Chemical Groups Of Natural Products With Anticancer Properties

Plant-derived natural products with documented anticancer and antitumor properties can be classified into the following chemical groups ():

  • • Aldehydes
  • • Alkaloids
  • • Flavonoids
  • • Glycosides
  • • Lignans
  • • Lipids
  • • Quinones
  • • Phenols and derivatives
  • • Polysaccharides
  • • Proteins
  • • Terpenoids

Aldehydes are volatile substances found (along with alcohols, ketones, and esters) in minute amounts and contributing to the formation of odor and flavor of plant parts. Plants containing aldehydes with anticancer properties include the following:

  • Cinnamomum cassia
  • Mondia whitei
  • Rhus vulgaris
  • Sclerocarya caffra

Alkaloids are weak bases, capable of forming salts, which are commonly extracted form tissues with an acidic, aqueous solvent. Alternatively, free bases can be extracted with organic solvents. Plants containing alkaloids with anticancer properties include the following:

  • Aconitum napellus
  • Acronychia baueri, A. haplophylla
  • Annona purpurea
  • Brucea antidysenterica
  • Calycodendron milnei
  • Cassia leptophylla
  • Chamaecyparis sp.
  • Chelidonium autumnale
  • Ervatamia microphylla
  • Eurycoma longifolia
  • Fagara macrophylla
  • Nauclea orientalis
  • Psychotria sp.
  • Strychnos usabarensis

Flavonoids are widely distributed colored phenolic derivatives. Related compounds include flavones, flavonols, flavanonols, xanthones, flavanones, chalcones, aurones, anthocyanins, and catechins. Plants containing flavonoids with anticancer properties include:

  • Acrougehia ported
  • Angelica keiskei
  • Annona densicoma, A. reticulate
  • Claopodium crispifolium
  • Eupatorium altissimum
  • Glycyrrhiza inflate
  • Gossypium indicum
  • Polytrichum obioense
  • Psorospermum febrifigum
  • Rhus succedanea
  • Zieridium pseudobtusifolium

Glycosides are carbohydrate ethers that are readily hydrolysable in hot water or weak acids. Most frequently, they contain glucose and are named by designating the attached alkyl group first and replacing the -ose ending of the sugar with -oside.

Basis of anticancer/antitumor activity — Glycosides are mainly cytotoxic against certain types of cancer and also demonstrate antiviral and antileukemic properties. Plants containing glycosides with anticancer properties include the following:

  • Phlomis armeniaca
  • Phyllanthus sp.
  • Plumeria rubra (iridoids)
  • Scutellaria salviifolia
  • Wikstroemia indica

Lignans are colorless, crystalline, solid substances widespread in the plant kingdom (mostly as metabolic intermediaries) and having antioxidant, insecticidal, and medicinal properties. Plants containing lignans with anticancer properties include the following:

  • Brucea sp.
  • Juniperus virginiana
  • Magnolia officinalis
  • Plumeria sp.
  • Wikstroemia foetida

Lipids include fatty acids (aliphatic carboxylic acids), fatty acid esters, phospholipids, and glycolipids. Plants containing lipids with anticancer properties include the following:

  • Nigella sativa
  • • Sho-saiko-to, luzen-taiho-to

Quinones are a diverse group of substances generally soluble in organic solvents and not saponified by alkali. They are yellow to red pigments, often constituents of wood tissues, and have toxic and antimicrobial properties. Plants containing quinines with anticancer properties include the following:

  • Kigelia pinnata
  • Koelreuteria henryi
  • Landsburgia quercifolia
  • Mallotus japonicus
  • Nigella sativa
  • Rubia cordifolia
  • Sargassum tortile
  • Wikstroemia indica

Phenols and derivatives are the main aromatic compounds of plants, whose structural formulas contain at least one benzene ring. They serve as odors, fungicidals, or germination inhibitors. Coumarins are especially common in grasses, orchids, citrus fruits, and legumes. Plants containing phenols with anticancer properties include the following:

  • Acronychia laurifolia
  • Angelica gigas, A. decursiva, A. keiskei
  • Gossypium indicum

Polysaccharides and generally carbohydrates represent the main carbon sink in the plant cell. Polysaccharides commonly serve nutritional (e.g., starch) and structural (e.g., cellulose) functions in plants. Some polysaccharides are cytotoxic against certain types of cancer, such as mouse skin cancer, or tumor lines in vitro (e.g., mouse Sarcoma-180). However, most polysaccharides exert their action through stimulation of the immune system (cancer immunotherapy). Plants containing polysaccharides with anticancer properties include the following:

  • Angelica acutiloba
  • Angelica sinensis
  • Burcea javanica
  • Cassia angustifolia, Sargassum thunbergii
  • S. fulvellum, Tamarindus indica

Proteins, similar to carbohydrates, belong to the most essential constituents of the plant body, as they are the building molecules of structural parts and the enzymes. Proteins are indirectly cytotoxic against certain cancer types, acting mainly through the inhibition of various enzymes (l-aspariginase, Tyrosine kinase) or by inducing apoptotic cell death. Plants containing proteins are the following:

  • Acacia confuse
  • Ficus cunia
  • Glycyrrhiza uralensis
  • Momordica charantia
  • Momordica indica
  • Rubia sp., R. cordifolia

Terpenoids are diverse, widely distributed compounds commonly found under groups such as essential oils, sterols, pigments, and alkaloids. They exert significant ecological functions in plants. Momo- and sesquiterpenoids are found as constituents of steam-distillable essential oils. Di- and triterpenoids are found in resins. Terpenoids and sterols often possess alkaloidal properties, thus being cytotoxic in vivo and in vitro against various cancer types, such as human prostate cancer, pancreatic cancer, lung cancer, and leukemia. Plants containing terpenoids and sterols with anti-cancer properties include the following:

  • Aristolochia versicolar
  • Brucea antidysenterica
  • Casearia sylvestris
  • Crocus sativus
  • Glycyrrhiza sp.
  • Mallotus anomalus
  • Melia sp.
  • Maytenus sp.
  • Neurolaena lobata
  • Polyalthia barnesii
  • Rabdosia trichocarpa
  • Seseli mairei
  • Stellera chamaejasme