| Photoactivated Radical Generator | Not Available | 2 | 8 | Details |
| Photoaffinity Labels | Biologically active molecules which are covalently bound to the enzymes or binding prot... more | 1 | 2 | Details |
| Photochemotherapy | Not Available | 1 | 1 | Details |
| Photoenhancer | Not Available | 2 | 59 | Details |
| Photoreceptors, Microbial | Light absorbing proteins and protein prosthetic groups found in certain microorganisms.... more | 2 | 5 | Details |
| Photosensitizing Activity | Not Available | 3 | 11 | Details |
| Photosensitizing Agents | Photosensitizing agents are drugs that can make the skin more sensitive to UV radiation... more | 159 | 1773 | Details |
| Photosensitizing Agents for Phototherapy | Included in this category are drugs that are used to therapeutic advantage for their ph... more | 6 | 16 | Details |
| Phthalazines | Bicyclic heterocyclic compounds containing a BENZENE ring fused to PYRIDAZINE. | 3 | 9 | Details |
| Phthalic Acids | A group of compounds that has the general structure of a dicarboxylic acid-substituted ... more | 13 | 37 | Details |
| Phthalimides | The imide of phthalic acids. | 7 | 38 | Details |
| Physicochemical Phenomena | The physical phenomena describing the structure and properties of atoms and molecules, ... more | 0 | 0 | Details |
| Physiological Phenomena | The functions and properties of living organisms, including both the physical and chemi... more | 91 | 962 | Details |
| Phytochemicals | A broad range of biologically active compounds which occur naturally in plants having i... more | 3 | 14 | Details |
| Phytoestrogens | PLANT EXTRACTS and compounds, primarily ISOFLAVONES, that mimic or modulate endogenous ... more | 6 | 42 | Details |
| Phytol | Acyclic diterpene used in making synthetic forms of vitamin E and vitamin K1. | 8 | 48 | Details |
| Phytosterols | A class of organic compounds known as STEROLS or STEROIDS derived from plants. | 2 | 9 | Details |
| Picolines | A group of compounds that are monomethyl derivatives of pyridines. (From Dorland, 28th ed) | 10 | 79 | Details |
| Picolinic Acids | Compounds with general formula C5H4N(CO2H) derived from PYRIDINE, having a carboxylic a... more | 2 | 7 | Details |
| Pigments, Biological | Any normal or abnormal coloring matter in PLANTS; ANIMALS or micro-organisms. | 88 | 478 | Details |
| Pimelic Acids | A group of compounds that are derivatives of heptanedioic acid with the general formula... more | 1 | 2 | Details |
| Pinus | Not Available | 2 | 6 | Details |
| Pipecolic Acid and derivatives | Not Available | 0 | 0 | Details |
| Piper nigrum | Not Available | 1 | 16 | Details |
| Piperazine and Derivatives | Not Available | 2 | 5 | Details |