A skin-protection composition is shown that comprises stilbenoid(s) and/or stilbenoid-containing extract(s) obtained from Dendrobium plants, such as Dendrobium officinale and Dendrobium nobile for the management of melanogenesis, skin-darkening and skin-aging. More particularly, the usage of Dendrobium ingredients and stilbenoids is shown to reduce the formation of melanin in melanocytes. The usage of Dendrobium ingredients and stilbenoids is also shown to reduce the generation of reactive oxygen species and oxidative free radicals. The use of Dendrobium-derived extracts or ingredients or stilbenoids is shown in the formulation of skin-protection, skin-whitening and/or anti-skin aging products.

The present invention provides improved solvents, methods, and systems for isolating purified cannabinoids from various sources. It has been found that C.sub.9 to C.sub.11 non-aromatic hydrocarbon solvents, and especially n-decane, work surprisingly well for crystallization of cannabinoids such as cannabidiol. Some variations provide a method of isolating cannabinoids from a cannabinoid-containing solution, comprising contacting the solution with a C.sub.9-C.sub.11 non-aromatic hydrocarbon solvent (e.g., n-decane) at a first temperature, to generate a mixture; cooling the mixture to precipitate cannabinoids; and isolating the precipitated cannabinoids. Other variations provide a method of isolating cannabinoids from a cannabinoid-containing solution, comprising contacting the solution with a C.sub.9-C.sub.11 non-aromatic hydrocarbon solvent (e.g., n-decane) at a first temperature below the solvent boiling point, to generate a mixture; subjecting the mixture to a second temperature that causes vaporization of the solvent, to precipitate at least some of the cannabinoids; and isolating the precipitated cannabinoids.

Methods for producing hydrogenated cannabigerol and cannabichromene derivatives are disclosed. The methods preserve the aromatic olefins while selectively reducing the nonaromatic olefins using hydrogen gas, a hydrogen gas source, or a mixture thereof and a catalyst to produce the corresponding hydrogenated derivatives, in some aspects, the source of hydrogen gas comprises ammonium formate and/or formic acid. In some aspects, the catalyst is Pd/C or Pt/C.

Some variations provide a process of converting a cannabinoid into a purified cannabinoid derivative, comprising: providing a starting composition comprising a cannabinoid; providing a C.sub.9-C.sub.11 non-aromatic hydrocarbon solvent; introducing the starting composition and the solvent to a conversion reactor; chemically converting some, but not all, of the cannabinoid to a cannabinoid derivative, generating a reaction mixture containing unreacted cannabinoid; conveying the reaction mixture to a crystallization unit; cooling the reaction mixture to precipitate unreacted cannabinoid out of the reaction mixture, thereby generating a mother liquor containing the cannabinoid derivative; and isolating and recovering the cannabinoid derivative from the mother liquor. Systems configured to carry out the disclosed processes are also provided. This invention offers a large-scale solution to economically convert CBD to D9-THC, among many other example. The principles of the invention may be applied to the conversion of various cannabinoids and terpenes into derivative products.