Psidium guajava L, belonging to the Myrtacea family, has been reported to have anti-diarrheal, hepatoprotective, hypoglycemic, lipid lowering, antibacterial and antioxidant activities. It contains important phytoconstituents such as tannins, triterpenes, flavonoid:quercetin, pentacyclic triterpenoid:guajanoic acid, saponins, carotenoids, lectins, leucocyanidin, ellagic acid, amritoside, beta-sitosterol, uvaol, oleanolic acid and ursolic acid. In view of the immense medicinal importance of the plant, this review is an effort to compile all the information reported on its phytochemical and pharmacological activities. The present review is an attempt to generate interest among the masses regarding its immense potential in preventing and treating several common diseases. Psidium guajava L is a fruit-bearing tree commonly known as guava, which belongs to the family Myrtaceae. The French call it goyave orgoyavier ; the Dutch, guyaba , goeajaaba ; the Surinamese, guave or goejaba ; and the Portuguese, goiaba or goaibeira. Hawaiians call it guava or kuawa . In Guam, it is abas . In Malaya, it is generally known either as guava or jambu batu (Morton, 1987). . Guava grows nearly throughout India up to 1500 m in height and is cultivated commercially in almost all states, the total estimated area being 50,000 hectares. The important guava-growing states in India are Uttar Pradesh, Bihar, Maharashtra, Assam, West Bengal and Andhra Pradesh. Cultivated varieties grow about 10 m in height and produce fruits within 4 years. Wild trees grow up to 20 m high and are well branched. The tree can be easily identified by its distinctive thin, smooth, copper-colored bark that flakes off, showing a greenish layer beneath. 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 saplings to grow throughout the rainforest (Wealth of India, 2003).
The leaves and bark of guava tree have a long history of medicinal uses. In India, decoction of the leaves and bark of guava is used to cure diarrhea, dysentery, vomiting and sore throats, and to regulate menstrual cycles. The tribes of the Amazon use leaf decoction for mouth sores, bleeding gums, as douche for vaginal discharge and to tighten and tone up vaginal walls after labor. Guava is cultivated throughout the tropics. Commercially, the fruit is consumed raw or used in making jams, jellies, pastes and juice. Guava leaves are official in Dutch Pharmacopoeia. Guavas are free from fat and cholesterol. They are also an excellent source of fiber, potassium and vitamin A.
Guava is rich in tannins, phenols, triterpenes, flavonoids, essential oils, saponins, carotenoids, lectins, vitamins, fibre and fatty acids. Guava fruit is higher in vitamin C than citrus fruits (80 mg of vitamin C in 100g of fruit) and contains appreciable amounts of Vitamin A as well Guava fruits are also a good source of pectin (Sunttornusk L, 2005).
The leaves of guava are rich in flavonoids, particularly quercetin. It has demonstrated antibacterial and anti-diarrheal 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 amounts of tannins (11-27%), and hence is used for tanning and dyeing purposes. Leucocyanidin, luectic 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).
Biological Activity and Clinical Research
The long history of guava use has led modern-day researchers to study guava...