneumonia.
 Among all the extracts, ethyl acetate, chloroform and
ethanol leaf extracts showed high activity (7.2 - 15.3 mm
of zone of inhibition) on all organisms.
 The root extracts (chloroform, hexane and petroleum
ether) did not show any activity on S. pneumonia, S.
aureus, E. coli, P. vulgaris and K. pneumonia.

38. PHYTOCHEMICALS OF MEDICINAL
PLANTS(TULSI, CLOVE, NEEM AND DATIWAN)
 The percentage yield of the
phytochemicals in these
plants are-
 Tulsi-29.08%
 Clove-19.58%
 Datiwan- 21.07%
 Neem- 17.15%
Basically, alkaloids,
glycosides, terpenoids,
steroids, flavonoids, tannins
and reducing sugars were
there.

39.  Among four plants Clove is most effective against S.
typhi.
 All the plants were ineffective against E. coli and K.
pneumonia.
 The largest zone of inhibition (22 mm) obtained with
clove against S. typhi and Minimum Bactericidal
Concentration (MBC) value of 5 mg/l effective with Neem
against S. typhi
 K. pneumoniae and E. coli were found to be resistant
with all the plant extracts.

40. PHYTOCHEMICALS OF AMLA (EMBLICA
OFFICINALIS)
 The
phytochemicals
from the solvent
free extract of
Emblica officinalis
fruit as well leaf
are:-

41.  Isolated phytochemicals show antibacterial activity
against three respiratory pathogens i.e. Staphylococcus
aureus, Streptococcus pyogenes, Klebsiella
pneumoniae.
 Synergistic interactions are also important.
+++ : Highest synergistic activity ++ : Moderate synergistic activity, - :
Indifference

42. PHYTOCHEMICALS OF SWEITNIA
MAHAGONI
 Large deciduous and economically timber tree.
 The crude extract of this consists of

43.  The seed extract is active against 5 Gram positive and 9
Gram negative bacteria and 5 fungal strains.

44.  The extract is more active as compared to amoxicillin
against Bacillus thuringienesis and Pseudomonas
aeruginosa at 1mg/L.
 The MIC and MBC ranging form 12.5 to 50 mg/L and 25
to 50 mg/L for the SMCM seed extract respectively.

45. PHYTOCHEMICALS OF MORINGA OLEIFERA
 Commonly known as “Drumstick”.
 Highly nutritive vegetable in many
countries.
 Leaves contains phytochemicals
having potent anticancer activity.

46. Antimicrobial activity of Chloroform, Ethanol, Water extract of Moringa
oleifera against human pathogens

47.  The antibacterial activity of chloroform extract-
Maximum zone of inhibition (6 mm) against Escherichia Coli,
Salmonella typhii, No zone of inhibition against Pseudomonas
aeruginosa, Staphylococcus aureus.
 The antibacterial activity of ethanol extract
Maximum zone of inhibition (14 mm) against Salmonella
typhii and minimum inhibitory zone (8 mm) against
Escherichia Coli .
 The antibacterial activity of aqueous extract-
Maximum inhibitory zone (8 mm) against Staphylococcus
aureus. No inhibitory zone against Salmonella typhii,
Pseudomonas aeruginosa, Escherichia Coli.

48. CONCLUSION
 Future optimization of these compounds through
structure alteration allow the development of a
pharmacologically acceptable antimicrobial agent
and group of agents.
 The increasing acceptance of the chemical diversity
of natural products is well suited to provide the core
scaffolds for future drugs.
 There is need to be further developments in the use
of novel natural products and chemical libraries
based on natural products in drug discovery
campaigns