Fatty acids (e.g. Omega 3s, EFAs, PUFAs, DHA, EPA): mostly oil soluble, slightly soluble in ethanol

Triglycerides (triacylglycerols; fixed oils such as Olive or Almond are mostly composed of triglycerides): very slightly soluble in ethanol, not in water, and will dissolve many oil soluble compounds

Waxes (e.g. beeswax): soluble in warm oils but not in cold

Phospholipids (e.g. lecithin, phosphatidyl choline, PS): are emulsifiers

Alkamides (e.g. the tingly isobutylamides in Echinacea spp. & Acmella oleracea): soluble in 40–60% ethanol

Polyacetylenes (e.g. arctinal from Arctium lappa; PHT from Bidens): similar to alkamides

Unsaponifiable matter (anything dissolved in an oil, such as olive, which is not a fatty acid or triglyceride; includes oil-soluble vitamins, phytosterols, carotenoids, etc.)

Essential oils are not lipids, but rather are composed mainly of small terpene compounds; soluble in mid- to high-percentage ethanol, fixed oils, slightly soluble in water

Free amino acids at pH 7 are zwitterions very water soluble, generally soluble in low percentage ethanol

Some sulfur-containing amino acid derivatives (e.g. ajoene and sulfides from Allium sativum): oil soluble, some sulfides have limited water solubility

Cyanogenic glycosides (e.g. amygdalin, prunasin): soluble in water, more so in hot water, somewhat soluble in cold ethanol, more so in hot ethanol

Amines like alkaloids: generally more soluble in acidic media; amine salts : water soluble (ionic)

Methylxanthines (e.g. cafffeine): hot water soluble, less so in cold water

Peptides (e.g. glutathione): generally water soluble, depends on pH (lose solubility at isoelectric point)

Proteins: generally water soluble, depends on pH (lose solubility at isoelectric point)

Enzymes: generally water soluble, depends on pH (lose solubility at isoelectric point)

As a general rule, terpenoids tend to be oil and high-percentage ethanol soluble. Triterpene and steroidal saponins are water soluble because of their sugar groups. The smaller terpenoids (in essential oils) have very limited solubility in water, and are soluble in fixed oils and ethanol. Small terpenes include

The larger terpenes are not volatile and tend to be oily or resinous substances. In general, they are soluble in fixed oils or high percentage ethanol. Many resinous materials are composed of larger terpenes (and/or polyphenolic aglycones)

The aglycones of triterpenoid saponins (sapogenins) are practically insoluble in water or ethanol, while their glycosidic forms are highly water soluble and amphiphilic (soapy/foamy).

Plant steroids are oil-soluble, with the exception of glycosidic forms (e.g. steroidal saponins and cardiac glycosides); the latter are slightly water soluble

Phytosterols: soluble in fixed oils and high percentage ethanol

Steroidal saponins: aglycones are not water soluble; glycosidic forms are

Cardiac glycosides: slightly water soluble; more so in dilute alcohol; aglycones are oil soluble

The pH of the solution influences the solubility of alkaloids. In general, alkaloids are more oil soluble in high pH (alkaline) solutions. Conversely, they are more water soluble in acidic solutions. Most alkaloids are soluble in mid- to high-percentage ethanol/water solutions.

The purple and yellow betalain alkaloids (found in beets, pokeberries, prickly pear cactus, amaranth, etc.) are very soluble in water and will remain dissolved in low- to mid-percentage ethanol solutions.

The isoquinoline alkaloids are soluble in moderate- to high-ethanol solutions with the exception of berberine, which is far more water soluble than the others.

The N-oxide forms of pyrrolizidine alkaloids (PAs) are very water soluble. PAs are soluble in low-pH solutions, but insoluble in high-pH solutions. They are also soluble in ethanol and in organic solvents such as acetone. They are nearly insoluble in fixed oils.

Mixing water and ethanol together (hydroethanolic), in different proportions, determines the overall polarity of the solvent mixture. The higher the water percentage and the lower the ethanol, the higher the overall polarity (since water is more polar than ethanol). Conversely, the lower the water percentage and the higher the ethanol, the lower the overall polarity will be (since ethanol is less polar than water). So a 24 % EtOH tincture would have 76 % water and would be very polar, while a 95 % EtOH tincture would have only 5 % water and would be much less polar.
For detailed solubility of individual, isolated molecules, consult the Merck Index (Merck & Co., Inc., Whitehouse Station, NJ).
Solubility in a given solvent is influenced by the polarity of a molecule’s skeleton and functional groups, the molecular size, temperature, the pH of the solution, and other factors. The solubility of an isolated compound is easy to determine, but this may change in the complex matrix of a medicinal plant extract. The general principle: like dissolves like. A high-polarity solvent will pull high-polarity molecules out of the herbal material; a low-polarity solvent will select for low-polarity molecules.

adapted from The Modern Herbal Dispensatory by Thomas Easley and Steven Horne and The Herbal Medicine-Maker's Handbook by James Green