Final Screening of Herbals

8/8/2019 Final Screening of Herbals

1/61


2/61

` Herb is a plant or a part of a plant valued for itsmedicinal, aromatic or savoury qualities.

` Herbal drugs - Finished, labelled medicinal productsthat contain as active ingredients aerial or

underground parts of plants, or other plant material, orcombinations thereof, whether in the crude state or asplant preparations.

` Plant material includes juices, gums, fatty oils,essential oils, and any other substances of this nature.

` Pharmacognosy is the scientific study of drugs fromnatural products.


3/61

` Herbal medicine or herbalism is the use of

herbs or herbal products for their therapeutic or

medicinal value.

` Herbal medicines may contain excipients in

addition to the active ingredients.

`

Medicines containing plant material combined withchemically defined active substances are not

considered to be herbal medicines.


4/61

Identified Actives

` Activity fully attributed to compound or class

` Sennosides in senna

Co-actives give some activity, not all

` Salicins in willow do not act alone

Markers strictly speaking are inactive

` No activity of the extract is attributable

` Agnuside in chaste tree


5/61

` The effectiveness of plant medicines.

` The preference of consumers for natural therapies,erroneous belief that herbal products are superior.

` A dissatisfaction with the results from synthetic drugs

` The high cost and side effects of most modern drugs.` Improvements in the quality, efficacy, and safety of herbal

medicines

` Patients belief that their physicians have not properlyidentified the problem; hence they feel that herbal remedies

are another option.` Amovement towards self-medication.


6/61

` Random collection and screening of material eg

paclitaxel, vincristine

` Ethnopharmacological knowledge eg artemisinin


7/61

` Botanical Identification and selection of medicinal

plants for the proposed Phytochemical Tests

` Extraction of the components (using Soxhlet extractorand cold percolation techniques)

` Separation of the constituents (using differentchromatographic techniques)

` Identification and quantification of the compoundswith the aid of thin layer chromatography (TLC)

` Subject extract to pharmacologically relevant assays


8/61

` Botanical identity like phytomorphology,

microscopical and histological analysis

(characteristic of cell walls, cell contents, starch

grains, calcium oxalate crystals, trichomes, fibers,vessels etc)

` Various histological parameters:

` Leaf constant: - Palisade ratio, Vein islet number,

Vein termination, Stomatal number, and Stomatalindex.


9/61

` Name of the plant (English, Regional names, Exactbotanical nomenclature)

` Part of the plant used

` Area of collection

` Distribution details

` Season ofCrop

` Time and year of collection

` Pesticide and insecticides

` Condition of the plant (fresh or dry)` Form of the plant (powdered or intact or cuttings like

etc.)


10/61

Maceration

` Powdered crude material is placed in a stopperedcontainer with the solvent and allowed to stand fora period of 24 to 48 hours with frequent agitationuntil soluble matter is dissolved.

` The mixture is then strained, the marc ( the dampsolid material) pressed and may be maceratedagain.

` Liquid is clarified by filtration or decantation afterstanding


11/61

Advantages

` Simple and cheap

` Solvent use is limited

` Can give good and selective extraction

Disadvantages` Analytes must be sufficiently soluble without

stirring/ slow heating


12/61

` Performed in a cone shaped vessel, (called

percolator) the narrow side of which is fitted with a

suitable filter and a stopcock,

` Plant material allowed to macerate with thespecified menstrum for a specified period in the

percolator after which the stopcock is opened so

that the percolate drips slowly from the bottom.

` Plant material is continuously flushed with freshsolvent


13/61

Advantages

` Exhaustive extraction possible

` Mild technique

Disadvantages

` Supervision is necessary

` Slow

` Large amounts of solvent required


14/61


15/61


16/61

` Method involves continuous extraction by boiling

organic solvents.

` Desired compound has a limited solubility in a

solvent, and the impurity is insoluble in thatsolvent

` Advantage -just one batch of solvent is recycled


17/61

Advantages

` Minimum solvent consumption

` Not much supervision is necessary

Disadvantages

` Harsh technique causing thermal decomposition

` Water and electricity is needed

` Less suitable for large scale operation


18/61

` 1: Stirrer bar2: Still pot(the still pot should not beoverfilled and the volumeof solvent in the still potshould be 3 to 4 times

the volume of the soxhletchamber) 3: Distillationpath 4: Thimble 5: Solid6: Siphon top 7: Siphonexit 8: Expansion adapter9: Condensor10:Cooling water in 11:Cooling water out


19/61

` Solvent is replaced with supercritical fluid

Advantages

` Mild technique

` Environment friendly and cheap` Can give fast extractions

` Extraction can be automated

` With 100 % CO2, there is no need for solvent

removal

` Solvating power variable via pressure


20/61

Disadvantages

` Less suitable for very polar products

` Rather complex apparatus is needed

` Involves high pressure` Less suitable for extraction of leaves

` Fresh plant materials are difficult to extract


21/61


22/61

` For temperature sensitive materials like natural

aromatic compounds

` When a mixture of two practically immiscible

liquids is heated, boiling points of the compoundsare depressed, allowing them to evaporate at

lower temperatures

` After distillation the vapors are condensed,

yielding water and the organic compounds.


23/61

Advantages

` Selective for volatile oils eg essential oils

` Very simple and cheap technique

` Only water is needed as solvent

` Well suitable for large scale extractions

`

Very clean extracts


24/61

` Only suitable for polar volatile oils

` Possible decomposition due to presence of water

and high temperatures

` Quantitative distillation is time-consuming


25/61


26/61

` Flavonoids

` Terpenes

` Steroids

` Glycosides` Amines

` Alkaloids

` Antibacterial

` Mycotoxins

` Saponins


27/61

` Quinones

` Tannins

` Phenolic compounds

` Fats` Carbohydrates

` Proteins

` Oleoresins

` Essential oils


28/61

` The extracts are then subjected to fractionation by

partition among solvents of different polarities or

can be directly put to chromatographic separation


29/61

` Feature common to all chromatographic methodsis the use of two phases, one stationary and theother mobile.

` Chromatographic methods may be classified

according to the nature of the stationary phase,which may be a solid or liquid.

` If the stationary phase is a solid the method isknown as adsorption chromatography;

` if a liquid, as partition chromatography.` the mobile phase may be either a liquid or a gas


30/61

TLC plates are inert supports (glass, plastic,aluminium) with a thin veneerofchromatographic media (silica)

Apply a concentrated drop of sample ()

with a capillary or dropping tube to bottom

of plate

Stand plate in a sealed vessel.

carefully add solvent(keep solvent level below sample).

Allow solvent to adsorb up the plate,

drawing the sample with it.


31/61


32/61


33/61

` When a plant extract is spotted on a fluorescent silicagel layer and exposed to UV light, it appears as spoton a fluorescent background, thus causing quenchingand is directly proportional to concentration of the

extract.

` Silica gel GF plate is used as an adsorbent forfluorescence quenching.

` Solvents taken- hexane toluene, ether, ethyl acetate,butanol, methanol and water


34/61


35/61

1930's UV (ultraviolet) light

1940's IR (infrared) spectroscopy

1950's NMR (nuclear magnetic resonance)

spectroscopy

1960's MS (mass spectrometry)

ESR (electron spin resonance)

ORD (optical rotatory dispersion)

C

D (circular dichroism)Advanced synthetic and biosynthetic technology

X-ray crystallography


36/61


37/61

Extract effective in the treatment of inflammations

of knee joints, motion sickness

Extract prepared using acetone as solvent and bypercolation

Column chromatography on silica gel

HPLC analysis of the extract and fraction


38/61


39/61


40/61


41/61


42/61


43/61


44/61

Plant material:

` Fresh leaves were collected from tropical area inYercaud and authenticated by horticulturist

Extraction:

` Shade dried, Powdered to obtain coarse powderand then passed through 60 mesh sieve.

` Continuous hot extraction.

` The extracts were evaporated to dryness

` Phytochemical screening were performed


45/61

` Healthy adult male Wistar rats between 2- 3m of

age and weighing about 150-200 g

` The animals were housed in polypropylene cages,

maintained under standard conditions (12 h light:12 h dark cycle; 30C; 35-60% humidity).

` They were fed with standard rat pellet diet and

water ad libitum.


46/61

` Normal healthy rats were divided into five groups

of six animals each.

` Different doses (100, 250, 500, 750 and 1000

mg/kg body weight) administered orally.` Observed continuously for 2 h for behavioral,

neurological, and autonomic profiles and after 24

and 72 h for any lethality


47/61

` Fasted overnight

` Intra peritoneal injection of streptozotocin

dissolved in 0.1M sodium citrate buffer pH4.5 at

the dose of 50mg/kg body weight.` Diabetes was confirmed after 48hrs

` Fasting blood glucose level more than 200mg/dl

were considered as diabetic rats and used for the

experimentation.` Grouped five days after induction of diabetes


48/61

` I: Normal control

` II: Diabetic control

` III: Diabetic rats methanolic extract 400mg/kg

` IV: Diabetic rats Glibenclamide 0.5mg/kg [orallyonce a day for 15 days]


49/61

` Fasted overnight

` Tail vein sample on the 5th day, 15th day and 20th

day post induction to determine blood glucose by

Glucose kit method.


50/61

` Preliminary phytochemical studies - phytosterols,

flavonoids and glycosides in methanolic extract of

Smilax zeylanica leaf

` Acute toxicity study no lethality up to

1000mg/kg.

` Oral leaf extract 400mg/kg body weight- significantdecrease (P


51/61

1. Herbal drugs are usually mixtures of many constituents.

2. The active principle(s) is (are), in most cases unknown.

3. Selective analytical methods or reference compounds may not

be available commercially.

4. Plant materials are chemically and naturally variable.

5. The methods of harvesting, drying, storage, transportation, and

processing (for example, mode of extraction and polarity of the

extracting solvent, instability of constituents, etc.) have an effect.


52/61

` Standardization of drug means confirmation of its identity

and determination of its quality and purity and detection

of nature of adulterant by various parameters like

morphological, microscopical, physical, chemical and

biological observations.


53/61

a. Quality control of crude drugs material, plant

preparations and finished products.

b. Stability assessment and shelf life.

c. Safety assessment; documentation of safetybased on experience or toxicological studies.

d. Assessment of efficacy by ethnomedical

informations and biological activity evaluations


54/61

1.Authentication (Stage of collection, parts of the plant

collected, regional status, botanical identity like

phytomorphology, microscopical and histologicalanalysis, taxonomical identity, etc.)

2.Foreign matter (herbs collected should be free from

soil, insect parts or animal excreta, etc.)

3.Organoleptic evaluation (sensory characters taste,

appearance, odor, feel of the drug, etc.)

4.Tissues of diagnostic importance present in the drug

powder.

5. Ash values.

6.Volatile matter

7.Moisture content determination


55/61

8. Chromatographic and spectroscopic evaluation.

TLC,HPTLC, HPLC methods -qualitative and

semi quantitative

9. Determination of heavy metals e.g. cadmium,

lead, arsenic, etc.

10. Pesticide residue DDT, BHC, toxaphene, aldrin

11. Microbial contamination


56/61

` Macroscopic methods

` Microscopic methods

` Physical methods

` Chemical methods` Biological methods


57/61


58/61

` Colour, odour, size, shape, taste and special

features including touch, texture etc

` Authentic specimen of the material under study

and samples of pharmacopoeial quality should beavailable to serve as a reference

` Simple, quick

` No preliminary treatment is necessary

` May vary from person to person and time to time


59/61


60/61

` To ensure that the plant is of the required species,

and that the right part of the plant is being used

` Pollen morphology may be used in the case offlowers to identify the species, and the presence

of certain microscopic structures such as leaf

stomata can be used to identify the plant part used

` Stinging nettle (Urtica urens) is a classic examplewhere the aerial parts are used to treat

rheumatism, while the roots are applied for benign

prostate hyperplasia


61/61

Final Screening of Herbals

Documents

Transcript of Final Screening of Herbals