CHAPTER ONE

1.0 INTRODUCTION

Ginger (zingiber officinale), Roscoe belonging to the Family Zingiberaceae, is a perennial herb with thick tuberous rhizomes. The erect leafy aerial stem grows up to approximately 1 meter in height and has purple flowers (fig.1). Its roots are used as spice in cooking throughout the world. The ginger plant has a long history

of cultivation known to originate in China and then spread to India, South East Asia, West Africa and the Caribbean (Weiss, 1997; McGee, 2004). Ginger contains up to 3% of an essential oil that causes the fragrance of the spice (O’Hara et al, 1998).

The main constituents are sesquiterpenoids with (-)-zingiberene as the main component. Other components include β-sesquiphell and renebisabolene and farnesene which are also sesquiterpenoids,( β-sesquiphellandrene, cineol and citra)( Opdyke,1974 ;O’Hara et al,1998).

The pungent taste of ginger is due to nonvolatile phenylpropanoid – derived compounds, gingerols and shogaols. The shogaols are formed from gingerols when ginger is dried or cooked. Zinger is also produced from gingerols during this process, and it is less pungent and has a sweet aroma (O’Harold,2004). Ginger is a minor chemical irritant, and has asialagogue action, stimulating the production of saliva(O’Hara et al, 1998). Mature ginger roots are fibrous and nearly dry. They can be cooked as an ingredient in man is often added as a sweetener; sliced orange or lemon fruit may also be added. The juice of ginger roots is extremely potent and is often used as spice to flavour dishes such as seafood, mutton, snacks or stew. Powdered dry ginger roots(ginger powder) are typically used to add spiciness to ginger bread and other recipes. Ginger is also made into candy and used as flavoring for cookies, crackers and cakes as well as flavour in ginger ale-a sweet, carbonated, non-alcoholic beverage. Ginger bread, ginger snaps, ginger cake and ginger biscuits(McGee,2004).

Ginger has been used by traditional Chinese and Indian medicine for over 25 centuries. Ginger was brought to Mexico by the Spaniards and later introduced to Jamaica, the latter currently being one of the world’s foremost producers of this species. Ginger is used in Mexican traditional medicine, mainly for gastrointestinal complaints.

In recent times, ginger has been introduced into various tropical countries where diverse chemo types have been developed . Ginger is primarily used to treat nausea, but it is also used as an anti-inflammatory, a pain remedy, a warming remedy and a cholesterol-lowering herb. Randomized controlled trials support its use in preventing nausea.

Case studies suggest usefulness in treating migraines and inflammatory arthritis, but no randomized trials have been reported. Animal studies suggest thermogenic effects, but this has not been evaluated in humans. Data are insufficient to recommend ginger as a cholesterol-lowering supplement. Given its long history of use as a food, ginger is presumed safe for supplemental use. Because of its effects on platelet aggregation and thromboxane synthesis in vitro, some herbalists suggest caution for patients taking anticoagulants or those scheduled for surgery; on the other hand, no clinically significant anticoagulant effects have been documented. It is on the Generally Recognized as Safe (GRAS) list, but no studies have specifically evaluated ginger’s safety during pregnancy, lactation or during childhood. A related species has uterotonic effects in animals, which has led some herbalists and the German Commission E to recommend that ginger be avoided during pregnancy.

Medically ginger is used as a stimulant and carminative, and is used frequently for dry pepsia and colic (O’Hara et al, 1998). It has a sialaggogue action, stimulating the production of saliva. It is also used to disguise the taste of medicines. Ginger promotes the release of bile from the gall bladder (Opdyke, 1974; Katoet al, 1993; O’Hara et al, 1998). Ginger may also decrease joint pain from arthritis, may have blood thinning and cholesterol lowering properties and may be useful for the treatment of heart diseases and lungs diseases (Opdyke, 1974; Kato et al, 1993; O’Hara et al,1998; Kuschener and Stark, 2003). The characteristic dour and flavour of ginger root is caused by a mixture of ginger, shoagoles and gingerols, volatile oils that make up about 1-3% of the weight fresh ginger.

The gingerols increase the motility of the gastrointestinal tract and have analgesic, sedative and antibacterial properties (O’Hara et al, 1998). Ginger has been found effective by multiple studies for treating nausea caused by seasickness, morning sickness and chemotherapy (Ernst and Phittler, 2000). Ginger has been reported to be effective for the treatment of inflammation, rheumatism, cold, heat cramps, and diabetes (Al-Amin, 2006; Afshari, 2007).

Allergic reactions to ginger include heartburn, bloating, gas, belching and nausea (particularly if taken in powdered form). Unchewed fresh ginger may result in intestinal blockage, and individuals who have hadulcers, inflammatory bowel diseases or blocked intestines may react badly to large quantities of fresh ginger (Opdyke, 1974; O’Hara et al, 1998). Ginger can also adversely affect individuals with gallstones, and may affect blood pressure, clotting, and heart rhythms(O’Hara et al, 1998).

The aim and objective of the present study was to investigate the antibacterial activity and bacterial growth inhibition of ginger extracts.

The soxhletethanolic extracts was obtained by soxhlet extraction of 20g of ginger powder in 100ml of 95% ethanol at 78^oC using soxhlet apparatus. The extract was then concentrated to 20ml on a water bath and dried at room temperature.

The n-hexane extract was obtained by dissolving 20g of the powdered ginger in 100ml of  hexane in a conical flask. The mixture was stirred, covered, and allowed to stand for 24hrs, and filtered using sterile Whitman No.1 filter paper. The filtrate was concentrated to 20ml on a water bath and evaporated to dryness at room temperature.

The ethyl acetate and water extracts were obtained by repeating the above procedure for hexane. The various extracts were used for the analysis of antibacterial activities and bacterial inhibition assay.