Legal Definitions - Markush claim

A Markush claim is a specific type of patent claim, predominantly used in chemical, pharmaceutical, and biotechnology fields, that allows an inventor to define a group of related, but not identical, chemical compounds or components within a larger invention. Instead of listing every single possible variation individually, it defines a core structure or composition and then specifies a list of alternatives for one or more parts of that structure or composition. This is typically phrased using language such as "selected from the group consisting of A, B, C, and D," or "wherein R is A, B, C, or D." It provides a way to claim a class of compounds (a "genus") by listing a limited number of specific examples (the "species") that all share a common inventive concept or function.

Here are some examples to illustrate how a Markush claim works:

• Example 1: Pharmaceutical Compound

  Imagine a pharmaceutical company invents a new drug molecule designed to treat a specific type of cancer. The core structure of the molecule is crucial for its anti-cancer activity, but a small part of the molecule, let's call it "Group X," can be varied to improve its absorption in the body or reduce side effects. A Markush claim for this invention might read:

  "A compound for treating cancer, comprising a core structure Y, wherein Group X is selected from the group consisting of a methyl group, an ethyl group, a propyl group, and a butyl group."

  This claim effectively covers four distinct chemical compounds (methyl-Y, ethyl-Y, propyl-Y, and butyl-Y) under a single claim. It acknowledges that while these groups are chemically different, they all serve a similar function in the context of the invention (e.g., improving drug delivery) and are part of the same inventive concept. This prevents competitors from making minor chemical substitutions to bypass the patent.

• Example 2: Polymer Composition for Packaging

  Consider a materials science company developing a new biodegradable plastic film for food packaging. The main polymer provides the structural integrity, but they discover that adding certain natural fibers can significantly improve its strength and flexibility. A Markush claim for this new film might state:

  "A biodegradable packaging film comprising a polylactic acid base polymer and a reinforcing agent selected from the group consisting of cellulose fibers, hemp fibers, and bamboo fibers."

  Here, the Markush claim protects the invention regardless of which specific natural fiber is used, as long as it's one of the listed options. It recognizes that cellulose, hemp, and bamboo fibers, while chemically distinct, all function as reinforcing agents within the biodegradable film, embodying the same inventive principle of enhancing the film's properties.

• Example 3: Cosmetic Formulation

  A cosmetics company develops a new anti-aging serum that uses a novel delivery system for active ingredients. The delivery system is effective, but different antioxidants can be incorporated to boost its efficacy. A Markush claim for this serum could be:

  "An anti-aging serum comprising a liposomal delivery system and an antioxidant selected from the group consisting of Vitamin C, Vitamin E, and ferulic acid."

  This claim covers formulations where the liposomal delivery system is combined with any of the three specified antioxidants. It allows the patent to broadly protect the inventive serum, acknowledging that these different antioxidants, though chemically distinct, all serve the common purpose of providing anti-aging benefits within the novel delivery system.