Lecture 2: Natural Products

Drug leads, active principles of NHPS and nutracueticaJuls
A lot of unique natural product drugs
Occur naturally as chemical defenses in plants, fungi, marine organisms and bacteria against their enemies.
Almost every biological activity invented nature.
Enemies adapt to toxins, plant must invent new natural defence mech.
Bioactive natural products are secondary metabolites. Defence compounds from primary metabolites.
Jujube leaf
Used skin problems.
Screening many plants showed activity of jujube against skin cancer.
Bioassay guided isolation.
NP identification: structure elucidation
Once pure active found, natural product uses NMR spectra like COSY or HMBCOr to determine structures.
X-ray analysis is better when crystals are available.
Terpenes
Saturated carbon in multiples of 5.
Two pathways leading to Terpenes. Cystol (MV) or plastid (MEP)
Terpene synthesis involves intermediates of

C10 monoterpenes (limonene and menthol) – found in glandular hairs
C15 sesquinterpenes – found glandular hairs – also in parthenolifr in feverfew anti-inflammitory cascade of Nf-kb(master gene inflammatory properties)
C20 diterpens and C30 triterpenes

Taxol is diterpene. In pacific yew tree. Taxol prevents tubulin assembly. Treatment for breast and ovarian cancer.
Phenolics
Aromatic carbon ring structure.
Biosynthesis begins with phenylalanine (an amino acid).
Benzoic acid is formed by chain shortening, vanillin and salicylic acid (analgesic = pain relief), acetyl derivative is ASA in aspirin.

Simple phenolcs are echinecea, cereals, and carrot family.

Flavonoids a major group of phenolics
Anthocyanins (potent antioxidant) coloured pigments in berries and flowers.
Darked skinned berriie are among the most potent anitoox. –redwine and antibacterial lagents in cranberries.
Alkaloids
Classified by parent ring structure.
Bioactive n heterocylces
Cocain: tropane carbon. Nervous system stimulant.