INTRODUCTION:

Dioscorea bulbifera is a tribal plant, which belongs to the family Dioscoreaceae assigned to the order dioscorales. It is a climber plant with tuberous root. Dioscorea is a large genus of annual twinning herbs, distributed throughout the moist tropics of the world, which extends into warm temperate regions. It is commonly known as air potato, air yam or bulbil-bearing yam [1]. In India it is known as Gonth, Kolkand, Varaheekand. It is a climber plant with tuberous root [2]. The tuber is edible when either boiled or cooked [3,4]. One teaspoon of tuber powder and water taken in orally is a single dose cures for abdominal [5]. Traditionally Dioscorea bulbifera have been used to lower glycemic index, therefore it provides better protection against diabetes and obesity [6]. In traditional Indian and Chinese medicine it is widely used in the treatment of sore throat, goiter, gastric cancer and carcinoma of rectum [7,8].

Received on 30.04.2015 Modified on 11.05.2015

Research J. Pharm. and Tech. 8(8): August, 2015; Page 1059-1062

DOI: 10.5958/0974-360X.2015.00182.1

In places like Cameroon and Madagascar the bulbs are pounded and applied to abscesses, boils and wound infections [9]. In India the bulbs are used to treat piles, dysentery, and are applied to ulcers, pain, and inflammation [10]. This tuber contains the plant reserves, mainly starch, and it is often incorporated in the human diet. The tuber not only stores food but also many of the plants as secondary metabolites, which are commonly referred to as anti-nutritional factors [11].

Classification:

Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Monocots
Order:	Dioscoreales
Family:	Dioscoreaceae
Genus:	Dioscorea
Species:	D. bulbifera

Distribution:

It is native to tropical Asia and sub-Saharan Africa, air potato was introduced by ancient Polynesians throughout much of the South Pacific where it is now considered invasive. It was brought to the Americas from Africa during the slave trade [22] and brought to Florida in 1905 [23]. It is found throughout the state from Escambia Country in Panhandle to the Florida Keys.

Air potato is a member of the yam family. Yams are cultivated for their edible underground tubers in western Africa, where they are important commodities. However, uncultivated species- such as air potato- are generally bitter and even poisonous [24]. About 50 species of Dioscorea are found in India. A large number among them occur in the wild state. Dioscorea species are distributed in nearly throughout India except in the dry north-western regions. They are found growing at elevations of 8000-15000 ft. in Himalayas. In its wild state, it is extremely bitter. Under cultivation the plant loses its bitterness and is much grown for the tubers, which are roasted and eaten. The tuber is used by the tribal population of central India as a food particularly in Madhya Pradesh, Chattisgurh, Jharkhand and Orissa [2].

Descriptive:

Air potatoes are vigorously twinning herbaceous vine, often arising from an underground tuber. Freely branching stems grow to 60 ft. in length. Stems are round or slightly angled in cross-section and twined to the left [25]. Air potato can grow extremely quickly, roughly 8 inches per day. It typically climbs to the tops of trees and has a tendency to take over native plants. New plants develop from bulbils that form on the plant, and these bulbils serve as a means of dispersal. The aerial stems of air potato die back in winter, but resprouting occurs from bulbils and underground tubers. The primary means of spread and reproduction are via bulbils. The smallest bulbils make control of air potato difficult due to their ability to sprout at a very small stage [26].

Phytochemical constituents:

When subjected to phytochemical screening, the presence of flavonoids,saponins, cardiac glycosides and terpenoids in methanol extracts. High flavonoids and terpenoids was also found in other species of D.bulbifera. Cholesterol and alkaloid have not been detected in most studies [11]. Yams have been well respected by the herbalist community for generations due to the presence of steroidal drug, i.e., diosgenin. It is used as a precursor for the synthesis of hormones and corticosteroids which improve fertility in males [12,13]. Saponins have a natural tendency to ward off microbes which makes them a good candidate for treatment of fungal and yeast infections. These compounds serve as natural antibiotics, which help the body to fight infections and microbial invasion [14]. Cardiac glycosides have been used as stimulant in case of cardiac failure[15,16]. Phenolic content were found to be significantly high in methanolic extracts [17].

Free radical scavenging and anti-oxidant properties:

Free radicals are the spontaneous byproducts in biochemical systems during metabolic processes that can cause extensive damage to tissues and biomolecules leading to various severe clinical implications particularly diabetes mellitus, chronic inflammation, neurodegenerative disorders and cancer [18,19]. Consumption of natural antioxidants from food supplements and traditional medicines constitute an alternative solution to the problem. Phenolic and flavonoid compounds are reported to possess both potent antidiabetic and free radical scavenging activity [20].

Present studies reveal that hydro alcohol extracts of Dioscorea bulbifera tubers contains carbohydrates, glycoside, alkaloids and proteins and its physicochemical analysis (ash values and extractive values) shows the presence of foreign particles as mentioned in pharmacopoeia [21].

Analgesic and anti-inflammatory properties:

Aqueous and methanol extracts from the bulbils of Dioscorea bulbifera var Sativa have a potent antinociceptive effect against chemical pains provoked by acetic acid or formalin and a slight activity against mechanic pain induced by pressure. These extracts also present important anti- inflammatory effects on acute edema induced by formalin. The acetic acid-induced abdominal constriction method is widely used for the evaluation of peripheral antinociceptive activity [27] because it is very sensitive and able to detect antinociceptive effects of compounds at dose levels that may appear inactive in other methods [28,29]. Local peritoneal receptors are postulated to be partly involved in the abdominal constriction response [30]. In the formalin tests, there is a distinctive biphasic nociceptive response termed early and late phases. Drugs that act primarily on the central nervous system inhibit both phases equally while peripherally acting drugs inhibit the late phase [31, 32]. The early phase is probably a direct result of stimulation of nociceptors and reflects centrally mediated pain while the late phase is due to inflammation with a release of serotonin, histamine, bradykinin and prostaglandins [33] and at least to some extent, the sensitization of central nociceptive neurons [33,34,35]. Suppression of both phases of pain was observed in animals with aqueous and methanol extracts. These results lend strong credence to the presence of both central and peripheral affects. Since D. bulbifera extracts are very efficient on visceral pain induced by acetic acid and on late phase of pain induced by formalin all mediated by histamine, serotonin, bradykinin and prostaglandins, it is possible that these extracts possess anti-inflammatory activities[36].

Gastroprotective properties:

Dioscorea bulbifera extracts have been proven to show gastroprotective function, by protecting gastric damages caused by indomethacin casued in wistar albino rats [21]. This indicates that D. bulbifera showed potent gastroprotective effect against NSAIDs induced gastric damage at all doses.

Anti-Bacterial activity:

The research in anti-microbial assay of six compounds isolated Dioscorea bulbifera is resistant against Mycobacterium and gram negative bacteria and among six three was considered as potential antimicrobial drugs to fight against MDR bacteria.[37]

CONCLUSION:

Research has shown that the air potato contains flavonoids, saponins, cardiac glycosides and terpenoids in methanol extracts. It is shown to lower the glycemic index hence possess potent anti-diabetic properties. They show free radical scavenging and anti-oxidant activity therefore the air potato serves as a source of natural anti-oxidant as an alternative. It shows potent antinociceptive effect against pains induced by aceticacid, formalin and pressure. Since oxidative stress is a key player in several diseases such as cancer, diabetes mellitus, artherosclerosis, cardiovascular diseases, ageing and inflammatory diseases, results from an imbalance between formation and neutralization of prooxidants. It shows high gastroprotective as well antimicrobial properties. The Dioscoreacea family is of high medicinal importance in both edible and extract forms.

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