Glycosides introduction


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Glycosides introduction

  1. 1. 1 GLYCOSIDES(ANTHRAQUINONES) Presented by; M Pharm (Pharmaceutical Chemistry) students Gunturu. Aparna Akshintala. Sree Gayatri Thota. Madhu latha Kamre. Sunil Daram. Sekhar University College Of Pharmaceutical Sciences Department Of Pharmaceutical Chemistry Acharya Nagarjuna University Guntur
  2. 2. 2 Glycosides  Definition: Organic natural compounds present in a lot of plants and some animals, these compounds upon hydrolysis give one or more sugars (glycone) β- form and non sugar (aglycone) or called genin.
  3. 3. 3 Glycosides  More important in medicine than a lot of drugs.  Occur in higher plant tissues in very small amounts  Also fungal and bacterial cells (exuded in medium) and animals  Formed by a biochemical reaction that makes a water insoluble compound more polar than a water soluble molecule  Hence can be removed from an organic system  Man forms them in the liver as part of the process of detoxification and they are excreted via urine  Mammalian glycosides are simple compounds whereas plant glycosides are much larger and chemically more complex
  4. 4. 4  Solubility:  Glycosides are water soluble compounds and insoluble in the organic solvents.  Glycone part: water soluble, insoluble in the organic solvents.  Aglycone part: water insoluble, soluble in the organic solvents.  Some glycosides soluble in alcohol.
  5. 5. 5 Separation between glycosides parts: Glycosides glycone +aglycone +HCl G + A +salt+H2O (H2O+G) + A (H2O+G) + (chloroform+A) We can separate them by using separating funnel. The best solvent to extract aglycone is Ethyl acetate because: A. Immiscible in water. B. Always presents in the upper layer. Neutralization by Using alkaline Filtration chloroform Hydrolysis +HCLdil
  6. 6. 6 Note: Alcohol and acetone are water miscible compounds , so we can't use them as organic solvents for aglycone separation.
  7. 7. 7 Physico-chemical properties of glycosides(general)  Colorless, solid, amorphous, nonvolatile (flavonoid- yellow, anthraquinone-red or orange).  Give positive reaction with Molisch's and Fehling's solution test (after hydrolysis).  They are water soluble compounds, insoluble in organic solvents.  Most of them have bitter taste. (except: populin, glycyrrhizin, stevioside).
  8. 8. 8  Odorless except saponin (glycyrrhizin).  when a glycosides has a lot of sugars its solubility in water decrease.  Glycosides hydrolyzed by using mineral acids and temperature or by using enzymes such as: a. Emolsin Bitter almond seeds. b. Myrosin or Myrosinase black mustard seeds. c. Rhamnase glycosides containing rhamnose as sugar part.
  9. 9. 9 The function or the role of glycosides in the plant organism  Converting toxic materials to non or less toxic.  Transfer water insoluble substances by using monosaccharide.  Source of energy (sugar reservoir).  Storing harmful products such as phenol.  Regulation for certain functions(growth).  Some have beautiful colours(pollenation process).
  10. 10. 10  Some glycosides have antibacterial activity, so they protect the plants from bacteria and diseases. Bitter almond Amygdalin bacteria HCNhydrolysis kill Eomlsin enzyme
  11. 11. 11 Classification of glycosides
  12. 12. 12 Classifications of glycosides according to their therapeutic effects  CHF(Congestive Heart Failure)and cardiac muscles stimulators such as: a. Digitalis glycosides: digoxin, digitoxin, gitoxin (Fox glove leaves). b. Ouabain: Strophanthus gratus seeds. c. K-strophanthin -Strophanthus kombe seeds. d. Scillaren A,B which isolated from red and white Squill bulbs. e. Convolloside:Convallaria majalis – Lily of the Valley.
  13. 13. 13  Laxative group of glycosides: a. Sennoside A,B,C,D (Senna leaves and fruits). b. Cascaroside A,B (Cascara bark). c. Frangulin and glucofrangulin(Frangula bark). d. Aloin and barbaloin (Aloe vera and Aloe barbadensis juice).
  14. 14. 14  Local irritant group: a. Sinigrin (Black mustered seeds-Brassica nigra) b. Sinalbin (White mustered seeds-Brasica alba)  Analgesics and antipyretics: Salicin Salisylic acid -Willow or Salix bark.  Keeping elasticity of blood vessels like: Rutin -Rutoside (Bitter orange peels, Lemon peels)  Anti-inflammatory group: a. Aloin for 1)acne 2)peptic ulcer b. Glycyrrhizin hydrolysis
  15. 15. 15 Classification of glycosides according to glycone part  Glucose -glucoside group like in Sennoside.  Rhamnose -Rhamnoside like in frangullin.  Digitoxose -Digitoxoside like in digoxin.  Glucose and Rhammnose Glucorhamnoside -glucofrangulin.  Rhamnose and glucose - Rhamnoglucoside -Rutin.
  16. 16. 16 Classification of glycosides on the basis of the linkage between glycone and aglycone part  O-glycosides : In these glycosides the sugar part is linked with a oxygen atom of aglycone .  S-glycosides : In these glycosides the sugar attached to a Sulfur atom of aglycone ,for example sinigrin.  N-glycosides : In these glycosides the sugar linked with Nitrogen atom of (-NH2,-NH-)amino group of aglycone ,for example nucleosides DNA,RNA.  C-glycosides : In these glycosides the sugar linked (condensed) directly to Carbon atom of aglycone ,for example aloin.
  17. 17. Most of glycoside may be named according to the plant from which they isolated for example: 1. Salicin from salix 2. Cascarosides from cascara 3. Aloin from Aloe vera 4. Sennosides from senna 5. Frangulin from frangula 6. Glycyrrhizin from glycyrrhiza GENERAL EXTRACTION PROCESS OF GLYCOSIDES;  Always glycosides founded in the plant with the enzymes which hydrolyzed them. We must damage these enzymes first to extract these glycoside by the following steps: STEP 1. Drying the plants fresh in special oven at 1000c for 30 minutes. STEP 2. Boiling them with organic solvents for 20 minutes STEP 3. Boiling them with acetone 5 minutes 17
  18. 18. 18 METHYL GLYCOSIDES  Methylglucoside is a monosaccharide derived from glucose. It can be prepared in the laboratory by the acid-catalyzed reaction of glucose with methanol.
  19. 19. 19 USES: chemical intermediate in the production of a variety of products including  Emollients.  Emulsifiers.  humectants.  moisturizers.  thickening agents.  plasticizers.  Surfactants.  varnishes and resins.
  20. 20. 20 Preparation of methyl glycoside STEP 1:  Methyl glucoside is prepared by the acid-catalyzed reaction of glucose and methanol .  In the reaction glucose, methanol and acid catalyst, anhydrous hydratable CaSO4 are required .  In the .preparation of methyl glycoside CaSO4 :glucose weight ratio of at least 1:1, maintaining the reaction mixture within the temperature range of about 50 C and 200 C until formation of methyl glucoside ceases.
  21. 21. 21  cooling the reaction mixture, neutralizing the acid catalyst with a base capable of forming a salt of neutralization which is insoluble in the reaction mixture . acid catalystC6 H12 O6 +CH3 OH⇋methylglucoside+H2 O (I)
  22. 22. 22 2. Process according to step 1, wherein the CaSO4 is incorporated in the reaction mixture in an amount sufficient to provide a CaSO4:glucose weight ratio from about 1:1 to about 3:1 3. Process according to step 1, wherein the CaSO4 :glucose weight ratio is from about 1:1 to about 2:1 4. Process according to claim 1, wherein the acid catalyst is H2 SO4. 5. Process according to step 4, wherein the base is selected from the group consisting essentially of Ca(OH)2, Mg(OH)2, Ba(OH)2, Sr(OH)2and mixtures there of. 6. Process according to step 1, wherein the reaction is carried out in a closed vessel within the temperature range of about 100 C and 150 C
  23. 23. 23 Anthraquinone Glycosides ( Anthraquinone Anthraquinone derivatives
  24. 24. 24 Aloe barbadensis Cassia senna Rhamnus purhsianus - Cascara Rheum palmatum. Chinese Rhubarb
  25. 25. 25 Introduction to Anthraquinones  Historically: Rhubarb, Senna, Aloes and Cascara were all used as purgative drugs.  Monocotyledons: Only Liliaceae. Most commonly C-glycoside: barbaloin.  Dicotyledons: Rubiaceae, Leguminosae, Polygonaceae, Rhamnace ae, Ericaceae, Euphorbiaceae, Lythraceae, Saxifraga ceae, Scrophulariaceae andVerbenacacea. Also in certain fungi and lichen.
  26. 26. 26  Reduced derivatives of anthraquinones  Oxanthrones, anthranols and anthrones  Compounds formed by the union of 2 anthrone molecules  Dianthrones  Aglycones:  Chrysophanol/Chrysophanic acid  Rhubarb and Senna.  Rhein  Rhubarb and Senna  Aloe-emodin  Rhubarb and Senna  Emodin  Rhubarb and Cascara
  27. 27. 27 Anthraquinones – Chemical Properties  Anthraquinone derivatives: orange-red compounds  Soluble in hot water/dilute alcohol.  Identified via Borntrager’s test  Powdered drug – macerated with ether  Filter  Add ammonia/caustic  Shake  pink, red or violet colour – positive for anthraquinone derivatives  If the Anthraquinones are reduced (within the herb) or stable (glycosides) test will be negative
  28. 28. 28 Anthraquinone Structure
  29. 29. 29 Anthranonls andAnthrones  Reduced anthraquinone derivatives.  Occur either freely (aglycones) or as glycosides.  Isomers.  Anthrone: Parent structure (pale yellow, non- soluble in alkali, non-fluorescent)  Anthronol: brown-yellow, soluble in alkali, strongly fluorescent  Anthronol derivatives (e.g. in Aloe – have similar properties – fluorescence used for identification)
  30. 30. 30 Oxanthrones  Found in Cascara bark  Intermediate products (between anthraquinones and anthranols)  When oxidised oxanthrones it form anthraquinones  Oxanthrones are detected by Modified Borntrager’sTest (oxanthrones oxidised using hydrogen peroxide) oxanthrone
  31. 31. Dianthrones  Derived from 2 anthrone molecules  2 molecules may/not be identical  Dianthrones are form easily due to mild oxidation of anthrones  It form important aglycones  Cassia  Rheum 31
  32. 32. 32
  33. 33. 33 General structure of glycoside Structure-Activity Relationship
  34. 34. 34  Glycosylation is essential for activity.  Hydroxylation at C-1 and C-8 is essential for activity.  Oxidation level at C-9 and C-10 is important:  Highest level of oxidation (anthraquinones) have the lowest activity.  Oxanthrones are less active than anthrones.  Complete reduction of C-9 and C-10 eliminates the activity.  Substitution at C-3 have great impact on activity: CH2OH > CH3 > COOH
  35. 35. 35 Mechanism of Action:  The glycosides are absorbed from the small intestine and re-excreted in the large intestine where they increase the motility so produce laxation.  Aglycones produce griping effect so it is recommended to prescripe antispasmodic with them.
  36. 36. 36 Mechanism of action  Molecules have to possess certain features for activity: [1] glycosides [2] carbonyl keto function on centre ring [3] 1,-8- positions have to have –OH  Potency:  anthrone > anthraquinone> dianthrone  Aglycones not therapeutically active in animals , lipid soluble absorbed in stomach and never reach colon to produce a local effect.
  37. 37. 37  Highly active phenolic group irritant to mucosa  Glycosides very water soluble – reach large intestine where they are hydrolysed by E.coli enzymes and become lipid soluble and absorbed into circulation.  5-8 hours to act  take night before  in low doses – drug metabolised by liver and recirculated via bile to give more effect  people especially elderly can become reliant on them needing higher dose to produce an effect  carcinogenic to melanosis coli
  38. 38. Senna - Leguminosae  Definition: Consists of the dried leaflets of Cassia senna (Alexandrian senna), or Cassia angustifolia (Tinnevelly senna). 38
  39. 39. Cassia - Senna  Indigenous to Africa (tropical regions)  Used since 9th and 10th century  Itroduced into medicine byArab physicians (used both the leaves and pods)  Exported by Alexandria – name of the Sudanese drug. 39
  40. 40. Senna - Collection  Collected in September  Whole branches bearing leaves are dried in the sun.  Pods and large stalks are separated with sieves.  Leaves are graded (whole leaves and half- leave mix, siftings).  Whole leaves – sold to public  Rest – used for galenicals. 40
  41. 41. 41 Senna - Constituents  Senna consist four types of glycosides: Sennoside A Sennoside B Sennoside C Sennoside D In their active costituents are sennoside A, sennosides B  Upon hydrolysis of sennosides it gives two molecules glucose+aglycones: Sennidin A and Sennidin B.  Sennoside C & Sennoside D  Rhein  Aloe-emodin  Palmidin A (Rhubarb)
  42. 42. 42
  43. 43. Senna - Constituents  Kaempferol (yellow flavanol) + glucoside (kaempferin)  Mucilage  Calcium oxalates  Resin 43
  44. 44. Comparison of Alexandrian and Tinnevelly Senna  Macroscopical  Seldom larger than 4 cm in length  Grey-green  Asymmetric at base  Broken and curled at edges  Few press markings  Macroscopical  Seldom exceeds 5cm in length  Yellow-green  Less asymmetric at base  Seldom broken and normally flat  Often shows impressions (mid vein) 44
  45. 45. Comparison between Alexandrian and Tinnevelly Senna  Microscopical  Hairs – numerous (approximately three epidermal cells apart)  Most stomata have two subsidiary cells  Microscopical  Hairs less numerous (approximately six epidermal cells apart)  Stomata have 2-3 subsidiary cells with the respective ratio 7:3 45
  46. 46. Comparison between Alexandrian and Tinnevelly Senna  ChemicalTests  Ether extract of hydrolysed acid solution of herb with methanolic magnesioum acetate solution gives  Pink colour in daylight  Pale green-orange colour in filtered UV light TLC  Hydroxymusizin glycoside present  ChemicalTests  SameTest  Orange colour in daylight  Yellow-green colour in filtered UV light TLC  Tinnevellin glycoside 46
  47. 47. Senna – Allied Drugs & Substitutes Allied drugs  Bombay, Mecca and Arabian Sennas (found in Cassia angustifolia from Arabia).  Dog senna – Cassia obovata  Cassia auriculata – Indian Senna  Cassia podocarpa  Substitutes or Adulterants  Argel leaves – Solenostemma argel  Coriario myrtifolia 47
  48. 48. Senna Fruit  Definition: Senna pods are the dried, ripe fruits of Cassia senna and Cassia angustifolia, which are commercially known as Alexandrian and Tinnevelly senna pods respectively. Both have separate monographs 48
  49. 49. Senna Fruit - Collection  Pods are collected with the leaves and dried in a similar fashion.  After separation of the leaves, the pods are hand-picked into various qualities, the finer being sold (commercially), while the finer pieces are used to make galenicals. 49
  50. 50. Senna Fruit - Constituents  Active constituents are found in the pericarp.  Similar to those actives of the leaves  Sennoside A  Sennidin 50
  51. 51. 51 Senna - Uses  Laxatives (habitual constipation or occasional use).  Lacks astringent after-effect (Rhubarb)
  52. 52. Senna –Additional uses  Medicinal Actions  Vermifuge, diuretic, febrifuge  Other uses: laxative candy (bitter taste).  Also used to treat flatulence, gout, fever.  Topically: poultice prepared with vinegar to treat pimples.  NOTE: Senna may cause urine to become reddish – no clinical significance. Contra-indications  Gout, colitis, GI inflammation.  Should not be used with cardiac glycosides.  Seeds/pods give gentler action than leaves: more appropriate for the young, elderly and those prone to stomach cramps.  NB: Over-use causes dependency.  Overdose: nausea, bloody diarrhoea, vomiting and nephritis.  Long-term use: dehydration & electrolyte depletion, worsening constipation and weakening intestinal muscles. 52
  53. 53. Cascara Bark- Rhamnaceae  Definition: Official cascara sagrada is the dried bark of Rhamnus purshianus. Bark is collected from wild trees (depletion is leading to the increase of cultivation) 53
  54. 54. Rhamnus purhsianus - Cascara  Etymology  Rhamnos – Greek, branch, shiny shrub. Purshiana after Pursh, botanist 1st described herb in 1814  Other Common Names  Bearwood, bitterbark, buckth orn, coffeeberry, mountain cranberry, persiana, sacred bark. 54
  55. 55. Cascara Bark - History  Recently introduced to Modern Medicine.  Known to early Mexican and Spanish priests.  Not introduced to medicine until 1877. 55
  56. 56. Cascara – Collection & Preparation Collected form mid-April to end ofAugust, when it separates readily from the rest of the trunk.  Longitudinal incisions are made 10cm apart and the bark removed.  Tree is then usually felled and the branch bark separated.  Bark is then dried in the shade with the cork facing upwards. This is referred to as ‘natural’ cascara. Commercial supplies are comminuted to give small, even fragments called ‘evenized’, ‘processed’, or ‘compact’ cascara. 56
  57. 57. 57 Cascara Bark - Storage  During preparation and storage the bark should be protected from rain and damp (partial extraction of constituents may occur or bark may become mouldy).  Should be stored for at least 1 year before use .  Bark appears to increase in medicinal value up unto its 4 years old (stored bark)
  58. 58. Cascara Bark – Why Stored for a Year?  When stored for at least a year – better tolerated by patient (less griping pains due to increased peristalsis)  Yet as effective as fresh bark.  Reason?  Due to Hydrolysis and other changes that occur during storage.  Bitter taste of Cascara can also be reduced by treating the bark with alkali (alkali earths or MgO). 58
  59. 59. 59 Cascara Bark – Constituents  Four main glycosides – Called Cascarosides  CascarosideA  Cascaroside B  CascarosideC  Cascaroside D
  60. 60. 60 Cascara Bark – Constituents  Two aloins:  C – Glycosides  Breakdown products of CascarosidesA-D  Barbaloin (derived from aloe-emodin)  Chrysaloin (derived from chrysopanol anthrone)
  61. 61. 61 Cascara Bark – Constituents  O-glycosides  Derived from  Emodin  Emodin oxanthrone  Aloe emodin  chrysophanol
  62. 62. 62 Cascara Bark – Constituents  Dianthrones  Emodin  Aloe-emodin  Chrysophanol  Hetrodianthrones  Palmidin A, B and C (Rhubarb)
  63. 63. 63 Cascara Bark - Substitutes  Rhamnus alnifolia (too rare)  Rhamnus crocea (bark is very different from official drug)  Rhamnus californica (so closely related to Rhamnus purshianus some botanists do not consider them to be separate species).  Rhamnus fallax
  64. 64. 64 Cascara Bark - Uses  Purgative  Similar to Senna  Normally as a tablet  Also used on animals
  65. 65. Cascara Bark –Additional uses  Physiological Action  Astringent (bark – tannins), bitter tonic, chologogue, emetic, he patic, stomachic.  Medicinal Uses Move stagnation, clear heat. The most widely used laxative world-wide. Topically: Used as a wash for herpes lesions  Excessive use: nausea, vomiting, heamato rrhoea. Long term use: Weakens intestinal muscles.  Contra-indications: children younger than 14, during pregnancy, lactation, IBS, C rohn’s, intestinal obstruction, and idiopathic abdominal pain. 65
  66. 66. Rhubarb - Polygonaceae  Definition: Rhubarb/Chinese Rhubarb is the rhizome of Rheum palmatum. Other species and hybrids of Rheum, except R. rhaponticum, may also be included. 66
  67. 67. Chinese Rhubarb - History  Chinese Rhubarb has a long history.  Mentioned in a herbal of 2700BC.  Formed an important article of commerce on the Chinese trade routes to Europe.  Still used medicinally today. 67
  68. 68. Chinese Rhubarb – Collection & Preparation  Rhizomes are grown at high altitudes (+3000m).  Collected in Autumn or spring (6-10yrs old)  Cork is removed, cut.  Artificially dried.  Packed in tin-lined wooden cases.  Inferior quality herbs are packed in hessian bags 68
  69. 69. Chinese Rhubarb - Constituents 1. Anthraquinones without a carboxyl group – chrysophanol, emodin, al oe-emodin & physcion. Also the glycosides of these substances. 2. Anthraquinones with a carboxyl group (rhein and its glycoside: glucorhein). 69
  70. 70. Chinese Rhubarb - Constituents 3. Anthrones and dianthrones of chrysophanol, emodi n, aloe-emodin or physcoin. 4. Dianthrone glucosides of rhein (Sennosides A and B). 5. Hetrodianthrones derived from 2 different anthrone molecules: Palmidin A and Palmidin B. 70
  71. 71. Chinese Rhubarb - Constituents  Free anthraquinones: chrysophanol, emodin, aloe-emodin and rhein.  Some of the above constituents may also occur as glycosides. 71
  72. 72. Chinese Rhubarb - Uses • Bitter stomachic • Diarrhoea (low doses) – contains tannins • Purgative (high doses) – followed by an astringent effect. • Suitable only for occasional for occasional use, not for chronic constipation. 72
  73. 73. Rhubarb – Additional Uses  Etymology  Rheo – Greek, ‘to flow’, in reference to the purgative properties.  Medicinal Actions  Anti-helminthic, anti- bacterial, anti- inflammatory, antiseptic, astr ingent (low doses), sialagoge, vulnerary  Topical Uses:  Poultice to treat boils, burns, wounds. Used to stop bleeding (tannins – stypic and astringent). Used as a mouthwash for oral ulcers.  Other uses: Acid content: fresh root can be used to polish brass.  Caution  Leaves should be avoided – high calcium oxalate - toxic 73
  74. 74. Aloe - Liliaceae  Definition: Aloes are the solid residue obtained by evaporating the liquid which drains from the transversely cut leaves of various Aloe species.  The juice is usually concentrated by boiling and solidifies on cooling.  Official varieties are the Cape Aloes from SA and Kenya (Aloe ferox), and the Curacao Aloes from West Indies (Aloe barbadensis). 74
  75. 75. 75 Preparation of Cape Aloes  Cape Aloes are prepared from the wild plants of Aloe ferox.  Leaves are cut transversely near the base.  Two hundred leaves arranged around a shallow hole in the ground (lined with canvas or goatskin).  Cut ends overlap & drain into the canvas. After 6hrs all the juice is collected.  Transferred to a drum.  Boiled for 4hrs on an open fire.  Poured into tins while hot  solidifies.
  76. 76. Preparation of Cape Aloes 76
  77. 77. Cape Aloes - Characteristics  Dark brown or Green- brown  Glassy masses  Thin fragments have a deep olive colour Semi-transparent. 77
  78. 78. Cape Aloes - Characteristics  Powder: green-yellow  When rubbed two pieces of drug together – powder is found on the surfaces.  Characteristic sour odour (rhubarb/apple-tart odour).  Taste: nauseous and bitter.  Microscopy: powder in lactophenol – amorphous. 78
  79. 79. Characteristics of CuracaoAloes  Colour: yellow-brown – chocolate brown.  Poor qualities (overheated) black colour.  Opaque  Breaks with a waxy facture  Semi-transparent  More opaque on keeping.  Nauseous and bitter taste.  Characteristic iodoform odour.  Microscopy: lactophenol – acicular crystals 79
  80. 80. Aloes - Constituents  C-glycosides  Resins  Glycosides  Aloin  Barbaloin  Isobarbaloin  Aloe-emodin Cape Aloes: Also Contain Aloinoside A & Aloinoside B (O-glycosides of barbaloin) 80
  81. 81. 81 Aloe - Constituents
  82. 82. Aloe Constituents & Chemical Tests:  Unlike C-glycosides, O-glycosides of Aloe are not hydrolysed by heating with dilute acids or alkali.  Can be decomposed with ferric chloride & dilute HCl - NB: Modified Borntrager’sTest – oxidative hydrolysis. Anthraquinones give a red colour when shaken with dilute ammonia.  NB: All Aloes give a strong green fluorescence with borax (characteristic of anthranols) - General test for aloes. 82
  83. 83. Aloe - Uses  Purgative  Seldom prescribed alone – activity is increased when administered with small quantities of soap or alkaline salts; Carminatives moderate griping tendency.  Ingredient in Friar’s Balsam. 83
  84. 84. Aloe – Additional uses  Medicinal Uses:  Anti-bacterial, anti- fungal, chologoge, emmenog ogue, anti-inflammatory (juice), anti-inflammatory , demulcent, vulnerary, immu ne-stimulating (gel). Radiation burns (internal and external use)  Contra-indications Pregnancy & lactation (internal uses)  Etymology  Name derives from Arabic alu, meaning shiny or bitter in reference to the gel.  Other uses  Khoi-San hunters rub gel on their bodies to reduce sweating and mask their scent.  Used to break nail-biting habit. 84
  85. 85. Aloe vera Products  These are derived from the mucilage gel – parenchyma cells  Should not be confused with aloes (juice of pericycle – juice used for laxative effect).  Cosmetic industry (usefulness often exaggerated) - Used as suntan lotions, tonics and food additives.  Mucilage = polysaccharide of glucomannans and pectin 85
  86. 86. Cochineal  Definition: Cochineal is the dried female insect, Dactylopius coccus, containing eggs and larvae.  Insects are indigenous to Central America, commercial supplies are derived from Peru. 86
  87. 87. Cochineal  Eggs are protected during the rainy season are ‘sown’ on cacti – on which it is intended to breed.  Both male and females arise. After a time, fecundation occurs. Females attach themselves to the cacti and the males die out.  Females swell to x2 their original size due to developing larvae & develop red colouring matter. 87
  88. 88. 88 Cochineal  Larvae mature after 14days and escape from the now dead body of the parent.  Only a small portion develop into males.  For next 2 weeks, males fly and young females crawl on the plant.  Life cycle = 6 weeks.  3-5 generations may be produced in 1 season
  89. 89. 89 Cochineal - Collection  Insects are brushed from plants with small brooms and killed (some left to provide for subsequent crops).  First crop killed contains the most colouring matter.  Insects are killed by plunging them in boiling water, stove heat or exposure to fumes by burning sulphur or charcoal.  If heat is used – insects change to purple – black – called ‘black grain’.  Fume killed – turn purple-grey called ‘silver grain’.  Small immature insects and larvae which can be separated by sieves are sold as ‘granilla’ or siftings.
  90. 90. 90 Cochineal Collection
  91. 91. Cochineal - Characteristics  Oval in shape Half cm in length  Examined microscopically after removing the colouring matter (ammonia solution).  Each insect contains 60 to 450 eggs and larvae. 91
  92. 92. 92 Cochineal - Constituents  C-glycoside example anthraquinone derivative is bright purple, water-soluble colouring matter  Carminic acid  Fat  Wax  Adulteration: occurs by increasing the weight of the insects by ‘dressing’ it with inorganic matter in a colour which blends in with that of the insect.  Detected when insects are placed in water
  93. 93. 93 Chemical test Borntrager’s and Modified Borntrager’s test:  For Aglycones:  Extract plant material with organic solvent.  Shake with NH4OH OR KOH.  For O-Glycosides:  Boil plant material with dil. HCl for 10 min, filter and shake with organic solvent (Ether or Benzene).  Separate the organic solvent.  Shake with NH4OH OR KOH.  For C-Glycosides:  Boil plant material with dil. HCl/FeCl3, filter and shake with organic solvent (Ether or Benzene).  Separate the organic solvent.  Shake with NH4OH OR KOH.  Positive result indicated by Rose Red colour in the aqueous alkaline layer.