METHODS FOR ANALYZING P-HYDROQUINONE LEVELS AND RATIOS

1 . A compound selected from the group consisting of:

or a stereoisomer, a mixture of stereoisomers, and/or a salt thereof.

2 . The compound of claim 1 which is

or a stereoisomer, a mixture of stereoisomers, and/or a salt thereof.

3 . The compound of claim 1 or 2 which is

or a salt thereof.

4 . The compound of claim 1 which is

or a salt thereof.

5 . The compound of claim 1 which is

or a salt thereof.

6 . (canceled)

7 . The compound of claim 1 which is

or a salt thereof.

8 . A method of determining the level of one or more para-hydroquinones in a first sample, the method comprising:

acylating the one or more para-hydroquinones in the first sample to one or more para-hydroquinone derivatives by treatment with an alkyl carboxylic acid, an activated alkyl carboxylic acid, an alkyl anhydride, or a cyclic anhydride; and

determining the level of the one or more para-hydroquinone derivatives in the first sample.

9 . The method of claim 8 wherein the one or more para-hydroquinones in the first sample are acylated with an alkyl anhydride or a cyclic anhydride.

10 . The method of claim 8 or 9 wherein the one or more para-hydroquinone derivatives are selected from the group consisting of a bis-acetate derivative, a bis-propionate derivative, a bis-butyrate derivative, a bis-succinate derivative, a bis-glutarate derivative, and a bis-diglycolate derivative.

11 . The method of any one of claims 8 - 10 wherein the one or more para-hydroquinone derivatives are bis-acetate derivatives.

12 . The method of any one of claims 8 - 10 wherein the one or more para-hydroquinone derivatives are bis-propionate derivatives.

13 . The method of any one of claims 8 - 10 wherein the one or more para-hydroquinone derivatives are bis-butyrate derivatives.

14 . The method of any one of claims 8 - 10 wherein the one or more para-hydroquinone derivatives are bis-succinate derivatives.

15 . The method of any one of claims 8 - 10 wherein the one or more para-hydroquinone derivatives are bis-glutarate derivatives.

16 . The method of any one of claims 8 - 10 wherein the one or more para-hydroquinone derivatives are bis-diglycolate derivatives.

17 . The method of any one of claims 8 - 16 , further comprising determining the level of one or more corresponding para-quinones in an optional second sample, taken at the same time as the first sample, wherein the one or more para-hydroquinones in the second sample was allowed to auto-oxidize to the one or more corresponding para-quinones.

18 . A method of determining the ratio or reverse ratio of one or more para-hydroquinones to one or more corresponding para-quinones in a first sample, comprising:

(i) determining the level of one or more para-hydroquinone derivatives of the one or more para-hydroquinones in the first sample according to any one of claims 8 - 16 ; and

(ii) determining one or more of the following (a)-(d):

(a) the sum of the level of the one or more para-hydroquinone derivatives and the level of the one or more corresponding para-quinones in the first sample;

(b) the level of one or more corresponding para-quinones in the first sample;

(c) the level of total quinones in the first sample; and

(d) the level of one or more corresponding para-quinones in an optional second sample, taken at the same time as the first sample, wherein the one or more para-hydroquinones in the second sample were allowed to auto-oxidize to the one or more corresponding para-quinones; and

(iii) determining a ratio or reverse ratio of one or more of the following (a)-(d):

(a) the level of the one or more para-hydroquinone derivatives in the first sample to the sum of the level of the one or more para-hydroquinone derivatives and the level of the one or more corresponding para-quinones in the first sample;

(b) the level of the one or more para-hydroquinone derivatives in the first sample to the level of the one or more corresponding para-quinones in the first sample;

(c) the level of the one or more para-hydroquinone derivatives in the first sample to the level of the total quinones in the first sample; and

(d) the level of the one or more para-hydroquinone derivatives in the first sample to the level of the one or more corresponding para-quinones in the second sample.

19 . The method of claim 18 wherein the ratio or reverse ratio of the level of the one or more para-hydroquinone derivatives in the first sample to the sum of the level of the one or more para-hydroquinone derivatives and the level of the one or more corresponding para-quinones in the first sample is determined.

20 . The method of claim 18 wherein the ratio or reverse ratio of the level of the one or more para-hydroquinone derivatives in the first sample to the level of the one or more corresponding para-quinones in the first sample is determined.

21 . The method of claim 18 wherein the ratio or reverse ratio of the level of the one or more para-hydroquinone derivatives in the first sample to the level of the total quinones in the first sample is determined.

22 . The method of claim 18 wherein the ratio or reverse ratio of the level of the one or more para-hydroquinone derivatives in the first sample to the level of the one or more corresponding para-quinones in the second sample is determined.

23 . The method of any one of claims 8 - 22 where the levels are determined by mass spectroscopy.

24 . The method of any one of claims 8 - 22 where the levels are determined by liquid chromatography-mass spectroscopy (LC-MS).

25 . The method of any one of claims 8 - 24 wherein the first sample and the optional second sample are biological samples.

26 . The method of claim 25 wherein the biological samples are selected from the group consisting of a cell sample, bacterial culture, yeast culture, plasma, serum, whole blood, and a biological tissue sample.

27 . The method of any one of claims 8 - 24 wherein the first sample and optional second sample are food samples.

28 . The method of any one of claims 8 - 27 wherein the level(s) which are determined are mass(es), moles, or concentration(s).

29 . The method of any one of claims 8 - 28 wherein the one or more para-hydroquinone derivatives are selected from the group consisting of

or a stereoisomer, a mixture of stereoisomers, and/or a salt thereof.

30 . The method of claim 29 wherein the one or more para-hydroquinone derivatives comprise

or a stereoisomer, a mixture of stereoisomers, and/or a salt thereof.

31 . The method of claim 29 wherein the one or more para-hydroquinone derivatives comprise

or a stereoisomer, a mixture of stereoisomers, and/or a salt thereof.

32 . The method of claim 29 wherein the one or more para-hydroquinone derivatives comprise

or a salt thereof.

33 . The method of claim 29 wherein the one or more para-hydroquinone derivatives comprise

or a salt thereof.

34 . The method of claim 29 wherein the one or more para-hydroquinone derivatives comprise

or a salt thereof.

35 . The method of claim 29 wherein the one or more para-hydroquinone derivatives comprise

or a salt thereof.

36 . The method of claim 29 wherein the one or more para-hydroquinone derivatives comprise

or a stereoisomer, a mixture of stereoisomers, and/or a salt thereof.

37 . The method of claim 29 or 30 wherein the one or more para-hydroquinone derivatives comprise

or a salt thereof.

38 . The method of claim 29 or 31 wherein the one or more para-hydroquinone derivatives comprise

or a salt thereof.

39 . The method of claim 29 or 36 wherein the one or more para-hydroquinone derivatives comprise

or a salt thereof.