This document discusses Dioscorea, a genus of plants also known as yams. It provides information on the biological source, cultivation, morphology, microscopy, chemical constituents, therapeutic uses, and marketed products of Dioscorea. Specifically, it notes that Dioscorea is the dried rhizome of various Dioscorea species native to regions including North America, Mexico, India, Nepal and China. Microscopically, Dioscorea has cortical parenchyma tissue and collateral vascular bundles. Its main chemical constituent is diosgenin, a steroidal sapogenin. Therapeutically, Dioscorea is used to manufacture progesterone and steroid drugs to treat disorders of the genitary organs as

1. Pharmacognosy and
Phytochemistry –II (BP504T)
Institute of Pharmaceutical
Research,
GLA University, Mathura
Dioscorea

2. Objective of the class
Dioscorea
Biological source
Cultivation and collection
Morphology
Microscopy
Chemical constituent
Therapeutic uses
Marketed products
Sonia Singh, Assistant Professor, GLA University, Mathura
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3. Dioscorea
Synonym
Yam
Biological source
Dioscorea is the dried rhizome of several species of Dioscorea
like D. villosa, D. prazeri Prain and Burk; D. composite; D.
spiculiflora; D. deltoidea and D. floribunda, belonging to family
Dioscoreaceae
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4. It is mainly found in North America, Mexico, India (Himalayas from
Kashmir and Punjab up to an altitude of 3,000 m), Nepal and China.
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5. Cultivation and Collection
 It is a perennial climber growing to 3 m. The plant prefers sandy,
loamy and clay soils and requires well-drained soil.
 The plant prefers acid, neutral and basic (alkaline) soils. It can grow
in semishade or no shade. It requires moist soil.
 It can be cultivated in three methods, by sowing seeds or stem
cuttings or by tubercles.
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6.  Seeds are sown in the month of March to April in a sunny position in a
warm green house and only just covered.
 It germinates in one to three weeks at 20°C. The seedlings are taken out
as soon as they are large enough to handle and grown on in a green house
for their first year.
 Transplanted in late spring as the plant comes into new growth. Basal
stem cuttings are done in the summer.
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7.  Tubercles (baby tubers) are formed in the leaf axils. These are
harvested in late summer and early autumn when about the size of
a pea and coming away easily from the plant.
 They should be potted up immediately in individual pots in a
greenhouse or cold frame and transplanted out in early summer
when in active growth.
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8. Morphological study
 Colour : Slightly brown
 Odour : Odourless
 Taste : Bitter and acrid
 Size : Varies depending on the actual age of the rhizomes (tubers)
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9. Dioscorea
species
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10. Sonia Singh, Assistant Professor, GLA University, Mathura
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11. Microscopical study
 Absence of epidermis, the cork is made up of few layers and next
to cork.
 It has cortical parenchymatous tissue with thin wall.
 The major part of the drug is occupied by stele and consists of
collateral type of fibrovascular bundles.
 The drug has indistinguishable endodermis and pericycle.
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12. Microscopy of
Dioscorea
tubers
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13. Chemical constituents
 The roots contain diosgenin (4–6%) a steroidal sapogenin and its
glycoside smilagenin, epismilagenin and beta isomer yammogenin.
 It also contains sapogenase (enzyme), phenolic compounds and
starch (75%).
 Non edible as bitter in taste .
 Tubers rich in glycosides and phenolic compounds.
 Diosgenin on hydrolysis yield Dioscin.
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14. Dioscin
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15. Therapeutic uses
 It is a main source of diosgenin.
 Widely used in modern medicine in order to manufacture
progesterone and other steroid drugs.
 Used as contraceptives and in the treatment of various disorders of
the genitary organs as well as in a host of other diseases such as
asthma and arthritis.
 It is also used in rheumatism.
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19. It is one of the ingredients of the preparations known as Explode (Herbotech Pharmaceuticals).
Marketed products
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