< April, 2014 >
II. Research on medicinal plants
By Flor Lacanilao, PhD
(NOTE: This article has been previously published in Star Science, Philippine STAR, 2 February 2006. It is posted here with the author's permission)
The Department of Health has been promoting products of medicinal plants as alternative medicines. Their low costs and effectiveness will help many Filipino families, announced the DOH secretary, as they have been a subject of “extensive research by Filipino scientists.”
According to the Department of Science and Technology, 102 plants have been "scientifically validated for safety and efficacy." Ten of these plants are under different stages of development, and that studies have been completed on sambong, lagundi, and akapulko. From sambong and lagundi alone, a local maker of herbal drugs is earning millions of pesos. These we are told.
But recent reviews of the scientific literature on herbal medicinal products have a warning: THEY ARE NOT FREE OF RISK. One such review was conducted by scientists from the Department of Complementary Medicine, Universities of Exeter and Plymouth, United Kingdom. It was published in the journal Pharmacoepidemiology and Drug Safety in 2004.
The study focused on the toxicity, interactions, and quality of herbal products. Toxicity data indicate that some herbal drugs "have the potential to cause serious adverse events and fatalities." They "affect pharmacokinetic and pharmacodynamic factors and thus cause herb-drug interactions." Contamination, adulteration, or substitution of botanical material has repeatedly put patients in danger, and that most often implicated are herbal drugs from Asia.
The review concludes that "the widespread notion of herbal drugs being inherently safe is naive at best and dangerous at worst," and that more research and more information are required to ensure consumers’ safety.
This paper examines the extent and quality of research done on sambong, lagundi, akapulko, ampalaya, coconut oil, and virgin coconut oil. Are there enough scientific studies to justify the booming market of their medicinal products?
Search for quality references
References were obtained through the Google Scholar, which provides ways to search for scholarly journals, books, and unpublished papers. Some of them have abstracts and a few have full texts. Sourced materials are from academic publishers, professional societies, universities, and other scholarly organizations.
The search for literature used scientific names as keywords for sambong (Blumea balsamifera), lagundi (Vitex negundo), akapulko (Cassia alata), and ampalaya (Momordica charantia). These plants have different names in other countries, and their scientific names are used in international publications. For coconut, the keywords are coconut oil and virgin coconut oil. To focus on articles with them as the main subjects, the search was confined to article titles that contain the keywords.
Why international journals
Retrieved titles were examined to separate those published in international journals. These are journals covered in the Clinical Medicine and Life Sciences editions of Current Contents (CC). Clinical Medicine covers 1,229 journals and Life Sciences, 1,368. They are indexes of the Institute for Scientific Information (www.isinet.com). The journals in these CC editions are also covered in ISI’s Science Citation Index Expanded. No Philippine medical journal has yet met the standards for inclusion in any of the above indexes.
The same citation index is the source of publication and citation data used in ranking nations, universities, or individuals when assessing their performance in science and technology. Examples have appeared in the journals Nature and Science, and the magazine Scientific American. In last year’s evaluation of universities, for instance, none from the Philippines made it to the first 100 in the Asia-Pacific or the first 500 in the world (http://ed.sjtu.edu.cn/ranking.htm).
My earlier article in this column discusses the importance of publishing studies in international journals or ISI-indexed journals. Such published paper is called scientific paper or valid publication. A research paper published elsewhere is called gray literature because it is not adequately peer-reviewed, and it is not widely accessible for international peer verification. It is not referred to as a scientific study. In this paper, journals covered by Clinical Medicine and Life Sciences editions of Current Contents will be called "int. journal" or journal.
Data don’t support claims
Results of the search for references yielded 628 titles, with 245 (39 percent) from int. journals. The int. journal papers consisted of the following: 2 titles each for virgin coconut oil and sambong, 9 for lagundi, 20 for akapulko, 97 for coconut oil, and 115 for ampalaya. From the 245 journal papers, Filipino authors in the country contributed only four (see Table).
One journal paper with Filipino authors is on bioactivities of akapulko by IM Villasenor et al. from UP Diliman’s Institute of Chemistry. It was published in Phytotherapy Research in 2002. Another journal paper by Filipino authors is on virgin coconut oil by AL Agero and VM Verallo-Rowell of the Makati Medical Center. Their paper, which was published in Dermatitis in 2004, shows that virgin coconut oil is effective and safe when used as a moisturizer. The other two journal papers by Filipinos are on antimutagenic properties of ampalaya by AP Guevara et al., also of UP Diliman’s Institute of Chemistry. Their papers appeared in Mutation Research in 1990 and in Phytochemistry.
Summary of information from titles and abstracts of published papers on five medicinal plants
|Keyword in title of article
||No. of titles retrieved
||No. published in int. journals (%)
||No. in int. journals with Filipino authors
||Medical indications (in human or animals)
|Blumea balsamifera (Sambong)
|Vitex negundo (Lagundi)
||Anti inflammatory, liver protection
|Cassia alata (Akapulko)
||Antimicrobial, other bioactivities
|Momordica charantia (Ampalaya)
||Reduces sugar level
||Various health conditions
|Virgin Coconut oil
||Reduces cholesterol in rats; moisturizer
||Efficacy and safety not established
|Note: Int. journals are those covered in the Clinical Medicine and Life Sciences editions of Current Contents.
Ampalaya showed the largest number of int. journal papers, 115 (49 percent). Authors are dominated by scientists from India. Only two papers are authored by our researchers. Most of the titles are medicinal, and relate to blood sugar level or show hypoglycemic effect in laboratory animals. One article published in 2003 reviews ampalaya’s efficacy and safety. It concludes that adequately powered, randomized, placebo-controlled trials are needed to properly assess safety and efficacy before ampalaya can be routinely recommended.
Coconut oil yielded also a large number of journal papers, 97 (33 percent), but none by Filipino authors in the country. Almost all of the titles contain a wide variety of health-related and clinical terms – infant nutrition, organ function, metabolic effects, skin disease, STDs, atherosclerosis, platelet function, serum lipids, etc. And just about all are on laboratory or domestic animals. No review of literature was seen on the efficacy and safety of coconut oil as medicine. None of the titles have HIV or AIDS.
In sum, results show that out of 628 titles examined on the five local plants, 245 (39 percent) are scientific papers (int. journal papers). The four papers with Filipino authors are on akapulko, virgin coconut oil, and ampalaya. There are many retrieved titles with Filipino authors or published in the country; 10 are on coconut oil. They are among the non-int. journal papers and can hardly be verified by international peers. As mentioned above, such papers don’t count in research evaluation. They have doubtful validity. Hence, they are not considered here.
Consumers’ safety at risk
The data show that there are no sufficient scientific studies to justify the development of medicinal products from sambong, lagundi, akapulko, and virgin coconut oil. Where are the results of the extensive research on medicinal plants by Filipino scientists, as claimed by the DOH and DOST? I think it is clear that the state of scientific research in the country, or elsewhere, on the four products does not support the government’s campaign to use these products.
The potential of ampalaya and coconut oil for developing drugs is indicated. But problems with toxicity and interactions with prescribed drugs require more research. Hence, considering all examined data, the answer to the question asked in the introduction is no, there are not enough valid research done on the efficacy and safety to support the booming market of medicinal and food supplements from these plants. And I will focus the rest of my discussion by asking a few more.
Does testimonial or anecdotal evidence on the effects of drugs derived from plants justify the government’s promotion of their use? What is our health department doing to guard the consumers’ safety in view of scientific findings that herbal drugs are not free of risk? Why did the Bureau of Food and Drugs approve a product of the much-publicized virgin coconut oil? There are only two scientific studies on VCO, one in rats and another in human as moisturizer. On the other hand, numerous studies on saw palmetto (from the berry of a dwarf palm found in the US) have repeatedly verified its viable treatment of enlarged prostate in men. It has been clinically proven to relieve the symptoms of medically diagnosed benign prostate enlargement in men. But it is yet to be evaluated by the US Food and Drug Administration.
Let me stress the recent findings of the scientific review on herbal drugs mentioned above. All herbal medicinal products (HMPs) contain a variety of pharmacologically active constituents, and users often combine HMPs with prescribed drugs. "Thus herb-drug interactions are a real possibility." Since they are natural products, some constituents can be good or harmful to body systems or organs. Each of these constituents has not been thoroughly studied to know at what amount and required time each is effective in giving the cure or harm to the body. The studies on our medicinal plants seen above confirm that most of the claimed benefits from their products are anecdotal, testimonial, or from gray literature. And scientific reviews on the use of herbal products worldwide reveal numerous examples of liver, kidney, or other organ damage.
More research is required on our plant medicinal products, particularly on the harmful constituents, to minimize the risk they pose to consumers’ health. The excellent training of our medical doctors is shown by their reluctance to prescribe herbal drugs routinely.
Improving research funding
Finally, on the question of promoting science in the country, which starts with the proper publication of results so that these can be taken seriously: Why hasn’t the DOST made publication experience in int. journals a requirement for funding proposals? "Just printing results doesn’t validate them." And non-int. journal papers don’t count in established international evaluation of research performance. Changing our funding practice will not only save money but will also justify increasing the R&D budget. It will improve the state of scientific research, and someday this may make herbal products effective and safe medicines. We have some able researchers (scientists) on natural products, including those who authored the four papers on medicinal plants mentioned above. They are the ones who should be given support and enough funds to be able to do and write enough science. The future of drug development from our natural products depends on scientists like them.
A final note to our administrators of funding agencies: Yes, we are a poor country, and "if you think research is costly, try disease."
The author got his PhD in zoology (specialization in comparative endocrinology) from the University of California at Berkeley. His published papers in international journals include those in Gen Comp Endocrinol, Proc Soc Exp Biol Med, Comp Biochem Physiol, and Science. Lacanilao is a retired professor of marine science at UP Diliman and a former chancellor of UP Visayas. E-mail him at flor_lacanilao @ yahoo.com.
Posted by admin on 03/14/2007 10:10 AM