Effect of aqueous extract of psidium guajava (guava) leaves on some haematological parameters

Introduction

Plants play an essential role in the health care needs for the treatment of diseases and to improve the immunological response against much pathology. Plants extracts contains potentially curative substances. Some of these extracts can boost the humoral and cell medicated immunity against virus, bacteria, fungi, protozoa and cancer (Brochers et al., 2000).

Guava (Psidium guajava) belonging to the family Myrtaceae is originated in the tropical south America and grows widely in Bangladesh, India, Thailand, Brazil, Florida, west indies, California and also in several African countries (Pathak and Ojha, 1993).

The main constituents of guava are vitamin, tannins, phenolic compounds, flavonoids, essential oils, sesquiterpene, alcohol and Triterpenoic acids. These and other compounds are related to many health effects of guava. Some authors have found high concentration of carotenoids (beta-carotene,lycopene and beta-cryptocanthin), vitamin c

and polyphenols in guava pulp (Oliveria, Lobato, Ribero, Santana and Chaves, 2010; Ramirez and Delagaye, 2011). Lycopene has been correlated with the prevention of cardiovascular damage because of its positive effect on dyslipidemia. It is generally known that  the consumption of a variety of local herbs and vegetables by man contributes significantly to the improvement of human health, in terms prevention and cure of diseases because plants has long serve as a useful  and natural source of therapeutic agent (Chevellier, 1996).

Moreover, traditional medicine is greatly relied upon especially by rural dwellers, for the treatment of various ailment; traditional doctors or healers are dispensers of such concoctions. Guava (Psidium guajava linn.) is a common shade tree or shrub in the door yard gardens in the tropics. The tree is easily identified by its distinctive thin, smooth, copper-coloured bark that flakes off, showing a greenish layer beneath. It has been reported that the phytochemical analysis of more than 20 isolated compounds including alkaloids, carotenoids, essential oil, fatty acids, lectins, phenols, saponins, tannins, etc. of guava leaf products are revealed. (Begum et al., 2002).

The main active constituent in the plant is quercetin. Spasmolytic and antidiarrheal effects are associated with its quercetin-derived, flavonoid glycosides, which supports the use of this ancient leaf remedy in treating gastrointestinal disorders (Lozoya et al., 2002). The decoctions made from the leaves and/or bark of Psidium guajava have been reported to be used by many tribes for diarrheal, dysentery, sore throat, vomiting, stomach upsets, vertigo and to regulate menstrual periods, throughout the tropical Amazon and India. Moreover, tender leaves are chewed for bleeding gums and bad breath, and it is said to prevent hangovers (if chewed before drinking). According to the report Indians throughout the Amazon gargle a leaf decoction for mouth sore, bleeding gums, or use it as douche for vaginal discharge and to tighten and tone vaginal walls after a child birth (Nwogu et al., 2007).

Conceptual framework

Psidium guajava is a fruit-bearing tree commonly known as guava, which belong to the family Myrtaceae. The French call it goyave or goyavier; the Dutch, guyaba, goeajaeba; the Surinamese, guave and the Portuguese, goiaba or goaibeira. It is generally known as guava which grows up to 35 feet tall. It is widely grown for its fruit in the tropics, with about 133 genera and more than 3,800 species. The leaves and bark of Psidium guajava tree have a long history of medicinal uses that are still employed today (Nwinyi et al., 2008). Guava contains broad spectrum of phytochemicals including polysaccharides, vitamins, essential oils, minerals, enzymes, proteins, alkaloids, glycosides, steroids, flavonoids, tannins, saponins (Begum et al., 2002).

Guava grows nearly throughout India up to 1500m in height and is cultivated commercially in almost all states, the total estimated area being 50,000 hectares. Guava trees have spread widely throughout the tropics because they thrive in a variety of soils, propagate easily and bear fruits quickly. The fruits are enjoyed by birds and monkeys, which disperse guava seeds and cause spontaneous dumps of guava sapling to grow throughout the rainforest (Begum et al., 2002).

Origin of psidium guajava

The apple guava or common guava (Psidium guajava) is a large tropical evergreen shrub or small shade tree. It is a native to and widely distributed in Mexico and central America. However, the plant is cultivated today from the west coast of Africa to the pacific region, including India and China with varieties. Originally introduced over the past 300 years from the United States. The guava berry is an important tropical fruit that is mostly consumed fresh. The fruit contains several small seeds and consist of a fleshy pericarp and seed cavity with palp (Lozoya, 2002). The tree is easily identified by its distinctive thin, smooth, copper layer beneath. It is the hardest tropical fruit trees and excels most of the other fruit crops in productivity and adaptability. Various cultivars have white, pink, or red flesh and a few also feature red (instead of green) skin. Highly acceptable, guavas can be easily grown as container plants in temperate regions throughout their ability to bloom ad  set fruits in somewhat less predictable. In some tropical locales, guava can become invasive. It has become a major problem in the Galapagos Islands. The plant is used in many different shampoo products for its scent. It is also becoming a popular bonsai species and it is currently quite popular in India and eastern Asia (D’Cruz and Mark, 2011).

Scientific classification of guava: (D’Cruz and Mark, 2011).

Phytochemistry

Guava is rich in tannin, phenols, triterpenes, flavonoids, essential oil, saponins, carotenoids, lectins, vitamins, fibre and fatty acids. Guava fruit is higher in vitamin C than citrus fruits (80 mg of vitamin in 100g of fruit) and contains appreciable amount of vitamin A as well. Guava fruits are also a good source of pectin (Sunttornusk, 2002).

The leaves of guava are rich in flavonoids, particularly quercetin. It has demonstrated antibacterial and anti-diarrhoeal effects and is able to relax the intestinal smooth muscle and inhibit bowel contractions. Guava has antioxidant properties attributed to polyphenols found in its leaves. The bark of guava tree contains considerable amount of tannins (11-27%), and hence is used for tannin and dyeing purposes. Leucocyanidin, Leuctic acid, ellagic acid and amritoside have been isolated from the stem bark. Five constituents, including one new pentacyclic triterpenoid: guajanoic acid and four known compounds: beta-sitosterol, uvaol, oleanolic acid and ursolic acid, have been recently isolated from the leaves of P. guajava (Begum et al., 2004).

Nutritional value

Guavas are rich in dietary fibre and vitamin C, with moderate levels of folic acid. Having generally broad, low-calorie profile of essential nutrients, a single common guava (P. guajava) fruit contains about four times the amount of vitamin C as an orange (Hassimotto and Genovese, 2005). The food value and content of guava fruit is listed in table 1 below. However, nutrient content varies across guava cultivars. Although the strawberry guava (P. litorale var. cattleianum), notably containing 90mg of vitamin C per serving. Guavas contain both carotenoids and polyphenols the major classes of antioxidant pigments, giving them relatively high potential antioxidant value among plant foods (Linda et al., 2004).

Table 1: Food value of Guava fruit (Kamanth et al., 2008)

Chemical composition of the various parts of guava (Psidium guajava Linn.)

According to Paniandy, Chane-ming and Peribattesh, (2008), these are some of the chemical composition of the various parts of guava such as the fruits, leaves, bark, root and seed.

Fruit constituents

Vitamin C, Vitamin A, iron, calcium, manganese, phosphoric, oxalic and malic acids, saponisn combined with oleanolic acid. Morin-3-O-α-L-lyxopyranoside, morin-3-O-α-L-arabopyranoside, flavonoids, guailavarin and quercetin. Essential oil contains hexanal, -2-hexenal, 3-hexenyl acetate and phenol, while β-caryophyllene, nerolidol, 3-phenylpropyl acetate, 3-penten-2-ol and 2-butenyl acetate.

Leaves constituents

α-pinene, β-pinene, llimonene, menthol, terpenyl acetate, isopropyl alcohol, longicyclene, caryophyllene, β-bisabolene, caryophyllene oxide, β-copanene, farnesene, humulene, selinene, cardinene, and curcumene, malic acids, nerolidiol, β-sitosterol, ursolic, crategolic and guayavolic acids, cineol, quercetin, 3-L-4-pyranoside (essential oil), resin, tannin, eugenol, caryophyllene (1a α-, 4a α-, 7 α-, 7a β-, 7b α-) triterpene oleanolic acid, triterpenoids, flavinone-2-2-ene, prenol, dihydrobenzophenanthridine and cryptonine.

Bark constituents

Polyphenols, resin and crystals of calcium oxalate.

Root constituents

Tannin, leukocyanidins, sterols, gallic acid, carbohydrates, salts, tannic acid.

Seed constituents

Proteins, starch, oils, phenolic, flavonoid compounds, flavonol glycoside,quercetin-3-O-β-D-(-2-O-galloyglucoside)-4-O-vinylpropionate.

Potential medical uses

Since the 1950s, guavas particularly the leaves have been a subject for diverse research on their constituents, pharmacological properties and history in folk medicine. Most research, however, has been conducted on apple guava (Psidium guajava Linn.) with other species remaining undefined. From preliminary medical research in laboratory models extract from apple guava leaves or bark are implicated in therapeutic mechanisms against cancer, bacterial infections, inflammation and pain. Essential oils from guava leaves display anti-cancer activity in vitro.

Guava leaves are used in folk medicine as a remedy for diarrheal, and as well as the bark, for their supposed antimicrobial properties and as an astringent. Guava leaves or bark are used in traditional treatments against diabetes (Mukhtar et al., 2006). In Trinidad, a tea made from young leaves is used for diarrhea, dysentery and fever (Manosroi, Dhumtanom and Manosroi, 2006).

Types of guavas

According to Charles (2014) there are three types of guavas, namely:

Tropical guavas

These are known scientifically as the apple guava (Psidium guajava) they are the best tasting with the largest fruit with the most juice. These are the most frost tender Guavas. Tropical Guavas grow up to 10 to 15 feet high and wide.

Strawberry guavas

Psidium lucidium are shrubby trees with tart but very flavourful fruit that is small than a tropical guava. Strawberry guavas are very productive and grown 12 feet high and wide.

Pineapple Guavas

Feijoa sellowiana is a South African plant are related to other guavas. Their fruit is tangy with a citrus flavour. This is the most frost tolerant variety. Pineapple guavas grow to 15 feet high and wide and have a wonderful gnarled trunk and make good substitute for olive trees

Varieties of guava

He further illustrated the different varieties of guavas such as;

Strawberry guava (Psidium lucidium): These guavas are hardy and adaptable evergreen shrubs or small trees. Small fruit fruits are very juicy and flavourful. The fruit are produced over a long season August through December.

Pineapple guava (Feijoa sellowiana): The most cold hardy guava. Pineapple guavas make excellent large shrubs or small trees with attractive flowers, foliage and bark. The fruit is plentiful and tangy making excellent jellies, the flowers are also edible.

Beamonth: Developed on Oahu, Hawaii, this guava produces fruit perfect for juicing. Beamonth is a vigorous plant, producing medium sized fruit with pink sweet juicy flesh. The trees are productive bearing fruit fall through winter.

China white: producing large (up to a pound) white fleshed and green skinned fruit are very sweet and choice. The fruit can be eaten unripe and has very aromatic flesh. These guavas are tough and vigorous producing fruits September through December.

Medicinal and pharmacological properties of psidium guajava

Its traditional use against diarrhoea, gastroenteritis and other digestive complaints has been validated in numerous clinical studies. In a study including 17 Thai medicinal plants on anti-proliferative effects on humans mouth epidermal carcinoma and murine. Leukaemia cells using MIT assay, guava leaf showed anti-proliferative activity, which was 4.37 times more than vincristine (Manosroi et al., 2006). The antimicrobial activities of Psidium guajava and leaf extracts, determined by disk diffusion method (zone of inhibition), were compared to tea tree olive (TTO), doxycycline and clindamycin antibodies. It was shown that Psidium guajava leaf extract might be beneficial in treating acne especially those that have anti-inflammatory activities (Qadan et al., 2005). Guava leaf extract has also shown to have tranquilizing effect on intestinal smooth muscles, inhibit chemical processes found in diarrhoea and aid in the re-absorption of water in intestines. The effective use of guava in diarrhoea, dysentery and gastroenteritis can also be related to guava’s documented antibacterial properties (Tona et al., 2000).

Health benefits of guava leaves

According to the ‘Journal of Smooth Muscles Research” published in 2008, Guava plant leaves are known as a natural pain reliever. They contain polyphenols, flavonoids, and carotenoids which make them useful in treating numerous disease and conditions such as;

Helps weight loss

Guava leaf extracts helps with weight loss by preventing complex starches that are consumed in your diet from being able to convert into sugars. The guava leaves prevent the transition of carbohydrate to usable compounds when being broken down in the liver.

Balance blood sugar levels

Guava leaves provides individuals with diabetes the benefit of slowing down the sugar absorption into the blood by offering the body high levels of fibre. The taking of guava leaf extracts subdues high blood sugar levels and can prevent the start of type 2 diabetes (Mukhtar et al., 2006).

Aid with gastric cancer

According to a researcher that was published in 2011 in “food chemistry”, there is evidence that guava leaf extract has the potential to treat individuals with gastric cancer. Researchers found that when the extract of the plant is consumed it results in apoptosis (which means that gastric cancer cells kill themselves).

Treats diarrhoea

According to the “Journal of Smooth Muscle Research” in 2008 guava leaves extract can treat diarrhoea. It can be taken as tea, capsule, or by adding a few drops of essential oil form into a cup of warm water then drinking it. When the extract is taken as essential oil it provides astringent that binds up loosed bowels to treat diarrhoea. This astringent provides antibacterial and disinfectant properties which aid in removing extra mucus from the intestines.

Side effects of guava

Guava has recently demonstrated cardiac depressant activity and should be used with caution by those on heart medication. Most guava fruits have shown to lower blood sugar levels and should be avoided by people with hypoglycemia. Pregnant women and breast feeding mothers in particular must avoid overuse of guava through various herbal and alternative medications. Eating of too much guava may cause tooth decay, nail and hair thinning, weakness, skin problem due to high fructose availability (Lozaya et al., 2002).

Haematological parameters

Haematological parameters are those parameters that are related to blood forming organ (Bamishaye and Mohammed, 2010). They include packed cell volume (PCV), which is the volume of percentage of red cell in whole blood, differential white cell count, which is the determination of the different white cell in a patient blood and total white blood cell count (WBC) which is the number of white cells in one cubic millimeter of blood (Abayomi, 2007).

Packed Cell Volume (PCV) or Hematocrit (HCT)

Hematocrit (Ht or HCT, British English spelling hematocrit), also known as packed cell volume (PCV) or erythrocyte volume fraction (EVF) is the volume percentage (%) of red blood cells in blood. It is normally 45% for men and 40% for women. The packed cell volume (PCV) can be determined by centrifuging heparinized blood in a capillary tube (also known as a microhematocrit tube) at 10,000 RPM for five minutes. This separates the blood into layers. The volume of packed red blood cells divided by the total volume of the blood sample gives the PCV (Jelkmenn, 2004).

White blood cells and differential count

White blood cells (WBC) are heterogeneous group of nucleated cells that can be found in circulation for at least a period of their life. Their normal concentration in blood varies between 4000 and 10,000 per microliter. They play a most important role in phagocytosis and immunity and therefore in defense against infection. WBC are classified into granulocytes, lymphocytes and monocytes. Granulocytes owe their name to the presence of distinct cytoplasmic granulation. Three varieties are recognized: neutrophils (or polymorphonuclear granulocytes), eosinophils and basophils (Cline and Huttle, 1984).

Normal Values of Some Haematological Parameters in Rats (FL-Hazim, 2001).

Haematological Parameters                     Normal values

1. Packed cell volume                              36 – 54 (%)
2. Total white cell count 6 -18×10⁹ cells per litre
3. Differential white cell count

Normal values

Neutrophil                                                  10-30%

Lymphocyte                                              69-86%

Monocyte                                                  0-5%

Eosinophil                                                 0-6%

Basophil                                                    0-1%

Effects of aqueous extract of psidium guajava leaves on some haematological parameters

The oral administration of the Psidium guajava has effect on some of the haematological parameters of wistar albino rats, in a research conducted Aruna, Wazida and Sinha (2013) it was discovered that the oral administration of aqueous extract of Psidium guajava had significant effect on Red Blood Cell (RBC), Haemoglobin (Hb), Mean Cell haemoglobin concentration (MCHC), Packed Cell Volume (PCV), Mean Cell Volume (MCV), Neutrophils, Basophils, Monocytes, Lymphocytes, and Eosinophils. The white blood cell (WBC) was significantly elevated (P<0.05) in the group treated with 250 mg/kg body weight, where as the

count significantly decreased (P<0.05) in 500 mg/kg body weight. The platelet also significantly increased (P<0.05) in the rats treated with both the doses, and they should be used and recommended for the management of anaemia and immunity dependent diseases.

Moreover, in a research conducted by Friday, Iniobong and Moses (2010), the oral administration of aqueous extract of Psidium guajava leaves on some haematological indices in male and female rats showed that the Red Blood Cell Counts, Haematocrit (PCV) and Haemoglobin Concentration increased significantly (P<0.05). And also no significant effect (P>0.05) on the white blood cell count was observed to be associated with treatment of both male and female rats with the extracts.

The oral administration of P. guajava shows antioxidant activity and thus in a hypertensive rats, a guava leaf aqueous extract produces a dose-dependent reduction in systemic arterial blood pressure and heart rate. It revealed significant (P<0.05)reduction in the value of PCV, Hb, RBC, WBC, neutrophil, lymphocytes, monocytes and which indicate a reduction of red blood cell production that causes anaemia in rats fed with P. guajava extracts (Okonkwo, Lyadi and Effiong, 2004).

Component of psidium guajava responsible for changes in haematological parameters

Friday et al., (2010), the main active constituent in aqueous extract of Psidium guajava is quercetin which is a flavonoid compound (quercetin-3-o-α-1-arabinopyranoside). Therefore the high dose (500 mg/kg body weight) of P.guajava extracts is useful in reducing the cardiovascular disease as some studies suggested, various mechanism by which flavonoid exert it antiplatelet property by lowering intercellular Ca²⁺ levels; alteration in the metabolism of CAMP and thromboxane A₂ (Kang et al., 2001). The haemoglobin content, RBC and PCV are also significantly increased which stimulate erythropoietin release in the kidney which is the humoral regulator of RBC production (Degruchy, 2006).

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