Biologically active extract from

1. A method for treating a retinal pigment epithelium (RPE) related disorder comprising administering to a human in need thereof a composition comprising a physiologically acceptable carrier and a compound having a structure of formula 1:

at an amount effective in enhancing the function of RPE,

wherein each of R 1 and R 2 is selected from the group consisting of C-6-Deoxy-xylo-hexos-4-ulosyl, α-Arabinose, β-Ribose, β-Xylose, β-Lyxose, β-Allose, β-Altrose, β-Mannose, β-Gulose, β-Idose, β-Talose, β-Tagatose, β-Fructose, β-Galactose, β-Glucose, β-Arabinose, and α-Rhamnose, and R 1 and R 2 are attached to C-6 and C-8 positions of formula 1, respectively, as C-glycosides,

and wherein the RPE related disorder is selected from the group consisting of RPE degeneration, age-related macular degeneration, photoreceptor degeneration, choroidal neovascularization, and proliferative retinopathy.

2. The method of claim 1 , wherein R 1 and R 2 are selected from the group consisting of α-Arabinose, β-Arabinose, and β-Xylose, and R 1 and R 2 are attached to C-6 and C-8 positions of formula 1, respectively, as C-glycosides.

3. The method of claim 1 , wherein R 1 and R 2 are the same or different and are selected from the group consisting of C-β-D-glucopyranosyl, C-β-D-galactopyranosyl, C-β-D-xylopyranosyl, C-β-D-arabinopyranosyl, C-α-L-arabinopyranosyl, C-α-L-rhamnopyranosyl and C-6-deoxy-xylo-hexos-4-ulosyl.

4. The method of claim 1 , wherein the compound is selected from the group consisting of

apigenin 6,8-Di-C-α-L-arabinopyranoside,

apigenin 6-C-β-D-Xylopyranosyl-8-C-α-L-arabinopyranoside, and

apigenin 6-C-α-L-Arabinopyranosyl-8-C-β-D-arabinopyranoside.

5. The method of claim 1 , wherein the compound is isolated from Herba Dendrobii.

6. The method of claim 1 , wherein the compound is effective in enhancing the phagocytic ability of RPE.

7. The method of claim 6 , wherein R 1 and R 2 are selected from the group consisting of α-Arabinose, β-Arabinose, and β-Xylose, and R 1 and R 2 are attached to C-6 and C-8 positions of formula 1, respectively, as C-glycosides.

8. The method of claim 6 , wherein R 1 and R 2 are the same or different and are selected from the group consisting of C-β-D-glucopyranosyl, C-β-D-galactopyranosyl, C-β-D-xylopyranosyl, C-β-D-arabinopyranosyl, C-α-L-arabinopyranosyl, C-α-L-rhamnopyranosyl and C-6-deoxy-xylo-hexos-4-ulosyl.

9. The method of claim 6 , wherein the compound is selected from the group consisting of

apigenin 6,8-Di-C-α-L-arabinopyranoside,

apigenin 6-C-β-D-Xylopyranosyl-8-C-α-L-arabinopyranoside, and

apigenin 6-C-α-L-Arabinopyranosyl-8-C-β-D-arabinopyranoside.

10. The method of claim 6 , wherein the compound is isolated from Herba Dendrobii.

11. The method of claim 6 , wherein the phagocytosis of RPE is enhanced.