The invention provides a method for extracting medicinal substances from
Periplaneta American Linn, which comprises the following steps: A,
alcohol extraction: killing and soaking larvae in
alcohol; freezing the larvae at a low temperature;
cracking shells, carrying out coarse-
sizing, placing in an extractor and soaking in
alcohol; thermal-
reflux alcohol-extracting, recovering the
drug liquid, placing in a separator and carrying out the oil-water separation; filtering and concentrating the separated
drug liquid; discharging and cooling the
drug liquid to obtain the medicinal substances; and B,
water extraction: pouring the materials of alcohol extraction into
distilled water; carrying out heating extraction; recovering and placing the drug liquid in the separator and carrying out the oil-water separation; and filtering and concentrating to obtain the medicinal substances. Compared with the prior art, the method of the invention improves the extraction yield and increases the total content of
amino acid as well as the contents of polypeptide,
protein,
chitin,
chitosan and the like in the extracted medicinal substances, and is particularly characterized in that the unpleasant
odor is eliminated by low-temperature freezing before the extraction, therefore, the extracted medicinal substances have almost no unpleasant
odor from the original extract while more bioactive substances are preserved.