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FLAVONOID

 

 

Flavonoid merujuk kepada tumbuhan metabolit sekunder. Mengikut penamaan IUPAC, flavonoid boleh diklasifikasikan kepada 3 iaitu :

1)     flavonoids, didapati daripada struktur 2-phenylchromen-4-one (2-phenyl-1,4-benzopyrone)

2)     isoflavonoids, didapati daripada struktur 3-phenylchromen-4-one (3-phenyl-1,4-benzopyrone)

3)     neoflavonoids, didapati daripada struktur 4-phenylcoumarine (4-phenyl-1,2-benzopyrone)

   
 

Karya Dr. Joseph Mercola dan Racheal Droege yang bertajuk Want to live longer? Eat more Flavonoids, menyatakan bahawa flavonoids diperlukan oleh sistem  badan kita sebagai:

         Membantu minda dalam mengingat dan menumpukan perhatian serta digunakan bagi merawat masalah kurang daya tumpuan.

         Melancarkan keberkesanan Vitamin C di dalam rangkaian anti-oksida.

         Mengawal nitrit oksida yang mana, dapat mengawal peredaran darah.

         Menjaga kesihatan jantung dalam tiga cara iaitu mengelakkan pembekuan darah, mengawal pengoksidaan LDL (kolestrol tidak baik) dan mengurangkan tekanan darah tinggi.

         Meningkatkan fungsi seksual bagi kaum lelaki

         Mengurangkan bengkak dan menambah fungsi imunisasi.

   

Secara asas, flavonoids membantu tubuh di dalam perkara-perkara berikut:

         Mengurangkan risiko menghidapi barah.

       Pengambilan flavonoids membantu merendahkan risiko barah pankreas, barah paru-paru, barah prostat.

         Mengurangkan risiko angin ahmar dan penyakit jantung.

       Flavonoids membantu mengelakkan pembekuan darah dan arteri yang tersumbat. Ia juga mampu mengurangkan risiko kematian akibat serangan angin akhmar dan penyakit jantung.

         Melindungi diri daripada kesan-kesan penuaan.

       Penuaan berlaku apabila peningkatan usia, di mana berlaku penurunan tahap keaktifan tubuh. Selain daripada itu, penuaan berlaku disebabkan oleh pengumpulan gula di dalam kanta mata. Pengambilan flavonoids dengan secukupnya dapat mengatasi masalah penuaan kerana ia mampu memperbaiki perjalanan serta peredaran darah pada otot mata.    

         Mengurangkan radang pada sendi dan otot.

       Kandungan flavonoids yang cukup pada badan juga dapat mengurangkan radang pada sendi dan otot yang mana, boleh menyebabkan masalah gaut, fibronyalgia dan rhuematoid arthritis.

         Mengatasi masalah kepanasan suhu tubuh akibat menopouse.

       Flavonoids juga mampu memulihkan semula  kekeringan akibat menopouse terutamanya, bagi  wanita yang sudah berumur.

         Melengahkan masalah gejala asma dan selsema.

       Flavonoids membantu menguatkan tubuh daripada alahan terhadap debu dan habuk. Flavonoids juga mengurangkan masalah radang peparu serta melancarkan sistem pernafasan.

         Meringankan masalah radang kulit dan gigitan serangga.

       Flavonoids adalah bahan paling bagus untuk melindungi kulit daripada masalah radang kulit dan gigitan serangga.

 

  KENYATAAN:

Artikel di bawah ini merupakan perbandingan kandungan flavonoids dalam mas cotek berbanding herba terpilih lain.

Petikan yang kami paparkan adalah dari penulisan atau kajian asal tanpa diubahsuai - Harap maklum.

 

 

  Flavonoids
 

Dr. Donald R. Buhler

Antioxidant Activities of Flavonoids

Department of Environmental and Molecular Toxicology
Oregon State University


Dr. Cristobal Miranda


Summary: Flavonoids are compounds found in fruits, vegetables, and certain beverages that have diverse beneficial biochemical and antioxidant effects. Their dietary intake is quite high compared to other dietary antioxidants like vitamins C and E. The antioxidant activity of flavonoids depends on their molecular structure, and structural characteristics of certain flavonoids found in hops and beer confer surprisingly potent antioxidant activity exceeding that of red wine, tea, or soy.

Flavonoids are polyphenolic compounds that are ubiquitous in nature and are categorized, according to chemical structure, into flavonols, flavones, flavanones, isoflavones, catechins, anthocyanidins and chalcones. Over 4,000 flavonoids have been identified, many of which occur in fruits, vegetables and beverages (tea, coffee, beer, wine and fruit drinks). The flavonoids have aroused considerable interest recently because of their potential beneficial effects on human health-they have been reported to have antiviral, anti-allergic, antiplatelet, anti-inflammatory, antitumor and antioxidant activities. 

Antioxidants are compounds that protect cells against the damaging effects of reactive oxygen species, such as singlet oxygen, superoxide, peroxyl radicals, hydroxyl radicals and peroxynitrite. An imbalance between antioxidants and reactive oxygen species results in oxidative stress, leading to cellular damage. Oxidative stress has been linked to cancer, aging, atherosclerosis, ischemic injury, inflammation and neurodegenerative diseases (Parkinson's and Alzheimer's). Flavonoids may help provide protection against these diseases by contributing, along with antioxidant vitamins and enzymes, to the total antioxidant defense system of the human body. Epidemiological studies have shown that flavonoid intake is inversely related to mortality from coronary heart disease and to the incidence of heart attacks. 

The recognized dietary antioxidants are vitamin C, vitamin E, selenium, and carotenoids. However, recent studies have demonstrated that flavonoids found in fruits and vegetables may also act as antioxidants. Like alpha-tocopherol (vitamin E), flavonoids contain chemical structural elements that may be responsible for their antioxidant activities. A recent study by Dr. van Acker and his colleagues in the Netherlands suggests that flavonoids can replace vitamin E as chain-breaking anti- oxidants in liver microsomal membranes. The contribution of flavonoids to the antioxidant defense system may be substantial considering that the total daily intake of flavonoids can range from 50 to 800 mg. This intake is high compared to the average daily intake of other dietary antioxidants like vitamin C (70 mg), vitamin E (7-10 mg) or carotenoids (2-3 mg). Flavonoid intake depends upon the consumption of fruits, vegetables, and certain beverages, such as red wine, tea, and beer. The high consumption of tea and wine may be most influential on total flavonoid intake in certain groups of people. 

The oxidation of low-density lipoprotein (LDL) has been recognized to play an important role in atherosclerosis. Immune system cells called macrophages recognize and engulf oxidized LDL, a process that leads to the formation of atherosclerotic plaques in the arterial wall. LDL oxidation can be induced by macrophages and can also be catalyzed by metal ions like copper. Several studies have shown that certain flavonoids can protect LDL from being oxidized by these two mechanisms. 

Antioxidant flavonoids
(listed in order of decreasing potency)

  • Quercetin (a flavonol in vegetables, fruit skins, onions) 
  • Xanthohumol (a prenylated chalcone in hops and beer)
  • Isoxanthohumol (a prenylated flavanone in hops and beer) 
  • Genistein (an isoflavone in soy)

Pro-oxidant flavonoids

  • Chalconaringenin (a non-prenylated chalcone in citrus fruits) 
  • Naringenin (a non-prenylated flavanone in citrus fruits)

The capacity of flavonoids to act as antioxidants depends upon their molecular structure. The position of hydroxyl groups and other features in the chemical structure of flavonoids are important for their antioxidant and free radical scavenging activities. Quercetin, the most abundant dietary flavonol, is a potent antioxidant because it has all the right structural features for free radical scavenging activity. 

Recently, chalcone and flavanone flavonoids with prenyl or geranyl side chains have been identified in hops and beer by Dr. Fred Stevens and Dr. Max Deinzer at Oregon State University. Hops are used in beer for flavor. Xanthohumol (a chalcone) and isoxanthohumol and 6-prenylnaringenin (flavanones) are the major prenyl-flavonoids found in beer. Although the antioxidant activities of these compounds have not been studied, these flavonoids may be responsible for the antioxidant activity of lager beer, which is higher than that of green tea, red wine, or grape juice as reported earlier by Dr. Joe A. Vinson from the University of Scranton in Pennsylvania. Xanthohumol is found only in beer but in small concentrations. 

To assess the antioxidant activity of the prenylated flavonoids, we-in collaboration with LPI researchers-evaluated the capacity of these flavonoids to inhibit the oxidation of LDL by copper. The antioxidant properties of the prenylflavonoids were compared to those of quercetin (a flavonol), genistein (the major isoflavone in soy), chalconaringenin (a non-prenylated chalcone), naringenin (a non-prenylated flavanone), and vitamin E. The possible interaction of xanthohumol, the major prenylchalcone in beer, with vitamin E to inhibit LDL oxidation induced by copper was also examined. 

Our results showed that the prenylchalcones and prenylflavones are effective in preventing LDL oxidation  initiated by copper and that the prenylchalcones generally have greater antioxidant activity than the prenylflavanones. Xanthohumol, the major prenylchalcone in hops and beer, is a more powerful antioxidant than vitamin E or genistein. However, xanthohumol was less potent than quercetin. The potency of xanthohumol as an antioxidant is markedly increased when combined with an equivalent amount of vitamin E. 

As reported in the Journal of Agricultural and Food Chemistry, we also found that the prenyl group plays an important role in the antioxidant activity of certain flavonoids. A flavonoid chalcone (chalconaringenin) and a flavanone (naringenin) with no prenyl groups act as pro-oxidants, i.e. they promote rather than limit the oxidation of LDL by copper. However, adding a prenyl group to these flavonoid molecules counteracted their pro-oxidant activities. 

Our work reveals that there are unique flavonoids in hops and beer that may be potentially useful in the preventionof human disease attributed to free radical damage. The observation that prenyl groups are important in conferring antioxidant activity to certain flavonoids may lead to the discovery or synthesis of novel prenylated flavonoids as preventive or therapeutic agents against human diseases associated with free radicals. Our encouraging results with xanthohumol suggest that this prenylchalcone should be further studied for its antioxidant action and protective effects against free radical damage in animals and humans. Preliminary studies have shown that xanthohumol is absorbed from the digestive tract in rats, and more studies are needed to evaluate the bioavailability of these interesting flavonoids in people. 

Further studies are also needed to establish the safety of xanthohumol or other flavonoids for use as dietary supplements since high doses of these compounds may produce adverse effects in humans, according to recent findings by Dr. Martyn Smith, professor of toxicology, University of California at Berkeley

  Flavonoids
 

Flavonoids


Phytochemical:

Flavonoids

 
Description:

Flavonoids are water soluble polyphenolic molecules containing 15 carbon atoms. Flavonoids belong to the polyphenol family. Flavanoids can be visualized as two benzene rings which are joined together with a short three carbon chain. One of the carbons of the short chain is always connected to a carbon of one of the benzene rings, either directly or through an oxygen bridge, thereby forming a third middle ring, which can be five or six-membered. The flavonoids consist of 6 major subgroups: chalcone, flavone, flavonol, flavanone, anthocyanins and isoflavonoids.
Together with carotenes, flavanoids are also responsible for the coloring of fruits, vegetables and herbs.

 

Distribution: Flavonoids are found in most plant material. The most important dietary sources are fruits, tea and soybean. Green and black tea contains about 25% percent flavonoids. Other important sources of flavonoids are apple (quercetin), citrus fruits (rutin and hesperidin),

 
Action of Flavonoids: Flavonoids have antioxidant activity. Flavonoids are becoming very popular because they have many health promoting effects. Some of the activities attributed to flavonoids include: anti-allergic, anti-cancer, antioxidant, anti-inflammatory and anti-viral. The flavonoids quercetin is known for its ability to relieve hay fever, eszema, sinusitis and asthma.
Epidemiological studies have illustrated that heart diseases are inversely related to flavonoid intake. Studies have shown that flavonoids prevent the oxidation of low-density lipoprotein thereby reducing the risk for the development of atherosclerosis.
The contribution of flavonoids to the total antioxidant activity of components in food can be very high because daily intake can vary between 50 to 500 mg.
Red wine contains high levels of flavonoids, mainly quercetin and rutin. The high intake of red wine (and flavonoids) by the French might explain why they suffer less from coronary heart disease then other Europeans, although their consumption of cholesterol rich foods is higher (French paradox). Many studies have confirmed that one or two glasses of red wine daily can protect against heart disease.
Tea flavonoids have many health benefits. Tea flavonoids reduce the oxidation of low-density lipoprotein, lowers the blood levels of cholesterol and triglycerides.
Soy flavonoids (isoflavones) can also reduce blood cholesterol and can help to prevent osteoporis. Soy flavonoids are also used to ease menopausal symptoms.

 
Research Reviews:
  • A flavonoid fraction from cranberry extract inhibits proliferation of human tumor cell lines
   

 

PERINGATAN:-

Adalah dengan ini dimaklumkan bahawa segala maklumat, keterangan dan testimoni yang dipaparkan tidak wajar dijadikan sebagai panduan mutlak (tanpa merujuk kepada ahli perubatan @ doktor) bagi tujuan untuk mengenal pasti atau mengubati sebarang jenis penyakit. Sila dapatkan khidmat nasihat dan diagnostik ahli perubatan @ doktor yang bertauliah untuk mengenal pasti penyakit dan rawatan. Manakala segala testimoni yang ada, merupakan pengalaman sebenar pengguna. Sebahagiannya sudah diuji secara klinikal, manakala sebahagian lainnya belum lagi diuji sedemikian.   

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