How plants' antioxidants slow prostate cancer, sight loss
More evidence is emerging why the same plant extract could be used to treat several diseases. CHUKWUMA MUANYA examines how antioxidants in plant extracts slow the progression of prostate cancer and sight loss, as well as boost endurance in athletes.
RESEARCHERS have shown in recent studies that men with prostate cancer who consumed the active compounds (antioxidants) in green tea demonstrated a significant reduction in serum markers predictive of prostate cancer progression.
Results of a recent year-long clinical trial conduced by researchers in Italy demonstrated that consumption of green tea polyphenols reduced the risk of developing prostate cancer in men with high-grade prostate intraepithelial neoplasia (HGPIN).
The results of the study was published in Cancer Prevention Research, a journal of the American Association for Cancer Research.
Green tea is the second most popular drink in the world, and some epidemiological studies have shown health benefits with green tea, including a reduced incidence of prostate cancer.
Before now, green tea has been linked to a positive effect on a wide range of conditions, including heart disease, cancer and Alzheimer's disease.
Also, Queen's University, Belfast academics, Ireland, have helped develop an antioxidant supplement, which may slow down sight loss in elderly people.
The supplement may help those affected by one of the leading cause of blindness in the world, a five-year research programme has found.
Prof. Usha Chakravarthy, from Queen's Centre of Vision and Vascular Science (CVVS), co-ordinated the study, which looked at nutritional supplements for patients with early age-related macular (AMD) degeneration and found that they helped sharpen vision.
Details of the findings were presented in Belfast recently by Chakravarthy and Dr. Stephen Beatty, head of Vision Research at the Waterford Institute of Technology.
They co-designed the study and the antioxidant supplement was developed with the advice of Prof. Ian Young from the School of Medicine, Dentistry and Biomedical Sciences at Queen's and scientists in eye care companies Dr. Mann Pharma and Bausch and Lomb.
AMD is an incurable eye disease, which causes blurring of central vision because of its effects on the macula, the central part of the retina.
Over 400 people across Ireland took part in clinical trials investigating whether carotenoids, rich antioxidants, which are found in fruit and vegetables, could prevent progression to the more serious late AMD.
When the eye disease progresses to late AMD, patients are unable to read, watch television or recognise people's faces as they only have peripheral vision, not central vision.
Meanwhile, United States researchers have demonstrated in a small study with healthy college students that eating a variety of fruits and vegetables rich in the antioxidant quercetin may boost endurance.
The 12 fit college students, who were not regular exercisers, were given quercetin supplements for seven days, which appeared to boost exercise endurance compared with a similar seven-day period without supplements, researchers report in the International Journal of Sports Nutrition and Exercise Metabolism.
Quercetin, a compound abundant in red apples, red onions, berries, cabbages and broccoli and green and black teas, is believed to have multiple antioxidant and anti-inflammatory and cell-energy activation properties that benefit health.
However, most previous research involved animals, report Dr. J. Mark Davis, at University of South Carolina in Columbia, United States and colleagues.
Until now, Nigerian studies and folklore have shown that plants could be used as a "cure all" (Gbogbonse in Yoruba and Ogwonnuoria in Igbo) because they are rich with antioxidants. They have been used in treating conditions such as headache, pain, diarrhoea, menstrual problems, venereal diseases, infertility, cancer among others.
Leading Nigerian researcher on antioxidant activity of Nigerian plants, Associate Professor Olukemi A. Odukoya, of the Department of Pharmacognosy, Faculty of Pharmacy College of Medicine University of Lagos (CMUL) told The Guardian that Nigerian plants were rich in antioxidants.
Odukoya have examined the antioxidant activity of Nigerian dietary spices and provided evidence to support the acclaimed role of plants as aphrodisiacs in traditional medicine. An aphrodisiac is a food, drink, drug, scent or device that can arouse or increase sexual desire or libido.
Indeed, plant foods, such as fruits, vegetables and whole grains contain many components that are beneficial to human health. Research supports that some of these foods, as part of an overall healthful diet, have the potential to delay the onset of many age-related diseases. These observations have led to continuing research aimed at identifying specific bioactive components in foods, such as antioxidants, which may be responsible for improving and maintaining health.
Antioxidants are present in foods as vitamins, minerals, carotenoids, and polyphenols, among others. Many antioxidants are often identified in food by their distinctive colours-the deep red of cherries and of tomatoes, the orange of carrots, the yellow of corn, mangos, saffron, the blue-purple of blueberries, blackberries and grapes.
Well-known components of food with antioxidant activities are vitamins A, C, and E- carotene, the mineral selenium, and more recently, the compound lycopene.
Antioxidants in plants' roots have been used to stop cellular damage or oxidative injury arising from free radicals or reactive oxygen species (ROS) in varying degrees. ROS has been shown that the fundamental mechanism underlying a number of human degenerative disorders, diabetes, inflammation, viral infections, auto-immune pathologies, sexual and reproductive disorders, and digestive disorders.
Accumulated evidence suggests that ROS can be scavenged through chemo-prevention utilising antioxidant compounds present in foods (including fishes) and medicinal plants. Antioxidants are compounds and reactions, which dispose, scavenge and suppress the formation of ROS, or oppose and sometimes reverse their actions.
Director of basic and translational research in the Feist-Weiller Cancer Centre, Louisiana State University (LSU) Health Sciences Centre-Shreveport, United States, Prof. James A. Cardelli, said: "The investigational agent used in the trial, Polyphenon E (provided by Polyphenon Pharma) may have the potential to lower the incidence and slow the progression of prostate cancer."
However, some human trials have found contradictory results. The few trials conducted to date have evaluated the clinical efficacy of green tea consumption and few studies have evaluated the change in biomarkers, which might predict disease progression.
Cardelli and colleagues conducted this open-label, single-arm, phase II clinical trial to determine the effects of short-term supplementation with green tea's active compounds on serum biomarkers in-patients with prostate cancer. The biomarkers include hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF) and prostate specific antigen (PSA). HGF and VEGF are good prognostic indicators of metastatic disease.
The study included 26 men, aged 41 to 72 years, diagnosed with prostate cancer and scheduled for radical prostatectomy. Patients consumed four capsules containing Polyphenon E until the day before surgery - four capsules are equivalent to about 12 cups of normally brewed concentrated green tea. The time of study for 25 of the 26 patients ranged from 12 days to 73 days, with a median time of 34.5 days.
Findings showed a significant reduction in serum levels of HGF, VEGF and PSA after treatment, with some patients demonstrating reductions in levels of greater than 30 per cent, according to the researchers.
Cardelli and colleagues found that other biomarkers were also positively affected. There were only a few reported side effects associated with this study and liver function remained normal.
"These studies are just the beginning and a lot of work remains to be done, however, we think that the use of tea polyphenols alone or in combination with other compounds currently used for cancer therapy should be explored as an approach to prevent cancer progression and recurrence," Cardelli said.
Professor of Oncology, Urology and Pharmacology at the Johns Hopkins Kimmel Cancer Centre, United States, William G. Nelson, V., believes the reduced serum biomarkers of prostate cancer may be attributable to some sort of benefit relating to green tea components.
Nelson, who is also a senior editor for Cancer Prevention Research added: "Unfortunately, this trial was not a randomised trial, which would have been needed to be more sure that the observed changes were truly attributable to the green tea components and not to some other lifestyle change (better diet, taking vitamins, etc) men undertook in preparation for surgery.
However, this trial is provocative enough to consider a more substantial randomised trial."
In collaboration with Columbia University in New York City, the researchers are currently conducting a comparable trial among patients with breast cancer. They also plan to conduct further studies to identify the factors that could explain why some patients responded more dramatically to Polyphenon E than others. Cardelli suggested that additional controlled clinical trials should be done to see if combinations of different plant polyphenols were more effective than Polyphenon E alone.
"There is reasonably good evidence that many cancers are preventable and our studies using plant-derived substances support the idea that plant compounds found in a healthy diet can play a role in preventing cancer development and progression," said Cardelli.
Also, Procin-X, a Nigerian-made drug for prostate enlargement, has shown great promise in relieving the symptoms of prostate enlargement and preventing prostate cancer.
The herbal preparation was developed by Dr. Mathew O. Origbo, of Supreme Ormed Option Limited, Sapele, Delta State. Origbo, a British-trained Surveyor, was a former president of the Nigerian Association of Chambers of Commerce, Mines and Agriculture (NACCIMA).
Procin-X, which is for prostate enlargement, comes in 200-milligram capsules. It is an herbal product manufactured from four local plants - Boerhavia spp, Seteria spp, Platosma spp and Alchornea spp.
Origbo told The Guardian: "It possesses anti-inflammatory and antibiotic properties. It achieves full recovery in most cases. For men over 40 years old, it is an active preventive therapy. It makes unnecessary, dangerous and expensive surgical operations and is an effective treatment for a wide spectrum of stubborn infections.
"It is a cure for prostate enlargement and with all due respect for the medical field, this is an area where there is a still a lot of ignorance with regards to prostate enlargement. We have quite a large number of patients who come here with injured male organs arising from the inability of medical personnel to insert catheter. That tells you the level of ignorance that is in the field."
Pharmaton has also developed Seresis- an optimal dietary supplement containing antioxidants such as Vitamins C and E, beta-carotene, selenium yeast and two standardised extracts: LE1005 from tomatoes and VV101 from grape seeds.
Seresis in clinical trials has been shown to help maintain a good level of vitamins and antioxidants in the whole body and is thus intended to help preventing or delaying cell damages deriving from free-radical formation. It offers a valid protection from environmental stress, thereby helping to prevent premature ageing and to preserve a radiant skin.
Chakravarthy, who is also a consultant ophthalmic surgeon at the Royal Hospital in Belfast, said: "Late AMD causes severe sight loss and has a huge economic impact both in terms of the effects of sight loss itself and in terms of the expensive treatments that are needed to deal with the condition.
"Up to 500 people a year in Northern Ireland will lose sight in one or both eyes as a result of late AMD. We wanted to carry out the study as prevention of progression to late AMD can result in a reduced financial and societal burden."
As the macula of the eye is very rich in antioxidants the researchers wanted to see if a supplement called CARMA (Caroteneoids and Co-antioxidants in Age-related Maculopathy) containing the carotenoids lutein and zeaxanthin could help slow down AMD.
The supplement also contained Vitamins C, E and Zinc, which had been used in a previous study. The latest study showed that intake of high levels of both carotenoids preserved the macular pigments, slowing down the progression from early AMD to late AMD. In contrast, the macular pigments of participants in a placebo group declined steadily.
Chakravarthy added: "These findings are important because this is the first randomised controlled clinical trial to document a beneficial effect through improved function and maintained macular pigments.
"Further research is needed to confirm these findings and to identify the numbers needed to treat, to prevent one case from progressing from early to late AMD."
To test whether quercetin supplements benefit energy production in humans, Davis' group enlisted seven men and five women, an average of 23 years old, to participate in a crossover study. At the beginning of the study, investigators measured students' maximum oxygen uptake and the number of minutes they could ride a stationary bike.
For seven days, the participants followed their regular routines and diet, but drank Tang plus placebo, twice daily. For another seven-day period, the participants drank Tang containing 500 milligrams quercetin. The investigators again measured the volunteers' maximum oxygen uptake and exercise endurance. This process was repeated after another seven-day period when volunteers drank similar tasting and coloured Tang without quercetin.
Compared with days of no supplementation, the quercetin supplement periods were associated with a modest - nearly four per cent - increase in maximum oxygen uptake. Quercetin was also associated with a 13 per cent increase in "ride time" before the volunteers were too fatigued to continue.
These findings suggest quercetin "may be important in relieving fatigue that keeps (people) sedentary," Davis commented in a university press release.
If confirmed in further investigations, quercetin supplementation may become a beneficial endurance booster for regular exercisers and athletes alike, Davis and colleagues surmise.
