Dioscorea Bulbiferea L A Natural Treasure Prove Pharmacognosy, Phytochemistry and Pharmacology -Unveiled

Tribal plants like Dioscorea bulbifera are members of the Dioscoreaceae family, which is a subfamily of the Dioscorales order. It is a tuberous-rooted climber plant. Dioscorea is a vast genus of annual twinning herbs that grow over the world's moist tropics and into warm temperate zones. It is commonly known as air potato, air yam or bulbil-bearing yam [1]. In India it is known as kodi kizhangu, 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]. Dioscorea bulbifera has historically been used to reduce glycemic index, which improves protection against obesity and diabetes. [6]. It is frequently used in traditional Chinese and Indian medicine to treat cancer, goiter, sore throats, and rectum carcinoma. 7,8]. 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].

Taxonomic Classification [12]

Kingdom:  Plantae

Superdivision: Streptophyta

Division:  Tracheophyta

Class:  Magnoliopsida

Superorder:  Lilinanae

Order:  Dioscoreates

Family:   Dioscoreaceae

Genus: Dioscorea L.

Species:  Dioscorea bulbifera Linn

Vernacular Names [13,14]

Tamil: Kodikilanga, Kaattu-k-kaay-valli

English: Potato Yam, Air potato

Hindi: Varahi kanda, Kadu Kanda, Ratalu

Gujarati: Dukkarkanda

Bengali: Ratalu, Ban Alu

Marathi: Manakund, Kadu-karanda, Varahi

Kannada: Kuntagenasu

Konkani: Karamdo

Malayalam: Pannikizhangu, Kattukachil

Oriya: Pita Alu

Telugu: Adavi Dumpa

Macroscopical analysis / morphological description [6].

Microscopic Evaluation of Dioscorea bulbifera

Tuber Tissues:

The microscopic structure of the tuber itself provides insights into its development and evolutionary history.

Periderm: A well-developed periderm (outer bark) is characteristic and its thickness and structure can be influenced by environmental factors and evolutionary adaptation

Vascular Bundles: The arrangement and structure of the vascular bundles within the tuber tissue are important for nutrient and water transport and can show variations that contribute to evolutionary studies.

Parenchymatous Tissue: The cortical parenchyma, which makes up a significant portion of the tuber, also plays a role in storage and can exhibit differences in structure that are relevant to its evolutionary path.

Starch Grains: Found in both the cortex and ground tissues, these are simple, solitary, or in groups, typically rounded to oval, with a distinctive triangular shape.

O They measure 11–28 µm in diameter.

O A hilum (a point where growth began) is present at the narrower end.

O A high percentage of these granules (98%) are triangular, with many exhibiting longitudinal fissures and curved forms.

Chemical composition and phytochemical analysis.

The rhizomes of Dioscorea are 75% starch. Their extremely bitter flavour renders them inedible. The primary components of dioscorea are the steroidal sapogenin diosgenin (4–6%) and its glycosides, β-isomer yammogenin and smilagenin. The sapogenase enzyme is also found in rhizomes. Moreover, tubers are abundant in phenolic and        glycoside chemicals. Saponin dioscin hydrolyses to produce diosgenin [8]. " Two components make up dioscin. One molecule of D. glucose and two molecules of L-rhamnose are present. One molecule of L-rhamnose and two molecules of D. glucose are present in gracillin [9]. In 1985, Ozo et al. [10] identified the procyanidin dimmers B-1 and B-3 as well as the flavonoid component Cyanidin-3-glucoside in Dioscorea alata L. According to a publication, Dioscorea also includes dioscorins that have the ability to inhibit trypsin and carbonic anahydrase [11]. Report the existence of saponins, alkaloids, flavonoids, tannin, and phenols in Dioscorea. belophylla [12]. Also Yoon et al [13] in 2008 reported Allantoin, in Dioscorea rhizome.

Phytochemicals present in D. bulbifera and their biological activities.

Chemical structures of few important phytochemicals found in Dioscorea bulbifera:

Ethnobotanical uses of D. bulbifera

Throughout history, medicinal plants have always been considered a treasure. serves as a symbol of traditional medicine and cru for the majority of humanity. They now serve as the primary source for the production of pharmaceutical medications as well. For millennia, different plant parts have been utilised to treat a variety of illnesses. Dioscorea is a lengthy genus with possible ethnomedical uses and scores several The Tropics have seen the realisation of numerous medical applications of research (Girach et al., 1999; Tiwari and Pande, 2006; Mishra et al., 2008; Sharma and Bastikotti, 2009; Teron, 2011; Dutta, 2015). D. bulbifera is the Dioscorea species that has been used the most in traditional medicine to treat a wide range of conditions. Due to its numerous ethnomedical applications, D. bulbifera has drawn increased interest in the last 20 years. It is renowned for being bitter and salty.
Therefore, D. bulbifera has been used traditionally to treat dandruff, skin infections, piles, throat infections, haemoptysis, pharyngitis, cough, and epistaxis. Furthermore, it is utilised in Chinese traditional medicine to treat a number of ailments, including cancer, detoxification, clotting blood to stop bleeding, and removal of harmful heat (Editorial Board of Chinese Medical Sciences, 1999). As a vegetable, tubers are roasted and boiled to treat syphilis, leprosy, piles, ulcers, cough, and dysentery (Dutta, 2015). The locals in Uganda boil and consume D. bulbifera tubers to treat HIV patients (Nabatanzi, 2016). Bulbul in the Republic of Congo, raw According to Terashima et al. (1985), D. bulbifera is used to treat ringworm. D. bulbifera has been used to treat TB, diarrhoea, struma, dysentery, and throat infections in the Indian traditional medical system. The Indian tribal inhabitants of the Satpuda Hills use it as an antihel-minthic. D. bulbifera tuber is used orally by the Bhoxa community in Dehradun, Uttarakhand, to treat dysentery and diarrhoea. To treat coughs, D. bulbi's roasted and crushed tubers are taken orally with salt. To get rid of dandruff from hair, its twigs and young shoots are crushed and applied. In traditional medicine, D. bulbifera leaves are also used to treat skin conditions. The tubers are also consumed to increase appetite.

Ethnobotanical uses of D. bulbifera.

Pharmacological Activities:

Anti-diabetic activity

Type II diabetes has been characterized by post prandial increase of blood glucose. This post prandial increase can be reduced by inhibiting the activity of α-amylase and α-glucosidase which are involved in carbohydrate digestion. D. bulbifera crude extracts significantly inhibits α-amylase and trypsin (13.2 ± 2% and 4.3± 0.2%) (Bhandari and Kawabata, 2004). The aqueous extracts of D. bulbifera tubers had also exhibited antihyperglycemic activity in C57BL/6J mice and streptozotocin (STZ) treated Wistar rats (Ahmad et al., 2009). D. bulbifera extracts at 500 mg/kg of doses to STZ treated Wistar rats resulted remarkable antihyperglycemic effects after six weeks of treatment. Different solvent (ethyl acetate, methanol, petroleum ether and 70% ethanol) extracts of D. bulbifera were tested against anti-diabetic effects and interestingly, ethyl acetate extract was found to be optimum by inhibiting α-glucosidase by 99.6% and α-amylase by 73.39% (Ghosh et al., 2012). In another study by Ghosh and co-workers (2014) proved that diosgenin from D. bulbifera developed as a novel drug against type II diabetes. Ethyl acetate extracts of D. bulbifera with diosgenin content exhibited highest inhibition upto 82.64 ± 2.32% and 72.06 ± 0.51% against α-glucosidase and α-amylase (Ghosh et al., 2014).

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 [18] because it is very sensitive and able to detect antinociceptive effects of compounds at dose levels that may appear inactive in other methods [19,20]. Local peritoneal receptors are postulated to be partly involved in the abdominal constriction response   [21]. 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 [22, 23]. 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 [24] and at least to some extent, the sensitization of central nociceptive neurons [25,26,]. 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[27].

Antimicrobial Activity

Each D. bulbifera ethyl acetate extract demonstrated a moderate level of antibacterial activity in inhibiting bacteria obtained from animals and poultry using the disc method. When compared to other extracts, the acetone extract had the strongest antibacterial action(28). When examined utilising the disc-diffusion method of antimicrobial testing, an ethanol extract of D. bulbifera shown a strong antibacterial impact against S. aureus and Candida albicans, whereas an aqueous extract demonstrated higher antibacterial activity against E. coli (29,30). Using the broth microdilution method and the microplate alamar blue assay, the antimicrobial activities of the methanol extract, fractions (DBB1 and DBB2), and six compounds isolated from the bulbils of D. bulbifera—bafoudiosbulbins A (1), B (2), C (3), F (4), G (5), and 2,7-dihydroxy-4-methoxyphenanthrene (6)—against Mycobacteria and gram-negative bacteria involving multidrug resistant (MDR) phenotypes expressing active efflux pumps were tested. The majority of the examined bacteria belonging to MDR phenotypes, including E. coli AG102, P. aeruginosa PA124, E. aerogenes CM64, and K. pneumoniae KP55 and KP63, showed positive activity when exposed to the crude extract, fractions, and compound 3 [30]. Significant activity was demonstrated by two clerodane diterpenoids, Bafoudiosbulbins A and B, against P. aeruginosa, S. typhi, S. paratyphi A, and S. paratyphi B.(31). There was broad-spectrum plasmid-curing efficacy of 8-epidiosbulbin E acetate against MDR bacteria, including Vancomycin-resistant enterococci (VRE). Shigella sonnei, P. aeruginosa, E. coli, Enterococcus faecalis, and Bacillus subtilis were among the clinical isolates from which it cured antibiotic-resistant plasmids with a 12–48% curative efficiency(32). Vanillic acid and isovanillic acid also demonstrated antibacterial properties(33) In vitro antibacterial activity was examined in the successive extracts of Dioscorea bulbifera bulbils. Significant action against A. fumigatus and R. nigricans was demonstrated by the petroleum ether and chloroform extracts out of all the extracts. The extracts of distilled water and petroleum ether demonstrated good efficacy against K. pneumoniae. The extract of chloroform had weak efficacy against S. aureus.(33). Silver nanoparticles of D. bulbifera tuber extract shown a synergistic impact with beta-lactam (piperacillin) and macrolide (erythromycin) antibiotics against multidrug-resistant Acinetobacter baumannii. When combined with silver nanoparticles of D. bulbifera tuber extract, chloramphenicol or vancomycin also shown a synergistic impact against Pseudomonas aeruginosa. Strong evidence of the synergistic activity of streptomycin and silver nanoparticles against E. coli was found.(34)

Anticancer activity

The authors used a medicinal plant called Dioscorea bulbifera tuber extract (DBTE) to create new platinum–palladium bimetallic nanoparticles (Pt–PdNPs). Monodispersed PtNPs measuring 2–5nm were detected by high-resolution transmission electron microscopy, whereas palladium and platinum nanoparticles measuring 10–25 nm were found. [35]. Aucore Agshell nanoparticles derived from D. bulbifera reduced the biofilm of A. baumannii by 83.68 0.09%. The biofilms of P. aeruginosa, E. coli, and S. aureus were suppressed by 18.93 1.94%, 22.33 0.56%, and 30.70 1.33%, respectively. Uncontrolled cellular outflow leading to cell death was confirmed by SEM and AFM. [36] The study reported in this article showed that, in comparison to a reference drug, an extract of D. bulbifera cultured in methanol had strong antiproliferative efficacy. The leaves of this species may function as natural antioxidants, as evidenced by the significant antioxidant qualities of the plant's methanol, ethyl acetate, and hexane extracts when compared to ascorbic acid. Thus, leaf extracts' antiproliferative qualities validate the herb's historic uses to treat a range of illnesses, including breast cancer. [37]. Chloroform and methanol extracts from the vegetative organ of D. bulbifera kill T47D breast cancer cells. With an IC50 of 115.63 g/mL, leaf chloroform extract exhibits the strongest cytotoxic effect. The greatest cytotoxic activity against breast cancer (T47D) is achieved when F5 and F6 are mixed with ethyl acetate: methanol eluent. The IC50 for both fractions was 14.55 g/mL. T47D cells are cytotoxically affected by potential fractions, however SI > 10 Vero cells are unaffected. The potential fraction contained terpenoids and alkaloids.(38).

Effects on Thyroid Glands

Subacute thyroiditis had been successfully treated with D. bulbifera. [39]. In another study, Sprague-Dawley (SD) rats treated with sodium levothyroxine (160 lg/kg, 5 days) and extract of D. bulbifera (0.75 or 1.5 g/kg) showed a decrease in thyroxine (T4) concentration and triiodothyronine (T3)-uptake level. The findings indicated that D. bulbifera reduced excess thyroid hormone and increased metabolism, which improved the hyperthyroid state. [40].

Phytochemical Analysis

The findings of a preliminary phytochemical screening of the ethanolic, methanolic, and aqueous extracts of D. bulbifera tuber are shown. Alkaloids, carbohydrates, flavonoids, glycosides, phenols, steroids, tannins, saponins, and other substances were examined in the extracts. Methanolic, ethanolic, and aqueous extracts have the highest concentrations of bioactive chemicals. Certain phytochemicals found in organic solvents, such as terpenoids, steroids, and coumarin, were entirely absent from the aqueous extract. In addition, none of the extracts included any proteins.

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