The use of and search for drugs and dietary supplements derived from plants have accelerated in recent years. Ethnopharmacologists, botanists, microbiologists, and natural-products chemists are combing the Earth for phytochemicals and “leads” which could be developed for treatment of infectious diseases. While 25 to 50% of current pharmaceuticals are derived from plants, none are used as antimicrobials. Traditional healers have long used plants to prevent or cure infectious conditions; Western medicine is trying to duplicate their successes. Plants are rich in a wide variety of secondary metabolites, such as tannins, terpenoids, alkaloids, and flavonoids, which have been found in vitro to have antimicrobial properties. This review attempts to summarize the current status of botanical screening efforts, as well as in vivo studies of their effectiveness and toxicity. The structure and antimicrobial properties of phytochemicals are also addressed. Since many of these compounds are currently available as unregulated botanical preparations and their use by the public is increasing rapidly, clinicians need to consider the consequences of patients self-medicating with these preparations.

Plant Products as Antimicrobial Agents

The therapeutic properties of light have been known for thousands of years, but it was only in the last century that photodynamic therapy (PDT) was developed. At present, PDT is being tested in the clinic for use in oncology--to treat cancers of the head and neck, brain, lung, pancreas, intraperitoneal cavity, breast, prostate and skin. How does PDT work, and how can it be used to treat cancer and other diseases?

Photodynamic therapy for cancer

In diverse organisms, calorie restriction slows the pace of ageing and increases maximum lifespan. In the budding yeast Saccharomyces cerevisiae, calorie restriction extends lifespan by increasing the activity of Sir2 (ref. 1), a member of the conserved sirtuin family of NAD(+)-dependent protein deacetylases. Included in this family are SIR-2.1, a Caenorhabditis elegans enzyme that regulates lifespan, and SIRT1, a human deacetylase that promotes cell survival by negatively regulating the p53 tumour suppressor. Here we report the discovery of three classes of small molecules that activate sirtuins. We show that the potent activator resveratrol, a polyphenol found in red wine, lowers the Michaelis constant of SIRT1 for both the acetylated substrate and NAD(+), and increases cell survival by stimulating SIRT1-dependent deacetylation of p53. In yeast, resveratrol mimics calorie restriction by stimulating Sir2, increasing DNA stability and extending lifespan by 70%. We discuss possible evolutionary origins of this phenomenon and suggest new lines of research into the therapeutic use of sirtuin activators.

Small molecule activators of sirtuins extend Saccharomyces cerevisiae lifespan

Resveratrol, a constituent of red wine, has long been suspected to have cardioprotective effects. Interest in this compound has been renewed in recent years, first from its identification as a chemopreventive agent for skin cancer, and subsequently from reports that it activates sirtuin deacetylases and extends the lifespans of lower organisms. Despite scepticism concerning its bioavailability, a growing body of in vivo evidence indicates that resveratrol has protective effects in rodent models of stress and disease. Here, we provide a comprehensive and critical review of the in vivo data on resveratrol, and consider its potential as a therapeutic for humans.

Therapeutic potential of resveratrol: the in vivo evidence.

Advances in flavonoid research since 1992.

Caraipa densifolia Mart. (Clusiaceae) has afforded the new lupene derivative 3 beta-hydroxy-28-p-coumarolyoxy-lup-20(29)-en-27-oic acid (8), whose structure was deduced by chemical correlation with betulin (6). Simiarenol (1), taraxerone (2), friedelin (3), lupeol (4), betulinic acid (5), betulin (6), and beta-sitosterol-beta-D-glucoside (7) were also isolated in this study.

3 beta-hydroxy-28-P-coumaroyloxy-lup-20(29)-en-27-oic acid from Caraipa densifolia.

In 1999, the Department of Medicinal Chemistry and Pharmacognosy at the College of Pharmacy, University of Illinois (UIC) at Chicago was funded to establish a Botanical Dietary Supplements Research Center from the National Institutes of Health (NIH). The emphasis of the UIC/NIH Center for Botanical Dietary Supplements Research (CBDSR) is botanical dietary supplements (BDS) for women’s health. The Center’s research has focused on BDS that may improve women’s health and quality of life, specifically in the areas of menopause, premenstrual syndrome, and persistent urinary tract infections. Center investigators have overcome many challenges associated with botanical dietary supplements research, including acquiring and identifying plant species for investigation, isolating and identifying active constituents, elucidating the mechanisms of action of these botanicals, and conducting Phase I and Phase II clinical studies. Black cohosh [Actaea racemosa L. (Ranunculaceae)] has been used as a model to illustrate th...

https://www.tandfonline.com/doi/pdf/10.1080/13880200902988637

Research highlights from the UIC/NIH Center for Botanical Dietary Supplements Research for Women's Health: Black cohosh from the field to the clinic.

Two lignans of known structure, (+)-syringaresinol, a cytotoxic agent, and (+)-nortrachelogenin, a compound with demonstrated antileukemic activity, were isolated from a biologically active extract of the stems of PASSERINA VULGARIS.

Plant anticancer agents XXXIII. Constituents of Passerina vulgaris.

Isolation of lupeol from Crataeva benthamii

Aqueous extracts of Pteryxia terebinthina var. terebinthina were shown to possess antiarrhythmic activity. A novel furanocoumarin, pterybinthinone, the known coumarins pteryxin and umbelliferone, and sucrose were isolated from this plant. Attempts to re-isolate a structurally undefined, defibrillatory substance by means of a published protocol were unsuccessful.

Norman R. Farnsworth

Papers

3 beta-hydroxy-28-P-coumaroyloxy-lup-20(29)-en-27-oic acid from Caraipa densifolia.

Research highlights from the UIC/NIH Center for Botanical Dietary Supplements Research for Women's Health: Black cohosh from the field to the clinic.

Plant anticancer agents XXXIII. Constituents of Passerina vulgaris.

Isolation of lupeol from Crataeva benthamii

Biological and Phytochemical Investigation of Plants XV. Pteryxia terebinthina var. terebinthina (Umbelliferae)